Current sensor fault mitigation for steering systems with permanent magnet DC drives

1. A power steering system comprising:

a motor; and

a motor control system configured to generate an amount of torque using the motor, the amount of torque corresponding to a torque command, the motor control system comprising a processor; and a memory that includes instructions that, when executed by the processor, cause the processor to:

detect a current sensor fault associated with a current sensor used to measure a current across the motor;

determine, in response to the current sensor fault, a base motor velocity estimate based on the torque command, a handwheel torque, and a handwheel position;

determine a compensated motor velocity estimate based on the base motor velocity estimate and an estimated acceleration that corresponds to the base motor velocity estimate; and

generate a current command for generating the amount of torque using the motor, the current command generated using the compensated motor velocity estimate.

2. The power steering system of claim 1 , wherein the instructions, when executed by the processor, further cause the processor to: generate a modified torque command in response to the current sensor fault, a magnitude of the modified torque command changes over a time period.

3. The power steering system of claim 1 , wherein the instructions, when executed by the processor, further cause the processor to: generate a modified voltage command in response to the current sensor fault, a magnitude of the modified voltage command changes over a time period based on a scale factor, the modified voltage command indicating a voltage to be applied across the motor.

4. The power steering system of claim 3 , wherein the modified voltage command is reduced to a magnitude of zero when the current sensor fault is detected and increases from the magnitude of zero over a time period.

5. The power steering system of claim 1 , wherein the instructions, that cause the processor to determine the base motor velocity estimate, cause the processor to: determine the base motor velocity estimate based on a handwheel torque, a handwheel position, and the current command that is generated in response to the torque command.

6. The power steering system of claim 1 , wherein the instructions, that cause the processor to determine the base motor velocity estimate, cause the processor to: determine the base motor velocity estimate based on a handwheel torque, a handwheel position, and a previous modified voltage command.

7. The power steering system of claim 1 , wherein the instructions, when executed by the processor, further cause the processor to generate a second current command that is used to modify a first current command that is computed in response to the torque command.

8. A method for generating an amount of torque using a motor, the amount of torque corresponding to a torque command, the method comprising:

detecting a current sensor fault associated with a current sensor used to measure a current across the brush motor;

determining, in response to the current sensor fault, a base motor velocity estimate based on a handwheel torque, a handwheel position, and a previous modified voltage command;

determining a compensated motor velocity estimate based on the base motor velocity estimate and an estimated acceleration that corresponds to the base motor velocity estimate; and

generating a current command for generating the amount of torque using the motor, the current command generated using the compensated motor velocity estimate.

9. The method of claim 8 , further comprising: generating a modified torque command in response to the current sensor fault, a magnitude of the modified torque command changes over a time period.

10. The method of claim 8 , further comprising:

responsive to detecting the current sensor fault, generating a modified voltage command based at least in part on the compensated motor velocity estimate and the current command, a magnitude of the modified voltage command changes over a time period, the modified voltage command indicating a voltage to be applied across the motor.

11. The method of claim 10 , wherein the modified voltage command is increased from a magnitude of zero when the current sensor fault is detected.

12. A system comprising:

a motor;

a motor control system configured to generate an amount of torque using the motor, the amount of torque corresponding to a torque command, the motor control system comprising a processor; and a memory that includes instructions that, when executed by the processor, cause the processor to:

determine a feedback voltage to be applied across the motor for generating the amount of torque, the feedback voltage determined based on a current across the motor;

detect a current sensor fault associated with a current sensor used to measure a current across the motor;

determine a base motor velocity estimate based on the torque command, a handwheel torque, and a handwheel position;

determine a compensated motor velocity estimate based on the base motor velocity estimate and an estimated acceleration that corresponds to the base motor velocity estimate;

determine an estimated current across the motor based at least in part on the compensated motor velocity estimate; and

determine, using the estimated current, the feedback voltage in response to the current sensor fault.

13. The system of claim 12 , wherein the instructions, when executed by the processor, further cause the processor to: generate a modified torque command in response to the current sensor fault, a magnitude of the modified torque command changes over a time period.

14. The system of claim 12 , wherein the instructions, when executed by the processor, further cause the processor to: generate a modified voltage command based on the feedback voltage, in response to the current sensor fault, a magnitude of the modified voltage command changes over a time period, the modified voltage command indicating the voltage to be applied across the motor.

15. The system of claim 14 , wherein the modified voltage command is reduced to a magnitude of zero when the current sensor fault is detected, the modified voltage command is increased from a magnitude of zero over a time period.

16. The power steering system of claim 1 , wherein the processor, when determining the compensated motor velocity estimate, is to:

determine the compensated motor velocity estimate based on the base motor velocity estimate and the estimated acceleration, such that the compensated motor velocity estimate compensates for a phase lag, wherein the phase lag represents a dynamic time-delay.

17. The method of claim 8 , wherein determining the compensated motor velocity estimate comprises:

determining, based on the base motor velocity estimate and the estimated acceleration, the compensated motor velocity estimate such that the compensated motor velocity estimate compensates for a phase lag, wherein the phase lag represents a dynamic time-delay.

18. The system of claim 12 , wherein the instructions, that cause the processor to determine the compensated motor velocity estimate, cause the processor to:

determine, based on the base motor velocity estimate and the estimated acceleration, the compensated motor velocity estimate such that the compensated motor velocity estimate compensates for a phase lag, wherein the phase lag represents a dynamic time-delay.