Research on neutral-point voltage balancing in a three-level ANPC inverter based on sliding mode control and zero-sequence voltage injection

Abstract

To address the efficiency optimization and neutral-point voltage balancing issues in three-level active neutral-point-clamped (ANPC) inverters, this paper proposes a neutral-point voltage balancing strategy based on sliding mode control (SMC) and zero-sequence voltage injection. After the generation of modulation signals, a zero-sequence voltage compensation term produced by the sliding mode controller is directly superimposed onto the three-phase modulation waves. The proposed approach indirectly regulates the neutral-point current and coordinates the original zero-sequence component to maintain the linear modulation range while achieving neutral-point voltage balance. A three-level ANPC inverter model is established in SimuNPS for simulation verification. The results demonstrate that the proposed method effectively improves dynamic performance, enhances robustness, and suppresses neutral-point voltage fluctuations under load disturbances.