Research On Control Strategy Of Electric Vehicle Hybrid Energy Storage System

At the moment when the energy crisis and environmental pollution are becoming more and more serious,electric vehicles are favored because of their advantages such as energy saving,environmental protection,and low pollution.Energy storage technology is the key to the development of the electric vehicle industry.At present,electric vehicles mostly use batteries as a single energy storage power source.Due to the low power density of power batteries,performance limitations such as high current charge and discharge cannot be met,and the power requirements of electric vehicles in actual working conditions cannot be met,limiting the development of electric vehicle technology.Therefore,the hybrid energy storage system combining high energy density devices and high power density devices has attracted widespread attention in the industry.This article focuses on the operating characteristics of electric vehicles and the operating characteristics of hybrid energy storage systems,and conducts the following research from the perspective of energy and power requirements:First of all,this paper summarizes the current research status at home and abroad based on the energy management control of hybrid electric vehicles.The development status and shortcomings of electric vehicles are introduced,and the characteristics of common energy storage components in the current market are analyzed in detail.By comparing and analyzing the characteristics of different energy storage components,super capacitors and batteries are selected as energy storage units for electric vehicles,and two types of energy storage are established.The respective equivalent circuits of the unit perform quantitative analysis on the charge and discharge characteristics of the two energy storage elements to provide a theoretical basis for the study of control strategies.The structural characteristics and application scenarios of inactive,semi-active and fully active topological circuits are discussed.The active topology is used as the main energy management circuit of the hybrid energy storage battery and supercapacitor energy storage system;the working principle of the bidirectional DC / DC converter is analyzed in detail,the main circuit parameter design is completed,and the mathematical model and transfer function are derived.Then,combining the load power demand and change characteristics ofelectric vehicles,an energy management and distribution control strategy for a hybrid battery and supercapacitor hybrid energy storage system is proposed.SOC is used as the basis for the energy layer transfer.The open circuit voltage method and the ampere-hour integration method are used for SOC.According to the threshold value of the motor’s required power and the SOC estimation of the energy storage element,a logic rule control strategy was designed to cooperate with the energy storage element.Among them,in order to reduce the number of high-current discharges of the battery,a battery was added to the super capacitor and the motor The power supply mode increases the number of supercapacitors used;completes the design of bidirectional DC / DC controllers by establishing a small signal model to achieve power distribution and balance of the energy storage system;designed an automatic adjustment controller to make the power distribution of the energy storage system faster Follow the power requirements of the motor;use MATLAB / simulink software to build a simulation model of the hybrid storage battery and supercapacitor energy storage system,and complete the simulation of the acceleration or deceleration of the motor in the buck mode of the energy storage system.The simulation results verify the feasibility of the control strategy.Finally,based on the theoretical analysis and simulation results,an experimental prototype model is built,and the basic working mode and specific working conditions of a hybrid energy storage system composed of a battery pack,a super capacitor bank,and a bidirectional DC / DC converter are experimentally studied.The stability of the high-side voltage under each model was verified,and the correctness of the theoretical analysis and simulation results was proved.