Sinusoidal stimulus response for input power health diagnostic

1. A method for diagnosing an input power supply providing power to a motor, the method comprising:

generating a sinusoidal stimulus signal;

applying, using the input power supply, the sinusoidal stimulus signal to the motor;

measuring a response to the sinusoidal stimulus signal;

calculating, based on the response to the sinusoidal stimulus signal, a metric indicative of a status of the input power supply;

determining a degraded condition of the input power supply based on the response to the sinusoidal stimulus signal; and

performing an action in response to determining the degraded condition of the input power supply.

2. The method of claim 1 , wherein the sinusoidal stimulus signal is a non-torque producing voltage that causes the motor to produce zero net torque.

3. The method of claim 1 , wherein applying the sinusoidal stimulus signal to the motor includes switching, by an inverter, a DC power having a bridge voltage, and wherein the response to the sinusoidal stimulus signal includes a sinusoidal voltage component of the bridge voltage.

4. The method of claim 3 , wherein the sinusoidal stimulus signal has a stimulus frequency and the sinusoidal voltage component of the bridge voltage has a response frequency equal to twice the stimulus frequency.

5. The method of claim 1 , wherein generating the sinusoidal stimulus signal includes generating a discretized sinusoidal stimulus signal approximating a sinusoid.

6. The method of claim 5 , wherein generating the discretized sinusoidal stimulus signal includes generating a discretized periodic ramp signal, and determining the discretized sinusoidal stimulus signal based on the discretized periodic ramp signal.

7. The method of claim 5 , wherein generating the discretized sinusoidal stimulus signal includes determining a value using a term to compensate for jitter introduced by an inconsistency in timing to perform at least one calculation.

8. The method of claim 1 , wherein determining the degraded condition of the input power supply includes estimating a harness resistance value using a statistical model.

9. The method of claim 8 , wherein estimating the harness resistance value using the statistical model includes computing a harness resistance estimate based on a magnitude of the response to the sinusoidal stimulus signal and an average of the response to the sinusoidal stimulus signal.

10. A method for diagnosing an input power supply providing power to a motor, the method comprising:

generating a stimulus signal having a stimulus magnitude;

applying, using the input power supply, the stimulus signal to the motor;

measuring a response to the stimulus signal;

determining a degraded condition of the input power supply based on the response to the stimulus signal; and

performing an action in response to determining a degraded condition of the input power supply,

wherein the degraded condition of the input power supply includes a harness resistance value, and

wherein generating the stimulus signal includes determining the stimulus magnitude based on an estimate of the harness resistance value.

11. The method of claim 10 , wherein the stimulus signal includes a sinusoidal stimulus signal.

12. The method of claim 10 , wherein determining the stimulus magnitude based on the estimate of the harness resistance value includes determining a maximum stimulus magnitude to maintain a bridge voltage of the input power supply above a predetermined value.

13. The method of claim 10 , wherein determining the stimulus magnitude based on the estimate of the harness resistance value further includes determining a maximum stimulus magnitude based on an approximation of a battery voltage of the input power supply.

14. A system for diagnosing an input power supply providing power to a motor, the system comprising:

a processor and a memory including instructions that, when executed by the processor, cause the processor to:

generate a sinusoidal stimulus signal;

apply, using the input power supply, the sinusoidal stimulus signal to the motor;

measure a response to the sinusoidal stimulus signal;

determine a degraded condition of the input power supply based on the response to the sinusoidal stimulus signal; and

perform an action in response to determining the degraded condition of the input power supply.

15. The system of claim 14 , wherein the sinusoidal stimulus signal is a non-torque producing voltage that causes the motor to produce zero net torque.

16. The system of claim 14 , wherein applying the sinusoidal stimulus signal to the motor includes the instructions causing the processor to cause an inverter to switch a DC power having a bridge voltage, and wherein the response to the sinusoidal stimulus signal includes a sinusoidal voltage component of the bridge voltage.

17. The system of claim 16 , wherein the sinusoidal stimulus signal has a stimulus frequency and the sinusoidal voltage component of the bridge voltage has a response frequency equal to twice the stimulus frequency.

18. The system of claim 14 , wherein generating the sinusoidal stimulus signal includes generating a discretized sinusoidal stimulus signal approximating a sinusoid.

19. The system of claim 18 , wherein generating the discretized sinusoidal stimulus signal includes generating a discretized periodic ramp signal, and determining the discretized sinusoidal stimulus signal based on the discretized periodic ramp signal.

20. The system of claim 18 , wherein generating the discretized sinusoidal stimulus signal includes determining a value using a term to compensate for jitter introduced by an inconsistency in timing of calculations.