Compensation and Rejection of Cogging Torque of PMSM Based on Novel Internal Model Observer in Series With Extended State Observer

In order to reduce the influence of cogging torque on the control performance of permanent magnet synchronous motor (PMSM) servo system, an internal model observer in series with extended state observer was proposed to achieve better cogging torque observation and disturbance compensation control. By modeling the cogging torque and analyzing the amplitude-frequency characteristics of the observers, it is pointed out that the conventional observers have problems such as poor periodic disturbance observation, low-frequency disturbance amplification, high system order and strict bandwidth requirements. Theoretical derivation, simulation calculation, experimental verification and comparative analysis were carried out for the proposed observer, and it can be proved that the series form of the extended state observer for estimating the low-frequency disturbance and the internal model observer for estimating the cogging torque is excellent at disturbance observation. The proposed observer was applied to the PMSM servo system. Therefore, the speed fluctuation and tracking error can be reduced by about 40%, and the bandwidth of the observer can be reduced by about 60%. Meanwhile, the stability of the algorithm and the ability of rejecting low-frequency disturbances can be enhanced. ©2022 Chin.Soc.for Elec.Eng.