535 research outputs found
Temperature Monitoring of Multi-Chip SiC MOSFET Modules: On-Chip RTDs vs. VSD(T)
No full textIn this paper we compare on-chip RTD sensors and the V SD (T) method for temperature measurement of multi-chip SiC MOSFET modules. We find that the average temperature across multiple chips measured via on-chip RTDs correlates closely with the V SD (T). However, the minimum and maximum chip temperature changes according to the module’s operating conditions. This cannot be detected by the V SD (T) method. In a half-bridge module with 4-chips per switch position, we apply two operating conditions that give the same measured temperature via V SD (T). The maximum chip temperature, measured via the on-chip RTD, deviates over 5°C. This may have implications for power cycling lifetime on multi-chip power modules. We also demonstrate the use of the on-chip RTDs in an IGBT inverter
Thermal Characteristics of Liquid Metal Interconnects for Power Semiconductors
Get PDFDue to its electrical conductivity and fluidity, liquid metal interconnection has the potential to become a new industrial power semiconductors packaging application method to solve the failure of wire bonding liftoff and improve the reliability of power semiconductor applications. As a crucial characteristic in use, the thermal characteristics of liquid metal interconnects for power semiconductors are obtained experimentally in this paper. By powering a diode die in a bridge busbar liquid metal interconnect structure, the thermal resistance from the die to the ambient is extracted. The result shows that the liquid metal interconnects method has the potential to improve the thermal behavior of power semiconductors compared with wire-bonding interconnection. The finite element simulation explains the possible reasons causing abnormal temperature responses among some samples. Besides, during the test, a slow decline in the forward voltage of the module is observed.</p
An empirical, model, or virtual author?
Get PDFThe article titled Autor: empiryczny, modelowy czy wirtualny? [“An empirical, model, or virtual
author?”] presents a discussion about the terms used in the title which was held by the article’s
authors. P. Bohuszewicz defends the validity of the concepts of an empirical and a virtual author,
the latter being the result of “rewriting” Umberto Eco’s idea of a model author. T. Szymon Markiewka
claims that the concept of a model author and that of a virtual author are unnecessary
multiplications of theoretical entities: we only need the concept of an empirical author, but we
also need to remember about all the complications related to this concept.2219120511Przestrzenie Teori
Szymon Rundstein’s Theory of a Legal Norm — Preliminary Assumptions
No full textThe subject of this article is an analysis of Szymon Rundstein’s theory of a legal
norm. In the first part of his study, the author discusses primary trends in the theory of law in
inter-war Poland. Indicating that normative concepts had few supporters, the author simultaneously
notes that they attracted law practitioners dealing with legal theory. The second part is an
attempt at reconstructing Szymon Rundstein’s views on legal theory. Having proposed his methodology,
the author analyzes Szymon Rundstein’s statements regarding both a legal norm, a central
category in his considerations, and a normative system. In conclusion, it has been pointed
out that although Szymon Rundstein takes a very rigorous approach to the normative assumption
about the “purity” of the theory of law, he appears to be fascinated with phenomenology
and frequently alludes to psychological theories. Specifically, many references alluding to Leon
Petrażycki’s tradition can be traced in his writings. Thus, Szymon Rundstein’s theory of a legal
norm modifies the normative assumptions of Hans Kelsen and is an original concept that was
developed under the influence of many theoretical-legal views. It undoubtedly has a lot to offer
and requires „re-reading”
Design of metal substrate PFC motor drive "An investigation of thermal performance of IMS with WBG devices"
No full textAdvanced dimming strategy for solid state luminaires
No full textIncreased luminaire gamut as well as increase in luminous efficiency is found when the LED based luminaire is driven by a hybrid PWM/AM dimming technique. This technique is applicable to any n-chromaticity luminaire but it is especially suitable for trichromatic RGB luminaires that do not have inherent degrees of freedom. Diodes' properties under the hybrid dimming method were measured and used in nonlinear optimization routine to find the driving conditions that yield e.g. the highest possible efficacy for a given color point. <br/
IMPROVING LED EFFICIENCY THROUGH THERMOELECTRIC COOLERS: led efficiency
