A PORTABLE WELDING APPARATUS AND ALTERNATOR FIELD OF THE INVENTION

[001] The present invention relates to a power supply for a welding apparatus, and to control means therefore.

[002] The invention is particularly suited for use with portable welders having an alternator power supply driven by a motor or any prime moving source.

BACKGROUND OF THE INVENTION

[003] Welding places severe demands on the power supply in terms of both high voltage and heavy current loads. Today's alternator welders have a number of problems ranging from generating an adequate start up voltage, poor controllability of the weld arc, overheating of the stator and overheating of the rectifier.

[004] These alternators also suffer from control problems when used as a TIG welder.

In addition, there are difficulties in initiating TIG welding.

[005] The applicant does not concede that the prior art discussed in the specification forms part of the common general knowledge in the art at the priority date of this application.

SUMMARY OF THE INVENTION

[006] The present invention provides an alternator including: a stator; a rotor adapted to be driven by a motive power means, the stator having a plurality of spaced apart teeth defining a plurality of winding slots; main windings wound in the slots; at least one control winding is wound in at least some of the slots; the rotor having at least one field winding to generate a magnetic field; the rotor having two or more poles magnetizable by the field winding; wherein, the field winding is powered from the control winding.

[007] The main winding can be a polyphase winding.

[008] The control winding can be a single phase winding.

[009] The single phase control winding can be wound in the same slots as one phase of the main winding.

[010] The control winding can be a polyphase winding.

[011] Each phase winding of the control winding can be wound in the same slots as a corresponding phase winding of the main winding.

[012] In the case of 6 phases only 3 phases of control winding are used and are wound over respective 3 phases of the main winding .

[013] The main winding can be a polyphase winding and each phase of the polyphase main winding can be wound over a section of the stator in proportion to the number of phases.

[014] The polyphase main winding can have 3 phases.

[015] The polyphase main winding can have 6 phases.

[016] The motive power means can drive the rotor at between 100 and 9000 rpm.

[017] The rotor can be preferably driven at between 6000 and 7000 RPM.

[018] The rotor can be a multi-pole rotor.

[019] The rotor can be a 12 pole rotor.

[020] The rotor can be of the claw type or of the 1a.minat.ed type.

[021] Residual magnetism can be used to initiate power for the main winding and control winding as the rotor turns.

[022] On start up, the rotation of the rotor can cause a time varying change in the residual flux passing through at least the control winding to induce a voltage in the control winding.

[023] On start up, the rotation of the rotor can cause a time varying charge in the residual flux passing through at least the main winding to induce a voltage in the main winding.

[024] At least one output of the control winding can be connected to a rectifier.

[025] The current from the rectified control winding voltage from a control winding can be applied to a controller.

[026] The control winding can power the field coil to produce an induced magnetic field in the rotor to power the main winding.

[027] The control winding can be located proximate the air gap in the slots.

[028] In the event of a short circuit on the main winding, the short circuit current in the main winding saturates the magnetic path and causes the flux change in the control winding to collapse, removing power from the field coil whereby saturation effectively acts as a magnetic "open circuit" for time varying magnetic fields.

[029] The alternator described above can include one or more temperature sensors associated with the stator and or temperature sensors are located on heat sinks associated with rectifiers receiving current from the main windings.

[030] The field current controller can be adapted to reduce the field current when the temperature detected by a temperature sensor exceeds a first temperature threshold.

[031] The reduced field current can enable the control winding to generate sufficient power to power one or more indicators. The indicators can be LEDs.

[032] An alternator as described above can include a start voltage generation circuit to produce a higher voltage from the main winding output voltage or control winding output voltage to initiate welding current.

[033] An alternator as described above can include a start voltage control circuit adapted to disconnect the start voltage generation circuit when welding current is established.

[034] The start voltage control circuit can be adapted to reconnect the start voltage generation circuit when the welding current is interrupted.

[035] The start voltage control circuit can include a no volt relay.

[036] The no volt relay can include normally closed contacts to close the circuit including the start voltage generation circuit until a control current derived from the main winding or control winding reaches sufficient magnitude to operate the no volt relay.

[037] The start voltage generation circuit can include a voltage doubler or voltage tripler.

[038] An alternator as described above can include a high voltage generating circuit.

[039] The high voltage generating circuit can be a voltage multiplier.

[040] A low voltage generating circuit can be used for TIG welding.

[041] The present invention also provides a stator lamination for a stator of an alternator, said lamination being generally annular in shape having a curved periphery with a series of radially inwardly directed teeth or fingers to receive windings or coils of wire in which is adapted to be induced a current when the lamination and winding are assembled into an alternator said lamination including at least one projection extending away from said generally annular shape and standing proud of the curved periphery of said lamination.

[042] At least one projection can be of a trapezoidal shape or a truncated triangular shape.

[043] A stator lamination as described above can include between 4 and 16 projections.

[044] A stator lamination as described above can include 12 projections located around the periphery of said lamination.

[045] At least two of the projections can be used to provide a location to weld adjacent laminations together to form a stator.

[046] The projections can be used to orientate and or locate said stator in a predetermined orientation in the alternator housing.

[047] One or more of the projections can be used to mount heat fins to said lamination.

[048] The laminations can have a thickness in the range of 0.15 to 0.8 mm in thickness.

[049] The laminations can have a thickness of 0.35 mm.

[050] The stator slots can have a narrower entrance than the body of the slot.

[051] The entrance of the slots can be defined by a tapered projection.

[052] The entrance of the slots can be defined by a pair of inwardly tapering projections.

[053] A stator including a plurality of laminations as described above, wherein power and control windings are retained in each slot by a corresponding wedge.

[054] The wedge is made of an insulating material.

[055] The present invention further provides a welding control system for a welder which uses an alternator having a rotor and a stator to provide welding current, said welder including a rectifier means to rectify high alternating current frequency produced by said alternator to produce a direct current for welding, said the control system deriving controller current from a separate an control winding wound on the stator of said alternator, said controller current being rectified and regulated to supply power to a rotor field coil system of a salient pole rotor which, when in rotation, energizes the multiphase stator power winding.

[056] Welding apparatus as described above wherein the power windings supplying welding current to power rectifiers and the auxiliary stator windings supplying field excitation current to the rotor field winding via a controller.

[057] Welding apparatus as described above which include a start circuit supplying rotor excitation current from the control winding.

[058] Welding apparatus as described above which include a TIG control circuit, wherein power from the control winding is applied to a TIG control circuit via a voltage multiplier for the production of an arc.

[059] The welding apparatus can include a current detection circuit.

[060] A current detection circuit can be located between one phase of the main winding and associated bridge rectifier.

[061] The arc starting circuit can be adapted to automatically shut down once a main welding arc is established and welding is taking place. .

[062] The arc start circuit can be disabled during non welding times.

[063] Welding apparatus as described above can include capacitors to smooth the DC output from the rectifier.

[064] The above described apparatus can include a battery charger circuit.

[065] Power for the battery charger can be derived from the control winding or main winding or both.

[066] The present invention also provides a control circuit for a welder including an alternator power supply having an exciter circuit, the control circuit including means for increasing the voltage from the control windings when the welder is used in low current mode.

[067] The present invention further provides an alternator including: a rotor with a field winding; a stator with one or more power windings; the stator including one or more control windings connected to supply power to the field winding; and a load supply circuit; the alternator including a voltage multiplier circuit to increase the voltage supplied from the control winding to the load supply circuit.

[068] The alternator can include a bypass switch to connect the output from the control winding to the load supply circuit.

[069] The load supply circuit can be a welding supply circuit.

[070] The present invention further provides an alternator including: a rotor with a field winding; a stator with at least first and second stator windings; at least a first stator winding being connected to supply power to the field winding; the alternator including a voltage sensing relay sensing the voltage generated in at least one of the stator windings; the voltage sensing relay being operatively connected to provide power from a second stator winding to the field windings when the sensing relay control input is low.

[071] The sensing relay can disconnect the second stator winding output from the field winding when the sensing relay is operated by a high input voltage.

[072] A rectifier can be connected to rectify the output from at least one of the stator windings, wherein the sensing relay senses the output of the rectifier.

[073] The present invention also provides a method of operating a welder including an alternator power supply having an exciter circuit, the method including the step of increasing the voltage from the control windings when the welder is used in low current mode.

BRIEF DESCRIPTION OF THE DRAWINGS

[074] An embodiment or embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [075] Figure 1 is an exploded view of the components of an alternator;

[076] Figure 2 is a plan view of a stator lamination;

[077] Figure 3 is a close up view of a portion of the lamination of Figure 1 ;

[078] Figure 4 is a circuit diagram of the alternator, controller and rectifiers and their interconnections ;

[079] Figure 5 illustrates an alternator start up circuit including a rotor field controller for use with the alternator;

[080] Figure 6 illustrates the basic controller printed circuit board and main control panel with the connections shown between the components;

[081] Figure 7 illustrates a three phase main winding (heavy winding) and the three phase winding that supplies power to the controller, supplying controlled power to the rotor fields-shown in the dashed box is the auxiliary winding if desired.

[082] Figure 8 is a circuit diagram of a battery charger according to an embodiment of the invention.

[083] Figure 9 illustrates a circuit adapted for TIG welding

[084] Figure 10 illustrates a circuit diagram of the interconnections of the alternator, controller, rectifiers and welder handle, of another embodiment similar to Figure 4;

[085] Figure 11 illustrates an alternator start up circuit of another embodiment similar to that of Figure 5;

[086] Figure 12 illustrates a controller printed circuit board and main panel with the connections shown between the two components of another embodiment similar to that of Figure

6;

[087] Figure 13 shows a battery charging circuit for 12V and 24V batteries;

[088] Figure 14 shows a coil layout for a 6 phase dual - tri phase winding with control winding placement;

[089] Figure 15 shows a wiring diagram for a 6 phase Tri Phase winding with the position shown for the control winding coils;

[090] Figure 16 shows a coil layout for the tri - phase winding ;

[091] Figure 17 shows a schematic of a handle design with controls for Stick welding

[092] Figure 18 shows a schematic and layout of a handle design with controls for TIG welding;

[093] Figure 19 shows the handle control layout for another version of a welder handle for Arc and Tig welding.

[094] Figure 20 is a drawing of an idler pulley arrangement for belt tensioning.

[095] Figure 21 shows the belt release lever to remove or fit a drive belt

[096] Figure 22 shows a main arc detection circuit;

[097] Figure 23 shows a three phase vector connection of the winding to a three phase high power block rectifier along with the current detection transformer circuit in one phase;

[098] Figure 24 shows a dual - tri phase winding with current detection transformer circuit in one phase connected to three single phase bridge rectifiers;

[099] Figure 25 shows a six phase stator winding of the dual tri - phase stator with current detection transformer circuit connected to a phase of one of 2 three phase block bridge rectifiers;

[0100] Figure 26 illustrates a circuit diagram for an embodiment similar to that of

Figure 10, except that a second alternator with bridge rectifiers is present in the circuit;

[0101] Figure 27 is the PCB and block rectifiers used with the battery charging circuit of Figure 28;

[0102] Figure 28 is another embodiment of a battery charger circuit,

[0103] Figure 29 is a rear view of the front panel of a later version of the mobile welder control panel;

[0104] Figure 30 is an illustration of the PCB showing connections with the panel of

Figure 29 and the PCB of Figure 31 ;

[0105] Figure 31 is an illustration of the PCB of the TIG start-up circuit of Figure 9;

[0106] Figure 32 is a schematic of a plug and switch arrangement used for a TIG welder handle;

[0107] Figure 33 is a schematic of a plug and switch arrangement used for a stick or rod welding handle;

[0108] Figure 34 illustrates a layout front view of a control panel;

[0109] Figure 35 illustrates a circuit diagram of relay 5/1 of used with the klixons described below;

[0110] Figure 36 illustrates a circuit diagram for a voltage tripler that can be used as a substitute for the voltage doubler in Figure 9;

[0111] Figure 37 illustrates a circuit diagram for another voltage tripler that can be used as a substitute for the voltage doubler in Figure 9;

[0112] Figure 38 illustrates a circuit diagram for a voltage doubler that can be used as a substitute for the voltage doubler in Figure 9;

[0113] Figure 39 schematically illustrates an interlock used to interact with the plugs at the end of welding leads;

[0114] Figure 40 illustrates in a diagrammatic fashion, as a large detailed cross section the main, control and auxiliary windings on the stator;

[0115] Figure 41 illustrates in a diagrammatic fashion, as a large detailed cross section the main and control windings on the stator of an alternative winding arrangement;

[0116] Figure 42 illustrates an alternative voltage doubler, plus relay to boost the supply voltage for high voltage start at low welding currents;

[0117] Figure 43 illustrates an improved TIG welding start circuit;

[0118] Figure 44 illustrates the rectifier protection circuit to work with the improved

TIG welding start circuit of Figure 43;

[0119] Figure 45 illustrates an improved start up controller circuit for the starting the main exciter fields of an alternator; and

[0120] Figure 46 illustrates a power control circuit to provide a regulated 12 Volt supply from the regulator board to the TIG board.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0121] Figure 1 shows an alternator 100 with most of the components illustrated in an exploded view. The alternator 100 has a wound stator 1 having a toroidal assembly of laminations 1.1, into which is wound a series of windings 1.2 which terminate in a series of leads MW, CW and AW, the separate windings hereby being referred to by their lead item numbers.

