Research On Equalization Charge Technology Of The Lithium Battery Series In Battery Electric Vehicle

With problems of energy shortage and environmental pollution being increasingly serious, pure electric vehicles which have a clean and environmentally friendly feature are become mainstreams in the energy industry. However, the inconsistencies in the charging process of the lithium-ion battery pack series, which is as the direct-drive energy of the pure electric car, to make pure electric vehicles popularity being restricted, so the in-depth study on the equilibrium ion battery charging technology is necessary.In this background, this paper studied the equilibrium charging methods, control methods, equilibrium charging monitoring and control system of the lithium-ion battery pack, in order to promote the popularity of pure electric vehicles.First, the paper researched and analyzed the charging characteristics and the technologic advances of lithium batteries, and summarized the reasons for the inconsistency of lithium batteries.Secondly, a lossless energy transfer equalizer circuit which was relatively simple and flexible was improved, aimed at the problems such as the unbalanced available capacity and the shorten service life caused by the different monomer battery performance during the latter part of lithium-ion battery pack charging. Then, According to the lithium battery equalization process is a discrete time decision-making process, the paper adopt a recharge balance control scheme for power lithium batteries based on Markov Decision algorithm. What’s more, using each cell voltage as the control variables, this paper forecasted and planned direction of energy transfer between the cells, selected the optimal transition path, so that a balanced outcome to meet the objectives and requirements.Through the simulation and analysis of experimental results, the paper proved that the feasibility of the equalization circuit and balance control program, and also proved that the balancing efficiency and balancing effectiveness of the balance control strategy for lithium-ion battery pack based on Markova decision algorithm are both better than those of the balance control strategy based on fuzzy control algorithm, so achieved a charge balance during the lithium-ion battery pack charging late stage.And through the comparison between the balance control strategy for lithium-ion battery pack based on Markova decision algorithm and that based on fuzzy control, this paper proved that the equilibrium effect of the balance control strategy based on Markova decision algorithm is improved obviously, can better realized the late charge balance of lithium batteries.Finally, aim at the issues of vehicle power battery such as long charging time and the charging process fails as well as the having no timely access to the results after charging, the paper designed a vehicle power battery monitoring system based on the internet of things. The paper analyzed and described the overall system and then completed the building and the testing of the hardware design and software platform of the internet of things system. Test results shows that the human-computer interface using the LabVIEW virtual instrument platform is able to perform the real-time remote monitoring, and the data transmission between monitoring subsystem and control subsystem can be completed effectively. It verifies the real-time, accuracy of the system, and provides convince to users.