Research On Power System Of Electric Bus Based On Power Type Lithium Iron Phosphate Battery

Because the lithium battery has the advantages of light weight, long mileage and long service life, can realize the fast charging is gradually attention. Currently power lithium battery in electric vehicle application mainly exist in the battery module and the poor performance of system management problems, especially the problem of system module and power leveling, makes the battery life is far less than the battery monomer’s life. In addition, how to improve the safety of battery module is also highly concerned problem.In this paper, combined with Zibo power battery electric bus project. In this paper, the operation characteristics of the pure electric bus and the charging characteristics of the battery are summarized, and the design and Realization of the fast shallow charging and slow charging after the operation is finished. Charging process can automatically realize the conversion of different charging current stage, can real-time display the state of charge as well as the working state alarm function. The analysis of the existing charger types based on, in order to reduce the harmonic content, to realize the high power output selected 2 series 12 pulse rectifier circuit as the main circuit of the charging system in MATLAB, and Simulation of the harmonic content. The charging system to achieve high power output experiment and simulation show that, and reduce the 5 and 7 class 6N+1 harmonic.Power type lithium iron phosphate battery fast charge under thermal equilibrium management are discussed, of lithium iron phosphate battery for modeling and analysis of lithium battery cooling methods are studied, in a variety of charging and discharging experiments with MATLAB simulation were compared, and extend the cooling liquid flow channels on the basis of comparative, according to battery produced the size of heat reasonably required for the calculation of phase change materials of battery pack cooling treatment, by ANSYS software, of monomer batteries and battery fever model and compared with experimental results.Combined with the tutor host to participate in the National 863 project "high performance lithium ion power battery and electric vehicle application and assessment project, mainly composed of lithium iron phosphate 26650 cylindrical battery monomer into 130AM2V battery module is studied to design electric switch type automatic battery equalization module:four groups of 32 26650 battery units in parallel through the electric switch contact connected to form a series of battery module, the normal charging and discharging work; and the electric switch contact for access to all the battery in the battery module monomer connected in a parallel, parallel power equilibrium. According to the traditional method, the automatic parallel balance method is designed to realize the output or balance of the battery module. Selection of the battery group respectively parallel balanced positive and balanced between the anode and cathode, so that the battery group into the automatic equilibrium, and electric balance switch device movement speed faster, does not produce action spark, improve the service life of the battery group.At last, a summary of the research of this thesis is made.