Design Of Lithium Battery Management System

As the power sources of electric vehicle, the quality of performance of power batterysystem has a decisive influence on the performance of the electric vehicle. Due to thebattery management system plays an important role in the area of ensuring the safety ofbattery and improving the battery life, the research to it has very realistic significance.Combining with the principle and the performance parameters of lithium battery, thisthesis analyzed the influence of the external environment to the performance of lithiumbattery. And during this, this thesis is focus on the introduction of changes of lithiumbattery internal chemical mechanism caused by abuse and the consequence of which. Thenthis thesis mainly studied the key technologies of the charge of state estimation, the stateof healthy estimation and the strategy of balance management, etc. In the part of the stateof charge estimation, this thesis analyzed the problems of the traditional definition of thestate of charge and proposed a new definition based on the maximum available capacityand the maximum dischargeable capacity. Based on the definition, in combination with theCoulomb counting method, the open circuit voltage method and the dc resistance method,this thesis designed a new method for the state of charge estimation. In the part of balancemanagement strategy, this thesis analyzed the problems of the traditional batteryconsistency evaluation method and discussed the advantage of the consistency evaluationmethod based on the capacity utilization ratio. On this basis, this thesis proposed a balancesolution based on the capacity utilization ratio. On the basis of theoretical analysis, thisthesis designed the software and hardware of an actual lithium battery managementsystem. In hardware, this thesis designed the hardware circuits of the voltage andtemperature detection module, balance module, current detection module and mastermodule. In software, this thesis designed the software for the various hardware modulesand the PC-side monitoring software.In this thesis, the research of lithium battery management system is based onelectrochemical mechanism of lithium battery, and the proposed schemes pay moreattention to their practicality. the designed system achieved the intended target of theproject.