A novel voltage equalizer for supercapacitors in multiple-connection

Supercapacitors, often called EDLCs (Electric Double Layer Capacitors), 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. Firstly, the authors discuss a conventional method, using a forward converter. Under such background on various superior technologies, a novel voltage balancer is presented, employing an improved CW (Cockcroft-Walton) circuit. Characteristics of proposed circuit are analyzed and discussed.