Rotor position and speed estimation for PMSM

For traditional sensorless algorithm of permanent magnet synchronous motor (PMSM) is of complexity and disturbance, a novel way to estimate the rotor position and speed of PMSM based on sliding mode observer (SMO) is presented. Through estimating the electromotive force (EMF) in the stationary reference frame, the rotor position and speed were gained by the phase lock loop (PLL), which were contained in the EMF; and this method compensated for the phase lag caused by the angle estimation. Then a Lyapunov function was established to prove the sliding mode observer convergence. This method also improved the robustness and made the algorithm easy. It is thoroughly tested by establishing high performance full digital sensorless vector control system of the PMSM. The experiments show that this method, which can solve the uncertainty and disturbance in estimating rotor position in the transient state, is more robust and easier to be applied.