Sensorless control for PMSM with combined IF and improved sliding mode observer

In order to realize the full speed range operation of the sensorless control for permanent magnet synchronous motor(PMSM), a composite control of IF control combined with improved adaptive sliding mode observer is proposed. The adaptive sliding mode observer obtained the estimated value of the rotor flux linkage by introducing the participation of the electrical angular velocity, thereby obtaining the rotor position and the rotational speed. According to the IF open-loop control theory, a single-current closed-loop IF control was established based on the instantaneous reactive power, which improves the current utilization. When the direction of motor speed changed, the position error of plus or minus 180° caused by the traditional phase-locked loop is avoided by using the phase-locked loop based on tangent function. A linear weighting function was used to achieve smooth switching between the two controls. The composite control strategy improves the estimation accuracy and stability of the full speed range, reduces buffeting, improves the system robustness, and avoids the error of rotational speed reversal. Simulation and experimental results verify the effectiveness and practicability of the proposed method. © 2020, Harbin University of Science and Technology Publication. All right reserved.