CA1299641C - Cycloconverter drive utilizing a dual stator motor - Google Patents
Cycloconverter drive utilizing a dual stator motorInfo
- Publication number
- CA1299641C CA1299641C CA000601476A CA601476A CA1299641C CA 1299641 C CA1299641 C CA 1299641C CA 000601476 A CA000601476 A CA 000601476A CA 601476 A CA601476 A CA 601476A CA 1299641 C CA1299641 C CA 1299641C
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- Canada
- Prior art keywords
- winding
- rotor
- group
- phase
- converters
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M5/25—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
- H02M5/27—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means for conversion of frequency
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/022—Synchronous motors
- H02P25/03—Synchronous motors with brushless excitation
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
Case 3029 A CYCLOCONVERTER DRIVE UTILIZING A DUAL
STATOR MOTOR
Abstract of the Disclosure A drive system which has a three phase synchronous motor for providing the driving power has a rotor with its rotor winding connected to a source of controlled current. Each of the three phases in the stator winding has a first portion and a second portion. The first portions of the three phase windings and the second portions of the three phase windings are arranged in parallel as separate three phase winding groups. There is a controlled power source, such as a converter, for each winding portion with each power source being connected to a respective winding portion. For the same output, the voltage at the motor terminals is less than for a motor with a standard three phase winding. If there is a fault associated with a power source connected with a first winding portion, the motor may be run at reduced power using only the second winding portions and the power sources connected thereto.
STATOR MOTOR
Abstract of the Disclosure A drive system which has a three phase synchronous motor for providing the driving power has a rotor with its rotor winding connected to a source of controlled current. Each of the three phases in the stator winding has a first portion and a second portion. The first portions of the three phase windings and the second portions of the three phase windings are arranged in parallel as separate three phase winding groups. There is a controlled power source, such as a converter, for each winding portion with each power source being connected to a respective winding portion. For the same output, the voltage at the motor terminals is less than for a motor with a standard three phase winding. If there is a fault associated with a power source connected with a first winding portion, the motor may be run at reduced power using only the second winding portions and the power sources connected thereto.
Description
6 ~
- 1 - Case 3029 A CYCLOCONVERTER D IVE UTILIZING A DUAL
5 ATOR_MOTOR
Backqxound of the Invention This invention relates to a cycloconverter drive system, and in particular it relates to a cycloconverter drive system which has a dual stator motor.
Drive systems which use a cycloconverter to provide power to a motor are well known. For example, the article "Electrical Aspects of the 8750 hp Gearless Ball-Mill Drive at St.Lawrence Cement Company", Allan et al, IEEE Trans. Ind. Appl.,vol. lA-ll, pp.681-687, Nov./Dec. 1975, describes such a drive.
Frequently these drive systems use six pulse cycloconverters to provide three phase power to a synchronous motor. However, it i5 known to connect two converters in series ~o provide power for each phase of a three phase synchronous motor. It is known to connect one converter in each pair of series connected converters to the power system side or source side through a transformer having a delta connected primary and a delta connected secondary, while the other converter in the pair is connected through a transformer having a delta connected primary and a wye connected secondary~ Thus, for the three phases there ' .. .
'~
- 1 - Case 3029 A CYCLOCONVERTER D IVE UTILIZING A DUAL
5 ATOR_MOTOR
Backqxound of the Invention This invention relates to a cycloconverter drive system, and in particular it relates to a cycloconverter drive system which has a dual stator motor.
Drive systems which use a cycloconverter to provide power to a motor are well known. For example, the article "Electrical Aspects of the 8750 hp Gearless Ball-Mill Drive at St.Lawrence Cement Company", Allan et al, IEEE Trans. Ind. Appl.,vol. lA-ll, pp.681-687, Nov./Dec. 1975, describes such a drive.
Frequently these drive systems use six pulse cycloconverters to provide three phase power to a synchronous motor. However, it i5 known to connect two converters in series ~o provide power for each phase of a three phase synchronous motor. It is known to connect one converter in each pair of series connected converters to the power system side or source side through a transformer having a delta connected primary and a delta connected secondary, while the other converter in the pair is connected through a transformer having a delta connected primary and a wye connected secondary~ Thus, for the three phases there ' .. .
