This invention is a controller for a multiple winding electrical motor such as is described in co-pending Inter- national Application Number PCT/US80/OO226 iled 03 March 1980 titled Multiple Windings Electrical Machines; this co pend.ing application is incorporated herein by this refer¬ ence. The present application provides for torque control of a. multiple windings electrical motor by operating var- ious numbers of electrical switches which energize various numbers of torque generating windings sets within the motor and by positioning a brushholder. The means of energizing and de-energizing these windings sets are individual electrical switches, which can be sequentially operated to preserve the advantages of a multiple windings electrical machine at all torque levels. The multiple windings electrical machine is uniquely controllable; the multiple windings electrical machine has multiple brushes in two groups contacting the commutator which provide multiple electrical control points. Each of these brushes can be energized, either directly or in series with a stator winding or portion thereof, through an electrical switch v/ith electrical energy derived from an electrical energy source. Thus, by operating these electrical switches the magnitude of torque generated by the multiple windings electrical motor can be controlled. Another as¬ pect of the multiple windings electrical motor torque control is use of the position of the brushholder to control the positions of the groups of multiple brushes and thereby control the direction and magnitude of torque generation. This invention includes the sequential oper¬ ation of individual electrical switches, singularly and cumulatively in a reversible sequence, to proceed in reg¬ ular increments to any desired torque generation within the capability of the machine. Singular and cumulative operation of the electrical sv/itches means they are oper¬ ated one at a time and that once operated in an increasing torque sequence or a decreasing torque sequence the switch will remain in that position and the next switch in the

sequence will be operated. This invention includes means for recovering electromagnetic energy from multiple wind¬ ings electrical motor open circuit armature windings when interrupted while contacted through coupled commutator segments by brushes of the two groups. This energy recov¬ ery means includes a half bridge circuit composed of a plurality of diodes which are coupled between each group brufeh and the electrical energy source terminals. The diodes are arranged to be back-biased until an open cir- cuit armature winding is interrupted, as above and thereby induces voltage which forward-biases certain diodes of the half bridge circuits coupled to commutator segments coupled to the ends of the interrupted open circuit arma¬ ture winding, and thereby electromagnetic energy associ- ated with the interrupted open circuit armature winding - is recovered and delivered to the electrical terminals.

BACKGROUND 0? THE INVENTION

1. PIELD OF THE INVENTION: This application is re- lated to motor speed and torque controllers for both pos¬ itive and negative torques, and to motor starters, and power output controllers. This invention relates to such controllers for brush-type machines-, and more particular¬ ly, to controllers for brush-type electrical machines of the type disclosed in the re erenced co-pending applica¬ tion titled Multiple Windings Electrical Machines.

2. BACKGROUND ART: Previous brush-type electrical machine controllers have used series resistance to cont¬ rol speed and torque and current, especially the excess- ive currents caused during the startup of series motors. The control of these brush-type machines is very import¬ ant in considering the application of these motors. There has been a lack of a reliably-operating, efficient controller for brush-type machines. The speed and torque o 2- series motor energized from a constant potential sup¬ ply can be controlled by inserting resistance in series with the supply line. Speed control for shunt and comp¬ ound motors can be obtained by inserting resistance in series with the armature circuit only. The stator field flux of shunt motors can be varied to control the spej

these motors, although special care is required to preven overspeeding of the motor is the shunt stator field flux becomes very weak. The speed of DC motors can be varied by varying the voltage applied to the motors; the Ward Leonard system of speed control is an example of varying the voltage applied to the DC motor. In the Ward Leonard system the adjustable output voltage from a motor-genera-

» or set is applied to the motor. Electric vehicle motor controllers use semiconductor chopper controllers as v/ell as electromechanical switches to connect resistors and batteries in various combinations to regulate electrical power input to the motor, which thereby control the motor output torque.

