Electrothermal Analysis Research Articles

Estimate the Meaning-Time-To-Failure of LED driver using Numerical simulation

The Meaning-Time-To-Failure (MTTP), also known as Electromigration Analysis is an estimation of product life. Light-Emitting Diodes (LEDs) are usually driven by constant current switched-mode power supplies, which are invented early than LEDs for lighting applications. While LEDs themselves are extremely reliable and have a long lifetime, the electronic LED drivers in experiment usually fail due to overheating causing Printed Circuit Boards (PCBs) explosion, inability provide current/voltage input to the LEDs over their whole lifetime. This paper proposes a numerical simulation method to predict fault location on PCB of LED driver based on 2-way coupling electro-thermal multiphysic analysis, then applies the analytic models to calculate the time to failure of the points on PCB of LED drivers. The procedures can be applied to assist managers in assessing risk and making LED-based lighting system reliability decisions.

Harmonic-based expected life estimation of electric arc furnace's high voltage polymeric insulated cables based on electro-thermal stresses considering sheath bonding methods and transient over-voltages

The life estimation of power components, such as XLPE cables, has recently received a great deal of attention. However, there is a gap about introducing a comprehensive harmonic-based life estimation of electric arc furnaces (EAFs)’s power cables. Because of the EAF cyclic operation and its current harmonics, the convectional life estimation method might not be adequately precise. This article aims to fill such a knowledge gap by developing a harmonic-based life estimation of EAf's power cables considering free and non-forced convection, over-voltages due to switchings and single line to ground (SLG) faults, and sheat bonding methods. The finite element method (FEM)-based electro-thermal analysis is used in the proposed study to estimate the loss of life (LOL) of EAF's power cables accurately. In this research, the COMSOL Multiphysics software has been used to implement the electro-thermal analysis of an actual test system. Electro-thermal analysis’ results are compared to actual measurements to validate the simulations. The comparative results infer that about 30% inaccuracy occurs in LOL estimation of EAF's XLPE cable due to neglecting the electro-thermal stresses of current harmonics. The obtained results also highlight the impacts of the sheath bonding method on the EAF cables’ LOL.

Analysis of Transient Surge Current Mechanism in SiC MPS Diode With the Transition Region

In this work, Sentaurus TCAD was used to study the transient surge current mechanism of the 4H-SiC merged pin and schottky (MPS) diode. For the first time, a structure combining multicells with transition region was used to analyze the transient surge current mechanism of the MPS diode. The electrothermal simulation analysis of the surge characteristics of the MPS diode is carried out. Internal carrier distribution and lattice temperature in the surge current transient process of the device are mainly studied. The simulation results show that the hole current distribution and the electron current distribution in the MPS diode are not uniform. In the transient process of surge current, the transition region first enters the bipolar conduction mode, and then, the cells in the active region enter the bipolar conduction mode in the order from outside (close to transition region) to inside. The voltage-time (V-t), maximum temperature-time ( $T_{max}$ -t), and I-V curves of MPS diode in surge current events are obtained by simulation. Combined with the current density distribution diagram, the device behavior of multiple critical time nodes is analyzed in detail, and a reasonable explanation is given. In addition, the influence of different transition region contact types on the internal current distribution of the MPS diode is studied, and the simulation results are reasonably explained.

Robustness study of bandpass NGD behavior of ring-stub microstrip circuit under temperature variation

Abstract This paper explores an original study of bandpass (BP) negative group delay (NGD) robustness applied to the ring-stub passive circuit. The proof of concept (PoC) circuit is constituted by a ring associated with the open-end stub implemented in microstrip technology. An innovative experimental setup of a temperature room containing the NGD PoC connected to a vector network analyzer is described. Then, the electrothermal data of S-parameters are measured by varying the ambient or room temperature range from 20 to 60°C, i.e. 40°C maximal variation. The empirical results of the group delay (GD), transmission and reflection coefficient mappings versus the couple (temperature, frequency) highlight how the temperature affects the BP NGD responses. An innovative electrothermal calibration technique by taking into account the interconnection cable influence is developed. The electrothermal robustness analysis is carried out by variations of the NGD center frequency, cut-off frequencies and value in function of the temperature.

Transient Electro-Thermal Coupled Modeling of Three-Phase Power MOSFET Inverter during Load Cycles.

