Design And Simulation Research On Regenerative Braking System Of Multi-Stage Series Composite Power Supply

In recent years,electric vehicles have become an important direction for the development of the automotive industry.However,due to the limitations of battery technology,the problem of the range of electric vehicles has always been the main problem that restricts the development of electric vehicles.Regenerative braking technology is a key technology to improve the driving range of automobiles.The super capacitor has the characteristics of fast charging speed and high power,and can be combined with the electric vehicle power battery to form a composite power supply system to improve the driving range of the electric vehicle.In the composite power supply system,the super capacitor is used as an energy storage device to recover stored braking energy,and as an auxiliary power supply to participate in the driving process of the auxiliary power battery to jointly drive the motor,to avoid the high power charging of the power battery and protecting the battery and extend its service life.Through the comparison of different topological structures,the passive series composite structure is taken as the main research direction,the regenerative braking system of electric vehicles is designed,and study the control of the recovered current.Based on the single-capacitor series composite power supply,the structure and control method are further optimized,a multistage adjustable series composite power supply system is designed,and an energy-constrained regenerative braking current control method is proposed to improve the recovery efficiency.On the MATLAB / Simulink platform,according to the structure designed in the paper,build a pure battery,a single capacitor and a double capacitor series battery----super capacitor composite power supply pure electric vehicle energy consumption model,enter the ECE city working speed model,record the cycle battery and super capacitor’s voltage,drive and braking current changes,calculate the energy consumption of the car under each model,and analyze the recovery efficiency and mileage contribution rate of the composite power system with different structures.Calculate the output duty cycle to control the working state of the rectifier bridge,simulate the braking process with different decelerations,analyze the braking current changes,and verify the feasibility of the control strategy.Analyze the requirements of the control system,design the controller of the brake recovery system,and introduce the composition,principle and function of each module.The regenerative braking experiment was carried out on a pure electric test car,mainly using a single capacitor series system as the object to carry out fixed duty cycle braking experiment and constant current braking experiment.The experiment uses 32 km / h as the initial braking speed,and the initial voltage of the super capacitor is set to 1 V.In the fixed duty cycle experiment,the braking signals with a duty cycle of 50%,70% and 100% are input respectively.In the current braking experiment,based on the system energy constraints,the real-time calculation of the output duty cycle control actual braking current is consistent with the given target braking current,verifying the feasibility of the control method.Build inertial test bench for series composite power drive experiment,including drive dynamics experiment and ECE cycle working condition experiment.Dynamic experiments show that the series composite power supply can effectively improve the starting acceleration of electric vehicles.At the same time,the addition of super capacitors reduces the energy output of the battery.Under ECE conditions,the battery output per kilometer is reduced by33.5 k J,which significantly improves the driving range of electric vehicles.