Proposal and improvements of voltage equalizers for EDLCs

Supercapacitors offer high energy density and long life span, so various applications may be anticipated in the realm of energy storage devices, such as those used in electric vehicles or electric power stabilization in power systems, etc. However, since the voltage limit is low of the devices, it is necessary to connect them in series or parallel. In addition, it is required that they be used in the region of their critical voltage limit or capacity limit. In order to apply them efficiently, the devices should be used with balanced voltage. In this paper, a novel voltage balancer is presented, employing a CW (Cockcroft-Walton) circuit. Characteristics of proposed circuit are analyzed and improved especially about charging response.