LEU及应答器能否正常输出报文,是高铁线动车运行安全的重要保证,其中LEU及其切换电路是车地通信链路中的重要一环。通过对目前既有冗余LEU切换电路存在的设计缺陷进行分析,发现LEU“软故障”是影响动车组正常运行的根本原因,从而通过对LEU切换电路的改进及相应的软件修改,克服了目前既有高铁冗余LEU切换单元存在的缺陷。 Whether the LEU and the transponder can output the message normally is an important guarantee for the operation safety of the high-speed railway line motor car. The LEU and its switching circuit are important links in the car-ground communication link. Through the analysis of the existing design flaws of existing redundant LEU switching circuits, it is found that LEU “soft fault ” is the root cause that affects the normal operation of the EMU. Therefore, by improving the LEU switching circuit and corresponding software modification, At present, there are defects in LEU switch unit of high-speed rail redundancy.