scholarly journals High-Frequency Non-Invasive Magnetic Field-Based Condition Monitoring of SiC Power MOSFET Modules

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6720
Author(s):  
Javad Naghibi ◽  
Kamyar Mehran ◽  
Martin P. Foster
Keyword(s):  
Magnetic Field ◽  
Condition Monitoring ◽  
Switching Frequency ◽  
Power Module ◽  
Power Mosfet ◽  
Wire Bond ◽  
Wide Range ◽  
The Wire ◽  
Lift Off ◽  
Set Up

Current distribution anomaly can be used to indicate the onset of package-related failures modes in Silicon Carbide power MOSFET modules. In this paper, we propose to obtain the wire bond’s magnetic field profile using an array of Tunnel Magneto-Resistance (TMR) sensors, and characterise the small changes in the current density distribution to find the onset of the wire bond degradation processes, including wire bond lift-off, wire bond cracking, and wire bond fracture. We propose a novel condition monitoring technique where a non-galvanic high-bandwidth sensing and a reliability model monitor the health of the power switches. We designed a dedicated calibration set-up to examine the sensor array and calibrated to demonstrate the adequate sensitivity to a minimum 5% current anomaly detection in a single wire bond of the switching devices operating with 50 kHz switching frequency. We use a hardware-in-the-loop (HIL) experimental set-up to replicate wire bond-related failures in a 1200V/55A SiC MOSFET power module of a DC/DC Boost converter. Signal conditioning circuits are further designed to amplify and buffer the sensor readings. Experimental results showed the proposed technique is able to detect a wide range of package-related failures.

CALCULATION OF FREQUENCIES AND RELATIVE INTENSITIES OF NUCLEAR SPIN RESONANCE LINES IN CRYSTALS

1958 ◽  
Vol 36 (10) ◽  
pp. 1286-1294 ◽  
Author(s):  
M. Bloom ◽  
L. B. Robinson ◽  
G. M. Volkoff
Keyword(s):  
Magnetic Field ◽  
Nuclear Spin ◽  
Energy Levels ◽  
Magnetization Vector ◽  
Single Coil ◽  
Wide Range ◽  
Spin Resonance ◽  
Oscillating Magnetic Field ◽  
The Difference ◽  
Set Up

Previous calculations of the dependence on the strength of the external magnetic field H0 of the energy levels and the expected frequencies of nuclear spin resonance lines of Al27 nuclei in a single crystal of LiAl(SiO3)2 (spodumene) have been extended over a wide range of H0 to more general orientations of the crystal with respect to H0.In order to describe the variation with H0 of the relative signal strength of a nuclear spin resonance line in a crystal, as observed with a crossed-coil spectrometer, a system of modified Bloch equations has been set up which describe the behavior of the magnetization vector of a two-level system when transitions are induced by an oscillating magnetic field. Solutions of these equations are used to explain the difference in the dependence on H0 of signal strengths in crossed-coil and in single-coil spectrometers.

scholarly journals Thermal and Electrical Characterization of Power Mosfet Module Using Coupled Field Analysis

2019 ◽  
Vol 35 (5) ◽  
pp. 641-655 ◽  
Author(s):  
H.-C. Cheng ◽  
C.-H. Wu ◽  
S.-Y. Lin
Keyword(s):  
Circuit Simulation ◽  
Field Analysis ◽  
Electrical Performance ◽  
Switching Frequency ◽  
Power Losses ◽  
Ambient Conditions ◽  
Power Module ◽  
Power Mosfet ◽  
Operation Conditions ◽  
Coupled Field

ABSTRACTTemperature resulting from the joule heating power and the turn-on and turn-off dissipation of high-power, high-frequency applications is the root cause of their thermal instability, electrical performance degradation, and even thermal-fatigue failure. Thus, the study presents thermal and electrical characterizations of the power MOSFET module packaged in SOT-227 under natural convection and forced convection through three-dimensional (3D) thermal-electric (TE) coupled field analysis. In addition, the influences of some key parameters like electric loads, ambient conditions, thermal management considerations (heat sink, heat spreader) and operation conditions (duty cycle and switching frequency) on the power loss and thermal performance of the power module are addressed. The study starts from a suitable estimation of the power losses, where the conduction losses are calculated using the temperature- and gate-voltage-dependent on-state resistance and drain current through the device, and the switching losses are predicted based on the ideal switching waveforms of the power MOSFETs applied. The effectiveness of the theoretical predictions in terms of device’s power losses and temperatures is demonstrated through comparison with the results of circuit simulation and thermal experiment.

