Supercapacitor-based DC-DC converter technique for DC-microgrids with UPS capability

Abstract

When DC loads are powered by a DC-microgrid (DCμG) based on a renewable source such as a PV system, energy storage becomes mandatory due to fluctuating nature of the source. Localized DC-energy storage within DC-DC converters could address this requirement. A variation of supercapacitor-assisted low-dropout regulators (SCALDO) could provide localized energy storage with low-noise and fast transient response. For a generalized SCALDO configuration, end-to-end efficiency is given by (1 + k)(Vreg/Vp) where k equals n or 1/n, and n is the number of supercapacitors required to step-down an input voltage of Vp, to an output regulated voltage of Vreg. For SCALDO-based converters, (1 + k) is the efficiency improvement factor of a Vp-to-Vreg standard linear regulator.