'~
- 2 - Case 3029 are six converters forming a twelve pulse arrangement and, because the phase of the delta connected secondary is shifted 30 degrees with respect to the wye connected secondary, it is po~sible to virtually eliminate the fifth and seventh harmonics from the source side. It is, of course, desirable to keep the harmonics as low as possible to minimize the voltage distortion on the power system. Consequently a drive arrangemen~ using two series connected converters in this manner for each phase is a desirable arrangement.
There are, however, some disadvantages to these prior art, twelve pulse, drive systems with pairs of series connected converters. If one of the bridges (i.e. converters) should become inoperable, then the drive must be shut down. It is not feasible to operate a synchronous motor with one phase supplied with half the voltage provided to the other two phases. In addition, if a fault should occur across the motor terminals, for example, if a commutation failure should occur in the converters supplying one phase winding, a high torque is produced on the shaft. The shaft and any shaft couplings must be desiqned to withstand this large torque.
Summary of the Invention The drive system according to the invention provides a split winding arrangement for each phase winding of the motor. That is, each phase has two windings or winding portions. Thus, there are twice the number of windings in the motor. The pairs of converters used to provide power to each phase are not connected in series as in the prior art, but rather each converter is connected to a respective one of the windings or winding portions. This arrangement permits the use o~ lower voltages across each winding (each phase now having two windings, that is, two winding - ~ - Case 3029 portions), and because of the lower voltages involved at the terminals, the terminals and associated wiring requires less separation and less insulation.
Another advantage of the split winding arrangement is a reduced tendency for a fault to spread. When two converters are connected in series and a commutation fault occurs in one converter, there is a resulting high current which tends to induce a fault in the other converter. This is not as likely to happen with the split winding arrangement because each converter is connected to its respective split winding or winding portion and has no direct interconnection with any other converter.
With such a split winding arrangement, a fault in any converter is less likely to spread to another converter and is thus likely to affect only half a phase winding. If continued operation is desired, corresponding converters in the other two phases may be shut down and the motor operated under half power (a split winding portion in each phase being supplied with power from a respective converter).
It will also be apparent that a fault in any converter will result in a reduced fault shaft torque when compared to a drLve system having series connected converters.
It is therefore an object of the invention to provide a three phase motor drive system having a pair of converters for each motor phase where each motor phase winding is split and each winding portion is connected to a respective converter.
It is another object of the invention to provide a drive system having a synchronous motor with a split winding for each phase, and each part or portion of the split winding is connected to its own supply whereby the voltage across each winding may be - 4 - Case 3029 reduced.
It is a further object of the invention to provide a drive system with a motor having separately powered split phase windings that result in a reduction of fault shaft torque caused by a supply fault.
Accordingly there is provided a drive system comprising a synchronous motor having ~ stator and a rotor, the rotor having a rotor winding, the stator having windings for each of three phases, each phase winding having a first winding portion and a second winding portion, a converter for each winding portion, each converter being connected to a respective winding portion to provide power thereto, means for providing power to the rotor winding, and means for controlling each of the converters to provide power to the respective winding poxtion at a desired frequency and current.
Brief Description of the Drawinqs The invention will be described with reference to the accompanying drawings, in which The single figure (Fig. 1) of drawings is a simplified block schematic drawing showing the invention.
Description of the Preferred Embodiment Referring to the drawing there is shown a simplified block schematic drawing of the invention in which a synchronous motor 10 has a rotor 11 and a stator 12. The rotor 11 has a shaft 14 which is connected to drive a load (not shown). The rotor 11 has a rotor winding 15, indicated schematically. Rotor winding 15 is connected by conductors 16 to a rectifier 17. The rectifier 17 is, in turn, connected by conductors 18 to a brushless exciter 20. The brushless exciter 20, as is known, may be mounted on shaft 14 to rotate with rotor 11 and provide power to , ..
;6 ~
- 5 - Case 3029 rectifier 17. The rectifier 17 rectifies the power from exciter 2~ to provide DC power to rotor winding 15.
