A Sensorless Control System of PMSM Based on LADRC and SMO

A method of sensorless active disturbance rejection control based on SMO was proposed, in order to further improve the estimation accuracy of rotor state, observe the robustness of rotor and improve the sensorless speed control performance of PMSM. Firstly, based on the mathematical model of PMSM stator current in a-ß coordinate system, an improved SMO was designed to effectively estimate the rotor state of PMSM and reduce the buffeting effect of sliding-mode switching and the estimation delay of rotor state. According to the resistance parameter variation disturbance of motor system, estimation error of rotor state and load disturbance, by using the state equation of PMSM in d-q rotating coordinate system, the linear active disturbance rejection controllers (LADRC) for current loop and speed loop were designed respectively. Based on the double closed-loop active disturbance rejection control, the impact of disturbance and estimation error of rotor state on sensorless control performance was prevented, thereby enhancing the sensorless speed control performance and robustness of PMSM. The effectiveness and advanced characteristics of the proposed method is verified by the simulation results.