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A New Breakthrough of Superconducting propulsion Motor

Last Update : 2018-08-03 15:59

New challenge of superconducting motor: A prototype type machine for a large
scale electric machine using HTS bulk superconductors

 National University Corporation, Tokyo University of Marine Science and
Technology(TUMSAT; Minato-ku, Tokyo, President Toshio Takeuchi), ABB Corporate
Research (ABB, ASEA Brown Boveri Ltd.; Ulrich Spiesshofer, CEO), and Nippon
Steel & Sumitomo Metal Corporation (NSSMC; Chiyoda-ku, Tokyo, President
Kosei Shindo) have successfully developed a new type of superconducting
synchronous motor. Till now, most superconducting motors have been assembled
with a superconducting coil wound by using a superconducting wire. In place of the
wound coil, TUMSAT and ABB have successfully developed a demonstration
prototype machine designed for 30 kW output. They have employed a large size
magnet composed of high quality, high-temperature superconducting (HTS) bulks
developed by NSSMC (QMG*). The design structure enables scaling-up to Mega-
Watt output machines, motors or generators, enabling an innovative approach for
future electric ships, off-shore wind power generation system, electrical aviation,
and new possibilities for practical use of high power density superconducting electric
machines.

Sustainable Development Goals (SDGs) approved by the United Nations Summit
2015 target world-wide, sustainable co-existence of human lives and our
environment coming from effective creation and consumption of energy. About half
of all electric power is consumed by electric motors. Because of this large electric
power requirement, even a 0.1-0.2 % global enhancement of efficiency contributes
to a tremendous aggregate energy saving and CO2 emission reduction. One way to
design high efficiency motors is to adopt superconducting technology providing zero
electrical resistance. Thus, a world-wide competition of R&D for superconducting
motor/generator is under progress, and global cooperation will accelerate progress
of this challenging and beneficial technology towards a commercial reality.

 Superconducting bulk potentially provides a highly intensified magnetic field up
to more than 10 tesla with smaller dimensions than conventional superconducting
coils produced by using the same superconductors as in bulk. This enables
downsizing the electric machines and transportation or other application system.
On the other hand, it has been difficult to manufacture a high-quality and a large
size of superconducting bulk products. Therefore, until now, application of bulk
superconductors has been assumed to be adaptable for small scale machine but
impractical for large scale magnets and electric machines like ship propulsion motors
or wind power generators. The new prototype machine includes the following
innovative aspects to overcome the previous obstacles.

 ① A rotor field pole assembly for the motor was composed by combining an
   array of high-quality superconducting bulks (QMGs), and this field pole
   unit is treated as a standard bulk magnet for a variety of magnetization.
   (Patent pending)
 ② A field pole unit can be magnetized by using a new magnetization
   technique, which enables magnetization of a pole inside the machine with
  ease.
   (Patent pending)
 ③ Standardized and scalable field pole modules can be used for a large
   range of electric machines. This provides versatility for many machine
   applications of bulk HTS QMGs.

 We have successfully operated a series of rotating tests under a variety of loads.
Despite academic concerns of magnetic field degradation in machine applications
under varied external magnetic fields, the measurements of the bulk HTS field pole
have demonstrated an undiminished magnetic field surviving under full load
conditions with different rotating frequencies up to 190 rpm. The prototype machine
exhibited more than 700 hours including 360 hours under loads, together with up
to 537 Nm torque which is a world record by bulk HTS field poles in a prototype
propulsion motor.

Thermal stability and no demagnetization were detected together with a precision
of ±2 ℃ in temperature and 1 % of magnetic pole field.
 This prototype clearly proves the possibility of a large scale, high-efficiency motor
or generator using high-temperature superconducting (HTS) bulk materials.
 Applied HTS bulk for propulsion motors, wind-power generators, tidal/wave power
generators, and aeropropulsion motors/generators could be developed to overcome
the next generation electric transportation and energy challenges in the forthcoming
SDGs periods.


20180803.jpg

*Material product of crystal block of superconductor achieved by crystal growth from liquid phase
by using a seed crystal, similar to the semiconductor Si growth process. In appearance, QMG
seems to be another permanent magnet (PM) of metal alloys, but more than ten times magnetic
field is provided after proper magnetization process below superconducting critical temperature
(photograph, see below)

About high quality, high-temperature superconducting (HTS) bulks, QMG

-->NSSMC technical report 'New material special issue'
( http://www.nssmc.com/tech/report/nssmc/no407.html )

Development of New Reinforcement Method and 10 T Magnetization of QMG
Magnet (Mitsuru Morita, Eiichi Teshima, Shinya Nariki) (PDF 5.47 MB)

-National University Corporation, Tokyo University of Marine Science and
Technology (TUMSAT), Public Relations Office,
Phone:+81-3-5463-0355,
Email: izumi@kaiyodai.ac.jp

-ABB Corporate Research、940 Main Campus Drive、27606, Raleigh, North Carolina,
UNITED STATES、Phone: +1 919 829 4407,
Email: steven.englebretson@us.abb.com

- Nippon Steel & Sumitomo Metal Corporation: Public Relations Center,
Phone: +81-3-6867-2977

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