Potential of supercapacitors in novel power converters as semi-ideal lossless voltage droppers

Abstract

Abstract-Electrical physics text book theory tells us that charging a capacitor is much less efficient than replenishing the energy in a discharged electro-chemical battery. If a fully discharged capacitor is pumped with a charge of Q coulombs, it stores 1 2 QV 2 while dissipating the same amount of energy in the loop resistance. However, if the same charge is pumped into a re-chargeable electrochemical cell of voltage V the energy stored in the cell is QV , while the wasted energy is determined by the loop resistance and the voltage difference across the resistance. If a rechargeable battery pack is to be replaced by a supercapacitor module, this difference could seriously affect the design of power converters required, since the power converter should stop charging at a certain point to avoid overcharging the capacitor bank. However, if a useful resistive load such as heater, DC-DC converter, inverter or a lamp load is used as a part of the loop resistance in a capacitor charging loop, a significant part of this loss can be recovered. One example of this is in the supercapacitor assisted low drop-out regulator (SCALDO) technique. This paper will detail the concept of circumvention of RC loop charging loss, theoretically quantifying the same in a generalized circuit, demonstrating how this can be applied in completely novel circuit topologies such as the supercapacitor assisted LED (SCALED) converter. The paper will provide experimental results of selected SCALDO implementations and early results of SCALED technique to support this theory.

Supercapacitor‐assisted LED (SCALED) technique for renewable energy systems: a very low frequency design approach with short‐term DC‐UPS capability eliminating battery banks

“…As depicted in Fig. 19a, we see that power consumption and brightness of the LED lamps remains constant for a wide range of DC voltages (9-20 V) around the nominal value of 12 V. Two [26] efficiency improvement factor = ETEE of SCALDO regulator ETEE of related linear regulator lamps draw the highest current around 5 V. This maximum current depends on the wattage rating of the lamp as well as the driver circuit. Fig.…”

“…For this case charging process related to Figs. 15 and 16 has an efficiency is given by [26].…”

“… SCALDO converter (a) SC bank charging while minimizing series dissipation, (b) Releasing stored energy in SC bank [26]…”

Stability analysis and experimental validation of the supercapacitor‐assisted low‐dropout regulator

“…This technique is one of the most developed applications of generic SCA techniques [12]. All SCA techniques are based on the unique supercapacitor‐assisted loss management [SCALOM] theory presented in [13]. Wider research interest has been expressed in this method by various groups outside New Zealand, as indicated in [14].…”

“…In the basic technique, an array of SCs is used as a voltage dropper element in the series path of an LDO regulator. This concept is based on the loss circumvention principle of a resistor‐capacitor loop fed by a DC voltage source [13]. More discussion on the operating principle of this concept is provided in Section 1.3.…”