Design And FMEA Research On Vehicle Control Unit Of Electric Vehicle

As the energy consumption and environmental pollution is becoming worse, PureElectric Vehicles is one of the direction of the development of vehicles in the future.This paper takes the Vehicle Control Unit(VCU) as the research object. It mainly studysthe hardware redundancy design of the Vehicle Control Unit, Failure Mode and ErrorAnalysis(FMEA) of hardware circuit of Vehicle Control Unit, design of communicationprotocol between the master microprogrammed control unit(MCU) and slavemicroprogrammed control unit of Vehicle Control Unit and the hill-start control of PureElectric Vehicle.While designing the Vehicle Control Unit, the function of each module areanalysed which include signal acquisition module, the drive module, CAN transceivermodule and MCU module. In order to improve the reliability and security levels, ittakes redundancy design for the key signal and circuit of Vehicle Control Unit whichinclude the brake pedal signal, vacuum booster pump pressure signal and theMicroprogrammed Control Unit etc. Finally, hardware redundancy schematic designand the drawing of PCB are finished.In the hardware design process, it has an important effect on improving the reliabilityof the Vehicle Control Unit to make the the FMEA. It analyzes device the failure mode,failure mechansim, the influence on the VCU for each failure mode. And then for thepotential damage, effect measures can be taken to improve the reliability of the VCU.For the communication between the dual MCU of the VCU, the paper firstly makesa brief introduction that how the Serial Peripheral Interface(SPI) communicate. For thereason that SPI does not provide the response mechanism, the paper design thecommunication protocol for the communication between dual MCU which includemessage format, data content and the size of buffer. Then communication functions aredesigned.To be aimed at some problems brought about by the Hill-start for pure electric vehicle, in order to control the vehicle start up smoothly according to the expectedspeed curve when the vehicle starting on slope road, in this paper the authors analyzedthe longitudinal vehicle dynamics and wheel dynamics firstly, then build a simplenonlinear vehicle model. After verificating the correctness of the model by the aid ofveDYNA, a comprehensive software for the efficient simulation of vehicle dynamics,the authors designed a controller using Sliding Mode Variable StructureControl(SMVSC). And the simulations for different slope conditions are carried outbased on the veDYNA. The results show that the sliding mode controller has a goodcontrol performance.