System and Component Level Risk Assessment for SiC MOSFET Based Inverter for Traction Application

2020 ◽  
Author(s):  
Bakhtiyar Mohammad Nafis ◽  
Mohammad Mahmud ◽  
Zhongjing Wang ◽  
Yuheng Wu ◽  
David Huitink ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Environmental Protection Agency ◽  
Economic Cost ◽  
Electronic System ◽  
Temperature Limit ◽  
Component Level ◽  
Damage And Failure ◽  
Failure Risk ◽  
Power Testing ◽  
Mission Profile

Abstract Monitoring and predicting temperatures at critical locations of a power electronic system is important for safety, reliability and efficiency. As the market share of vehicles with electric powertrains continue to increase, there is also an important economic cost of failing electronic components. For inverters present in such a drive system, exceeding the temperature limit for certain critical components, such as DC-link capacitors and Silicon carbide MOSFETs, can lead to failure of the system. In such an application, extracting the temperatures using sensors from locations such as dies and capacitors require expensive modifications and poses technical challenges. It is therefore necessary to create a thermal model for the inverter system to estimate the temperature at various components in order to ensure operation within temperature limits. The model approach is also suitable for predicting the effect on the component temperature and reliability of boundary conditions such as coolant, ambient temperature and mission profile. This study assesses the reliability of a 250 kW liquid cooled inverter system designed for traction application. The critical failure areas are the DC-link capacitors, and the SiC MOSFET dies which are rated at 175 degrees C. The system is modeled as a compact system by reasonably considering each component as a lumped capacitance and estimating the thermal resistance using physical dimensions. Results from the model are then compared against experimental data from constant power testing, and good agreement is observed for the cold plate and gate driver temperatures. With the model fidelity established, the model is then used to implement drive cycles from the Environmental Protection Agency for nonroad applications. The resulting temperature profile for each component are a series of temperature peaks and troughs that contribute to damage and failure. Rainflow counting algorithm is then used to quantify the damage per mini-cycles, and used to estimate the predicted life for each component based on their manufacturer provided reliability qualification and the mission profile is executed on the test bench for validation. The results are then used to generate a system risk matrix that relates the failure risk associated with a certain mission profile and the cooling scheme. It therefore demonstrates that an automotive inverter with SiC switching devices can be credibly assessed for failure risk using a compact model that is independent of boundary conditions, in combination with established reliability correlations and techniques.

System and Component Level Risk Assessment for SiC MOSFET Based Inverter for Traction Application at High Coolant Temperatures and Off-Road Mission Profile

2021 ◽  
Vol 144 (2) ◽  
Author(s):  
Bakhtiyar Mohammad Nafis ◽  
Mohammad Mahmud ◽  
Zhongjing Wang ◽  
Yuheng Wu ◽  
David Huitink ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Environmental Protection Agency ◽  
Economic Cost ◽  
Electronic System ◽  
Temperature Limit ◽  
Component Level ◽  
Damage And Failure ◽  
Failure Risk ◽  
Power Testing ◽  
Mission Profile

Abstract Monitoring and predicting temperatures at critical locations of a power electronic system is important for safety, reliability, and efficiency. As the market share of vehicles with electric powertrains continues to increase, there is also an important economic cost of failing electronic components. For inverters present in such a drive system, exceeding the temperature limit for certain critical components, such as DC-link capacitors and Silicon carbide MOSFETs, can lead to failure of the system. In such an application, extracting the temperatures using sensors from locations such as dies and capacitors require expensive modifications and poses technical challenges. It is therefore necessary to create a thermal model for the inverter system to estimate the temperature at various components in order to ensure operation within temperature limits. The model approach is also suitable for predicting the effect on the component temperature and reliability of boundary conditions such as coolant, ambient temperature, and mission profile. This study assesses the reliability of a 250 kW liquid cooled inverter system designed for traction application. The critical failure areas are the DC-link capacitors, and the SiC MOSFET dies, which are rated at 175 °C. The system is modeled as a compact system by reasonably considering each component as a lumped capacitance and estimating the thermal resistance using physical dimensions. Results from the model are then compared against experimental data from constant power testing, and good agreement is observed for the cold plate and gate driver temperatures. With the model fidelity established, the model is then used to implement drive cycles from the Environmental Protection Agency for nonroad applications. The resulting temperature profile for each component is a series of temperature peaks and troughs that contribute to damage and failure. Rainflow counting algorithm is then used to quantify the damage per mini-cycles and used to estimate the predicted life for each component based on their manufacturer provided reliability qualification, and the mission profile is executed on the test bench for validation. The results are then used to generate a system risk matrix that relates the failure risk associated with a certain mission profile and the cooling scheme. It therefore demonstrates that an automotive inverter with SiC switching devices can be credibly assessed for failure risk using a compact model that is independent of boundary conditions, in combination with established reliability correlations and techniques.

