Real-Time Maximum Magnet Temperature Prediction for Surface-Mounted PMSMs

This article proposes a novel approach to predict the maximum permanent magnet (PM) temperature for surface-mounted PM synchronous machines (SPMSMs). Using the 3-D conduction heat transfer equation, a generic correlation between average and maximum PM temperatures is analytically derived for the first time. It depends on the basic geometric/thermal parameters, the PM eddy current loss, and the stator thermal behavior. Using the average PM temperature obtained by the rotor flux linkage estimation method, the PM loss calculated by the finite element analysis (FEA), and a thermal sensor installed on the stator, the maximum PM temperature can be determined semi-analytically. The contribution of the PM temperature rises caused by the stator thermal state and the rotor PM loss can also be evaluated separately. The proposed method exhibits similar estimation accuracy as the FEA while requiring significantly less computation time. The effectiveness of the proposed method is validated experimentally based on a 12-slot/10-pole SPMSM.