Speed sensorless control of bearingless permanent magnet synchronous motor

A composite observer method using high frequency signal injection and extended Kalman filter (EKF) is presented to estimate the rotor position and speed for bearingless permanent magnet synchronous motor(BPMSM). The very low speed and standstill performance of the drive is further enhanced by using high frequency signal injection. The high speed of the drive is using EKF. By designing speed switch, it can achieve smooth switching between the two methods. The proposed method is capable of exhibiting high dynamic and steady-state performances over a wide speed range. Experimental results confirm the effectiveness of the proposed method.