DISCLOSURE OF THE INVENTION

This invention provides control of the referenced multiple windings electrical motor by varying the number of torque generating winding sets of the motor which are energized. Each multiple windings electrical motor has a number of torque generating winding sets and the multiple windings electrical motor will operate efficiently with various numbers of the torque generating winding sets en¬ ergized, as long as the torque generating winding sets are energized and de-energized in a certain sequence v/ith res- pect to brush vacancies and the circumferential positions of the energized torque generating winding sets in the direction of armature movement, so as to maintain a rough mechanical balance of loads applied to the shaft bearings. Referring to Figure 1, a single multiple windings electrical motor torque generating winding set comprises a multiple windings electrical machine stator magnetomotive force means, such as split, stator winding 9-10 and 11-12, and a multiple windings electrical machine open circuit armature winding 60-61, which are positioned and inter- connected using brushes 13 and 1 and brushholder 82 as in a multiple windings electrical motor described in the ref¬ erenced application. . Each torque generating winding set is energized by electrical current flow through a torque generating set current control means. This current con- trol means may include any of a variety of electrical

switches, such as switches 1, 2, 3, 4, 5, 6, 7, and 8 or may include a means to control the commutator contact of the first brushes group brushes, 3* 21, 27, 33, and sec¬ ond brushes group brushes, 14, 22, 28, 34, associated with individual torque generating winding sets by lifting bru¬ shes from the commutator.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a linear representation of a two-pole multiple windings electrical motor controller in which the multiple windings electrical motor has four torque generating winding sets and the torque may be varied be¬ tween zero and maximum in four discrete steps by operating four, two-pole, single throw switches. The multiple wind- ings electrical motor linear representation uses the same drawing, simplifications used in the reference application and adds a brushholder. To simplify Figure 1 and repre¬ sent the multiple windings electrical motor in one view, the commutator 88 with commutator segments 72 through 81 and brushes 14, 22,. 8, 34*, 15, 13, 21, 27, 33, and 16 and connecting circuits and brushholder 82 and brush springs, one designated 93, are shown in an enlarged air gap be¬ tween the stator magnetic poles 70 and 71 and the magnetic armature 86. The preferred and practical electrical mach- ine construction in accordance with the reference applic¬ ation and the present application is to remove these ele¬ ments from this fictitious but simplifying air gap place¬ ment and place them adjacent to stator magnetic yoke 83 and armature magnetic member 86. Several figures showing the practical placement of the commutator and brushholder with brushes in a rotary multiple windings electrical mar- chine are shown in the reference application _* In Figure 1 dotted lines are used to represent stator or armature win¬ dings as they pass behind stator or armature magnetic mem- bers respectively.

Figure 2 shows a cam-operated controller for operatin the four switches of Figure 1 to provide torque control in a forward direction for the multiple windings electri¬ cal motor of Figure 1.

Figure 3 is a representation of a portion of the mul¬ tiple windings electrical motor of Figure 1 showing the brushholder shifted with respect to the stator poles to a neutral position in which the multiple windings electrical motor favors zero speed, and the multiple windings elect¬ rical motor does not generate either forward or reverse torque.

Figure 4 is a representation of a portion of the mul¬ tiple windings electrical motor of Figure 1 showing the brushholder shifted with respect to the stator poles to cause torque generation in the reverse direction, or oppo¬ site direction from Figure 1.

Figure 5 shows a cam-operated controller for operat¬ ing the four switches of Figure 1 to provide torque cont- rol in either the forward direction, represented by the ^' brushholder position in Figure 1, or the reverse direction represented by the brushholder position of Figure 4.

Figure 6 shows a linear representation of a four- pole multiple windings electrical motor controller in whi- ch the multiple windings electrical motor has eight tor¬ que .generating winding sets and the torque may be varied between zero and maximum in eight discrete steps by opera¬ ting eight, three-pole, single throw switches. The mult¬ iple windings electrical motor linear representation uses the same type of drawing simplifications used in the ref¬ erence application and Figure 1, except herein the commut¬ ator is designated 223, the commutator segments are desig¬ nated 177 through 196, the brushholder is designated 222, the brushes are designated 157 through 176, and one brush spring is designated 226. In Figure 6 dotted lines are used to represent stator or armature windings as they pass behind stator or armature magnetic members respectively.

DETAILED DESCRIPTION OF THE INVENTION This detailed description will explain: (1) the for¬ ward torque controller for a two stator pole multiple win¬ dings electrical motor, (2) the recovery of energy from armature windings not energized as a torque generating set, (3) the reverse torque controller for a two stator pole multiple windings electrical motor, (4) the forward qr _£ __

controller for the general, multiple stator pole pair mul¬ tiple windings electrical motor as represented by a two stator pole pair multiple windings electrical motor, and (5) the reverse torque controller for the general multiple windings electrical motor.

