The Nagoya Institute of Technology developed a hybrid field motor that can be used for vehicles.
A hybrid field motor generates a magnetic force by synchronizing a permanent magnet and an electric magnet.
The hybrid field motor prototyped by the university uses half the amount of rare-earth magnet compared with a synchronous motor equipped in a commercially-available hybrid-electric vehicle (HEV) even though it has the same size, the same maximum output of 123kW and the same output density as the synchronous motor.
The output density of the hybrid field motor is 3.4kW/kg, which is not particularly high for a synchronous motor but the world's highest level for a hybrid field motor.
To make the synchronization of the permanent magnet and the electric magnet effective, the university employed an SMC (soft magnetic composites) core. An SMC core is made by applying insulating coating to the surface of magnetic particles such as iron particles in addition to compression molding and heat treatment.
With this method, it is possible to shape and mass-produce magnetic parts that have complex three-dimensional structures at a low cost.
Rare-earth magnets are used for the synchronous motors for HEVs. But 90% of the rare-earth materials are imported from China (at least in the case of Japan), and their prices are doubling or even tripling due to growth in demand.