An equalization management systems for lithium-ion batteries in energy storage system

An imbalance phenomenon in using lithium-ion battery pack is very common, which decreases the storage capacity and cycle life time of the batteries. So an equalization management system is required. A novel measurement cells voltage method is proposed, which can effective balance of the battery pack. A bidirectional DC/DC converter based on super-capacitor is used to equalize among the elements of the batteries. The system temporarily stores the charge drawn from the high SOC battery in the super-capacitor, and then the charge is moved into the low SOC battery without wasting energy. A appropriate control strategies of the equalization management system (EMS) was used. In order to verify the operation of the EMS, a prototype of 16 lithium-ion cells is designed, some experimental results are used to verify the validity of the proposed system.