The Experimental Study On Equalization Controlling Of Serial Lead-acid Battery Pack Discharging

One of the key issues of Electronic Vehicles (EV) in the course of its practicality is about battery, and now various countries in the world are researching it strongly, including manufacture technique of the battery and its charge & discharging methods. At present massive works have been done on the charge and its equalization methods of the battery domestic and abroad, and some results have been yielded. But the research on battery discharging focuses mainly on discharging methods and its properties, rarely on equalization methods of the battery pack. The unbalance of serial battery pack will bring very important influences to its discharging course, and it is also a question which must have to solve in the electric automobile commercialization process. So the research on equalization discharging is the important part of discharging research, and will promote the course of EV's practicality. So there is practical meaning for studying it. On base of analyzing the research of discharging methods and the method of equalization discharging domestic and abroad, the scheme of getting the electric energy from the main line and passing through to less capacity battery in parallel equalization discharging is adopted in the thesis, and it is researched and discussed elementarily in theory and experiment. The main research items are as follows: (1) Based on lots of data getting from discharging experiment, discharging laws has been concluded and the NAA models of the best and poorest battery are established. The contents are as follows: defining the point of equalization, establishing system models and simulating, finding their point of equilibrium. (2) Combining isolation DC/DC converter used in tutor's task, the model of supplement current controlling equalization discharging system is established and simulated. Based on the results of research in the thesis, supplement current equalization discharging systems can be developed on basis of ordinary digital SCM. The system can be used to control discharge of serial battery pack, settling various problems in the process of discharging because of unbalance among the units, such as the EV can only go a short journey or some batteries over-discharge caused by the batteries which can not completing discharge at the same time, etc.