Fault-tolerant electric motor control system

• US 20050073273A1
• Filed: 10/06/2003
• Published: 04/07/2005
• Est. Priority Date: 10/06/2003
• Status: Active Grant

• Current Assignee: BluWav Systems LLC (Magna International Incorporated)
• Original Assignee: WaveCrest Laboratories LLC (Magna International Incorporated)
• Inventors: Yuan, Guohui, Maslov, Boris A.
• Granted Patent: US 6,949,908 B2
• Time in Patent Office: Days
• US Class Current: 318/437
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36
• CPC Class Codes: H02P 6/12 Monitoring commutation; Providing indication of commutation failure
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence

Abstract

The present invention offers a novel control system for a multiphase motor. The control system involves energization circuitry for energizing each phase winding, and a control circuit for defining phase currents for individual phases of the motor to generate control signals applied to the energization circuitry for energization of the phase windings. When at least one phase of the motor fails, a mode selection circuit enables the control circuit to operate either in a non-correction mode or in a fault-correction mode. In the non-correction mode of operation, phase currents for phases that remain operational are maintained unmodified. In the fault-correction mode, the phase currents for the remaining phases are modified in accordance with pre-set parameters.

Claims

1. A control system for a multiphase motor having a plurality of stator phase components and a rotor, each stator phase component comprising a phase winding formed on a core element, said system comprising:

energization circuitry connected to the stator phase windings for energizing each phase winding;

a control circuit for defining phase currents for individual phases of the motor to generate control signals applied to said energization circuitry for energization of said phase windings; and

a mode selection circuit for enabling said control circuit to operate in one of first and second modes of operation when a phase of the motor fails,

in the first mode of operation, phase currents for phases that remain operational being maintained unmodified, and

in the second mode of operation, the phase currents for the phases that remain operational being modified in accordance with pre-set parameters.

2. The system of claim 1, wherein in the first mode, the control circuit is configured to disable energization of a phase winding corresponding to a failed phase.

3. The system of claim 1, wherein in the second mode, the control circuit is configured to modify phase current for a remaining phase in accordance with a distance between the remaining phase and a failed phase.

4. The system of claim 1, wherein in the second mode, the control circuit is configured to modify phase current for a remaining phase in accordance with a pre-set maximum current magnitude at a phase location arranged at a predetermined phase angle with respect to a failed phase.

5. The system of claim 1, wherein in the second mode, the control circuit is configured to modify phase current for a remaining phase in accordance with a pre-set minimum current magnitude at a phase angle shifted by 90 degrees with respect to the phase location of the maximum current magnitude.

6. The system of claim 1, wherein the pre-set parameters for phase current modification are customized in accordance with user'"'"'s preferences.

7. The system of claim 6, wherein the pre-set parameters are customized to achieve a desired balance between total torque and torque ripple.

8. A control system for a multiphase motor having a plurality of stator phase components and a rotor, each stator phase component comprising a phase winding formed on a core element, said system comprising:

energization circuitry connected to the stator phase windings for energizing each phase winding;

a control circuit for defining phase currents for individual phases of the motor to generate control signals applied to said energization circuitry for energization of said phase windings; and

a fault correction circuit responsive to a failure of a phase of the motor for enabling the control circuit to modify phase currents for remaining phases in accordance with pre-set parameters.

9. The system of claim 8, wherein the control circuit is configured to modify phase current for a remaining phase in accordance with a phase angle distance between the remaining phase and a failed phase.

10. The system of claim 8, wherein the control circuit is configured to modify phase current for a remaining phase in accordance with a pre-set maximum current magnitude at a phase location arranged at a predetermined phase angle with respect to a failed phase.

11. The system of claim 8, wherein the control circuit is configured to modify phase current for a remaining phase in accordance with a pre-set minimum current magnitude at a phase angle shifted by 90 degrees with respect to the phase location of the maximum current magnitude.

12. The system of claim 8, wherein the pre-set parameters for phase current modification are customized in accordance with user'"'"'s preferences.

13. The system of claim 12, wherein the pre-set parameters are customized to achieve a desired balance between total torque and torque ripple.

14. A method of controlling a multiphase motor comprising the steps of:

selecting between a first and a second mode of operation if a phase of the motor fails,

in the first mode of operation, maintaining unmodified phase currents for phases that remain operational, and

in the second mode of operation, modifying phase currents for the phases that remain operational in accordance with pre-set parameters.

15. The method of claim 14 further comprising the step of disabling energization of a phase winding corresponding to a failed phase in the first mode of operation.

16. A method of controlling a multiphase motor comprising the steps of:

detecting a phase failure, and

modifying phase currents for phases that remain operational in accordance with pre-set parameters.

17. The method of claim 16, wherein phase current for a remaining phase is modified in accordance with a phase angle distance between the remaining phase and a failed phase.

18. The method of claim 16, wherein phase current for a remaining phase is modified in accordance with a pre-set maximum current magnitude at a phase location arranged at a predetermined phase angle with respect to a failed phase.

19. The method of claim 16, wherein phase current for a remaining phase is modified in accordance with a pre-set minimum current magnitude at a phase angle shifted by 90 degrees with respect to the phase location of the maximum current magnitude.

20. The method of claim 16, wherein the pre-set parameters for phase current modification are customized in accordance with user'"'"'s preferences.

21. The method of claim 20, wherein the pre-set parameters are customized to achieve a desired balance between total torque and torque ripple.