Elimination of electrolytic capacitor through high-voltage driving of LED aided by third-order harmonic current injection

Abstract

In this paper, the concept of high-voltage driving of LED is proposed to reduce the output voltage ripple of LED driver circuits by decreasing the AC current flowing through the output capacitor, leading to the potential replacement of electrolytic capacitor with other capacitor types having signif icantly longer lifetime. It also enables a direct driving of the LED load without the need for a second stage for voltage step down. To further reduce the output voltage ripple's amplitude or output capacitor's size, the well-known third-order harmonic current injection technique can be incorporated. A general design procedure including the effect of harmonic current injection is proposed and verified experimentally.

Effects of the LED modelling on the output capacitance of power converters

“…For simplicity purposes, many power converters are designed considering the linear behaviour of the load, but many loads such as batteries, DC motors and power light‐emitting diodes (LEDs) have a non‐linear behaviour; the use of equivalent resistance in such loads causes a wrong representation of the voltage and current signals. Some examples of converters with non‐linear loads in which the load is modelled as an equivalent resistance are presented in [10–20].…”