Winding and Magnet Temperature Decoupled Tracking for PMSM Eliminating Saturation Using Small Position Signal Injection and Kalman Filter

This paper proposes a Kalman filter-based stator winding (SW) and permanent magnet (PM) temperature tracking approach for PM synchronous motors (PMSMs), where temperature tracking of SW and PM is decoupled and free from magnetic saturation and thus achieves improved performance. In the proposed approach, a small position signal is added to extract two decoupled temperature-sensitive measurements, a linear state-space model is constructed from the thermal model, and the Kalman filter is employed to accurately track the SW and PM temperatures by using the state-space model and measurements. The small position signal will not affect machine operation, while the temperature tracking can effectively avoid the cross influence between SW and PM. Moreover, there is no need for machine inductances and thus the temperature tracking is not affected by saturation as well as inverter distortion. In the proposed approach, the temperature tracking model includes secant and cosine operations of the current angle, which can effectively improve the signal-to-noise ratio especially under low-load conditions. The effectiveness of the proposed approach is validated on a laboratory test machine with extensive experiments under various load and speed conditions.