Non-isolated parallel balancing converter for serially connected batteries string

This paper introduces a new balancing topology for serially connected batteries string. The balancing operation provides fast convergence of the cells using a non-isolated parallel balancing approach with a low voltage bus that is used as an energy buffer. Balancing of the string is achieved through voltage equalization of the cells. The converter is operated in DCM and the current that flows between the cells and the bus is a function of their voltage difference. As a result, the quiescent power loss is minimal since no energy circulates in the system when the cells are balanced. Furthermore, no voltage or current sensors are required, making the implementation of the system simple and cost-effective. Theoretical analysis as well as design guidelines for the construction of the new topology are detailed and then validated on an experimental prototype that demonstrates the balancing capability of the system.