[0122] The alternator 100 has a three phase main winding MW wound into the assembly of stator laminations 1.1. On a prior art alternator the assembly of laminations 1.1 is of a designed width, depending upon alternator output requirements, with each regular lamination being of thickness generally between 0.8 mm and 1.2 mm. However, the stator 1 is made up of the assembly of stator laminations 11 of approximately 100 laminations 20 (see figures 2 and 3) where each lamination 20 is of approximately 0.35mm in thickness as will be described later.

[0123] The stator 1 of Figure 1 is shown with a three phase main winding MW (made up of windings MPHl, MPH2, MPH3 and neutral lead 80), and two additional multiphase windings being control windings CW (made up of windings CPHl, CPH2, CPH3 and neutral lead 81) and auxiliary windings AW (made up of windings APHl , APH2, APH3 with an internal neutral connection to 83) are also present. The windings MW, CW and AW shown in Figure 1, are windings of an alternator embodying the invention, with main winding MW being a high current winding, control winding CW being a lower current winding and auxiliary winding AW being an optional low current winding which could be used for lighting or battery charging etc. The winding AW can be omitted, and battery charging can be done by the use of the main windings MW, as will be described later.

[0124] A salient pole rotor 2 and magnetic pole pieces 2.1, 2.11, 2.12 are mounted on a shaft 2.2, with a rear bearing 2.3 and front bearing 2.4 receiving respective ends of the shaft 2.2. The bearings 2.3 and 2.4 are respectively received in the front housing 5 and rear housing 6 to allow the rotor 2 to rotate, when the alternator 100 is assembled.

[0125] A rotor field coil (see 203 in Figure 5) is wound around the pole pieces and connected to slip rings 8 in Figure 1.

[0126] To prevent lateral movement of the rotor 2 in the front housing 5 a locking washer 2.5 is used to hold the front bearing 2.4 in the front endplate of the front housing 5, which is secured thereto by appropriate screws. The rear end plate of rear housing 6 houses the rear bearing 2.3 and a thrust washer.

[0127] The alternator 100 has an airspace 20.2 (see Figure 3) or distance between the stator teeth 20.1 and rotor surface 2.11 (see Figure 1) which is maintained by precise machining of the housings 5 and 6, bearing housings, rotor shaft 2.23, rotor field poles 2.123, and accurately punched stator laminations 20. This precision aids in equal flux distribution in the assembly of laminations 1.1 and the reduction of pole pulling of the rotor poles 2.12.

[0128] Both the front and rear housings 5 and 6 include a peripheral flange (see 6.2 on rear housing 6 in Figure 1) on their rear and front rims respectively (peripheral flange in front housing 5 is not visible in Figure 1) to locate and support the wound stator 1 centrally in the assembled housings 5 and 6. The inside diameter of the flanges are slightly larger than the outside diameter of the stator 1, so that the stator 1 can be clamped between the front and rear end faces of housings 5 and 6, all held together by four long screws 7 (of which only one is shown) which pass through channels 6.1 in rear housing 6 and apertures and housings 5.1 in the front housing 5.

[0129] The set of slip rings 8 is mounted on the shaft 2.2 of the rotor 2. Once the shaft

2.2 and the rotor 2 are rotatably mounted in the housings 5 and 6 a cooling fan 9, a drive pulley 10, appropriate spacers 2.16, spring washers 2.12 and a locking nut 2.15 are all assembled to complete the assembly of the alternator 100.

[0130] The rear housing 6 is designed to allow the brush holder and brushes of 13 to be inserted within the rear housing 6 so as to make contact with the slip rings 8.

[0131] Both front and rear housings 5 and 6 have respective apertures 5.3 and 6.3 therein through their respective front and rear faces to allow cooling air to be drawn through the alternator 100 by the front mounted fan 9.

[0132] These are the main components of the alternator 100, and it will be appreciated that there are other minor components which are known to the person skilled in the art and are thus not described in this document.

[0133] The stator laminations 20 are preferably laser cut with their shape being as indicated in figures 2 and 3. However, in production, the laminations can be stamped. Each lamination 20 is comprised of a series of teeth 20.1 and slots 20.5 which extend radially inwardly of the circular periphery 20.3. The teeth 20.1, as is better seen in Figure 3 terminate with circumferentially directed projections 20.4, which assist in keeping the windings which pass through the spaces or slots 20.5 firmly located on the assembly of laminations 1.1.

[0134] Each lamination 20 has a series of twelve trapezoidal shaped ridges 20.6 extending radially outward from the circular periphery 20.3. The ridges 20.6 serve several functions. They firstly provide a location for welding adjacent laminations 20 together. They secondly allow the stator 1, when all laminations and windings 1.2 are assembled, to be located and held in the front and rear housings 5 and 6 when appropriate notches, (not shown) are provided in the rims of housings 5 and 6. Their third purpose is to ensure that the circular rim of the assembly of laminations 1.1 is continuous. Prior art laminations have deep grooves whose concavity extends radially inwardly from the circular periphery 20.3. This concavity disrupts or interferes with the magnetic paths which can deleteriously affect the operation of alternator 100. Their fourth purpose is that the ridges 20.6 will allow extra heat fins as shown at 2.30 in Figure 2 to be attached if needed. The additional cooling fins can project through slots in the housings 5 and 6. A fifth purpose is to attach an enclosed terminal box/case if required.

[0135] Any appropriate lamination production process can be utilised to produce the laminations 20, including punching, which will not need to have the insulation repaired prior to assembly, unlike laser cutting.

[0136] The finished individual laminations 20, if they are laser cut, are deburred, reinsulated (punched laminations will not need this procedure) and then stacked making certain that the ridges 20.6 and central bore are in alignment, clamped or pressed together, and TIG welded along the ridges 20.6 or nodes created on the outer periphery 20.3 of each circular lamination 20, thus holding them together to form the completed stator stack assembly of laminations 1.1. See Figure 1.

[0137] The ridges 20.6 or nodes when they are all assembled, act as a position locator.

The ridges 20.6 or nodes are received in a notch formed in the front and rear housings 5 and 6 for location purposes. This locating function gives an advantage to the alternator 100 during assembly whereby they facilitate the positioning of the leads of the windings and so that they protrude in the correct position through the rear housing 6 for termination on the terminal board.

[0138] The internal edges 20.7, 20.8 and 20.9 of the laminations 20 (see Figure 3) which bound the spaces or slot 20.5 were insulated to prevent short circuiting of the electrical conductors and made ready for the windings.

[0139] The alternator 100 as described above is designed to operate in a high frequency range, between 400 and 800 Hz. The rotation speed of the shaft 2 is expected to be of 4000 to 9000 RPM, in order to produce the high frequency output. Generating electricity at this frequency helps to reduce the physical size and weight of the alternator 100. Tests carried out on lamination stacks at this high frequency, have revealed the problem of heat that is increased within laminations ranging from the size of 0.8 to 1.2 mm in thickness, by the generation or production of eddy currents which circulate within the lamination material and is very evident when using material from 0.8 mm and greater in thickness.

[0140] When the stator 1 is wound with main windings MW, control windings CW and auxiliary windings AW, the windings are produced by the use of relatively small diameter, insulated, parallel copper conductors to produce the required multiphase coils wound within the insulated laminated stator slots 20.5. The use of relatively small diameter conductors, help to increase the surface conductivity or skin effect to improve the efficiency of the alternator 100. An advantage of a smaller diameter conductor is the space factor improvement when the conductors are laid into the stator slot 20.5. Accordingly, the conductors pack better in the available slot space.

[0141] The windings MW, CW and AW that are provided in the alternator 100 were designed for maximum current ,taking into account the open circuit voltage needed to start the welding arc, in this particular case this voltage was a maximum of between 58 and 74 volts DC

measured without load and is within the current Australian Standards. However, a wider range of starting voltages can be applied.

[0142] The three sets of multiphase windings MW, CW and AW used in this embodiment, were constructed as follows: main winding MW: is made from three 0.85 mm diameter wires in parallel, and one wire of 0.8 mm diameter C220 electrical conductors (the C220 designation refers to the temperature to which the wire is rated, in this case 220 C); control winding CW: is made from 2 parallel windings of 0.75 mm diameter C220 electrical conductors and 2 parallel windings of 0.71 mm diameter C220 electrical conductors; and auxiliary winding AW: is an optional winding to supply power for the use of power tools with a converter or power to operate lighting, charging of batteries etc which if used can be done by a winding of 0.6m diameter of Cl 80 wire. The windings are diagrammatically shown in slot 20.5 in Figure 40 with a wedge in place. Should this winding not be required it can be eliminated, and thus reduce the weight of the combined unit.

[0143] In an alternative embodiment described below, the auxiliary winding AW is not used and the main windings MW are used to provide battery charging and is exemplified diagrammatically in Figure 41.

[0144] While C220 rated conductors were utilised, due to the inventive design of the alternator 100 which help to reduce the heat produced therein, C180 conductors, that is insulated copper conductors rated to 180 degrees Celsius could be used as the heat generated would be well within the rating of Cl 80 conductors.

[0145] The conductors or wires used in the main windings MW and control windings

CW are wound in parallel, with care taken to ensure that the same number of turns is used for each winding. The coil ends are identified for later connection. The required number of coils were fitted to the stator laminations slots 20.5 after being insulated with high temperature insulation, and held into position with insulated wedges (not shown). The coils as illustrated in Figure 7 are connected and the ends of each phase brought out along with two neutral wires 80, 81, in Figure 6 from the independent star point connections 83, 84, 85 to be terminated on the terminal disc at the rear of the back endplate. The winding was then bound and pre-tested, before varnishing and baking.

[0146] The main winding MW being MPHl, MPH2, MPH3, is made from two high output power electrical windings which are parallel star connected as is illustrated in Figure 7. A delta connection was not used as this type of connection can exhibit a circulating current within the closed loop winding. The control winding CW being CPHl, CPH2 and CPH3 used in the

alternator 100 is also connected in star configuration as also illustrated in Figure 7. The optional auxiliary winding AW, being APHl, APH2 and APH3 if utilised is also formed in a star connection.

[0147] As is illustrated in Figure 7, neutral leads 80 and 81 are provided and connected to the star points 83 and 84 in both the main and control windings.

[0148] The insulation used in the alternator 100 is of a high temperature grade.

