Simple balancing method for unbalanced dual-bridge converters based on fundamental harmonics approximation and trigonometric calculation

Abstract

Three-phase Dual-Active-Bridge converters use a three-phase transformer for isolation and voltage leveling. Due to fabrication, the inductance in the transmission path of each phase may be different from each other. If the difference is large enough, the current may be unevenly distributed among phases that lead to the unbalance in loss and heat distribution of power switches and transformers. This paper proposes a simple current balancing method among phases for three-phase Dual-Active-Bridge converters due to inductance mismatch in the transmission path. The method is based on first harmonic approximation and trigonometric calculation of the phase shift for each phase. Simulation and experimental results show that the proposed method can help balance the phase current effectively.