Caterpillar Inc.
Torque control based on rotor resistance modeling in induction motors

Abstract:

A control system for an induction motor executes an on-board, dynamic model to estimate rotor resistance and control the torque output by the induction motor. The model includes equations to calculate stator and rotor temperatures and/or resistances based on combinations of voltage and current data, electrical frequency, rotor speed, switching patterns, and air flow rates during operation of the induction motor. The control system updates the model based on feedback collected during the operation of the induction motor, including the difference between the actual observed stator temperature and the stator temperature predicted by the model. The model is updated to converge the predicted stator temperature on the actual observed stator temperature, and corresponding updates are made to the rotor resistance estimations to provide more accurate estimations of the rotor resistance and improve the accuracy of the induction motor torque output.