Consider a two-pole multiple windings electrical mot¬ or as represented in linear fashion in Figure 1 having two stator poles 70 and 71 with four split stator windings: 9- 10 and 11-12, 17-18 and 19-20, 23-24 and 25-26, and 29-30 and 31-32, and five open circuit armature windings: 60-61, 62-63, 64-65, 66-67, and 68-69. It will be recognized from the reference application that four stator windings is a number of stator windings chosen for the simplicity of pre¬ senting this multiple windings electrical motor controller and does not imply any multiple windings electrical motor *. or controller limitation at more or less than four stator windings; similarly, the five open circuit armature wind¬ ings are chosen or simplicity of presenting this multiple windings electrical motor controller and does not imply any multiple windings electrical motor or controller lim¬ itation at more or less than five open circuit armature windings. Figure 1 also shows: stator magnetic yoke 83, structural support 84-, key 85, brush spring 93, spring- loaded brushes 13, 14, 21, 22, 27, 28, 33, 3 , brushholder 82, magnetic, armature 86 v/ith teeth one of v/hich is 87, commutator 88 with conducting segments 72 through 81, me¬ chanical energy coupling 89, key 90, and brush vacancies 15 and 16. In a rotary multiple windings electrical motor the structural support 8*4 is the stator housing and the mechanical energy coupling 89 is the shaft, ^' and bearings position the shaft in the housing and allow the shaft to rotate within the housing; this construction is shown in the reference application. A brush vacancy is also defin¬ ed in the reference application, but in general terms a brush vacancy is a gap in the brushes v/hich allows the in¬ terruption and reversal of the open circuit armature wind¬ ings currents. The brushes are divided at brush vacancies into two groups: first brushes group brushes and second brushes group brushes. The brushes 13, 21, 27, and 33 are of the first group, and brushes 14, 22, 28, and 34 are of

the second group. The brushholder 82 is mechanically at¬ tached to the structural support 84, and the commutator 8 is mechanically attached to the mechanical energy coup¬ ling 89• Such a multiple windings electrical motor can be varied in torque in increments of approximately one- fourth of the maximum torque by energizing or de-energiz¬ ing the split stator windings one set at a time in a four- step sequence.

In Figure 1, the first step of this sequence is to energize the stator windings 9-10 and 11-12 from unidirec¬ tional voltage source 5 by closing electrical switches 1 and 2. The stator windings 9-10 and 11-12 connect to first and second brushes group brushes 13 and 14 respect¬ ively, which connect through various segments of the com- mutator 88 at various armature positions to energize open ^* circuit armature windings once removed contrary to the direction of torque generation from the brush vacancies 15 and 16, and from which the armature and open circuit . armature windings will move toward the brush vacancies in the forward, direction of torque generation—armature move¬ ment to the left in Figure 1.

In Figure 1, the second step of this sequence is to continue the first step and additionally energize the sta¬ tor windings 17-18 and 19-20 from the source 5 by closing electrical switches 3 and 4. The stator windings 17-18 and 19-20 connect to first and second brushes group brush¬ es 21 and 22 respectively, which connect through various segments of the commutator 88 at various armature positi¬ ons to energize open circuit armature windings twice re— moved from the brush vacancies contrary to the direction of torque generation.

In Figure 1, the third step of this sequence is to continue the second step and additionally energize the sta tor windings 23-24 and 25-26 from the source 51 by closing electrical switches 5 and 6. The stator windings 23-24 and 25-26 connect to first and second brushes group brush¬ es 27 and 28 respectively, which connect through various segments of the commutator 88 at various armature posit¬ ions to energize open circuit armature windings thrice re- moved from the brush vacancies contrary to the direction

of torque generation.

In Figure 1, the fourth step of this sequence is to continue the third step and additionally energize the sta¬ tor windings 29-30 and 31-32 from the source 5 by closing electrical switches 7 and 8. The stator windings 29-30 and 31-32 connect to first and second brushes group brush¬ es 33 and 3 - respectively which connect through various segώents of the commutator 88 at various armature posit¬ ions to energize open circuit armature windings fourth re- moved from the brush vacancies contrary to the direction of torque generation.

