Objective In the auxiliary power supply system of urban rail transit vehicles, the energy consumption of air conditioning system accounts for a relatively high proportion. With the popularity of inverter air conditioning, the traditional three-phase AC 380 V auxiliary power supply scheme suffers from issues such as low power conversion efficiency and high harmonic interference. It is necessary to study an integrated solution to improve energy efficiency and reduce operating costs.

Method On the basis of summarizing the current status of auxiliary power supply systems in China, the power supply principle of integrated power supply air conditioning unit is elaborated. Namely, the vehicle-provided DC 1 500 V power supply can be directly utilized by integrating the air conditioning unit and the fusion power supply module. On one hand, the DC 1 500 V power supply is converted into the variable frequency three-phase AC power supply required by the air conditioning unit to drive its various components; On the other hand, the DC 1 500 V power supply is converted into three-phase AC 380 V and DC 110 V power supply for the lighting system, air compressors and cooling fans, etc. The structure of the integrated power supply air conditioning unit is further introduced, and its technical characteristics are summarized as following: the system eliminates the intermediate stages of filtering, rectification and inversion through topology simplification, improving power conversion efficiency by about 10.0%.

Result & Conclusion  By directly utilizing the DC 1 500 V power supply provided by vehicles, the integrated power supply air conditioning units eliminate the auxiliary power supply system for urban rail transit vehicles, simplify the power conversion process, and improve the power conversion efficiency, thus solving problems such as low efficiency and poor compatibility in traditional power supply systems. Calculation results show that the integrated power supply scheme can reduce the energy consumption of the air conditioning system by about 10.0%, leading to an annual energy saving of 2.5% for the entire vehicle.