Harmonic Suppression Based on Rectified Current Regulation With DC-Link Voltage Decoupling for Electrolytic Capacitorless PMSM Drives

Harmonics suppression for grid currents is a key issue in electrolytic capacitorless permanent magnet synchronous motor drives. In this article, a strategy based on rectified current regulation with dc-link voltage decoupling (RCR-DVD) is proposed to enhance the harmonics suppression performance of grid currents. The small-signal model of the drive with RCR is built to reveal the disturbance caused by the dc-link voltage and digital control delay, which may reduce the harmonics suppression capability and lead to stability issue. Then, the RCR-DVD is proposed to decouple the voltage disturbances from rectified current control loop for better harmonics suppression performance. Specifically, the voltage decoupling is realized by main harmonics prediction and proportional resonance controllers. The amplitude of grid-side input impedance can be increased compared with RCR, which means lower grid current harmonics. Experimental results validate the effectiveness of the proposed method.