Improved Rotor Flux Observer With Disturbance Rejection for Sensorless SPMSM Control

Voltage and flux model-based rotor flux estimation has been extensively applied in sensorless surface-mounted permanent magnet synchronous motor (SPMSM) drives. Considering that the performance of the position estimation is undoubtedly influenced by dc offset from initial conditions and integration drift from current measurements, which are serious threats to the stable operation of a sensorless control system. To tackle this problem, this article proposed an improved rotor flux observer to suppress the deviation of rotor flux estimation, using the steepest descent optimization to minimize the error between the estimated rotor flux and PM flux linkage to realize disturbance compensation, which leads to its robustness against the dc disturbance existed in the pure integration method. Furthermore, motivated by the model predictive control (MPC), the flux-oriented finite position set phase-locked loop (FO-FPS-PLL) based on dichotomy, which combines with the spatial relationship between the estimated and reference synchronous rotating frame, is applied for sensorless SPMSM drives. Finally, the experimental results based on a 1 kW PMSM drive platform validate the proposed sensorless control scheme.