Improved Adaptive Law-Based Sliding Mode Observer for Sensorless Control of PMSM

In order to improve the dynamic response performance and reduce the steady-state error, this paper proposes an improved adaptive law-based sliding mode observer (SMO) for the sensorless control of permanent magnet synchronous motor (PMSM). The SMO based on conventional adaptive law can estimate rotor position without the phase shift, but it is not suitable for sensorless speed close-loop control because of its poor dynamic performance. In this paper, the adaptive law is improved to deal with this issue. The stability of the improved adaptive observer can be proved by the Lyapunov stability theory. The experimental results show that the proposed method can track the changes of rotor speed and position with good characters, such as fast convergence and little chattering.