Research On Battery Equalizer And Strategy Based On Bidirectional Flyback Converter

In recent years,with the rapid economic development,daily exhaustion of limited fossil energy and increasingly seriousness of environment pollution,the traditional oil-fueled automobile gradually retreat from people’s vision,while electromobile fueled by power battery has gradually aroused people’s attention.In order to satisfy power demands of electromobile,lots of battery monomers should be connected into battery pack which will be put into use,while the battery pack will go through the problems of inconsistency with some probabilities in the process of use so as to result in low service efficiency of the batteries,shorter life cycle and even potential safety hazards,equalization of batteries could be considered as one key technology which improves this problem of inconsistency,the research contents in this thesis carry out the research and related problems and design for the small-scale system of equilibrium targeting at equalization technology of batteries.This thesis analyzes the causes of the inconsistency related to power battery packs from production,use and storage,based on this foundation,we could be able to find out externally manifestation which could judge the energy imbalance of battery pack and carry out research towards balancing strategy of the large-scale battery pack in series under different imbalance situations in order to find the optimum strategy suitable for every bottom battery pack or the small-scale battery pack of the large-scale battery pack.Based on the precondition of balancing strategy,we combine comparison and analysis of existing balancing topology to put forward balancing topology based on multi-way bidirectional flyback converter so as to carry out simulation and verification of topology theory and function on the basis of comprehensively analyzing working principles of topology.As for balancing topology,this thesis designs the balancing system of battery pack with 12 monomers from the hardware and software,this system features principal and subordinate architecture and could be the management system of small-scale batteries with simplified functions in essence.In the hardware,the system is divided into four parts-master control module,monomer voltage gathering module,balancing control module and balancing execution module,every module centers on integrated components to finish their own functions and implement data exchange and order delivery through SPI communication protocol;in software,this system carries out the design of control algorithm on the basis of mean value method and writes communications program among equipment of master control and every subordinate module.Finally,this thesis chooses the battery pack of lithium iron phosphate with 12 monomers as the experimental objective to build up the experimental platform of balancing system,firstly the great efforts are made to verify the basic functions of balancing system,then to test the balancing effects of three kinds of typical imbalance situations,and finally to gather the experimental wave and data so as to carry comprehensive review for performances of balancing system.