[0149] All the connections of the copper conductors within the stator are preferably silver soldered or fused, or welded rather than crimped. This is because the use of crimping causes a reshaping or squashing of the copper conductors and this can cause difficulties due to the high frequency operation of the alternator, and preferably not used. Silver soldering can be used to provide a good all round joint of the copper conductors, and is preferably used for the joining of the coil ends to flexible cables to convey the high frequency supply to the main bridge rectifiers.

[0150] If required a heat detection device such as a klixon or micro temperature switch, commonly called a microtherm, of nominated operating temperature and current rating can be imbedded and bound into the main windings MW, control windings CW and auxiliary windings AW to detect over temperature of these windings. A second Klixon or microtherm of a lower detection temperature can be used to indicate early warning in control winding CW before it shuts down power to the rotor fields. A third Klixon can be used on the heat sink 415 containing the rectifiers 208(Figure 4), 230 (Figure 23), 232 (Figure 24), 233(Figure 25).

[0151] Klixons or microtherms are available in a number of operating heat ranges from

90°c to 140°c or higher. For the alternator 100 a microtherm operating at 140°c was selected, which is well under the insulation capabilities of the conductors used in the main windings MW, control windings CW and auxiliary windings AW (if used). The conductors used in the stator windings (being all the windings MW, CW and AW (if used)) are of class "H" and C220 wire, which means they are rated up to 220°c . Thus a 140°c microtherm is well within the rating of the conductor's insulation.

[0152] The 140°c microtherm 313 is wired in series with the rotor positive supply line, see Figure 4, so that should the main windings MW exceed the Klixon or micro temperature switch operating temperature then, the switch will open circuit the excitation power to the rotor field winding, thus reducing output current which would normally flow from the main windings MW to the main diodes and the supply IB or 1C to the controller module. This will cause green LEDs on the main control panel to be extinguished, whilst a red LED will be illuminated.

[0153] When the temperature drops to a safe level the microtherm switch will close the excitation circuit and then current will be restored via an automatic restart circuit through a no volt relay 60 which is best illustrated in figures 5 and 11.

[0154] The alternator 100 includes another protection system. This system allows the lamination assembly 1.1 to saturate should a welding rod "stick to the job". This saturation will cease current generation thereby causing a loss of welding power to the welding rod until the rod is freed from the welding job. Then the no volt relay 60 of Figure 5 or 11 will activate the start circuit restoring welding power at the original power setting.

[0155] Control winding CW, being the lower output three phase winding is connected along with the star point 83, 84 by neutral leads 80, 81 to the common input of the rotor field control board as in Figure 5 or 11.

[0156] Single phase power, that is, one phase emanating from any one of terminals of phases MPHl, MPH2 or MPH3 and the star point junction 83 or neutral lead 80 of the main winding is used to start the self excitation feature of the alternator 100, and is controlled by the no volt relay 60 on the electronics circuit board. Anyone of the finish leads of MPHl, MPH2 or MPH3 is connected to terminal 515 on the circuit board of Figure 4 on the electronic controller 200.

[0157] As earlier stated, a second lower temperature Klixon or microtherm could be used if desired and can be connected to a power source and a orange LED or to a sound warning device to give a visual or audio early warning that the alternator 100 is running close to thermal shutdown and that welding should cease allowing the cooling fan 9 of Figure 1 to drop the temperature of main windings MW, and control windings CW until the Orange LED is extinguished.

[0158] To lock the main windings MW and control windings CW into place in the lamination assembly 1.1, the whole of stator 1 (assembly of laminations 1.1 and stator windings MW, CW and AW if present) is varnished and then baked. This aids in the protection of the electrical windings and insulation from outside contaminants, dust, fluids and other foreign bodies.

[0159] As the alternator 100 will be used in variety of conditions which may include, dust, moisture, oil, grease, fungus, and in atmospheres varying from very low temperatures to tropical and possible desert heat conditions, the choice of varnish or protective coating needs to be carefully considered. The stator 1 of the alternator 100 is preferably coated in an epoxy resin

coating based finishing varnish. If desired or required an anti- fungal coating may also be employed if used in tropical areas.

[0160] The control circuit and arrangement is illustrated in figures 4, 5 and 6. The controller 200 makes use of a positive regulator 210 made by National Semiconductor and is capable of medium output current, has internal thermal protection along with short circuit protection and is adjustable from 30 volts down to 1.3 volts. A voltage trim pot 209 on the regulator can set the maximum voltage to 13 volts, so that the rotor voltage is not exceeded when setting the weld current from the variable resistor or potentiometer 205 on the main panel (or remote control if used). The power to operate the electronic controller is derived from the low power control windings CW and neutral 81 in the stator 1. This high frequency alternating current from control winding CW is rectified by the three phase rectifier diodes D2, D3, D4 (figures 4 and 5), smoothed by capacitor Cl (Figure 5) and controlled by a variable voltage regulator 210 (Figure 5). The output from the regulator is filtered and protected from reverse power by a high powered diode D5 (Figure 5) and a fuse 201. From this point the output regulator power is connected to the rotor field coil 203 via sliprings 8 (Figure 1). The circuit connects to the fields of the rotor via a main start switch 207 (also referred to as the rod change switch because during welding not activating this switch allows a spent welding rod to be replaced by an unspent welding rod). The rotor receives only direct power thus avoiding the generation of excess eddy currents which would otherwise heat the rotor. A high voltage protection diode D8 (Figure 5) is connected across the field windings 203 for circuit protection in case of an abrupt power loss, which can cause a rapid field collapse that can generate a high voltage back into the circuit.

[0161] The adjustable regulator 210 is controlled by variable resistor or potentiometer

205 connected to the adjustable pin (adj) of the regulator 210.

[0162] The input and output power availability is indicated by solid state light emitting diodes 206, 204 which indicate the presence of power.

[0163] The variable resistor or potentiometer 205 is fitted with a pointer dial so that it can be positioned to a calibrated scale for the size of rod to be used or fine setting the weld for the thickness of metal being welded. Variable resistor or potentiometer 205 is also used should TIG be selected by switch 211 Figure 5.

[0164] The controller has total control of the rotor flux, and the output (assuming constant prime mover speed) of the alternator 100.

[0165] There are three switches located on the front main panel, as is illustrated in

Figure 6. They include the slider switch 211 for selecting ROD or TIG welding; the rod change or main start switch 207 and or, if used, a "Manual or Remote" change over switch 27.

[0166] The handle (such as that illustrated in Figs 17, 18, 19) can be directly wired to the control panel. Alternatively the controller can include a multi pin plug (not shown) that allows a welding rod handle fitted with a rod change or main switch 207 and remote Power/Current control 205 to be accommodated. This allows rod changing without the power being supplied at the handle and setting up the welding rod in hard-to-get-at situations without accidentally arcing the rod. When the rod is in position the remote rod change or main switch 207 can be closed thereby energising the welding rod. The power or current control by remote variable resistor or potentiometer 205 can be set to the required rod being used. To activate this facility the user will toggle the remote, manual change over switch 27 on the control panel to the "Remote" position.

[0167] The arrangement shown in Figure 5 illustrates a circuit suitable for start-up of the alternator.

[0168] A main or control winding is connected to terminal 515 which is connected to the normally closed contact of no-volt relay (NVR) 60, and from thence to the rotor field winding 203.

[0169] A second power supply to the rotor winding is derived from the stator windings, such as the control winding, via diodes D2, D3, D4, regulator 210 and diode D5. Diode D5 prevents excess voltage from main winding 515 reaching the regulator 210 outlet. However, the regulator requires a finite input before it can produce a useful output. Thus the start-up circuit is adapted to provide input for the field winding while the regulator does not produce a useful output.

[0170] The control inputs of the no-volt relay 60 are connected to the output diodes (eg,

208 in Figure 4) via Rl and ZDl .

[0171] As the rotor is spun by the engine, the residual magnetism in the rotor and stator is caused to fluctuate as the reluctance of the magnetic path varies due to the rotation. This induces a voltage in the stator windings and current is fed to the rotor field winding 203 from the stator winding connected to 515.

[0172] When the voltage across the power diodes 208 is sufficient to trip the no-volt relay, the normally-closed contacts open, and the output from the regulator 210 then supplies the rotor winding.

[0173] Figure 11 illustrates an alternative circuit suitable for start-up of the alternator in a circuit adapted for TIG welding.. Because TIG welding requires a high voltage (-1.5 kV), it is necessary to ensure that this voltage is not fed to the control IC 210 or the no volt relay 60 control input.

[0174] A stator winding is connected to the terminal 515, and thence to the normally closed contact 8339 of no volt relay 60 via diode Dl and power limiting resistor PRl. The no volt relay 60 output is connected to the field winding 203 via start switch 207.

[0175] In this embodiment, the no volt relay control input is derived from the control winding, for example from the input sides of D2 and D3 as illustrated into the rectifier REC. Alternatively, the connection can be to the output sides of D2 and d3, and rectifier REC can be dispensed with. The sensing voltage is fed to the no volt relay 60 via Rl and ZDl . Thus, when the sensing voltage exceeds the no volt relay trip voltage, the normally closed contact 8339 opens, and the rotor field winding is supplied by the control circuit via the output of regulator 210.

[0176] The arrangement illustrated includes a start-up circuit powered from one of either the main windings MW or control windings CW of the alternator. Diode Dl (figs 5, 11) is connected via a current limiting resistor PRl to the no volt relay 60, which is connected across the main welding power rectifiers 208 (see Figure 4) via ZDl and Rl. In the absence of actuation of the no volt relays 60 by output from the main rectifiers 208, normally closed high current contacts of the no volt relay 60 connect Dl and PRl to one side of the rotor field winding 203 to provide starting excitation. For this purpose the star point 83 of the main windings MW is connected to the common side of the rotor field winding 203 together with the star point 81 of the windings CW.

[0177] Once the supply of operating voltage is detected the no volt relay 60 is activated, and the high current contacts open the start circuit.

[0178] The alternator 100 is furthermore designed so that upon short circuit of the output of the main rectifiers 208 under operating conditions, the stator lamination assembly 1.1 is momentarily fully saturated, resulting in collapse of the rotor field to the extent that the controller is no longer powered by the control windings CW, therefore no current is supplied to the welding rod.

[0179] This is particularly useful in the case of a stuck welding rod, which upon collapse of the welding current can be released from the metal without arcing and overheating or destroying the rod and without and possibly causing damage to the stator main windings MW.

[0180] Once the rod is freed, and the no volt relay 60 has closed the start circuit, the alternator 100 will begin supplying current for welding at the original current setting. As earlier stated, provision has been made for the welding rod handle with in-built control wiring to be on a separate plug which can be removed if the main welding cable is faulty and a new cable is fitted to the welder. The rod change or main switch 207 along with the remote current control 205 is simply plugged into the provided controller socket (see Figure 4) without the need to re-solder or make screw connections.

[0181] Alternators of the prior art have their field system controlled by an on-board voltage regulator and also need a battery as a voltage reference and load. This was not suitable for an alternator which is to be used for welding which requires total control of the rotor field flux in relationship with the generated stator output voltage to the high powered rectifiers to obtain a correct level of arc voltage for proper flow of the selected welding rod to the metal.

[0182] In the alternator 100, the carbon brushes 13 of Figure 1, that make contact with the slip rings 8 are isolated from each other and not connected to any voltage regulator device, other than the controller of figures 4, 5, 10, 11 and 26. Polarity of the brushes 13 is of no importance for the alternator 100 when it is used in the welder application. The sliprings can be connected to either positive or the negative terminal board connectors - as the diode D8 of figures 5 and 11 is a permanent connection to the PCB. The diode D8 is a freewheeling diode, so that if the field collapses, the diode D8 will conduct the electrical energy from the coil within itself. In the preferred embodiment it does not matter what polarity is present at the brushes because the plug that comes from the board is set up for the polarity. Nor is any of the slip ring brushes connected to any part of the metal housing of the alternator or prime mover. They are separate and isolated.

