Sensorless Position Correction Strategy of PMSM Based on Variable Operating Point in Constant Torque Curve

Some non-ideal factors often lead to rotor phase error in sensorless control system of permanent magnet synchronous motor (PMSM). Aiming at the positioning error caused by motor parameter mismatch and control delay, this paper proposes a rotor position correction method based on the equal torque relationship between multiple working points under the same working condition. The output torque is expressed as a function of the position error. By changing the working point, two torque equations containing the positioning error are obtained. According to the constant torque characteristics of PMSM,only when the torques of the two operating points are equal, the orientation becomes accurate. Therefore, the position error is calculated according to the moment equality equation of the two working points. Since the change of motor parameters will affect both sides of the torque equation, the calculation error caused by the change of parameters can be offset, and the robustness of the proposed method is improved. Finally, the simulation results verify the effectiveness of the proposed method.