MODELING OF HIGH POWER LED ILLUMINATION DISTRIBUTION USING ANN smail KIYAK 1 , Vedat TOPUZ 2 , Bülent ORAL 3 1,3 Marmara University Technical Education Faculty Department of Electrical Education, stanbul, TURKEY. 1 imkiyak@marmara.edu.tr , 3 boral@marmara.edu.tr 2 Marmara University Vocational School of Technical Sciences Computer Prog. Department, stanbul, TURKEY. 2 vtopuz@marmara.edu.tr Abstract High power light emitting diodes (HP-LEDs) are more suitable for energy saving applications and have becoming replacing traditional fluorescent and incandescent bulbs for its energy efficient. Therefore, HP-LED lighting has been regarded in the next-generation lighting. In this study, illumination distribution of white color HP-LED was examined and modeled by artificial neural network (ANN) to use at the different lighting applications. Illuminance measurements were done at different distances and voltage levels in the isolated test room. The obtained data was used to model the HP-LED illuminance distribution by ANN. As the realized ANN model, it was presented illumination distribution graphs. Matlab’s Neural Network Tool box was used for the simulations. 1. Introduction Nowadays, HP-LEDs are widely used in special lighting systems. Until only a few years ago, LEDs were used mainly as simple indicator lamps in electronics and toys. They have become as bright as and even more efficient than known light sources like incandescent bulbs or even fluorescent Lamps. These have already begun to replace incandescent bulbs in many applications, particularly those requiring durability, compactness, cool operation and/or directionality for example traffic, automotive, display, and architectural directed-area lighting [1]. Home power consumption has got important part of energy consumption in the world. In particular, the power consumption of lamps in a typical home is a factor which can’t be ignored [2]. Therefore, in recent years, there has been a growing interest in achieve energy savings for indoor illumination in buildings [3]. For energy saving, HP-LEDs are more suitable and have becoming replacing traditional fluorescent lamps because of its energy efficient, the introduction of high brightness LEDs [4]. Technological development of LED has gradually increased over the last 40 years. The main improvements have been related with light extraction, internal and external quantum efficiencies, conversion efficiency and with the compound semiconductor's structure [5]. Consequently, HP-LED lighting offers many potential benefits over incandescent, halogen, fluorescent and gas/arc lamps, solid-state light sources and have been regarded as the most potential light source in the next- generation lighting [6,7]. Several advantages have made HP-LEDs, which are a revolution in lighting, very attractive to general illumination with white light [8]: • Incredibly long life, lasting between 50,000 to 100,000 hours, • High efficiency • Work on dimmable switches and • Quick turn on and turn off, • Environmentally friendly, • Good color saturation, • Able to withstand shock, vibration and environmental extremes, • Low maintenance requirements, • Safe DC voltage operation, • Superior color range and brightness. The illumination efficiency of HP-LEDs can be defined as the ratio of the output optical power to the input electrical power. As the direct current (dc) drive current increases, the optical output power saturates, or the illumination efficiency degrades significantly. Illumination efficiency of HP-LEDs is one of the most critical parameters for the above applications, which require high brightness and high output power [9]. Light control for indoor illumination is necessary in order to save energy. Lights are usually controlled by on/off switches. Surely, the user can switch a light on or off remotely by connecting a specific device to a PC. However, there has to be at least a PC, consuming a rather large amount of power 24 hours a day, for the control mechanism. Moreover, this inconvenient practice comes at a high cost for the user. In some designs one must install specific hardware and software to control the lights, resulting in unacceptable costs. Furthermore this type of system cannot detect either the temperature of the human body or the room light intensity [2,10-12]. 2. High Power LED and Solid State Lighting LEDs are semiconductor devices that emit photon energy (light) when an electrical current is passed through them. A diode basically consist of n- and p- type semiconductors doped with intentional impurities to create electron rich and hole rich materials, respectively. The junction of n- and p- type semiconductors makes a p-n junction. Positive (holes) and negative (electrons) charges are injected into the p-n junction. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon. This process is known as electroluminescence. The color of the emitted light depends on the band gap of the semiconductor. It can be tailored from deep ultraviolet to infrared by selecting the proper semiconductor materials. “Fig. 1” is a schematic representation of the relationship of the light emitting diode [13, 14]. II-137