This study introduces an effective and efficient dynamic electro-thermal coupling analysis (ETCA) approach to explore the electro-thermal behavior of a three-phase power metal–oxide–semiconductor field-effect transistor (MOSFET) inverter for brushless direct current motor drive under natural and forced convection during a six-step operation. This coupling analysis integrates three-dimensional electromagnetic simulation for parasitic parameter extraction, simplified equivalent circuit simulation for power loss calculation, and a compact Foster thermal network model for junction temperature prediction, constructed through parametric transient computational fluid dynamics (CFD) thermal analysis. In the proposed ETCA approach, the interactions between the junction temperature and the power losses (conduction and switching losses) and between the parasitics and the switching transients and power losses are all accounted for. The proposed Foster thermal network model and ETCA approach are validated with the CFD thermal analysis and the standard ETCA approach, respectively. The analysis results demonstrate how the proposed models can be used as an effective and efficient means of analysis to characterize the system-level electro-thermal performance of a three-phase bridge inverter.

A Proposal of Vertical MOSFET and Electrothermal Analysis for Monolithic 3-D ICs

In this paper, an innovative vertical MOSFET based on through-oxide via (TOV) technology is proposed for silicon-on-insulator (SOI)-based monolithic 3-D ICs. The proposed vertical MOSFET is investigated numerically. It was found that SOI can effectively reduce the parasitic capacitance, leakage current, power consumption, as well as suppress the pulse current interference of the substrate. The simulated results indicate that the proposed MOSFET possesses excellent characteristics in saturation current over 1500 μA, sub-threshold swing of 69 mV/dec, and on/off current ratio of 1.28 × 1011. Moreover, as temperature is a critical factor for the performance degradation of semiconductor devices, electrothermal simulations are conducted to predict the influence of the self-heating effect on device characteristics. The results show that device characteristics slightly deteriorate, but can still acceptable in their applications.

Design, Simulation, and Fabrication of a Copper-Chrome-Based Glass Heater Integrated into a PMMA Microfluidic System.

In this paper, the development of a copper–chrome-based glass microheater and its integration into a Polymethylmethacrylate (PMMA) microfluidic system are presented. The process highlights the importance of an appropriate characterization, taking advantage of computer-simulated physical methods in the heat transfer process. The presented system architecture allows the integration for the development of a thermal flow sensor, in which the fluid flows through a 1 mm width × 1 mm length microchannel across a 5 mm width × 13 mm length heating surface. Using an electrothermal analysis, based on a simulation and design process, the surface heating behavior curve was analyzed to choose a heating reference point, primarily used to control the temperature point within the fluidic microsystem. The heater was characterized using the theory of electrical instrumentation, with a 7.22% error for the heating characterization and a 5.42% error for the power consumption, measured at 0.69 W at a temperature of 70 °C. Further tests, at a temperature of 115 °C, were used to observe the effects of the heat transfer through convection on the fluid and the heater surface for different flow rates, which can be used for the development of thermal flowmeters using the configuration presented in this work.

Electrothermal Analysis of the Charge–Discharge Related Energy Loss of the Output Capacitance in OFF-State Superjunction MOSFETs

The charge-discharge-related loss of the output capacitance ( C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> ) in OFF-state Superjunction (SJ) MOSFETs, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DISS</sub> , is a new source of energy loss limiting the frequency of soft-switched SJ MOSFETs. This article studies the electrothermal effect in C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> during the charging and discharging processes with the help of numerical electrothermal simulations. The results show that energy is lost during both charging and discharging processes, mainly contributed by Joule heat that is caused by the movement of carriers in lightly doped drift regions. The fluctuant doping profile in a SJ MOSFET constructed with the multi-implant multi-epitaxy technology compresses the width of the path of charging and discharging currents at concentration valleys and causes high-current density. Then, its <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DISS</sub> is larger than that of the SJ MOSFET constructed with the trench-filling epitaxial growth technology. For an advanced device with a smaller cell-pitch, the width of the current path becomes narrower. Then, the current density decreases, and so does its <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DISS</sub> .

