Investigation of saturation impact on an IPMSM saliency-based sensorless control for automotive applications

The paper deals with the sensorless control of salient-pole Interior-Permanent-Magnet-Synchronous-Machines (IPMSMs) adressed to electric vehicle applications, using a high frequency voltage injection technique. This technique is effective at zero and low motor speed, and takes advantage of the peculiarity of the rotor geometry. Indeed, the expected estimation performances heavily depend on the rotor saliency, so, on the geometry of the IPMSM rotor. The main focus of this work is first to experiment the magnetic saturation effect on the machine saliency for different operating conditions and consequently identify the feasible sensorless control region when taking into account the chosen current control strategy. Then, it is intended to evaluate the impact of saturation induced cross-coupling terms on the position estimation accuracy. This analysis is supported by experimental evidence obtained using a salient-pole interior PM synchronous machine, however, the findings may also be applicable to other AC salient machines.