It will, o~ course, be apparent that instead of a brushless exciter 20, a separate slip ring type exciter could be used to provide a controlled current to the rotor winding 15.
Synchronous motor 10 is a three phase motor and the stator 12 has a split winding for each phase.
That is, each phase winding has two portions, and each winding portion has terminals for separate connection to a source of power. For ease of drawing, the stator windings are shown schematically above and below the synchronous motor 10 at A and B. Thus, there are three windings 21, 22 and 23 - one for each phase -and each phase winding has a portion A a~d a portion B. The first phase winding thus has portions or split winding portions (or more simply windings) 21A and 21B. Similarly the second phase has winding portions or windinqs 22A and 22B. The third phase has winding portions or windings 23A and 23B. There is a neutral connection 29A for windings 21A, 22A and 23A.
Similarly there is a neutral connection 29B for windings 21B, 22B and 23B.
Each winding portion or winding 21A, 21B, 22A, 22B, 23A, and 23B is connected to a respective converter 25A, 25B, 26A, 26B, 27A and 27B, and receives its power from the respective converter.
Thus, converter 25A is connected through switch 28 and conductor 30 to one end of winding 2lA and by conductor 31 to a neutral bus 24A. Similarly converter 25B is connected through switch 32 and by conductor 33 to one end of winding 2lB, and by conductor 34 to a neutral bus 24B. In a like manner, converter 26A is connected through switch 35 and by .
- . ~ .
" ' ,' ' .. ' ' ' :
.
. .
.
- 6 - Case 3029 conductor 36 to one end of winding 2ZA, and by conductor 37 to neutral bus 24A. Converter 26B is connected through switch 38 and by conductor 40 to one end of winding 22B, and by conductor 41 to neutral bus 24B. Converter 27A is connected through switch 42 and by conductor 43 to one end of winding 23A, and is connected by conductor 44 to neutral bùs 24A.
Converter 27B is connected through switch 45 and by conductor 46 to one end of winding 23B, and is connected by conductor 47 to neutral bus 24B.
It will be seen that converters 25A, 25B, 26A, 26B, 27A and 27B comprise a twelve pulse cycloconverter. The switches 28, 32, 35, 38, 42 and 45, which are conveniently remotely controlled switches, make it possible to switch any winding or winding portion out of the circuit. Thus, if there is a problem with one converter, or with one winding, it can be isolated. If a converter in the A group should fail, all the A converters can be switched out of the circuitry which feeds the motor, and the motor can run on the B converters and B windings at half power.
There are six current sensors 50, 51, 52, 53, 54 and 55 which provide signals via cable 56 representing the currents in respective 25 conductors 30, 33, 36, 40, 43 and 46. Cable 56 is connected to a flux and cycloconverter control circuit 57 so that signals representing the current output from each converter 25A through 27B are available at the flux and cycloconverter control circuit 57. A
rotor shaft position sensor 58 is conveniently mounted to the rotor shaft. A conductor 60 connects the position sensor 58 to flux and cycloconverter control circuit 57 to provide thereto a signal representing rotor position and from this signal shaft speed can also be determined. In addition, there are aontrol - 7 - Case 3029 inputs indicated at 61. The control signals at input 61 may, for example, represent desired vperating parameters such as speed and power. The flux and cycloconverter control 57 provides timiny signals on cable 62 for converters 2sA through Z7B. The circuit 57 also provides, on conductor 63 a signal to field control circuit 64. circuit 64 provides over conductor 65 power which controls the output of brushless e~citer 20 and hence controls the current in field winding 15.
A main bus 66 provides the power for the drive system through a breaker 67 to a local bus 6~.
The primary windings 70 - 75 of respective transformers 76 - 81 are delta connected to the bus 68. The transformers 76 - 81 have respective secondary windinys 82 - 87. The secondary windings 82, 84 and 86 are delta connected and the secondary windings 83, ~35 and 87 are wye connected. The secondary windings 82 - 87 are connected respectively to provide power to converters 25A through 27B.
It is known, to reduce the ~ifth and seventh harmonics using a 30 degree phase difference (at fundamental frequency) between the delta connected secondaries and the wye connected secondaries.
