BACKGROUND OF THE INVENTION The present invention is directed to a highly efficient, relatively compact, relatively

inexpensive motor, that can operate at synchronous speeds depending upon the frequency of

5 the input. The present motor is also relatively easily reversible, generates little or no heat in

the rotor, has a simple rotor construction, does not require any shading coils and can have its

torque programmed both during running and starting.

DISCUSSION OF THE PRIOR ART

Applicant is the inventor of several previous motor constructions using permanent

o magnets as a portion thereof including those disclosed in the patents and patent applications

listed below:

1 ) Flynn et al U.S. Patent No. 5,304,881 , issued April 19, 1994 entitled MEANS

FOR PRODUCING ROTARY MOTION.

2) Flynn et al-Divisional U.S. Patent Application Serial No. 08/226,950, filed

5 April 13, 1994, entitled MEANS FOR PRODUCING ROTARY MOTION.

3) Flynn U.S. Patent No. 5.254,925. issued October 19, 1993, entitled

PERMANENT MAGNET CONTROL MEANS.

4) Flynn-Divisional U.S. Patent Application Serial No. 08/104,783, filed August

1 1, 1993, entitled PERMANENT MAGNET CONTROL MEANS.

5) Flynn U.S. Patent Application Serial No. 07/902,952, filed June 23, 1992,

entitled MAGNETIC MOTOR CONSTRUCTION.

Applicant's prior art constructions for the most part employ direct current energy and

control means and for this and other reasons the present construction represents a departure

from Applicant's prior art constructions.

SUMMARY OF THE INVENTION

The present invention is directed to a relatively inexpensive, highly efficient motor

which can be controlled to rotate in either opposite direction of rotation. The motor includes

at least one motor field coil in series with switching means which are under control of a

control electronic circuit which in turn is controlled by a sensor device. Several different

5 embodiments of the subject motor are disclosed, and all of them have the same basic control

features and can be operated from an alternating current source, the frequency of the source

being used to control and determine the speed of rotation of the subject device.

OBJECTS OF THE INVENTION A principal object of the present invention is to provide a motor operable on single

o phase alternating current power that is highly efficient and can be made reversible, does not

produce heat in the rotor and is programmable during running as well as during starting.

Another object is to provide a single phase alternating current motor that is self

starting and operates at a synchronous speed based on the frequency of the input energy

source.

5 Another object is to teach the construction of a single phase alternating current motor

that does not require any shading coils.

Another object is to teach the construction of a motor that uses readily available

inexpensive parts and that can replace many existing motors in the market place.

Another object is to provide a motor that can operate at a greater number of

0 synchronous speeds.

Another object is to teach the construction and operation of a motor that operates

similar to a dc motor during start up and at a synchronous speed when running normally.

Another object is to teach the construction and operation of a motor that operates

efficiently under load and behaves as a dc motor when the motor speed is pulled down.

Another object is to provide a circuit for an ac motor which is relatively simple

structurally and which uses one or more coils including bifilar coils which operate

independently in association with respective rectifier devices such as silicon controlled

rectifier devices.

Another object is to pass current in a desired direction through one or more coils

wound on a stator under control of respective controlled rectifier devices.

These and other objects and advantages of the present invention will become apparent

after considering the following detailed specification covering preferred embodiments thereof

in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side elevational view of a motor constructed according to the teachings of

the present invention;

Fig. 2 is a side elevational view of the motor shown in Fig. 1;

Fig. 3 is a circuit diagram for the motor shown in Figs. 1 and 2;

Fig. 4 shows one shape for the permanent magnet portion of the rotor;

Fig. 5 is a circuit diagram showing another form of control circuit for the subject

synchronous motor;

Fig. 6 shows a modified form of the rotor for use with the motor circuit of Fig. 5;

Fig. 7 is a simplified block diagram showing the main operating components of the

circuitry for the subject device;

