2018 Ministry of Science and Technology Research Project (PI)

Topic—High-Efficiency and High Power Density, Isolated Bidirectional DC-DC Converter for Residential Energy Storage Systems

Abstract—This sub-project aims to design and implement a high efficiency, high power density (>1.5 W/cm³) Isolated bidirectional DC-DC converter. In order to achieve high power density, higher switching frequency is utilized. To achieve this, the selection of the power devices is important. Due to the fast switching characteristics of wide bandgap (WBG) power semiconductor devices, which reduces switching losses and improves efficiency, the power density can be increased. Higher switching frequency also allows for the use of smaller Magnetics. The operating principles of the selected converter topology and control strategies will be verified by computer simulation. In order to realize the proposed design, the preliminary planning work will focus on computer simulations, which will be used to evaluate and verify the proposed designs. Then, a high-performance prototype will be implemented to meet the requirements. For this project, we expected to implement an isolated bidirectional DC-DC converter, where the high side input/output voltage is 400 V, low side input/output voltage is from 35 V to 50 V, and output power is 1kW. The low voltage side’s current ripple must be smaller than 2 percent at full load when input is from the high voltage side. The high voltage side’s voltage ripple must be smaller than 3 percent at full load when input is from the low voltage side. At 25% load, the efficiency must be greater than 92%; at 50% load, the efficiency must be greater than 94%; at 100% load, the efficiency must be greater than 96%. The power density must be higher than 1.5 W/cm³, and the weight must be less than 1.5 kg.