scholarly journals How to measure the economic health cost of wildfires – A systematic review of the literature for northern America

2020 ◽  
Vol 29 (11) ◽  
pp. 961
Author(s):  
Ruth Dittrich ◽  
Stuart McCallum
Keyword(s):  
Environmental Protection Agency ◽  
Economic Cost ◽  
Smoke Exposure ◽  
Health Cost ◽  
Mortality And Morbidity ◽  
Wildfire Smoke ◽  
The North ◽  
The Us ◽  
Emergent Literature ◽  
Economic Health

There has been an increasing interest in the economic health cost from smoke exposure from wildfires in the past 20 years, particularly in the north-western USA that is reflected in an emergent literature. In this review, we provide an overview and discussion of studies since 2006 on the health impacts of wildfire smoke and of approaches for the estimation of the associated economic cost. We focus on the choice of key variables such as cost estimators for determining the economic impact of mortality and morbidity effects. In addition, we provide an in-depth discussion and guidance on the functioning, advantages and challenges of BenMAP-CE, freely available software of the US Environmental Protection Agency (EPA) that has been used in a growing number of studies to assess cost from wildfire smoke. We highlight what generates differences in outcomes between relevant studies and make suggestions for increasing the comparability between studies. All studies, however, demonstrate highly significant health cost from smoke exposure, in the millions or billions of US dollars, often driven by increases in mortality. The results indicate the need to take health cost into account for a comprehensive analysis of wildfire impacts.

Degradation Assessment of Gas Turbine Hot Gas Path Components

2016 ◽  
Vol 1133 ◽  
pp. 376-380
Author(s):  
Ahmad Afiq Pauzi
Keyword(s):  
Gas Turbine ◽  
Fuel Mixture ◽  
Operating Conditions ◽  
Research Project ◽  
Damage Mechanisms ◽  
Damage And Failure ◽  
Hot Gas ◽  
Failure Risk ◽  
Path Component ◽  
Damage Processes

Hot gas path component consists of components designed to burn air-fuel mixture in combustion section and provide hot gasses to the turbine section where mechanical power is produced. The aim of this research project is expected to improve the current practices of managing degradation of hot gas path components. Understanding the damage mechanisms is of great interest in reducing the damage and failure risk. In this research, a study was conducted on F-Class type gas turbine hot gas path components assembly. It involved extensive examination and testing of the components which had been in operations for 24,000 hours since the last shutdown. Various factors such as installation, operating conditions, hardness and material of constructions were also investigated. This paper reports the initial findings of the study of hot gas path components degradation. It describes the damage observed on the affected areas of the components and proposes the factors that contribute to the damage processes. Potential solutions for mitigating the damages are also discussed.

scholarly journals Investigation of effects of varying model inputs on mercury deposition estimates in the Southwest US

2012 ◽  
Vol 12 (4) ◽  
pp. 10273-10304
Author(s):  
T. Myers ◽  
R. D. Atkinson ◽  
O. R. Bullock ◽  
J. O. Bash
Keyword(s):  
Boundary Conditions ◽  
Environmental Protection Agency ◽  
Dry Deposition ◽  
Land Surface ◽  
Atmospheric Mercury ◽  
Mercury Species ◽  
Mercury Deposition ◽  
Global Models ◽  
Wet And Dry Deposition ◽  
Meteorological Input

Abstract. The Community Multiscale Air Quality (CMAQ) model version 4.7.1 was used to simulate mercury wet and dry deposition for a domain covering the contiguous United States (US). The simulations used MM5-derived meteorological input fields and the US Environmental Protection Agency (EPA) Clear Air Mercury Rule (CAMR) emissions inventory. Using sensitivity simulations with different boundary conditions and tracer simulations, this investigation focuses on the contributions of boundary concentrations to deposited mercury in the Southwest (SW) US. Concentrations of oxidized mercury species along the boundaries of the domain, in particular the upper layers of the domain, can make significant contributions to the simulated wet and dry deposition of mercury in the SW US. In order to better understand the contributions of boundary conditions to deposition, inert tracer simulations were conducted to quantify the relative amount of an atmospheric constituent transported across the boundaries of the domain at various altitudes and to quantify the amount that reaches and potentially deposits to the land surface in the SW US. Simulations using alternate sets of boundary concentrations, including estimates from global models (Goddard Earth Observing System-Chem (GEOS-Chem) and the Global/Regional Atmospheric Heavy Metals (GRAHM) model), and alternate meteorological input fields (for different years) are analyzed in this paper. CMAQ dry deposition in the SW US is sensitive to differences in the atmospheric dynamics and atmospheric mercury chemistry parameterizations between the global models used for boundary conditions.

