A stator resistance compensator for a direct torque controlled low speed and high torque permanent magnet synchronous motor

Nowadays, the research on low speed and high torque permanent magnetic synchronous machine more and more attention in the fields of motors, and has great science significance and application value. Direct torque control (DTC) has become an a accepted advanced control method beside the current vector control Although DTC was initially applied in asynchronous machines, but it has been introduced successfully to synchronous machines. This paper will discuss the DTC in the PMSM. With DTC, the electromagnetic torque and stator flux can be estimated using the measured stator voltages and currents. The estimation does depend on motor parameters except for the stator resistance. The variation of stator resistance due to changes in temperature or frequency degrades 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 becomes necessary. Estimation of the stator resistance and its compensation using a PI-fuzzy estimation has been proposed in this paper.