Application of Kriging and Radial Basis Function for Reliability Optimization in Power Modules

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Pushparajah Rajaguru ◽  
Stoyan Stoyanov ◽  
Hua Lu ◽  
Chris Bailey
Keyword(s):  
Reduced Order Modeling ◽  
Module Structure ◽  
Power Electronic ◽  
Aluminum Wire ◽  
Power Module ◽  
Reduced Order ◽  
Wire Bond ◽  
Radial Basis ◽  
The Wire ◽  
Point Estimation Method

This paper discusses the design for reliability of a wire bond structure in a power electronic module based on computational approach that integrates methods for high fidelity analysis, reduced order modeling, numerical risk analysis, and optimization. This methodology is demonstrated on a wire bond structure in a power electronic module with the aim of reducing the chance of failure due to the wire bond lift off in a power electronic module. In particular, wire bond reliability of the power module related to the thermal fatigue material degradation of aluminum wire is one of the main concerns. Understanding the performance, reliability, and robustness of wire bond is a key factor for the future development and success of the power electronic module technology. The main focus in this study is on the application of reduced order modeling techniques and the development of the associated models for fast design evaluation and analysis. The discussion is on methods for approximate response surface modeling based on interpolation techniques using Kriging and radial basis functions. The reduced order modeling approach uses prediction data for the electrothermomechanical behavior of the power module wire bond design obtained through nonlinear transient finite element simulations, in particular, for the fatigue lifetime of the aluminum wire attached to the silicon chip and the warpage (displacement) of the wire in the module. These reduced order models are used for the analysis of the effect of design uncertainties on the reliability of these advanced electronics modules. To assess the effect of uncertain design data, different methods for estimating the variation of reliability-related metrics of the wire bond model are researched and tested. Sample-based methods, such as full-scale Monte Carlo and Latin hypercube, and analytical approximate methods, such as first order second moment (FOSM) and point estimation method (PEM), are investigated, and their accuracy is compared. The optimization modeling analyzes the probabilistic nature of the reliability problem of the aluminum wire bond structures under investigation. Optimization tasks with design uncertainty are identified and solved using a particle swarm optimization algorithm. The probabilistic optimization deals with two different characteristic performance metrics of the design, the electrothermomechanical fatigue reliability of the aluminum wire attached to the chip and the thermally induced warpage of the wire in the module structure. The objective in this analysis is to ensure that the design has the required reliability and meets a number of additional requirements.

Settlers or Movers? The Temporality of Past Migrations, Political Inaction and its Consequences, 1945–1985

2018 ◽  
Author(s):  
Jozefien De Bock
Keyword(s):  
Temporary Workers ◽  
Guest Workers ◽  
Temporary Migration ◽  
Wide Range ◽  
Settler Societies ◽  
Future Policy ◽  
Set Up ◽  
Legal Frameworks ◽  
Temporary Migrants ◽  
Multicultural Policies

Historically, those societies that have the longest tradition in multicultural policies are settler societies. The question of how to deal with temporary migrants has only recently aroused their interest. In Europe, temporary migration programmes have a much longer history. In the period after WWII, a wide range of legal frameworks were set up to import temporary workers, who came to be known as guest workers. In the end, many of these ‘guests’ settled in Europe permanently. Their presence lay at the basis of European multicultural policies. However, when these policies were drafted, the former mobility of guest workers had been forgotten. This chapter will focus on this mobility of initially temporary workers, comparing the period of economic growth 1945-1974 with the years after the 1974 economic crisis. Further, it will look at the kind of policies that were developed towards guest workers in the era before multiculturalism. This way, it shows how their consideration as temporary residents had far-reaching consequences for the immigrants, their descendants and the receiving societies involved. The chapter will finish by suggesting a number of lessons from the past. If the mobility-gap between guest workers and present-day migrants is not as big as generally assumed, then the consequences of previous neglect should serve as a warning for future policy making.

ORAL HISTORY SOURCES AS LEARNING MATERIALS: A CASE STUDY OF THE NATIONAL UNIVERSITY OF SCIENCE AND TECHNOLOGY

2016 ◽  
Vol 3 (2) ◽  
pp. 82-93
Author(s):  
Gugulethu Shamaine Nkala ◽  
Rodreck David
Keyword(s):  
Oral History ◽  
Learning Experience ◽  
Science And Technology ◽  
Group Discussion ◽  
Human Interaction ◽  
Learning Material ◽  
Wide Range ◽  
National Archives ◽  
National University ◽  
Set Up

