Study On Energy Management Of Fuel Cell And Ultracapacitor Hybrid Power System

In recent years,non-renewable energy is becoming increasingly scarce,and the emergence of new energy vehicles has broken this situation.The fuel cell vehicle is driven by hydrogen,and its operation process is green and pollution-free.In the future,it will become the mainstay of new energy vehicles.Fuel cell vehicle has low noise,no emission of any pollutants,and high energy efficiency.It will certainly become an ideal power source to replace traditional fuel cars in the future.Fuel cell hybrid electric vehicle can make full use of the advantages of high energy density of fuel cell and high power density of auxiliary power source,and meet the dynamic and economic requirements of the vehicle when it is driving in complex road conditions and needs frequent acceleration and braking.In this paper,the structure of fuel cell and ultracapacitor hybrid electric vehicle is determined by referring to the previous power structure of fuel cell hybrid electric vehicle.According to the design objectives of parameters of a certain vehicle type,all parts of the vehicle were selected and matched,including parameters of fuel cell,ultracapacitors and driving motor.Then Matlab/Simulink software was used to build off-line simulation models for various components of the power system,including fuel cell model,supercapacitor model,DC/DC converter model,vehicle dynamics model and driver motor model.Secondly,in order to improve the energy utilization rate of the vehicle as well as the economy and power of the vehicle,the energy management strategy of the power system was studied,and a fuzzy control strategy based on logic threshold was proposed.The proposed control strategy and the traditional fuel cell vehicle control strategy — power following control strategy — were used for offline simulation under UDDS cycle and NEDC cycle conditions.The simulation results preliminarily verified that the fuzzy control strategy based on logic threshold was superior to the power following control strategy in terms of economy and power performance.Finally verified test bench,the results show that the presented control strategy is effective and authenticity,in the fuel cell and super capacitor hybrid power system adopt fuzzy control strategy based on logic threshold,the super capacitor play to the characteristics of high power density,This strategy can give full play to the high power density of ultracapacitors.Under this strategy,the instantaneous power with large variation can be separated,and the ultracapacuity can supplement the disadvantage of insufficient power output and slow response of the fuel cell,making the fuel cell output flat and increasing the power performance and economy of the vehicle.