Notice that these four steps energize first and" sec¬ ond brushes group brushes at positions in a sequence with respect to the brush vacancies, which is a sequence dir- rected contrary to the torque generation direction. The - first step energizes the first and second brushes group brushes in the position once removed from the brush vacan¬ cies; the second step continues the first step and energ¬ izes the first ^" and second brushes group brushes ^" in the position twice removed from the brush vacancies; the third step continues the ^' second step and energizes the first and ^• second brushes group brushes in the position thrice remov¬ ed from the brush vacancies; and,, the fourth step continu¬ es the third step and energizes the first and second brush es group brushes in the position fourth removed from the brush vacancies.. At each step of this energizing sequence of the stator windings and these open circuit armature win dings energizing first and second brushes group brushes positions, the previously energized steps are retained as a new step is energized. Thus, the multiple windings ele¬ ctrical motor configuration is retained at each energized step.

The de-energization sequence is the reverse of the energizing sequence. Thus, from the condition of having all four open circuit armature windings energizing first and second brushes group brushes positions energized, the electrical switches 7 and 8 are opened to reduce to the condition of having only three open circuit armature wind¬ ings energizing first and second brushes group brushes positions energized; from the condition of having three

open circuit armature windings energizing first and second brushes group brushes positions energized, the electrical switches 5 and 6 are opened to reduce to the condition of having only two open circuit armature windings energizing first and second brushes group brushes positions energized from the condition of having two open circuit armature windings energizing first and second brushes group brushes positions energized, the electrical switches 3 and 4 are opened to reduce to the condition of having only one open circuit armature v/indings energizing first and second bru¬ shes group brushes position energized; and, to completely de-energize the multiple windings electrical motor, the electrical switches 1 and 2 are opened.

The recovery of electromagnetic energy from current interruption in open circuit armature windings while they are yet removed from the brush vacancies is done by diodes connected from each of brushes 13, 14, 21, 22, 27, 28, 33, and 34 to the positive and the negative terminals of the unidirectional voltage source 51• _. These diodes are desig- nated 35 through 50 in Figure 1. Each diode connected to the unidirectional voltage source 51 positive terminal is connected to that terminal by its cathode and its anode is connected to the brush. Each diode connected to the uni¬ directional voltage source 51 negative terminal is conn- ected to that terminal by its anode and its cathode is co¬ nnected to the brush. A diode pair such as 35 and 36 is called a half bridge circuit. This recovery of electro¬ magnetic energy takes place as follows under the following conditions. Assume the multiple windings electrical motor of Figure 1 is operating at the step-two torque level with two torque generating sets energized as described above; this will occur v/hen electrical switches 1, 2, 3, and 4 are closed. When the armature 87 with attached commutator 88 moves to the left from the Figure 1 shown position by one-half the commutator segments pitch, all the brushes

13, 14, 21, 22, 27, 28, 33, and 34 will straddle a gap be¬ tween some of the commutator segments 72 through 81 and all the open circuit armature windings will more-or-less share in-parallel the energizing current flov/ing through the stator windings energized by the electrical switches

1, 2, 3, and 4. When the armature moves farther in the same direction, the parallel energizing current in the ope circuit armature windings in the two un-energized open cir cuit armature windings energizing first and second brushes groups brushes positions thrice and fourth removed from th brush vacancies, will be interrupted by the commutator and commutator segments moving so the brushes no longer stradd le the gaps between the commutator segments; this current interruption will induce a large inductive kick voltage in the open circuit armature v/indings at the two un-energized open circuit armature v/indings energizing first and second brushes groups brushes positions connected to brushes 27, 28, 33, and 34-, which voltage is of opposite polarity to the voltage which caused the open circuit armature v/inding currents to flow; this opposite polarity voltage is cond- - ucted to the connected commutator segments and to the bru¬ shes 27, 28, 33, and 3 riding on these segments; through the diodes connected between these brushes and the unidir¬ ectional voltage source terminals, the electromagnetic en- ergy is recovered for re-use or storage in a manner simila to that described in the referenced application. This sam method of electromagnetic energy recovery from un-energize ' open circuit armature windings at energizing first and sec ond brushes groups brushes positions applies to a multiple windings electrical motor with any number of stator pole pairs.

