Robust Online Stator Resistance Estimation of High- Speed Vector Controlled Induction Motor

A technique for stator-resistance-based thermal monitoring suitable for low-cost vector controlled three phase induction motor (IM) drive is suggested in this paper. Estimated stator resistance can be used for motor thermal protection, or for compensation of parameter variations in control algorithm. The technique is specifically selected to provide robust temperature estimation while rotor is in high speed range. The suggested method is based on periodical injection of relatively small dc voltage offset, which results in technique that is noninvasive but accurate and does not depend on the rest of motor parameters or working conditions. The method is implemented in fixed point microprocessor and tested under various operations conditions. The achieved estimation results at high speeds are superior compared with any model based stator resistance techniques. Keyword: induction motor, stator resistance, parameter estimation