Identification and Compensation of Force Ripple in PMSLM using a JITL Technique

Abstract This paper presents an adaptive compensation scheme for reducing the force ripple effects in permanent magnet synchronous linear motor (PMSLM). Firstly, when the velocity of a linear motor is close to zero, based on a fast Fourier transform (FFT) analysis, the dominant displacement periodicity of the force ripple can be obtained for simplifying the ripple model. Next, to enhance the identification accuracy and guarantee the real‐time performance of the linear servo system simultaneously, an improved just‐in‐time learning (JITL) algorithm is proposed to estimate the ripple model parameters. Finally, based on the identification results, an adaptive feedforward controller is implemented in the linear servo system to compensate the force ripple. The main motivation of this paper is the extension of the identification methods to improve the servo control performance in industrial applications. Simulation and experimental results demonstrate the effectiveness of the proposed method, even when compared to a traditional compensation method based on a recursive least squares algorithm.