Quantified Insights into LED Variability

Bornoff, Robin; Mérelle, T.; Sari, Josephine; Bucchianico, A.A. Di; Farkas, G.

doi:10.1109/therminic.2018.8593315

Cited by 17 publications

(9 citation statements)

References 5 publications

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“…This may have occurred due to the larger scatter in the phosphor quality and also indicates that the binning was performed at a single ( _ , _ ) operating point ( Figure 20). This finding corresponds to the results of the variability analysis of the thermal properties of the blue and white LED samples [46,47], where a significantly larger scatter of the properties of the white samples was found.…”

Section: The Predictive Power Of the Physics Based Modelsupporting

confidence: 89%

“…In all equations, the thermal voltage and the bandgap voltage were calculated for the actual junction temperature (given in Kelvins). In the bandgap voltage formula, the peak wavelength was approximated by a relationship derived from Equations (7) and (8) for values of close to 300 K: This finding corresponds to the results of the variability analysis of the thermal properties of the blue and white LED samples [46,47], where a significantly larger scatter of the properties of the white samples was found.…”

Section: The Actual Implementation Of the Physics Based Modelsupporting

confidence: 60%

“…Within this work, the properties of the junction-to-ambient heat-flow path of LED populations were investigated. The analysis was done on 11 royal blue and 10 phosphor converted white LEDs [46,47,49].…”

Section: Modeling An "Led Type" and Parameter Extractionmentioning

confidence: 99%

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Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

et al. 2019

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This paper presents our approaches to chip level multi-domain LED (light emitting diode) modelling, targeting luminaire design in the Industry 4.0 era, to support virtual prototyping of LED luminaires through luminaire level multi-domain simulations. The primary goal of such virtual prototypes is to predict the light output characteristics of LED luminaires under different operating conditions. The key component in such digital twins of a luminaire is an appropriate multi-domain model for packaged LED devices that captures the electrical, thermal, and light output characteristics and their mutual dependence simultaneously and consistently. We developed two such models with this goal in mind that are presented in detail in this paper. The first model is a semi analytical, quasi black-box model that can be implemented on the basis of the built-in diode models of spice-like circuit simulators and a few added controlled sources. Our second presented model is derived from the physics of the operation of today’s power LEDs realized with multiple quantum well heterojunction structures. Both models have been implemented in the form of visual basic macros as well as circuit models suitable for usual spice circuit simulators. The primary test bench for the two circuit models was an LTspice simulation environment. Then, to support the design of different demonstrator luminaires of the Delphi4LED project, a spreadsheet application was developed, which ensured seamless integration of the two models with additional models representing the LED chips’ thermal environment in a luminaire. The usability of our proposed models is demonstrated by real design case studies during which simulated light output characteristics (such as hot lumens) were confirmed by luminaire level physical tests.

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Section: The Predictive Power Of the Physics Based Modelsupporting

confidence: 89%

Section: The Actual Implementation Of the Physics Based Modelsupporting

confidence: 60%

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Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

et al. 2019

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“…Yet, the peak might become blurred and impossible to identify by this method for some LEDs configurations. In this case the R th_J2T_SF value is determined by a method inspired by [40] as cumulative R th value correspondent to characteristic C th_J2T value which is defined as:…”

Section: _ _mentioning

confidence: 99%

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

et al. 2019

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Thermal transient testing is widely used for LED characterization, derivation of compact models, and calibration of 3D finite element models. The traditional analysis of transient thermal measurements yields a thermal model for a single heat source. However, it appears that secondary heat sources are typically present in LED packages and significantly limit the model’s precision. In this paper, we reveal inaccuracies of thermal transient measurements interpretation associated with the secondary heat sources related to the light trapped in an optical encapsulant and phosphor light conversion losses. We show that both have a significant impact on the transient response for mid-power LED packages. We present a novel methodology of a derivation and calibration of thermal models for LEDs with multiple heat sources. It can be applied not only to monochromatic LEDs but particularly also to LEDs with phosphor light conversion. The methodology enables a separate characterization of the primary pn junction thermal power source and the secondary heat sources in an LED package.

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“…Their variability might have a significant impact on the product performance. Variability among the different LED samples was also investigated [27][28][29][30][31]. In our actual study 11 royal blue LED samples and 11 samples of their phosphor converted white counterparts (LED having the blue peak at the same wavelength as the peak wavelength of the royal blue) have been measured and modelled.…”

Section: Variability Assessment Of the Led Digital Twinmentioning

confidence: 99%

Luminaire Digital Design Flow with Multi-Domain Digital Twins of LEDs

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Bornoff

et al. 2019

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At present, when designing a Light Emitting Diode (LED) luminaire, different strategies of development are followed depending on the size of the company. Since on LED datasheets there is only limited information provided, companies designing LED luminaires spend a lot of effort gathering the required input of LED details to be able to design reliable products. Small and medium size enterprises (SMEs) do not have the bandwidth to gather such input and solely rely on empirical approaches leading to approximated luminaire designs, while larger companies use advanced hardware and software tools to characterize parts, design versions, and finally optimize all design steps. In both cases, considerable time and money is spent on prototyping, sampling, and laboratory testing. Digitalization of the complete product development (also known as Industry 4.0 approach) at all integration levels of the solid state lighting (SSL) supply chain would provide the remedy for these pains. The Delphi4LED European project aimed at developing multi-domain compact models of LED (for a consistent, combined description of electronic, thermal, and optical properties of LEDs) as digital twins of the physical products to support virtual prototyping during the design of luminaires. This paper provides an overview of the Delphi4LED approach aimed at supporting new, completely digital workflows both for SMEs and larger companies (Majors) along with some comparison with the traditional luminaire design. Two demonstration experiments are described: One to show the achievable benefits of the approach and another one to demonstrate the ease of use and ability to be accommodated in a larger scale product design for assessing design choices like e.g., number and type of LEDs versus electrical/thermal conditions and constraints, in a tool agnostic manner.

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Quantified Insights into LED Variability

Cited by 17 publications

References 5 publications

Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

Luminaire Digital Design Flow with Multi-Domain Digital Twins of LEDs

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