An extended Kalman filtering approach for estimation of winding temperature in switched reluctance motors

Switched Reluctance Motors (SRMs) have absorbed a great deal of attention in various industrial applications such as Electric Vehicles (EVs) due to their robust and fault tolerant structure. However, thermal protection of the SRM windings in case of overload conditions or abnormal cooling situations is essential to prevent the reduction of the winding insulation lifetime. This paper presents a model-based technique to estimate the phase winding temperature in the SRMs. The winding resistance is an outstanding indicator of the winding temperature due to the linear relationship between these two quantities. As a result, the proposed technique applies an Extended Kalman Filter (EKF) to estimate the phase winding resistance and as well as the winding temperature. The detailed theoretical formulations and analysis are presented. Furthermore, the effectiveness of the proposed approach is verified using simulations for a three phase, 6/4 SRM. The results confirm the capability of this technique for estimating the phase winding temperature during different operating conditions including variations in the load power and speed in the SRM.