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 the HSPMSM, which makes the traditional capacitor-voltage-feedback-based active damping fail. To achieve the desired resonance damping effects, the discrete-time-model-based multistate feedback active damping is proposed, which can configure the resonance pole arbitrarily. Then, to solve the serious cross coupling under low carrier ratios, a low-frequency-equivalent-transfer-function-based dynamic decoupling method is proposed for the parts where the traditional decoupling method cannot be applied. On the above basis, an outer-loop proportional–integral controller is adopted to adjust the magnitude and phase of the open-loop 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 the HSPMSM. Finally, the effectiveness of the proposed method is verified by experiments.