Knowledge presented by Oral History (OH) is unique in that it shares the tacit perspective, thoughts, opinions and understanding of the interviewee in its primary form. While teachers, lecturers and other education specialists have at their disposal a wide range of primary, secondary and tertiary sources upon which to relate and share or impart knowledge, OH presents a rich source of information that can improve the learning and knowledge impartation experience. The uniqueness of OH is presented in the following advantages of its use: it allows one to learn about the perspectives of individuals who might not otherwise appear in the historical record; it allows one to compensate for the digital age; one can learn different kinds of information; it provides historical actors with an opportunity to tell their own stories in their own words; and it offers a rich opportunity for human interaction. This article discusses the placement of oral history in the classroom set-up by investigating its use as a source of learning material presented by the National Archives of Zimbabwe to students in the Department of Records and Archives Management at the National University of Science and Technology (NUST). Interviews and a group discussion were used to gather data from an archivist at the National Archives of Zimbabwe, lecturers and students in the Department of Records and Archives Management at NUST, respectively. These groups were approached on the usability, uniqueness and other characteristics that support this type of knowledge about OH in a tertiary learning experience. The findings indicate several qualities that reflect the richness of OH as a teaching source material in a classroom set-up. It further points to weak areas that may be addressed where the source is considered a viable strategy for knowledge sharing and learning. The researchers present a possible model that can be used to champion the use of this rich knowledge source in classroom education at this university and in similar set-ups. 

Monte Carlo calculation of the energy parameters and spatial distribution of the cathodic arc ions while passing through the macro-particles filters

2018 ◽  
Vol 1 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Alexey Chernogor ◽  
Igor Blinkov ◽  
Alexey Volkhonskiy
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Monte Carlo ◽  
Monte Carlo Calculation ◽  
Inhomogeneous Magnetic Field ◽  
Flow Energy ◽  
Wide Range ◽  
Field Concentrator ◽  
Cathodic Arc ◽  
The Magnetic Field

The flow, energy distribution and concentrations profiles of Ti ions in cathodic arc are studied by test particle Monte Carlo simulations with considering the mass transfer through the macro-particles filters with inhomogeneous magnetic field. The loss of ions due to their deposition on filter walls was calculated as a function of electric current and number of turns in the coil. The magnetic field concentrator that arises in the bending region of the filters leads to increase the loss of the ions component of cathodic arc. The ions loss up to 80 % of their energy resulted by the paired elastic collisions which correspond to the experimental results. The ion fluxes arriving at the surface of the substrates during planetary rotating of them opposite the evaporators mounted to each other at an angle of 120° characterized by the wide range of mutual overlapping.

Nanofiltration of endocrine disrupting compounds

2003 ◽  
Vol 3 (5-6) ◽  
pp. 321-327 ◽  
Author(s):  
M. Gallenkemper ◽  
T. Wintgens ◽  
T. Melin
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Endocrine Disrupting Compounds ◽  
Municipal Wastewater Treatment ◽  
Water And Wastewater Treatment ◽  
Wide Range ◽  
Endocrine Disrupting ◽  
Municipal Wastewater Treatment Plants ◽  
Set Up

Endocrine disrupting compounds can affect the hormone system in organisms. A wide range of endocrine disrupters were found in sewage and effluents of municipal wastewater treatment plants. Toxicological evaluations indicate that conventional wastewater treatment plants are not able to remove these substances sufficiently before disposing effluent into the environment. Membrane technology, which is proving to be an effective barrier to these substances, is the subject of this research. Nanofiltration provides high quality permeates in water and wastewater treatment. Eleven different nanofiltration membranes were tested in the laboratory set-up. The observed retention for nonylphenol (NP) and bisphenol A (BPA) ranged between 70% and 100%. The contact angle is an indicator for the hydrophobicity of a membrane, whose influence on the permeability and retention of NP was evident. The retention of BPA was found to be inversely proportional to the membrane permeability.

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

scholarly journals A System-Agnostic, Adaptable and Extensible Animal Support Cradle System for Cardio-Respiratory-Synchronised, and Other, Multi-Modal Imaging of Small Animals

Tomography ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 39-54
Author(s):  
Veerle Kersemans ◽  
Stuart Gilchrist ◽  
Philip Danny Allen ◽  
Sheena Wallington ◽  
Paul Kinchesh ◽  
...  
Keyword(s):  
Scientific Data ◽  
Cardiac Monitoring ◽  
Small Animals ◽  
Maintenance System ◽  
Wide Range ◽  
Set Up ◽  
Animal Handling ◽  
Imaging Performance ◽  
Significant Effort

Standardisation of animal handling procedures for a wide range of preclinical imaging scanners will improve imaging performance and reproducibility of scientific data. Whilst there has been significant effort in defining how well scanners should operate and how in vivo experimentation should be practised, there is little detail on how to achieve optimal scanner performance with best practices in animal welfare. Here, we describe a system-agnostic, adaptable and extensible animal support cradle system for cardio-respiratory-synchronised, and other, multi-modal imaging of small animals. The animal support cradle can be adapted on a per application basis and features integrated tubing for anaesthetic and tracer delivery, an electrically driven rectal temperature maintenance system and respiratory and cardiac monitoring. Through a combination of careful material and device selection, we have described an approach that allows animals to be transferred whilst under general anaesthesia between any of the tomographic scanners we currently or have previously operated. The set-up is minimally invasive, cheap and easy to implement and for multi-modal, multi-vendor imaging of small animals.

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