Method and apparatus for controlling operation of a rotary electric machine

A method for controlling a multi-phase rotary electric machine coupled to an actuator, the method comprising:

• determining a torque command and a rotational speed of the electric machine;
• determining an electrical time constant associated with the electric machine;
• determining a peak torque per loss parameter for the electric machine at the rotational speed of the electric machine;
• determining a second torque parameter for the electric machine at the rotational speed of the electric machine;
• determining a control period based upon the electrical time constant for the electric machine;
• determining a first subperiod for controlling the electric machine at the peak torque per loss parameter and a second subperiod for controlling the electric machine at the second torque parameter, wherein the control period is equivalent to a sum of the first and second subperiods, and wherein an average torque generated by the electric machine over the control period is equivalent to the torque command;
• and
• controlling the electric machine to generate torque transferable to the actuator responsive to the peak torque per loss parameter for the first subperiod and controlling the electric machine to generate torque transferable to the actuator responsive to the second torque parameter for the second subperiod during the control period.

A control system for a multi-phase rotary electric machine, comprising:

• an inverter, electrically connected to the electric machine;
• and
• a controller, operatively coupled to the inverter and in communication with sensors that are disposed to monitor the electric machine, the controller including an instruction set, the instruction set executable to:
• determine a torque command and a rotational speed of the electric machine;
• determine a peak torque per loss parameter for the electric machine based upon the rotational speed of the electric machine;
• determine a second torque parameter for the electric machine associated with a minimum power loss at the rotational speed of the electric machine;
• determine a modulated torque command for controlling the electric machine based upon the peak torque per loss parameter and the second torque parameter, wherein the modulated torque command includes an arbitrarily-generated torque profile that is determined based upon the torque command and minimizes system losses based upon the peak torque per loss parameter and the second torque parameter;
• and
• control the inverter to operate the electric machine based upon the modulated torque command and the torque profile.