Events at Department of Energy Technology

Guest lecture by Professor Thomas M. Jahns


11.01.2018 kl. 11.00 - 11.01.2018 kl. 12.00


There will be a guest lecture on January 11


Can Current-Source Inverters Succeed in Future Machine Drives?


Professor Thomas M. Jahns, IEEE Fellow, Co-Director of the Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC), The University of Wisconsin, Madison, USA.


11:00 - 12:00


It has been common knowledge for the past 35 years that PWM current-source inverters (PWM-CSIs) are poorly-suited for most commercial adjustable-speed drives due to a combination of their disadvantages including poor efficiency and high parts count when using silicon MOS-gated power switches.  But will this continue to be true in the future?  The objective of this presentation is to make the case for a revival of interest in PWM-CSIs for future machine drives, with particular attention given to the advantages they offer for PM machine drives.   More specifically, the absence of free-wheeling diodes in CSIs provides the basis for significantly reducing the risks associated with terminal short-circuit faults in PM machines which are often cited as one of the most important drawbacks of PM machines in demanding applications.  The growing maturity of wide-bandgap (WBG) power semiconductors is playing a key role in spurring this renewed interest in PWM-CSIs because of: 1) special advantages that CSIs offer for handling much higher switching frequencies by suppressing switching losses, EMI, and dv/dt-induced voltage build-up at the machine terminals; and 2) intriguing opportunities opened by GaN switches, in particular, for the development of low-loss reverse-voltage-blocking switches that are critical to the success of future PWM-CSIs.  The presentation will close with a discussion of the special appeal of PWM-CSIs in future integrated motor drives and the remaining technical challenges that must be overcome for these inverters to rise again from the ashes.

About the lecturer

Thomas M. Jahns received his bachelors, masters, and doctoral degrees in electrical engineering from MIT, Cambridge, MA (USA).

Dr. Jahns joined the faculty of the University of Wisconsin – Madison (USA) in 1998 as a Grainger Professor of Power Electronics and Electric Machines in the Department of Electrical and Computer Engineering.  He is a Co-Director of the Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC), a university/industry consortium with over 85 international sponsors. 

Prior to coming to UW-Madison, Dr. Jahns worked at GE Corporate Research and Development in Niskayuna, NY (USA) for 15 years, where he pursued new power electronics and motor drive technology in a variety of research and management positions. His current research interests at UW-Madison include multiple forms of electrified propulsion, renewable energy systems, microgrids, and energy storage.

Dr. Jahns is a Fellow of IEEE.  He received the 2005 IEEE Nikola Tesla Technical Field Award “for pioneering contributions to the design and application of AC permanent magnet machines”.  Dr. Jahns is a Past President of the IEEE Power Electronics Society and the recipient of the 2011 Outstanding Achievement Award presented by the IEEE Industry Applications Society.  He was elected to the US National Academy of Engineering in 2015.




Department of Energy Technology


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