No full textRecent developments in power Light Emitting Diode(LED) industry made LEDs suitable for being effi-ciently used in high intensity lighting fixtures. The ap-plied power can reach up to 60 W/mm2 in the highoutput LEDs, while 80% of this power dissipated asheat loss. The heat loss increases the LED temper-ature, so that its efficiency and lifetime reduce. Aneffective cooling can provide suitable temperature dis-tribution on the LED. Each LED needs specific designand cooling properties of the heat sink system. An in-teresting cooling technology that can be integrated withthe LEDs is thermoelectric cooler (TEC). Thermoelec-tric cooler is able to move the hot zone, due to the heatloss, in the LEDs to the heat sink. Therefore, the con-version efficiency of LEDs enhances at lower operationtemperatureRecent developments in power Light Emitting Diode(LED) industry made LEDs suitable for being effi-ciently used in high intensity lighting fixtures. The ap-plied power can reach up to 60 W/mm2 in the highoutput LEDs, while 80% of this power dissipated asheat loss. The heat loss increases the LED temper-ature, so that its efficiency and lifetime reduce. Aneffective cooling can provide suitable temperature dis-tribution on the LED. Each LED needs specific designand cooling properties of the heat sink system. An in-teresting cooling technology that can be integrated withthe LEDs is thermoelectric cooler (TEC). Thermoelec-tric cooler is able to move the hot zone, due to the heatloss, in the LEDs to the heat sink. Therefore, the con-version efficiency of LEDs enhances at lower operationtemperatur
Using a Variable Capacitor as a Voltage Actuator
No full textGate drivers are a ubiquitous component in power electronics, and is therefore subject to much research. An fairly unexplored topic is using a variable capacitor as a gate driver. This project analyses and designs a variable capacitor for use as a gate driver. The idea is successfully tested using a basic plate capacitor, which is used to turn on a GaNFET by rapidly removing the dielectric material. This experiment, along with simulation studies give insight into a possible design. Using these insights, a variable capacitor is designed. The capacitor consists of two PCBs, with one being spun around an axis by a motor. This spinning causes the capacitance to change. The capacitance is measured using a voltage divider, and it is found to deviate slightly from expectations. The variable capacitor is inserted into an electrical circuit and it is found that a variable voltage can be achieved over a load similar to the gate of a FET. The predicted voltages do not correspond with many of the measured voltages. When the load is exchanged for a GaNFET, the variable capacitor can successfully regulate turn on and turn off. Instability is seen in the gate and drain voltages of the GaNFET. It is concluded that the variable capacitor can be used to regulate a voltage, but it is not suitable for use as a gate driver. To finish, some ideas are given for future work with this idea.Gate drivers are a ubiquitous component in power electronics, and is therefore subject to much research. An fairly unexplored topic is using a variable capacitor as a gate driver. This project analyses and designs a variable capacitor for use as a gate driver. The idea is successfully tested using a basic plate capacitor, which is used to turn on a GaNFET by rapidly removing the dielectric material. This experiment, along with simulation studies give insight into a possible design. Using these insights, a variable capacitor is designed. The capacitor consists of two PCBs, with one being spun around an axis by a motor. This spinning causes the capacitance to change. The capacitance is measured using a voltage divider, and it is found to deviate slightly from expectations. The variable capacitor is inserted into an electrical circuit and it is found that a variable voltage can be achieved over a load similar to the gate of a FET. The predicted voltages do not correspond with many of the measured voltages. When the load is exchanged for a GaNFET, the variable capacitor can successfully regulate turn on and turn off. Instability is seen in the gate and drain voltages of the GaNFET. It is concluded that the variable capacitor can be used to regulate a voltage, but it is not suitable for use as a gate driver. To finish, some ideas are given for future work with this idea
Proof-of-Concept for an On-Chip Kelvin-Emitter RTD Sensor for Junction Temperature Monitoring of IGBTs
No full textThis paper presents the use of an on-chip Kelvin-Emitter Resistor to monitor the junction temperature of an IGBT during converter operation. The Kelvin-Emitter Resistor is manufactured using a 250&#x03BC;m Aluminium Nitride substrate with a Platinum resistive trace. The resistor is mounted directly on the Emitter surface metallization using conductive epoxy and is evaluated by injecting a small sensing current between the Power-Emitter and Kelvin-Emitter terminals during the on-state of a 600V/75A IGBT. The IGBT is operated in a single-phase inverter and the measured temperature is compared to measurements made using an optical fibre, an Infra-Red Camera, and the VCE(T) method.</p
Optimization of hydraulic shapes with application of CFD, genetic algorithm and meta-modelling
No full textThe aim of the project is to evaluate the performance of the genetic algorithm and a specific type of metamodeling (called kriging) in an engineering optimization. An automated environment for the CFD analysis is built and connected with several types of optimization strategies. The key is to find an optimal genetic algorithm’s setup, which means a good trade-off between acquired results and the optimization time. Finally, the performance of several optimization techniques is compared
- …
