Design of Onboard 270V/28V DAB Converter for Optimized Parasitic Paramters

The aviation power supply system with HVDC standard (270V) needs to realize power supply to LVDC (2SV) loads through step-down DC/DC converters. On the other hand, the power from LVDC bus needs to be stepped up and delivered to HVDC loads during power interruption of HVDC bus. The DAB converter is a good solution to meet this need, due to the advantages of bidirectional power flow, soft switching, fewer passive devices, and wide-range voltage regulation. Switching frequency is increased to increase power density, which makes the negative effects of parasitic parameters more serious. In this paper, the influence of transformer parasitic capacitance on high-frequency oscillation (HFO) is analyzed by impedance model of magnetic tank. Then, transformer design approach for controlled parasitic parameters is proposed. Moreover, optimized layout is introduced to mitigate voltage and current spikes caused by parasitic inductance. The proposed design is verified by a 500W270V/2SV prototype.