Special Issue "Thermal and Electro-thermal System Simulation"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Thermal Management".

Deadline for manuscript submissions: closed (1 April 2019).

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Márta Rencz
E-Mail Website
Guest Editor
Department of Electron Devices, Budapest University of Technology and Economics, Magyar tudósok krt. 2, Bld. Q, 3rd floor, Budapest H-1117, Hungary
Interests: thermal investigation of ICs and MEMS; thermal sensors; thermal testing; thermal simulation; thermal model generation; electro-thermal simulation; CPS systems
Special Issues and Collections in MDPI journals
Prof. Lorenzo Codecasa
E-Mail Website
Guest Editor
Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
Interests: electric engineering; electro-thermal circuit modeling and simulation; electromagnetic simulation
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

As a follow-up to the 25th THERMINIC Workshop, held in Stockholm in September 2018, a Special Issue of energies about thermal and multi-physical investigations electronics systems will be edited by Prof. Marta Rencz.

This Special Issue will target the presentation of the newest research results of thermal effects in electronics today, from characterization to through multi-physics simulation to cooling solutions and reliability assessment.

This special issue is not only collecting papers from the 25th THERMINIC Workshop, but also will containing papers from other scholars who interested in this topic. Papers that were presented at THERMINIC must be revised and contain at least 60% new material that has never been presented before.

Prof. Márta Rencz
Prof. Lorenzo Codecasa
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • multi physics simulation and field coupling
  • thermal modelling and investigation of packages
  • thermal interface materials and their characterization
  • thermal management and characterization of electronic components and systems
  • high temperature electronics
  • thermal issues in power electronics
  • thermal issues in solid state lighting
  • CFD modelling and benchmarking
  • thermal performance of interconnects
  • electro-thermal interactions
  • temperature mapping
  • 3D integration and cooling concepts
  • thermo-mechanical reliability
  • lifetime modelling and prediction
  • prognostics and health monitoring

Published Papers (12 papers)

