Modular equalization system integrating tapped-inductor-based series-resonant voltage multiplier and phase-shift switched capacitor converter for electric double-layer capacitors

A modular equalization system integrating series-resonant voltage multiplier (SRVM)-based cell equalizers and switched capacitor converter (SCC)-based module equalizers has been proposed for energy storage systems consisting of multiple cells/modules connected in series. In this system, however, cell/module equalization currents cannot be limited within desired levels, likely resulting in excessive currents as well as associated losses when cell/module voltages are severely imbalanced. This paper proposes a modular equalization system integrating tapped-inductor-based SRVM (TI-SRVM) and phase-shift SCC (PS-SCC) to limit equalization currents to desired values. The derivation procedure of the proposed equalization system is explained, followed by separate detailed analyses for the TI-SRVM and PS-SCC. The mathematical analysis revealed that both the TI-SRVM and PS-SCC offer inherent constant-current characteristics even without feedback control. An equalization test was performed using electric double-layer capacitors (EDLCs) connected in series, and the results demonstrated the efficacy of the proposed modular equalization system. © 2019 The Institute of Electrical Engineers of Japan.