Logarithmic Sliding-Mode Observer and Controller for Position Sensorless PMSM Drive

Accurate acquisition of rotor position information is vital for sensorless field-oriented control (FOC) of the permanent magnet synchronous motor (PMSM). The sliding-mode observer (SMO) method is widely used in medium- and high-speed motor operations due to its straightforward implementation and robustness. However, the discontinuous control law leads to chattering phenomenon which reduces the accuracy of position estimation. In this paper, the logarithmic sliding-mode (LnSM) observer is proposed for estimating rotor position and the super-twisting algorithm (STA)-based LnSM (STA-LnSM) controller is designed to achieve fast and high-precision tracking of motor speed. Compared with the traditional SMO and PI controller, the proposed strategy significantly eliminates the effect of chattering phenomenon on the accuracy of rotor position estimation and improves the dynamic performance of the system. Finally, the effectiveness and superiority are verified by simulation.