ENERGY EFFICIENT MULTI-CHANNEL SELECTIVE DIMMING LED DRIVERS WITHOUT ELECTROLYTIC CAPACITORS

Abstract

LEDs have advantages of more efficient, durable and environmentally friendly. AC input high power LED drivers have limited lifetime compared to LEDs due to electrolytic capacitors. Hence, a method of decoupling is required to eliminate such electrolytic capacitors. This thesis proposes two methods for power ripple decoupling based on eliminating electrolytic capacitors for a two-stage multi-channel LED driver. The first method is to add an auxiliary inductive storage circuit for decoupling. The second method is based on the primary side peak current control for decoupling. For the optimized lighting applications, the LEDs connected to different channels of the multi-channel driver are required to operate at different brightness for individual channels depending on ambient light and occupancy. In such applications, a multi-channel LED driver with selective dimming of its channels presents a cost-effective and more optimized solution. This thesis also proposes three solutions for selective dimming of the multi-channel LED driver.