Fig. 8 is a graph showing an alternating current input voltage in association with

respective half cycle graphs of the alternating current input voltage on alternate half cycles;

Fig. 9 is a schematic diagram of another preferred embodiment of the subject device;

Fig. 10 is circuit diagram showing yet another embodiment of the circuit for the

subject device;

Fig. 1 1 shows an alternative embodiment of the circuit for the silicon controlled

rectifiers shown in Fig. 9 using MOSFETS instead of SCRs;

Fig. 12 shows an alternate embodiment of the circuit for the silicon controlled rectifier

shown in Fig. 10 also using MOSFETS instead of SCRs; and

5 Figs. 13 and 14 show an alternate connection for the circuits of Figs. 9 and 10 using a

light emitting diode to control the turning on and turning off of the circuit.

BRIEF DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

Referring to the drawings more particularly by reference numbers, number 10 in Figs.

1 and 2 refers to a motor constructed according to the present invention. The motor 10 has a

10 circuit board 12 mounted on one side with diodes, resistors, capacitors and SCRs mounted on

it. The motor 10 has a rotor 14 with peripheral permanent magnet portions 15A and 15B

constructed as will be described, a timing magnet 16, bearings 18, a motor shaft 20, a Hall

Effect or like switch device 22 mounted on the circuit board 12, a laminated iron core stator

member 24 and coils 26 such as bifilar coils mounted on the cross portion 28 of the

15 laminated stator core 24 as shown. The timing magnet 16 extends to closely adjacent to the

Hall Effect switch device 22. The circuit for the motor 10 shown in Figs. 1 and 2 is set forth

in Fig. 3 and defines a self starting controllable synchronous motor which operates

synchronously at the frequency of the alternating current input or at some submultiple

thereof. The subject motor operates by opening and closing the switch or Hall Effect device

20 22 in response to the position of the timing device 16.

Fig. 3 shows the circuit for the subject motor including a standard bridge rectifier

circuit 30 formed by four diodes Dl, D2, D3 and D4 connected as shown. The bridge circuit

30 can be composed of discrete components as shown or it can be a single four pin integrated

bridge circuit. The type of bridge circuit selected for the motor will depend upon factors such

25 as cost. The circuit also includes resistors Rl and R2 which may be of conventional

construction such as being ^l λ watt resistors. The resistors Rl and R2 supply gate biasing

voltages to the gate elements of SCRs 1 and 2 connected into the circuit as shown. The

values selected for the resistors Rl and R2 will determine the firing angles of the SCRs. The

stator core of the present device is a laminated iron member with leg portions 32 and 34 and

5 connecting portion 28 on which are mounted coils 26; designated as coils LI and L2. The

stator windings may be bifilar wound in order to reduce the number of electrical components

required to switch the magnetic polarity of the stator, by half. A bifilar winding is one were

the two winding portions are laid down at the same time so that they both have the same

diameter. They also have the same magnetic characteristics. This is to be distinguished from

o two windings, one wound on top of the other where the outer coil has a larger diameter than

the inner coil. A bifilar winding has different characteristics than coils where one is located

on top of the other. The dots shown next to the windings LI and L2 in Fig. 3 indicate the

beginning ends of the respective coils LI and L2 as they are wound. Physically the coils are

next to each other on the spool or other device on which they are wound or mounted.

5 Associated with each of the windings LI and L2 is a respective diode D5 and D6 connected

in parallel therewith as shown. The diodes D5 and D6 are back diodes and are included to

cancel any electromotive force (EMF) induced from the coils LI and L2 or vice versa and

also are included to cancel the back EMF due to switching between the coils LI and L2. This

is done to assure that the SCRs will turn off in the absence of gate current. Other resistors R3

0 and R4 are connected to the cathodes of the respective SCRl and SCR2 and are provided to

return the respective SCR gates and the cathodes of the respective SCRs to non-conducting

condition as required. Other diodes D7 and D8 are included as blocking diodes and are

connected between the respective resistors Rl and R2 and the gates of the SCRl and SCR2.

