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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 l...
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Context 1
... to date power LED devices approximately have the band diagram shown in Figure 8 (based on [38] and [43]). The active portion of the LED die consists of "bulky" p and n confinement layers, an electron blocking layer (EBL), and a sandwich of quantum barrier layers (QB) and quantum wells (QW). ...
Citations
... The above architecture can then be integrated with switching circuitry and higher order mixed signal system blocks for programmed control of large arrays of QW µLEDs. Furthermore, the workflow and behavioral models can be assimilated into chip-level analysis of LEDs to determine luminous properties [20], [21], [22]. The double exponential derived in this letter is a function of the intrinsic semiconducting properties of the semiconducting stack under consideration. ...
Monolithically integrated GaN devices have gained traction due to their lowered cost and suitability to produce large-scale optoelectronic and digital communication systems. To address the unavailability of realistic compact modeling of these devices and their circuitry, a framework for temperature-dependent finite element multiphysics simulation of high-density micro-light-emitting diodes (
$\mu$
LEDs) integrated with commercial high electron mobility transistors (HEMTs) has been developed. To incorporate the behavioral model extraction into Cadence, the multiphysics-based behavioral model is extracted in Verilog-A. Each proposed quantum well
$\mu$
LED is individually modeled under varying temperature conditions, allowing for comprehensive analysis at both the behavioral and circuit-level regimes. This analysis is performed in Cadence Virtuoso design environment, comprising a driving HEMT, and a CMOS ASIC is subsequently proposed. The peak internal quantum efficiency (IQE) of each
$\mu$
LED exhibits a variation of 0.046%/
$^{\text{o}}$
C with wide operational current densities of 0.01–450 A cm
$^{-\text{2}}$
. This leads to the development of a definitive tool kit for the practical modeling of GaN-based devices, which can be further integrated with CMOS devices to facilitate optoelectronic circuit design.
... Many types of power LEDs offered by Cree is selected and compared to validate the accuracy of the model under different cooling conditions. Furthermore, multi-domain models for packaged LED devices are developed by researchers in [3]. Their electrical, thermal, and light output characteristics are captured and understand their mutual dependence. ...
This paper presents a comprehensive analysis of parameters required for accurate modeling of Light-Emitting Diodes (LEDs) and their subsequent use in simulator software for comparing practical and simulation results. The focus of the study is on parameter extraction from the LED model, including key variables such as LED capacitance value, saturation current, emission coefficient, shunt resistance, and series resistance. The research showcases a practical methodology for parameter extraction that yields results closely aligned with simulation outcomes when the extracted parameters are incorporated into the simulation framework. This study is better than previous studies from the point of extracting the five parameters for LED modeling through the use of several experiments which their practical results has been verified by implement simulation approaches.
... Therefore, the aim of this article is to propose a measurement methodology fully compatible with requirements for the pulsed (iso-thermal) and transient characterization of LEDs. This kind of analysis requires the design of a specific measurement setup equipped with an accurate current sources, capable of high current output (up to 1 A, for power LEDs), high temporal stability in order to record the temperature variations with high accuracy, and fast settling times (shorter than LED self-heating transients [15]). Thanks to the use of a feedback network based on an instrumentation amplifier and a subtractor, the circuit is intrinsically immune to supply voltage fluctuations and ensures temporal stability better than 0.1% over a long (more than 100 s) pulse generation interval. ...
A precise measurement of optical power, forward voltage, and junction temperature of light-emitting diodes (LEDs) is the key for characterization and health monitoring of these devices. In many cases, LED characterization is carried out with relatively long (10 ms and longer) pulses, that is, in conditions in which self-heating can significantly impact measurement results. To overcome this limitation, this article proposes a fast and versatile measurement approach based on a specifically designed current source, with a maximum current of about 1 A, high stability (variations under 0.1%) and settling time
$\bm{<}$
20
$\bm{\mu}$
s, and demonstrates its applicability to pulsed and transient characterization of power LEDs. The proposed system has the inherent advantages of 1) permitting a fast pulsed characterization of the devices, which—as we demonstrate—is much more accurate than quasipulsed or dc analysis; 2) allowing isothermal characterization of LEDs without requiring long settling times, with beneficial impact on the throughput of LED characterization; 3) allowing characterization of the voltage heating transient (during constant current operation), which is the key for junction temperature and thermal resistance extraction, as well as for the development of compact models; 4) monitoring the optical power during the self-heating transient; and 5) the spectrum of the device providing additional information, such as the peak-shift or the phosphor behavior. The efficacy of the proposed approach has been demonstrated by testing commercial LEDs: the results clearly indicate that a fast (
$\bm{<}$
20
$\bm{\mu}$
s) LED characterization is necessary for a proper extraction of the main spectral parameters and of the related temperature dependence.
