Technology news: April 2012
High-efficiency synchronous motor avoids rare earths
Hitachi has announced the development of a high-efficiency, 11kW permanent magnet synchronous motor that does not contain any rare-earth materials. The motor, with a claimed efficiency of 93%, is said to deliver IE4 performance from a smaller frame size than a conventional motos.
The double-rotor, axial-gap motor incorporates a laminated stator core based on an amorphous iron material with losses claimed to be about 10% of those of conventional steel laminations. The amorphous material, formed by cooling the molten metal rapidly, avoids the crystalline structure of conventional steels, thus exhibiting lower losses.
The motor’s double-rotor construction is said to enhance the magnetic energy of the ferrite permanent magnets. It has been designed to be rugged to withstand the high centrifugal forces and large torques encountered in the motor. Hitachi used 3D magnetic field analysis software to study the characteristics of iron core laminations and to validate the efficiency of the design.
The new motor is aimed at applications such as fan and pump drives. It is expected to go on sale during 2014.
The motor is based on work dating back to 2008 when Hitachi developed a 150W prototype axial-gap motor with a low-loss amorphous metal core.
Other motor manufacturers, including Nidec and Mitsubishi, are also working on motor technologies that avoid the need for rare-earth materials which have risen steeply in price in recent years as their main producer, China, has restricted supplies.