The circuit also includes a zener diode ZD1 that provides two functions including

providing a regulated supply voltage for the Hall Effect switch SI and raises the potential of

voltage on the cathodes of the SCRs to a value above the negative voltage supplied by the

bridge circuit 30 by an amount equal to the voltage value established by the zener diode.

This is done to assure turn off of the SCRs when turn off is required. A capacitor C2 is also

provided and is connected as a by-pass around a portion of the Hall Effect device SI . The

capacitor C2 prevents oscillation of the Hall Effect device due to electrical noise, and the low

current load coupled with the internal capacitance which the resistor Rl is presented to the

open collector output of the Hall Effect device SI.

The bridge circuit 30 converts the alternating current input to a pulsating dc which has

the same frequency as the input ac. The pulsating dc varies between zero volts and the peak

voltage applied to the inputs at the same frequency as the ac input. The coil portions LI and

L2 are respectively connected in series with SCRl and SCR2. The two coils LI and L2 and

the respective SCRl and SCR2 are wired into parallel circuits as shown, and the parallel

circuits are in series with the zener diode ZD1. The coil LI is referred to as the start winding

and the coil L2 is referred to as the finish winding. Both are connected to the positive output

of the bridge circuit 30. In this regard, it should be noted that the output of the bridge circuit

varies from zero volts to the peak input value of the input AC voltage, and therefore is not a

steady state positive voltage. This is important to recognize.

The start winding LI is connected to the anode of SCRl and the finish winding L2 is

connected to the anode of SCR2. The cathodes of both SCRl and SCR2 are connected to the

cathode of the zener diode ZD1 and the anode of the zener diode ZD1 is connected to the

negative output side of the bridge 30. Back diodes D5 and D6 are in parallel respectively

with the coils LI and L2 and are provided to cancel any back EMF due to switching. Since

the windings LI and L2 are energized in opposite directions through the respective SCRs, if

SCRl is triggered into conduction, the coil LI will provide an opposite magnetic polarity in

the stator than when the coil L2 is triggered into conduction by SCR2.

If both SCRl and SCR2 were triggered into conduction at the same time, which can't

happen, the magnetic field in the stator would be zero. In the particular construction shown

only one of the SCRs is allowed to be conducting at any given time. If SCRl is conducting

then the stator is of the opposite magnetic polarity of what it would be when SCR2 is

5 conducting. To prevent both SCRl and SCR2 from conducting at the same time, SCR2 is

connected in such a manner that it is a slave to SCRl . The gate current to turn on SCR2 is

derived from a circuit path through LI, R2, and D8. Thus when SCRl is conducting, the

potential at the junction of LI and R2 will generally be somewhat higher than the voltage

drop across the diode D7, and if this is true then SCR2 can not be triggered into conducting

10 while SCRl is conducting. There are short periods of time however, when the output from

the bridge circuit 30 crosses zero volts and where the possibility exists that either SCRl or

SCR2 could go into the conducting condition. This is prevented from happening by making

the conduction angle slightly greater for SCR2 than for SCRl which means that SCRl will

go into a conducting condition earlier in the cycle than SCR2, and SCR2 therefore can not go

15 into a conducting condition unless SCRl is turned off by the Hall Effect device SI.

The Hall Effect device SI is located on the circuit panel 12 and is positioned adjacent

to the two pole permanent magnet timing device 16, see Figs. 1 and 2. The timing device 16

is mounted on the rotor shaft 20 and rotates with the rotor. The timing device 16 has a

peripheral permanent magnet ring portion formed by north and south pole portions 16A and

20 16B. The number of poles on the rotor determines the number of poles on the member 16.