If the foregoing is defined as controlling forward torque, then the control of reverse torque can be achieved by shi ting the brushholder 82 of Figure 1 by one stator pole pitch and operating the electrical switches in an in¬ verted sequence. The reverse torque generation conditions are established by shifting the brushholder 82 to the pos¬ ition shown in Figure 3 and then to the position shown in Figure 4. To make the shift from the Figure 1 to the Fig- ure 4 positions, the brushholder 82 has bearings between it and the structural support 84; the bearings are not shown in the Figures 1, 3, or 4. The brushholder 82 moves, shifts, so as to maintain the required operating brush spring loads between the brushes and the commu-ator seg- ments. The control of reverse directed torque at fo ιϋi. ^* -£-i

torque levels will be described by referring to Figures 1 4, and 5» The reverse torque generating sequence, the in verted sequence, starts with the brushholder 82 in the position shown in Figure 4 and with all the electrical sw tches 1, 2, 3, 4, 5, 6, 7, and 8 open, as shown in Figure 1.

In Figure 1 with brushholder 82 positioned as in Fig ure 4, the first step of the reverse sequence is to ener¬ gize the stator windings 29-30 and 31-32 from the unidir- ectional voltage source 51 by closing electrical switches 7 and 8. The stator windings 29-30 and 31-32 connect to first and second brushes groups brushes 35 and 3 respect ively, which connect through various segments of the com¬ mutator 88 at various armature positions to energize open circuit armature vindings once removed from the brush vac ancies 15 and 16, and from which the armature and open circuit armature windings v/ill move toward the brush vac¬ ancies in the reverse direction of torque generation—arm ature movement to the right in Figure 4. In Figure 1 v/ith brushholder 82 positioned as in Fig¬ ure 4, the second step of the reverse torque generating sequence is to continue the first step of this sequence and additionally energize the stator v/indings 23-24 and 25-26 from the source 51 by closing electrical switches 5 and 6. The stator windings 23-24 and 25-26 connect to first and second brushes groups brushes 27 and 28 respect¬ ively v/hich connect through various segments of the comm¬ utator 88 at various armature positions to energize open circuit armature windings twice removed from the brush va- cancies contrary to the direction of torque generation.

In Figure 1 v/ith brushholder 82 positioned as in Fig¬ ure 4, the third step of the reverse torque generating sequence is to continue the second step of this sequence and additionally energize the stator v/indings 17-18 and 19-20 from the source 51 by closing electrical switches 3 and 4. 'The stator windings 17-18 and 19-20 connect to first and second brushes groups brushes 21 and 22 respect¬ ively, v/hich connect through various segments of the com¬ mutator 88 at various armature positions to energize open circuit armature windings thrice removed from the bru≤

vacancies contrary to the direction of torque generation. In Figure 1 v/ith brushholder 82 positioned as in Fig¬ ure 4, the fourth step of the reverse torque generating sequence is to continue the third step of this sequence and additionally energize the stator windings 9-10 and 11—12 from the source 51 by closing electrical switches 1 and 2. The stator windings 9-10 and 11-12 connect to fir≤t and second brushes groups brushes 13 and 14 respect¬ ively, which connect through various segments of the com- mutator 88 at various armature positions to energize open circuit armature windings fourth removed from the brush vacancies contrary to the direction of torque generation.

In Figure 1 with brushholder 82 positioned as in Fig¬ ure 4, the decrease in reverse torque generation level is the inverse, or backing-down the sequence, of the above - sequence for increasing reverse torque generation level,, or magnitude.

Torque direction control in a multiple windings elec¬ trical motor can be done by (1) a brushholder shift, as described above, wherein the brushholder is shifted by one or an odd number of stator pole pitches, or (2) by winding current reversal wherein currents through stator windings are reversed with respect to currents through armature windings. The preferred of these two methods of reversal for the multiple windings electrical motor is by shifting the brushholder by one, or an odd number, of stator pole pitches in the direction of commutator movement. The win¬ ding current reversal is more complex in requiring additi¬ onal switchgear on a multiple windings electrical motor to effect the reversal. Shifting the brushholder requires bearings on the brushholder to maintain the brushholder concentric with the commutator and it requires flexible electrical connections to the brushes.

