Fredrik Bajers Vej 5
Postboks 159 9100 Aalborg
Telefon: 9940 9940
Læs op (få teksten på websitet læst op)
21.09.2017 kl. 13.30 - 16.00
Paula Diaz Reigosa, Department of Energy Technology, will defend the thesis "Short-Circuit Instabilities in Silicon IGBTs and Silicon Carbide MOSFETs".
Short-Circuit Instabilities in Silicon IGBTs and Silicon Carbide MOSFETs
Paula Diaz Reigosa
Professor Francesco Iannuzzo
Associate Professor Huai Wang
Professor Kjeld Pedersen, Dept. of Physics and Nanotechnology, Aalborg University (Chairman)
Professor Ichiro Omura, Kyushu Institute of Technology, Japan
Dr. Caroline Andersson, ABB Corporate Research, Switzerland
Power semiconductor devices are exposed to different type of stresses over their
lifetime, which they need to overcome in order to guarantee long-term reliable operation
up to 20 years or more. One of the most typical stresses that the device must withstand
is related to short-circuit events, which occur randomly during the component’s life.
Silicon-based IGBTs are good candidates for limiting the external current in case of
a short-circuit event, however their robustness is usually limited due to instabilities.
In this Ph.D. thesis, the short-circuit performance of silicon-based IGBTs has mainly
been evaluated, but since Wide-Band Gap (WBG) devices, such as SiC MOSFETs, are
rapidly growing as a potential substitute of silicon-based technologies, its robustness
with respect to short circuit is also addressed.
One of the most important experimental findings, and also the main motivation of
this thesis, is that IGBTs exposed under specific operational conditions suffer from high
frequency gate voltage oscillations (i.e., tens of MHz). Such oscillations are very critical
in case that they become unstable, which will cause the catastrophic damage of the
device. This failure type cannot be explained by any known short-circuit failure mechanism
reported in the literature. Therefore, the aim was to understand the destruction
mechanism that limits the short-circuit capability of the investigated IGBTs. This was
achieved by using a combination of finite-element device simulations and experimental
investigations of 1.2 kV, 1.7 kV, 3.3 kV, IGBTs with different technologies (i.e., planar,
trench and BIGT).
The experimental results demonstrate that the short-circuit ruggedness strongly depends
on the applied DC-link voltage, this means that at low DC-link voltages the
oscillations always occur, but at high DC-link voltages oscillations may not observed.
A sensitivity analysis on the oscillating behavior’s dependence revealed that there are
some factors which help to minimize the oscillations: low gate-emitter voltage, high
temperature and reduced stray inductance.
The root cause of the oscillation mechanism has been found to be as a consequence
of the input capacitance behaving as a time-varying element, leading to an amplification
mechanism involving the external circuit. As a major achievement of this work, it has
been possible to correlate the electric field distortions to gate capacitance variations,
and thus, associate the capacitance variation with charge-storage effects occurring at
the surface of the IGBT. The analysis has demonstrated that the primary cause for
the excess electron density at the surface of the IGBT is the weak electric field in this
region, driven by the Kirk Effect. The carrier drift velocities have a strong impact on
the charge balance of the IGBT, especially at low DC-link voltages. Therefore, the low
drift velocities will cause electron accumulation effects at the surface of the IGBT due
to the weak electric field in this region. On the other hand, at high DC-link voltages,
the carrier drift velocities become saturated across the whole n-base, which means that
the charge-storage effect is no longer present and the input capacitance becomes fixed.
Department of Energy Technology
Pontoppidanstraede 111, auditorium
27.09.2017 kl. 09.00 - 16.30
In honor of Professor Jane Parpart’s many years of contributions to our department, FREIA and CHI are hosting a special workshop titled Gender, Insecurities and Silences during Conflict and Peacebuilding 27th of September, 2017. We have invited a select group of junior and senior scholars across disciplinary boundaries to explore this issue further. We would like to open up this occasion also for other members of the department and university. Please sign up if you are interested in listening to the presentations (session A), take part in the discussions (session B), or both.
