Driving system for reluctance type motor

• US 5,319,297 A
• Filed: 04/28/1992
• Issued: 06/07/1994
• Est. Priority Date: 08/28/1990
• Status: Expired due to Term

• Current Assignee: Lloyd & Associates
• Original Assignee: Kabushikigaisya Sekogiken
• Inventors: Bahn, Itsuki
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Cabeca, John W.
• Application Number:
  US07/849,396
• Time in Patent Office: 770 Days
• Field of Search: 318/701, 318/254, 318/439, 318/696
• US Class Current: 318/701
• CPC Class Codes: H02P 25/098 Arrangements for reducing torque ripple

Abstract

This driving system can reduce ripple components included in the output torque of reluctance type motors. During a driving operation of a motor (3), a data selecting readout unit (51) decodes an output of an A/D converter (18a) which corresponds to a command exciting current value fed from a supply current control circuit, and selects one of memories (51a to 51e) corresponding to the command exciting current value. Further the torque ripple data from the selected memory is successively read out in accordance with an address output of an address counter (57) that is renewed every time a shaft encoder (6) sends out an output and, in turn, supplies it through a D/A converter (59) to the current supply control circuit (61). The current supply control circuit corrects the command exciting current based on the torque ripple data, and controls actuation of the motor by the corrected command exciting current to remove the torque ripple in the motor output torque.

Claims

1. A driving system for controlling actuation of a reluctance type motor with a rotor and an armature having exciting coils, comprising:

a position detecting device, operatively connected to the rotor, for generating a position detecting signal representing an actual rotational position of the rotor;

a division circuit for receiving torque data from the reluctance type motor and a voltage proportional to a command exciting current, dividing the torque data by the voltage proportional to the command exciting current and outputting torque ripple data;

a memory device pre-memorizing the torque ripple data as a function of the command exciting current and a rotor rotational position; and

a current supply control circuit, operatively connected to the exciting coils, said position detecting device and said memory device, for supplying to each one of the exciting coils an exciting current corresponding to a corrected command exciting current corrected by the torque ripple data read out from said memory device on the basis of the position detecting signal and the command exciting current, said current supply control circuit including;

a multiplication circuit, receiving the torque ripple data and the command exciting current, multiplying the torque ripple data with the command exciting current and outputting a corrected command exciting current.

2. A driving system in accordance with claim 1, wherein said position detecting device performs position detection in a predetermined rotational section of the rotor to generate pulse signals including a n origin pulse signal, and further comprising data readout means for reading out the torque ripple data from said memory device in response to the pulse signal.

3. A driving system in accordance with claim 1, wherein said current supply control circuit performs chopper control to change the exciting current flowing through the exciting coils to be a value corresponding to the corrected command exciting current.

4. A driving system in accordance with claim 2, wherein said predetermined rotational section of the rotor corresponds to one complete revolution of the rotor.

5. A driving system in accordance with claim 2, wherein said predetermined rotational section of the rotor corresponds to one cycle of periodic changes of the output torque of the motor.

6. A driving system in accordance with claim 1, wherein said memory device stores torque ripple data produced, based on actual output values of the motor, at a plurality of rotor rotational positions belonging to a predetermined rotational section of the rotor which are successively measured during a driving operation of the reluctance type motor controlled in response to each of a plurality of command exciting current values.

7. A driving system in accordance with claim 6, wherein said memory device stores torque ripple data proportional to the actual output torque value.

8. A driving system in accordance with claim 6, wherein said memory device stores torque ripple data reversely-proportional to the actual output torque value.

9. A driving system for controlling actuation of a reluctance type motor having a rotor and having an armature having exciting coils, comprising:

a position detecting device generating a position detecting signal representing an actual rotational position of the rotor;

a rotational body disposed synchronously rotatable together with the rotor and having an output peripheral surface comprising a plurality of axial regions each having physical values respectively corresponding to torque ripple data as a function of a corresponding one of a plurality of command exciting current values and a rotor rotational position;

a physical value detector having a detecting portion disposed shiftable along an axial direction of said rotational body so as to be able to face to any one of said plurality of axial regions on the outer peripheral surface of said rotational body;

a servo device for positioning said detecting portion so that said detecting portion faces one of said plurality of axial regions on the outer peripheral surface of said rotational body which corresponds to the command exciting current; and

a current supply control circuit for supplying each exciting coil with an exciting current corresponding to the command exciting current corrected by the torque ripple data corresponding to a physical value detected by said physical value detector in which said detecting portion is thus positioned, said current supply control circuit including;

a multiplication circuit receiving the torque ripple data and the command exciting current and multiplying the torque ripple data with the command exciting current and outputting a corrected command exciting current.

10. A driving system in accordance with claim 9, wherein said rotational body has a radius serving as said physical value which varies in a circumferential direction on the basis of the torque ripple data in said axial region.

11. A driving system in accordance with claim 9, wherein said current supply control circuit performs a chopper control to change exciting current flowing through said exciting coil to be a value corresponding to said corrected command exciting current.

12. A driving system in accordance with claim 9, wherein said supply current circuit restricts current supply to each of said exciting coils to only a central portion of a rotor rotational section at which the motor can generate output torque in response to the current supply to each of said exciting coils.

13. A driving system in accordance with claim 9, wherein said outer peripheral surface of the rotational body comprises a physical value corresponding to torque ripple data produced based on actual output torque values of the motor at a plurality of rotor rotational positions belonging to a predetermined rotational section of the rotor which are successively measured during driving operation of the reluctance type motor controlled in response to each of a plurality of command exciting current values.

14. A driving system in accordance with claim 13, wherein the rotational body is formed to have the outer peripheral surface comprising a physical value corresponding to torque ripple data proportional to said actual output torque value.

15. A driving system in accordance with claim 13, wherein the rotational body is formed to have the outer peripheral surface comprising a physical value corresponding to torque ripple data reverse-proportional to said actual output torque value.