Improved Grid Current Control Strategy Based on Q‐Axis Regulation and Phase Compensation for Reduced <i>dc</i> ‐Link Capacitance PMSM Drives With Large Line Inductor

ABSTRACT LC resonance is the primary cause of poor grid current quality in reduced dc ‐link capacitance permanent magnet synchronous motor (PMSM) drives with large line inductance. In this paper, a strategy of q ‐axis regulation and phase compensation based on a proportional resonance controller (QRPC‐PR) is proposed to suppress LC resonance and enhance the quality of the grid current. Initially, a small‐signal model is developed based on a simplified circuit of the drive system to elucidate the LC resonance. It results in the decreased power factor, increased harmonics in the grid current, and instability issue. Then, a damping compensation loop based on the deviation between ideal dc ‐link voltage and actual dc ‐link voltage is established to enhance the stability of the drive system, and the comparative analysis is conducted on the damping loop controllers with different parameters. In addition, by modifying the phase and amplitude of the dc ‐link voltage, the grid current quality is further improved. In comparison with conventional q ‐axis regulation strategies, the power factor is increased to 0.99, and the grid current harmonics are obviously reduced. Finally, experiments on PMSM drives without electrolytic capacitors verify the effectiveness of the proposed strategy.