Bidirectional Dual-active DC-DC Converter Based on Traction Auxiliary Power Supply System

The auxiliary power supply system is used to supply the power to the electric equipments, like the lighting and the heating equipments, etc and plays an important role in the normal operation of the Electric Multiple Units (EMU). As to the generalized auxiliary converters, it is difficult to achieve their lightweight design due to their properties of large capacity and volume. To address this issues, an improved auxiliary converter is proposed in this paper, which has the following advantages: 1) The proposed topology directly takes power from the DC high-voltage bus and effectively reduces the conversion order of the entire converter. 2) The charger adopts bidirectional isolated DC-DC converter to realize bidirectional energy transmission, which can overcome the disadvantage that the traditional structure cannot maintain the power supply of the AC bus when the pantograph loses power. In addition, for the DC-DC converter and inverter in this structure, the corresponding mathematical models are established and the related control strategies are applied to ensure the whole system normal operation and finally verified by simulation and experimental results.