Sumitomo Electric develops powder magnetic core for thin and high-performance motors

October 2, 2020

Left: Insulation-coated powder magnetic core for axial gap motors (mass-produced product). Right: Powder magnetic cores for axial gap motors (prototype) (Courtesy Sumitomo Electric Industries, Ltd)

Sumitomo Electric Industries, Ltd., headquartered in Osaka, Japan, reports that it has developed a powder magnetic core for axial gap motors, said to be advantageous for creating thin and high-performance motors in terms of output and efficiency. The company states that it started mass production and delivery of the product in August 2020.

According to Sumitomo Electric, with the recent growth in demand for light and high-performance motors, axial gap motors are attracting more attention due to their light weight, low thickness, and high power density, achieved by adapting a different structure from conventional motors (radial gap motors).

In order to produce axial gap motors, high-quality magnetic cores that suit their three-dimensional magnetic circuits are requirede. Using its Powder Metallurgy technology, Sumitomo Electric has developed a powder magnetic core that helps to realise high-performance axial gap motors.

In addition, the company has developed a new insulation coating technology to ensure the dielectric strength between the powder magnetic core and the copper winding, and has started the mass production and delivery of the insulation-coated powder magnetic core as an ideal component for axial gap motors.

The table shows electromagnetic field analysis for an axial gap motor (Courtesy Sumitomo Electric Industries, Ltd)

Features of the powder magnetic core for axial gap motors

The powder magnetic core is formed by die-pressing soft-magnetic iron powder into a three-dimensional shape. Compared to the magnetic cores made of electrical steel sheets used in conventional radial gap motors, the PM route offers  great flexibility in terms of shape design and superior high-frequency characteristics, and has been put into practical use in various fields, such as automobile applications.

When using a powder magnetic core for a motor, an additional component must often be provided to ensure the dielectric strength between the magnetic core and the copper winding. However, the company states that its unique insulation coating technology has made it possible to wind copper wire directly around the powder magnetic core, and thereby reduce costs for additional components and assembly. This feature has also made it possible to expand the winding space, which contributes to the development of more compact and efficient motors.

In addition, Sumitomo Electric provides assistance for three-dimensional electromagnetic field analysis of axial gap motors based on motor specifications provided by customers so that they can realise the advantages of the powder magnetic core for axial gap motors.

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