Reliability in Power Electronic Systems

EPE 2015 ECCE Europe
Geneva, Switzerland, 7-10 September 2015
Tutorial: Reliability in Power Electronic Systems
Instructors: Frede Blaabjerg, Francesco Iannuzzo, Huai Wang, Ke Ma
Center of Reliable Power Electronics (CORPE), Aalborg University, Denmark
1. Scope and Benefits
Advances in power electronics enable efficient and flexible processing of electric power in the
application of renewable energy sources, electric vehicles, adjustable-speed drives, etc. More and
more efforts are devoted to having better power electronic systems in terms of reliability to ensure
high availability, long lifetime, sufficient robustness and low maintenance cost. Today customers of
many power electronic products expect up to 20 years of lifetime and they also want to have a “failure
free period” and all with focus at the financials. However, the reliability predictions are still dominantly
according to outdated models and terms, such as MIL-HDBK-217F handbook models, mean-time-to
failure (MTTF), and mean-time-between-failures (MTBF).
The emphasis of this tutorial is to give a framework on the design for reliability of power electronic
systems and the recent research activities and paradigm shifts in this research area.
It will cover the
reliability requirements in different industry sectors, reliability and lifetime of IGBT modules and
capacitors used in power electronic converters, testing of power components, and the specific design
for reliability procedure for power electronic systems. Study cases on mission profile based design of
photovoltaic inverters and wind power converters, and active thermal control and condition monitoring
of power converters are also discussed. The approaches presented in the tutorial are also the
common interest for the companies involved in the Center of Reliable Power Electronics (CORPE) at
Aalborg University (http://www.corpe.et.aau.dk/). The tutorial will also present the views of the
instructors on the future research opportunities in the area of reliability of power electronics.
2. Tutorial Contents
The tutorial will be organized in four main parts:
a) Introduction to modern reliability and the challenges in power electronics
The Cost of poor Quality and Reliability is an important parameter when optimizing new designs or
improve products. What are the industries expectations to the design engineers in the future? Why
FIT and MTBF cannot be used to reach such goals? Some methods have become obsolete and a lot of
new skills are important. Some of these methods and needed attitudes will be presented. To reach
the intention of the managers we have to use their language. How Cost of poor Reliability can be
calculated? It is very important to be sure that the adopted reliability models and quantitative figures
are related to the real world. In this part, different aspects of improving the reliability of the power
converters are mapped. Finally, the challenges and opportunities to achieve more reliable power
electronic systems are addressed.
b) Reliability-critical components in power electronics
The wear out failure mechanisms of reliability critical components, e.g., IGBT modules and capacitors,
are discussed. The corresponding lifetime prediction models (both analytical models and
physics-of-failure based models) and their respective limitations are also discussed. Further on, a
reliability prediction tool is demonstrated for the reliability prediction of components used in power
electronic systems, e.g., PV inverters and multi-MW wind power converters.
EPE 2015 ECCE Europe
Geneva, Switzerland, 7-10 September 2015
c) Failure mechanisms and testing of semiconductor power devices operated at the edge of SOA
Reliability engineers look more and more attentively to abnormal events, which considerably and
unpredictably reduce the real lifetime of power components. The basic physical mechanisms involved
in the failure of semiconductor power devices when operated under highly stressing electrical
conditions (short circuit, overload, overvoltage, etc.) will be presented. The attention is focused on
unstable phenomena which may cause a strongly localized power dissipation in the device structure
and the consequent device failure. The test of the devices under these conditions can be conveniently
performed in a non-destructive way. In this approach, the Device Under Test (DUT) is overstressed in
presence of a protection circuit which is able to quickly zero the energy dissipated by the DUT at the
occurrence of a potentially destructive unstable condition hence, in many cases, to prevent its failure.
The tutorial describes the main design principles and challenges of such an approach. The basic
instabilities occurring during the highly stressing operations of the power devices are presented and
a particular attention is devoted to the precursors, which precedes these instabilities and help in
performing the protection action.
d) Real time monitoring and prediction in components and systems
The main focus is on identifying methods for the real time (on-line) detection of the lifetime (wear-out)
state of the power transistor (or power diode) by monitoring various relevant (thermal, electrical,
optical etc.) sensor signals. The goal is to make possible the desired real time detection during
normal operation of a power converter. The developed methods will most likely include sensors for
measuring physical quantities (such as voltages, currents and temperatures), communication and
software based models and signal processing. Some of the features could be integrated into the gate
driver circuit for power devices in order to get access to the ‘hot’ (high voltage) side of the power
converter in an economical way. Active power control methods based on real time monitoring will be
also discussed.
3. Tutorial Time Schedule (Can be adapted to fit the conference schedule)
Monday, September 7th, 2015 (Location: CICG, Geneva)
08:00 - 09:30
Registration for Tutorials
09:30 – 11:00
Introduction to modern reliability and the challenges in power electronics
11:00 - 11:30
Coffee break
11.30 – 13:00
Reliability-critical components in power electronics
13:00 - 14:00
Lunch break
14:00 - 15:30
Failure mechanisms and testing of semiconductor power devices
operated at the edge of SOA
15:30 - 16:00
Coffee break
16:00 – 17:30
Real time monitoring and prediction in components and systems, and Q&A
4. Who Should Attend
Researchers and engineers who seek for the basic knowledge for entering in this field, ranging from
component level to system level, from physic of failure to statistical analysis. Prerequisite is basic
power electronics and statistical concepts.
