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Next-Generation SiC/GaN Three-Phase Variable Speed Drive PWM Inverter Concepts

Johann W. Kolar, Michael Antivachis, Mattia Guacci and Dominik Bortis

Brief Introduction:

    Next-generation variable speed drive (VSD) systems should feature high power density, not require shielded motor cables, offer high input and/or output voltage/motor speed range, ensure low motor power losses and/or applicability of conventional low-cost motor technology, and prevent dv/dt-related motor insulation stresses and bearing currents, as well as reflections on long motor cables.

    This Tutorial will first discuss state-of-the-art VSD systems, define future requirements and highlight challenges originating from employing latest ultra‐fast switching wide-bandgap (WBG) power semiconductors (GaN and SiC), which are a main enabling technology for further improving VSD performance. Next, different inverter output filter structures providing a continuous motor voltage waveform and/or preventing PWM-related effects, as well as the filter design procedure and control, will be presented. Furthermore, examples of recently introduced commercial WBG VSD systems with output filter will be described.

    Next, advanced PWM inverter bridge-leg topologies, e.g. a quasi-two-level operated five-level flying capacitor approach, will be discussed and new voltage DC-link and current DC‐link inverter topologies featuring buck‐boost functionality and a continuous sinusoidal output voltage will be presented, including experimental results of ultra‐compact hardware demonstrators.

    Final considerations will be on the fast and highly accurate experimental evaluation of SiC/GaN power semiconductors, ceramic filter capacitors and filter inductor magnetic core materials, as required for the design of next-generation very high switching frequency and highly compact WBG inverter systems. Furthermore, the advantages and challenges of a physical integration of motor and inverter will be highlighted and topics of current research on advanced VSD systems at the Power Electronic Systems Laboratory of ETH Zurich will be presented.

image.pngJohann W. Kolar (kolar @lem.ee.ethz.ch) is a Fellow of the IEEE and has received  his PhD degree (summa cum laude) from the Vienna University of Technology,  Austria. He is currently a Full Professor and the Head of the Power Electronic  Systems Laboratory at the Swiss Federal Institute of Technology (ETH) Zurich. He  has proposed numerous novel PWM converter topologies, modulation and control  concepts and has supervised 70+ Ph.D. students. He has published 880+ scientific  papers in international journals and conference proceedings and has filed 190+ patents. He received  numerous awards, incl. 29 IEEE Transactions and Conference Prize Paper Awards, the 2016 IEEE William  E. Newell Power Electronics Award, and 2 ETH Zurich Golden Owl Awards for excellence in teaching. The  focus of his current research is on ultra-compact / ultra-efficient SiC and GaN converter systems, solidstate transformers, advanced three-phase inverter concepts for variable speed motor drives, ultra-high  speed and bearingless motors / actuators, and design automation in power electronics/mechatronics.

image.pngMichael Antivachis (antivachis@lem.ee.ethz.ch) received the B.Sc. degree in  electrical engineering from National Technical University of Athens (NTUA) in  2014 and the M.Sc. degree in energy science and technology from ETH Zürich  in 2016. Since June 2016 he is with the Power Electronic Systems Laboratory of  ETH Zurich as a Ph.D. candidate. His research interests include high-speed  motor drive systems for commercial applications, efficient inverters topologies  in a small form factor employing wide-bandgap power devices and low EMI emission profile  converters.

image.png  Mattia Guacci (guacci@lem.ee.ethz.ch) studied Electronic Engineering at the  University of Udine, Italy where in July 2013 and in October 2015 he received  his B.Sc. summa cum laude and his M.Sc. summa cum laude, respectively. In  2014 he was with Metasystems SpA in Reggio nell’Emilia, Italy working on onboard battery chargers for electric vehicles. In November 2015 he joined the  Power Electronic Systems Laboratory (PES) at ETH Zurich as a scientific  assistant investigating innovative inverter topologies. In September 2016 he  started his Ph.D. at PES focusing on advanced power electronics concepts for future aircraft and  electric vehicle applications.

image.pngDominik Bortis(bortis@lem.ee.ethz.ch) received the M.Sc. degree in electrical  engineering and the Ph.D. degree from the Swiss Federal Institute of  Technology (ETH) Zurich, Switzerland, in 2005 and 2008, respectively. In May  2005, he joined the Power Electronic Systems Laboratory (PES), ETH Zurich, as  a Ph.D. student. From 2008 to 2011, he has been a Postdoctoral Fellow and  from 2011 to 2016 a Research Associate with PES, co-supervising Ph.D.  students and leading industry research projects. Since January 2016 Dr. Bortis is heading the newly  established research group Advanced Mechatronic Systems at PES.