Magnet Temperature Estimation of IPMSM by Using Reactive Energy

In this paper, a method to estimate the temperature of NdFeB magnet of an Interior Permanent Magnet Synchronous Motor (IPMSM) is derived in medium and high speed operating condition, where the back EMF of the motor is high enough. To estimate the temperature of the magnet, a concept of reactive energy is newly brought out. By using this concept, no temperature sensors are required in neither rotor side nor stator side. Hence, the method is truly noninvasive. Furthermore, as the reactive energy itself is utilized to estimate the temperature, the sensitivity to the variation of the magnet temperature is enhanced compared to the conventional method. The proposed method has been verified in the small-scale experiment set. The performance of the method has been evaluated at various operating conditions of IPMSM.