Thrust Fluctuation Suppression of PMSLM Considering Flux Linkage Harmonics and Cogging Force

This paper investigates the thrust fluctuation for permanent magnet synchronous linear motors (PMSLMs). In this paper, a new control method is proposed to suppress thrust fluctuation caused by permanent magnet flux harmonics and cogging-force. Firstly, two generalized integrator-extended state observers (GI-ESO) are used to estimate back electromotive force and the cogging-force respectively. Then add a parameter $k_{c}$ to the controller of the current loop. $k_{c}$ varies with the magnetic flux parameter of the permanent magnet to suppress the thrust fluctuation caused by permanent magnet flux harmonics. In addition, a feedforward signal is added to the current loop to compensate for cogging- force. Suppressing thrust fluctuation requires the current to contain harmonics. The resonant controller of the current loop can enhance the system’s ability to follow certain frequencies of current. So a resonant controller is added to the current loop. Finally, the simulation results show that the proposed method can effectively suppress thrust fluctuation of PMSLMs.