Study On Vehicle Hybrid Power Energy Management System

Exhaust emission from traditional oil-fueled vehicles is one of the major sources of atmospheric pollution,and fossil fuels are becoming increasingly scarce,so it is necessary to develop zero-emission pure electric vehicles.Power batteries are the main energy storage components of electric vehicles,but due to the current technological level,the power performance of electric vehicles is not particularly satisfactory.Supercapacitors have the advantages of high power-density,fast charging and discharging speed,and long cycle life.Connecting them in parallel with the power battery pack to form a hybrid power supply can complement some of the existing problems of electric vehicles.Based on this,an energy management system is designed so that the hybrid power system can not only meet the vehicle's power requirements,but also extend the cycle life of the power battery to reduce the cost of the vehicle.Firstly,the Toyota Prius is transformed into an electric vehicle,the motor parameters,hybrid power parameters and topology of the vehicle are matched,and a model of the pure electric vehicle is established in the ADVISOR simulation software.After that,a logic threshold control method is designed to manage the energy of composite power source,and the feasibility of this method is verified by simulation.Compared with the independent power source,it is found that the hybrid power source can indeed reduce the power fluctuation of the power battery.In order to further optimize power allocation,a dynamic programming algorithm is used in this paper.After inference,the square sum of the battery output current is used as the objective function.Dynamic programming as a global optimization algorithm cannot control the energy management system in real time,but it can be used to guide fuzzy control.Simulation results show that the fuzzy control obtained by this method is better than the logic threshold control.This paper adopts a segmented design idea to divide the energy management system into a scalable hardware layer,a middle control layer,and an upper energy distribution layer.The bottom layer adopts dual-phase conversion DC/DC converters to reduce bus current and voltage ripple and generate power density;the middle layer uses decoupling control for dual-phase conversion DC/DC converters,and improves the dynamic response speed of super capacitor power by model prediction control;the upper layer adopts fuzzy control rules guided by a dynamic programming algorithm for energy distribution management.In order to verify the feasibility of the energy management system,an experimental platform with a rated power of 1.5k W is designed.The experimental results show that the composite power supply can effectively reduce the output power fluctuation of the power battery pack and increase the life of the power supply system.