Differential-Mode Circulating Current Suppression for Paralleled Inverters Fed PMSM Drives Considering Dead Time Compensation
Shichao Zhou, Kan Liu, Jiaming Wu, Kaiqing Li, Chao Huang, Dinghua Zhang
Abstract
Paralleled inverters are widely employed in permanent magnet synchronous machine (PMSM) drives to increase system capacity and reliability. Due to the discrepancy of paralleled inverters, the differential-mode circulating current (DMCC) is a major concern in paralleled inverters fed PMSM drives. The DMCC would result in current unbalance and efficiency reduction. To address this issue, a low-frequency DMCC suppression considering dead time compensation is proposed in this article, which can be effective in the suppression of both DMCC and zero-sequence circulating current. In detail, the DMCC due to the discrepancy of control settings, such as dead time and switching period, is eliminated by a proposed dead time compensation. Besides, the DMCC owing to the hardware differences, including device voltage drops, device turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on/off</small> delays, and filter inductances, is suppressed by a proposed regulation of phase conduction time, being free of disturbing the command voltage of drive system. Finally, the effectiveness of the proposed method is experimentally validated under both two-level and three-level space vector modulations.