A novel proportional-integral (PI) stator resistance estimator for a direct torque controlled interior permanent magnet synchronous machine drive

The stator resistance variation will deteriorate the performance of a direct torque controlled (DTC) drive, therefore it is a big issue of DTC. In order to solve this issue, a novel stator resistance estimator for an interior permanent magnet synchronous machine (IPMSM) DTC drive based on stator current has been proposed and evaluated. By means of comparing the actual current and the reference current, the change of stator resistance can be tracked and compensated. The advantage of this scheme is that it is based on the mathematical model of the IPMSM and needs the current signal and reference flux linkage and torque only. Furthermore, the instability caused by the over estimation of the stator resistance is also examined. The physical explanation of this phenomenon is also given. Modeling and experimental results show the effectiveness of the new method.