Non-Invasive Magnet Temperature Estimation of IPMSM Based on High-Frequency Inductance With a Pulsating High-Frequency Voltage Signal Injection

In this paper, a method to estimate the temperature of a permanent magnet of a traction motor for automotive applications is derived by analyzing the high-frequency inductance of an interior permanent-magnet synchronous motor. The derived method exploits the high-frequency inductance as an indicator of the magnet temperature, and it does not require a temperature sensor not only on the rotor side but also on the stator side. Hence, the method is truly noninvasive. The proposed method has been verified in a small-scale experimental setup. The performance of the method has been evaluated at various torques, speeds, and magnet temperatures ranging from -24 to 82 °C. Through testing at various operating conditions, it has been confirmed that the maximum error is less than 2.9 °C even when the speed and torque vary.