Discrete-Time-Model-Based Dynamic Decoupling Active Damping Current Control for CSI-Fed High-Speed PMSM With Low Carrier Ratio

This article proposes a dynamic decoupling active damping current control method for the current source inverter (CSI) fed high-speed permanent magnet synchronous machine (HSPMSM) drive with low carrier ratios. In this system, the natural resonance frequency is relatively high compared with the conventional CSI-fed system due to the high fundamental frequency and low inductance of HSPMSM, which makes the traditional capacitor voltage feedback based active damping fail. To achieve the desired resonance damping effects, the discrete-time model based multi-state feedback active damping (MSFAD) is proposed, which can configure the resonance pole arbitrarily. And then, to solve the serious cross-coupling under low carrier ratios, a low-frequency equivalent transfer function (LFETF) based dynamic decoupling method is proposed for the parts where the traditional decoupling method cannot be applied. On the above basis, an outer-loop PI controller is adopted to adjust the magnitude and phase of the openloop transfer function. In this way, the desired open-loop cutoff frequency with enough phase and gain margin can be achieved under the wide fundamental frequency changes of HSPMSM. Finally, the effectiveness of the proposed method is verified by experiments.