A two pole rotor, for example, will have a two pole stator and a timing ring composed of two

portions including a north pole portion of 180° and a south pole portion also of 180°. The

Hall Effect device S 1 has an open connector output 40 which conducts when the polarity of

the magnetic timing device 16 adjacent thereto has a specific polarity. The open connector

25 output 40 of the Hall Effect device SI in combination with the resistor Rl and the diode D7

determines, by the angular position of the timer 16, whether SCRl will be in a conducting

condition or in a non conducting condition. Since SCR2 is a slave to SCRl, the state of

SCR2 will always be the opposite of the state of SCRl . Therefore, during a single rotation of

a two pole synchronous motor such as the motor 10, SCRl will be conducting for 180° and

SCR2 will be conducting for the remaining 180°. The Hall Effect device SI effectively

"channels" all of the pulses from the bridge circuit 30 to SCRl or SCR2 depending on the

angular position of the rotor 14 and the timer 16 until the rotor 14 reaches synchronous speed

and locks to the pulsating dc.

Both SCRl and SCR2 turn off every time a pulse from the bridge circuit 30 crosses

zero volts and remain off for a short interval after the zero crossing. The state of the Hall

Effect device S 1 , depending upon the angular position of the magnetic timing member 16,

determines which SCR is on and which is off. The shortest time that a SCR can conduct in a

pulsating dc circuit is the time from zero crossing to zero crossing minus the firing angle. For

a sixty cycle input applied to the input of the bridge circuit 30, this time will be about .008

seconds. If the firing angle is 10° the time prior to firing would be approximately .0005

second and the total conduction time would be .008 - .0005 or .0075 second. One of the

novelties of the present circuit is that when the circuit is used with a synchronous motor (a

motor that has an equal number of stator and rotor poles) the amount of time the gate circuit

is maintained during each cycle of pulsating dc does not exceed the time period of one cycle

of the pulsating dc. When the frequency of the Hall Effect device SI is equal to the

frequency at the input of the bridge circuit 30, the rotor will lock onto that frequency.

It is important to recognize that with the present motor during start up the motor is

similar to a dc motor except that pulsating dc power is applied rather than a steady state dc

power. When the speed of the motor in revolutions per second (RPS) is equal to the

frequency of the ac power applied to the input of the bridge circuit 30, the motor locks to the

input frequency and for all practical purposes the Hall Effect device could be removed or

switched off because the motor now acts as a synchronous motor. If during synchronous

operation a load is applied that is sufficient for the rotor to lose its lock on condition then the

Hall Effect device SI will have a frequency that is less than the input frequency and the

motor will again behave as a dc motor and rotation will depend upon the Hall Effect device to

channel the incoming pulses to the proper stator coil LI or L2 until the rotor again reaches

synchronous speed.

Referring to Fig. 5 there is shown another form of control circuit 50 which is for a

quarter wave operation at 60 cycles. The circuit 50 is connected across a single coil 52 and

the circuit includes a pair of oppositely polarized silicon controlled rectifiers (SCRs) 54 and

56 connected as shown. The gate electrodes 58 and 60 of the SCRs 54 and 56 are connected

together through resistors 62 and 64. The common connection 66 between the resistors 62

and 64 is connected through another resistor 68 to one of the common connections 70

between the SCRs 54 and 56. The common connection 70 is connected to one side of the

input voltage source 72 by lead 74. The opposite sides of the SCRs 54 and 56 at common

connection 76 are connected to one side of the coil 52, the opposite side being connected to

the other side 78 of the input power source 72. The input power source 72 can be any

alternating current input such as a 60 cycle input source from a wall plug or the like. A

normally open switch (or sensor) 80 is connected into the circuit 50 between the common

side 66 of the resistors 62 and 64 and the common connection 76 on one side of the SCRs.

When the switch 80 is closed it places the resistor 68 across the SCRs 54 and 56 and in affect

establishes an ac voltage across the coil 52. This is the condition that is established when the

rotor is not rotating or is rotating at less than synchronous speed. As the rotor rotates the

switch 80 will open and close on alternate half cycles of rotor rotation and will establish a

synchronous speed for the rotor depending upon the frequency of the input voltage between

connections 74 and 78. The circuit shown in Fig. 5 is a quarter wave circuit.

