Motor controller having low noise high frequency signal injection

1. A method, comprising:

receiving a first injection signal having first signal characteristics;

receiving a second injection signal having second signal characteristics that are different than the first signal characteristics;

selecting a first one of the first and second injection signals for combining with a direct voltage signal to provide an input to a first transform, wherein the first and second signal characteristics are configured to reduce acoustic noise generated by an electric motor, wherein the direct voltage signal is defined in a (d,q) coordinate system with orthogonal components along d (direct) and q (quadrature) axes such that a field flux linkage component of motor current is aligned along the d axis and a torque component of current is aligned along the q axis; and

converting an output of the first transform to signals for driving the electric motor.

2. The method according to claim 1 , further including high pass filtering a current from the motor.

3. The method according to claim 2 , further including using a second transform on the current from the motor after the high pass filtering.

4. The method according to claim 3 , further including extracting envelope information of high frequency current signal output from the second transform.

5. The method according to claim 4 , further including determining a position error from the extracted envelope information.

6. The method according to claim 5 , wherein the position error is a difference between an injection estimation angle and a real angle for the motor.

7. The method according to claim 6 , further including obtaining an estimation angle for the motor.

8. The method according to claim 1 , further including using a random signal generator for selecting the first one of the selecting a first one of the first and second injection signals.

9. The method according to claim 1 , wherein the first signal characteristics including varying amplitude and frequency.

10. The method according to claim 9 , wherein the first and second injection signals are injected randomly into the first transform.

11. The method according to claim 1 , further including using direct voltage control to provide a quadrature voltage Vq to the first transform.

12. A motor controller, comprising:

a signal generator to generate a first injection signal having first signal characteristics and a second injection signal having second signal characteristics that are different than the first signal characteristics;

an injection controller to select a first one of the first and second injection signals for combining with a direct voltage signal to provide an input to a first transform, wherein the first and second signal characteristics are configured to reduce acoustic noise generated by an electric motor, wherein the direct voltage signal is defined in a (d,q) coordinate system with orthogonal components along d (direct) and q (quadrature) axes such that a field flux linkage component of motor current is aligned along the d axis and a torque component of current is aligned along the q axis; and

a circuit module to converting an output of the first transform to signals for driving the electric motor.

13. The motor controller according to claim 12 , further including a high pass filter to filter a current from the motor.

14. The motor controller according to claim 13 , further including a second transform to transform the current from the motor after the high pass filtering.

15. The motor controller according to claim 14 , an envelope extraction module to extract envelope information of high frequency current signal output from the second transform.

16. The motor controller according to claim 15 , further including an angle processing module to determining a position error from the extracted envelope information.

17. The motor controller according to claim 16 , wherein the position error is a difference between an injection estimation angle and a real angle for the motor.

18. The motor controller according to claim 17 , further including a module to obtain an estimation angle for the motor.

19. The motor controller according to claim 12 , further including a random signal generator for selecting the first one of the selecting a first one of the first and second injection signals.

20. The motor controller according to claim 12 , wherein the first signal characteristics including varying amplitude and frequency.

21. The motor controller according to claim 20 , wherein the first and second injection signals are configured to be injected randomly into the first transform.

22. The motor controller according to claim 12 , further including an input to receive a signal for direct voltage control to provide a quadrature voltage Vq to the first transform.

23. A motor controller, comprising:

a signal generator means for generating a first injection signal having first signal characteristics and a second injection signal having second signal characteristics that are different than the first signal characteristics;

an injection controller means for selecting a first one of the first and second injection signals for combining with a direct voltage signal to provide an input to a first transform, wherein the first and second signal characteristics are configured to reduce acoustic noise generated by an electric motor, wherein the direct voltage signal is defined in a (d,q) coordinate system with orthogonal components along d (direct) and q (quadrature) axes such that a field flux linkage component of motor current is aligned along the d axis and a torque component of current is aligned along the q axis; and

a circuit module to converting an output of the first transform to signals for driving the electric motor.