Events at Department of Energy Technology

Guest lectures by Jih-Sheng (Jason) Lai and Antonio J. Marques Cardoso


15.10.2018 kl. 10.00 - 12.00


There will be two guest lectures on October 15, 2018 prior to the PhD defence of Haoran Wang


Power Electronics Design Challenges with Wide Bandgap Devices


Jih-Sheng (Jason) Lai, Virginia Polytechnic Institute and State University, USA


10:00 - 11:00


Wide-bandgap (WBG) devices are known for their fast switching speed, but to push to mega-hertz switching for high power applications, there is a need for new knowledge. The main challenges are parasitic effects due to fast di/dt and dv/dt. This presentation will address major critical issues in WBG based converter in mega-hertz switching. For a conventional voltage source converter, the parasitic inductance in the phase leg can introduce a large voltage spike that false-triggers the opposite side or other phase leg switches. This phenomenon is well known with traditional silicon devices, but it is much more severe with WBG devices. Traditional solution in silicon-based converters is to place a large power-ground plane to reduce the loop inductance. In WBG-based converters, this ground plane will add capacitance on to the junction and thus increasing the switching loss. An interesting example is the asymmetrical switching cycle caused by the printed-circuit-board (PCB) layout. From a phase-leg output to the transformer terminal, the distance is in tenth of nano-henry range. The parasitic inductances from individual phase-leg outputs connecting to the transformer can be as much as twice different, and thus causing severe asymmetrical output pulse when switching at mega-hertz frequencies.

About the lecturer

Jih-Sheng (Jason) Lai received M.S. and Ph.D. degrees in electrical engineering from the University of Tennessee, Knoxville, in 1985 and 1989, respectively. In 1989, he joined the Electric Power Research Institute (EPRI).  From 1993, he worked with the Oak Ridge National Laboratory as the Power Electronics Lead Scientist.  He joined Virginia Tech in 1996. Currently he is James. S. Tucker Endowed Chair Professor and the Director of Future Energy Electronics Center (FEEC). He has published more than 400 refereed technical papers and 2 books.

He holds 25 U.S. patents in the area of high power electronics and their applications. He received several distinctive awards including Technical Achievement Award in Lockheed Martin Award Night and 12 Best Paper Awards from IEEE conferences and journals. His student teams won the First Prize Award in Texas Instruments Analog Design Competition in 2011, the Grand Prize Award from International Future Energy Challenge in 2013, and the Top Three Award from the Google Little Box Challenge in 2016. Dr. Lai is an IEEE Fellow and the recipient of 2016 IEEE Industry Applications Society Gerald Kliman Innovation Award. He is the Founding Chairs of Asian Conference on Energy, Power and Transportation Electrification (ACEPT-2016) and IEEE Future Energy Challenge (IFEC-2001), General Chairs of IEEE COMPEL 2000 and IEEE APEC 2005. Currently he serves as the Publications Chair for IEEE Transportation Electrification Community, Editorship for IEEE Journal of Emerging and Selected Topics in Power Electronics (JESTPE) and MDPI Journal on Energies. 



Condition Monitoring and Diagnostics of Electrical Machines and Drives – Case Histories

Guest Lecturer

Antonio J. Marques Cardoso, University of Beira Interior (UBI), Portugal


11:00 - 12:00


Electric motors and drives are the backbone of the industry. They can be found in power plants, wind farms, pumps, industry applications, cranes, conveyors, belts, mills, transportation and many other applications. So, it is to be expected that electrical machines and drives are related to huge financial variables as well as safety and reliability. Although electrical machines and drives are robust devices, faults may appear and interrupt their working life cycle in many ways. Therefore, the use of condition monitoring and diagnostic techniques becomes crucial in order to be able to detect the faults at an early stage of development.

This seminar presents the industrial experience on the application of the Park’s Vector Approach for the condition monitoring and diagnostics of electrical machines and drives. The case histories to be presented concern the practice of fault diagnosis in large three-phase induction motors (up to 5 MW) operating in industry, such as, power generation plants and cement mills.

about the lecturer

Antonio J. Marques Cardoso (S’89, A’95, SM’99) received the Dipl. Eng., Dr. Eng., and Habilitation degrees from the University of Coimbra, Coimbra, Portugal, in 1985, 1995, and 2008, respectively, all in electrical engineering. From 1985 to 2011, he was at the University of Coimbra, where he was the Director of the Electrical Machines Laboratory. Since 2011, he has been with the University of Beira Interior (UBI), Covilhã, Portugal, where he is Full Professor in the Department of Electromechanical Engineering and Director of CISE – Electromechatronic Systems Research Centre ( He was Vice-Rector of UBI from 2013 to 2014. He is the author of the book Fault Diagnosis in Three-Phase Induction Motors (Coimbra Editora, 1991), in Portuguese, and approximately 400 papers published in technical journals and conference proceedings. His current research interests include fault diagnosis and fault tolerance in electrical machines, power electronics, and drives. Prof. Marques Cardoso was the General Chair of the 10th IEEE International Symposium on Diagnostics for Electric Machines, Power Electronics, and Drives, Guarda, Portugal, in 2015, and of the 20th International Congress and Exhibition on Condition Monitoring and Diagnostic Engineering Management, Faro, Portugal, in 2007. He is currently an Associate Editor of the IEEE Transactions on Industry Applications, IEEE Transactions on Industrial Electronics, IEEE Transactions on Power Electronics, IEEE Journal of Emerging and Selected Topics in Power Electronics, and of the Springer International Journal of Systems Assurance Engineering and Management. 



Department of Energy Technology


Pontoppidanstræde 105, room 4.127