Adaptive force ripple suppression for PMSLM based on improved REFOP algorithm

Permanent magnet synchronous linear motor (PMSLM) has been widely applied in the high-precision industrial fields. To reduce the influence of force ripple on the position accuracy of PMSLM servo system, an adaptive suppression scheme is proposed in this paper. Firstly, to simplify the mathematical model of force ripple, PMSLM keeps at the low and constant speed, thus the force current is analyzed by fast fourier transform to extract the characteristic frequency of force ripple. Secondly, to satisfy the real-time performance of PMSLM servo system, an improved recursive empirical frequency domain optimal parameter estimation is proposed to identify the model parameters of force ripple on line. Finally, based on the estimation of force ripple, an adaptive feedforward suppression controller is used to suppress force ripple. Simulation results show that, compared with the traditional identification method, PMSLM servo system using the proposed method owns faster convergence rate and better control accuracy.