Study On Staged Active Equilibrium Control Of Electric Vehicle Power Battery

As the power source of pure electric vehicle,the development of technology will determine the development of electric vehicle industry.As the electric vehicle requires a large battery current output in the use of the process,and sometimes the electric vehicle will also cause deceleration of voltage and current changes by frequent acceleration.At present,the battery can't meet the requirements of the electric vehicle output standards,which requires the electric vehicle battery must be composed of dozens or even hundreds of battery monomer.Due to the battery production technology,the cell parameters are inconsistent,and the battery will appear excessive discharge and other issues in use process,to further deepen the extent of the inconsistency caused by the battery,the internal structure of the power battery damage,which shorten the service life of the battery and increase battery cost.In order to reduce the problem that caused by the use of the battery,it is necessary to control the use of the battery in the process,which lead to the emergence of equalization control technology.The equalization control technology can prevent the battery from charging and discharging to a certain extent,and ensure the performance of the battery is in a consistent state,which is helpful to improve the service life of the battery.At present,the domestic and foreign common equalization technology display in the balanced control strategy and the balanced circuit.The core problem of balanced control strategy like this way: finds a suitable variables for equilibrium control of the battery,keeping the selected variables being consistent,to complete balance control of battery.The equalization circuit consists of energy dissipation and energy dissipation type.And the energy dissipation type is currently a hot research,and mainly concentrated on the structure of capacitor and transformer type.In this paper,through the design of the SOC estimation algorithm and the equalization control design of the lithium battery,the dynamic phase equilibrium control of the lithium ion battery are completed.Specific work as follows:(1)This paper analyzes the performance characteristics of the common power battery and the reaction form of the lithium ion battery.And introduces the advantages and disadvantages of the common battery model to decide the collection of battery model.Analysis of the reliability of the battery group process,the reliability of the battery connection method proposed in this paper is verified.(2)Analysis of the influence of battery SOC estimation of some common factors and battery SOC estimation algorithm,proposed correction algorithm and extended current time integral method based on Kalman algorithm,the establishment of power lithium ion battery simulation model for correction algorithm set different conditions for simulation.Aiming at the improved correction algorithm the SOC phase estimation the charging stage and the hybrid phase SOC are estimated respectively.By comparing the simulation results of the modified algorithm with the traditional algorithm,the error estimation algorithm proposed in this paper can be kept between 1.2% and 4.2% and the overall estimation error is small which satisfies the requirement of battery SOC estimation accuracy.(3)The analysis of advantages and disadvantages of current variables and the existing equilibrium method,which determine the variables of this paper.The limiting equilibrium and mixed equilibrium control strategy to be proposed.The simulation model of power lithium ion equalization control is established and the proposed method is carried out in the pure discharge condition and the complicated condition simulation experiment.The simulation results show that the equalization strategy can complete the battery equalization control well.(4)The design of the parameter acquisition module of the main control circuit board the equalization control board and the battery is carried out and the corresponding equalization control software design is completed.(5)The circuit board and the system software have been completed and the experimental facilities are made.After the physical circuit board is built the hardware inloop simulation experiment is carried out by dSPACE to complete the physical test.Through the analysis of the results the feasibility of the equilibrium system proposed in this paper is verified.