Electrothermal Stress Analysis and Lifetime Evaluation of DC-Link Capacitor Banks in the Railway Traction Drive System

In the railway traction drive system, the reliability of DC-link capacitor banks faces enormous challenges due to the multioperation conditions, the complex physical structures, and the safe operation requirements. Considering these issues, this article proposes a reliability evaluation method of the DC-link capacitors banks to provide a guideline for preventive maintenance in the traction drive system. In the electrothermal stress analysis, different from the conventional methods, the dynamic power loss profile is obtained by the sliding-window discrete Fourier transform (DFT), and the equivalent series resistance is fit by the neural network. Afterward, a bidirectional thermal model is established to estimate the thermal stress under the dynamic power losses, considering the impact of thermal capacity, thermal coupling, and air-cooling heat dissipation. In addition, according to the stability analysis and the rated temperature limitation, an end-of-lifetime standard that meets the safe operation requirement of the train is first proposed, thereby evaluating the lifetime bottleneck of the DC-link capacitor banks. The evaluation results can provide a reference to use the low-cost on-condition maintenance instead of scheduled maintenance in the railway traction drive system. Furthermore, a prototype experiment is performed to verify the effectiveness of the electrothermal stress model.

A Gas Sensor Design and Heat Transfer Simulation with ZnO and TiO2 Sensing Layers

Micro Electro-Mechanical System (MEMS) based devices offer innovative approaches in sensor technologies with the advantages of high efficiency and miniaturization. The most important stage in the development of new generation MEMS-based devices is the design and optimization stage. However, device design and optimization processes are developed in a laboratory by empirical approaches. This causes time loss and creates an unnecessary waste of resources. In this study, it is aimed to design and analyze two gas sensors based on ZnO and TiO2 sensing layers. Electro-thermal analysis of the sensor structure was carried out at room temperature and high temperature (294,15K-573,15K) and heat transfer parameters were compared. According to the simulation results, it is obtained that, as the applied temperature increases to the sensor, the temperature over the sensing layer increases linearly. It is compatible with the literature. The temperature on the ZnO surface increases to three times the TiO2 surface temperature. The heat transfer results obtained will be used as a guide for device design and optimization in future works. In this way, as a result of numerical analysis, a MEMS-based device will be produced with high accuracy. Thus, time and resources will be saved.

Phase-change memory electro-thermal analysis and engineering thanks to enhanced thermal confinement

In this paper we compare the performances of SiN with respect to an optimized SiC encapsulation in Wall based Phase-Change Memory (PCM) integrating a Ge-rich Ge-Sb-Te alloy (GGST) suitable for high temperature stability in automotive applications. Thanks to the electrical characterization of 4 kb arrays, 3D electro-thermal simulations and TEM analyses performed on programmed devices, we demonstrate the higher programming efficiency in SiC-based PCM devices, thanks to the lower thermal conductivity of the optimized encapsulation. Indeed, the uniform temperature profile achieved in the active layer of SiC encapsulated PCM leads to a retention of one hour at 250 °C. A theoretical model is here proposed to describe the electro-thermal behavior of the device, linking the electrical properties, such as the resistance as a function of current characteristics, to the thermal conductivity of the materials that constitute the device. Finally, thanks to our findings, we provide some guidelines to achieve drastic current reduction via the thermal engineering of the next generation PCM technology.

Power Withstanding Capability and Transient Temperature of Carbon Nanotube-Based Nano Electrical Interconnects

This paper exhibits the electrothermal modelling and evaluation of Carbon Nanotube (CNT) based electrical interconnects for electronic devices. The continuum model of the CNT is considered and the temperature across interconnect is predicted for the given power. Finite element modelling software COMSOL Multiphysics is used to carry out the simulations. The results are compared with Al and Cu interconnects. An electrothermal analysis is also carried out to obtain the temperature for the given power for Single-Walled CNT, Double-Walled CNT, Triple-Walled CNT, and Multi-Walled CNT. Results show that the CNT interconnects performs better when compared to Al and Cu interconnects. The power withstanding capability of CNT is 68.75 times more than Al and 32.35 times more than Cu. Based on the transient analysis, the time taken by the CNT interconnects to reach a steady temperature is obtained as 0.007 ns. On the application of power, Cu and Al interconnects takes 0.1 ns to reach the steady-state temperature. The nanostructured CNT based electrical interconnects would play a considerable role in replacing Cu and Al electrical interconnect applications for micro and nanoelectronic devices.

Towards the prospection of an optimal thermal response of ZnO surge arrester in HV power system

In order to understand the thermal and electrical properties of surge arrester under standard climatic conditions, it would be useful to evaluate the heating progression in its different elements. These are constituted of heterogeneous materials, which have physical and electrical nonlinear properties along the surge arrester. Temperature predicting solutions for zinc oxide ceramic blocks provide fundamental elements of the electrothermal material characteristics in view of the lifetime estimation. Electrothermal phenomenon analysis of surge arresters is based on empirically-determined parameter models, using finite element method (FEM) simulated on COMSOL Multiphysics software which is a more precise approach compared to the existing models. In this paper, the behavioural model has been developed to study the surge arresters in both cases: the steady state and overvoltage state (lightning). Previous published works validate the first simulation results. This work is therefore extended to consider other operating states, which illustrate the dependence of the type of surge on the amplitudes and durations of electrothermal phenomena.

