Charge equalizer using a Cockcroft-Walton vottage multiplier for series-connected supercapacitors

Conventional cell equalizers derived from dc-dc converters consist of numerous switches, sensors, or transformers; thus, their cost and circuit complexity are high. In this paper, Cockcroft-Walton charge equalizers consisting only of capacitors, diodes, and an ac power source are presented. In addition, a novel charge equalizer that outperforms the Cockcroft-Walton charge equalizers is proposed. The operating principle and derivation of an equivalent circuit are explained. Experimental charge tests were performed on series-connected supercapacitors to demonstrate its charge performance.