Lightweight Design Of EV Brake System Based On Regenerative Braking

In the condition that petroleum source is to be scarce and air quality is deteriorating, EV(electric vehicle) which has great advantage of economizing energy and protecting environment has becoming the focus that big car manufacturers and research institutions develop. EV is regarded as one of ways that resolve the energy sources shortage and environment pollution problems. Regenerative braking is EV's great advantage over traditional cars. Kinetic energy in the course of braking can be transformed to electricity energy into battery by regenerative braking and can be utilized again when driving, so the vehicle's energy efficiency is improved. Now, how to coordinate and control the assignment proportion between friction brake and regenerative brake and recycle braking energy as more as possible given the precondition that brake security is ensured, has become one of regenerative braking system's key questions.Unlike traditional car's brake, EV's brake is completed by friction brake and regenerative brake collectively. Because motor's regenerative brake torque bears part of total brake torque demand, brake torque supposed to be supplied by traditional friction brake is reduced accordingly. Moreover, some of brake energy is transformed to electricity by generator, the request to brake bear hot load is reduced.So the size and mass of friction brake can be reduced.This paper firstly analyses car's brake energy in the city drive condition and shows the great potentiality of brake energy recycling. It introduces the working principle and basic structure of EV's regenerative braking system and analyses main factors that influence regenerative braking recycling energy.On the basis of researching the impact that front and rear brake force distribution makes on car brake stability in the traditional braking theory, this paper has established the model of brake force distribution during EV regenerative braking. Considering motor working character and battery's charge ability, this paper has established the model of motor mechanics and determines the maximum regenerative braking force that motor can supply. On the basis of theoretical analysis before, this paper comes up with regenerative braking control strategy which is based on ECE brake rules. The control strategy inclines to drive axle in brake force distribution and utilizes regenerative brake preferentially according to the maximum regenerative braking force that the motor can supply. It assigns proportions between friction brake and regenerative brake dynamically.Then, this paper has established the model of regenerative braking control strategy by ADVISOR software and did simulation experiment in NEDC and UDDS driving cycles, compared to ADVISOR built-in regenerative braking control strategy. The result shows that this paper's regenerative braking control strategy can bring motor's regenerative braking ability into play efficiently and performs better over ADVISOR regenerative braking control strategy in recycling braking energy.In the end, on the basis of caliper disc brake design theory, this paper has established its model. It did brake simulation experiment in certain driving cycle to determine performance demand to front disc brake of EV this paper researched. In the guide of disc brake design theory, it did lightweight design aiming at the car's previous front brake by Genetic Algorithm.