A modularized charge equalizer using battery monitoring IC for series connected Li-Ion battery strings in an electric vehicle

In the proposed equalizer, series-connected battery string is modularized into M modules. Each module has voltage monitoring IC and cell selection switch for K cells. The monitoring IC not only monitors the battery voltage, but also controls the selection switch for cell balancing. With this configuration, the battery monitoring and balancing can be effectively merged by the same controller. Moreover, by using a central equalization converter, great size reduction and outstanding balancing performance can be obtained for a large number of battery cells. In this paper, to demonstrate usefulness of the proposed work, a prototype for 88 lithium-ion battery cells is optimally designed and implemented. Experimental results verify that the proposed equalization method has good cell balancing performance.