ABB Distinguished Lecturer: Hirofumi Akagi

Photo of Hirofumi Akagi

Hirofumi Akagi
Professor, Electrical and Electronic Engineering
Tokyo Institute of Technology

Medium-Voltage Power Converters and their Applications

Hirofumi Akagi , Professor, Electrical and Electronic Engineering
Tokyo Institute of Technology

Hirofumi Akagi spoke on Friday, May 25th, 2012 at 2:00PM in the McKimmon Center

This talk has an intensive discussion on the modular multilevel cascade converter (MMCC) family for medium-voltage grid connection and motor drives.

The MMCC family is based on cascade connection of multiple bidirectional-chopper cells or multiple single-phase full-bridge cells. This converter family is classified from circuit configuration as follows; the single-star bridge-cells (SSBC), the single-delta bridge-cells (SDBC), the double-star chopper-cells (DSCC), and the double-star bridge-cells (DSBC). The term MMCC corresponds to a family name in a person while, for example, the term SSBC corresponds to a given name. Therefore, the term "MMCC-SSBC" can identify the circuit configuration without any confusion. Among the four circuit configurations, both SSBC and DSCC are the most practical than the others in terms of cost and performance, although a distinct difference exists in application between the SSBC and the DSCC.

The PWM-based SSBC is applicable to static synchronous compensators (SATCOMs) for positive-sequence reactive-power control while the PWM-based SDBC is applicable to SATCOMs for negative-sequence reactive-power control or voltage-flicker compensation of large-scaled ac arc furnaces. Both systems can be connected to medium-voltage utility and industrial distribution systems. In addition, the PWM-based SSBC is suitable to large-scaled battery energy storage systems. These are expected to play an important role in the so-called "smart grid" that is characterized by massive penetration of wind power and photovoltaic systems in the near future.

The PWM-based DSCC is suitable, not only HVDC and BTB system for transmission systems, but also to medium-voltage motor drives without regenerative braking for fans, blowers and compressors. Experimental results are shown from three different downscaled models for a 10-kVA STATCOM, a 20-kWh battery energy storage system, and a 15-kW motor drive, all of which were designed and constructed in the speaker's laboratory.

Hirofumi Akagi received the B. S. degree from the Nagoya Institute of Technology, Nagoya, Japan, in 1974, and the M. S. and Ph. D. degrees from the Tokyo Institute of Technology, Tokyo, Japan, in 1976 and 1979, respectively, all in electrical engineering. In 1979, he joined the Nagaoka University of Technology, Nagaoka, Japan, as an Assistant Professor and then became an Associate Professor in the department of electrical engineering. From 1991 to 1999, he was a Professor in the department of electrical engineering at Okayama University, Okayama, Japan. Since January 2000, he has been Professor in the department of electrical and electronic engineering at the Tokyo Institute of Technology.

His research interests include power conversion systems, motor drives, active and passive EMI filters, high-frequency resonant inverters for induction heating and corona discharge treatment processes, and utility applications of power electronics such
as active filters, self-commutated BTB (back-to-back) systems, and FACTS (flexible ac transmission systems) devices. He has authored and coauthored more than 100 IEEE Transactions papers and two invited papers published in Proceedings of the IEEE in 2001 and 2004. The total citation index for all his papers in Google Scholar is more than 16,000 times. He has made presentations many times as a keynote or invited speaker internationally.

He received five IEEE Transactions Prize Paper Awards. He is also the recipient of the 2001 IEEE William E. Newell Power Electronics Award, the 2004 IEEE IAS Outstanding Achievement Award, the 2008 IEEE Richard H. Kaufmann Technical Field Award, and the 2012 IEEE PES Nari Hingaroni Custom Power Award.

Dr. Akagi served as the President of the IEEE Power Electronics Society for 2007-2008.