The coil 52 can be mounted on the connecting core portion 28 of the stator 24 such as

shown in Fig. 1 of the drawing. In this construction it is contemplated that the peripheral

permanent magnet portions of the rotor will be tapered from end to end around the

circumference thereof as shown in Fig. 6. The circuit 50 shown in Fig. 5 operates basically in

the same way as the circuit shown in Fig. 3 in that the rotor is self starting and works its way

up to synchronous speed where it locks on and remains rotating unless and until the speed is

drawn down under load or for some other reason and then returns to pulsating dc control to

build up the speed to synchronous speed.

It is apparent that many different circuits and circuit elements can be used in place of

circuits and circuit elements shown is Fig. 3. For example, the Hall Effect device could be

replaced by a traic. a reed switch, optical means responsive to the position of the rotor,

transistor devices, or MOSFETS. The SCRs could also be replaced by equivalent controlled

circuit elements including by MOSFETS or the like. By properly timing the timer element 16

on the shaft 20, it is also possible to reverse the direction of rotation of the rotor.

Furthermore, since the subject motor operates as a synchronous motor except during starting

and stopping, by selecting the desired frequency for the input alternating current source it is

possible to have the subject motor operate at different synchronous speeds. The synchronous

speed can also be controlled by selecting the number of poles for the subject motor.

The Hall Effect device 22 located on the motor in the place indicated in Figs. 1 and 2

can be mounted on swivel means to enable it to be moved backward and forward to change

the operation of the motor. In one position of the Hall Effect device 22, the motor can be

made to operate in one direction and in a different position, the motor can be made to operate

in the opposite direction of rotation.

The two separate Hall Effect devices could also be mounted on the circuit plate 12

and switch means can be provided to switch between one or the other in order to change the

direction of rotation.

Also shown in Fig. 3 is a motor breaking control means shown as switch 90 which is

5 connected across the capacitors C2 associated with the Hall Effect device SI . By closing the

switch 90 manually the motor can be braked or brought to a stop. The manual switch 90 can

be replaced by a switch 90 A connected across the same capacitors C2 but controlled by

external means such as by means in another circuit.

Fig. 7 is a block diagram of the electrical controls 100 for the subject motor. The

o electrical controls include a power switching circuit 102 which is connected in series between

an input alternating power current source and motor field coil 104. The motor field coil 104

can be mounted on a stator such as the laminated stator 24 shown in Figs. 1 and 2. The

power switching device 102 is controlled by an electronic control circuit 106 which in turn is

controlled by a sensor device such as the sensor 108 which may take the form of a Hall Effect

5 switch, an optical device and so forth. The circuit 106 controls the current flow through the

coil 104 and the operation of the motor. Current flow through the coil 104 in one direction

occurs when the one side of the line voltage is in its positive half cycle and the opposite side

of the line is in its negative half cycle, and current flows through the coil 104 in the opposite

direction when the line voltage on the same one side of the input is negative and the opposite

side of the line is positive. The direction of current flow is controlled by rotor position as

determined by the sensor such as by the Hall Effect sensor described above and by the

number of cycles of current that are allowed to flow in a given direction based on the rotor

speed which is also determined by the operation of the sensor.

Fig. 8 shows an alternating current input voltage source in the top diagram and it

shows the current flow through the coil in one direction during positive half cycles and

current flow through the coil in the opposite direction during the alternate half cycles.

