Hiroyuki Ohsaki / Professor / Division of Transdisciplinary Sciences
Department of Advanced Energy / / Applied Superconductivity and Electromagnetic Energy Engineering

Career Summary
1983: Graduated, Department of Electrical Engineering, Faculty of Engineering, The University of Tokyo
1988: Doctor of Engineering from The University of Tokyo (Electrical Engineering)
1988: Research Associate, School of Engineering, The University of Tokyo
1989: Lecturer, School of Engineering, The University of Tokyo
1991-93: Guest Researcher, Institute of Electrical Machines, RWTH Aachen, Germany
1993: Associate Professor, School of Engineering, The University of Tokyo
1999: Associate Professor, Graduate School of Frontier Sciences, The University of Tokyo
2004: Professor, Graduate School of Frontier Sciences, The University of Tokyo
Educational Activities
Graduate School: Applied Electromechanical Dynamics, Electromagnetic Environmental Engineering, Advanced Electric Machinery II
Undergraduate School: Applied Superconductivity in Power Engineering
Research Activities
For the efficient use of electric energy and advanced application of electromagnetic phenomena, we are studying high-performance electromagnetic energy equipment and systems that utilize advanced materials such as permanent magnets and superconductors. Our research is based on various principles, including electromagnetics, applied superconductivity, and electric machinery, and is carried out through experiments, theoretical studies and numerical simulations. The applications of our research cover fields of electric power, transportation, manufacturing and medical industries.

1) Applied superconductivity?electromagnetic phenomena and application systems

For the practical applications of high-temperature superconductors (YBa2Cu3Ox, (RE)Ba2Cu3Ox, etc.), which are in the superconducting state at liquid nitrogen temperature (77 K), in electric power, transportation, industrial and medical fields, electromagnetic and thermal characteristics of the materials and their application systems have been studied. In particular, we have been interested in the application of high-temperature superconducting bulk and thin films to energy equipment. The electromagnetic characteristics, such as electromagnetic force and current-carrying performance have been investigated through experiments and numerical analysis.

Electromagnetic phenomena in superconductors
Electromagnetic phenomena in superconductors

Characteristic analysis of superconducting application devices have been performed and the following are examples of potential applications that have been studied: bulk superconductors as a strong magnetic flux source, superconducting fault current limiters for highly reliable and flexible operation of electric power systems, superconducting magnetic energy storage systems (SMES), superconducting flywheel energy storage systems, superconducting motors, superconducting magnetic levitation systems, new MRI techniques for imaging dielectric properties of biological tissues.

Superconducting equipment and systems
Superconducting equipment and systems

2) Advanced electromagnetic energy conversion equipment and systems

Progress in material technologies such as permanent magnets and superconductors has improved performance of equipment and systems for electromagnetic force use and has generated new application fields, such as vertical transportation and multi-dimensional drive. We have studied several types of linear motors and actuators, and magnetic levitation systems by experimental and numerical analysis methods, such as planar actuators for direct drive and precise positioning on a two-dimensional plane, numerical analysis of eddy currents in electric conductors moving at a high speed in a magnetic field, analysis of vehicle dynamics of maglev systems, linear motor systems for factory automation, and industrial applications of linear motors and magnetic levitation technology.

Small planar actuator and maglev vehicle dynamics analysis
Small planar actuator and maglev vehicle dynamics analysis

1) H. Ohsaki, T. Shimosaki and N. Nozawa: Pulse field magnetization of a ring-shaped bulk superconductor, Superconductor Science and Technology, Vol. 15, No. 5, pp. 754-758 (2002).
2) Y. Ichiki and H. Ohsaki: Numerical analysis and design of fault current limiting elements using large-size YBCO thin films, Physica C: Superconductivity, Vol. 463-465, pp. 1168-1171 (Oct. 2007).
3) Y. Ueda and H. Ohsaki: Fundamental Characteristics of a Small Actuator with a Magnetically Levitated Mover, The Fourth Power Conversion Conference (PCC Nagoya 2007), IEEJ-IAS and IEEE-IAS, LS2-3-2 (April 4, 2007).
Other Activities
Institute of Electrical and Electronics Engineers (IEEE)
Institute of Electrical Engineers of Japan (IEEJ)
Cryogenic Society of Japan (CAJ)
Japan Society of Applied Electromagnetic and Mechanics (JSAEM)
Japan Society of Plasma Science and Nuclear Fusion Research (JSPF)
Future Plan
We plan to further advance the state of research for the practical application of superconducting technology, which is expected to be one of the innovative technologies in energy engineering. We are clarifying the relation between electromagnetic phenomena in superconductors and system characteristics of superconducting equipment and developing innovative superconducting equipment with highly improved performance.
We are studying direct drive by electric motors and actuators, which can improve the system performance, including drive characteristics, and developing linear motors and magnetic levitation technology.
Messages to Students
Performance improvement of electric equipment used for generation, transmission and utilization of electric energy is increasingly required. Environmental requirements such as reduction of carbon dioxide emissions and improvement of electric power quality are of increasing importance. To achieve solutions to these problems, the research and development of electromagnetic equipment for electric power, transportation and industrial fields needs young researchers and engineers. I hope you will become interested in issues of energy, environment, society, and economics, and will choose to study electrical machines using new materials and technologies with optimal design. You should aim to be actively involved in everything.