Capacitor Voltage Balancing Method With Adaptive Mode Identification for Neutral-Point Clamped Dual-Active-Bridge Converter

Several voltage balancing strategies have been proposed for neutral-point clamped dual-active-bridge converter to decouple the inductor current from the balancing mode, thereby avoiding balancing failures caused by model mismatch. However, these strategies cannot maintain the steady-state waveform of the transformer voltage, leading to performance deterioration during the balancing process. Therefore, an adaptive mode identification method is proposed in this letter to realize decoupling while avoiding adverse performance impact. The current polarity required for selecting the balancing modes is identified without the current model. Meanwhile, the converter's performance can remain consistent with its steady-state operation. Finally, the robustness of the proposed method is verified by experiment.