Yaskawa Electric Corp developed a motor that is for driving electric vehicles (EVs) and does not use neodymium.
The company ensured a performance and dimensions equivalent to those of a motor using neodymium by optimizing the shapes and positions of magnet, motor core, etc.
The new motor has an IPM (interior permanent magnet) structure, in which a ferrite magnet is embedded in a rotor. Its torque characteristics were enhanced by optimizing the shapes of the magnet, core, etc. Also, its low-temperature demagnetizing factor was improved to eliminate the need for neodymium.
Furthermore, Yaskawa realized the dimensions equivalent to those of a motor using a neodymium magnet by employing a rectangular wire whose cross-section has a rectangular shape to increase the density of stator's winding wire and optimizing the magnetic circuit of the rotor.
With the employment of the rectangular wire, the ratio of conductive materials in the stator's winding wire increased by about 30%. Also, it became easier to automate production.
The prices of rare-earth materials including neodymium sharply fluctuate because many of them are eccentrically located, making it difficult to stably obtain them. Therefore, Yaskawa decided to develop an EV motor using a ferrite magnet, which has a lower price.
As for the specifications of the motor, it has a maximum rotation speed of 12,000rpm, continuous output of 45kW, maximum output of 80kW and maximum torque of 200N·m. It measures 250 (W) x 194 (H) x 355mm (D) and weighs about 60kg.
Yaskawa will show a panel explaining the motor at the 4th EV & HEV Drive System Technology Expo, which runs from Jan 16 to 18, 2013, in Tokyo.