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

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 significantly 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.