Common-Mode Voltage Reduction and Neutral-Point Voltage Control Using Space Vector Modulation for Coupled Ten-Switch Three-Phase Three-Level Inverter

Abstract

Space vector pulsewidth modulation (SVPWM) provides enhanced performance for the coupled ten-switch three-phase three-level inverter (TP-TLI). However, it suffers from high common-mode voltage (CMV) and unbalanced neutral-point voltage (NPV). To solve this problem, a CMVR_SVPWM with CMV reduction and NPV control (NPVC) is proposed in this article. By using suitable vectors with lower CMVs and sequences, the amplitude of CMV is suppressed to 50% of the previous strategies for ten-switch TP-TLI. A newly control degree is explored to regular the NPV through the two pairs of newly virtualized vectors in each sector. The dwell time of each selected vector is indirectly calculated to cooperate the NPVC with the CMVR_SVPWM. By enhancing the dwell time of the desired small vector, the NPV can be balanced while maintaining the almost same output quality. The dead-time effect is analyzed, and the resulting CMV spikes is eliminated by increasing the dwell time of the vector which is less than twice the compensation time. It preferentially attempts to eliminated the CMV spikes based on volt-second balance. This minimizes the effect of the proposed compensation method on output quality. A 3-kVA experimental prototype is built up to verify the feasibility and performance of the proposed CMVR_SVPWM.