Real Time Estimator of Winding Hotspot Temperature for PMSM Drives

The electrical drives for high-performance applications often present a relevant temperature gradient within the stator winding. If a thermistor is often embedded in the machine, the hottest winding point is normally not accessible, leading to the need for high thermal safety margins, and so arming the full exploitation of the machine's torque capability. To solve this issue, the present work deals with hotspot temperature monitoring and prediction for synchronous motor drives. An advanced Lumped Parameter Thermal network is proposed, modeling the thermal gradient inside the stator. An automatic calibration procedure is presented, based on simple thermal commissioning tests. Experimental results on a high-performance traction PMSM demonstrate the effective capability of dynamically tracking the hotspot temperature, with a residual error <5°C, thus enabling the full and safe exploitation of the motor overload capabilities.