Electro–Thermal–Mechanical Coupled Analysis on Two High-Current Composite Umbilical Cable Cross Sections

Abstract A new type of umbilical cable named “high-current composite umbilical cable” is composed of electronic cables, optical cables, steel tubes, and structural strengthening components. It can be regarded as a key piece of industrial equipment in subsea production systems that provide control functions, high electric current, and hydraulic remote transmission. When it is oriented at a power supply with a relatively high rated current, power transmission will produce a lot of heat. Then, the cross-sectional temperature increases, which affects the performances of its material and mechanical responses. Therefore, electro–thermal–mechanical coupled analysis is critical for the cross-sectional design of the high-current composite umbilical cable. Accordingly, a multi-physics coupled analysis was performed based on two typical umbilical cable cross sections. Finite element models were established and subjected to electro–thermal analysis to obtain a temperature distribution of the two sections at different current capacities. Based on results of temperature field analysis, the section models were subjected to thermo–mechanical analysis. The results of the two types of analyses are compared and differences are discussed, which illustrate the multi-physics coupled effect cannot be neglected. The armored layers will relatively reduce the heat dissipation performance, but compared with the umbilical cable model without the armored layers, the model with double-armored layers is less affected by temperature, so its capacity of resistance external pressure is relatively better. The proposed coupled analysis methodology provides a new guidance for the design of the high-current composite umbilical cables.

Theoretical Analysis of Electric Heating Field and Insulation Accident of High Voltage AC Basin Insulator

Basin insulator is widely used in GIS equipment. It is an important insulating part to realize electrical isolation between central conductor and grounding flange. In this paper, the insulation properties of the materials used for the basin insulator are analyzed experimentally, and the distribution of the electric field of the basin insulator is obtained through the electro-thermal coupling analysis process, and the relationship between the hottest spot temperature and the current carrying capacity is calculated. The heating curve of the basin insulator is obtained by using the theoretical model, and the basin insulation accident is analyzed by using the curve. Considering that the basin insulator is in the SF6 gas atmosphere for a long time, the local temperature rise caused by overheating fault of the basin insulator, and then the variation law of SF6 gas pressure and density caused by the overheating fault of the basin insulator are theoretically analyzed in this paper. Research shows: there is significant non-linear relationship between the insulation performance parameters of the basin body and the temperature. The eddy current field and harmonic field analysis method based on the finite element method can effectively calculate the heating of the center guide rod and the basin body under the power frequency condition. The maximum electric field intensity appears at the interface between the basin and the center conductor, with the value of 6.033kV/mm. The maximum temperature is near center conductor side of the basin, with value of 0.033kV/mm. When the current carrying capacity is higher than 1.5 times of the rated value, the thermal breakdown phenomenon of sudden temperature rise occurs. The calculation process of thermal electric coupling proposed in this paper provides way for verification of thermal electric performance of basin insulator design scheme, and also provides theoretical guidance for its on-site maintenance and accident analysis.

Electrothermal analysis of radiofrequency tissue ablation with injectable flexible electrodes considering bio-heat transfer

Flexible electrodes have been widely focused on in recent years due to their special mechanical properties, which can be directly integrated onto human soft tissues to actively take effects on human body or passively monitor human vital signs. These flexible electrodes provide a new routine to realize clinical treatment of accurate thermal ablation in the biological tissues via radiofrequency ablation (RFA). Meanwhile, accurately controlling of thermal field is very significant for the thermal ablation in the clinical therapeutics to prevent the healthy tissue from excessive burning. In this paper, both one-dimensional and two-dimensional axisymmetric analytical models for the electrothermal analysis of radiofrequency ablation considering bio-heat transfer are established, which are verified by finite element analysis (FEA) and in vitro experiments on pig skins. In the model, the electrical field and thermal field are both derived analytically to accurately predict the temperature rise in the biological tissues. Furthermore, parameters, such as the blood flow convection in living tissues and thickness of tissue, have obvious effects on the thermal field in the tissues. They may pave the theoretical foundation and provide guidance of RFA with flexible electrodes in the future.

