A fast multi-level space vector PWM method based on sequence cyclic shift

Multi-level technology has good application prospects in high-voltage high-power occasions. Compared to sinusoidal PWM (SPWM), space vector PWM (SVPWM) has many advantages. However, conventional SVPWM will be too complex when level number is larger than five. In this paper, A new multi-level SVPWM method is proposed for cascaded H-bridge converters. This method implements multi-level SVPWM by cyclically shifting the switching-state sequence obtained by two-level SVPWM in one sampling cycle. Therefore the proposed method requires calculating for only once in one sampling cycle by two-level SVPWM algorithm. This method can achieve a DC voltage utilization ratio as high as conventional SVPWM and a lower THD than carrier-phase-shifted sinusoidal PWM. Furthermore, the equivalent switching frequency is also raised. This paper analyzes the principle and the implementation of this sequence-cyclic-shift SVPWM. Simulation and experiment were performed and the results show the validity of the proposed method.