Because of the arrangement of transformers in this invention, it is convenient to use this feature in the present invention.
It will be apparent to those skilled in the art that an equivalent arrangement could have all the secondaries delta connected with alternate primaries wye connected to obtain a desired phase shift for the same harmonic cancellation in a twelve pulse cycloconverter.
It will, of course, also be apparent that the primary windings 70 and 71 could be combined as a single primary winding in a single transformer with ."3t~ ~
\
- 8 - Case 3029 two secondary windings ~2 and 83. Likewise primary windings 72 and 73, and the primary windings 74 and 75, could be combined.
The normal operation of the cycloconverter drive of this invention is similar to other cycloconverter drives utilizing a twelve pulse converter. ~he timiny of the firing of the thyristors in the converters 25A through 27B provides a desired frequency and current for the stator windings 21A
through 23B. ~he current in the stator windings is monitored by current sensors 50 - 55 and signals representing the sensed currents are fed back to the flux and cycI`oconverter control circuit 57. The rotor shaft position sensor 58 senses shaft position and a signal representing this is fed back to flux and cycloconverter control circuit 57 providing information on shaft position and rotational speed.
The firing of the thyristors can be controlled to provide a desired stator current and the rotor field can be controlled to provide a d~sired flux. The synchronous motor is thus controlled in accordance with input parameters at input 61.
It should be noted that the voltage across each winding (or winding portion) is less than in the prior art because the winding is half the size of the prior art winding for a similar size drive. It is thus easier to insulate and/or isolate each winding terminal and associated conductors. If a fault should occur, then the operation of the drive system of this invention is different and provides advantages over the prior art. For example, if a fault should occur in converter 25A and this fault continues, it is not necessary to shut down the drive system completely as would be the case in the prior art with pairs of series connected converters. Rather, converter 25A
- 9 - Case 3029 can be isolated by opening switch 28. Converters 26A
and 27A can also be switched out of operation by opening respective switches 35 and 42. The drive system can continue operating, but at half power, using converters 25B, 26B and 27B.
In a prior art system having pairs of series connected converters, if a commutation fault should occur in one of the converters~ there is a tendency for this fault to sp~.ead to the other converter in the series connected pair. Because the drive arrangement of this invention does not have series connected pairs of converters, such tendency is considerably reduced.
In the operation of the drive system of this invention, the shaft torque caused by a fault in one converter is less than the shaft torque in a prior art system because the current only involves half the winding.
It is believed the preceding description provides a complete understanding of the invention.
There are, however, some disadvantages to these prior art, twelve pulse, drive systems with pairs of series connected converters. If one of the bridges (i.e. converters) should become inoperable, then the drive must be shut down. It is not feasible to operate a synchronous motor with one phase supplied with half the voltage provided to the other two phases. In addition, if a fault should occur across the motor terminals, for example, if a commutation failure should occur in the converters supplying one phase winding, a high torque is produced on the shaft. The shaft and any shaft couplings must be desiqned to withstand this large torque.
Summary of the Invention The drive system according to the invention provides a split winding arrangement for each phase winding of the motor. That is, each phase has two windings or winding portions. Thus, there are twice the number of windings in the motor. The pairs of converters used to provide power to each phase are not connected in series as in the prior art, but rather each converter is connected to a respective one of the windings or winding portions. This arrangement permits the use o~ lower voltages across each winding (each phase now having two windings, that is, two winding - ~ - Case 3029 portions), and because of the lower voltages involved at the terminals, the terminals and associated wiring requires less separation and less insulation.
Another advantage of the split winding arrangement is a reduced tendency for a fault to spread. When two converters are connected in series and a commutation fault occurs in one converter, there is a resulting high current which tends to induce a fault in the other converter. This is not as likely to happen with the split winding arrangement because each converter is connected to its respective split winding or winding portion and has no direct interconnection with any other converter.
With such a split winding arrangement, a fault in any converter is less likely to spread to another converter and is thus likely to affect only half a phase winding. If continued operation is desired, corresponding converters in the other two phases may be shut down and the motor operated under half power (a split winding portion in each phase being supplied with power from a respective converter).
