Repetitive Disturbance Observer Based Composite Current Control for PMSM With Harmonic Reducer

The current control is the core to realizing fast response and high accuracy permanent magnet synchronous motor (PMSM) drive harmonic reducer (HR) system. However, the induced electromotive force, parameter variation, and deadtime effect will lead to the periodic/aperiodic disturbances as well as cross-coupling terms, which may largely deteriorate current control performance. To simultaneously suppress and compensate for the above multisource disturbances, a composite current control scheme based on the repetitive disturbance observer (DO) is proposed in this article. First, based on the characteristics of multisource disturbances, the repetitive control, the DO and the deviation decoupling are designed to deal with the periodic disturbance, aperiodic disturbance, and the cross-coupling term, respectively. Then, the stability of the closed-loop system is analyzed according to the characteristic roots distribution. Furthermore, the disturbances rejection capability is quantified by the transfer function amplitude, and the range of control gains are determined by the sampling time and system parameters. Finally, the effectiveness of the proposed scheme is experimentally validated on a PMSM drive HR platform.