Figure 2 shows a push-knob operated cammed switch con- troller with a spring return for use in controlling the forward torque generated by a multiple windings electrical motor such as shown in Figure 1. The controller is shown in the zero torque position with all the electrical swi¬ tches open, and the cam 91 held to the left against its stop by the compression spring 92. When it is desired^g-QP£

increase the multiple windings electrical motor forward torque, the knob 90 is pressed, moving cam 91 to the right and compressing spring 92. The cam 91 is designed so the electrical switches operate in the sequence: 1 and 2, 3 and 4, 5 and 6, and 7 and 8, and that previously closed switches will continue closed as new ones are operated. Thus, pressing the knob 90 slowly until it causes the cam 91 to hit the right stop and slowly releasing knob 90 ca¬ uses the forward torque of the multiple v/indings electri- cal motor of Figure 1 to increase to the maximum torque in four steps and to decrease to zero torque through the same four steps in reverse order. Also notice that the torque may be increased to a less-than-maximum level and decrease from that level. Figure 5 shows a dual-cam switch controller operating one set of electrical switches with two cams 91 and 95 with separate push knobs to operate each cam and separate springs to return each cam; cam 91 is operated by knob 90 and returned by spring 92, and cam 95 is operated by knob 9 and returned by spring 96. The knob 90, cam 91, and spring 92 operate just as described for Figure 2 to cont¬ rol forward torque levels, when the brushholder 82 is in the position shown in Figure 1; the knob 94, cam 95, and spring 9 operate similarly to the knob 90, cam 91, and spring 92, but these control the reverse torque levels.

Before the knob 94, cam 95, and spring 96 can be operated efficiently in the multiple windings electrical motor fashion, the brushholder 82 must be shifted to the Figure 4 position. Once that has been done, pressing the knob 94 slowly to the cam 95 left stop and slowly releasing knob 94 causes the reverse torque of the multiple v/indings ele¬ ctrical motor of Figure 4 to increase to the maximum tor¬ que in four steps and to decrease to zero torque through the same four steps in reverse order. Operating the cam 95 in this manner causes the electrical switches to be op¬ erated in the inverted sequence described above for cont¬ rol of reverse torque.

Notice that the basic electrical switch required to switch each step of the torque varying se ue c for the Figure 1 multiple v/indings electrical uotor v/ith two sta-

tor poles, is a double-pole, single-throw (DPST) switch, such as switches 1 and 2 combined. The required basic electrical switch is different when the multiple windings electrical motor has more than two stator poles. When the multiple windings electrical motor has two or more pairs of stator poles, the basic electrical switch required at each step of the torque varying sequence is a three-pole, single-throw (3PST) switch. The controller for the mult¬ iple windings electrical motor with two or more pairs of stator poles will be described in the following section. The controllers for multiple windings electrical mo¬ tors with two or more pairs of stator poles are described in the following by referring to Figure 6. A multiple windings electrical motor with two stator poles does not have the generality of a multiple windings electrical mot¬ or v/ith two or more pairs of stator poles when a control¬ ler is being described. To explain the more general mult¬ iple windings electrical motor controller, consider a mul¬ tiple windings electrical motor consisting of two pair of stator poles with split-series stator windings as shown in Figure 6. The Figure 6 shows a multiple windings electri¬ cal motor with two stator pole pairs with four stator win¬ dings per pole pair and five open circuit armature wind¬ ings per pole pair. This combination is representative of multiple windings electrical motors with largers numbers of pairs of stator poles and with different numbers of stator windi gs and armature windings per pole pair. This Figure 6 multiple windings electrical motor can be varied from zero torque to maximum torque in eight increments by closing eight three-pole single-throw electrical switches in sequence. These electrical switch poles are designated 101 through 124. These electrical switches switch both ends of the split-series stator windings. The reason for switching both ends of the split-series stator v/indings which connect to the unidirectional voltage source 51 is to allow electromagnetic energy recovery using diodes con¬ nected to the source 51 electrical terminals from the un- energized open circuit armature windings energizing first and second brushes groups brushes positions; since all the brush positions may be un-energized at some torque lev

