Design of Wireless Temperature Monitoring System for Measurement of Magnet Temperature of IPMSM

Residual flux density of permanent magnet is significantly influenced by its own temperature. In case of Interior Permanent Magnet Synchronous Machine (IPMSM), which is widely used as a traction motor of EV/HEV, its torque capability is directly affected by the temperature of the permanent magnet. Also, the irreversible demagnetization of the magnet, which is a major concern of automotive industry, is deeply related to the temperature of the magnet of the motor. Therefore, the issue of the identification of the temperature of the magnet on line is getting wide attention from automotive industry. The temperature can be estimated based on thermal model or terminal characteristics of IPMSM, which may be linked to the temperature of the magnet. To analyze variation of characteristics of IPMSM according to the magnet temperature, accurate measurement of the temperature of permanent magnet is crucial. In this paper a system to measure the temperature of magnet of IPMSM is designed and tested. Since the invasion of the measurement system before and after the installation of sensors is minimized, the variation of the basic characteristics of IPMSM such Back-EMF and flux distribution due to the measurement system are not noticeable. In addition, the measured temperature can be easily monitored through wireless communication channel. The accuracy, effectiveness, and robustness to EMI of inverter driving IPMSM have been verified by experimental test.