Success! Smart Collaboration [Examples of Collaboration]

Professor Satoshi Ogasawara & Mr. Kenichi Takezaki
Professor Satoshi Ogasawara & Mr. Kenichi Takezaki
Left: Mr. Kenichi Takezaki, Right: Professor Satoshi Ogasawara
Graduate School of Information Science and Technology, Division of Systems Science and Informatics, Research Group of Informatics for System Synthesis
Laboratory of Electric Energy Conversion
Professor
Satoshi Ogasawara
[Profile]
○Research fields: Electrical and electronic engineering (electrical power engineering, power conversion, electrical equipment)
○Research themes: Power electronics, motor control, EMI/EMC, energy conversion

■ Talking with

Dynax Corporation Development Division, Module Development Department
General manager
Kenichi Takezaki

Effective collaboration between university brains and corporate technical strength
Major contribution to the practical development of next-generation vehicle motors

Companies are watching NEDO results closely
Heading for shared research towards practical development and mass production

The Sapporo Motor Show 2014 took place in Sapporo Dome in February 2014. The Hokkaido SME Support, Japan Hokkaido Division booth exhibited a “In-wheel motor without rare earth materials” (fig.1) presented by Dynax Corporation. It is a drive motor for EV/HEVs (electric vehicles/ hybrid electric vehicles), jointly developed with the Graduate School of Information Science and Technology Laboratory of Electric Energy Conversion. Rare earths are the raw materials for the neodymium magnets commonly used in EV/HEV motors (commentary 1). In recent years, the world has depended on China for at least 90% of rare earth production, and problems such as rising prices and export controls have prompted a search for cheap motors which do not use rare earths (rare earth-less motors). In-wheel motors without rare earth materials are a technology that meets that this social need, and the motor attracted attention from many quarters by opening up the way to realizing that technology.

The base for rare earth-less motors was created by the “High-performance power storage system development project for next-generation vehicles” by the New Energy and Industrial Technology Development Organization (NEDO). The laboratory participated in the project from 2008 to 2011. The project developed a 50kW ferrite magnet motor for hybrid vehicles, which has a new structure and does not use rare earths (commentary 2, fig.2). Dynax, Japan’s largest domestic clutch plate manufacturer, focused on the results of this research and contacted the laboratory to suggest joint research. Together, they started research aiming for practical development and mass production of rare earth-less motors.

Mr. Takezaki, General manager of the Dynax Development Division Module Development Department says “We have been looking for new product development since around 2008, and we saw the potential of Hokkaido University’s rare earth-less motor. We have no experience of motor development, but we have mechanical design technology through clutch manufacturing, and we thought we could apply that”. Professor Ogasawara says “The NEDO project ended and we felt that we would like to make it useful to society, so the ability to do research closer to practical development was very attractive”.

A combination of motor efficiency and rotor strength,
through fusion between design and technical abilities

In the joint research, the laboratory handled the motor design, while Dynax was responsible for technical development for manufacturing and mass production. We made urban commuter cars, which are attracting attention as next-generation vehicles, the target type of EV/HEVs to use rare earth-less motors. “Urban commuters are a field with scope for venture companies and others to participate, not just automakers, and we through it would be better to aim for that kind of market”, says Mr. Takezaki. Urban commuters take an intermediate position between two wheels and four. They are compact, carrying one or two people, and they place the motors inside the wheels (“in-wheel”), in what would be dead space, to increase interior space. There are no other cases of combining rare earth-less and in-wheel motors, so the distinction from other companies was another advantage.
Professor Ogasawara says “Ferrite magnets are magnetically weaker than neodymium magnets, and it is difficult for them to produce torque from the motor alone, but we managed to get the necessary torque by using in-wheel motors combined with reduction gears. I think that was an extremely important result”.

The most difficult point was to achieve both motor efficiency and strength together. This motor differs from an ordinary cylindrical motor because it is an axial gap motor, in which the rotor and stator are arranged as disks facing each other. When rotated at high speed, strong centrifugal force acts on the edge of the rotor, and it was difficult to design it with sufficient strength to resist the force. Dynax reinforced the material with a coating of FRP (fiber-reinforced plastic) around the outside of the rotor. Mr. Takezaki says “The technology for coating with resin is also used in clutch manufacturing, so we were able to apply our expertise”. Clearing the rotor strength problem brought the motor a big step closer to completion.

Raise recognition and get on track for mass production
Expectations for collaboration between different fields

In February 2014, the development of the In-wheel motor without rare earth materials attained its initial goals and the joint research was completed. On the subject of mass production technology, Mr. Takezaki, feeling the challenge, says “there are many difficult aspects of mass production and cost, and we have not reached the level at which we can move into high-volume production, but I think we can clear these difficulties”. In future, we plan to exhibit extensively, at motor shows and elsewhere, to raise awareness of the motor.

Looking back on the joint research project, Professor Ogasawara says “In the laboratory I learned the perspective that is required, not just for building prototypes, but also for creating products. Attending destructive testing using equipment at Dynax was also a valuable experience”.
Mr. Takezaki, on the other hand, says “I don’t think we would have achieved this result without collaborating with Hokkaido University. I think it is difficult for companies to educate and retain the same kind of brains (human resources) that universities have, and cooperation with a university enables efficient development. It’s important for each side to bring in its own strong fields to build something better”.

The laboratory finds great significance in achieving joint development with different business types in fields other than motors. It sees potential for collaboration that transcends fields, and the frameworks of university and company, to achieve new breakthroughs. It is thinking of partnering with various machinery manufacturers in future.


Commentary 1 Neodymium magnets
Neodymium magnets are extraordinarily strong permanent magnets made from rare earths such as neodymium and dysprosium. Other than the motors of hybrid cars, they are used in many home electrical appliances, such as HDDs, cellular phones, and personal computers. In recent years, the world has depended on China for at least 90% of rare earth production, and problems such as rising prices and export controls have prompted a search for cheap motors which do not use rare earths (rare earth-less motors). Such motors would achieve stable supply and cost reductions.
Commentary 2 A 50kW ferrite magnet motor for hybrid vehicles, which has a new structure and does not use rare earths
Ferrite magnets are widely used as bar magnets, in small motors, and in magnetic products used in homes and offices. Their prices are around one tenth as high as those of neodymium magnets. They are seen as potential substitute materials for rare earths. The laboratory participated in the “High-performance power storage system development project for next-generation vehicles” which was set up in 2008 by the New Energy and Industrial Technology Development Organization (NEDO). It succeeded in developing a ferrite magnet motor which had the same volume as the drive motor of the 2003-model Prius and delivered the same output.

In-wheel motor without rare earth materials

Fig.1 Display of “In-wheel motor without rare earth materials” at the Sapporo Motor Show 2014

Fig.2 Ferrite magnet motor

Fig.2 Ferrite magnet motor