A Novel Virtual Space Vector Modulation with Reduced Common-Mode Voltage and Eliminated Neutral Point Voltage Oscillation for Neutral Point Clamped Three-Level Inverter

This paper briefly reviews the common-mode voltage (CMV) and neutral point (NP) voltage of neutral point clamped three-level inverter (NPC TLI). Then, the space vector pulse width modulation (SVPWM) and traditional virtual SVPWM (VSVPWM) are discussed in term of these two issues, revealing the shortcomings in reducing CMV or eliminating NP voltage oscillation. To reduce CMV and eliminate NP voltage oscillation for NPC TLI simultaneously, a novel virtual space vector modulation, called as RCMV_VSVPWM, is proposed in this paper. By selecting vectors with lower CMVs, a set of novel virtual voltage vectors are generated. The method is featured with zero average NP current in one control cycle and lower CMV. Further, the active NP voltage control suitable for RCMV_VSVPWM is presented and evaluated. The corresponding experimental results are given, which are well consistent with the-oretical analysis.