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Der Anspruch an Energieversorger wird wachsen: in Zukunft gewinnen vor allem Aufgaben wie die Entwicklung digitalisierter Produkte/Dienstleistungen sowie ökologische Aktivitäten an Relevanz. Dies zeigt die Hochschule Reutlingen in ihrer aktuellen Untersuchung unter Aufsichtsräten, Geschäftsführern und Führungskräften. Trotz der erwarteten Veränderungen: die Aufsichtsräte sind sich zwar ihrem Druck zu mehr Professionalisierung bewusst, scheinen aktuell aber nur mäßig für die künftigen Herausforderungen des Unternehmens gerüstet. Besonders relevant dabei: die Professionalisierung der Gremienarbeit in kommunalen EVU ermöglicht einen höheren wahrgenommenen Unternehmenserfolg. So die Studie des Reutlinger Energiezentrums and der Hochschule Reutlingen im Auftrag von fünf Unternehmen der Branche.
DC-DC-converters are used in many different applications. Specifying the switching frequency is the most important parameter to calculate component costs and required space. Especially automotive applications of small brushed- or brushless dc-motors and the increasing number of DC-DC-converters have high requirements on the structual space (low box volume). This is of particular importance for automotive converters for the new 48 V board net. Multiplying the frequency by two will reduce the size of the power inductor by half at a given specification for output-voltage ripple. Smaller power inductors result in reduced losses due to smaller series resistance and parasitic capacitance. Furthermore a larger switching frequency decreases the size of the DC link capacitors. The circuit will get more idealized. However, as the switching losses increase with frequency, a DC-DC-converter can only benefit from these advantages if the switching behavior can be improved.
This paper presents an optimization method to increase switching slope and switching frequency of a 3.6 kW 3-phase step-up converter by separating the design and layout process into two parts. The first part is the power stage which carries the load current. It contains the power inductance and the drain-source-channel of the power MOSFETs. The second part is the driver circuit which contains the driver ICs, the gate resistor and the gate input impedance. While the switching slope was measured to be improved by 50 % , the switching time decreased by 20 %. Hence, the switching frequency of the step-up converter could be increased from 100 kHz to 200 kHz without loss increase. By mounting the driver ICs in a piggyback configuration in close proximity to the power stage, the parasitics could be further reduced significantly and 500 kHz switching frequency could be achieved with 97.5 % efficiency.
A novel gate driving approach to balance the transient current of parallel-connected GaN-HEMTs
(2018)
To enable higher current handling capability of GaN-based DC/DC converters, devices have to be used in parallel. However, their switching times differ, especially if their threshold voltages are not identical, which causes unbalanced device current. This paper focuses on the homogeneous distribution of turn-on switching losses of GaN-HEMTs connected in parallel. By applying a new gate driver concept, the transient current is distributed evenly. The effectiveness of this concept is demonstrated by double pulse measurements, for switching currents up to 45A and a voltage of 400V. A uniform current distribution is achieved, including a reduction of the turn-on losses by 50% compared to a conventional setup.
A procedural approach to automate the manual design process in analog integrated circuit design
(2018)
This paper presents a novel approach to automating the design of analog integrated circuits: (1) the Expert Design Plan (EDP), a procedural generator, and (2) the EDP Language, a high-level description language for writing an EDP. An EDP is a parameterizable, executable script, which reproduces a designer’s course of action when designing a circuit. Thus, an EDP formalizes the design expert’s knowledge-based strategy and makes it reusable. Since it is essential that an EDP represents a circuit designers’ way of thinking and working as close as possible, the designers themselves should be enabled to create the EDP. Therefore, our approach provides a input method through a domain-specific language called EDP Language (EDPL). Using this language is intuitive and requires no special training. In an exemplary implementation of our approach, a common-source amplifier is automatically sized using a set of only 10 instructions. Even in the first usage our EDP approach has appeared to be more efficient than the manual sizing process.
The demonstration project Virtual Power Plant Neckar-Alb is constructing a Virtual Power Plant (VPP) demonstration site at the Reutlingen University campus. The VPP demonstrator integrates a heterogeneous set of distributed energy resources (DERs) which are connected to control the infrastructure and an energy management system. This paper describes the components and the architecture of the demonstrator and presents strategies for demonstration of multiple optimization and control systems with different control paradigms.
