Research On Balance Of Power Lithium Battery Pack

In order to meet the performance of PEV demand, the car's energy was provided by series of power batteries. With the wide application of PEV, the consistency problem of on-board dynamic battery has become more and more attention by people. As the existence of consistency problem, available capacity and service life of battery pack are much less than that single fuel cell. Therefore, the balance management of the battery pack has important practical significance of using a group of cells. This paper mainly research on the equalization technique of power Li-ion battery pack.Firstly, this paper introduces the causes of battery consistency problem and its effects, and points out the significance of equilibrium management. As the lack of traditional evaluation system of consistency which based on the battery voltage difference, this paper expounds on consistency problem of battery from DC internal resistance, polarization voltage, SOC and capacity. Then, for the consistency problem has effected on the available capacity of the pack, energy efficiency is proposed to evaluate the consistency of the battery pack. According to the target of increasing battery capacity utilization, equilibrium strategy is proposed based on the capacity and SOC. And the method to judge of the two equilibrium strategy has been studied. The strategy based on capacity cannot meet the requirements of a balance on line has been pointed out.Finally, this paper compares the existing programs of equalizer circuit, and chooses the charging and discharging balance method. According to the on-board and online equilibrium requirements, hardware circuit has been designed and algorithm has been embed into the circuit which based on the SOC strategy. An experiment platform has been put up to test the strategy and the circuit. And the effectiveness of strategies and the circuit has been verified.