A low-cost time shared cell balancing technique for future lithium-ion battery storage system featuring regenerative energy distribution

A new cell voltage equalizer topology for future plug-in hybrid electric vehicles (PHEV) or renewable energy storage has been proposed in this paper. This topology has fewer components compared to the conventional topologies found in the literatures, and therefore, it could reduce cost and fabrication complexity. This new circuit is based on a time shared fly-back converter, and any number of series connected cells could be used in a string without any apparent issues. Each cell in a string shares this converter during its allocated time slot provided by the microcontroller. In addition, dynamic allocations of the time slots are possible to achieve faster cell balancing, and the circuit dynamically distributes depleted charge among cells in a regenerative fashion - ensuring a very high efficiency. The prototype of a four-cell lithium-ion battery balancer circuit was designed and implemented. Simulation and experimental results are presented to verify the operation of the new topology.