Study On The Mechanical And Electrical Braking System Of4WD Hybrid Electric Vehicle

From the birth of the vehicle, braking system has been played an important role insecurity. With the research and development of electric vehicles, braking system has beenchanged a lot. Hybrid vehicle’s braking torque includes motor regenerative torque andhydraulic torque. According to different driving conditions, the vehicle controller changesmotor’s conditions to achieve the best braking efficacy. Based on a four-wheel drive hybridelectric vehicle of a domestic car brand, the mechanical and electrical braking system is putforward, which includes hydraulic system and motor braking system. Then the optimumbraking energy recovery strategy is established aimed at recovering the braking energy asmost as possible in the condition of excellent vehicle security and stability. The researchcontent of this subject is as follows.Firstly, the mechanical and electrical braking system is put forward on the basis of afour-wheel drive hybrid electric vehicle, which can achieve the conversion of motor brakingmodel, mechanical and electrical braking model, and hydraulic braking model by increasingbrake pedal simulator and hydraulic control unit solenoid valves.Secondly, combined with ECE braking regulations, an optimum control strategy onbraking energy recovery is made on the basis of mechanical and electrical braking system,which can distribute the braking force to the motor shaft as much as possible while ensuringthe safety.Thirdly, establish the mechanical and electrical braking model system in AMESim,including the dual motor model, the battery model and the whole vehicle model. Then thecontrol model is made in Simulink based on finite state machine theory, which include thedriver intention module, the brake force distribution module, the parameter selection module,and AMESim/Simulink interface module. The co-simulation under several typical conditionsis carried out in AMESim/Simulink, and the results show the braking energy can be recoveredand the braking safety can be ensured.Finally, a braking system platform of the target vehicle is build, including the hardwarepart, the software part, real-time control platform and signal processing system. The real-time control platform includes ControlBase_VT and CANape, and the signal processing systemincludes solenoid valve driving circuit and pressure sensor circuit. The experiments itemsinclude the solenoid valve characteristics and pressure regulator characteristics, so thecharacteristics of the complex electromechanical braking system are verified preliminarily.