Electrically controlled synchronous machine

• US 4,450,396 A
• Filed: 09/23/1980
• Issued: 05/22/1984
• Est. Priority Date: 09/23/1980
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Thornton, Richard D.
• Primary Examiner(s): Rubinson, G. Z.
• Assistant Examiner(s): Moose, Richard M.
• Application Number:
  US06/190,019
• Time in Patent Office: 1,337 Days
• Field of Search: 318/705, 318/710, 318/711, 318/715, 318/716, 318/717, 318/718, 318/720, 318/721, 318/724, 318/798, 318/799, 318/800, 318/254, 318/696
• US Class Current: 318/721
• CPC Class Codes: H02K 29/12 using detecting coils using the machine windings as detecting coil
• CPC Class Codes: H02P 25/03 with brushless excitation
• CPC Class Codes: H02P 25/092 Converters specially adapted for controlling reluctance motors
• CPC Class Codes: H02P 25/0925 wherein the converter comprises only one switch per phase
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

An electronically controlled rotating synchronous machine having armature and field windings on the same magnetically-permeable core. The rotor of the machine is an open tooth structure. The self inductance of the armature and field windings is substantially independent of relative position between the rotor and stator but mutual inductance between the armature and field windings varies with relative position. A rotor position detector senses the voltage in one of the machine windings and relates that voltage to said relative position. Switches are provided to control electric current flow in the armature winding on the basis of the voltage sensed by the detector.

Claims

1. An electronically controlled synchronous machine that comprises:

a magnetically-permeable cylindrical rotor comprising a periodic tooth structure and radial airgap;

a stator having stator windings comprising at least two armature windings and one field winding, the stator windings being situated about the stator such that self inductance in the armature windings and the field winding is substantially independent of rotor position, but the mutual induction between the armature windings and the field winding is variable with relative position between the rotor and the stator whereby continuous torque is produced when appropriately shaped and synchronized current waveforms are introduced into the armature windings; and

rotor position detector means for sensing a voltage in at least one of the stator windings and for relating that voltage to the relative position between the rotor and the stator so as to permit the proper synchronizing of the armature current waveforms with relative position between rotor and stator.

2. An electronically controlled synchronous machine as claimed in claim 1 in which the stator windings further comprise a sensing winding, magnetically coupled to other stator windings and situated about the stator such that a mutual inductance between the sensing winding and the field winding varies with relative positioning of the rotor and the stator, and said rotor position detector means further comprises means for sensing a voltage in said sensing winding.

3. An electronically controlled synchronous machine as claimed in claim 2 having means to insert a voltage pulse on the field winding to induce a voltage pulse on the sensing winding, the polarity of the pulse induced in the sensing winding being used to detect relative rotor position even when the rotor is stationary relative to the stator.

4. An electronically controlled synchronous machine as claimed in claim 3 wherein the rotor position detector means comprises a voltage comparator connected between some of the stator windings and operable to compare voltages between the same with a reference voltage.

5. An electronically controlled synchronous machine as claimed in claim 4 that further comprises switch means comprising semiconductor switches connected to control electric current flow in the armature windings and that further comprises a microprocessor connected to receive signals from the voltage comparator and operable to control the speed and/or the torque of the rotor on the basis of these signals.

6. An electronically controlled synchronous machine as claimed in claim 1 wherein said armature windings receive or generate ac energy and the field winding receives dc energy.

7. An electronically controlled synchronous machine as claimed in claim 3 wherein the stator winding comprises more than two armature windings.

8. An electronically controlled synchronous machine as claimed in claim 3 wherein the position detector means comprises a voltage comparator operable to compare voltages between some of the stator windings.

9. An electronically controlled synchronous machine as claimed in claim 1 wherein the rotor position detector means comprises a voltage comparator connected between some of the stator windings and operable to compare voltages between the same with a reference voltage.

10. An electronically controlled synchronous machine as claimed in claim 6 that further comprises switch means comprising semiconductor switches connected to control electric current flow in the armature windings and that further comprises a microprocessor connected to receive signals from the voltage comparator and operable to control the speed and/or the torque of the rotor on the basis of these signals.

11. An electronically controlled synchronous machine as claimed in claim 1 comprising at least two pairs of armature winding and wherein the magnetic coupling between each pair of armature windings is such that current can be transferred from one winding of the pair to the other.

12. An electronically controlled synchronous machine as claimed in claim 1 having means to insert a voltage pulse on the field winding to induce a voltage pulse in the armature windings, the polarity of the pulse induced in the armature windings being used to detect relative rotor position even when the rotor is at standstill.

