Electric Vehicle Passive Series Hybrid Energy Storage Structure And Research

New energy vehicles is the direction of the development of the automotive industry currently,which electric vehicles is the focus of the automotive industry in recent years.But at the present stage,the energy density of the battery is low?the cost is high and the driving range is short after charging,so that the development and popularization of the electric vehicle has been severely restricted.Regenerative braking technology can be used to recycle the braking energy and drive the vehicle,which is one of the effective ways to improve the electric vehicle driving range.On the basis of the way that the battery is used as regenerative braking energy storage device,the super capacitor is added to form the battery-super capacitor power supply system,the main purpose is to make use of the super capacitor of high power,high efficiency and long life characteristics to improve the working conditions of the battery.Composed of battery and super capacitor hybrid energy storage system of a miniature pure electric vehicle as the research object,research battery and super capacitor passive series regenerative braking system structure and braking current control strategy.First of all,starting from the electric vehicle energy demand,analysis the main components characteristics of the regenerative braking system and choose the suitable type,and then based on the comparative analysis of compound power supply structure,select battery and super capacitor passive series structure,form hybrid energy storage regenerative braking system and then make a detailed analysis of the overall structure,basic function and working principle.Secondly,build a regenerative braking system model in the MATLAB/Simulink environment,mainly by battery module,super capacitor module,rectifier module,brushless DC motor module and controller module,and each basic module has been validated by comparing the simulation and experiment,and the simulation result is good;In addition,starting from the main circuit mathematical model and experimental data of regenerative braking system,through the MATLAB programming tool for the simulation of regenerative braking system,analysis the simulation result of the regenerative braking current in the condition of different duty cycle.The simulation results show that two models can be used to recycle the braking energy and store it in the super capacitor.Then,select constant braking current control strategy in consider of the factors of safety performance,energy saving and braking feeling,respectively using the control strategy based on duty cycle control rule and fuzzy control to achieve a constant braking current of regenerative braking system,analysis the effect of recovery rate under the condition of different target constant current value during regenerative braking process,by comparing the simulation results,the constant current control strategy based on fuzzy control have a higher recovery rate than the constant current control strategy based on duty cycle control rule in the same target current.Finally,the hardware circuit,the main program of lower computer and the software of upper computer are introduced.Based on the test vehicle conduct fixed duty cycle regenerative braking open loop test,the feasibility of regenerative braking system is verified;Apply control strategy based on duty cycle control rule to the main program of the lower computer,and conduct constant braking current of 50 A and 70 A regenerative braking test respectively,energy recovery rate is 15.13% and 20.97%.The validity and rationality of the constant current control strategy of regenerative braking system have been proved.