Research On Equilibrium System Of Electric Vehicle Battery Pack

In pure electric vehicles,the series and parallel power battery was often used to provide energy.Due to the battery production process and the impact of the working environment,the battery pack will be inconsistent,and the inconsistency will cause the reduce of the battery using performance,reduce the battery capacity and service life,and then shorten driving range of the pure electric vehicles.As a module of the battery management system,The equalization module played an important role in reducing the difference between the single cells and improving the effective energy of the battery pack.This article relied on the new energy vehicle collaborative innovation comprehensive service platform and China Power Valley innovation entrepreneurship development project,carried out electric vehicle power battery balance management system technology research.The article,studied the cell inconsistency on the electric vehicle power battery by a combination of simulation and experiment,achieved a simple and efficient hybrid battery balance management system.The main research work includes the following several aspects.(1)The paper analyzed the inconsistency of the lithium battery pack,and the inconsistency was mainly performanced in the capacity,the resistance and the voltage.For the selection of the equilibrium variable,introducted different equilibrium variables.Taken different equilibrium variables according to the different states.(2)The advantages and disadvantages of various balanced topologies were analyzed and compared.Considering the efficiency of equalization,the difficulty of circuit control and the loss of each switch,the topology of the dissipative resistance equalization circuit and the flyback equalizer circuit was selected.Builded a balanced simulation model in the Matlab platform,according to the different size of the battery capacity to take different balanced topology.(3)The simulation verification was implemented in the charge,discharge,standing state respectively.the use of balanced circuits and strategies could achieve rapid balance of the battery pack.Implementation.(4)The LTC6804,which uses the passive equalization function,was used as the voltage acquisition chip and the LTC3300 was choosed as the active equalization control chip,and the hardware and software design of the equalization module was completed.Under the bench test during the charge and discharge,the designed balance module has a certain balance effect,improved the batterygroup inconsistency.