It will also be apparent that a fault in any converter will result in a reduced fault shaft torque when compared to a drLve system having series connected converters.
It is therefore an object of the invention to provide a three phase motor drive system having a pair of converters for each motor phase where each motor phase winding is split and each winding portion is connected to a respective converter.
It is another object of the invention to provide a drive system having a synchronous motor with a split winding for each phase, and each part or portion of the split winding is connected to its own supply whereby the voltage across each winding may be - 4 - Case 3029 reduced.
It is a further object of the invention to provide a drive system with a motor having separately powered split phase windings that result in a reduction of fault shaft torque caused by a supply fault.
Accordingly there is provided a drive system comprising a synchronous motor having ~ stator and a rotor, the rotor having a rotor winding, the stator having windings for each of three phases, each phase winding having a first winding portion and a second winding portion, a converter for each winding portion, each converter being connected to a respective winding portion to provide power thereto, means for providing power to the rotor winding, and means for controlling each of the converters to provide power to the respective winding poxtion at a desired frequency and current.
Brief Description of the Drawinqs The invention will be described with reference to the accompanying drawings, in which The single figure (Fig. 1) of drawings is a simplified block schematic drawing showing the invention.
Description of the Preferred Embodiment Referring to the drawing there is shown a simplified block schematic drawing of the invention in which a synchronous motor 10 has a rotor 11 and a stator 12. The rotor 11 has a shaft 14 which is connected to drive a load (not shown). The rotor 11 has a rotor winding 15, indicated schematically. Rotor winding 15 is connected by conductors 16 to a rectifier 17. The rectifier 17 is, in turn, connected by conductors 18 to a brushless exciter 20. The brushless exciter 20, as is known, may be mounted on shaft 14 to rotate with rotor 11 and provide power to , ..
;6 ~
- 5 - Case 3029 rectifier 17. The rectifier 17 rectifies the power from exciter 2~ to provide DC power to rotor winding 15.
It will, o~ course, be apparent that instead of a brushless exciter 20, a separate slip ring type exciter could be used to provide a controlled current to the rotor winding 15.
Synchronous motor 10 is a three phase motor and the stator 12 has a split winding for each phase.
That is, each phase winding has two portions, and each winding portion has terminals for separate connection to a source of power. For ease of drawing, the stator windings are shown schematically above and below the synchronous motor 10 at A and B. Thus, there are three windings 21, 22 and 23 - one for each phase -and each phase winding has a portion A a~d a portion B. The first phase winding thus has portions or split winding portions (or more simply windings) 21A and 21B. Similarly the second phase has winding portions or windinqs 22A and 22B. The third phase has winding portions or windings 23A and 23B. There is a neutral connection 29A for windings 21A, 22A and 23A.
Similarly there is a neutral connection 29B for windings 21B, 22B and 23B.
Each winding portion or winding 21A, 21B, 22A, 22B, 23A, and 23B is connected to a respective converter 25A, 25B, 26A, 26B, 27A and 27B, and receives its power from the respective converter.
Thus, converter 25A is connected through switch 28 and conductor 30 to one end of winding 2lA and by conductor 31 to a neutral bus 24A. Similarly converter 25B is connected through switch 32 and by conductor 33 to one end of winding 2lB, and by conductor 34 to a neutral bus 24B. In a like manner, converter 26A is connected through switch 35 and by .
- . ~ .
" ' ,' ' .. ' ' ' :
.
. .
.
- 6 - Case 3029 conductor 36 to one end of winding 2ZA, and by conductor 37 to neutral bus 24A. Converter 26B is connected through switch 38 and by conductor 40 to one end of winding 22B, and by conductor 41 to neutral bus 24B. Converter 27A is connected through switch 42 and by conductor 43 to one end of winding 23A, and is connected by conductor 44 to neutral bùs 24A.
Converter 27B is connected through switch 45 and by conductor 46 to one end of winding 23B, and is connected by conductor 47 to neutral bus 24B.
