Accurate Electro-thermal Model Research Articles

Development of a steady state electrothermal cosimulation model of SiC power modules

Silicon carbide power modules are suitable for high temperature, high voltage and high frequency applications. High operating temperature and high power density bring enormous challenges in chip parallel connection and junction temperature predicting. In this work, a steady state electrothermal cosimulation model is established based on Matlab electrical model and ANSYS thermal analysis model. An experimental study is conducted using a customized single die SiC module. The experimental and numerical results exhibit great agreement, with deviation consistently below 4 %. Then, comprehensive research is conducted to investigate the electrothermal performance of several dies in parallel configuration. The findings unequivocally validate the efficacy of the proposed model in accurately capturing the intricate electrical and thermal characteristics. The proposed numerical model offers a reliable and accurate electrothermal modeling approach for SiC power modules.

An Accurate Electro-Thermal Coupling Model of a GaAs HBT Device under Floating Heat Source Disturbances.

Taking into consideration the inaccurate temperature predictions in traditional thermal models of power devices, we undertook a study on the temperature rise characteristics of heterojunction bipolar transistors (HBTs) with a two-dimensional cross-sectional structure including a sub-collector region. We developed a current-adjusted polynomial electro-thermal coupling model based on investigating floating heat sources. This model was developed using precise simulation data acquired from SILVACO (Santa Clara, CA, USA). Additionally, we utilized COMSOL software (version 5.6) to simulate the temperature distribution within parallel power cells, examining further impacts resulting from thermal coupling. The research findings indicate that the rise in current induces modifications in the local carrier concentration, thereby prompting variations in the local electric field, including changes in the heat source's peak location and intensity. The device's peak temperature exhibits a non-linear trend regulated by the current, revealing an error margin of less than 1.5% in the proposed current-corrected model. At higher current levels, the drift of the heat source leads to an increase in the heat dissipation path and reduces the coupling strength between parallel devices. Experiments were performed on 64 GaAs (gallium arsenide) HBT-based power cells using a QFI infrared imaging system. Compared to the traditional temperature calculation model, the proposed model increased the accuracy by 6.84%, allowing for more precise predictions of transistor peak temperatures in high-power applications.

Accurate Electrothermal Modeling of High Frequency DC–DC Converters With Discrete IGBTs in PLECS Software

In the paper, a novel, improved method of the IGBT junction temperature computations in the PLECS simulation software is presented. The developed method aims at accuracy of the junction temperature computations in PLECS by utilising a more sophisticated model of transistor losses, and by taking into account variability of transistor thermal resistance as a function of its temperature. A detailed description of the proposed method, as well as the parameter estimation procedure is given. The method is verified experimentally for the case of a DC-DC boost converter. Any discrepancies between simulations and measurements are discussed in detail. The proposed method is well suited for accurate electrothermal circuit-level simulations of power electronics converters.

An Improved Physical Model Considering Mirco-Nano Scale Effects for Numerical Simulation of Pirani Vacuum Gauges

An improved physical model was proposed for accurate electrothermal modeling Pirani vacuum gauges (PVG) by accounting for the micro-nano scale effects of heat transfer in sensitive elements and the non-negligible corner heat dissipation from multiple heat sinks. This model is verified by published experimental data and can reveal the influences of geometrical, physical and process parameters, such as device dimensional size, temperature and doping concentrations, on the micro-nano scale heat transfer process, which is a great consideration for microelectromechanical systems (MEMS) PVG designing. Although the model is initially envisaged for MEMS PVG, it could be straightforwardly adopted for the thermal sensors with silicon heaters. Finally, the characteristics of PVG were comprehensively investigated based on the presented model validated by the experimental data. The results show that expanding the area ratio of heat sinks to heater and the thermal resistance ratio of heater to gas is an effective design idea to optimise the maximum sensitivity and central pressure of device.

