Dynamic stability control for electric motor drives using stator flux oriented control

A method of maintaining torque in an electric vehicle, comprising:

• determining, by a vehicle stability control system comprising one or more processors, for an electric motor of the electric vehicle, a slip frequency indicating a difference between a synchronous speed of a magnetic field of the electric motor and a rotating speed of a rotor of the electric motor;
• comparing, by the vehicle stability control system, the slip frequency with a threshold;
• activating, by the vehicle stability control system, responsive to the slip frequency greater than or equal to the threshold, a slip limiter to adjust a current command to generate an adjusted current command that causes a reduction in the slip frequency;
• and
• deactivating, by the vehicle stability control system, responsive to an external torque command less than a subsequent current command received subsequent to transmission of the adjusted current command, the slip limiter, wherein the external torque command corresponds to pushing an accelerator in the electric vehicle, and the electric motor comprises an induction motor.

A system to maintain torque in an electric vehicle, comprising:

• a vehicle stability control system comprising one or more processors to:
• determine, for an electric motor of the electric vehicle, a stator flux angle in a rotor reference frame of the electric motor;
• compare the stator flux angle with a threshold;
• activate, responsive to the stator flux angle greater than or equal to the threshold, a stator flux angle limiter to adjust a current command to cause a reduction in the stator flux angle;
• and
• deactivate, responsive to an external torque command less than the current command adjusted by the stator flux angle limiter, the stator flux angle limiter, wherein the external torque command corresponds to an indication to accelerate movement of the electric vehicle, and the electric motor comprises a surface permanent magnet motor.