Supercapacitor Assisted Low Dropout Regulators (SCALDO) for high efficiency DC-DC converters for DC microgrid applications

Abstract

Supercapacitors are approximately one million times bigger than the conventional electrolytic capacitors, and, they come with one order lower equivalent series resistances. Given this situation, supercapacitors can be combined with low dropout regulators to achieve high efficiency linear DC-DC converters, using a patented technique- Supercapacitor Assisted Low Dropout regulators (SCALDO). In SCALDO, the load sees the high quality DC output of a linear regulator, together with very high end to end efficiency (ETEE) comparable with high frequency switch mode regulators. In SCALDO regulators efficiency improvement factors are 2, 3 and 1.33 respectively for 12-5V, 5-1.5V and 5-3.3V respectively. Series supercapacitors act as a lossless series dropper and the recovered energy is recirculated back to the linear regulator at a very low frequency in the range of fractional hertz to few tens of hertz only, eliminating any possible RFI/EMI issues. By oversizing the supercapacitors, DC UPS capability can be inserted into the SCALDO converter and these converters can be effectively used in DC microgrid applications. Paper explores the technical advantages of this unique technique, which is not a variation of charge pump technique.