EPE 2015 ECCE Europe
Geneva, Switzerland, 7-10 September 2015
5. About the Instructors
Frede Blaabjerg (F’03) is currently a Professor with the Department of Energy
Technology and the Director of Center of Reliable Power Electronics (CORPE),
Aalborg University, Denmark. He has intensive research work on power electronics
and its applications in motor drives, wind turbines, PV systems, harmonics, and the
reliability of power electronic systems. He has held more than 300 lectures national
and international, most of them in the last decade are invited and as keynotes at
conferences, covering various topics on power electronics, including the reliability. He was a
Distinguished Lecturer for the IEEE Power Electronics Society from 2005 to 2007 and for the IEEE
Industry Applications Society from 2010 to 2011. He has contributed more than 800 journal and
conference papers, many of which in the last four years are relevant to the reliability of power
electronic components, converters and systems. Dr. Blaabjerg received the IEEE William E. Newell
Power Electronics Award in 2014, the IEEE PELS Distinguished Service Award in 2009, the
Outstanding Young Power Electronics Engineer Award in 1998, and 15 IEEE Prize Paper Awards. He
served the Editor-in-Chief of the IEEE Transactions on Power Electronics from 2006 to 2012.
Francesco Iannuzzo (SM’12) is full professor of Reliable Power Electronics at the
Aalborg University, Denmark, where he is also part of CORPE (Center Of Reliable
Power Electronics). He earned his M.Sc. degree cum laude in 1997 and his Ph.D.
degree in Electronics and Information Engineering from the University of Naples,
Italy, in 2001, with a study on the reliability of power MOSFETs during diode
operations. He is primarily specialized in the field of power device modelling. He
has been Researcher since 2000 with University of Cassino, Italy, where he became Aggregate
professor in 2006 and Associate professor in 2012. He is author or co-author of more than 90
publications on journals and international conferences. His research interests are in the field of
reliability of power devices, including against cosmic rays, power device failure modelling and testing
of power modules up to MW-scale under extreme conditions, like overvoltage, overcurrent and
over-temperature. Prof. Iannuzzo was the Technical Programme Committee Chair in two editions of
ESREF, the European Symposium on Reliability and Failure analysis. He is a senior member of the
IEEE (Reliability Society, Industrial Electronic Society and recently Industrial Application Society) and
of AEIT (Italian Electric, Electronic and Telecommunication Association).
Huai Wang is currently an Assistant Professor with the Center of Reliable Power
Electronics (CORPE) in the Department of Energy Technology, Aalborg University,
Denmark. His current research interests include the reliability of power electronic
systems, reliability of capacitors in power converters, time-domain control of
power converters, and high-voltage DC-DC converters. He co-lectured a PhD
course on Reliability in Power Electronic Systems at Aalborg University and is an
invited speaker at ECPE workshops and tutorial instructors at several leading power electronics
conferences. He has contributed a number of journal papers, including several concept papers on the
design for reliability of power electronic systems.
Dr. Wang received his PhD degree from the City
University of Hong Kong, Hong Kong, in 2012, and B. E. Degree from Huazhong University of Science
and Technology, China, in 2007. He was a Visiting Scientist with the ETH Zurich, Zurich, Switzerland,
EPE 2015 ECCE Europe
Geneva, Switzerland, 7-10 September 2015
from August to September, 2014 and with the Massachusetts Institute of Technology (MIT), Cambridge,
MA, USA, from September to November, 2013. He was with the ABB Corporate Research Center,
Baden, Switzerland, in 2009. He serves the Guest Associate Editor of the IEEE Transactions on Power
Electronics and Guest Editorial Board of Microelectronics Reliability on special Issue topics relevant to
reliability in power electronics.
Ke Ma is currently an Assistant Professor at Aalborg University with the Center of
Reliable Power Electronics (CORPE), where he is the leader of working package 4
involving reliability modelling and design tools development. His current research
interests are various aspects of power electronics technology including reliability in
the application of renewable energy systems. In the last 3 years he has contributed
more than 40 journal and conference papers including 3 book chapters in the field
of power electronics and reliability. He is one of the lecturers for an Industrial/PhD
course on “Reliability in Power Electronic Systems” at Aalborg University, and was invited as speaker
at the European Center for Power Electronics (ECPE) workshop on “Power Electronics Packaging”.
He was also a speaker in the Tutorial Session in IEEE Energy Conversion Congress and Expo (ECCE)
2014. Dr. Ma received the B.Eng. and M.Sc. degrees from Zhejiang University, China and PhD degree
from Aalborg University, Denmark. He was the receiver of a few IEEE prized paper awards. He serves
as the Associate Editor on IEEE Transaction on Industry Application and the Founder of an IEEE
Student Branch at Denmark Section.
6. Contact Details
Huai Wang
Department of Energy Technology, Aalborg University
eMail: hwa@et.aau.dk
Tel: +45 9940 3816