Compensation of cross-saturation effects on IPMSM sensorless control - application to electric vehicle

Most of automotive applications rely on Permanent Magnet Synchronous Machines (PMSMs) thanks to the afforded high efficiency and reduced cost and size. However, this trend is subject to severe safety requirements, particulary related to the reliability of the mechanical position sensor. In this context, the present paper deals with PMSM sensorless control, aimed at providing the position information redundancy. Yet, some side effects, as saturation and cross-coupling, may compromise the estimation quality. To achieve a deeper insight into the impact of these phenomena, authors highlight the way that sensorless estimation accuracy is predicted from the rotor geometry anisotropy. The objective is two-fold: 1) Provide a detailed approach for the characterization of the PMSM magnetic model under different load conditions, 2) Deduce the machine saliency behaviour and the induced estimation error due to saturation effects. To do so, an accurate flux linkage model is required. This model should allow to evaluate the arising cross-saturation terms. Experimental results are presented, referring to two test traction motors dedicated to the electric vehicle application.