October 2, 2020
Sumitomo Electric Industries, Ltd.
*This press release was originally published in Japanese on September 16, 2020

Sumitomo Electric Commences Mass Production of Powder Magnetic
Cores for Axial Gap Motors to Create Thin and High-Performance Motors
Sumitomo Electric Industries, Ltd. has developed a powder magnetic core foraxial gap motors, which are advantageous for creating thin and highperformance motors (in terms of output and efficiency). The Company started
mass production and delivery of the product in August 2020.
With recent growing demand for light and high-performance motors, axial gap motors*1are attracting more attentions due to their light weight, low thickness , and high power
density, which have been achieved by adapting completely different structure fromconventional motors (radial gap motors) . In order to produce axial gap motors, highquality magnetic cores*2 that suit their three-dimensional magnetic circuits areindispensable.
By utilizing our unique powder metallurgy technology, Sumitomo Electric hasdeveloped a powder magnetic core that helps to realize high-performance axial gap
motors. In addition, the Company has newly developed an insulation coating
technology to ensure the dielectric strength between the powder magnetic core and thecopper winding, and has started the mass production and delivery of the insulationcoated powder magnetic core as an ideal component for axial gap motors.
In the future, Sumitomo Electric will continue to develop the market for powder
magnetic cores for axial gap motors and contribute to the development of higher
performance axial gap motors and equipment.
■ Features of the Powder Magnetic Core for Axial Gap Motors
A powder magnetic core is formed by die-pressing soft magnetic iron powder into athree-dimensional shape. Compared to magnetic cores made of electrical steel sheets
used in conventional radial gap motors, it has great flexibility in terms of shape designand superior high-frequency characteristics, and has been put into practical use invarious fields, such as automobile applications.

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When using a powder magnetic core for a motor, it is usually required to provide an
additional component to ensure the dielectric strength between the magnetic core andthe copper winding. However, our unique insulation coating technologyhas made it
possible to wind copper wire directly around the powder magnetic core and thereby
reduce costs for additional components and assembly. This feature can increase thewinding space, which contributes to the development of more compact and efficient
motors.
In addition, the Company provides assistance for three-dimensional electromagnetic
field analysis of axial gap motors based on motor specifications provided by customers

so that they can realize the advantages of the powder magnetic core for axial gap
motors.
(Left) Insulation-coated powder magnetic core for axial gap motors (mass producedproduct)(Right) Powder magnetic cores for axial gap motors (prototype)*

1: Axial gap motor:

Compared to conventional radial gap motors, axial gap motors are superior in power
density and efficiency in the category of thin motors.
As shown in the table below, lighter weight and lower thickness can beachieved with performance kept at the same level as a conventional radial gap motor.

2/3Radial gap motor

Axial gap motor(conventional)
Structure

Copper winding(schematicdiagram)

Electricalsteel sheet

ShortPowder magnetic core

83.0

35.0 (-58%)

Weight (kg)3.2

1.6 (-50%)

Torque (N  m)

0.65

0.65 (--)

Maximum

90.6

90.9 (+0.3%)

axial
length (mm)efficiency (%)
Table. Electromagnetic field analysisfor an axial gap motor* This analysis is an example and does not show the relationship between all radial gap
motors and axial gap motors.
* Total length and weight are analysis values including the housing.
* The schematic diagrams are images with partial cross-sectional views. They may differ
from actual dimensions and structures.
*2: Magnetic core:
A magnetic core is a component around which copper wire is wound and used as amagnetic circuit to amplify the magnetic force. It is also called an iron core or core.

■ ReferencePowder magnetic core (FMCM series)
https://global-sei.com/pmp/index_eng.html

Development of powder magnetic core for axial gap motors
https://global-sei.com/technology/tr/bn86/pdf/86-21.pdf

Sumitomo Electric's Website：https://sumitomoelectric.com/
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