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Proceedings Paper

Determining the thermal load of phosphor-converted LEDs by an iterative optical and thermal simulation procedure (Conference Presentation)
Author(s): Wolfgang Nemitz; Paul Fulmek; Johann Nicolics; Franz-Peter Wenzl
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Paper Abstract

In this contribution we discuss a combined optical and thermal simulation approach which allows us to model the thermal load of the phosphor elements of phosphor converted LED packages with high accuracy. It relies on iterative optical and thermal simulations using ASAP, which is a ray-tracing tool, for the optical simulation parts and the open-source-software gmsh/GetDP for the thermal simulations. The simulation procedure starts with the determination of the absorption intensity of the blue LED light within the phosphor layer. This absorption intensity is the input parameter for the first thermal simulation step. The thermal simulation provides the temperature distribution inside the phosphor layer which again is the input parameter for the next optical simulation step. This iterative combination of optical and thermal simulations allows to consider also the temperature dependency of the optical properties (temperature dependent luminescence loss of the phosphor, thermo-optic coefficients…) of the respective materials. The consideration of temperature induced effects is a prerequisite for an accurate simulation of the optical performance of phosphor converted LEDs, like the CCT values or temperature induced color shifts upon operation. The iteration procedure is continued until the simulated temperature distribution of the phosphor layer becomes stable which is one possible stop criterion. The simulations are verified by experimental characterisation of LED packages fabricated in accordance with the simulation model. We show that using such an iterative simulation approach allows a much more appropriate prediction of the thermal load of phosphor converted LEDs than simple thermal simulations do.

Paper Details

Date Published: 7 November 2016
PDF: 1 pages
Proc. SPIE 9953, Optical Modeling and Performance Predictions VIII, 99530C (7 November 2016); doi: 10.1117/12.2237680
Show Author Affiliations
Wolfgang Nemitz, JOANNEUM RESEARCH Forschungsgesellschaft mbH (Austria)
Paul Fulmek, Technische Univ. Wien (Austria)
Johann Nicolics, Technische Univ. Wien (Austria)
Franz-Peter Wenzl, JOANNEUM RESEARCH Forschungsgesellschaft mbH (Austria)

Published in SPIE Proceedings Vol. 9953:
Optical Modeling and Performance Predictions VIII
Mark A. Kahan; Marie B. Levine-West, Editor(s)

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