Influence of back-EMF and current harmonics on position estimation accuracy of permanent magnet synchronous machine

The influence of back-EMF and current harmonics on the position estimation accuracy of surface-mounted permanent magnet synchronous machine (SPMSM) based on two sensorless control techniques, i.e. flux-linkage observer (FO) and simplified Extended Kalman Filter (EKF), is investigated and compared in this paper. When back-EMFs and currents exhibit high order harmonics, the sensorless control performance might suffer from significant reduction in position estimation accuracy. In order to obtain the influence of harmonics, the position estimation results by both sensorless control strategies are compared and validated by experiments. It has been concluded that due to the high noise rejection ability of simplified EKF, better position estimation is obtained compared to FO counterpart.