An Improved Sliding Mode Observer of Sensorless SPMSM Control with Complex Feedback Vector

摘要

In this paper, an improved sliding mode observer (SMO) based on complex feedback coefficient is proposed for surface-mounted permanent magnet synchronous machine (SPMSM) sensorless control. SMO has been widely used in sensorless control to estimate the rotor position. The conventional SMO replaces the discontinues sign function with the liner feedback function in the boundary layer so as to reduce the chattering problem. However, there exists estimated error of rotor position in the boundary layer in this way. Differing from the conventional method that the back electromotive force (EMF) is estimated to track the real one as well as possible in each axis separately, the proposed SMO combines the observation current error of α-axis and β-axis errors by using complex feedback coefficient to estimate the back EMF. In this situation, the estimated back EMF coincides the real one in phase regardless of amplitude. Therefore, the proposed SMO can eliminate the estimated error of rotor position. Physical experimental results are presented to verify the validity of the method.