Equivalent neutral point voltage control strategies in neutral-point diode-clamped three-level converter

This paper shows the equivalent of different strategies in neutral point voltage control under different modulation methods --- CBPWM and SVPWM. With this concept we can go from one strategy in CBPWM to another in SVPWM freely, and also newly found strategies that will be used not only in CBPWM but also in SVPWM. A simple neutral current model is established to analyze the problem of unbalance of neutral point voltage. Two couples of strategies based on different modulation methods are compared to show the equivalent. Two new strategies that can be used in both CBPWM and VPWM are proposed. Simulation results are given to show the feasibility.