This paper addresses the turn-on switching process of insulated-gate bipolar transistor (IGBT) modules with anti-parallel free-wheeling diodes (FWD) used in inductive load switching power applications. An increase in efficiency, i.e. decrease in switching losses, calls for a fast switching process of the IGBT, but this commonly implies high values of the reverse-recovery current overshoot. To overcome this undesired behaviour, a solution was proposed which achieves an independent control of the collector current slope and peak reverse recovery current by applying a gate current that is briefly turned negative during the turn-on process. The feasibility of this approach has already been shown, however, a sophisticated control method is required for applying it in applications with varying currents, temperature and device parameters. In this paper a solution based on an adaptive, iterative closed-loop ontrol is proposed. Its effectiveness is demonstrated by experimental results from a 1200 V/200A IGBT power module for different load currents and reverse-recovery current overshoots.
An experimental study of a zero voltage switching SiC boost converter with an active snubber network
(2015)
This paper presents a quasi-resonant, zero voltage switching (ZVS) SiC boost converter for an output power of up to 10 kW. The converter is realized with an easily controllable active snubber network that allows a reduction of switching losses by minimizing the voltage stress applied to the active switch. With this approach, an increase of the switching frequency is possible, allowing a reduction of the system size. Experiments show a maximum converter efficiency up to 99.2% for a switching frequency of 100 kHz. A second version of the converter enables a further size reduction by increasing the switching frequency to 300 kHz while still reaching a high efficiency up to 98.4 %.
IGBT modules with anti-parallel FWDs are widely used in inductive load switching power applications, such as motor drive applications. Nowadays there is a continuous effort to increase the efficiency of such systems by decreasing their switching losses. This paper addresses the problems arising in the turn-on process of an IGBT working in hard-switching conditions. A method is proposed which achieves – contrary to most other approaches – a high switching speed and, at the same time, a low peak reverse-recovery current. This is done by applying an improved gate current waveform that is briefly lowered during the turn-on process. The proposed method achieves low switching losses. Its effectiveness is demonstrated by experimental results with IGBT modules for 600V and 1200V.
Die anwendungsneutrale und vorsorgliche Verkabelung gibt es bereits seit über 25 Jahren. Die Materie ist zunehmend komplexer geworden. Das ursprünglich für die informationstechnische Vernetzung von Büros vorgesehene Konzept hat sich mit den Jahren auf weitere Anwendungsbereiche, z. B. in Rechenzentren und in industriell oder privat genutzten Bereichen ausgeweitet. Dabei hat jeder Anwendungsbereich neben einem allgemeinen Anforderungsprofil auch ein eigenes, spezifisches Regelwerk. Aufgrund der fortschreitenden Digitalisierung ist zudem eine ständige technologische Anpassung und Weiterentwicklung des Leistungsvermögens vonnöten. Vor diesem Hintergrund wird es zunehmend schwierig, die umfangreichen Normenwerke zu lesen, im Zusammenspiel zu begreifen und optimal anzuwenden.
Und genau hier setzt das Buch an! In dem vorliegenden Buch wird die Kommunikationskabelanlage von der Idee über die Planung, die Spezifizierung, Realisierung, Inbetriebnahme bis hin zur Wartung anschaulich und im Zusammenhang erläutert. Kernstück ist die Vorstellung und Beschreibung der aktuellen Normenreihen DIN EN 50173 (VDE 0800-173) und DIN EN 50174 (VDE 0800-174). Nachdem zunächst auf die Standortvoraussetzungen eingegangen wird, folgen die allgemeinen und spezifischen Anforderungen an informationstechnische Verkabelungen und die verwendeten Komponenten, Kabel bzw. Steckverbinder und zu guter Letzt die Planung, Spezifizierung, Umsetzung und messtechnische Bewertung der Installation. Den Autoren ist es dabei ein Anliegen, nicht nur das Grundverständnis zu den relevanten Anforderungsprofilen zu vermitteln, sondern auch den Blick für den Gesamtzusammenhang, beispielsweise zur Zukunftssicherheit und zum Einfluss unterschiedlicher Umweltbedingungen auf die Auslegung der Verkabelungskomponenten, zu behalten.