Design of a Bi-directional DC-DC Converter for High-efficiency Emergency Self-traction of High-speed Railway Trains

The emergency self-traction function of high-speed railway electric multiple units (EMU) trains is very important for maintaining the railway transportation order and passenger safety under emergency situations especially power failure. The improvement of energy conversion efficiency between on-board energy storage device, traction motor and auxiliary power supply equipment is one of the key research topics. This paper proposes a bi-directional converter for emergency self-traction and designs its topology as well as control strategy. The converter can withstand higher voltage and current levels, realizing the direct connection between the 110V low-voltage energy storage battery and the 3000V high-voltage DC bus with bi-directional power flow capability, which reduces the power loss of the emergency traction as a result of shorter power flow path. The corresponding power supply control scheme is presented under different working conditions so as to ensure the normal power supply of auxiliary equipment and the demand of traction power supply in emergency. The effectiveness and stability of the proposed converter and control strategy are verified by MATLAB/Simulink simulation and experiments on RT-LAB platform.