The auxiliary power supply system is an important part of the China standard EMU (Electric Multiple Units). It is mainly composed of auxiliary converters, chargers, battery packs and several loads. According to the topology of the EMU real auxiliary power supply system, the whole simulation system including the auxiliary converter, charger, single-phase inverter and other single models is built, and the internal working principle and working process of the system are studied. The auxiliary converter adopts the droop control method introducing virtual impedance to reduce the circulation effect of the parallel system. Combined with the battery pack charging characteristic curve, the constant current and constant voltage step-by-step charging management strategy is studied. The actual operating conditions of the system are simulated according to the auxiliary power supply system control logic. The system-level simulation on the MATLAB/Simulink platform shows that the output performance of each component is good, working in the rated parameters and meeting the working requirements of the auxiliary power supply system. Finally, the rationality, stability and robustness of the auxiliary power supply system model are proved by simulation and experimental comparison. This research provides a certain theoretical basis for the research of China standard EMU auxiliary power supply system, which has a certain significance.Electronics 2019, 8, 647 2 of 18 subway. A new control method of single-phase Phase-Locked Loop (PLL) function for the electrified railway converter system was presented in reference [2]. This method has been implemented on the converter of the auxiliary power supply system for the 8200 series electric locomotive in Korea. In reference [3], a composite control algorithm for the CRH2 EMU auxiliary power supply system was designed. The double closed-loop control algorithm based on current decoupling was used for the four-quadrant rectifier, while the double closed-loop control and repetitive control was designed for the three-phase voltage inverter. This control algorithm improved the stability and reliability of the auxiliary power supply system and its effectiveness has been verified through simulation and experiments. In reference [4], the loss model of the 1500 V power subway auxiliary inverter was established. The author estimated loss and efficiency of SiC MOSFET and Si IGBT systems under different switching frequencies. Analysis showed that the application of the SiC MOSFET could reduce the loss and improve the efficiency of the system. The SIC MOSFET was used to improve the topology of the auxiliary power supply system of the rail vehicle in reference [5,6]. It simplified the design of the converter, improved the working efficiency, reduced the switching loss and decreased the heat dissipation, benefiting the development of environmentally-friendly society. A simulation model of the EMU auxiliary converter system was established in reference [7]. It mainly introduced the implementation methods of HIL ...