Improved Sensorless Control for Linear Flux Switching Permanent Magnet Motor with Unbalanced Inductance

An improved sensorless control for linear flux switching permanent magnet (LFSPM) motor is proposed in this paper. Due to the end effect, the 3-phase inductance of LFSPM motors are unbalanced, which leads to an obvious reduction of observation accuracy of mover position and speed in sensorless control. To solve this problem, an improved phase-locked loop is proposed, in which a notch filter is connected in series in front of the PI controller. So the position estimation error of sensorless control for LFSPM motor can be reduced greatly. Besides, considering the complex operating conditions of the LFSPM motor, an active disturbance rejection control controller is adopted for the speed loop, which can avoid overshoot and improves the robustness of sensorless control. The simulation results verify the effectiveness of the proposed method.