Improving Position Estimation Accuracy of Magnetic Saliency Based Sensorless Control by Considering Cross-Coupling Factor

Abstract

This paper presents a method for improving the position estimation accuracy for magnetic saliency based sensorless control. Conventional magnetic saliency based sensorless position estimation methods are based on the voltage equation of Interior Permanent Magnet Synchronous Motor without incorporation of the mutual inductances between the d-axis and q-axis of rotating reference frame synchronized with rotor. The mutual inductances are caused by magnetic saturation due to load current and high-frequency injection signal for position detection. Furthermore, the mutual inductances contain the harmonic components due to the motor structure. Consequently, the position estimation error is caused by the neglected mutual inductances. It is difficult to determine the actual value of mutual inductance, particularly the harmonic components that vary depending on the rotor position. Therefore, in this paper, a method for improvement of the position estimation accuracy by considering the cross-coupling factor without determining the mutual inductances is proposed. The experimental results demonstrate the validity of the proposed method.