How and where to use super-capacitors effectively, an integration of review of past and new characterization works on super-capacitors

Abstract

Abstract The Electric double-layer capacitor (EDLC) or super-capacitors are becoming increasingly popular for their high specific power and for integrating that feature with batteries, which have a high specific energy. Due to the above reason, we have attempted to understand how to use super-capacitors and characterized them, so that both battery and super-capacitors can be used together, or for low power green energy applications, like various electronics gadgets, how to use only super-capacitors. In this paper, we described the known properties of a super-capacitor relative to a conventional lithium-ion battery. The structural design of the Super-capacitors and also various engineering-based applications, related to consumer electronics, transportation etc. are also described, as a review, in this paper. As we all know, that Super-capacitor's voltage would decay over time as we draw power from it, therefore maintaining the output voltage constant for any DC-DC converter without any battery is difficult. Thus, in this paper we have shown, how we have developed a DC-DC converter circuit, without any battery, which has both feed-back and feed forward control loop, in order to maintain constant output voltage. We also have developed a mathematical equation related to super-capacitor to show the requirement for having a feed-back loop can be eliminated while using super-capacitors which have very low Equivalent Series Resistance (ESR). We have also found that for some super-capacitors one cannot pump infinite current to charge a super-capacitor because the effective parallel resistance reduces as one try to pump large current and therefore charging these capacitors to a given desire voltage may not be possible. Therefore, in order to enhance the efficiency and to reduce the charging time of super-capacitor, we proposed and developed an algorithm having gamma function-based charging methodology for super-capacitor.