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Research

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Open AccessArticle
Structural Analysis of Power Devices and Assemblies by Thermal Transient Measurements
Energies 2019, 12(14), 2696; https://doi.org/10.3390/en12142696 - 15 Jul 2019
Abstract
Power modules composed of semiconductor dice, thermal interface layers, and cooling mounts can be characterized by thermal transient testing at their actual position (in situ). This paper demonstrates that transient testing enables tracking of changes in material quality and structural details on the [...] Read more.
Power modules composed of semiconductor dice, thermal interface layers, and cooling mounts can be characterized by thermal transient testing at their actual position (in situ). This paper demonstrates that transient testing enables tracking of changes in material quality and structural details on the raw heating or cooling curves. Higher precision can be achieved with the structure function technique where absolute and partial thermal resistance and capacitance values can be used for unambiguous identification of structural elements in a heat conducting path. Measurement techniques are presented to characterize the self-heating of a die and heat transfer between dice. Change of the thermal interface material layers in assembly during test sequences is also highlighted by the structure function concept. The power distribution between dice and wiring is analyzed by the newly introduced “accordion” principle. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Luminaire Digital Design Flow with Multi-Domain Digital Twins of LEDs
Energies 2019, 12(12), 2389; https://doi.org/10.3390/en12122389 - 21 Jun 2019
Cited by 3
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Reliability Investigation of a Carbon Nanotube Array Thermal Interface Material
Energies 2019, 12(11), 2080; https://doi.org/10.3390/en12112080 - 31 May 2019
Abstract
As feature density increases within microelectronics, so does the dissipated power density, which puts an increased demand on thermal management. Thermal interface materials (TIMs) are used at the interface between contacting surfaces to reduce the thermal resistance, and is a critical component within [...] Read more.
As feature density increases within microelectronics, so does the dissipated power density, which puts an increased demand on thermal management. Thermal interface materials (TIMs) are used at the interface between contacting surfaces to reduce the thermal resistance, and is a critical component within many electronics systems. Arrays of carbon nanotubes (CNTs) have gained significant interest for application as TIMs, due to the high thermal conductivity, no internal thermal contact resistances and an excellent conformability. While studies show excellent thermal performance, there has to date been no investigation into the reliability of CNT array TIMs. In this study, CNT array TIMs bonded with polymer to close a Si-Cu interface were subjected to thermal cycling. Thermal interface resistance measurements showed a large degradation of the thermal performance of the interface within the first 100 cycles. More detailed thermal investigation of the interface components showed that the connection between CNTs and catalyst substrate degrades during thermal cycling even in the absence of thermal expansion mismatch, and the nature of this degradation was further analyzed using X-ray photoelectron spectroscopy. This study indicates that the reliability will be an important consideration for further development and commercialization of CNT array TIMs. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Influence of Power Losses in the Inductor Core on Characteristics of Selected DC–DC Converters
Energies 2019, 12(10), 1991; https://doi.org/10.3390/en12101991 - 24 May 2019
Abstract
The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is [...] Read more.
The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is used. Correctness of this model is verified experimentally for three different magnetic materials. Computations are performed with the use of this model and the Excel software for inductors including cores made of ferrite, powdered iron, and nanocrystalline material in a wide range of load resistance, as well as input voltage of both the considered converters operating at different values of switching frequency. The obtained computation results show that power losses in the inductor core and watt-hour efficiency of converters strongly depend on the material used to make this core, in addition to the input voltage and parameters of the control signal and load resistance of the considered converters. The obtained results of watt-hour efficiency of the considered direct current (DC)–DC converters show that it changes up to 30 times in the considered ranges of the mentioned factors. In turn, in the same operating conditions, values of power losses in the considered cores change from a fraction of a watt to tens of watts. The paper also considers the issue of which material should be used to construct the inductor core in order to obtain the highest value of watt-hour efficiency at selected operation conditions of the considered converters. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Multi-Domain Modelling of LEDs for Supporting Virtual Prototyping of Luminaires
Energies 2019, 12(10), 1909; https://doi.org/10.3390/en12101909 - 18 May 2019
Cited by 9
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Modelling a Switching Process of IGBTs with Influence of Temperature Taken into Account
Energies 2019, 12(10), 1894; https://doi.org/10.3390/en12101894 - 18 May 2019
Cited by 1
Abstract
In this article the problem of modelling a switching process of Insulated Gate Bipolar Transistors (IGBTs) in the SPICE software is considered. The new form of the considered transistor model is presented. The model includes controlled voltage and current sources, resistors and voltage [...] Read more.
In this article the problem of modelling a switching process of Insulated Gate Bipolar Transistors (IGBTs) in the SPICE software is considered. The new form of the considered transistor model is presented. The model includes controlled voltage and current sources, resistors and voltage sources. In the model, influence of temperature on dc and dynamic characteristics of the IGBT is taken into account. A detailed description of the dynamic part of this model is included in the article and some results of experimental verification are shown. Verification is performed for a transistor IRG4PC40UD by International Rectifier. The presented results of computations and measurements show clearly influence of temperature on on-time and off-time, and additionally switching energy losses are observed. Moreover, the results of investigations performed with the use of the new model are compared to the results of computations performed with classical models of the considered device given in the literature. It is proved that the new model makes it possible to obtain a better match to the results of measurements than the considered models described in the literature. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs
Energies 2019, 12(10), 1860; https://doi.org/10.3390/en12101860 - 15 May 2019
Cited by 2
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Parametric Compact Thermal Models of Power LEDs
Energies 2019, 12(9), 1724; https://doi.org/10.3390/en12091724 - 07 May 2019
Abstract
Light-emitting diodes are nowadays the most dynamically developing type of light sources. Considering that temperature is the main factor affecting the electrical and lighting parameters of these devices, thermal models are essential subcomponents of the multidomain models commonly used for simulation of their [...] Read more.
Light-emitting diodes are nowadays the most dynamically developing type of light sources. Considering that temperature is the main factor affecting the electrical and lighting parameters of these devices, thermal models are essential subcomponents of the multidomain models commonly used for simulation of their operation. The authors investigated white power light-emitting diodes soldered to Metal Core Printed Circuit Boards (MCPCBs). The tested devices were placed in a light-tight box on a cold plate and their cooling curves were registered for different diode heating current values and various preset cold plate temperatures. These data allowed the computation of optical and real heating power values and consequently the generation of compact thermal models in the form of Foster and Cauer RC ladders. This also rendered possible the analysis of the influence of the considered factors on the compact model element values and their parametrization. The resulting models yield accurate values of diode junction temperature in most realistic operating conditions and they can be easily included in multidomain compact models of power light emitting diodes. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Extraction of Boundary Condition Independent Dynamic Compact Thermal Models of LEDs—A Delphi4LED Methodology
Energies 2019, 12(9), 1628; https://doi.org/10.3390/en12091628 - 29 Apr 2019
Cited by 6
Abstract
Multi-domain electro-thermal-optical models of LEDs are required so that their thermal and optical behavior may be predicted during a luminaire design process. Today, no standardized approach exists for the extraction of such models. Therefore, models are not readily provided by LED suppliers to [...] Read more.
Multi-domain electro-thermal-optical models of LEDs are required so that their thermal and optical behavior may be predicted during a luminaire design process. Today, no standardized approach exists for the extraction of such models. Therefore, models are not readily provided by LED suppliers to end-users. This results in designers of LED-based luminaires wasting time on LED characterization and ad hoc model extraction themselves. The Delphi4LED project aims to address these deficiencies by identifying standardizable methodologies to extract both electro-optical and thermal compact models of LEDs that together can be used in a multi-domain simulation context. This article describes a methodology to extract compact thermal models of LEDs that are dynamic, in that they accommodate transient thermal effects, and are boundary condition-independent, in that their accuracy is independent of their thermal operating environment. Such models are achieved by first proposing an equivalent thermal nodal network topology. The thermal resistances and capacitances of that network are identified by means of optimization so that the transient thermal response of the network matches that of either an equivalent calibrated 3D thermal model or a transient thermal measurement of a physical sample. The accuracy of the thermal network is then verified by comparing the thermal compact model with a 3D detailed model, which predicts thermal responses within a 3D system-level model. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
TRAC: A Thermal Resistance Advanced Calculator for Electronic Packages
Energies 2019, 12(6), 1050; https://doi.org/10.3390/en12061050 - 19 Mar 2019
Cited by 2
Abstract
This paper presents a novel simulation tool named thermal resistance advanced calculator (TRAC). Such a tool allows the straightforward definition of a parametric detailed thermal model of electronic packages with Manhattan geometry, in which the key geometrical details and thermal properties can vary [...] Read more.
This paper presents a novel simulation tool named thermal resistance advanced calculator (TRAC). Such a tool allows the straightforward definition of a parametric detailed thermal model of electronic packages with Manhattan geometry, in which the key geometrical details and thermal properties can vary in a chosen set. Additionally, it can apply a novel model-order reduction-based approach for the automatic and fast extraction of a parametric compact thermal model of such packages. Furthermore, it is suited to automatically determine the joint electron device engineering council (JEDEC) thermal metrics for any choice of parameters in a negligible amount of time. The tool was validated through the analysis of two families of quad flat packages. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Open AccessArticle
Structure Function Analysis of Temperature-Dependent Thermal Properties of Nm-Thin Nb2O5
Energies 2019, 12(4), 610; https://doi.org/10.3390/en12040610 - 15 Feb 2019
Abstract
A 166-nm-thick amorphous Niobium pentoxide layer (Nb2O5) on a silicon substrate was investigated by using time domain thermoreflectance at ambient temperatures from 25 °C to 500 °C. In the time domain thermoreflectance measurements, thermal transients with a time resolution [...] Read more.
A 166-nm-thick amorphous Niobium pentoxide layer (Nb2O5) on a silicon substrate was investigated by using time domain thermoreflectance at ambient temperatures from 25 °C to 500 °C. In the time domain thermoreflectance measurements, thermal transients with a time resolution in (sub-)nanoseconds can be obtained by a pump-probe laser technique. The analysis of the thermal transient was carried out via the established analytical approach, but also by a numerical approach. The analytical approach showed a thermal diffusivity and thermal conductivity from 0.43 mm2/s to 0.74 mm2/s and from 1.0 W/mK to 2.3 W/mK, respectively to temperature. The used numerical approach was the structure function approach to map the measured heat path in terms of a RthCth-network. The structure function showed a decrease of Rth with increasing temperature according to the increasing thermal conductivity of Nb2O5. The combination of both approaches contributes to an in-depth thermal analysis of Nb2O5 film. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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Review