in forward or reverse, this means that diodes are so con¬ nected to all the brush positions. This electromagnetic energy recovery occurs, as described above for a two-pole multiple windings electrical motor, when a commutator se- gment or bar leaves a first or second brushes group brush while the commutator segment is yet removed from the brus vacancies. These segments are designated 177 through 196 in Figure 6. This electromagnetic energy recovery neces¬ sitates three electrical switch poles, because the negat- ive-connected end of the split-series stator winding used in a two or more repeatable section multiple windings ele ctrical motor is sometimes in the same repeatable section as the positive-connected end and sometimes in an adjac¬ ent repeatable section; see the referenced application for a detailed description of a repeatable section. Brie¬ fly, a repeatable section is a one pole pair machine; in Figures 1, 3, 4, and 6, the double-dashed lines mark re¬ peatable section boundaries; repeatable sections are join¬ ed at the stator structural support, stator magnetic yoke, mechanical energy coupling, magnetic armature, commutator, brushholder, and at the electrical terminals. To achieve electromagnetic energy recovery from the un-energized open circuit armature winding energizing first and second bru¬ shes groups brushes positions requires that a normally reverse-biased diode be connected, as described above for Figure 1, from each brush to each unidirectional voltage source 5 terminal. These diodes are not shown in Figure 6 to simplify and clarify the drawing; however, the diode brush connection points are indicated as unterminated wires along the brush-to-winding connections.

The Figure 6 controller torque-varying switches 101 through 124 are operated in groups of three by switch act¬ uators, similar to those shown in Figures 2 and 5, in eight steps to produce eight torque levels. The Figure 6 multiple windings electrical motor can be varied in incre¬ ments of about one-eighth of the maximum torque by energi¬ zing or de-energizing the torque generating winding sets of this motor one at a time in an eight step sequence. Figure 6 also shov/s: stator magnetic yoke 217, structural support 229, key 230, brush springs one designated

spring-loaded brushes 157 through 172, brushholder 222, magnetic armature 225 with teeth one of which is 224, com¬ mutator 223 with conducting segments 177 through 196, me¬ chanical energy coupling 227, key 228, and brush vacancies 173 through 176. The brushholder 222 is mechanically at¬ tached to the structural support 229, and the commutator 223 is mechanically attached to the mechanical energy coupling 227»

In Figure 6, the first step of the eight-step sequenc is to energize the stator windings 125-126, 127-128, and 149-150 by closing electrical switches 101, 102, and 103. The stator winding 125—126 connects to first brushes group brush 157, and the stator windings 127-128 and 149-150 co¬ nnect to second brushes group brushes 161 and 169 respect- ively; these brushes 157 with 161 or 157 with 169 connect through various segments of the commutator 223 at various armature positions to energize open circuit armature wind¬ ings once removed from the brush vacancies 175 and 174 or 175 and 176 contrary to the direction of torque generation In the Figure 1, the torque generating set position can be defined in relation to only two brush vacancies; however, in the more general multiple windings electrical motor of this Figure 6, the torque generating set position is defin ed in relation to three brush vacancies or two sets of bru sh vacancies; one brush vacancy is a central one and the other two are adjacent to the central one.

In Figure 6, the second step of this eight-step seq¬ uence is to continue the first step and additionally ener¬ gize the stator windings 141-142, 14*9-150, and 127-128 by closing electrical switches 10*4, 105, and 106. The stator winding 141-142 connects to first brushes group brush 165 and the stator windings 149-150 and 127-128 connect to second brushes group brushes 169 and 161 respectively; these brushes 165 with 169 or 165 with 161 connect through various segments of the commutator 223 at various armature positions to energize open circuit armature windings once removed from the brush vacancies 173 and 176 or 173 and 174- contrary to the direction of torque generation.

In Figure 6, the third step of this sequence is to continue the second step and additionally energize the—

the stator windings 129-130, 131-132, and 151-152 by clos ing electrical switches 107, 108, and 109. The stator winding 129-130 connects to first brushes group brush 158 and the stator windings 131-132 and 151-152 connect to second brushes group brushes 162 and 170 respectively; these brushes 158 with 162 or 158 with 170 connect through various segments of the commutator 223 at various armature positions to energize open circuit armature v/indings twice removed from the brush vacancies 175 and 174 or 175 and 176 contrary to the direction of torque generation.

