Research On A Novel Dual-Boost Step-up Converter For Fuel Cell Vehicles

With the rapid decline of non-renewable energy storage,people's research goals have gradually turned to the field of fuel cell vehicles.However,fuel cell output voltage fluctuates greatly and the voltage level is low,which makes it difficult to meet the requirements of fuel cell vehicles for power sources.Therefore,a DC/DC converter that can achieve functions such as Boosting voltage levels and voltage decoupling is a necessary part of the system.Based on the requirements of fuel cell systems for DC/DC converters,this paper proposes a new Dual-Boost Step-up Converter and compares it with several converters.In addition,the related research work is carried out from the working principle,circuit model and control method of the converter.Firstly,classify and summarize the existing DC/DC converter structures,specifically divided into isolated and non-isolated structures.The number of devices,type selection,voltage stress and Boost ratio of the new Dual-Boost Step-up converter are compared with several typical Boost converters.Based on the analysis of its working principle,the corresponding state equations of the converter under different working states are obtained.Secondly,a small-signal model of the converter under different operating states is established according to the state space averaging method,and the transfer function is obtained by Laplace transforming the model.A closed-loop controller based on single feedback of output voltage and dual feedback of inductor current and output voltage is designed.In addition,to solve the problem of soft output characteristics of fuel cell,a feed-forward double closed-loop controller for input voltage fluctuation is designed to ensure the stability of system output.Then,the hardware and software of the new Dual-Boost Step-up Converter system are designed.According to the corresponding indicators of the designed power module,the parameter values of components such as capacitors and inductors are calculated and the device selection is performed.In addition,the drive circuit of photoelectric isolation is designed with TLP350 as the core.In addition,according to the needs of the controller,the voltage detection circuit is designed with linear optocoupler as the core,the current detection circuit with Hall sensor as the core and the auxiliary power circuit with power module.At the same time,a PI control program based on DSP system was written.Finally,the simulation model of a new Dual-Boost Step-up Converter system was established in Matlab/Simulink environment,which verified the effectiveness of the proposed converter and controller.In addition,the prototype of the proposed converter is built,and the subsequent prototype debugging,Boost ratio of the converter,efficiency of the system and robustness of the system were carried out.Experimental results show that the proposed new Dual-Boost Step-up Converter can meet the requirements of fuel cell vehicles for high Boost ratio,high efficiency,and good robustness of DC/DC converters.