LCC S2C and Buck–Boost C2C Topology Complementary Method for Hierarchical Battery Energy System

The series connection of batteries is widely used in various scenarios. However, due to the influence of battery imbalance, the performance of the battery pack will be degraded, scrapped in advance, and even cause safety problems. At present, cell-to-cell (C2C) and series-to-cell (S2C) topologies methods have been proposed for hierarchical battery energy system. To combine the advantages of various methods for lower control complexity, high circuit scalability, and high equalization efficiency, a hybrid hierarchical equalizer based on LCC resonant converter and buck–boost unit equalizer is proposed in this paper. This topology applies LCC resonant converter to serial-to-module (S2M) equalization, selects energy transmission path through multiplexing network, and adopts buck–boost equalizer in each module. The simulation results show that the equalizer can reduce the voltage difference of unbalanced batteries by 99.5% within 1 s and that indicates the feasibility of the equalizer. Compared with the existing equalizer, the equalizer proposed in this paper has higher efficiency and lower control complexity. This paper can provide theoretical guidance for the design of new battery equalizer and its application in high efficiency battery equalizer.