13. An electronically controlled machine that comprises:

a stator comprising a stack of steel stator laminations having a cylindrical central opening therethrough and having nonuniformly spaced, alternately adjacently disposed stator teeth and stator slots in the steel laminations adjacent to the cylindrical central opening, said stator including a dc field winding within some of the stator slots and a plurality of ac armature phase windings in some of the stator slots;

a rotor comprising a cylindrical stack of steel rotor laminations having a plurality of substantially uniformly spaced rotor teeth and open rotor slots disposed at the periphery thereof, the diameter of the rotor laminations being slightly smaller than the diameter of the cylindrical central opening in the stator, the rotor being rotatably disposed within said central opening with its axis parallel to the axis of the cylindrical central opening;

the winding being situated about the stator such that self inductance of both said dc field winding and said plurality of ac armature phase windings is essentially independent of rotor angular position as the rotor rotates within said central opening of the stator but mutual inductance between the dc field winding and each ac phase winding varies substantially sinusoidally with rotor angular position in the course of said rotation, there being several electrical cycles for every mechanical cycle in the course of said rotation;

a plurality of power switching circuits connected to control electrical current flow through the ac phase windings of the stator; and

control means connected to control the switching circuits, said control means including sensing means positioned to detect electromagnetically current flow through the ac phase windings to provide a rotor position signal which is analyzed by the control means to indicate the angular position of the rotor, which angular position serves as the basis for sequencing said switching circuits by the control means.

14. An electronically controlled synchronous machine comprising magnetically-permeable toothed laminations stacked to form a first core having a plurality of teeth and slots, an armature winding disposed in some of the slots of the first core, a field winding disposed in some of the slots of the first core, magnetically-permeable toothed laminations stacked to form a second core having a pluraltiy of teeth and slots, the slots of the second core being open slots, the second core being closely spaced with respect to the first core with an airgap therebetween, there being magnetic coupling between the first core and the second core and relative movement therebetween when the machine is operating, the windings being situated about the first core such that the self-inductance of both the armature winding and the field winding is substantially independent of the relative angular position between the first core and the second core but mutual inductances between the armature and field windings vary with the relative positions in a way that continuous force is produced between the first core and the second core when appropriately shaped and synchronized electric current waveforms are present in the armature winding and an electric current is present in the field winding, and position detector means to sense a voltage in at least one of the windings of the first core and operable to relate that voltage to the relative position between first core and the second core to permit the proper synchronizing of the armature current waveforms with the relative position between the first core and the second core.

15. An electronically controlled synchronous machine as claimed in claim 14 comprising two pairs of armature windings, the magnetic coupling between each pair of the armature windings being such that electric current can be transferred from one winding of the pair to the other winding of the pair.

16. An electronically controlled synchronous machine as claimed in claim 15 that includes switch means connected to control electric current flow in the armature windings and in which the position detector means includes a microprocessor connected to receive a signal that is a function of said voltage, which microprocessor is connected to control switching of the switch means and hence electric current flow in the armature windings.

17. An electronically controlled synchronous machine as claimed in claim 16 having a sensing winding, like said armature winding, disposed in some of the slots of the first core and magnetically coupled to the other winding on the first core, said sensing winding having a mutual inductance with respect to the other windings that varies with said relative position, said position detector means sensing a voltage on the sensing winding.

18. An electronically controlled synchronous machine as claimed in claim 14 having means to apply a voltage pulse to one winding in the first core to induce a voltage pulse in the other winding in the first core, which voltage pulse is used to detect the relative position between the first and the second cores.

19. An electronically controlled machine that comprises:

a magnetically-permeable cylindrical rotor comprising a periodic tooth structure and radial airgap;

a stator having stator windings comprising an armature windings and a field structure, the stator windings being situated about the stator such that self-inductance in the armature winding is substantially independent of rotor position, but the mutual induction between the armature winding and the field produced flux of the field structure varies with relative position between the rotor and the stator so that continuous torque is produced when appropriately shaped and current waveforms are present in the armature winding; and

rotor position detector means to sense a voltage in a stator winding and to relate that voltage to the relative position between the rotor and the stator so as to permit the timing armature current waveforms with relative position between rotor and stator.

20. An electronically controlled machine as claimed in claim 19 in which the stator further include a sensing winding, magnetically coupled to the field produced flux and having a mutual inductance therewith which varies with relative positioning of the rotor and the stator, and in which said rotor position detector means is operable to sense a voltage in said sensing winding.

21. An electronically controlled machine as claimed in claim 20 having means to insert a voltage pulse on the field winding to induce a voltage pulse on the field winding to induce a voltage pulse on the sensing winding, the polarity of the pulse induced in the sensing winding being used to detect relative rotor position even when the rotor is stationary relative to the stator.

22. An electronically controlled synchronous machine as claimed in claim 19 in which the field structure comprises permanent magnet means to produce said flux.

23. An electronically controlled synchronous machine as claimed in claim 19 in which the rotor is an open-slot structure.

24. An electronically controlled synchronous machine as claimed in claim 19 comprising electronic drive means that includes switch means connected to control the timing of the armature current waveforms.

25. An electronically controlled synchronous machine as claimed in claim 24 that further includes digital logic means to control said switch means.

26. An electronically controlled synchronous machine as claimed in claim 24 wherein said electronic drive means is unipolar drive means.

27. An electronically controlled synchronous machine as claimed in claim 24 wherein said electronic drive means is bipolar drive means.

28. An electronically controlled synchronous machine as claimed in claim 24 comprising two pairs of armature windings, each pair of the armature windings being magnetically coupled to one another and wherein the electronic drive means in unipolar.