[0183] The alternator 100 includes high power diodes, (bridge rectifiers 208 of Figure

4) suitable for use when the alternator 100 is used in a welding application. The diodes are mounted to efficient heat sinks 415 to dissipate the heat from the diode junction, which can be quite significant when welding with settings at high current levels. Quality high voltage rectifier diodes are used in view of possible spikes that may be present at the junction of the diode.

[0184] The high power diodes 208 are high voltage/large current carrying diodes for example, 400 volt 85 amp units. From tests carried out these were found to be electrically satisfactory and well within the heat tolerance specifications for the diodes.

[0185] Two heat sinks (415) with heat dissipating fins are used, each carrying three diodes for positive and negative supply lines. The main windings MPHl, MPH2 and MPH3 are

connected to the diodes which form a three phase bridge rectifier 208. The welding cables are connected to the terminals on the heat sinks 415 for the DC output. The cables of suitable size are connected to the terminals to convey the power to the welding rod handle and earth or common clamp.

[0186] At the same point of connection are the cables that supply the presence of DC voltage signal to the no volt relay 60 detection circuit as earlier explained.

[0187] The output of main winding MW is connected to the three phase bridge rectifier

208 which is preferably made up of a number of high power silicon diodes mounted directly on appropriate heat sinks 415 to which welding cable terminals are fitted. However, other forms of bridge rectifiers can also be used to obtain the direct current output for welding, as is described later.

[0188] Also connected to the heat sinks 415 are the no volt relay 60 cables which go to the electronic control panel 200.

[0189] The direct current which can be in excess of 120 amps, from the main rectifiers

208 contains a high frequency ripple on top of the DC output. This ripple, depending upon the number of poles used and the speed at which the alternator is rotated (which is governed by the speed of the prime mover PM or motor means), aides in the starting of the arc and the resultant weld.

[0190] The alternator 100 is self excited, without need for a battery power source to supply power to the rotor fields or electronic controller. The alternator 100 supplies power from itself to start up using the residual magnetism in the magnetic flux circuit. External excitation can be used in case the residual magnetism is insufficient for this purpose.

[0191] The alternator 100, during start up is a magnetic field flux amplifier to provide power to the main rectifiers 208 and no volt relay 60, which switches control from the start up circuit to controller 200 to obtain controllable power for the welding rods.

[0192] In order to maintain the appropriate operating temperature, the alternator 100 includes the fan 9 (in Figure 1) fitted to the drive end of the alternator 100, and is located behind the drive pulley. This fan causes low pressure within stator 1 causing cool air to be drawn through the centre of the alternator 100, thus cooling the surrounding copper conductors and laminations along with the rotor winding. Due to the fan construction warm air is forced away from the alternator 100. If desired, a fan can be positioned on the rear to blow air through the alternator 100, rather than drawing air through as in the case of a front mounted fan.

[0193] As shown in Figure 5, a fuse 201 is installed on the controller along with a thermal circuit breaker 202 and field commutating diode D8 to prevent s pike damage to the rotor field in case of an abrupt open field current collapse. The fuse is to protect the controller 200 in the case of a field short circuit.

[0194] Another capability or feature of the welder is that it is capable of TIG welding which is selectable by a switch 211 located on the control panel (see figures 5 and 6) with fine current control available from variable resistor or potentiometer 205 and it's pointer knob and scale located on the front panel of Figure. 6 of the controller to set the TIG welding power. The TIG arc is started by striking the rod to the metal to be welded, which in welding terminology is called a cold start. Whilst this works, it has its limitations, due to rod stick and other difficulties but these are addressed by the welder features discussed below.

[0195] Indicators on the controller front panel are two light emitting diode indicators: a green LED for power availability coming from the alternator 100; a red LED indicating power to the salient pole fields (the rotor); and an orange LED (optional) for the early warning of temperature rise in the stator winding and/or the rectifier heat sinks 415.

[0196] On diode heat sink(s) 415 there is a thermal micro switch (Klixon) or microtherm. This is in series with the alternator stator Klixon and if either is activated the red led will be illuminated, at the same time a power reduction will be initiated until the temperature is reduced, eventually resulting in a return to full operation.

[0197] If desired, either electronic or analogue voltage or current meter(s) can be incorporated into the panel layout for monitoring the operational requirements for TIG welding. However, such meters can be readily damaged when subjected to vibration and/or breakage. Therefore solid state indicators are preferred as they are more rugged.

[0198] Another alternative to metering is that of calibrated scales on the main panel for setting the amount of DC field power to the rotor fields by positioning the adjustable point to a required location on the scale. A number of scales can be used, in this case two, they being one for stick or rod welding and a second for TIG welding.

[0199] Should the alternator 100 stay in the start up mode upon excitation, the operator can slightly increase the dial setting a small amount so that the regulator controls the rotor flux and thus stabilises it.

[0200] Figure 8 illustrates the circuit of a battery charger in accordance with an embodiment of the invention.

[0201] The battery charger is adapted to charge battery 750. Power is drawn from a main windings MW (MPHl, MPH2, MPH3) or a transformer driven there from, and is rectified through bridge rectifier 742. Filter elements and regulator elements (not shown) can also be included. One input terminal of the rectifier 742 is connected to the active side of one phase of the main winding MW, in this case MPHl . The other input terminal of rectifier 742 is selectable to either the neutral lead 80 or to the active side of a second phase of the main winding MW, in this case MPH3, via relay switch 740 which can alter the voltage applied to the rectifier 742. This gives the battery charger the ability to charge batteries of different voltage ratings.

[0202] The battery charging feature can be an alternative mode of operation of the alternator from welding or TIG welding. A master switch 710 provides options of welding, charging a battery of a first voltage (e.g., 12 v), or charging a battery of a second voltage (e.g., 24 v).

[0203] Master switch 710 is used to select the "weld", 12v, or 24v options. Operation of this switch also switches switch 728. When the switch 710 is switched to the 12v position, diode 718, relay coil 722 and resistor 724 are connected to the DC input of controller 200. At the same time, switch 728, which is ganged with switch 710, connects resistor 732 and trim pot 734 to the adjustable input of controller 200 to cause it to control the rotor flux coil 203. Relay coil 722 controls relay switch 744 and closes these contacts. Relay coil 714, which controls change-over switch 740, is not activated when the 12v position is selected, and relay switch 740 connects the neutral lead 80 to rectifier 742 in this state. Thus a single phase voltage is applied to the rectifier inputs.

[0204] Switching switch 710 to the 24v position connects diode 720, relay 722 and resistor 724 to the DC input of controller 200. This sets the bias input to cause controller 200 to control the rotor field coil current through coil 203 at the appropriate level for charging a 24v battery. In addition, relay coil 714, resistor 716 and diode 712 are also powered from the same source. Thus relay coil 722 again closes relay contacts 744, and, in addition, relay coil 714 causes change-over contacts 740 to connect the output of phase MPH3 to the input of the rectifier 742. Thus the input to the rectifier is now a two phase input.

[0205] Switch contacts 744 additionally provides isolation for the charging terminals when the charger is not in use.

[0206] Green diode 752 and red diode 754 provide an indication of when the battery is connected correctly (diode 752 will glow green) or incorrectly (diode 754 will glow red). The

battery should be connected before the switch is switched from the "weld" position so that the diodes 752, 754 can indicate correct connection of the battery.

[0207] A fuse 746 provides protection from excessive current.

[0208] In the "weld" setting, welding power can be controlled by potentiometer 205.

[0209] The current flowing into the battery 750 can be sensed by a current sensor or voltage sensor (not shown) and this can be applied to controller 200 to regulate the rotor field current to maintain charging within preferred limits.

[0210] Preferably, the battery charger is a plug-in option in which the link 726 is replaced by a connection to the battery charger module.

[0211] Some of the benefits of the alternator 100 include: it can be used as a normal welder using standard rods up to 3.2mm with this model; it can be used as a TIG welder - as provision has been allowed for in the design; it can be used as a lighting power source; it can be used as a battery charger; it can replace regular car alternators; it is lightweight and portable; it is normally powered by (but not limited to a) single groove pulley drive from a prime mover; and with the addition of a small converter it can power standard small angle grinders or drills.

[0212] While alternator 100 can be installed on a vehicle and can replace the regular alternator it can also be mounted on a frame or base with a 4 stroke or 2 stroke engine of a relatively small size to produce a portable and lightweight welder. The size of the engine and the belt drive fitted, needs to provide approximately 4000 to 9000 RPM at the rotor shaft 2, but most preferably between 6000 RPM and 7000 RPM. It is expect that the combined mass of a small engine and the alternator 100 will be approximately 45 kilograms. Other prime movers could be used to drive the new alternator these could include for example; steam turbine or engine, wind, water or hydraulics plus AC and DC electric machines.

[0213] It is important that in the preferred stator windings, the "start" and the "finish" of each group of coils needs to be noted because failure to correctly connect them may result in incorrect operation of the windings. This will result in a low output or failure to control the alternator 100 properly.

[0214] The inventor has developed a 3 -phase winding (Figure 16) and a 6-phase winding (as illustrated in Figure 14 and 15) in alternators built in accordance with embodiments of the invention. Both stators wound in accordance with figs 14 and 15, or 16, could be used for rod or ARC welding and TIG welding plus Battery Charging.

[0215] The 3 phase main and control windings of Figure 16 is a 120 ⁰ E ( electrical degrees i.e. 120° phase displacement), three phase winding to supply power to a three phase power bridge rectifier 230 (as illustrated in Figure 23), used for the rectification of the alternating current supply to direct current for the purpose of welding. It will be noted in Figure 23 that the rectifier 230 is mounted on heat sink 415. In Figure 16 only phase MPHl of the main winding MW and phase CPHl of the control winding CW is illustrated, and the other phases, respectively MPH2, MPH3 and CPH2, CPH3 are constructed in the same manner as that illustrated in Figure 16 except for a phase displacement of 120°.

[0216] Figure 23 is a vector diagram showing supply to a block three phase power bridge rectifier 230, with a current detection transformer circuit 2211 in one phase. It will be understood by the reader that three single phase bridge rectifiers or a single diode arrangement can be used in place of the block single unit 230.

[0217] From Figure 16, it can be seen that there are three groups of coils, 1, 2 and 3 of two coils consisting of 11 turns of copper wire for the MW and 8 turns of copper wire for the CW, wound in series with a start SM and finish FM for main winding leads, and a start SC and finish FC for control winding leads as discussed below.

[0218] In this case the finish lead FM of the three groups are connected to a common point called a Star (or neutral) point 83 . This Star point 83 also is common to the other finishes FM of the other two main winding phases MPH2 an MPH3 (not illustrated). A flexible lead is also attached to the Star point 83 and brought out to the main controller (see item 80 in Figure 4, 5, 10, 11 and 26).

[0219] The start leads SM of the main winding phase MPHl of each group of coils have a common connection and terminate at MPHl and are joined to the bridge rectifier 230 as in Figure 23. Likewise with the other two phases MPH2 and MPH3 with one phase running through the current detection transformer first then rectifier 230. A single connection 513 from one of the three phases (in this instance the MPHl) is used as illustrated in Figure 16 to connect to the start up terminal 515 on the controller 200 as illustrated in Figure 4,5,10,11 and 26.

[0220] Total number of leads from the main winding is 8, consisting of three main winding leads being one for each phase (MPHl, MPH2, MPH3) to the bridge rectifier 230 or 232 or 233, with one phase running through the current detection transformer. 3 control winding leads (being CPHl, CPH2, and CPH3), a start up lead, and one neutral lead from the Star point 83 to the controller. The windings are spaced for 120°E around the stator laminations.

[0221 ] The control windings CPHl , CPH2, CPH3 which are wound on top of the main windings MPHl, MPH2, MPH3 as earlier described for supplying the power for the control and other electronic systems, along with power for the salient pole rotor 203, as it has been found electrically beneficial to have the electrical conductors as close as possible to the magnetic rotor surface.

