Cell-level hybrid architectures for active balancing of serially-connected batteries

This paper introduces two new hybrid architectures for active balancing of serially connected batteries string. These architectures feature simple sensorless implementation, modularity, design flexibility and reduced component count. The key point of the balancing concept is that by merging two active balancing approaches, additional power paths between batteries cells are created, but without the penalty of extra conversion stages. Furthermore, the balancing systems operate in DCM and energy is transferred according to voltage difference between the cells. Therefore, no energy circulates in the system when the cells are balanced, resulting in expedited convergence and low power losses. Experimental results have been obtained by a prototype of six serially connected batteries; demonstrate the superiority of the new balancing system by comparison to conventional approaches.