Claims

1. A method for controlling an electric motor, the method comprising:receiving a first control command indicative of a desired motor control;determining a current operating condition for the motor;determining whether the first control command meets at least one predetermined criterion at the current operating condition;generating a second control command different from the first control command when the first control command meets the at least one predetermined criterion, generating the second control command including:determining a current value of a parameter of the motor,changing the value of the motor parameter, andusing the changed motor parameter value to generate the second control command; andusing the second control command to control the motor.

2. The method of claim 1, wherein each of the control commands is one of a voltage command or an electrical current command.

3. The method of claim 2, wherein the step of determining whether the first control command meets at least one predetermined criterion at the current operating condition includes determining whether the first control command at the current operating condition is indicative of a flux weakening state for the motor.

4. The method of claim 1, wherein the motor parameter is one of a speed, torque, or power for the motor.

5. The method of claim 1, wherein the motor parameter is speed, the step of generating the second control command including: determining a current speed of the motor, increasing the value of the motor speed, and using the increased value of the motor speed to generate the second control command.

6. The method of claim 1, wherein the desired motor control is one of a desired operating speed, torque, or power for the motor.

7. The method of claim 1, wherein the first control command is a voltage command that includes q and d components, and the step of determining whether the first control command meets at least one predetermined criterion includes determining whether a mathematical combination of the q and d components of the voltage command is greater than a predetermined value.

8. A control system for controlling an electric motor, comprising:a controller configured to:receive a first control command indicative of a desired motor control;determine a current operating condition for the motor;determine whether the first control command meets at least one predetermined criterion at the current operating condition;determine a current value of a parameter of the motor;change the value of the motor parameter when the first control command meets the at least one predetermined criterion;use the changed motor parameter value to generate a second control command different from the first control command; anduse the second control command to control the motor.

9. The control system of claim 8, wherein the motor parameter is one of a speed, torque, or power for the motor.

10. The control system of claim 8, wherein the desired motor control is one of a desired operating speed, torque, or power for the motor.

11. The control system of claim 8, wherein the motor parameter is speed, the value of the motor speed being increased when the first control command meets the at least one predetermined criterion.

12. The control system of claim 8, wherein the first control command is a voltage command that includes q and d components, and the controller determination of whether the first control command meets at least one predetermined criterion includes determining whether a mathematical combination of the q and d components of the voltage command is greater than a predetermined value.

13. The controller of claim 8, wherein each of the current commands is one of a voltage command or an electrical current command.

14. A control system including at least one controller and configured to control an electric motor, the control system comprising:a check module configured to determine if the motor is in a field-weakened state, at a first value of a motor parameter, in response to a first control signal;an adjustment module configured to generate an adjusted motor parameter value if the motor is in the field-weakened state; anda lookup module configured to receive the adjusted motor parameter value and generate a second control signal to control the motor.

15. The control system of claim 14, wherein the adjustment module includes a summation module, the adjustment module being configured to generate the adjusted motor parameter by generating a differential value of the motor parameter and providing the differential value to the summation module, the summation module being configured to receive the first value of the motor parameter and the differential value of the motor parameter, and generate the adjusted motor parameter value.

16. The control system of claim 15, wherein the motor parameter is one of a speed, torque, or power for the motor.

17. The control system of claim 14, wherein the desired motor control is one of a desired operating speed, torque, or power for the motor.

18. The control system of claim 14, wherein the lookup module comprises a lookup table that includes a series of motor parameters and a corresponding series of control signal parameters, and wherein the lookup module is configured to select a control signal parameter from the series of motor parameters based on the received adjusted motor parameter value, and generate the second control signal based on the selected control signal parameter.

19. The control system of claim 14, further comprising a processor, wherein the processor includes the check module, the adjustment module, and the lookup module.