Abstract: With the improvement of electric vehicle technology and higher requirement for integrated performance, auxiliary power units (APUs, such as air conditioning system, electric power steering system, braking system and cooling system, etc.) will play more and more important functions. The analysis of APUs’ energy flow change during vehicle running can consummate the energy flow management of full vehicle. The work characteristics of APUs is analyzed, APUs models are built by using ADVISOR software based on energy consumption map. The threetypes of APUs models adapt to the traditional bus, serial HEV and parallel HEV bus, which improve the vehicle model accuracy. Then the APUs’ economic effect on the full vehicle is simulated, the results indicate that APUs occupy quite a few proportion of the energy consumption in the vehicle. In the USA city cycle, ECE cycle and Wuhan city bus cycle, the energy consumption of APUs occupies 6.1%~10% of the whole consumption.

Key words: Auxiliary power units, Hybrid electric vehicle, Modeling, Simulation