Accurate Electro-Thermal Computational Model Design and Validation for Inverters of Automotive Electric Drivetrain Applications

This paper proposes the fast and accurate electro-thermal model of the existing Simrod three-phase inverter for an electric vehicle (EV) application. The research focuses on analytical and dynamic electro-thermal models of inverters that can be applied for multi-applications. The optimal design approach of passive filters is presented for the DC and AC sides of the inverter. The analytical model has been established, including a mathematical representation of the inverter and induction motor (IM). The high-fidelity electro-thermal simulation model of an inverter with integrated power loss and thermal model is established. The state-space thermal model (for the IRFS4115PbF device) has been created and incorporated into the MATLAB simulation. The simulation model is then validated with the PLECS software-based thermal model to confirm the accuracy. Indirect field-oriented control (IFOC) is designed for squirrel-cage IM at a maximum power rating of 45 kW and implemented on MATLAB/Simulink. The comparative analysis between the real and simulated results is performed to validate the simulation model at a specific speed, torque, and current. Furthermore, the electro-thermal simulation model has been validated with experimental data using efficiency and temperature comparison. The developed simulation model is beneficial for designing, optimizing, and developing advanced technology-based inverters to achieve higher efficiency at a particular operating range of temperature and power quality. The new European driving cycle (NEDC) speed profile simulation results are demonstrated.

Simple method for the identification of electrical and thermal contact resistances in spark plasma sintering

The electrical and thermal contact resistances are key parameters for obtaining an accurate electro-thermal model of the spark plasma sintering (SPS) process. However, due to the lack of a general expression, these parameters are usually determined empirically. Thus, they are only valid for a specific material and SPS configuration. A simple method based on a limited amount of experiments as well as a new formulation of the electrical and thermal contact resistances are developed. First, the evolution of those resistances is optimized on simple shapes (pellets) experiments. They are then transferred into the electro-thermal simulation of complex shapes configurations, which showed a good agreement between the experimental and computed data.

Analysis of multifinger power HEMTs supported by effective 3-D device electrothermal simulation

The influence of the metallization layer geometry on the electrothermal behavior of the multifinger power high-electron mobility transistors (HEMTs) is studied. The analysis of thermal and electrical behavior is supported by effective 3-D electrothermal device simulation method developed for Synopsys TCAD Sentaurus environment using mixed-mode setup. The proposed methodology allows fast simulation of complex systems from individual semiconductor layers at a frontend up to package and cooling assemblies at a backend. More accurate electrothermal model of power HEMT is proposed and validated by finite element method (FEM) simulations. The analysis points on significant influence of metallization geometry design on electrothermal properties and reliability of the multifinger power HEMTs. The unique identification and visualization of the critical regions allows effective device optimization. Very good comparison between simulation results and experimental data demonstrate validity of the proposed simulation methodology and HEMT structures analysis.

Modeling, Fabrication, and Characterization of Large Carbon Nanotube Interconnects With Negative Temperature Coefficient of the Resistance

One of the most appealing properties of carbon nanotube (CNT) interconnects is the possibility of exhibiting, under certain circumstances, a negative temperature coefficient of the electrical resistance, i.e., a resistance that decreases as temperature increases. In the past, this behavior has been theoretically predicted and experimentally observed, but only for a certain class of CNTs, with short lengths (up to some micrometers) and in a limited range of temperature. This paper demonstrates the possibility of obtaining such a desirable behavior in a larger scale (up to fractions of millimeters). An accurate electrothermal model is used to define the conditions under which a negative derivative of the resistance may be observed. Then, a novel bottom–up technique is proposed to realize the interconnect, by self-assembly of short CNTs. The experimental results of an electrothermal characterization demonstrate the possibility of obtaining a negative temperature coefficient of the resistance and confirm the validity of the theoretical model.

Physical Insight Toward Heat Transport and an Improved Electrothermal Modeling Framework for FinFET Architectures

We report on the thermal failure of fin-shaped field-effect transistor (FinFET) devices under the normal operating condition. Pre- and post failure characteristics are investigated. A detailed physical insight on the lattice heating and heat flux in a 3-D front end of the line and complex back end of line-of a logic circuit network-is given for bulk/silicon-on-insulator (SOI) FinFET and extremely thin SOI devices using 3-D TCAD. Moreover, the self-heating behavior of both the planar and nonplanar devices is compared. Even bulk FinFET shows critical self-heating. Layout, device, and technology design guidelines (based on complex 3-D TCAD) are given for a robust on-chip thermal management. Finally, an improved framework is proposed for an accurate electrothermal modeling of various FinFET device architectures by taking into account all major heat flux paths.