Fig. 9 is a circuit diagram of one form of the control circuit 106 and the associated

5 sensor device. In Fig. 9 the alternating current input source 1 10 is connected across a diode

bridge circuit similar to the circuit 30 shown in Fig. 3. The stator coil 104 is connected

between the opposite sides of the input alternating current source 1 10 through controlled

rectifier circuits 1 12 and 1 14. The circuit 112 includes a silicon controlled rectifier 1 16 that

has its anode and cathode connected in parallel across a diode 118 and the controlled rectifier

10 1 14 includes a silicon controlled rectifier 120 in parallel with another diode 122. The gates of

the SCRs 116 and 120 are connected to control circuits which include respective diodes 124

and 126 and resistors 128 and 130. The opposite sides of the resistors 128 and 130 are

connected to the collector electrodes of respective transistors 132 and 134. The transistor 134

is a light sensitive transistor or phototransistor that responds to light impinging thereon from

15 a light emitting diode as will be described. The transistors 132 and 134 are connected into a

resistance circuit which biases the transistors into predetermined operating conditions which

enable the transistor 134 to conduct when light impinges thereon during alternate half cycles

of operation, and this enables the transistor 132 to conduct. The transistor 134 can be

substituted for by a Hall Effect device or a suitable MOSFET. Only one of the controlled

0 rectifier circuits 112 or 114 will be turned on at a time and during alternate half cycles to

control the conducting conditions of the transistors 132 and 134. The motor circuit shown in

Fig. 9 is similar in some respects to the motor circuits shown in Fig. 3 except that it requires

only one motor coil 104.

The circuit of Fig. 10 is similar to the circuit of Fig. 9 but differs therefrom in that the

5 coil 104A is connected across the alternating current source through a circuit which includes

back-to-back silicon controlled rectifiers 150 and 152. Each of the SCRs 150 or 152

conducts during alternate half cycles of the input energy source and the one that is conducting

establishes the direction of current flow through the coil 104A. For example, when the SCR

150 conducts, current will flow through the coil 104A in one direction and when the SCR 152

5 conducts current will flow through the coil 104A in the opposite direction. In the circuit of

Fig. 10, the gate electrodes of the SCRs 150 and 152 are connected respectively through

diode resistor circuits to one side of respective transistors 154 and 156. The transistor 156,

like the transistor 124, is responsive to light impinging thereon during alternate half cycles.

The circuit shown in Fig. 10 operates similarly to the circuit shown in Fig. 9 but represents a

o different embodiment.

Fig. 1 1 shows an alternate embodiment for the controlled rectifier circuits 1 12 and

1 14 in Fig. 9. For example, the circuit 112 can be replaced by a power MOSFET as shown in

Fig. 11 and the circuit 114 can similarly be replaced by a power MOSFET. In this case, each

of the replacement circuits will require an additional diode and resistor connected as shown.

5 Fig. 12 shows an alternate circuit for the SCRs 150 and 152 in circuit 10. In this case,

each of the SCRs is replaced by a power MOSFET connected as shown with an additional

diode and resistor.

It is also contemplated to connect a light emitting diode in the circuit between one

side of the input power source 110 and one side of the bridge circuit 30.

In Figs. 13 and 14 a circuit is shown connected into the lead on one side of the input

alternating current source. The circuit in this case includes a zener diode 160 connected in

parallel with a light emitting diode 162 and a resistor 164, the light produced by the light

emitting diode 162 during alternate current voltage will be projected onto the phototransistor

134 (or 156) to produce the desired action required to cause conduction therein. It will

become apparent that many other variations in circuit substitutions could be made in the

present device and as such as contemplated.

In Figs. 9 and 10 there are certain resistors that are showed connected across the

transistors 132, 134, 154 and 156. These resistors can be replaced by zener diodes such as

3.3 volt zener diodes connected with their anodes at the upper ends as shown of the respective

transistors. Such zener diodes may provide a somewhat more stable operating condition than

the resistors in certain applications.

Thus there has been shown and described several embodiments of a novel self starting

controllable synchronous motor which operates off of an alternating current input and fulfills

all of the objects and advantages sought therefor. It will be apparent, however, that many

changes, variations, modifications and other uses and applications for the subject device are

possible and all such changes, variations, modifications and other uses and applications

which do not depart from the spirit and scope of the invention are deemed to be covered by

the invention which is limited only by the claims which follows.