A universal two-level changeover circuit of super-capacitor bank for energy storage systems

Since the traditional two-level changeover circuits are not capable of obtaining both high energy utilization efficiency and low bank voltage fluctuation, a novel three-level changeover circuit of super-capacitor bank was proposed for energy storage systems in this paper. The proposed circuit has symmetrical structure. Thus, currents flowing in each branch are always identical. The amount of switches of the proposed circuit is limited to its theoretical minimum. At last, charging-discharging simulations were performed to demonstrate the performances of the proposed circuit during both charging-discharging processes. Its energy utilization efficiency and voltage fluctuation are 88.9% and 33.3% respectively, better than that of traditional two-level changeover circuits.