An accurate electro-thermal model for merged SiC PiN Schottky diodes

The paper presents a SiC merged PiN Schottky diode model dedicated to the dynamic as-well-as very accurate static simulation. The model takes into account the temperature dependence of device characteristics and combines in a single model the behaviour typical for bipolar and unipolar devices. The presented electro-thermal simulations of the diode produce accurate results, consistent with the measurements. The dynamic model verification has been also presented on the example of a boost power converter.

A Coupled Electrothermal Model for Planar Transformer Temperature Distribution Computation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Planar transformers (PTs) are of particular interest in switching mode power supplies and, more generally, in power converter design. They provide enhanced performance, compactness, ruggedness, constant quality, and low cost. Their optimum performance can, however, only be obtained through an accurate design which accounts for both electromagnetic and thermal problems. For that reason, this paper proposes a new combined and accurate electrothermal model for PT design. First, the electrical model based on the eddy current equation is defined. A finite element method is applied to obtain the current density distributions. Second, a 1-D thermal model based on Green's function approach is developed to calculate the temperature distribution in the device. The results obtained using the proposed coupled model are compared with measurements. The comparison indicates a relatively good correlation between the results of our model and experimental data. An excellent agreement is however observed at early times. </para>

Evaluating the effects of temperature gradients and currents nonuniformity in on-chip interconnects

The paper provides a compact but accurate electro-thermal model of a long wiring on-chip interconnect embedded in the complex layout of a ULSI digital circuit. The proposed technique takes into account both the effect of temperature gradients over the chip substrate and the interconnect self-heating due to current flow. The proposed compact model is well suited to be interfaced with commercially available CAD tools employed for interconnect parasitic extraction and signal integrity verification. The paper also investigates the electro-thermal effects that arise in a long wiring on-chip interconnect in which current flow is dominated by displacement currents and thus is not uniform along the line.

Accurate electro-thermal model of avalanching junctions subject to ESD currents

A new electro-thermal model of avalanching silicon junctions subject to the abrupt and large currents of electro-static-discharge (ESD) phenomenon is presented. A reliable model of the avalanching junction is the core element for accurate CAD-based analysis of ESD failures.

Thermal networks for electro-thermal analysis of power devices

This work presents a derivation of the equivalent thermal network associated to the distributed heat diffusion process which takes place in an electrical circuit. Precise definition of temperature and dissipated power density for the elementary electrical element are presented. It is shown that these definitions lead to an equivalent thermal network that preserves the physical properties of the original distributed phenomenon. Using these results an accurate electro-thermal network model of a power DMOS is derived.

Three-dimensional modeling of the heat flow into a GaAs substrate. Influence of thermal phenomena on the RF behavior of power HBTs and technological optimization

Using three-dimensional modeling of the heat flow into the substrate, and taking into account the variation of thermal conductivity with temperature, we study the sensitivity of the thermal resistance R TH to parameters such as the substrate thickness, its nature (GaAs, Si, AlN or diamond), the topology of the power source (length and width) or even the power density. Thus, we show that the transfer of active GaAs layers onto a host substrate with a higher thermal conductivity such as Si, AlN or diamond is of greater interest than the thinning of the substrate. We developed an accurate electrothermal model for the AlGaAs/GaAs heterojunction bipolar transistor (HBT) allowing prediction of the static and mainly dynamic (RF) behavior at a high signal operating mode. We show that if the HBT layers are transferred onto a diamond substrate, a 50% gain in RF power can be expected at 10 GHz. Finally, we present the technological solutions investigated for the transfer and the heteroassembly of HBT active layers on substrates better suited for thermal dissipation.