... where h c is the convection coefficient of flat surfaces, Nu is the Nusselt number (-), and L is the characteristic length in meters (for a vertical wall, it is the height). The Nusselt number for forced convection is described by Equation (8) The Prandtl number can be obtained using Equation (11) [45]: ...
The supply of energy with the correct parameters to electrical appliances is possible with the use of energy converters. When a direct current is required, rectifier bridges are needed. These can be made using rectifier diodes. The problem of excessive junction temperatures in power diodes, which are used to build rectifier bridges and power converters, was recognized. For this reason, research work was carried out to create a model of a rectifier diode placed on a heat sink and to analyze the heat dissipation from the junction of this diode under forced convection conditions. The results obtained from the simulation work were compared with the results of thermographic temperature measurements. The boundary conditions chosen for the simulation work are presented. A method is also presented that determined the convection coefficient under forced convection conditions. The difference between the simulation results and the results of the thermographic measurements was found to be 0.1 °C, depending on the power dissipated at the junction and the air velocity around the diode.
... This relationship is described by Equation (2) [27]: where I pn is the current, q is the electron charge (1.6·10 −19 C), k is Boltzmann's constant (1.381·10 −23 J/K), V pn is the voltage across the junction, T j is the junction temperature, γ is a constant approximately equal to 3, and E g is the band gap of Si (1.12 eV) at T = 275 K. The relationship between forward voltage V F and forward current I F is shown in Figure 2 [28]. The dependence V F = f(T j , I F = const) can be determined in the circuit shown in Figure 3. ...
... where Ipn is the current, q is the electron charge (1.6·10 −19 C), k is Boltzmann's constant (1.381·10 −23 J/K), Vpn is the voltage across the junction, Tj is the junction temperature, γ is a constant approximately equal to 3, and Eg is the band gap of Si (1.12 eV) at T = 275 K. The relationship between forward voltage VF and forward current IF is shown in Figure 2 [28]. The dependence VF = f(Tj, IF = const) can be determined in the circuit shown in Figure 3. ...
... Pr (-) is the Prandtl number, and Gr (-) is the Grashof number. The Prandtl number can be obtained using Equation (15) [28]: ...
Monitoring the temperature of a semiconductor component allows for the prediction of potential failures, optimization of the selected cooling system, and extension of the useful life of the semiconductor component. There are many methods of measuring the crystal temperature of the semiconductor element referred to as a die. The resolution and accuracy of the measurements depend on the chosen method. This paper describes known methods for measuring and imaging the temperature distribution on the die surface of a semiconductor device. Relationships are also described that allow one to determine the die temperature on the basis of the case temperature. Current trends and directions of development for die temperature measurement methods are indicated.
... The free holes and electrons are confined to QW during the operation. The wavelength of the emitted light is subject to the E g in WQs, whereby a broader E g of the quantum barrier truncates the absorption of emitted photons but improves the efficiency of charge injection into the WQs [31]. The color of the light emission can be tuned by modifying the composition and width of the QWs. ...
Light-emitting diodes (LEDs) are considered the most promising technology for future display and lighting applications due to their high efficiency, durability, long lifespan, and eco-friendliness. Inorganic and organic LEDs (LEDs and OLEDs) are the key components in current display and lighting applications. Porous materials are a fast-developing field of study that has unraveled and expanded an extensive array of novel properties and applications. The structural and morphological parameters of the hosted semiconductor can be controlled by modifying the pore size distribution, thickness, composition of the pore walls, geometry of the pore system, and its topology. Porous hosts provide the guest semiconductor with enhanced stability and versatility in terms of processing, which favors its integration in devices. This article reviews the current progress in the applications of porous materials and structures to improve the performance of LEDs and OLEDs. The use of the porous materials to enhance the optical performance of GaN-/InGaN-/ and AlGaN-based LEDs, porous silicon LEDs, OLEDs are presented. Furthermore, the applications of porous materials for the thermal management of LEDs are discussed.
