Research And Design Of Grouping Equilibrium Scheme In Power Batteries

With the oil resource shortage and the fuel vehicle emissions are increasing, state and local governments pay more attention to the development of electric vehicles. The electric vehicle power battery is usually made by a large number of single lithium battery series and parallel connection, in the use of the process, due to the impact of battery production process and working environment and other factors, the performance between each single battery are inconsistent. This inconsistency may cause individual single battery over charge or over discharge, while will lead to the deterioration of battery performance speed, shorten the battery life, or cause accidents when severe cases. Therefore, the equilibrium control is particularly important in the charging and discharging stage.At first, this thesis analyses the cause and influence of inconsistent between the single battery. Then according to the evaluation of the consistency of the basis, this thesis gives two kinds of typical parameters, SOC and voltage, analyses their advantage and disadvantages and their using range. In the subsequent simulation part choose equilibrium strategy based on SOC, while in the experimental part choose equilibrium strategy based on voltage.The main works of this thesis are:A new type of grouping bidirectional equalization scheme which is based on the method of buck-boost converter and traditional multiple transformer has been designed, gives the circuit topology and control strategy, and the main parameters of the circuit is analyzed; According to the SOC parameter, build the equilibrium model under the environment of Matlab/simulink, charge and discharge simulation experiment is carried out, the result proves the theory feasibility of this scheme. Finally, Along with the construction of experimental platform, According to without equilibrium, with passive equilibrium and with grouping equilibrium, charging and discharging experiments for 12 single battery is carried out, the experimental results are compared and analyzed, and the results proves this scheme can obtain satisfactory experiment results in the battery charge and discharge.