A step-up switched-capacitor converter for LEDs applied to photovoltaic systems

Abstract

This paper proposes a DC-DC step-up converter with a switched capacitor to power light-emitting diodes (LEDs), which may be applied to an autonomous system, e.g. PV system. In the converter is used a small additional inductor operating in discontinuous conduction mode (DCM) which allows zero current switching (ZCS), reducing circuit losses. Moreover, the LED current can be stabilized through the switching frequency as a function of input voltage only. Thus, the converter does not need current sensors, allowing cost reduction. The prototype assembled in laboratory was designed for a lamp of 54 W, operating in a frequency of approximately 153 kHz and presented an efficiency of 93%.