Research On Control Method Of Air Supply System For Vehicle Fuel Cells

In the past decades,the exhaust emissions of traditional gasoline and diesel vehicles have caused serious global pollution,so the global demand for zero-emission vehicles has increased dramatically.Among them,Hydrogen Fuel Cell(HFC)vehicles have gradually become a substitute for traditional gasoline and diesel vehicles due to their high efficiency,high power density and zero emissions.During the HFC operation,the control quality of the air supply system affects the overall output characteristics of the HFC.In the driving process of the car,various complicated working conditions are encountered.When the car faces these working conditions,it is particularly important to accurately control the air intake flow rate to meet the demand of the HFC output power of the whole vehicle.Therefore,the efficient control of the air supply system has become a hot research topic in the field of HFC.This thesis has done the following research on the efficient control of the air supply system:Based on the retrieval of many domestic and foreign literatures on HFC and its air supply system,this thesis summarizes the research status of HFC modeling and its air supply system control methods.According to the characteristics of HFC,a three-part simulation model of HFC voltage model,air supply system and fuel supply system was built.The basic principles of Model Predictive Control(MPC)are introduced,and the Quasi-infinite Horizon Model Predictive Control(QHMPC)is introduced in detail.Then based on the mathematical model,some solutions to the problem of difficult state observation are proposed.According to the scheme,a state quantity estimator is proposed.Then a QHMPC controller for the air compressor speed is proposed..Finally,by comparing the simulation with PI adjustment under the same conditions,it is verified that the QHMPC controller proposed in this thesis is superior to PI regulation in both dynamic and static characteristics.This thesis not only proposes the QHMPC control scheme for the HFC air supply system,but also develops and designs a matching controller for the extremely important part of the air supply system control-throttle control.According to the control requirements of the throttle,the corresponding controller hardware circuit is designed,which mainly includes the single-chip system circuit,CAN transceiver chip,related circuit and output circuit.Then a PID control algorithm for the throttle is proposed,and the underlying code configuration of the software and the design of the application layer program are made around the control algorithm,including the main modules such as initialization,main loop and timer interrupt function.Finally,the designed throttle controller is used to control the Bosch throttle.The experimental results show that the designed PID control algorithm has better dynamic response,as well as can respond to the change of the set opening quickly,and the static characteristics are better.The steady-state error is small,which can meet the requirements of steady-state error.