scholarly journals Conformal boundary conditions from cutoff AdS3

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Evan Coleman ◽  
Vasudev Shyam
Keyword(s):  
Boundary Conditions ◽  
Ground State ◽  
State Energy ◽  
Growth Characteristic ◽  
Temperature Limit ◽  
Flow Equation ◽  
Legendre Transform ◽  
Conformal Boundary ◽  
Deformation Parameters ◽  
Metric Fluctuations

Abstract We construct a particular flow in the space of 2D Euclidean QFTs on a torus, which we argue is dual to a class of solutions in 3D Euclidean gravity with conformal boundary conditions. This new flow comes from a Legendre transform of the kernel which implements the T$$ \overline{T} $$ T ¯ deformation, and is motivated by the need for boundary conditions in Euclidean gravity to be elliptic, i.e. that they have well-defined propagators for metric fluctuations. We demonstrate equivalence between our flow equation and variants of the Wheeler de-Witt equation for a torus universe in the so-called Constant Mean Curvature (CMC) slicing. We derive a kernel for the flow, and we compute the corresponding ground state energy in the low-temperature limit. Once deformation parameters are fixed, the existence of the ground state is independent of the initial data, provided the seed theory is a CFT. The high-temperature density of states has Cardy-like behavior, rather than the Hagedorn growth characteristic of T$$ \overline{T} $$ T ¯ -deformed theories.

scholarly journals A Multiscale Approach to Polycrystalline Materials Damage and Failure

2014 ◽  
Vol 627 ◽  
pp. 33-36 ◽  
Author(s):  
Ivano Benedetti ◽  
M.H. Aliabadi
Keyword(s):  
Three Dimensional ◽  
Polycrystalline Materials ◽  
Multiscale Approach ◽  
Damage Localization ◽  
Dimensional Approach ◽  
Material Degradation ◽  
Component Level ◽  
Damage And Failure ◽  
Local Material ◽  
Macro Scale

A two-scale three-dimensional approach for degradation and failure in polycrystalline materials is presented. The method involves the component level and the grain scale. The damage-induced softening at the macroscale is modelled employing an initial stress boundary element approach. The microscopic degradation is explicitly modelled associating Representative Volume Elements (RVEs) to relevant points of the macro continuum and employing a cohesive-frictional 3D grain-boundary formulation to simulate intergranular degradation and failure in the Voronoi morphology. Macro-strains are downscaled as RVEs' periodic boundary conditions, while overall macro-stresses are obtained upscaling the micro-stress field via volume averages. The comparison between effective macro-stresses for the damaged and undamaged RVEs allows to define a macroscopic measure of local material degradation. Some attention is devoted to avoiding pathological damage localization at the macro-scale. The multiscale processing algorithm is described and some preliminary results are illustrated.

scholarly journals Investigation of effects of varying model inputs on mercury deposition estimates in the Southwest US

2013 ◽  
Vol 13 (2) ◽  
pp. 997-1009 ◽  
Author(s):  
T. Myers ◽  
R. D. Atkinson ◽  
O. R. Bullock ◽  
J. O. Bash
Keyword(s):  
Boundary Conditions ◽  
Environmental Protection Agency ◽  
Dry Deposition ◽  
Land Surface ◽  
Atmospheric Mercury ◽  
Mercury Species ◽  
Mercury Deposition ◽  
Global Models ◽  
Wet And Dry Deposition ◽  
Meteorological Input

