Improved Space Vector Modulation for Neutral-Point Balancing Control in Hybrid-Switch-Based T-Type Neutral-Point-Clamped Inverters With Loss and Common-Mode Voltage Reduction

Abstract

This paper compares different space vector modulation (SVM) strategies for neutral-point voltage balancing (NPVB) control in three-level (3-L) T-type neutral-point-clamped (TNPC) inverters, and proposes an improved SVM trimmed for NPVB control in hybrid-switch-based 3-L TNPC inverter with the features of loss and common-mode voltage (CMV) reduction. The proposed SVM strategy uses a new principle of small vector selection and vector sequence, and thus, it can balance the neutral point (NP) potential and achieve soft-switching of clamping leg simultaneously. The paper includes detailed analysis for circuit commutation mode, loss breakdown, and common-mode voltage patterns under different operation conditions. The circuit simulations and experiments are carried out in the last part of this paper to validate the proposed SVM strategy. Index Terms-Electromagnetic interference (EMI), neutralpoint (NP) voltage balance, Si-SiC hybrid switch, space vector modulation (SVM), T-type neutral-point-clamped (TNPC) inverter, wide bandgap (WBG) devices.