[0222] For the 6 phase system the phases MPHl , MPHlA, MPH2, MPH2A, MPH3,

MPH3A (as also illustrated in figs 24 and 25) are the outputs of the main windings MW and are connected to three single phase high power bridge rectifiers 232 in Figure 24, supplying the required direct current output for welding. Alternatively as illustrated in figures 25, the output phases MPHl, MPHlA, MPH2, MPH2A, MPH3, and MPH3A can be connected to two 3 phase high power block rectifiers 233. In respect of the rectifier arrangements of figs 24 or 25 appropriate heat sinks 415 need to be utilised as indicated in broken line figures 24 and 25.

[0223] Figs 24 and 25 show a vector diagram of the six phase arrangement with bridge rectifier connections and main current detection transformer 2211 on one phase, in this case MPH2A.

[0224] The six phase arrangement will be described with reference to Figure 15 to one phase each of the dual windings referred to as MPHl and MPHlA (see also Figure 14). Phases MPH2, MPH2A and MPH3, MPH3A are similar to the MPHl and MPHlA phases.

[0225] As illustrated in Figure 15, main winding phase MPHl and MPHlA, consists of three coils of seven turns each of copper wire wound in series and are placed 120°G (geometrically) around the lamination assembly 1.1. Phase MPHl has main winding start point SM and finish point FM for its leads, while the main winding phase MPHlA is placed halfway between the space left by the placement of the MPHl windings That is at 60°G, and as it happens these windings are electrically 60°E between phases. The MPHlA windings also have main winding start points SA and finish points FA for its leads.

[0226] The use of high frequency operation derived from a multi-pole rotor and high rotation speed reduces the number of turns of copper wire wound on the coil required to generate a required output.

[0227] The finishes FM and FA of leads of both windings MPHl and MPHlA are connected to a common point called a Star point 83 with a common flexible lead 80 (neutral) brought out to the main controller (see item 80 in Figure 11).

[0228] The start points SM and SA of windings MPHl and MPHlA are made via an appropriate lead out to the bridge rectifiers 232 or 233 of figs 24 or 25.

[0229] A control winding CPHl , illustrated in Figure 15 as the smaller broken line is shown wound over the MPHl winding only. The number of turns of copper wire per coil is as follows. 7, 6, 6. These coils are connected in series and not wound over the MPHlA winding. The control winding CPHl has, its finish FC terminating at star point 83 whilst its start goes to D2 (see Figure 4, 5, 10, 11, 12) on main controller 200. Control windings CPH2 and CPH3 are connected and wound similar to CPHl. CPH2's start connects to D3 and CPH3's start connects to D4 both of controller 200. The finish points of CPH2 and CPH3 are connected to star point 83. See previously mentioned figures.

[0230] An extra lead is attached to either of any main winding phase (MPHl , MPH2 or

MPH3) lead for start up as described earlier in paragraphs in relation to the three phase arrangement.

[0231 ] The total number of flexible winding leads exiting the alternator with six phase windings is 11, being six for the main windings (MPHl, MPHlA, MPH2, MPH2A, MPH3, MPH3A), 3 control windings (CPHl, CPH2, CPH3), one start up lead and the neutral lead 80 to the controller 200.

[0232] Flexible leads from the outputs of phases MPHl , MPHlA MPH2, MPH2 A,

MPH3, MPH3A of main windings to the bridge rectifiers 232 (Figure 24), 233(Figure 25) are used to help reduce or eliminate work hardening of the copper conductors due to vibration of the motor or prime mover engine.

[0233] Figure 40 and Figure 41 show how the windings lay in the lamination slot. It can be seen that the main winding is layed in first followed by the auxiliary winding (if used) lastly the control winding held in by a wedge or thick insulation shaped as a wedge. Upon completion the winding is varnished and baked.

[0234] As stated above thermal switches can be placed into the main winding MW for the protection of these windings. This thermal switch 313 in the main winding is in series with a heat sink micro therm (klixon) 2617. Should the winding or heat sink 415 over heat then the thermal switch will operate and a red light emitting diode (LED) will be activated on the control panel and will also cause the alternator to reduce its output as later described.

[0235] A single or bank of capacitor(s) 231 of suitable size and voltage rating, when connected in series or parallel, and when fitted to the output of the rectifier 230 (Figure 23) or 232

(Figure 24), 233(Figure 25) (Figure 24 or 25) aid in the stability of the arc produced by the welder and also helps to filter the direct current output for welding.

[0236] Illustrated figures 9, is a TIG start up circuit. This can be considered to comprise

4 main parts: a regulator 8300; a main oscillator 8400; a high voltage multiplier 8200 and a voltage doubler of 8100, (or tripler 8500 of Figure 36; or triple 8700 of Figure 37; or doubler 8800 of Figure 38; or doubler of Figure 42)

[0237] The regulator 8300 is comprised of regulators REGl and REG2 and is described with reference to Figure 9.

[0238] The REG 1 is an LM350T 3 Amp or LM338T 5 Amp regulator and makes up a first part of regulator 8300 to provide a variable positive supply, adjustable over 1.2v - 32v, with overload shut down. The direct current input to the regulator 8300 is derived from the voltage doubler 8100 which converts the supply from the control winding CPHl in the alternator.

[0239] Both regulators REGl and REG 2 need no explanation of operation for a person skilled in the art. For the purposes of the invention, the direct current output voltage to supply the oscillator circuit 8400 is preset to a nominal voltage by adjusting the variable trim resistor 8315 in the regulator circuit 8300.

[0240] The circuit of Figure 9 produces a high voltage so as to start the welding arc for

TIG welding.

[0241] Regulator REG 1 supplies power to drive transistors in the main oscillator 8400.

Whereas the regulator REG2 stabilizes the 555 IC timer 8555 supply to 12 volts.

[0242] The timer 8555 drives transistors Ql and Q2 alternately. Transistor Ql charges the capacitor 8411 via the transformer 8413 and transistor Q2 discharging the capacitor 8411 into the transformer 8413. Capacitor 8415 reduces the power consumption and increases the output voltage. The output of the transformer 8413 is fed into the voltage multiplier 8200 and according to the number of diode / capacitors stages included in the voltage multiplier circuit, the voltage output is increased.

[0243] The transformer 8413 has a 12.6 volt centre tap secondary and a 150mA 240 volt primary. The oscillator 8400 drives the centre tap of the "secondary side". The primary 240 volt side is connected to the voltage multiplier 8200. The frequency of the oscillator 8400 is variable by means of trim pot 8417 from 683 Hz to 3480 Hz. Most small "off the shelf 50Hz transformers will work satisfactory at a frequency of 1200 - 1500 Hz and would be suitable in this application.

[0244] In the circuit of Figure 9 relay RLY7 short circuits the high voltage multiplier circuit 8200 to prevent accidental shock from the starting circuit of Figure 9 should the TIG handle be left lying around. Short circuiting of the high voltage will not harm the electronics as the circuit is designed to handle this situation.

[0245] The voltage multiplier 8200 is used because high voltage is required but only low current drain is desired. The primary side "P", (the 240 volt side) of the transformer 8413 is connected to the input of the "cascade" multiplier 8200 to produce the required high voltage to start the weld arc. The capacitor value and diode ratings are determined by the required output current. The Capacitors are rated at 3KV and the diodes at IKV, each being well within the service requirements to produce high voltage to start the welding arc which is no more than 1.5KV. The high voltage output can be adjusted over some 400 volts by the trim pot 8417 which is part of the timer 8555 circuit. The circuit of Figure 9 consumes approximately 180mA to 20OmA from the input power source.

[0246] As mentioned earlier, the high voltage output is across contacts of relay RLY7 to ensure that the capacitors of the high voltage multiplier 8200 are short circuited whilst TIG welding is not in use. This works in conjunction with the main controller current detection transformer 2211 in Figure 22 to shut down the high voltage output of the multiplier 8200 once the welding arc is established by opening the negative supply rail via the normally closed contacts ofRLY2 of Figure 22.

[0247] To operate or trigger the welding arc to start, the previously mentioned normally open contacts of the rod change or main start switch 207 on the main panel or its remote equivalent on the handle of the welding rod holder is closed connecting the negative supply rail for circuit operation. It is important to note that the rod change or main start switch 207 can be floor mounted, foot operated, main panel located or handle mounted. The rod change or main start switch 207 can be directly in the circuit or alternatively, it can activate a relay which is directly in the circuit.

[0248] No circuit operation or any high voltage is available until the operator presses the normally open rod change or main start switch 207 to bring the negative rail into the circuit which allows relay RL Y7 to remove the shorted contacts from across the high voltage multiplier 8200. Preferably the rod change or main start switch 207 is recessed on the TIG handle, if a remote switch is used.

[0249] In the high voltage multiplier 8200 there are three high voltage diodes 8223 connected in series to prevent the main welding current and voltage from feeding back to relay RLY7'S contacts, which would otherwise destroy them.

[0250] When the rod change or main start switch 207 (see figs 17 to 19) on the welding handle is closed, the circuit of Figure 9 will be activated. Upon the establishment of the main welding arc the current detection transformer circuit of Figure 22 will disable the high voltage circuit of Figure 9 until a restart is required.

[0251] The main winding MW is kept free of any other circuits, other than the main rectifiers 230; 232 (Figure 24), 233(Figure 25) and the high voltage multiplier 8200 when TIG welding is used, except when battery charging is selected.

[0252] All other control and electronic circuit power is derived from the control windings, otherwise components may be damaged by high voltage.

[0253] TIG welding is activated when required by switch 211 (see Figure 34) on the main panel. A second switch 815 (Figure 34) is for high and low current control which adjusts the rotor field current for the mode of operation.

[0254] In addition to the previously mentioned an adjustable field current control or variable resistor or potentiometer 205 on the main panel or on the welding handle along with the rod change or main start switch 207 makes it easy to start and adjust the finer current requirements for the weld. No matter the current selection, the amount of current for the selected range is variable by the remote control knob on the welding Handle.

[0255] To allow the mobile welder to perform low current TIG welding the starting voltage to ionize the gas to start the welding arc requires a voltage amplification to be utilised to prevent the voltage applied to the starting circuit of Figure 9 diminishing due to the selection of low current generally required for thin gauge metals. In this regard see the description below related to Figure 42.

[0256] As output of the control winding may decrease due to a low output level being selected when the current switch 815 is in the low position, a voltage doubler circuit 8100 is utilised in conjunction with a voltage stabilizer circuit 8600 consisting of a power transistor TRl and Zener diode ZDl in the base circuit of the transistor TRl . When the current switch (see switch 815 in Figure 29 and 34) is in a high position the voltage doubler 8100 is a standard rectifier connected to the voltage stabilizer 8600 and when the current switch 815 is in low current position the voltage doubler 8100 takes effect and increases the voltage output to the stabilizer 8600 thus supplying the required voltage levels.

[0257] The voltage doubler 8100 in combination with voltage stabilizer 8600 improves the power handling and the regulation of the circuit of Figure 9 by a factor equal to the current gain of the transistor TRl . The output voltage from this circuit 8600 will be equal to the Zener voltage minus the base emitter voltage of the transistor TRl (approx 0.7v): Output Voltage = Zener Voltage -0.7v

[0258] Illustrated in Figure 38 is an alternative voltage doubler circuit 8800 which can be used in substitution of the circuit 8100 of Figure 9. The circuit 8800 will provide a greater voltage output by comparison to circuit 8100 because it utilizes a second phase from the control winding CW of the alternator 100.

[0259] On occasion there will be a need to TlG weld very small gauge material and this would call for relatively small welding current control thus effecting the rotor magnetic flux that is available for the operation of the welding arc starting circuit of Figure 9. Therefore it is desirable to increase the power available to the circuit of Figure 9. This can be achieved by the use of a voltage tripler 8700 as illustrated in Figure 37, as a substitute for voltage doubler circuit 8100 or 8800 earlier described, so that the available generated voltage can increase the direct current to the high voltage oscillator section of the start up circuitry of Figure 9. The tripler circuit 8700 has a transformer which utilizes a single phase of the control winding to feed the secondary of a tap transformer providing the selectable high/low voltage from switch 815.

