Research And Design On The Regenerative Braking System Of The BLDCM For Electric Vehicle

Environmental pollution and energy shortage has become a prominent issue for global concern as the rapid growth of the number of cars in worldwide.Electric car is seen as the major alternative for fuel vehicles in the future because it has the advantages of low power consumption and zero pollution.However,the low energy density of the battery and the short driving range has become the key factors that hinder the deep development of electric vehicles.To solve the problem of short driving range electric cars is mainly achieved by regenerative braking energy,which takes the kinetic energy that reduced by the electric car convert into electrical energy via the power generation action and stored them into battery in the automobile braking process,which enhance the energy efficiency of electric car.At the same time here will generate a braking force,which improve the braking performance of electric vehicles.We make deep study to energy regenerative braking technology of Brushless DC Motor in order to improve the energy efficiency of electric vehicles and increase the driving range on a single charge.At first,we introduce the research status of electric cars and energy regenerative braking technology at home and abroad.Analyzing the advantages and disadvantages of various motor in the market,selecting a brushless DC motor as a model for this research,and according to the principle and basic structure of the Brushless DC motor establish its mathematical model.Then we make deep study for the working principle of Brushless DC motor's regenerative brake.Making analyze to circuit state during regenerative braking time of brushless DC motor in the half-bridge modulation control.And on this basis,we introduced the mathematical relationship between the regenerative braking electric current,counter electromotive force and the duty ratio in a PWM duty cycle.Making analyze to constraints and control strategy of electric car regenerative braking system.Finally,we selected the constant torque regenerative braking control as ourcontrol strategy.We designed a three-dimensional fuzzy controller based on the fuzzy control theory,and establishing a brushless DC motor regenerative braking system simulation model which took Fuzzy controller as the core.Making simulation in MATLAB / Simulink environment,the results show that the fuzzy constant torque control strategy we proposed achieve the desired effect on energy recovery and brake control.Finally,we completed the hardware circuit design of the brushless DC motor regenerative braking system based on the basis of DSP control,including the driving circuit design,the main circuit design,detection circuit design and the design of step-down circuit.Making software programming of the brushless DC motor regenerative braking system,using a modular design which enhanced the readability and general of the program.In this paper,we made experimentally verify to the brushless DC motor regenerative braking system based on DSP control,showing the experimental data and waveforms,and make analyze to the experimental results which verified the feasibility of the brushless DC motor regenerative braking system that we designed in this paper.