It will be seen that converters 25A, 25B, 26A, 26B, 27A and 27B comprise a twelve pulse cycloconverter. The switches 28, 32, 35, 38, 42 and 45, which are conveniently remotely controlled switches, make it possible to switch any winding or winding portion out of the circuit. Thus, if there is a problem with one converter, or with one winding, it can be isolated. If a converter in the A group should fail, all the A converters can be switched out of the circuitry which feeds the motor, and the motor can run on the B converters and B windings at half power.
There are six current sensors 50, 51, 52, 53, 54 and 55 which provide signals via cable 56 representing the currents in respective 25 conductors 30, 33, 36, 40, 43 and 46. Cable 56 is connected to a flux and cycloconverter control circuit 57 so that signals representing the current output from each converter 25A through 27B are available at the flux and cycloconverter control circuit 57. A
rotor shaft position sensor 58 is conveniently mounted to the rotor shaft. A conductor 60 connects the position sensor 58 to flux and cycloconverter control circuit 57 to provide thereto a signal representing rotor position and from this signal shaft speed can also be determined. In addition, there are aontrol - 7 - Case 3029 inputs indicated at 61. The control signals at input 61 may, for example, represent desired vperating parameters such as speed and power. The flux and cycloconverter control 57 provides timiny signals on cable 62 for converters 2sA through Z7B. The circuit 57 also provides, on conductor 63 a signal to field control circuit 64. circuit 64 provides over conductor 65 power which controls the output of brushless e~citer 20 and hence controls the current in field winding 15.
A main bus 66 provides the power for the drive system through a breaker 67 to a local bus 6~.
The primary windings 70 - 75 of respective transformers 76 - 81 are delta connected to the bus 68. The transformers 76 - 81 have respective secondary windinys 82 - 87. The secondary windings 82, 84 and 86 are delta connected and the secondary windings 83, ~35 and 87 are wye connected. The secondary windings 82 - 87 are connected respectively to provide power to converters 25A through 27B.
It is known, to reduce the ~ifth and seventh harmonics using a 30 degree phase difference (at fundamental frequency) between the delta connected secondaries and the wye connected secondaries.
Because of the arrangement of transformers in this invention, it is convenient to use this feature in the present invention.
It will be apparent to those skilled in the art that an equivalent arrangement could have all the secondaries delta connected with alternate primaries wye connected to obtain a desired phase shift for the same harmonic cancellation in a twelve pulse cycloconverter.
It will, of course, also be apparent that the primary windings 70 and 71 could be combined as a single primary winding in a single transformer with ."3t~ ~
\
- 8 - Case 3029 two secondary windings ~2 and 83. Likewise primary windings 72 and 73, and the primary windings 74 and 75, could be combined.
The normal operation of the cycloconverter drive of this invention is similar to other cycloconverter drives utilizing a twelve pulse converter. ~he timiny of the firing of the thyristors in the converters 25A through 27B provides a desired frequency and current for the stator windings 21A
through 23B. ~he current in the stator windings is monitored by current sensors 50 - 55 and signals representing the sensed currents are fed back to the flux and cycI`oconverter control circuit 57. The rotor shaft position sensor 58 senses shaft position and a signal representing this is fed back to flux and cycloconverter control circuit 57 providing information on shaft position and rotational speed.
The firing of the thyristors can be controlled to provide a desired stator current and the rotor field can be controlled to provide a d~sired flux. The synchronous motor is thus controlled in accordance with input parameters at input 61.
It should be noted that the voltage across each winding (or winding portion) is less than in the prior art because the winding is half the size of the prior art winding for a similar size drive. It is thus easier to insulate and/or isolate each winding terminal and associated conductors. If a fault should occur, then the operation of the drive system of this invention is different and provides advantages over the prior art. For example, if a fault should occur in converter 25A and this fault continues, it is not necessary to shut down the drive system completely as would be the case in the prior art with pairs of series connected converters. Rather, converter 25A
- 9 - Case 3029 can be isolated by opening switch 28. Converters 26A
and 27A can also be switched out of operation by opening respective switches 35 and 42. The drive system can continue operating, but at half power, using converters 25B, 26B and 27B.
