Common Mode Decoupling Control Strategy for A Three-phase Transformerless AC-DC Converter with Independently Controlled Neutral Module

With the popularity of various types of loads based on DC power supply, low-voltage AC and DC hybrid distribution networks have become an efficient solution for future distribution systems. The bidirectional interface converter is a key device. When the AC and DC sides of the distribution network are grounded, the AC and DC coupling of the converter will cause common mode voltage and leakage current, endanger personal safety, and reduce power quality. This paper proposes a new three-phase non-isolated AC-DC converter common ground topology, which can eliminate the common-mode voltage of traditional converters due to AC-DC coupling. However, common ground will cause neutral current, and this paper also proposes a control strategy for neutral current suppression. Finally, the effectiveness of the proposed method is verified by detailed simulations.