Research On The Key Technology Of Regenerative Braking In Electric Vehicle

With the development of modern automobile industry,the automobile has made a great contribution to meet the needs of people's daily life.Due to a large number of car ownership and fast growth,the energy crisis and environment problem have become the two major problems the world facing today,therefore,it has become an important direction to research electric vehicle in the world.The electric vehicle,whose main power source is battery,is driven by the motor.It has the advantages of zero emissions,high efficiency,low noise,and so on.The research of electric vehicle is the key to promote the implementation of the new energy vehicle strategy and achieve our country's strategic goal of “corner overtaking” in the automotive industry.After the test of electric logistics vehicle,we found that the electric logistics vehicle's safety and stability are affected by the introduction of regenerative braking,and the efficiency of braking energy recovery is not ideal.In order to solve this problem,the factors which can affect the braking safety of electric vehicle and the efficiency of braking energy recovery are analyzed.Then the key technological points of regenerative braking are put forward,and the control strategy whose purpose is recycling the braking energy as much as possible on the premise of ensuring the safety and stability of braking is put forward.The main works of this paper are as follows:Through the analysis,the opening of brake pedal,its change rate and current speed as the braking intention recognition parameters are selected,and the classification of the braking mode is made.Then,the fuzzy recognition of driver's braking intention system is built.Based on the analysis of the existing typical regenerative braking control strategy,the regenerative braking control strategy is put forward according to the different results of driver's braking intention.In the strategy,the braking force distribution between the front axle and rear axle is mainly based on the ideal curve of braking force,and the distribution between friction braking force and regenerative braking force is relying mainly on fuzzy controller to achieve,whose inputs are motor status,battery status and braking state.Taking the vehicle simulation software ADVISOR as the platform,the whole vehicle model,relevant vehicle parts model and the regenerative braking control strategy model are built.In the custom condition and typical working conditions,on the point of view of vehicle braking stability and safety and braking energy recovery efficiency,the control strategy is verified.And the custom condition is built on verifying the feasibility of braking intention identification.The results show that this method can recover the braking energy effectively under the premise of ensuring the stability and security of the braking system.The DSP28335 chip is chosen as the main control chip,and the hardware circuit and software of the controller are designed.Among them,in the hardware,the minimum system circuit,JTAG interface circuit,serial communication interface circuit,sampling circuit and drive circuit are designed;In the software design,the idea of hierarchical design and modular design is used to design the main program.Among them,the signal sampling program,the interrupt processing program,the braking intention recognition program and the regenerative braking control program are designed.