Neutral-point potential balance control strategy of three-level active neutral point clamped inverter based on zero-sequence voltage injection

The advent of Active Neutral Point Clamped (ANPC) inverters has increased the switching frequency. However, like the Neutral Point Clamped (NPC) type converter, the problem of midpoint voltage imbalance also exists in the three-level ANPC converter. The reason for the neutral-point potential imbalance is that the load current generates an AC current on the midline of the three-level inverter through each phase bridge arm. In order to solve this problem, the article takes the three-level ANPC inverter as an object, analyzes the reasons for the imbalance of the midpoint potential on the Direct Current (DC) side of the three-level ANPC converter and introduces a unified midpoint balancing control method under the space-vector pulse-width modulation from the angle of the zero-sequence component of the modulating waveform.