... In order to take into account mutual interactions between magnetic and thermal phenomena in computer analyses, the electrothermal models of the components contained in the investigated circuit are needed. For transformers, inductors, or solid-state light sources, such models belong to multi-domain models [18]. Electrothermal models can be formulated in the form of detailed or compact models [19,20]. ...
This article proposes a new form of compact electrothermal model of impulse transformers. The proposed model is dedicated for use with SPICE and it is formulated in the network form. It simultaneously takes into account electrical, thermal, and magnetic phenomena occurring in the considered device. Nonlinearity of the core magnetization characteristics and nonlinearity of the heat transfer efficiency are taken into account in this model. The form of the proposed model is shown. Equations of the presented model are given. Experimental verification of the proposed model is performed for selected impulse transformers. Selected results of the performed investigations are presented.
... wifi) are often called smart luminaires but they are rather connected than actually smart-, digitisation and Industry 4.0. After the big transition of LEDification (conversion of incumbent lighting technologies to LED), the re-organised European lighting industry aims to gain back its market shaping role and strengthen its position with smart, knowledge based approaches that build on and extend beyond Industry 4.0 virtual prototyping, for which foundational work was done in the Delphi4LED H2020 ECSEL project [1] [2][3] [4]. ...
... Many studies [30][31][32][33][34][35][36][37] have been devoted to modelling the properties of power LEDs emitting white light, but only some studies [38][39][40] have been devoted to the problem of modelling colour power LEDs. The study in [31] focuses on power LEDs used in display systems, whereas the study in [39] considers the thermal properties of such devices. ...
... This algorithm uses a similar idea of parameter estimation, as described in [55]. The waveforms of self-and transfer transient thermal impedances Zthe(t) measured with the use of the method described in [12,20] are the input data for ESTYM software [37]. This software allows computing the values of parameters Rthe, N, ai and τthi describing the considered electric transient thermal impedances with the formula [18,26] ( ) ...
This paper concerns the problem of modelling electrical, thermal and optical properties of multi-colour power light-emitting diodes (LEDs) situated on a common PCB (Printed Circuit Board). A new form of electro-thermo-optical model of such power LEDs is proposed in the form of a subcircuit for SPICE (Simulation Program with Integrated Circuits Emphasis). With the use of this model, the currents and voltages of the considered devices, their junction temperature and selected radiometric parameters can be calculated, taking into account self-heating phenomena in each LED and mutual thermal couplings between each pair of the considered devices. The form of the formulated model is described, and a manner of parameter estimation is also proposed. The correctness and usefulness of the proposed model are verified experimentally for six power LEDs emitting light of different colours and mounted on an experimental PCB prepared by the producer of the investigated devices. Verification was performed for the investigated diodes operating alone and together. Good agreement between the results of measurements and computations was obtained. It was also proved that the main thermal and optical parameters of the investigated LEDs depend on a dominant wavelength of the emitted light.
... There exists need for standardized compact multi-domain models of LEDs, which need to be implemented by integrating models of other electronic and mechanical components to establish a more unified software-based design for complete LED luminaires as well as their performance analysis. The method suggested by Delphi4LED is to model the multi-domain characteristics of the LEDs such that it can be used at module and system levels Janicki et al., 2019;Poppe et al., 2019). When an accurate thermal model of an LED is used conforming to the actual application environment, performance can be accurately analyzed. ...
The purpose of this work is to understand the theoretical aspects related to the compact multi-domain (Optical, Electrical and Thermal) modeling of light-emitting diodes (LEDs). Prior studies have already deliberated extensively on modeling LEDs in multiple domains with diverse levels of intricacies. The need for standardized compact multi-domain models of light-emitting diodes is emphasized. The multi-domain theory explained in this work enables potential end-users to create their own compact multi-domain models of LEDs and study their working in different operating conditions. The end-users can create their own compact multi-domain models of LEDs either from experimental data or from electronic-datasheets. The procedure for developing mathematical models of LEDs in multiple domains is demonstrated in this work. The reason behind current control of LEDs is explained using multi-domain modeling theory. In what way the problem of thermal runaway is handled by driving LEDs with constant current is discussed using the concepts of multi-domain theory. Unlike prior models, it is proposed to model forward voltage as a junction temperature controlled voltage source. Optical power and heating power are represented as junction temperature controlled current sources. The importance of thermal metrics in assessing aging and performance levels is also discussed. This work also recommends minimum parameters required for developing multi-domain compact models of LEDs.
