Static Thermal Model Research Articles

Extraction of Compact Static Thermal Model Parameters for SiGe HBTs

In this article, we present and evaluate compact static thermal model parameter extraction techniques for modern silicon germanium heterojunction bipolar transistors (SiGe HBTs). We found that the model implementation of thermal resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {th}}$ </tex-math></inline-formula> ) based on only junction temperature is implicit requiring time-consuming iterative procedure which may lead to potential instabilities. Dedicated extraction techniques are proposed for obtaining compact model-specific <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {th}}$ </tex-math></inline-formula> and its temperature coefficient. The proposed method is primarily validated on SPICE generated synthetic data. Next in order to showcase a compact model-independent verification, we also test the method using detailed thermal simulation from TCAD. Finally, we apply our extraction technique on measured data from fabricated transistors. The results are benchmarked to already obtained nominal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {th}}$ </tex-math></inline-formula> values from the same device family.

Evaluation of the Dependence of the Value of Heat Flux and Temperature on Heat Losses of the Heating Main

Снижение потерь тепла в процессе его доставки до потребителя по трубопроводам является важнейшей задачей теплоснабжающих организаций. Результаты решения этой задачи оказывают серьезное влияние на формирование тарифа на тепло. Цель данной работы - проведение исследования зависимости значений теплового потока двухтрубной тепловой сети канальной прокладки при пролегании подающей и обратной трубы в одном железобетонном коробе от качества теплоизоляции. Основная идея метода состоит в том, что тепловой поток от трубопровода напрямую зависит от температуры протекающей жидкости-теплоносителя, которая может считаться известной, формы и геометрических размеров конструкции и, что немаловажно, от качества изолирующих материалов. Иными словами, при ухудшении качества изоляции тепловой поток, свойственный исправной конструкции, будет неизбежно изменяться, что и позволит в результате применения предложенного метода проводить аудит теплотрассы. Выводы и зависимости, представленные в данной статье, основываются на проведении статического теплового моделирования в математическом пакете ANSYS 17.1. В рамках исследования определяется зависимость температур и теплового потока в точке от общих потерь теплотрассы в атмосферу. Результаты, полученные в данном исследовании, могут быть использованы для проведения аудита теплотрасс за счет измерения теплофизических величин окружающего грунта.

Thermal Modeling of a Claw-Pole Electrical Generator: Steady-State Computation and Identification of Free and Forced Convection Coefficients

The production of heat is a key characteristic of a machine's behavior. Heat sources come mainly from energy losses (electrical in copper, magnetic in iron, aerolic in fans, and mechanical in bearings). Temperature changes can be described owing to thermal conduction, convection, and radiation equations. To understand and design a machine, it is important to construct a dedicated model and to know every physical loss. The aim is therefore to build a static thermal model adapted to the simulation and sizing of claw-pole car alternators. Currently, in cars with internal combustion engines, generators rotors are wire wound, doubly excited with a dc concentrated winding and small permanent magnets, and self-air-cooled with fans. This paper proposes a nodal model with 16 nodes, taking all the heat transfers and space directions into account. The thermal characterization of the machine is permitted by only four physical parameters, varying with the temperature T and the rotating velocity Ω, shown to be sufficient to deduce the model conductances. These properties are as follows: the thermal exchange coefficients due to free and forced convection into the air gap and the cavity, the thermal exchange coefficient due to free superficial convection at the external surface, and the thermal equivalent conductivity within the bearings. The consistency and usefulness of both the model and identifications are checked against numerical studies and measurements.

Converter Structure-Based Power Loss and Static Thermal Modeling of The Press-Pack IGBT Three-Level ANPC VSC Applied to Multi-MW Wind Turbines

Wind turbine converters demand high power density due to nacelle space limitation and high reliability due to high maintenance cost. Depending on the converter structure, the converter thermal performance determines the converter power density and reliability. To estimate the converter thermal performance, the converter structure-based power loss and thermal models are developed in this study for the medium-voltage (MV) three-level active neutral-point-clamped voltage source converter (3L-ANPC-VSC) utilizing 4500 V-1800 A press-pack insulated-gate bipolar transistor-diode pairs and interfacing a 6 MW wind turbine to a MV grid. The switching power loss models are built using the experimental switching power loss data acquired via the double-pulse tests conducted on a full-scale 3L-ANPC-VSC prototype. The converter static thermal model is developed based on the double-sided water-cooled press-pack switches. Via a single-phase test setup with two full-scale 3L-ANPC-VSC legs, the developed power loss and thermal models are validated experimentally. Employing the validated models, the 3L-ANPC-VSC's thermal performance is demonstrated on simulation for a 6 MW wind turbine grid interface. Hence, these converter structure-based models developed and validated in this study are proven to be suitable for the converter power density and reliability studies based on converter thermal performance.

Mechanisms for deuteron production in relativistic nuclear collisions

A variety of mechanisms for deuteron production in relativistic nuclear collisions are considered. These include the coalescence model, the sudden approximation model, and the static thermal model. A new model based on time dependent perturbation theory is presented. A solution of the rate equations for a hydrodynamically expanding fireball suggests that chemical equilibrium might be achieved in central collisions. Emphasis is placed on the physical assumptions of the various models, their limitations, and their subtly different predictions. Of some importance is the effect of impact parameter averaging which, when written in terms of the usual power law relationship, introduces the necessity for measuring various two particle correlation functions to check the self-consistency of these models.NUCLEAR REACTIONS Relativistic heavy ions, models for deuteron production $p\ensuremath{-}n$ correlations.