Research On Equalization Voltage Of Lithium Battery Pack For Apllication On Electric Vehicles

Following with the sustainable growth of the automobile, energy saving and environmental protection are get more and more attention by people. Electric energy that can originally come from solar energy, wind energy, hydropower and other clean renewable energy is the most common form of energy. Therefore the development and spread of electric car is the best way to solve the energy crisis and environmental pollution. Lithium-ion batteries is widely used for its superior characteristics, But the technology level limit of battery and vehicle power performance demand, the vehicle power battery must be composed by many single cells in series. Inconsistency maybe appear for huge Numbers of single batteries, inconsistency problem will reduce the battery pack use performance and service life, so the battery equalization systems are introduced to control the spread of inconsistency of the battery pack. Equalization system of battery pack has important practical significance. Scholars at home and abroad have series research of lithium ion battery equalization problems, but there is complex structure exists in the balancing circuit and the control algorithm is difficult to achieve. Needle above problems design a new type of balance circuit and the fuzzy controller for lithium-ion battery pack balanced control, main works are as follows.Lithium-ion’s working principle and feature was studied in detail, analyzes inconsistency source, harm and solution measures of the battery pack. Points out the advantages and disadvantages of the equalization circuit on the basis of the analysis of several commonly used balance circuit.Design the hybrid type of equilibrium circuit according to the characteristics of the lithium-ion battery, the equalization circuit which structure simple, easy to implement, the high efficiency, eliminate the problem of voltage oscillation. On the basis of the equalization circuit the hardware system were established.Design the balanced strategy and fuzzy controller for improve the efficiency of balance and control accuracy according to the design equilibrium circuit.In the simulation environment the lossy type of equilibrium system, nondes-tructive equilibrium system and their hybrid system are setted up respectively, through comparative and analysis, the hybrid equilibrium system combines the advantages of both, its not only has simple structure, the high efficiency and ruled out the equili-brium of terminal voltage oscillation problem.