Static Characteristic Analysis of Proposed Bi-Directional Dual Active Bridge DC-DC Converter

Recently, increased attention is being paid to power supply networks using energy storage devices such as batteries. Network topologies using bi-directionalisolated DC-DC converters of low or medium capacity are required for the diversification of power supply networks. The dual active bridge (DAB) DC-DC converter is one of the most effective bi-directional isolated DC-DC converters. However, the circuit has some inherent problems such as degradation of power efficiency and the occurrence of surges during light-load operation. In this paper, we propose a control technique to solve these problems. From the experimental results, it is confirmed that the maximum power efficiency improvement was 16% for a light load. Applying two operation modes, the proposed operation in light load and the conventional operation in heavy load, the circuit can be operated across a full range of road. To switch between the two modes seamlessly, the precise boundary point of the two modes is needed for feedback control. Therefore, a precise static characteristic analysis with loss was carried out. From the results, the loss included simple equivalent circuit model was obtained. The root mean square error between the proposed analysis and the experimental results is within 4%.