Research Of DC-DC Converter Topology For Fuel Cell Vehicles

With the environmental pollution and energy crisis becoming increasingly serious,Fuel Cell Vehicle has attracted more and more attention.However,drawbacks of the fuel cells,such as slow dynamic response andpoor adaptability to different working conditions,make it difficult for the fuel cells to meet the requirements of the vehicles.Therefore,it is necessary to introduce the DC-DC converter to achieve the goal of voltage decoupling and power control.In this paper,a novel Buck-Boost DC-DC converter topology is proposed by comparing with the traditional different Buck-Boost DC-DC converter topologies.A deep study on the proposed converter is conducted from several aspects including the working principles,the efficiency,the circuit model and the control methods.Firstly,a novel Buck-Boost DC-DC converter is proposed by analyzing different Buck-Boost DC-DC converter topologies of the pros and cons.Analysis of the circuit structure and components loss of the converter is made on this basis.Moreover,the working principles of the proposed converter under buck and boost mode are presented.Secondly,the small-signal model of the proposed converter is established by using the state space averaging method.Accordingly,the closed-loop control system for the converter is determined and the transfer function of the system is obtained.Because of the discontinuity during the mode transition and the disturbance of the input voltage,a series of compensation measures are put forward to improve the performance of the proposed converter.Thirdly,modeling and simulation on the proposed converter are carried out.The results show that the proposed converter has a steady output and the control method is suitable.With the compensation method,the performance of the proposed converter is improved.Lastly,an experimental platform with DSP digital control system is conducted.The results of the experiments are consistent with the theoretical analysis and simulation results,which means that the proposed converter meet the requirements of the industrial applilcations.The compensation method can improve the dynamic performance of the converter in practical applications.