Adaptive Robust Sensorless Control for PMSM Based on Improved Back EMF Observer and Extended State Observer

Calculating the back electro-motive force (EMF) in a synchronous permanent magnet motor (PMSM) is difficult for its drive control system. In this article, a sensorless robust control scheme combining an improved back EMF observer and an extended state observer (ESO) is presented. First, the back EMF equivalent signal is obtained by a sliding mode observer (SMO), and the improved back EMF observer (IBEO) is proposed based on the back EMF model. By contrast with the traditional back EMF observer, the proposed IBEO considers the uncertainty and dynamic components of the motor mathematic model, suppresses the signal chattering by the adaptive mechanism, and has a smaller estimation error and the faster convergence rate. Afterwards, an ESO is built to estimate the rotor position, the rotor speed and the total disturbance. Based on the ESO, the adaptive robust speed controller is designed. Additionally, the stability of the IBEO and robust speed controller are proved by the Lyapunov stability theory. Finally, the effectiveness and feasibility of the presented control scheme were verified by the experiment work. The sensorless control scheme showed the stronger antiinterference capability and robustness with small chattering.