Research And Design Of Hydrogen Fuel Cell DC-DC Converter

In recent years,with the shortage of global oil resources,countries have gradually promoted the development of new energy industries.As the core component of hydrogen fuel cell vehicles,hydrogen fuel cell direct current(DC-DC)converter has gradually attracted extensive attention from researchers and has become a hot research topic in the field of new energy.This paper focuses on the circuit design and control theory of wide-range hydrogen fuel cell DC-DC converter,and develops a set of 2.8KW wide-range DC-DC prototype with good reliability.Firstly,this paper analyzes and compares the existing technical solutions of hydrogen fuel cell DC-DC converters,and gives the advantages and disadvantages of isolated and non-isolated topologies.According to the parameter design requirements of the hydrogen fuel cell DC-DC converter in this paper,it was decided to divide the circuit topology of the whole machine into a pre-boost circuit and a post-boost circuit,in which the pre-boost circuit is a two-phase interleaved parallel BOOST circuit,and the post-stage boost circuit is a full-bridge LLC circuit,and the working principle of the power topology of the circuit at all levels is analyzed and the parameters of key devices are designed and selected,which provides a theoretical basis for the construction of prototype hardware circuits.Then,two sets of loop control units,digital-analog op amp circuit and pure digital control chip circuit,are designed,and simulation experiments are carried out using PSIM simulation software,and the relevant simulation waveforms and control codes are given.Through the analysis of the simulation verification results,the rationality and reliability of the designed circuit parameters are proved.Then,the research results of DC-DC converter filtering algorithm,power lithium battery equalization charging algorithm,and current control algorithm of multiphase interleaved parallel circuit are introduced in detail,and the comparative experimental results of current control algorithm and traditional current sharing control algorithm of multiphase interleaved parallel circuit are given,which further improves the safety and stability of the system.Subsequently,this paper introduces the hardware circuit of the prototype in detail,and combines the control strategy of the lithium system of hydrogen fuel cell vehicle power to give a closed-loop control scheme of the two-phase interleaved parallel BOOST circuit of the front stage and the full-bridge LLC circuit of the rear stage.Among them,the two-phase interleaved parallel BOOST circuit of the front stage adopts the control mode of constant voltage and constant current double-loop competition,and the full-bridge LLC circuit of the rear stage adopts the control mode of open loop or constant voltage.The C2000 series DSP microprocessor TMS320F280049 automotive-grade special digital control chip provided by TI is selected,which realizes the all-digital control mode of the two-stage circuit of the whole machine,effectively improves the anti-interference ability of the system,and further improves the safety and reliability of the system.Then,the final experimental results of the prototype are given,including the efficiency curve of the whole machine and the key signal waveform of the prototype.Finally,the experimental results show that the prototype meets the design indicators of wide output voltage range,high step-up ratio,low output ripple and high power,and the whole machine has CAN communication,output voltage soft start,complete fault detection function and control logic.Under the condition of 2.8KW full load,the conversion efficiency of the whole machine reaches 94.5%.The working waveform of the key signal of the whole machine is consistent with the theoretical analysis and simulation results.The correctness,rationality and effectiveness of hardware circuit design,key device parameters,PCB layout and control schemes are fully verified.