Ali Nabavi
Visiting Professor
University of Toronto

This seminar gives a brief overview on the static AC/AC power frequency conversion structures and introduces the matrix converter (MC) especially in aircraft application. A matrix converter is an array of controlled semiconductor switches that directly connect each input phase to each output phase, without any intermediate dc link. This direct ac/ac converter provides some attractive characteristics such as: inherent four-quadrant operation; absence of bulky dc-link electrolytic capacitors; clean input power characteristics and increased power density. Therefore MCs have received considerable attention as a good alternative to voltage-source converter (VSC) topology.

However, this topology has not been widely adopted by industry because of 1) its complicated commutation scheme and 2) an elaborate clamp circuit for safe operation. During the last two decades, several methods were proposed to solve these problems. In this seminar a commutation circuit concept for MC is introduced that provides a safe and reliable bidirectional path for the load current during the commutation period and also protects the switches against any overvoltage In this seminar we will review the following topics for a MC considering practical issues.

• Indirect AC-AC Conversion
• Bidirectional Switches and Direct AC-AC Conversion
• Current Commutation
• Input L-C Filter
• Active Filter
• Comparison between MC and back-to-back VSC

Dr. Nabavi is a Senior Member of IEEE and a professional engineer in the Province of Ontario, Canada. He received the B.Sc. and M.Sc. degrees in electrical engineering from Amirkabir University of Technology, Tehran, Iran, in 1987 and 1990, respectively, and the Ph.D. degree in electrical engineering from the University of Toronto, Toronto, ON, Canada, in 1996. Upon graduation he joined the University of Mazandaran, Babol, Iran as an assistant professor in the Department of Electrical and Computer Engineering. Since then he has been actively engaged in research and development in the general area of power electronics, FACTS controllers and teaching and supervising of graduate students. He was elevated to the rank of associate professor in 2003. Since 2004, he has been with the Energy Systems Group, Department of ECE, University of Toronto, as a visiting professor and has been actively collaborating on several research projects with various utility and aerospace industries including ABB and Honeywell. His research interests include analysis, operation and control of power electronics in power systems.