Electric motor stator winding temperature estimation

A method for controlling a torque command in a vector controlled motor drive system, the method comprising the steps of:

• determining whether a motor speed is greater than a speed threshold;
• estimating, when the motor speed is greater than the speed threshold, a stator winding temperature for each of a plurality stator windings based on a total power loss, wherein the total power loss comprises stator winding power loss and a core power loss;
• and
• derating the torque command in response to the estimated stator winding temperature of one or more of the stator windings.

A method comprising:

• determining a stator winding resistance for each stator winding of a motor based on a temperature of that stator winding and a temperature coefficient of resistance of that stator winding;
• determining a stator winding power loss for each phase based on the stator winding resistance for that stator winding;
• determining total power loss in each phase based on said stator winding power loss for each phase and a core power loss;
• determining a phase temperature change for each phase based on said total power loss, motor speed, and a combined thermal impedance model for that phase;
• and
• estimating a stator winding temperature for each of the stator windings based on said phase temperature change for that phase and a motor coolant temperature.