Simple Modular Equalization System with Reduced Switch Count and Constant Current Characteristics for Series-Connected EDLC Modules

摘要

This paper proposes a modular equalization system integrating module- and cell-level voltage equalizers for energy storage systems consisting of series-connected multiple energy storage modules, each comprising multiple cells connected in series. Phase-shift switched capacitor converters (PS-SCCs) and tapped-inductor-based resonant voltage multiplier (TI-RVM) are employed as module- and cell-level equalizers, respectively. Since two kinds of equalizers are integrated with sharing active switches, the proposed system can halve the switch count compared to conventional modular systems, hence achieving the reduced circuit complexity and cost. In addition, equalization currents of both the PS-SCC and TI-RVM can be constant, regardless of voltage imbalance conditions, offering intrinsic current protection capability at both the module and cell levels. An experimental equalization test was performed using the prototype for three electric double-layer capacitor (EDLC) modules, each containing six cells connected in series. Module and cell voltages were equalized at different rates, demonstrating the equalization performance.