[0260] If desired a voltage tripler 8500 of Figure 36 could be utilized and this differs from tripler 8700 by switch 815 being able to switch between the neutral or a second phase of the control winding CW.

[0261] Because the alternator is operating in the range of 600 to 800 Hz, this means that the physical size of the transformer in tripler 8700 has to be capable of operating with this frequency.

[0262] Transformers of either isolated or auto transformers as described above are understood by those in the electrical field, so no description of transformer operation is required. The circuit of Figure 42 is the best option for this application of tig welding.

[0263] Illustrated in Figure 22, the current detection transformer 2211 detects a voltage change by transformer action. In this application the primary coil of transformer 2211 is a heavy conductor which is connected between one phase of the main winding and one alternating current input to the bridge rectifier 230, 232 (Figure 24), 233(Figure 25).

[0264] The secondary coil 2215 is connected to an amplifier circuit as illustrated in

Figure 22, in which there is an adjustment control trim pot 2217 feeding the base circuit of

transistor TRl and a relay RL Y2 in the collector circuit of transistor TRl along with a red LED indicator 2219. The first set of normally closed contacts of relay RLY2 are connected to the negative rail 8419 (see Figure 9) as previously described. When the welding arc is started the transformer 2211 detects primary current and by the transformer action, the secondary causes the transistor to conduct. This opens the normally closed contacts of the negative supply line 8419 and shuts down the supply, until a restart. This same current transformer 2211 circuit also controls the connection of the capacitor(s) across the rectifier for filtering of the direct current and weld improvement via the same relay but with a second set of contacts. 8311 and 8313 are power supply lines to the current detection circuit of Figure 22 and come from the circuit of Figure 9.

[0265] The no volt relay 60 coil circuit is preferably operated from the control winding because the circuit of Figure 9 produces high voltage on the rectifier 230, 232 (Figure 24), 233(Figure 25) and may cause problems with the controller 200 from circuit feedback if it were located in the main winding circuit. Thus the no volt relay 60 receives its operating DC supply from a small rectifier and two phases of the control windings CW.

[0266] In operation, during start up, the no volt relay 60 (also labelled RLYl on some drawings) remains in the start up position until the control windings are producing current sufficient to cause the relay 60 to energize, thus disconnecting the start up circuit of figures 5, 11, 12. The start up circuit 911 of Figure 11 is designed to allow low level rotor excitation for the TIG circuit to operate when switched to the "Low" position without the no volt relay 60 operating and bringing the alternator start up circuit of figures 5, 11, 12 on line at a high amperage level. This can cause the power resistor in series with Dl of figures 5, 11, 12 to heat up and activate a resetting thermal micro switch (shown in Figure 11) which will shut down the alternator until the temperature is reduced to a point when the micro switch will reset. Then allowing the normal start up feature of the welder for both, rod or TIG welding via the handle switch or main panel switch. The normally closed contacts of RLY3 will be described further on.

[0267] A spring biased normally open switch activated by push button for normal arc welding and TIG welding, is the preferred rod change or main start switch 207 and is preferably made as part of the handle assembly. This normally-open switch controls the supply line to the rotor field ready for welding.

[0268] The switch 207 is recessed or is otherwise deliberately positioned slightly below the surface of the handle so that accidental start of the welding arc is minimised when the handle is either dropped or laid down on a rough surface or possibly trod on.

[0269] Immediately after the main welding arc is established the current detection transformer 2211 circuit of Figure 22, which is in series with one phase of the main winding, for example a 3 phase or 6 phase winding (of figures 23, 24 or 25), by transformer action develops a secondary voltage which is processed by the electronic circuit associated with this part of the control system, and operates the shut down relay.

[0270] Once the operator stops welding the relays RL Y2 and RL Y3 resets the control circuitry for a restart and the capacitor(s) are removed from the welding current supply line and high voltage circuitry of Figure 9 is made ready for the restarting the welding arc.

[0271] This method of operation by the relays in Figure 22 are to prevent the high voltage from destroying the filter capacitor(s) 231 and accidental starting of the circuit of Figure. 9 during welding.

[0272] The secondary winding of 2211 consists of multiple turns of a finer wire and the output is controlled by a parallel power resistor and trim pot. The power resistor prevents high voltages developing in the winding during welding operation in case the trim pot goes open circuited and the current detection transformer secondary winding burns out also with possible damage to the associated electronics. The output from the trim pot is rectified by a diode and filtered by a small capacitor and via resistors taken to the base connection of the transistor which operates the control relay RL Y2.

[0273] As mentioned above to overcome this low output voltage, voltage doubler 8100 is provided and by a switch 815 on the main panel one of two ranges namely high and low can be selected. When the low range is selected the voltage doubler is made use of and when the High range is required the system returns to normal supply voltage.

[0274] To describe the operation of the doubler 8100 in detail, reference is made to the circuit of Figure 9. The doubler 8100 is designed around a bridge rectifier BRl and two capacitors Clvd and C2vd and a switch which selects the appropriate sections of the control winding, being one phase or the neutral 80 of the control winding.

[0275] The capacitors Clvd and C2vd are connected across the positive and negative terminals of the bridge rectifier BRl. The negative is "floating" to prevent short circuiting of the common neutral line 80 of the alternator 100. This negative line is taken to the main switch 815 and then from the switch to AC2 input of W04 BRl or switched to the junction of Cl and C2 capacitors. One phase of the three phase control winding is a direct connection to ACl of the bridge rectifier BRl .

[0276] The selection switch 815 (on the main panel) has its common terminal going to the neutral 80 point of the control winding. Of the other two terminals of the selector switch 815 one goes to AC2 on the bridge rectifier BRl and the other terminal goes to the series junction of the two capacitors Clvd and C2vd.

[0277] When the current selector switch on the control panel is in the high current position the AC power from the control winding is rectified by diodes ID and 2D and filtered by the combined series connected capacitors Clvd and C2vd.

[0278] The direct current is applied to the voltage regulator REGl via voltage stabilizer

8600.

[0279] When the low current is selected by the selector switch 815 on the control panel,

Phase 1 PHl ( assuming positive cycle ) goes through Diode 1 charging capacitor Clvd and the return path out through the switch 815 to the neutral 80.

[0280] On the negative side of the alternating current cycle the charge path is through capacitor C2vd through diode 4D and to phase CPHl . Now the combined voltages of Cl vd and C2vd are applied to the voltage regulator REG 1 via the voltage stabilizer 8600, thus restoring the diminished voltage which results from low excitation. The normal direct current voltage is available no matter the setting switch 815.

[0281] The relay RLY3 of circuit 911 (see Figure 11 , 22) is used to open circuit the start up circuit via its normally closed contacts 8339, which open once the welding arc is established and close when the welding arc is terminated or broken. This is to obtain current control when set in the low amperage mode via the switch 815 on the control panel. This gives controllable welding from low to medium current ranges.

[0282] An improved alternator start up circuit is shown in Figure 11. The circuit of

Figure 11 differs from the circuit of Figure 5 and 12 by the following.

[0283] From the main winding of the alternator the output voltage, rectified by Dl via limiting resistor PRl and thermal micro (klixon) resetting switch to the normally closed contacts of Relay RL Y3 and then to the common of no volt relay 60. The relay coil section is connected to a direct current source derived from two of the three available phases of the control winding. The circuit proceeds from the normally closed contacts of the no volt relay 60 to the high/low weld current resistor(s) change switch 815, which is connected to the rod change or main start switch 207 and then to the salient pole field coil 203 and then to the star point 83 of the control winding via neutral line 80 completing the alternator start up circuit.

[0284] The alternator start up circuit of Figure 11 is shut down whilst the rod change or main start switch 207 is open circuited. When the rely 60 coil is energized the no volt rely 60 relay RLYl disconnect the start circuit of Figure 11 during welding operation. This is backed up by RL Y3 normally closed contacts being open circuited as well.

[0285] When rod change or main start switch 207 is closed the rotor field controller 913 sets the range of current by adjusting the variable resistor or potentiometer 205, which controls current to the rotor field coil 203. The output of the control winding connects to diodes D2, D3, D4, then the voltage regulator which controls the salient pole field coil through the fuse 201, current resistors 917 (if switched in by high/low switch 815) and rod change or main start switch 207 (rod change or weld finish).

[0286] The operation of the alternator start up circuit of Figure 11 is as follows. When the prime mover drive input to the alternator begins rotation, the rotor 2 (see Figure. 1) spins and the residual magnetic field gradually increases to a point where the voltage of sufficient potential causes the no volt relay 60 to open its normally closed contacts. Once the contacts open the start circuit is taken offline and the controller 200 takes over until the voltage regulator 210 has sufficient voltage and flux in the rotor to provide welding voltage and current which is controlled by the variable resistor or potentiometer 205.

[0287] The energy in the rotor field coil 203 is now controlled by the setting of the variable resistor or potentiometer 205 on the front panel or the remote connection. The LEDs 206 and 204 indicate that there is appropriate supply available from the alternator 100. When the rod change or main start switch 207 is open circuit the rotor field 203 loses power while a new rod is fitted; this will prevent accidental electric shock to the operator. At the same time shutting down the high voltage supply if TIG is selected on switch 211 on the front panel.

[0288] When the rod or main start switch 207 closes the rotor field start circuit beings again and the operator can continue welding. This is the case for either ARC or TIG welding. The start up circuit 911 rapidly brings the alternator 100 on line. The reason that the above works is because direct current in the rotor field takes time to fully collapse and the no volt relay 60(RLYl) being speedy in operation gives the rotor field controller 200 adequate time to take over control of the current in the salient pole field coil 203.

[0289] The resettable thermal microswitch (klixon) is fitted to the start up circuit 911 to prevent the power resistor PRl from burning out in case a fault were to cause inoperability of no volt relay 60 (RLYl) which would cause the start up circuit 911 to be constantly connected, resulting in very large currents, and thus heat, in this section of the circuit.

[0290] Figure 13 illustrates an optional battery charger in the form of a unit designed to be used with the system described above to allow the charging of 12v or 24v batteries or possibly used to supply power for lighting.

[0291] Power for battery charging is derived from the same main windings in the alternator that are otherwise used for welding.

[0292] For battery charging the selector switch 211 (in Figure 11 , 29 and 34) on the main control panel is turned to a battery charging position, thus turning off all the welding and (TIG if fitted) circuits. Switch 2823 (in Figure 11 , 28, 29 and 34) turns on the battery charger plus select 12v and 24v and also connects the battery charger control circuit to the main controller 200 for control of the rotor 203 via plug 8. Switch 2823 also turns on the alternator via plug 20.

[0293] Plug 1118 goes to the main control board via connections 1131 which controls the field flux of the rotor when switch 1111 (Figure 13) or 2823 (Figure 28) is in either the 12 v or 24v position. With switch 1111 or 2823 is in the position for battery charging, a charging start relay 1113 (Figure 13) or 2831 (Figure 28) is switched and during this time the regulator 210 on the main board is set to a preset output of the alternator. When in the off position the alternator output is set to minimum.

[0294] By connection to two of the main winding phases or a main winding phase and the neutral to the bridge rectifier 1115 (Figure 13, 28) and the choke 1117 (Figure 13), and relay 1113 (Figure 13) and relay 2831 (Figure 28) normal open contacts, will make voltage available for charging a battery when connect to terminals 1121 (Figure 13 and 28).

[0295] The battery to be charged is connected to the terminals 1121 1120 and the led lights 1123 and 1125 indicate correct connection, with Green LED 1125 for correct connection and Red LED 1123 for reverse connection. The battery must be connected correctly. If fuse 1127 blows upon selecting the battery voltage via switch 1111 or 2823 then the operator must recheck connection, replace the fuse 1127, and check that the correct battery voltage is selected.

