| Due to the limitations of current battery technology,the battery will attenuate under frequent high current charging and discharging,which will affect the service life and shorten the cruising range of electric vehicles.Regenerative braking is an important technology to extend the cruising range of electric vehicles,and the composite power supply system can reduce the charge and discharge current of the battery to protect the battery and slow its attenuation.Therefore,this article takes a rear-axle drive commercial EV as the research object,and conducts researches on regenerative braking and composite power technology.The following researches are shown:(1)The structural composition and working principle of the regenerative braking system is analyzed,the the series regenerative braking system is selected as the object,and the impact of energy storage system,motor performance,regulations and working condition constraints and other influencing factors on braking energy recovery are analyzed.(2)The composite power supply system is designed by analyzing the characteristics of various components,the battery-supercapacitor composite power supply combination is determined,also the active configuration of super capacitor series DC/DC is selected,and its working mode is analyzed;the parameter matching and selection of batteries and supercapacitors are carried out.(3)Research on the energy management control strategy of the commercial EV is carried out.Firstly,the front and rear wheel braking force distribution curves were formulated,and the rear axle electro-hydraulic braking force distribution strategy was established using the fuzzy control algorithm.Secondly,the research on the power distribution strategy of composite power supply is studied,and a logic threshold composite power distribution strategy is formulated,and a compound power distribution strategy based on fuzzy control is proposed.(4)CRUISE and Simulink are used to build a vehicle and energy management control strategy joint simulation platform.Firstly,the braking energy recovery control strategy is simulated based on cycle conditions(NEDC,WLTC and C-WTVC),and an experiment is carried out using a real vehicle equipped with the original strategy.The results indicate that in this paper,the braking energy recovery control strategy can recover braking energy effectively,which is better than the original vehicle’s own recovery strategy.Secondly,the power distribution strategy of the composite power supply is simulated in dynamic and cycle conditions(NEDC and WLTC),the results proves the rationality of the parameter matching of the composite power supply.The proposed composite power distribution strategy can reduce the high current of the battery.Compared with the logic threshold strategy,the reduction of the high current is reasonable and the effect is better.(5)In order to further improve the effect of fuzzy control,the adaptive neural network and particle swarm algorithm are used to optimize the braking energy recovery control strategy and the composite power distribution strategy.In NEDC and WLTC operating conditions,the optimized strategy is analyzed by joint simulation analysis.According to the results,the effective energy recovery rate after optimization is respectively increased by 2.84% and 3.60%.The optimized composite power distribution strategy can reduce the maximum current of the battery by 20 A and 26.1A compared to before optimization. |
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