MANUTENÇÃO DAS CARACTERÍSTICAS NOMINAIS DE LUMINÁRIAS A LED: INDUTORES OU INIBIDORES DA CONFIABILIDADE (Maintenance of Led Luminaire Nominal Characteristics: Reliability Inductors and Inhibitors) Oswaldo Sanchez Junior IPT CTMNE LEO e USP IEE PPGE São Paulo - Brasil 1
IPT (2013) Infraestrutura: Sede: Cidade Universitária - São Paulo - SP Unidades: Franca e São José dos Campos - SP Unidades Técnicas: Centros e Núcleos: 11 Laboratórios e Seções Técnicas: 37 Colaboradores: 428 Pesquisadores 295 Técnicos 267 Apoio Administrativo 105 Estagiários Orçamento: R$153 M 68% P&D&I e serviços 32% GESP Produção Científica: Documentos técnicos emitidos: 26.951 Publicações: 338 Patentes: 11 2
Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 3
THE ENGINE OF LED TECHNOLOGY IN LIGHTING Source: Azevedo, I.L., M.G. Morgan and F. Morgan. 2009. The transition to solid-state lighting. Proceedings of the IEEE 97:481-510. 4
TYPES OF FAILURES ENCOUNTERED 5
A TYPICAL GAP ASSESSMENT 6
LED STRUCTURE Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 7
AREAS IN NEED OF IMPROVEMENT AND STUDY REGARDING LEDS: the internal quantum efficiency of the active region light-extraction technology current-flow design the minimization of resistive losses electrostatic discharge stability increased luminous flux per LED package purchase cost THERMAL STANDARDS DEPENDENCE: (functions of the junction temperature) light output Color life-time. Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 8
LED LIFETIMES CAN VARY FROM 3 MONTHS TO AS HIGH AS 50,000 70,000 H Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 9
ONE METHOD FOR PREDICTING THE LIFETIME OF LEDS (1) measuring the light output of samples at each test readout time; (2) estimating LED life under the accelerated test conditions (using functional curve fitting of time-dependent degradation under the test conditions) or finding observed lifetime for L50 or L70; (3) calculating an acceleration factor; and (4) predicting lifetime under the usage conditions by using the acceleration factor multiplied by the lifetime of the test condition, as shown in Eq. (1): Where: Ea is the activation energy [ev], Tu is the junction temperature at usage conditions, Ta is the junction temperature at accelerated conditions, and k is the Boltzmann constant (8.6 EE-5 ev/k) Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 10
Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 11
Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 12
ANALYSING THE BEHAVIOUR OF LED MODULE DRIVER UNDER VARIATION OF AMBIENT TEMPERATURE Fluorescence vs. Phosphorescence: Source: Moon-Hwan Chang et al., Light emitting diodes reliability review, Microelectronics Reliability 52 (2012) 762 782. 13
COLOR PERCEPTION WITH TWO DIFFERENT LEDS MODELS Source: U.S. Department of Energy 2012 Building Technologies Program Solid-State Lightning Fact Sheet 14
Overview of the test luminaire: Experimental set-up to obtain LED emission spectrum. The luminaire inside the oven is on a settled temperature and aiming its light to PTFE target we can obtain the spectrum with the radiometer. 15
Temperature at different spots of the luminaire versus the ambient temperature inside the oven: M + C: LED module and controller inside the greenhouse. M - C: LED module inside the greenhouse and outside controller. 16
Effect of the variation of the temperature over the CRI: 17
y Effect of the variation of the ambient temperature over the chromatic coordinate X and Y: 18
Effect of the variation of ambient temperature over the correlated color temperature: 19
espectro Spectrum emitted by the lamp for the MC procedure during extreme ambient temperature: 34.5 º C and 85.7 º C 20
Effect of the increased temperature on total harmonic distortion: 21
Effect of the ambient temperature on electric current: 22
CONCLUSIONS -We can note a sharply influence of the variation of the temperature in distinct components that makes up a luminaire project. -These components most of the time are sold as separated items and most of the time when these items are put together sometimes the compability between these items and the final product is not took into account. RECOMMENDATIONS -This experiment may be improved to analyze others colorimetric and electrical parameters that are part of the project of the luminaire. -Also analyze different types of luminaires, such as those used for public lightning. -The new parameters to study could be life cycle and the luminaire s degradation suiting the boundary conditions to a Brazilian reality. 23
Obrigado pela oportunidade! Contatos: Oswaldo Sanchez Junior Fone (55 +11) 3767-4588 E-mail: osanchez@ipt.br 24