[0296] The switch 1111 is rotated to the battery voltage being charged, at the same time the power is turned on via the bottom of switch 1111 which connects the "on/off relay 1113 to the supply 1131 from the main board.

[0297] The trim pot 1133, for 12V charging and trim pot 1135 for 24V charging are normally factory set for a preferred alternator speed and should need no further adjustment.

[0298] The output from the main winding of the alternator will now be at a selected potential necessary to charge an appropriate battery via the bridge rectifier 1115. The fuse 1127 will blow in case of a short circuit or too much current by the battery if a cell or cells are faulty.

[0299] When charging is finished the switch 1111 or 2823 is returned to an off position, being switch position 2 of Figure 13 and 28 to disconnect the power to the battery.

[0300] The circuit of Figure 13 and 28 is designed to inhibit simultaneous welding and battery charging because the battery could be damaged by the power fluctuations if welding were to occur during charging.

[0301] Figs 17 to 19 show basic layouts of handle designs being controls for Arc and

TIG welding. It is preferred for safety reasons that on all handles such as those of figs 17 to 19 that the rod change or main start switch 207 is located below the outer surface of the handle i.e. recessed, to avoid accidental starting of the welding power if dropped or trodden on, as this rod change or main start switch 207 controls all circuit power functions.

[0302] Figures 20 and 21 show details of a belt tensioner designed to eliminate belt / pulley slippage under varying loads conditions. The drive belt preferably should not slip, and stretch must be re-tensioned which will happen automatically by the arrangement of figures 20 and 21. In the arrangement an easy method for belt changing by the operator is readily available.

[0303] The tensioner system of figs 20 and 21 takes into account the high speed of the pulley arrangement and reduces wear on the drive and driven pulleys.

[0304] Figure 20 illustrates an idler pulley rectangular mounting bracket 2013 which is pivoted and carries at one end a countersunk bolt for securing the idler pulley 2011 in conjunction with a central high speed bearing.

[0305] Located to the other side of the pivot or fulcrum, is a securing point to mount one end of tension spring 2010, which is secured at its other end on the base of the main bracket 2009. The tension spring 2010 maintains clockwise bias on the right side of bracket 2013 causing pulley 2011 via the pivot to maintain tension on drive belt 2008 thus preventing belt slippage either on the drive or driven alternator pulley.

[0306] Figure 21 illustrates how to release the belt 2008. With the belt release lever

2017 in position, it is an easy operation to remove the belt. As fulcrum or pivot pin 2018 on the lever 2017 is inserted into hole 2019 on bracket 2013 so that pressure applied to the handle rotates the bracket 2013 anti clockwise.

[0307] By this means the idler pulley 2011 is moved anticlockwise thus allowing easy removal or fitting of a new drive belt. If desired, a safety cover over the belt can have a micro switch that disengages the engine power thus the engine cannot be used without the covers being secured.

[0308] Illustrated in Figure 12 is a PCB layout of the control panel similar to that of

Figure 6, and like parts have been like numbered.

[0309] The PCB layout of Figure 12 embodies the schematic circuit of Figure 11.

[0310] Illustrated in Figure 26 is an arrangement similar to the previously described mobile welders, except that a second high frequency alternator 101 is arranged in parallel with an alternator 100. All control circuitry, start up circuitries etc are the same as for previously described embodiments.

[0311] What is different with the embodiment of Figure 26 is that alternator 101 has its main winding, MPHl, MPH2, MPH3 going to a bridge rectifier 2613 whose current output adds to the current output of the rectifier 230, and proceeds to the welding handle.

[0312] The rotor field control connectors 516 and 517 of alternator 101 are connected in parallel to the rotor control connection 516 and 517 of alternator 100.

[0313] The bridge rectifier 2613 has its Klixon or micro therm switch 2615 which is also in series with Klixon 2617 on the heat sink 415 of the rectifier 230, 232, 233(Figure 26) associated with alternator 100 and 101.

[0314] As will be readily understood additional alternators can be added in parallel as is described above. Obviously appropriate controls will be required.

[0315] It will be noted from Figure 26 that the alternators 100 and 101 have klixons

2619 in their respective stators and Klixons 2621 in their main windings. Klixon 2621 controls a visual indicator such as an LED 3413 (see Figure 34) that the windings are approaching over temperature conditions. Once these conditions cause the stator temperature to reach 14O ⁰ C the Klixons 2619 will open circuit to open the contacts of relay RLY5/1 of Figure 35. The circuit is design to reduce the magnetic flux level in the rotor field by adjusting regulator 210 to drop the output voltage in the alternator to a level where the temperature can decrease, yet maintain enough voltage to operate the control panel LEDS, specifically the red over temperature LED.

[0316] Once over temperature in the stator occurs, as indicated by the red LED, the operator will experience a loss or diminishing of welding arc. Once the temperature decreases the red LED will go off and the welding arc and main winding output will be restored

[0317] Illustrated in figures 27 and 28 are schematics showing connectors from the alternator to a battery charging circuit. The circuit, and the battery charger circuit respectively. The battery charging system of figs 27 and 28 is an improved system when compared to the charger of Figure 13 and like parts have been like numbered.

[0318] Voltage is applied to the battery charging circuit of Figure 28 by connection to two of three main winding phases and the common connection called the neutral 80. Connection to phase MPH2 is controlled by the relay RLY T. Phase MPHl is a direct connection to a bridge rectifier 1115. The second relay RLY S, selects the neutral 80 common line to the bridge rectifier 1115.

[0319] The output from the positive of the rectifier 1115 goes to the current regulating transistors (TIP36) 2814 then through a diode 2815, fuse 1127, and then to the positive terminal 1121 for the positive battery connection. The negative line 1120 is the common line for the battery circuit, which connects to a floating common from the negative terminal of bridge rectifier 1115. Controlling the transistors 2832 and 2814 is a 12 volt regulator 2817 which has its output raised by the use of an LED 2818, diodes 2819, 2820 in each of the 12v and 24v settings. There are decoupling capacitors or filter capacitors 2821 and 2822 in the input and output of the regulator for noise and spike protection.

[0320] 12v or 24v volt charging is selected by a four pole 3 position selector switch

2823 which turns on the field of the salient pole rotor via plug 20 on the main regulator controller board.

[0321] The SWlD portion of switch 2823 selects one of the appropriate relays for charging the 12v or 24v volt battery.

[0322] The SWl C portion has trim pots for setting up the voltage levels of the salient pole rotor winding via the adjustable input of the regulator 210 on the main controller board for supplying power for charging to 12v or 24v volt battery.

[0323] Power for the two relays is supplied from the main controller board plug 2 (P2) which is fed to the 2x270 and 220 ohm resistors in parallel to the common of the SWlD portion of the selector switch 2823 which is the start or neutral 80 and is common for the relay circuit only. Before switching from welding to charging (12 or 24 volt positions) correct connection of the battery to the charger is indicated by a green LED light 1125 and charging can commence. Should the battery be connected to the charger in reverse, then a red led light 1123 will illuminate. If this happens the operator should swap the batter connections to obtain a green light from green LED 1125.

[0324] Figure 27 illustrates the battery charger connections of Figure 28 when used in a

6 phase system and shows connection of rectifiers 1115 to outputs MPHl and MPH2 from block rectifier 233 (constructed as in Figure 25).

[0325] In Figure 29 which illustrates the connections between the controller of Figure

30 and the TIG board of Figure 31. Block 2833 are components of the battery charger which are the rest of the circuit of Figure 28, not present in Figure 27, and connects to the connection diagram of Figure 27 by plug P40.

[0326] Illustrated in figures 29 and 30 are the PCBs of the main control panel. Figure 31 is the TIG start up circuit of Figure 9, respectively. Also Figure 31 includes the circuitry of the current detection transformer control 2211 described above see Figure 22.

[0327] The PCB of Figure 31 is a modular unit and plugs into the PCB of Figure 30 by means of interconnecting plug Pl 1 on PCB of Figure 30 to plug Pl IA on PCB of Figure 31. The only other connection required is from the one phase of the control winding and this is seen bridging terminal PHA on PCB of Figure 30 to terminal COMphAC on PCB of Figure 31.

[0328] The capacitor 231 (see Figure 23 and 31) is connected into plug PlO on PCB of

Figure 31 or PlO on the PCB of Figure 30.

[0329] If PCB of Figure 31 is not to be present in a mobile welder, then connections from PIl and PHA are not required but capacitor 231 is connected into plug PlO on PCB of Figure 30. There is a jumper connection for Pl 1 of Figure 30 PCB to close the start up circuit when the switch 207 on the handle or main panel is activated.

[0330] In the PCB of Figure 31 there is present an oscillator to provide high voltage for the high voltage multipliers 8200 of Figure 9 to provide a starting voltage for the main arc in a TIG welding application. It has been noticed that whilst effective the distance of the weld rod away from the work piece at which TIG welding will start, can be improved, that is, it can be started from further away from that work piece. To effect such an improvement the TIG starting circuit of Figure 43 can be utilised and is described as follows:

[0331] Illustrated in Figure 43, in the top portion thereof is a bistable oscillator circuit

4300, which derives power from the Variable Voltage Regulator WR and is a nominal 11.6 - 12 volts DC approximately 0.97 - 1.2 amps. The circuit 4300 is a basic bistable oscillator operating at 1650 Hz measured across the transformer T2 secondary winding S, the frequency being controlled by the size or magnitude of the resistor/capacitor combination (47OpF, 20kOhm and 68pF) and has a centre taped high frequency transformer T2, connected into the collectors of each transistor TIP122/ONHS, these transistors being of the Darlington type. The oscillator 4300 is self-starting due to circuit unbalance caused by component tolerances. The operation is well understood by those in the electronic field.

[0332] The secondary of the transformer T2, has a capacitor Cl 1 in series with one leg of the transformer T2. As the transformer T2 is producing an alternating current the capacitor's reactance is used as a current controller, with the amount of current depending upon the size of the capacitor, thus for more current then the capacitor size can be increased that is as capacitive reactance decreases the current increases.

[0333] The AC voltage output from the transformer T2 of the Oscillator circuit 4300 via the capacitor Cl 1, is fed to a bridge rectifier Dl for rectification. The output is taken to a pulser circuit 4400. Attention is directed to the presence in Figure 43 of a 150ω 5 watt resistor R4 in the negative rail from the bridge rectifier Dl . The DC supply is now taken from the positive output of the bridge rectifier Dl and the end of the 150ω 5 watt resistor R4. Across the supply is connected a resistor Rl, capacitor Cl, a Zener diode D2 connected with R2, R3 to form a Zener controlled voltage divider. Capacitor C2 and the gate junction join to the junction of R2 and R3. The cathode of the silicon controlled rectifier is taken to the negative rail (end of the 150ω 5 watt resistor).

[0334] The anode of the SCR CR3 JM is connected to the low voltage (P) side of the HV transformer Tl and the other side of Tl to the positive rail. Across the SCR CR3JM is a diode D6 to protect the SCR CR3JM from transients voltages from Tl or from "ringing". The high voltage secondary side S is connected to the cathode of a very high voltage diode D4, the anode being joined to capacitors C3 and C4 which are in parallel and which return to the negative rail of the bridge rectifier Dl .

[0335] From the junction of D4 anode and the capacitors C3, C4 is a spark gap Xl . The other end of spark gap Xl is joined to gap X2 then onto a ferrite potential transformer TXl as illustrated in Figure 47 which then joins to the negative rail, via the 150ω resistor R4.

[0336] This transformer TXl will be discussed below.

[0337] The AC voltage from the Oscillator 4300 goes to the AC input of rectifier Dl .

The DC output from the 150ω resistor R4 to the negative rail and as the positive rail has Rl and Cl along with D2 and the voltage divider across the supply Cl is charged by the output of the bridge rectifier Dl, Rl assists to stabilize the supply and serves as a "bleed" resistor for capacitor Cl . When Zener diode D2 conducts the voltage divider supplies voltage to capacitor C2 which initially is a short circuit until charged, at which time the gate sensing a "turn on": voltage being the voltage at the junction of resistors R2 and R3 thus turning on the SCR CR3JM.

