Performance Analysis of Zero-Sequence Voltage Balancing Methodologies in Grid-Tied NPC Converters for EV Charging Systems

The performance of zero-sequence voltage compensation algorithms in a three-phase neutral point clamped (NPC) converter acting as an interface between a DC charger for electric vehicles and the grid has been modelled, simulated and experimentally validated. In particular, the analysis of zero-sequence voltage methods has been investigated, as they provide an effective solution to this problem regardless of the modulation technique used. This study focuses on the development of an electric vehicle charging station supplied by an NPC converter, where both the linear control of the DC voltage unbalance and the optimal zero-sequence voltage detection methods are studied. Finally, the results obtained from the implementation of linear control of the DC voltage unbalance is reported.