Research On Integration Technologies Of Li-ion Batteries For Electric Vehicles

Developing electric vehicle is an effective way to solve the energy andenvironment problems. The battery is a key component of the electric vehicle, and isalso a bottleneck of the electric vehicle development. Presently，batteries used invehicles can not completely meet the requirements of electric vehicles. There are someproblems in battery life, maintenance costs, safety and so on. Integration technologies ofbatteries are of great significance for solving these problems. Based on180Ah Li-ionbattery, the thesis studies integration technologies of batteries.Using the battery tests, the characteristics of the180Ah battery arepresented.Based on the results, the3D thermal model of the battery is built.With thecomparison of common cooling styles and analyses of battery features, parallel coolingstyle is used in thermal management system. Based on computational fluid dynamics,the simulation model is built in FLUENT and the simulation study is developed.Aiming at disaccord temperature distribution of the batteries reflected by thesimulation results, a structural optimization method is proposed. The further simulationresults show that the optimization method can significantly improves the temperaturedistribution of parallel cooling system.Distributed structure is employed in battery management system. It consists of amain control unit and several data acquisition units. Internal and externalcommunication is realized by CAN network in battery management system. Maincontrol unit is the core of the system, collecting the battery pack status parameters.LTC6803-4chips are used in data acquisition units to collect cell voltage and keep cellsbalanced.To improve operation safeties of battery pack, an electrical system is presented.Finally, aiming at the problem of low efficiency of artificial calibration in batterymanagement system, automatic calibration is put forward to improve the efficiency ofcalibration.Based on the previous studies, the voltage balance, the temperature sensor locationand sealing structure are studied and thebattery system is integrated. Because the actualtemperature distribution of battery does not agree with the simulation results, a furtherstudy about the battery system is developed. The results show that the battery electrodes generate heat seriouslyand the temperature distribution of battery is greatly influenced.According to the results, the simulation model is modified and the precision is improved.Finally, the experiment results agree well with the simulation results.