High Efficiency Wide Input-voltage Range Boost Three-level DC-DC Converter For Fuel Cell Vehicles

With the rapid development of the automobile industry,the number of cars in the world continues to rise,the automobile has become an indispensable means of transport in people's lives.While the number of automobile is increasing,demands for fossil resources are also growing rapidly.The vehicle exhaust pollution to the environment is getting worse.As a major component of electric vehicles,fuel cell needs for DC voltage boost converter to raise to its rated voltage and so that it can drive the motor in an automobile.It is of great significance to do research of DC boost converter with high reliability,wide gain and high efficiency to the development of electric vehicles fed by fuel cell.In this paper,several common vehicle-mounted DC-DC converter topologies are discussed,and the problems are analyzed afterwards.A novel quasi-Z-source three-level Boost DC-DC converter is proposed to meet the requirements of wide voltage input range,fast response of steady-state output voltage and high energy conversion efficiency of fuel cell.The converter has two possible modulation strategies,interleaving modulation and phase shifting.The characteristics of the converter are analyzed under two modulation strategies,better operation characteristics of the converter are achieved under interleaving modulation strategy.The converter operates under the interleaved modulation strategy with the advantages of wide voltage gain range,small voltage stress of the switching tube and double frequency of the inductor current.In addition,MOSFET is adopted instead of a diode for larger RMS current.With the introduction of synchronous rectification technology,zero-voltage switch of MOSFET is achieved.The efficiency of converter can be improved to a certain extent.The parameters of the new converter are designed,the simulation model of the converter is built with MATLAB software,and the working principle and steady state performance of the converter are analyzed by using the simulation model.At last,an experimental prototype with 40 V ~ 150 V input,400 V output voltage and 1200 W output power is built in the laboratory.The experimental results verify the correctness of the theoretical analysis.