[0338] When the SCR CR3 JM conducts, this action places the primary of high voltage step up transformer Tl across the potential of the DC supply less a 0.6 volt drop across the SCR CR3JM. This discharges the capacitor Cl that now puts a short circuit across the SCR CR3JM

thus turning it off and allowing the capacitor Cl to recharge and so this is repeated over again thus creating a pulse from the pulse circuit 4400.

[0339] Returning to the high voltage transformer Tl the pulse voltage built up in the primary P is mirrored by the transformer action of Tl . Due of the high number of turns on the secondary S of transformer Tl a high voltage is developed in the winding S which is rectified by diode D4 which charges the capacitors C3 and C4 up until spark gaps Xl and X2 close the circuit thereby discharging the high voltage across transformer primary TXl .

[0340] As the SCR CR3JM and transformer Tl apply the DC supply the AC input makes use of the series capacitor Cl 1 and the 150ω 5 watt resistor R4 to reduce loading on the oscillator circuit 4300. This oscillator circuit 4300 operates for about 5 - 10 seconds of actual use to start the main arc for TIG Welding, when a welding is started.

[0341] The transformer Tl, diode D4, capacitors C3 and C4 and the Spark Gaps Xl and X2 are mounted on a separate printed circuit board so that the entire printed circuit board can be enveloped in silicone so as to prevent high voltage flash over or arcing which may otherwise occur due to dust and or moisture accumulating on or around the printed circuit board. To further ensure this, only the connection terminals are left bare for transformer TXl connection.

[0342] The high voltage transformer TXl is constructed in the manner described in

Figure 47 in that it uses a single cylinder ferrite core having itslength which is insulated, and a glass sleeve fitted to the outer diameter with a reasonably tight slide fit. An insulated copper conductor of appropriate size is wound over this glass sleeve and consists of some 25 - 28 turns of 4mm PEI insulated wire with the leads terminated to high current connection lugs, in a single layer winding.

[0343] Another layer of insulation is applied to the first heavy conductor winding upon which is a layer of insulated flexible cable preferably glass covered or of an insulation rated for 10kv - 5/10 amps or better.

[0344] This layer of flexible cable, called the Primary P, consists of some 7.5 turns, securely fixed by a layer of glass tape or ribbon into position and varnished to prevent movement. The lead ends being terminated with small slide on spade lugs for attachment to the high voltage printed circuit board, with the output polarity being of no importance.

[0345] The high voltage pulsed output of the pulse circuit 4400 is transformed by transformer TXl so that there is a high voltage present on the secondary S of the transformer TXl. As each firing of the pulse circuit 4400 is performed, a resultant high voltage is present at the secondary terminals which are connected to the TIG handle and the three phase power bridge

rectifier Dl direct current output. This completes the circuit ready for an arc start for TIG welding.

[0346] With reference to Figure 44, because there is a high voltage present at the rectifier Dl terminals, protection during the starting of an arc is preferable. This protection is provided in the form of a parallel bank of resistors RB, and high voltage capacitor HVC in series therewith, which is fitted to the positive and negative terminals of the rectifier Dl .

[0347] The capacitor HVC does not conduct but rather takes a charge when used as an ordinary stick weld, i.e., non arc start. When in TIG welding mode the high voltage capacitor HVC charges and discharges, the resistor bank RB limiting current each time the pulse circuit 4400 fires and delivers high voltage to the TIG handle The resistor bank RB and capacitor HVC provides protection for the power bridge rectifiers 230 (see Figure 23) or power bridge rectifiers 232 and 233 (of figures 24 and 25). When the welder is set up for battery charging or in the case of stick welding, the high voltage arc start (used only for TIG welding) is OFF, and the protection circuitry has no effect on the DC output from the power bridge rectifiers 230 (see Figure 23) or power bridge rectifiers 232 and 233 (of figures 24 and 25).

[0348] Illustrated in figures 32 and 33 are the remote control connection and potentiometers for use with remote controls on welding handles.

[0349] In Figure 39 is a schematic of the welding lead terminals provided on the main control panel, which shows the use of interlock switching which in turn plugs into plug Pl 5 of the TIG PCB of Figure 31. The purpose of these is to isolate the TIG board unless the interlock switch is closed, indicating a TIG welder connection has been made to the weld lead connection of Figure 39. If stick welding is to be done then the welding leads from a stick welding handle will not close the interlock switches thus keeping the TIG board of Figure 31 isolated and inactive.

[0350] Illustrated in Figure 42 is a voltage doubler having automatic selection with wiring for appropriate switching between High and Low current ranges and a Low range automatic selection relay control to maintain the high voltage for starting the welding arc to ionize the gas for the main welding arc for thin gauge material, like stainless steel and copper sheet and the like. This will be useful should the operator require a very low welding current for very thin sheet welding. This would require a further reduction of the flux field in the rotor, and the arc starting voltage would be intermittent or extremely low and may not ionize the gas to fire up the main welding arc, with possible TIG arc tip or rod sticking to the job to be welded.

[0351] With reference to Figure 42, when the selector switch 815 (SWlA /B) ( on main panel ) is positioned in the "H" or high position, the Neutral 80, is connected to the AC3 input to the bridge rectifier. It is seen that the other AC4 terminal is a permanent connection to CPHl control winding from the alternator no matter the TIG Current.

[0352] The output supply voltage from the positive and negative terminals of rectifier

BR4 are joined to the two series connected capacitors C28-C29, and connected to the voltage stabiliser 8600 shown in Figure 9.

[0353] The upper end of the low current range is selected by a selector switch 815 on the main control panel, at the same time the relay RL Y8 is energised and the Neutral 80 is connected to the centre connection of the two capacitors C28 and C29, thus producing a doubling of the input voltage to the voltage stabiliser of Figure 9.

[0354] When the lower end on the low current range is selected (for TIG welding of thin sheet or tubing) by altering the variable resistor or potentiometer 205 on the main panel of (Figure 29 and 34) reduces the rotor field voltage. The relay RLY8, open circuits due to the series Zener diode ZDl which stops conducting and shuts down the supply to the relay RLY8. This will connect the control winding CPH2 two the junction of the two capacitors which will increase the TIG high voltage for ARC starting of the main welding arc.

[0355] Illustrated in Figure 45 is an alternative start up circuit to allow for higher currents to be taken by the startup relay coil which may otherwise result in damage to the coil, which in turn may result in the RLYl contacts staying in the start-up position thus leaving the alternator with vitally no field control of the alternator stator winding.

[0356] In the circuit of Figure 45, the start up relay coil is operated within a preferred coil current for this type of relay. The diode D3 connected across the relay RLYl helps to prevent relay chatter and field oscillation when in TIG mode of operation. Further a light emitting diode LEDl has been included to indicate the presence of power that activates the relay RLYl and is a helpful indicator for servicing.

[0357] Illustrated in Figure 45, two of the exciter phases are used in controlling the

"start up " relay RLYl for the starting of the field flux of the alternator. These are connected to the AC input of a single phase bridge rectifier Dl, while the output from the rectifier Dl has a filter capacitor C3 across the positive and negative terminals. A pre-regulator transistor Ql is connected into the positive line and the junction of the resistor Rl and Zener diode D2 voltage divider is taken to the transistor Ql base connection, the emitter of Ql being connected to two filter capacitors Cl, C2 and to the input of a fixed voltage regulator Ul, supplying power to the

start up relay coil RLYl. A light emitting diode LEDl, and current control resistor R2 are included to indicate the presence of voltage should a fault develop with the welder circuits, that is, light emitting diode LEDl can aid diagnosis of a fault problem.

[0358] The Zener diode D2 sets the voltage applied to the input to the regulator Ul , the voltage being the Zener voltage less 0.6 volts. The resistor Rl is selected to ensure adequate current through the Zener diode D2 ensuring a voltage reference for the pre regulator transistor or pass transistor Ql . This is determined by the maximum power dissipation of the Zener Diode D2.

[0359] The regulator Ul requires an input voltage to be at least 2.5 to 3.0 volts above the rated output voltage of the regulator Ul. If this voltage is set by the Zener diode D2, then the pre regulator transistor Q2 will perform the dissipation of the remainder of the power.

[0360] Due to the low power requirements it has been found that heat sinks are not required for the pre regulator transistor Ql or the regulator Ul as the relay RLYl operates with a coil current of 35 - 40 mA.

[0361] If it is desired to provide TIG welding at low current, then the high voltage circuit 4500 of Figure 46 can be utilised.

[0362] Referring to Figure 46, the AC voltage from the alternator exciter winding is applied to the voltage sensitive relay VSR, via a plug 24A/B which also routs the necessary DC supply for the relay coil, and after range selection by the relay VSR contacts CNTl, is taken to a bridge rectifier BR, and filtering capacitor C2 then out to a variable voltage regulator WR, which is set by the trim pot TP having a maximum resistance of 5Kω for 11.6 to 12 volts DC output.

[0363] The variable voltage regulator WR 46 is comprised of an integrated circuit

LM338 which is mounted on a heat sink as it will be supplying 1.2 amps to the oscillator circuit 4300. The trimpot TP can be a sealed type and once set then locked into position by an adhesive such as a fingernail polish, varnish or the like. The bridge rectifier BR is a 1.8 amp full wave in line rectifier. The voltage applied to the voltage sensitive relay VSR is derived from the regulator board, i.e., at the junction (positive output) of the three main rectifier diodes and neutral star point. With the Zener Diode Zl and two resistors Rl and R2 in combination, a nominal 17 volts DC is used to cause the relay VSR to close, which is controlled by transistor TRX. Thus the action of the relay VSR is to produce lower than 17 volts so that the relay VSR stays non- energized and the two AC phases are connected to the bridge rectifier BR, thus giving a phase to phase supply to bridge rectifier BR. When 17 volts is exceeded the relay VSR changes the AC supply connection to phase and neutral which is V3 volts AC less voltage to the bridge rectifier BR, thus a lower output to the regulator WR.

[0364] As illustrated in Figure 46 the relay VSR contacts CNT2 are wired across resistor RX and are in series with the coil of rely VSR to the transistor TRX and neutral, with the other side of the relay VSR being connected to the positive rail from the diodes D2, D3, D4 via P24A/B. Also a capacitor Cl is present across the coil of the relay VSR which stops chattering of the relay contacts.

[0365] The Zener diode Zl , has a resistor Rl in series with the base of the transistor

TRX to limit the base current. The resistor R2 makes certain the transistor TRX turns off in the absence of a break over voltage in Zener diode Zl to drive the base of transistor TRX. Once this voltage is detected by the base of transistor TRX and exceeds 0.6 volts the transistor TRX conducts and connects the circuit of the coil of relay VSR to the neutral rail and opening the contacts CNT2 connecting power saver resistor RX so as to limit the current in the coil of the relay VSR. When this happens, the bridge rectifier BR is changed from a two-phase connection to a single-phase connection as described above.

[0366] Whilst the above description of 3 and 6 phase windings are currently the most preferred, it will be understood that with suitable sizing and slotting of the laminations and with winding design, that a twelve phase alternator, allowing for room and size permitting, along with diameter and peripheral load conditions, can be constructed which could improve the output of the alternator with appropriate rectifiers for direct current welding.

[0367] The mobile welder of the latter embodiment described above can TIG weld, and has also proved capable for light and heavy gauge steel and stainless steels, and aluminium welding.

[0368] It will be understood by the reader that the invention disclosed and defined in this document extends to all alternative combinations of two or more of the individual features mentioned or evident from the text. All of these different combinations constitute various alternative aspects of the invention.

[0369] The foregoing describes embodiments of the present invention and modifications. Obvious to those skilled in the art variations can be made and not limited to one design, but are all covered in the scope of the present invention.