Performance Characteristics of Energy-Efficient LED Lamps Leading to Supercapacitor Assisted LED (SCALED) Technique for DC-Microgrid Applications

Most energy-efficient appliances internally operate on DC, with the potential to be powered by a DC source. Supercapacitor Assisted LED (SCALED) converter is one of the new circuit topologies under development for low voltage LED systems where a supercapacitor (SC) bank is used instead of a battery bank to buffer for fluctuations of the renewable energy source. The technique is fundamentally based on the notion of circumventing the resistive losses in a RC charging loop, coupled with the useful property of commercial 12 V LED luminaires that they operate as constant-power devices within a wide range of DC voltages applied to the lamp.When an energy-consuming LED luminaire acts as the resistive part of the RC charging loop of the SCALED approach, the voltage across the luminiare does remain constant. However, by careful measurement of the LED lamp behavior, it was identified that most 12 V commercial products work well within the topological limitations of the SCALED technique, with approximately constant brightness. The paper presents how these practical properties of low-voltage LED lamps could be effectively used in SCALED technique, which is useful in DC microgrid applications.