Research on Unified Method of SVPWM and SPWM for ANPC-5L Inverters

The unified theory between sinusoidal carrier based modulation (SPWM) and space vector pulse width modulation (SVPWM) in Active Neutral-Point-Clamped 5-level inverters (ANPC-5L) still lacks systematic analysis and research. After analyzing its topology and switch sequence, a modulation wave decomposition strategy is proposed to address its characteristic of multiple redundant switch states in phase voltage. This method determines the level state of each phase through modulation wave decomposition, and can effectively balance the voltage of the flying capacitor. By injecting a zero sequence component into the three-phase sine modulation wave and decomposing the sub modulation wave based on the degree of freedom of the switching tube, the signal after SPWM is directly used to trigger the opening of the switching tube, thereby obtaining a unique determined switching sequence that has the same control effect as SVPWM, achieving the unity of SVPWM and SPWM. The experiment verified the correctness of the theory.