The Technology And Optimization Of Equilibrium In Power Lithium Battery Management System

Under the dual pressures of the energy shortage and the environmental pollution, the auto industry gradually recalibrate traditional energy toward the new energy based transportation, the electric vehicle industry ushered the golden opportunity of rapidly development. Because of the advantages of high energy density, high power density, low self-discharge rate, no memory effect, long life cycle and friendly to environmental. Power lithium-ion batteries have became one of the best outstanding performance in energy storage and has widely used in power supply of electric vehicle. However, due to the limitations of the ability of lithium-ion batteries manufacturing and its application conditions, the performance differences between each single cell is inevitable during the time cycle when the lithium-ion battery pack have been used. The differences would reduce the efficiency of the lithium-ion batteries and decrease its lifetime.The design of equilibrium in power lithium-ion batteries is widely studied, it is a very important part of battery management system as it can reduce the differences between each single cell in the Lithium-ion battery pack effectively, thereby improving the charge-discharge efficiency of the lithium-ion battery pack, however, the current is very small in the use of equalization circuit at this stage and the switching frequency is too fast, that can not totally satisfy the design requirement of equilibrium in the group of power lithium-ion batteries. Therefore, the design and implementation of equilibrium with a large equalization current in power lithium-ion batteries is significant.This paper mainly covers the following points about the technology of equilibrium in power lithium battery management system:1. The equilibrium circuit is designed for power lithium-ion batteries, Several balance circuit topology and its principle have been analyzed which are major used in batteries at this time, And the advantages and disadvantages of various batteries equalization circuits is Compared.2. Design the sampling circuit of the single cell voltage for power lithium-ion battery pack. The design of the single voltage sampling in this paper is based on the chip LTC6804-2 which is researched by the company named Linear Technology. The design of hardware and software for this circuit is completed.3. Design a class of equalization circuit with large current in power lithium battery management system which is constituted by a fly-back switching power supply with two isolated output and a switch array. The operation principle and design idea of the scheme is analyzed, and the specific parameter design about this hardware circuit and physical design is given through calculation.4. Based on the research of this paper, The technology of equilibrium in power lithium battery management system is summarized.