An Inductance Identification Method for Robust Position Sensorless Control to Magnetic Saturation of IPMSMs

Abstract

A position sensorless control method for interior permanent magnet synchronous motors (IPMSMs) has been developed to reduce cost and improve reliability. The performance of position estimation largely depends on the motor parameters. Inductance varies due to magnetic saturation during operation. Therefore, model-based position estimation deteriorates if the inductance variation is not taken into account. Traditional position estimation methods use an ideal IPMSM model that assumes the d-axis and q-axis are completely magnetically decoupled, that is, only the d-axis and q-axis self-inductances are considered. However, in reality, a cross-coupling effect exists in actual IPMSMs, resulting in mutual inductance between the d-axis and q-axis. This mutual inductance also degrades position estimation performance, particularly under heavy load conditions. Thus, it is important to identify the inductance while considering both magnetic saturation during operation and cross-coupling, in order to achieve accurate position estimation. In this paper, we propose a novel flux observer that accounts for the cross-coupling inductance and present an adaptive approach. Using the adaptive scheme, time-varying parameter identification can be effectively addressed. The effectiveness of the proposed method is verified through experimental results.