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Kongens Lyngby, Denmark

Hernandez J.C.,Technology University of Denmark | Petersen L.P.,Technology University of Denmark | Andersen M.A.E.,Technology University of Denmark | Petersen N.H.,Grundfos A S
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2014

This paper presents a guide on characterizing state-of-the-art silicon superjunction (SJ) devices in the 600V range for single phase power factor correction (PFC) applications. The characterization procedure is based on a minimally inductive double pulse tester (DPT) with a very low intrusive current measurement method, which enables reaching the switching speed limits of these devices. Due to the intrinsic low and nonlinear capacitances in vertical SJ MOSFETs, special attention needs to be paid to the gate drive design to minimize oscillations and limit the maximum at turn off. This paper investigates the latest SJ devices in order to set a reference for future research on improvement over silicon (Si) attained with the introduction of wide bandgap devices in single phase PFC applications. The obtained results show that the latest generation of SJ devices set a new benchmark for its wide bandgap competitors. © 2014 IEEE.

Ramsay J.,University of Aarhus | Dupont S.,University of Aarhus | Johansen M.,University of Aarhus | Rishoj L.,Technology University of Denmark | And 3 more authors.
Optics Express | Year: 2013

Using femtosecond upconversion we investigate the time and wavelength structure of infrared supercontinuum generation. It is shown that radiation is scattered into higher order spatial modes (HOMs) when generating a supercontinuum using fibers that are not single-moded, such as a step-index ZBLAN fiber. As a consequence of intermodal scattering and the difference in group velocity for the modes, the supercontinuum splits up spatially and temporally. Experimental results indicate that a significant part of the radiation propagates in HOMs. Conventional simulations of super-continuum generation do not include scattering into HOMs, and including this provides an extra degree of freedom for tailoring supercontinuum sources. © 2013 Optical Society of America.

Hviid C.A.,Technology University of Denmark | Svendsen S.,Technology University of Denmark
Energy and Buildings | Year: 2013

An experimental study is reported in this paper for a diffuse ceiling ventilation concept. The analyses were carried out with two different porous surfaces mounted in a suspended ceiling: perforated tiles of aluminium and of gypsum. Ventilation air was supplied above the suspended ceiling effectively creating a plenum for air distribution. The experiments were carried out in a climatic chamber and documented an air change efficiency equal to fully mixed conditions with a pressure drop of 0.5-1.5 Pa and with no evidence of thermal discomfort. The magnitude of the pressure drop was enough to sustain the pressure of the plenum and ensure uni-directional airflow through the ceiling. Consequently only reverse flow of insignificant magnitude was observed which has a positive impact on the hygiene of the plenum. Furthermore, the measurements documented that the ceiling acts as a radiant cooling surface which increases the potential and applicability of the concept. Risk of thermal discomfort was not disclosed but the study did show evidence of large fluctuating air movements which could stem from transient behaviour creating sensations of draught to the occupants. © 2012 Elsevier B.V. All rights reserved.

Niemann H.,Technology University of Denmark | Poulsen N.K.,Technology University of Denmark
Proceedings of the American Control Conference | Year: 2015

The aim of this paper is to present a method for estimation of parametric faults in closed-loop systems. The key technology applied in this paper is coprime factorization of both the dynamic system as well as the feedback controller. Using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization, it is shown that a certain matrix transfer function, the fault signature matrix, is an LFT (linear fractional transformation) of the parametric faults. Further, for limit parametric faults, the fault signature matrix transfer function can be approximated with a linear matrix function of the parametric faults. © 2015 American Automatic Control Council.

Hansen S.,Technology University of Denmark | Ravn O.,Technology University of Denmark
16th International Conference on Research and Education in Mechatronics, REM 2015 - Proceedings | Year: 2015

Experiences from a new course in mechatronics at Technical University of Denmark are conveyed in this paper. The course is supposed to teach students enrolled in the bachelor degree in electrical engineering some fundamental knowledge about mechanics and to teach students enrolled in the bachelor degree in mechanical engineering fundamentals about electronics. Furthermore the course uses project work as a method to keep the students actively participating and in part have them teach each other the subjects. The general course plan is presented and the reasoning behind the course structure is discussed in the paper, together with a brief look at the student's reactions in form of data from the course evaluation. © 2015 Deutsche Gesellschaft für Mechatronik.

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