A5028474170- GaN-based semiconductor devices and materials
- Semiconductor Lasers and Optical Devices
- Impact of Light on Environment and Health
- Thin-Film Transistor Technologies
- Engineering Applied Research
- Green IT and Sustainability
- Advanced Sensor Technologies Research
- Silicon Carbide Semiconductor Technologies
- Sensor Technology and Measurement Systems
- Vibration and Dynamic Analysis
- Luminescence Properties of Advanced Materials
- Color Science and Applications
- Semiconductor materials and devices
- Advanced optical system design
- Electrostatic Discharge in Electronics
- Building Energy and Comfort Optimization
- 3D IC and TSV technologies
- Thermography and Photoacoustic Techniques
- Computer Graphics and Visualization Techniques
- Surface Roughness and Optical Measurements
- Scientific Research and Discoveries
- Real-time simulation and control systems
- Radiation Detection and Scintillator Technologies
- Organic Light-Emitting Diodes Research
- Radiative Heat Transfer Studies
Budapest University of Technology and Economics
2015-2024
This paper presents our approaches to chip level multi-domain LED (light emitting diode) modelling, targeting luminaire design in the Industry 4.0 era, support virtual prototyping of luminaires through simulations. The primary goal such prototypes is predict light output characteristics under different operating conditions. key component digital twins a an appropriate model for packaged devices that captures electrical, thermal, and their mutual dependence simultaneously consistently. We...
The advantages of light emitting diodes (LEDs) over previous sources and their continuous spread in lighting applications is now indisputable. Still, proper modelling lifespan offers additional design possibilities, enhanced reliability, energy-saving opportunities. Accurate rapid multi-physics system level simulations could be performed Spice compatible environments, revealing the optical, electrical even thermal operating parameters, provided, that compact model prevailing luminaire...
The multi-domain operation of LEDs characterized by the tight coupling between their electrical, thermal and optical properties manifests not only on chip package level, but has to be tracked LED products higher integration level such as modules or luminaires. At present system numerical analysis integrated is typically performed different design teams dealing with separately. One reason this practice lack a unified modeling approach in which right models are used for chip, package, module...
LEDs (Light-Emitting Diodes) are widely applied not only in decorative illumination but also everyday lighting buildings, flats, public areas, and automotive fields. These application areas often mean harsh environments, for example, regarding the humidity content of surrounding air: besides outdoor illumination, even household use cases (kitchen, bathroom, cellar) may represent extreme temperature variations (often reaching relative levels close to 100%) these devices; thus, their...
Characterization of LEDs and other semiconductor devices demands at least accurate monitoring the junction temperature (Tj), also its control in more complex cases. In practical LED lighting appliances "hot lumens" are meaningful, as most lamps used steady state with power applied. Analysis cold provides only indirect information about intended operation. On hand, direct T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> measurement is...
Large area multi-chip LED devices, such as chip-on-board (CoB) LEDs, require the combined use of chip-level multi-domain compact models (Spice-like models) and proper description distributed nature thermal environment (the CoB substrate phosphor) chips. In this paper, we describe a new numerical solver that was specifically developed for purpose. For chip-level, modeling approach Delphi4LED project is used. This model coupled to finite difference scheme based used simulate phenomena in...
Operation of LEDs is highly affected by their junction temperature. However, for proper thermal characterisation a well fitted K-factor function needed within its validity range. Correction the parallel resistance during transient testing also needs special care. This paper focuses on issues applying correct value or higher polynomial fit to temperature dependent forward voltage characteristics tested LEDs. Our work based JEDEC's LED standards, and outcome set practical recommendations...
Our goal is to provide an overview of a few theoretical and practical issues current LED testing standards recommendations that we encountered during round-robin five different types power LEDs our work in the frames Delphi4LED project. We focus on JEDEC JESD51-14 JESD51-51 have been commonly applied for thermal since these were published. CIE has also published their new technical report optical high with special attention paid setting LEDs' junction temperature measurements. An enhanced...
