Research On Regenerative Braking Of EV And Power Distribution Strategy Of Composite Power Supply

Electric vehicles do not rely on fossil energy and have little impact on the environment,so they have been promoted with good market prospects.However,due to the short driving mileage,low specific power of batteries and ineffective peak power for vehicles,high current discharge will lead to a serious decline in its performance,which restricts the further development of electric vehicles.Regenerative braking of motor will recover part of braking energy,effectively improve energy utilization and extend vehicle driving mileage.Compound power supply system can make up for the shortcomings of single batteries with poor instantaneous high current charging and discharging ability,and improve the performance of vehicle power system.On the basis of electric motor operation,the state of power transistor conduction and energy flow during motor braking feedback under half-bridge and full-bridge chopper modulation modes is analyzed in depth.The regenerative braking of the motor is realized by using half-bridge chopper modulation and constant torque feedback fuzzy control strategy.The structure and working mode of the vehicle-mounted composite power system are analyzed.Aiming at the problem of how to distribute the required power reasonably between two kinds of energy sources,the working characteristics of storage battery and supercapacitor and the power distribution strategy of compound power supply are analyzed,and an improved fuzzy control method of power distribution is adopted.In the Simulink environment,the simulation model of the motor regenerative braking system is established.The simulation proves that the half-bridge chopping modulation method and the constant torque fuzzy control can effectively realize the braking feedback.Using ADVISOR vehicle simulation software,based on the Toyota Prius model parameters andi the original EV model,the secondary development of the composite power supply system is carried out.Under the new European cycle test conditions,the simulation results show that the improved control strategy can not only effectively improve the energy feedback efficiency,increase the vehicle mileage,but also improve the vehicle power performance.According to the functional requirements of the control system,the hardware circuit and software program are designed.The software structure of the controller adopts the way of"main program circulation + interruption,,to realize the regenerative braking of the experimental vehicle.The braking system of the experimental vehicle is developed,and the monitoring platform of Lab VIEW upper computer is developed,which provides the driver with the reference information of the control system of the experimental vehicle.Aiming at the problems of data loss and not timely unpacking processing due to large amount of data transmission and high speed requirements during communication,a communication method for parallel processing of data received by the host computer is proposed.Finally,the rationality of the design is verified by the test of the experimental vehicle,which lays a foundation for the follow-up study of the braking system of electric vehicle.