Abstract. The Community Multiscale Air Quality (CMAQ) model version 4.7.1 was used to simulate mercury wet and dry deposition for a domain covering the continental United States (US). The simulations used MM5-derived meteorological input fields and the US Environmental Protection Agency (EPA) Clear Air Mercury Rule (CAMR) emissions inventory. Using sensitivity simulations with different boundary conditions and tracer simulations, this investigation focuses on the contributions of boundary concentrations to deposited mercury in the Southwest (SW) US. Concentrations of oxidized mercury species along the boundaries of the domain, in particular the upper layers of the domain, can make significant contributions to the simulated wet and dry deposition of mercury in the SW US. In order to better understand the contributions of boundary conditions to deposition, inert tracer simulations were conducted to quantify the relative amount of an atmospheric constituent transported across the boundaries of the domain at various altitudes and to quantify the amount that reaches and potentially deposits to the land surface in the SW US. Simulations using alternate sets of boundary concentrations, including estimates from global models (Goddard Earth Observing System-Chem (GEOS-Chem) and the Global/Regional Atmospheric Heavy Metals (GRAHM) model), and alternate meteorological input fields (for different years) are analyzed in this paper. CMAQ dry deposition in the SW US is sensitive to differences in the atmospheric dynamics and atmospheric mercury chemistry parameterizations between the global models used for boundary conditions.

scholarly journals The Dynamic Response and Failure Model of Thin Plate Rock Mass under Impact Load

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Feng Li ◽  
Xinhui Dong ◽  
Yue Wang ◽  
Hanwu Liu ◽  
Chuang Chen ◽  
...  
Keyword(s):  
Rock Mass ◽  
Dynamic Response ◽  
Boundary Conditions ◽  
Failure Mechanism ◽  
Thin Plate ◽  
Impact Load ◽  
Vibration Modes ◽  
Plate Model ◽  
Damage And Failure ◽  
Dynamic Disaster

The layered rock mass widely exists in mining, construction, transportation, and water conservancy projects, and the damage phenomena of plate crack and spalling often occurs in the process of coal and rock dynamic disaster in deep mining. Therefore, the rock mass nearby excavation surface is usually considered to be composed of layers of thin plate rock mass to reveal the damage and failure mechanism of rock mass. In the whole dynamic process of mining and coal and rock dynamic disaster, rock mass would bear the dynamic disturbance from mine earthquake, and at present, the mechanical characteristics of rock mass are mainly studied under static load, while dynamic mechanical response characteristics and the mechanisms of dynamic damage, failure, and disaster-causing are still unclear. This study mainly focused on the dynamic response characteristic and failure mechanism of rock mass based on a rectangular thin plate model. The frequency equations and deflection equations of the thin plate rock mass with different boundary conditions (S-F-S-F, S-C-S-C, and C-C-C-C) were established under free vibration by the thin plate model and the dual equation of the Hamilton system, and the deflection equations under impact load were derived based on the Duhamel integral. And then, the effective vibration modes of the thin plate rock mass with different boundary conditions and their natural frequencies were obtained by Newton’s iterative method. Based on the third-strength theory and the numerical simulation results by LS-DYNA, the maximum shear of the effective vibration modes and the processes of damage and failure under impact load were analyzed. The research results showed that the initial position of damage and failure may be determined by effective vibration mode with the lowest frequency; the develop tendency of which by the combined actions of other effective vibration modes and the effective vibration modes with lower frequency could have greater influence on the process of damage and failure of the thin plate rock mass, which are beneficial to revealing the mechanism of coal and rock dynamic disaster.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

Representation of information in SEM by equal signal lines

1978 ◽  
Vol 36 (1) ◽  
pp. 144-145
Author(s):  
E. Rau ◽  
N. Karelin ◽  
V. Dukov ◽  
M. Kolomeytsev ◽  
S. Gavrikov ◽  
...  
Keyword(s):  
Electronic System ◽  
Space Distribution ◽  
Specimen Surface ◽  
Universal Method ◽  
Base Level ◽  
Signal Value ◽  
Information Signal ◽  
Fixed Base ◽  
Scanning Line ◽  
Amplitude Analyzer

There are different methods and devices for the increase of the videosignal information in SEM. For example, with the help of special pure electronic [1] and opto-electronic [2] systems equipotential areas on the specimen surface in SEM were obtained. This report generalizes quantitative universal method for space distribution representation of research specimen parameter by contour equal signal lines. The method is based on principle of comparison of information signal value with the fixed levels.Transformation image system for obtaining equal signal lines maps was developed in two versions:1)In pure electronic system [3] it is necessary to compare signal U (see Fig.1-a), which gives potential distribution on specimen surface along each scanning line with fixed base level signals εifor obtaining quantitative equipotential information on solid state surface. The amplitude analyzer-comparator gives flare sport videopulses at any fixed coordinate and any instant time when initial signal U is equal to one of the base level signals ε.

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