Three-Phase Flying Capacitor Clamped Current Source Converter With Active Capacitor Voltage and CMV Control

AC-type flying capacitor (FC) concept has been proposed for current source converter (CSC) topologies recently, which offers unique merits over the traditional CSCs, such as lower dv/dt with improved dc-link voltage quality as well as flexible common-mode voltage (CMV) control. To cope with the main-stream three-phase industrial applications, in this article, the three-phase flying-capacitor-clamped CSC is introduced and extensively investigated for the first time. A novel space vector modulation is proposed, featuring a modular design process, active FC voltage control, and CMV suppression. The detailed commutation principles and the capacitor clamping voltage influence under different switching states are comprehensively addressed. Then, the redundant switching states are optimized to fulfill the multiple targets simultaneously. Simulation and experimental results are performed to demonstrate the superior dc-link power quality and CMV performance compared with the traditional three-phase CSC topology.