Study On Brake Pedal Stroke Simulator And Control Strategy For Hybrid Electric Car

With the increasing number of automobiles, environment and energy face greatchallenge. Energy conservation and environmental protection have become people’s pursuitof the goal and many big car companies, universities and institutes are researching in thisarea. Developing new energy vehicles is an effective way to solve this problem and hybridelectric vehicle is one kind of new energy vehicles. Regenerative braking system thatconverts the kinetic energy when a vehicle brakes into electric energy and reserves it is acore technology of hybrid electric vehicle. It can realize the energy recovery, increase thedriving range and make the vehicle decelerate.Developing regenerative braking system not only involves the research of controlstrategy, but also involves the design of hardware. Braking pedal stroke simulator is onemajor component to realize this function, can give a good pedal feel to the driver, increasethe energy recovery rate and ensure the braking safety.The research object of this thesis is one hybrid electric car and the main content is thedesign of a key component, brake pedal stroke simulator, in regenerative braking system.The structure and the key parameters of the brake pedal stroke simulator are determined, thefunction of regenerative braking system is realized and the brake pedal feeling is ensured.The main contents of this thesis are as follows:1. The need of the braking control system is analized. The software and hardwarescheme of braking control system are designed and the control strategy of the brakingcontrol system is proposed. The control strategy of the braking control system includes theidentification of the braking intent, the theory of the braking force distribution and thecontrol of the magnetic valves and the motor hydraulic pump.2. The research of the traditional braking control system is done. Doing thecharacteristic experiments of the braking catanator on the ESC/RBS(Electronic StabiityControl System/Regenerative Braking System) integrated test bench. The relation curves ofthe braking pedal force&pedal stroke, the master cylinder pressure&pedal stroke and thepedal force&the master cylinder pressure are obtained. The quantization of the brakingfeeling is made, the traditional braking system model is constructed and parameterization ofthe braking system components is made. These are the basics of designing the braking pedalstroke simulator.3. Introduction to the function of the brake pedal stroke simulator is made. According to the P_V characteristic of the hydraulic braking system, the structure of the brake pedalstroke simulator is determined and the key designing parameters are calculated. TheAMESim model of the brake pedal stroke simulator is constructed and the selection for thecontrol valves of the brake pedal stroke simulator is introduced.4.The braking control system with brake pedal stroke simulator model and thetraditional braking system model are constructed. Through simulation analysis, the brakingperformance need is met, the braking energy recovery rate can increase approximately by30%, the brake feeling and the traditional brake feeling are generally consistent, and thefeasibility of the hardware and software scheme of the braking control system is proved.