Diodos emissores de luz integrados de alta corrente (EHC COB LEDs): caracterização e circuitos de acionamento

Abstract

This work is focused on the theoretical and experimental evaluation of extra-high current (EHC) chip-on-board (COB) light emitting diodes (LEDs), which feature extra-high luminous flux (up to 60 klm). The conception of high-frequency power electronic converters for this extra-high current application is also proposed. This thesis aims to propose a specific approach for EHC COB LEDs and, consequently, the investigation of two-stage drivers for the accurate operation at extra-high current and high power levels. Initially, the study presents a general introduction concerning the actual scenario and applications of solid-state lighting (SSL) based on high power levels and high luminous flux. In this context, an extensive literature technical review on the COB LED technology is carried out. An Improved Photoelectrothermal (IPET) modeling, which considers some key thermal parameters variations, i.e., the heat dissipation factor and the device junction resistance, is also evaluated concerning an EHC COB LED specific model that significantly modifies and improves the luminous flux prediction. The design methodologies are presented and applied to a 600-W EHC COB LED luminaire, which presents a typical power level required in wide outdoor environments such as sport stadiums and courts, airport highways, marine beacons, mining, and specific industrial applications. Some particular drivers are then presented for EHC COB LED applications, while the limitations of single-stage topologies as high energy reprocessing and poor efficiency for high current levels are addressed and properly referenced. In order to overcome such limitations, two-stage driving alternatives are proposed as reliable approaches for EHC COB LEDs. Besides, topologies with power control capability based on the interleaving technique are analyzed aiming at improved efficiency and controllability. Experimental results show high power factor (0.99), reduced total current harmonic distortion (in compliance with international power quality standards), high efficiency (over 90%), long lifespan due to the use of only film capacitors, and good output current control with dimming capability.