Controller anti-windup for permanent magnet synchronous machines

1. A system for preventing controller windup in a motor control system, the system comprising:

a first anti-windup module that receives a commanded voltage and a limited voltage command, the limited voltage command is applied to an electric motor, the first anti-windup module generates a first modified current command by modifying a current command that is applied to the motor control system, the modification is based on a ratio of the commanded voltage and the limited voltage command; and

a second anti-windup module that receives the commanded voltage and the limited voltage command, the second anti-windup module generates a second modified current command by modifying the first modified current command, the modification based on a difference between the commanded voltage and the limited voltage command, the second modified current command used to generate a torque using the electric motor.

2. The system of claim 1 , further comprising:

a limiting module that determines the limited voltage command in response to the commanded voltage exceeding an available voltage of a motor power source.

3. The system of claim 1 , further comprising:

a current command generator that generates the current command that is input to the motor control system based on a torque command indicative of an amount of torque to be generated using the electric motor.

4. The system of claim 1 , wherein the second anti-windup module uses an integrator back calculation to generate the second modified current command, the integrator back calculation comprising scaling the difference using a gain matrix

G

AW

=

[

G

Add

G

Adq

G

Aqd

G

Aqq

]

,

where G Add , G Adq , G Aqd , and G Aqq are anti-windup parameters.

5. The system of claim 4 , wherein the anti-windup parameters are based on cutoff frequencies for d-axis and q-axis of closed-loop current controller.

6. The system of claim 4 , wherein G Aqd and G Adq are set to zero.

7. The system of claim 1 , wherein the first anti-windup module uses a direct reference calculation to generate the first modified current command.

8. The system of claim 7 , the first anti-windup module further comprising:

a saturation parameter module that determines a saturation parameter based on the limited voltage command, the saturation parameter indicates a magnitude of the commanded voltage exceeding the available voltage;

a non-linear processing module that processes the saturation parameter to generate a processed saturation parameter; and

a reference current modifier module that generates the first modified current command based on the processed saturation parameter.

9. The system of claim 8 , wherein the saturation parameter is an inverse ratio of the commanded voltage to the limited voltage command.

10. The system of claim 1 , wherein the second modified current command retains a proportion of a direct axis (d-axis) current and a quadrature axis (q-axis) current provided by the commanded voltage.

11. The system of claim 1 , wherein the first modified current command comprises a d-axis correction provided by the following equation:

I dT =(1−γ d ) I dmax +γ d I dR

where I dmax is a maximum value of the d-axis current.

12. The system of claim 1 , wherein the first modified current command comprises a q-axis correction provided by the following equation:

I qT =γ q I qR .

13. A method for preventing controller windup in an electric motor, the method comprising:

generating, by a first anti-windup module, a first modified current command by modifying a current command that is applied to a motor control system based on a ratio of a commanded voltage corresponding to the current command and a limited voltage command;

generating, by a second anti-windup module, a second modified current command by modifying the first modified current command based on a difference between the commanded voltage and the limited voltage command; and

using, by a controller, the second modified current command as input to determine a voltage to be applied across the electric motor for torque generation.

14. The method of claim 13 further comprising:

determining the limited voltage command in response to the commanded voltage exceeding an available voltage of a motor power source, the limited voltage command being applied to the electric motor.

15. The method of claim 13 , wherein the second anti-windup module uses an integrator back calculation to generate the second modified current command, the integrator back calculation comprising scaling the difference using a gain matrix

G

AW

=

[

G

Add

G

Adq

G

Aqd

G

Aqq

]

,

where G Add , G Adq , G Aqd , and G Aqq are anti-windup parameters.

16. The method of claim 15 , wherein the anti-windup parameters are based on cutoff frequencies for d-axis and q-axis of closed-loop current controller.

17. The method of claim 13 , generating the first modified current command further comprises:

determining a saturation parameter based on the limited voltage command, the saturation parameter indicates a magnitude of the commanded voltage exceeding the available voltage;

processing the saturation parameter to generate a processed saturation parameter while retaining a nonlinear state; and

generating a modified current command based on the processed saturation parameter, the modified current command is applied to the control system to improve current command tracking.

18. A system for preventing controller windup in a motor control system, the system comprising:

a current command generator that generates a current command that is input to the motor control system based on a torque command indicative of an amount of torque to be generated using an electric motor;

a controller that generates a commanded voltage corresponding to the current command;

a limiting module that determines a limited voltage command in response to the commanded voltage exceeding an available voltage of a motor power source, the limited voltage command being applied to the electric motor; and

an anti-windup module that receives the commanded voltage and the limited voltage command, the anti-windup module generates a modified current command by modifying the current command, the modification based on a difference between the commanded voltage and the limited voltage command, the anti-windup module uses an integrator back calculation to generate the modified current command, the integrator back calculation comprising scaling the difference using a gain matrix

G

AW

=

[

G

Add

G

Adq

G

Aqd

G

Aqq

]

,

where G Add , G Adq , G Aqd , and G Aqq are non-zero anti-windup parameters.

19. The system of claim 18 , wherein the anti-windup parameters are based on cutoff frequencies for d-axis and q-axis of closed-loop current controller.

20. The system of claim 18 , wherein G Aqd and G Adq are set to zero.