27.09.2017 kl. 13.00 - 16.00
Institut for læring og filosofi, Aalborg Universitet og Aalborg Universitetshospital har den glæde at invitere til ph.d.-forsvar ved sygeplejerske MLP Susanne Winther, Forskningsenhed for Klinisk Sygepleje, som forsvarer ph.d.-afhandlingen: FÆLLES FØLGESKAB -ET AKTIONSFORSKNINGSPROJEKT OM PATIENTOVERGANGE FRA INTENSIV TIL STAMAFSNIT
27.09.2017 kl. 16.00 - 18.00
September 27th from 16.00 - 18.00, we invite you to a nation-wide early premiere of Phie Ambo’s new exciting documentary “...when you look away”. The screening will be followed by a debate live-streamed directly from Skylab at DTU, which you can participate in by sending questions via SMS, twitter and facebook.
28.09.2017 kl. 09.00 - 12.00
Open workshop with Dr. Benjamin Schögler, Co-founder and Creative Director at Skoogmusic. Ben is passionate about making music accessible for everyone and was part of the NESTA team that invented SKOOG - an instrument that anyone can play.
28.09.2017 kl. 10.00 - 13.00
Anja Sloth Ziegler, Department of Chemistry and Bioscience will defend her thesis on: "The microbial community in fouling membrane bioreactors: Distribution and diversity of important bacteria"
28.09.2017 kl. 15.00 - 16.30
Præsentation ved henholdsvis professor og lektor ved Institut for Sociologi og Socialt Arbejde på AAU, Annick Prieur og Sune Qvotrup Jensen.
29.09.2017 kl. 09.00 - 17.00
Seminar on animation and visual research dissemination. Learning from state-of-the-art case-studies and ongoing research projects, we will discuss how 2D and 3D-visualisation and animation, narrative structures, and levels of temporal information can be combined in functional animation e.g. for educational or didactic purposes, or in the presentation or development of scientific material.
29.09.2017 kl. 09.00 - 17.30
This workshop brings together scholars from philosophy and history of science to help shed light on epistemological and historical cases of ‘evidence-based’ (or ‘informed’) policy and policymaking.
29.09.2017 kl. 13.00 - 16.00
Klinisk Institut, Aalborg Universitet og Aalborg Universitetshospital har den glæde at invitere til ph.d.-forsvar ved læge Jesper Moesgaard Rantanen, Nyremedicinsk Afdeling, som forsvarer ph.d.-afhandlingen: "Arrhythmias, Heart Rate Variability and Marine n-3 Polyunsaturated Fatty Acids in Patients on Chronic Dialysis"
29.09.2017 kl. 14.00 - 15.30
The seminar is open to all interested researchers!
02.10.2017 kl. 17.00 - 18.00
Mød uddannelsens faglige leder, Dorte Ågård, og hør mere om det faglige indhold. Bliv klogere på uddannelsens perspektiver og relevans i forhold til dit eget arbejdsområde eller interesseområde. Få svar på alle dine faglige og praktiske spørgsmål.
03.10.2017 kl. 13.00 - 16.30
Hør om de væsentligste ændringer, der forventes at komme i bygningsreglement BR18
04.10.2017 kl. 09.00 - 16.00
På dette kurset kan du lære, hvordan gulve, vægge og installationer kan udføres, så kravene i BR15 er overholdt, og så der opnås størst mulig sikkerhed mod skader fra vand og fugt.
04.10.2017 kl. 10.00 - 17.00
Writing has always been a key discipline to master within political sciences and humanities. Today writing articles and getting them published is more important than ever. Be it for the PhD-student using a collection of peer-reviewed and published articles as basis for the PhD, or for the young PhD aiming at a university career.
04.10.2017 kl. 13.00 - 17.00
Klinisk Institut, Aalborg Universitet og Aalborg Universitetshospital har den glæde at invitere til ph.d.-forsvar ved Steen Møller Hansen, Klinisk Epide-miologisk Afdeling, Aalborg Universitetshospital, som forsvarer ph.d.-afhandlingen: Opportunities and Limitations for Provid-ing Early Defibrillation of Out-of-hospital Cardiac Arrest Patients