Research And Design On Equalization Management Unit Of Lithium-ion Battery

With the development of Lithium-ion battery technology, the large capacity ofseries connected lithium-ion battery have been more and more wildly used. However,due to limitations of technology and production processes, each single cell in thebattery pack cannot guarantee all the performance parameters are consistent. Withthe continuously charging and discharging of the battery, the difference will beincreasing, thus affecting the overall performance of the battery pack. Therefore,this paper mainly do the research and design on equalization and management unitof the lithium-ion battery.Firstly, this paper studies the bidirectional DC-AC converter topology, analysesits principle and the working process. Build a battery equilibrium model using thistopology and study its simulation, obtained the balanced results under differentparameters. To solve environmental factors changing the resonant frequencyproblems. In order to solve the problems of the change of resonant frequency causedby environmental factors, design the phase locked loop control strategy, to ensurethe balanced topology is always working in the low loss.In view of the problem of low reliability and poor versatility for equalizationsystem, adopts a master-slave overall architecture and modular design method.design the overall scheme of equalization management unit of lithium-ion batterypack, and The equalization management unit is divided into a control module,balancing module and the protection module. Design each module and computerdisplay interface based on the function and the index.Aiming at the problem of larger error in battery voltage detection ofbattery lithium, combined with the balanced topology research, designed thebattery voltage detection scheme with high accuracy. Analyses the error founded inthe detection process, design the software and hardware error compensation scheme.Finally, build an experimental platform of equalization management, analysesequalization process. Verify the reliability of the PLL at different resonantfrequencies and the feasibility of protection module by simulation. Ultimately provethe equilibrium management unit designed can achieve the required functions andmeet the design index.