A PI stator resistance compensator for a direct torque controlled interior permanent magnet synchronous motor drive

The Direct Torque Control (DTC) scheme based on stator flux estimation has gained popularity in recent years since speed feedback is not essential in this technique. With DTC, the electromagnetic torque and stator flux can be estimated using the measured stator voltages and currents. The estimation does not depend on motor parameters except for the stator resistance. The variation of stator resistance due to changes in temperature or frequency degrade the performance of DTC controller by introducing errors in the estimated flux linkage vector and the electromagnetic torque. Compensation for the effect of stator resistance variation then become necessary. Estimation of the stator resistance and its compensation using a proportional-integral (Pr) estimator has been proposed in this paper.