In a prior art system having pairs of series connected converters, if a commutation fault should occur in one of the converters~ there is a tendency for this fault to sp~.ead to the other converter in the series connected pair. Because the drive arrangement of this invention does not have series connected pairs of converters, such tendency is considerably reduced.
In the operation of the drive system of this invention, the shaft torque caused by a fault in one converter is less than the shaft torque in a prior art system because the current only involves half the winding.
It is believed the preceding description provides a complete understanding of the invention.
Claims (5)
1. A drive system comprising, a synchronous motor having a rotor and a stator, said rotor having a rotor winding, means providing a controlled current to said rotor winding, said stator having windings for each of three phases, each winding having a first winding portion and a second winding portion, a converter for each winding portion, each converter being connected to a respective winding portion, and means for controlling each of said converters to provide power to the respective winding portion at a desired frequency and current.
2. A drive system as defined in claim 1 and further comprising a switch means for each converter for isolating a respective converter from its respective winding portion.
3. A drive system as defined in claim 1 in which said first winding portions of said three phases and said second winding portions of said three phases are each connected in a wye arrangement.
4. A drive system comprising, a synchronous motor having a stator and a rotor, said rotor being mounted for rotation within said stator, said rotor having a rotor winding and having an output drive shaft, means connected with said rotor winding for providing a controlled current to said rotor winding, said stator having a first, second and third phase winding, each of said first, second and third - 11 - Case 3029 phase windings having a first portion and a second portion in phase with one another, said first portions of said first, second and third phase windings being connected in a wye arrangement to form a first winding group, said second portions of said first, second and third phase windings being connected in a wye arrangement to form a second winding group, a first group and a second group of switch means, each group comprising three switch means, a first group and a second group of converters, each group comprising three converters, each converter having a first and second output terminal, the free end of each first portion of said first, second and third phase windings being connected through a respective switch means of said first group of switch means to a first terminal of a respective one of said first group of converters, the second terminal of said first group of converters being connected to a first neutral bus, the free end of each second portion of said first, second and third phase windings being connected through a respective switch means of said second group of switch means to a first terminal of a respective one of said second group of converters, the second terminal of said second group of converters being connected to a second neutral bus, first sensor means for sensing the current provided for each portion of said first, second and third phase windings and providing a signal representing each sensed current, second sensor means for sensing the position of said rotor shaft and for providing a rotor position signal representing the sensed position, and a flux and converter control circuit for receiving said signals representing each sensed - 12 - Case 3029 current and said rotor position signal, and providing control signals to each converter and to said means connected to said rotor winding, for controlling the current to said first and second portions of said first, second and third phase windings and to said rotor winding in accordance with desired parameters for controlling said motor, said motor being capable of operation at reduced power with only said first group of converters providing current to said first portions of said first, second and third phase windings in response to a fault in any converter of said second group of converters.
5. A synchronous motor comprising, a stator, a rotor mounted for rotation within said stator, and having a rotor winding, said stator having three phase windings, each phase winding having a separate first part and a second part with said first and second parts being in phase wih one another, the first part of each phase winding being connected in a first wye arrangement, the second part of each phase winding being connected in a second wye arrangement, and terminal means for connecting said first wye arrangement and said second wye arrangement to separate sources of power whereby said motor can operate at reduced power using only one of said first and second wye arrangements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000601476A CA1299641C (en) | 1989-06-01 | 1989-06-01 | Cycloconverter drive utilizing a dual stator motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000601476A CA1299641C (en) | 1989-06-01 | 1989-06-01 | Cycloconverter drive utilizing a dual stator motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1299641C true CA1299641C (en) | 1992-04-28 |
Family
ID=4140143
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000601476A Expired - Fee Related CA1299641C (en) | 1989-06-01 | 1989-06-01 | Cycloconverter drive utilizing a dual stator motor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1299641C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105515248A (en) * | 2015-09-30 | 2016-04-20 | 常州倍安特动力机械有限公司 | Power generation device with adjustable output voltage |
-
1989
- 1989-06-01 CA CA000601476A patent/CA1299641C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105515248A (en) * | 2015-09-30 | 2016-04-20 | 常州倍安特动力机械有限公司 | Power generation device with adjustable output voltage |
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