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Open AccessReview
Thermal Management of High-Power Density Electric Motors for Electrification of Aviation and Beyond
Energies 2019, 12(19), 3594; https://doi.org/10.3390/en12193594 - 20 Sep 2019
Cited by 1
Abstract
Enhanced cooling, coupled with novel designs and packaging of semiconductors, has revolutionized communications, computing, lighting, and electric power conversion. It is time for a similar revolution that will unleash the potential of electrified propulsion technologies to drive improvements in fuel-to-propulsion efficiency, emission reduction, [...] Read more.
Enhanced cooling, coupled with novel designs and packaging of semiconductors, has revolutionized communications, computing, lighting, and electric power conversion. It is time for a similar revolution that will unleash the potential of electrified propulsion technologies to drive improvements in fuel-to-propulsion efficiency, emission reduction, and increased power and torque densities for aviation and beyond. High efficiency and high specific power (kW/kg) electric motors are a key enabler for future electrification of aviation. To improve cooling of emerging synchronous machines, and to realize performance and cost metrics of next-generation electric motors, electromagnetic and thermomechanical co-design can be enabled by innovative design topologies, materials, and manufacturing techniques. This paper focuses on the most recent progress in thermal management of electric motors with particular focus on electric motors of significance to aviation propulsion. Full article
(This article belongs to the Special Issue Thermal and Electro-thermal System Simulation) Printed Edition available
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