In Figure 6, the fourth step of this sequence is to continue the third step and additionally energize the sta¬ tor windings 143-144, 151-152, and 131-132 by closing ele¬ ctrical switches 110, 111, and 112. The stator winding 143-144* connects to first brushes group brush 166, and the stator windings 151-152 and 131-132 connect to second bru¬ shes group brushes 170 and 162 respectively; these brushes 166 with 170 or 166 v/ith 162 connect through various seg¬ ments of the commutator 223 at various armature positions to energize open circuit armature windings tv/ice removed from the brush vacancies 173 and 176 or 173 and 17^ cont¬ rary to the direction of torque generation.

In Figure 6, the fifth step of this sequence is to continue the fourth step and additionally energize the stator windings 133-134, 135-136, and 153-154- by closing electrical switches 113, 114, and 115. The stator winding 133-134 connects to first brushes group brush 159, and the stator windings 135-136 and 153-154 connect to second bru¬ shes group brushes 163 and 171 respectively; these brushes 159 with 163 or 159 v/ith 171 connect through various seg¬ ments of the commutator 223 at various armature positions to energize open circuit armature windings thrice removed from the brush vacancies 175 and 174 or 175 and 176 cont¬ rary to the direction of torque generation. I Figure 6, the sixth step of this sequence is to continue the fifth step and additionally energize the stator windings 145-146, 153-154, and 135-136 by closing electrical switches 116, 117, and 118. The stator -.vinding 145-146 connects to first brushes group brush 167, and the stator v/indings 153-154 and 135-136 connect to second . ε&--y

shes group brushes 171 and 163 respectively; these brushes

167 with 171 or 167 with 163 connect through various seg¬ ments of the commutator 223 at various armature positions to energize open circuit armature windings thrice removed from the brush vacancies 175 and 176 or 173 and 174 cont- rary to the direction of torque generation.

In Figure 6, the seventh step of this sequence is to continue the sixth step and additionally energize the stator windings 137-138, 139-140, and 155-156 by closing electrical switches1l9, 120, and 121. The stator winding 137-138 connects to first brushes group brush 160, and the stator windings 139-140 and 155-156 connect to second bru¬ shes group brushes 164 and 172 respectively; these brushes 160 with 164 or 160 with 172 connect through various seg- ments of the commutator 223 at various armature positions to energize open circuit armature w ndings fourth removed from the brush vacancies 175 and 174 or 175 and 176 cont¬ rary to the direction of torque generation.

In Figure 6, the eighth step of this sequence is to continue the seventh step and additionally energize the stator windings 147-148, 155-156, and 139-140 by closing electrical switches 122, 123, and 124. The stator winding 147-148 connects to first brushes group brush 168, and the stator windings 155-156 and 139-140 connect to second bru- shes group brushes 172 and 164 respectively; these brushes

168 with 172 and 168 with 164 connect through various seg¬ ments of the commutator 223 at various armature positions to energize open circuit armature windings fourth removed from the brush vacancies 173 and 176 or 173 and 174 cont- rary to the direction of torque generation. This complete the eight-step energizing sequence for the Figure 6 mult¬ iple windings electrical motor to reach its maximum tor¬ que generating level.

The de-energizing sequence to reach the zero torque level from the maximum torque level in the Figure 6 motor is the reverse of the energizing sequence described above.

The eight-step de-energizing sequence by step condition proceeds: eight, seven, six, five, four, three, two, one, and zero. Throughout all the above energizing and de-ener gizing steps, the multiple windings electrical

configuration is retained at each energized step.

The control of reverse torque in the general multiple windings electrical motor as represented by the Figure 6 configured motor is done similarly to that control of rev- erse torque described or the Figure 1 motor with the brushholder 82 shifted as in Figure 4*. The brushholder 222 is shifted by one, or an odd number of, stator pole pitch(es), and the electrical switches are operated in an inverted eight step sequence to energize to maximum rev- erse torque as follows: step one: switches 124, 123, and 122; step two: switches 121, 120, and 119; step three: switches 118, 117* and 116; step four: switches 115, 114, and 113; step five: switches 112, 111, and 110; step six: switches 109, 108, and 107; step seven: switches 106, 105, and 104; step eight: switches 103, 102, and 101. To de¬ crease to zero torque from the maximum reverse torque generation, just back-down the above eight step sequence.

Again notice that the torque in either reverse or forward generating sequences may be increased or decreased from any intermediate torque level.

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