Research On Equalizing Charging And Managing System For Series-connected Batteries

With society rapid development, energy and environmental issues havebecome increasingly prominent. All the countries in the world pay closeattention to these issues and try their best to ease the energy demand andpollution problems via clean energy-powered cars. Pure electric cars are moreand more get the attention of the countries all over the world, with theadvantage of less pollution and less noise, etc. Although many countries in theworld have invested large amounts of funds and manpower, the battery andbattery management has been restricting the development of electric vehicles.In case of the cell properties have been identified, the effective managementand monitoring of series-connected batteries is an important technology toimprove series-connected batteries service life and electric vehicle mileage.In the whole process of charging, the battery management system detects and manages the series-connected batteries on line, including obtaining somebasic information such as cell voltage, charge current, cell temperature,estimating of the charge(SOC), the equilibrium among the cell,series-connected batteries fault identification, communication between SCMand PC and other aspects.When we use batteries in the way of series parallel connection, theinconsistencies among the cells will be gradually intensified, and this willreduce series-connected batteries life and performance. Equalizing charge cansignificantly reduce the inconsistency of the cells and can effectively improvethe life of the series-connected batteries.After the analysis of the equalization schemes at home and abroad, basedon the study of lead-acid battery charging characteristics, basic workingprinciple, and knowing well what charging method being good at the batteryperformance and life, a suitable equalization control strategy is presented forlead-acid battery. A full set of lead-acid battery management system is built toachieve cells automatic equalization charging function. After production,debugging, testing of the whole system, a further analysis is done on equilibrium control strategy.