Research On Vehicle Controller And Control Strategy Of Pure Electric Vehicle

Automobile not only facilitates our life,but also brings increasingly severe energy crisis and environmental problems.Nowadays,with the advantages of zero emission,low noise and high energy efficiency,pure electric vehicles(PEV)are gradually occupying an increasingly important position in the automotive field.The vehicle control unit(VCU)is the driving brain of the pure electric vehicle.It analyzes the driver's intention and formulates the control strategy by collecting the operating instructions sent by the driver and vehicle status information,and then sends the control instructions to each electronic control unit(ECU)through CAN bus to coordinate all parts of the vehicle in order to ensure the normal and stable driving of the vehicle.In this dissertation,the VCU of PEV is taken as the research object.This dissertation introduces the research status of PEV and the VCU at home and abroad,analysis of the vehicle control system composition and working principle,formulates the basic parameters and performance indicators of the vehicle to design the main components of the vehicle power system.Study the working principle of CAN bus and design the vehicle communication network.Based on fuzzy control,the driving control strategy of the whole vehicle is formulated,the simulation model structure of the whole vehicle is designed by forward simulation method,and the models of main components of PEV are built based on Matlab/Simulink.After integrating the models of each component,the whole model is simulated to verify whether the parameter matching of the power system is reasonable,whether the vehicle performance can meet the established performance index requirements and whether the driving control strategy is effective.This dissertation analyzes the basic functions and design requirements of the VCU,designs the hardware architecture and software architecture of the VCU,and then designs the hardware and software of the VCU with the modular design idea.The hardware design includes: main control chip selection,minimum system design,signal processing module design,communication module design and driver module design.Software design includes: main program design,power on initialization subroutine design,system self check subroutine design,fault processing subroutine design,data acquisition subroutine design,can bus message receiving and sending subroutine design,working condition judgment and pattern recognition subroutine design and 485 serial communication subroutine design.The automatic code generation technology is adopted to generate the management code,and then the code is integrated with the manually written execution level and interface level code to complete the coding of the VCU.In order to verify whether the designed VCU is reasonable and test the performance of the VCU,each hardware unit module in the designed VCU is debugged.In the end,the whole vehicle test experiment platform is built to simulate the main components of the whole vehicle for integrated debugging,to verify the reliability of the whole VCU hardware and software design and the effectiveness of the vehicle drive control strategy.