Method of controlling an inverter during MOSFET shorts

Patent metadata

Field	Value
Publication number	US-10000233-B2
Application number	US-201715417797-A
Country	US
Kind code	B2
Filing date	Jan 27, 2017
Priority date	Jan 28, 2016
Publication date	Jun 19, 2018
Grant date	Jun 19, 2018

Abstract

Technical solutions are described for mitigating braking torque in a motor of a steering system caused by a FET short. For example, an example mitigation system includes a mitigation module that adjusts a motor torque in response to a FET short. The mitigation system further includes a mitigation-enable module that selectively enables and disables the mitigation module based on a handwheel torque signal. Further, the mitigation system includes a damping module that reduces the motor torque based on a motor velocity signal for the motor.

First claim

What is claimed is:

1. A system for mitigating braking torque in a motor of a steering system, the system comprising:
a mitigation module that adjusts a motor torque in response to a FET short;
a mitigation-enable module that selectively enables and disables the mitigation module based on a handwheel torque signal; and
a damping module that reduces the motor torque based on a motor velocity signal for the motor.

2. The system of claim 1 , wherein the mitigation-enable module enables the mitigation module in response to the handwheel torque signal being above a predetermined threshold.

3. The system of claim 2 , wherein the mitigation-enable module disables the mitigation module in response to the handwheel torque signal being at or below the predetermined threshold.

4. The system of claim 1 , wherein the handwheel torque signal is indicative of input torque to the steering system in response to the FET short.

5. The system of claim 1 , wherein the mitigation module determines a scaling factor for a modulation index used during mitigation of the FET short.

6. The system of claim 1 , wherein the damping module includes a low pass filter that generates filtered motor velocity prior to determining a damping-factor to reduce the motor torque.

7. The system of claim 1 , wherein the damping module is configured to reduce a braking torque component included in the motor torque according to a back electro-magnetic field of the motor.

8. The system of claim 7 , wherein the back electro-magnetic field is proportional to the motor velocity.

9. A method for mitigating braking torque in a motor, the method comprising:
adjusting, by a mitigation module, a motor torque generated by the motor in response to a FET short;
selectively enabling and disabling, by a mitigation-enable module, the mitigation module based on an input torque signal; and
reducing, by a damping module, the motor torque based on a motor velocity signal for the motor.

10. The method of claim 9 , further comprising enabling the mitigation module, by the mitigation-enable module, in response to the input torque signal being above a predetermined threshold.

11. The method of claim 10 , further comprising disabling the mitigation module, by the mitigation-enable module, in response to the input torque signal being at or below the predetermined threshold.

12. The method of claim 9 , wherein the input torque is indicative of a torque generated by the motor in a previous iteration.

13. The method of claim 9 , further comprising determining, by the mitigation module, a scaling factor for a modulation index used during mitigation of the FET short.

14. The method of claim 9 , further comprising filtering, by the damping module, using a low pass filter, the motor velocity prior to determining a damping-factor to reduce the motor torque.

15. The method of claim 9 , further comprising reducing, by the damping module, a braking torque component included in the motor torque according to a back electro-magnetic field of the motor.

16. The method of claim 15 , wherein the back electro-magnetic field is proportional to the motor velocity.

17. A computer program product comprising a non-volatile computer readable storage medium, the computer readable storage medium comprising computer executable instructions, wherein the computer readable storage medium comprises instructions to:
adjust, by a mitigation module, a motor torque generated by the motor in response to a FET short, the motor torque being generated to assist an input torque;
selectively enable and disable the mitigation module based on the input torque; and
reduce the motor torque based on a motor velocity signal for the motor.

18. The computer program product of claim 17 , further comprising instructions to enable the mitigating in response to the input torque being above a predetermined threshold.

19. The computer program product of claim 18 , further comprising instructions to disable the mitigating in response to the input torque being at or below the predetermined threshold.

20. The computer program product of claim 17 , wherein reducing the motor torque comprises: reducing a braking torque component included in the motor torque according to a back electro-magnetic field of the motor, the back electro-magnetic field being proportional to the motor velocity.

Assignees

• Steering Solutions Ip Holding

Inventors

• Skellenger Dennis B
• Chandy Ashok

Classifications

• B62D5/0487

  detecting motor faults (B62D5/0496 takes precedence) · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02P29/027

  the fault being an over-current · CPC title

• B62D5/0463 Primary

  calculating assisting torque from the motor based on driver input · CPC title

• H02P29/028

  the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault · CPC title