A Phase-Shift PWM Based Zero-Sequence Voltage Injection Method for Neutral-Point Potential Balance of Five-Level ANPC Converters

The five-level active neutral-point clamped (5L-ANPC) converter is getting more and more attention in recent years. The zero-sequence voltage injection can be used to control the neutral-point (NP) potential and the voltages of flying capacitor (FC) are balanced by using redundant switching states properly. However, the NP potential control needs to be decoupled with the voltage balancing of the FC to achieve superior dynamic performance. To solve this problem, the relationship between NP current and zero-sequence voltage is presented, considering the difference of the duty cycles of redundant switching states. Therefore, a phase-shift PWM based zero-sequence voltage injection method for NP potential control is proposed in this paper. The results of simulation and experiment are shown to demonstrate the superiority of the proposed method.