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

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.