Design Of Fuel Cell/Ultracapacitor Hybrid System And Research On Decentralized Energy Management Strategy

With the popularization of automobiles,the exhausting of non-renewable energy sources,and the problem of air pollution is becoming more and more serious,which has aroused widespread concern of people from all walks of life.Clean energy has great development potential.It has founded that fuel cell had this characteristic,so it has gradually become one of the mainstream vehicle energy.However,due to the slow dynamic response and unidirectional flow of energy of fuel cell,the performance of vehicle is affected seriously.Considering that the ulcapacitor has the advantage of high power density,we can form a hybrid power system by combining it with fuel cell to solve this problem.The hybrid power system with the characteristics of high energy density and high power density can both develop its advantages and avoid its disadvantages.Specially,the ulcapacitor can offer the peak power and recover the regenerative braking energy to assist the fuel cell power supply so as to save energy and improve the performance of the vehicle.In addition,which can also reduce the large current’s impact on the fuel cell,extend its service life and reduce the cost of the electric vehicles.In his paper,we mainly analyze the hybrid system of the electric vehicle.Our main research works include the selection of parameter matching,the topology and the energy management strategy to improve the performance of the vehicle.The article is described as follows:First of all,fuel cell(FC)with high energy density and ultracapacitor(SC)with high power density are selected as the power source by analyzing and comparing the relevant performance characteristics of main vehicle power sources.Then the topology selection,principle analysis and modeling of the hybrid system are carried out.Secondly,the DC/DC converter which is the core part of the power system of the electric vehicle is analyzed and designed.Through out comprehensive comparison and analysis,we adopt the Buck-Boost bidirectional converter with interleaving and parallel technology.And then,both the analysis of its model and the design of the parameter are studied.Thirdly,The energy management of the hybrid system is studied.This paper proposes a decentralized energy management strategy based on hybrid droop control.Consequently,It enables each power source to perform its own functions and improve the performance of the power system.What’s more,the detailed design process of above strategy is elaborate,mainly including the parameter design and the impedance analysis of the droop control voltage and current loop.Finally,Matlab / Simulink is used to simulate and test the vehicle hybrid system to verify whether the system has the characteristics of both high energy density and high power density,so as to reduce cost and improve performance of the vehicle.