LUTW project: LED current sources

Exhibitor: Nino Johansson

Supervisor: Geoffrey Walker

Research Group: Embedded Systems

Industry Sector: Energy and Utilities

LUTW stands for Light Up The World which is an organisation which aims to assist poor and remote villages in developing countries obtain a reliable and affordable White Light Emitting Diode (WLED) based form of lighting.

The WLEDs being used in this project are a revolutionary, energy efficient and ultra compact new light source, combing the lifetime and reliabilty advantages of Light Emitting Diodes (LED)with the brightness of conventional lighting. These WLEDs require more power than conventional LEDs and to ensure optimum light output, they must be driven at a constant current.

Due to variations of the forward voltage drop across these WLEDs, a smart driving circuit is required to drive up to three of these WLEDs at their optimum power levels whilst also protecting them against voltage and current surges.

The driver that has been developed is a micro-controller based circuit that operates using the buck converter topology. The current in each WLED is constantly sensed by the micro-controller which then adjusts it's PWM output into the power electronics stage which then drives the WLED.

Thesis Document (PDF)