Research on a zero-voltage switching equalization topology for super-capacitor energy storage system

In order to realize the equalization of super capacitors connected in series in the storage system and improve efficiency of equalization circuits, we proposed a novel equalizing topology based on the zero-voltage switching (ZVS) for the super capacitor. Additional two small resonant capacitors which do not exist in traditional buck-boost equalization circuits and consist of a switch and an inductor are needed to achieve ZVS through resonance with the inductor. Then we discussed the switching states and equivalent circuit, introduced details of the operation principles, and analyzed the work process. At the same time, the design principle of key parameters of equalizer circuit was given. Moreover, the validity and feasibility of proposed ZVS topology are verified by the simulation and experimental results, showing that the method of equalizing is of higher efficiency compared with other methods. The system loss is small and it is easy to modify the topology for larger number of capacitors, so that it can provide fast and efficient equalization between super capacitor monomers and modules.