Design Of Control Algorithm For The Power Supply System Of Fuel-Cell Electric Vehicle

As the energy crisis and environmental pollution problems are becoming increasingly serious these days,the development of new energy vehicles attracts attention of the world,the fuel cell electric vehicle whose main power energy source is proton exchange membrance fuel cell system becomes famous for its unique environmental protection characteristic.In fact,the auxiliary energy source such as a battery or an ultracapacitor must be introduced into the fuel cell power system because of its dissatisfactory output characteristics and slow response.In this thesis,a power control strategy based on DC voltage droop control and fuzzy logic were designed for the fuel cell vehicle power supply system,whose effectiveness was proved by simulation under different road conditions.The main contents are as follows:Firstly,the characteristics of the common energy storage in the electric vehicle power system were analyzed,the multi-energy hybrid power system structure was designed,and the key parameters of the power supply system were matched.Then the operating mode of the power system was analyzed in this thesis.Secondly,according to the power system structure,the topology of the two DC/DC converters was determined respectively.Then the operating mode and working theory of the DC/DC converters were analyzed,after which the parameters of the DC/DC converts were designed.On this basis,the average model of the converters is established,and the small signal dynamic model and transfer function of the current loop and the voltage loop were deduced respectively to design the controllers’ parameters.Finally,guaranteeing the stability and durability of the fuel cell,maintaining the reasonable battery SOC and ensuring the stability of the DC bus voltage were identified as the aim of the power control strategy.According to the ultimate aim,the three main factors which affect the power distribution were obtained,they were the output power of the fuel cell,the battery SOC and the DC bus voltage.At final part of the thesis,a power control strategy based on DC voltage droop control and fuzzy logic was proposed and validated by simulation under different road conditions.