Intelligent long-term performance analysis in power electronics systems

This paper proposes a long-term performance indicator for power electronic converters based on their reliability. The converter reliability is represented by the proposed constant lifetime curves, which have been developed using Artificial Neural Network (ANN) under different operating conditions. Unlike the state-of-the-art theoretical reliability modeling approaches, which employ detailed electro-thermal characteristics and lifetime models of converter components, the proposed method provides a nonparametric surrogate model of the converter based on limited non-linear data from theoretical reliability analysis. The proposed approach can quickly predict the converter lifetime under given operating conditions without a further need for extended, time-consuming electro-thermal analysis. Moreover, the proposed lifetime curves can present the long-term performance of converters facilitating optimal system-level design for reliability, reliable operation and maintenance planning in power electronic systems. Numerical case studies evaluate the effectiveness of the proposed reliability modeling approach.

Optimized Design of Embedded Air Coil for Small Satellites with Various Dimensions

Active attitude control systems using a novel six-layer electromagnetic embedded printed air coil for small satellites with various dimensions are presented in this paper. The proposed designs are optimized in terms of available area, generated torque, power dissipation, and generated magnetic dipole moment. The designed printed air coils are the best choice for small satellites’ attitude stabilization in terms of their modularity, reconfigurability, lower cost, lesser space occupation, and low mass. The printed air coil is designed and analyzed for three small satellites with dimensions 10, 13, and . The design is implemented with commercial off-the-shelf microdevices that are inexpensive, reliable, and easily accessible. The printed air coil is integrated in internal layers of printed circuit board, which does not require additional space on the spacecraft. The proposed air coil with additional configurability features (, hybrid) provides more flexibility to the design aspects by changing the arrangement through the onboard processor according to mission requirements. Electrothermal analysis of the air coil module is done to keep the thermals in check and validate its feasibility. Time-varying rotational operation of nanosatellites is performed to test the rotation time for spin-stabilized satellites. Significant performance parameters like generated magnetic moment, resultant torque, and power dissipation are evaluated and compared with the already commercial state-of-the-art.

Three-Dimensional Electro-Thermal Analysis of a New Type Current Transformer Design for Power Distribution Networks

In recent years, the new type design of current transformer with bushing structure has been widely used in the distribution network system due to its advantages of miniaturization, high mechanical strength, maintenance-free, safety and environmental protection. The internal temperature field distribution is an important characteristic parameter to characterize the thermal insulation and aging performance of the transformer, and the internal temperature field distribution is mainly derived from the joule heat generated by the primary side guide rod after flowing through the current. Since the electric environment is a transient field and the thermal environment changes slowly with time as a steady field under the actual conditions, it is more complex and necessary to study the electrothermal coupling field of current transformer (CT). In this paper, a 3D simulation model of a new type design of current transformer for distribution network based on electric-thermal coupling is established by using finite element method (FEM) software. Considering that the actual thermal conduction process of CT is mainly by conduction, convection and radiation, three different kinds of boundary conditions such as solid heat transfer boundary condition, heat convection boundary condition and surface radiation boundary condition are applied to the CT. Through the model created above, the temperature rise process and the distribution characteristics of temperature gradient of the inner conductor under different current, different ambient temperatures and different core diameters conditions are studied. Meanwhile, the hottest temperature and the maximum temperature gradient difference are calculated. According to this, the position of weak insulation of the transformer is determined. The research results can provide a reference for the factory production of new type design of current transformer.

Electro-thermal comprehensive analysis method for defective bushings in HVDC converter transformer valve-side under multiple-frequency voltage and current harmonics

The insulation failure mechanism of the resin impregnated paper (RIP) valve-side bushings of HVDC converter transformer under high ambient temperature and strong electromagnetic field conditions is explored in this study via a novel electro-thermal comprehensive analysis method. Considering that the bushings are operating under Multiple-Frequency Voltage and Current Harmonics, a superposition analysis method is established for voltage and current with five frequencies based on a Fourier spectrum analysis of the rated voltage waveform and full-load current waveform. Calculation methods for the heat loss, temperature field, and electric field of RIP bushings at the converter transformer valve-side are then established under two defect conditions: (1) overheating defect caused by an abnormal spring contact at the copper-aluminium conductive tube transition joint and (2) electric potential suspension caused by disconnection between the outmost condenser’s foil layer and grounded flange. An overheating defect in a valve-side bushing with spring contact at the conductive tube is successfully identified by the proposed method to prove its effectiveness. This method can be used to optimize bushing insulation and current-carrying structures as well as to diagnose insulation failures in RIP valve-side bushings.