Three-Port Converter with Leakage Inductance Energy Recycling for High Step-Down Applications

An emerging revolution in electric vehicles (EVs) is rapidly taking over the traditional fossil fuel vehicle market. Given its safety features and user-friendliness, the dual battery system (DBS) has been adopted in various EVs. A step-down three-port converter is essential for the DBS to supply low-voltage auxiliary power in EVs. In this paper, a novel high step-down three-port converter (TPC) is proposed by integrating the tapped-inductor technique and a buck converter for fulfilling the requirements of high step-down power conversion from sources to load with a reasonable duty cycle. It can also achieve independent power transfer among three ports. In addition, the energy stored in the leakage inductance of coupled inductor is recycled, with voltage spikes reduced across the switches. Finally, an experimental prototype is built to verify the theoretical analysis, with a main battery of 300 V, auxiliary battery of 48 V, load voltage of 24 V, and rated power of 300 W. The highest efficiency reached is 96.6%.