Method and apparatus for controlling an electric motor

A control system for controlling the output power of a permanent magnet electric motor, the control system including:

• (b) a limiter means for:
• i. setting a limit value of output power;
• ii. detecting a speed value of the electric motor;
• and
• iii. processing said detected value of speed and said limit value of output power so as to provide a target torque value signal;
• and
• (b.) a control means for processing said target torque value signal so as to provide a control signal for adjusting an electric current supplied to the electric motor to thereby vary the output torque of the electric motor toward the target torque value.

A programmed computer for controlling the output power of a permanent magnet electric motor for an electric traction system for a vehicle, the programmed computer including:

• (c.) a processing means;
• (d.) a memory for storing executable instructions, said executable instructions being executable by the processing means to make the processing means:
• i. set a limit value of output power for the motor;
• ii. detect a speed value of the electric motor;
• iii. process said detected speed value and said limit value of output power so as to provide a target torque value;
• and
• iv. process said target torque value so as to provide a control signal for adjusting an electric current supplied to the electric motor so as to vary the output torque of the electric motor toward the target torque value.