| Affected by the energy crisis and environmental pollution,pure electric vehicle has become a hot spot for global automobile enterprises.As the core component of pure electric vehicle,the vehicle control unit controls the vehicle operation and is crucial to the vehicle’s power,economy,safety and comfort.Therefore,it is of great significance to increase the research and development of vehicle control unit for us to realize lane change and overtake,and to build the dream of automobile power.Based on the V-shaped development process,this paper explores the development of vehicle control unit.Taking a pure electric vehicle as the prototype,this paper mainly studied the following contents:(1) According to the functional requirements of the vehicle control unit,the MC9S12XEP100 chip was selected as the main control chip to design each module of the hardware circuit,and the PCB was painted and welded to obtain the vehicle control unit hardware.(2) Simulink was used to model the vehicle control unit application layer according to the overall architecture of the application layer.Firstly,the processing and filtering of digital signal,analog signal and CAN signal in the signal input module are described in detail.Then the starting mode,normal mode,power mode,economic mode,limping mode,astern mode and cruise mode in the pattern recognition module are designed in detail according to the driver’s driving habits under the premise of following the driving safety.The design of motor torque output in normal mode,power mode and economic mode fully considers the driver’s driving intention.According to the speed,accelerator pedal relative opening increment and SOC,the torque output of the motor is compensated by fuzzy control method.Aiming at the defects of traditional PID control and fuzzy PID control,this paper proposes an optimal design of cruise mode based on the combination of vehicle driving resistance and PID control.Finally,the function and realization of the signal output module are analyzed and explained.(3)According to the embedded programming specification,the clock module,I/O module,PIT module,ATD module and MSCAN module of the vehicle control unit basic software layer are designed.And the application layer and the basic software layer are integrated seamlessly.(4)The function of the basic software layer of vehicle control unit is verified by hardware in loop test.The vehicle control system model is built,and the vehicle dynamic performance,economy performance,starting mode,normal mode,power mode,economic mode,limping mode,astern mode and cruise mode in the driving control strategy are verified by forward simulation.After testing the function of the vehicle control unit can meet the expected design requirements. |