The ability to dim LEDs is a big advantage compared previous light sources, but it can also lead new aging mechanisms. Due the different coefficients of thermal expansion individual structural layers, temperature cycle negatively affect main path. In this article, we investigate how dimming frequencies influence and what extent they impair conductivity layers belonging time constants. methodology joint examination integral structure function constant spectrum described, i.e., determination...
In this paper, a novel method is presented to estimate the parameters of SPICE-like multi-domain model light-emitting diode (LED) chips developed and proposed by Delphi4LED project. The estimation algorithm employs modified Nelder-Mead method, as gradient methods original version fail properly handle problem. By using new, in paper are estimated faster, compared previously used brute-force algorithm-based parameter extraction process, allowing same precision LED model. modification procedure...
Traditionally incandescent and fluorescent light sources were mostly used in a single operation point their relevant characteristics was described by few parameters datasheet. The emitted of LED products depends on current temperature heavily the behavior LEDs actual use can be predicted only complex models physical roots. paper summarizes targets methodology European Delphi4LED project aiming elaboration measurements for identifying electrical-optical-thermal models. Measurement examples...
Temperature dependence of solid state lighting products is often not considered. Lighting are designed either to be too robust fulfil the requirements under any possible environmental conditions, or fail perform minimal expectations due high ambient temperature. However, temperature dependent nature LEDs even could a new benefit, taking it into account in design stage. Keeping light output values at desired level would cost efficient solution. This paper shows power saving effects smart...
This paper presents a method of thermal characterization heat-sinks aimed at cooling socketable LED modules. The suggested measurement procedure resembles the transient dual interface JEDEC JESD51-14 standard: two measurements are performed with different qualities heat-sink surface mating structure functions section identified such represents solely measured heat-sink. Step wise approximation obtained function is used to create DCTMs heat-sinks, fast system level simulations
Light output performance of power LEDs is sensitive to the junction temperature and also changes with elapsed lifetime device. A smart control achieve constant light LED based products would be advantageous in many applications such as street-lighting, resulting e.g. considerable savings when forward current reduced ambient temperatures are lower. Also, continuous compensation lumen depreciation during product improve visual comfort. Both could made while aging phenomena device slowing down....
In a recent H2020 European wide research project (Delphi4LED, www.delphi4LED.eu)extensive study for generating multi-domain compact LED models based on measurement data was concluded.In this context combination of the latest testing standards and recommendations JEDEC CIE have been applied in new modelling methods developed order to capture multi -domain operation LEDs purpose simulation.A valid question is: how representative model is type an package, select nominal device inherent...
This paper presents an effective and appropriate method to calculate the "hot lumens" of a street-lighting luminaire. The proposed multi-domain LED model is described here with testing simulation results. practical need for such simulations demonstrated through application example.
The possibility of easy, PWM-based dimming LEDs is a big advantage compared to former light sources, but at the same time, it may also result in additional aging mechanisms continuous DC operation. Due different coefficients thermal expansion each structural layer, temperature cycling can degrade main heat conduction path LED chips. In this paper, we examine, how frequencies affect LEDs, and what extent they impair conductivity layers belonging time constants.
In a recent European H2020 project on LED characterisation and modelling (Delphi4LED, www.delphi4LED.eu)the major target was to represent physical package types by their digital twins in form of multi-domain compact models.In this specific task devoted CoB LEDs.Phosphor converted white LEDs are large area devices ceramic substrate high thermal conductivity, with few dozens chips mounted, covered phosphor layer.Such real technical challenges both terms measurement modelling.In paper we report...
Simulation of the emitted total luminous flux an LED-assembled luminaire at operating temperature is a multi-domain task since its operation can be described with interaction electrical, thermal and optical domains.Multi-domain modelling LEDs was main target recent European H2020 project (Delphi4LED) in order to make so called digital twins widely available for industrial development purposes.One problem these measurement based models that they refer fresh devices 0h real operation.It would...
The multi-domain operation of blue pump LEDs in a chip-on-board (CoB) device cannot be described properly by the existing chip level compact models and package thermal model because their is strongly affected such parts environment as substrate or phosphor. In this case mix modelling distributed approaches need to used. This paper presents method that applies LED way for simulation chips Finite Volume Method based description whole package, including temperature dependent light conversion...