Magnetizing Technique for Permanent Magnets in IPM Motor Rotors Using HTS Bulk Magnet

A unique activation technique for permanent Nd-Fe-B magnets which were embedded in the rotors of interior permanent magnet (IPM) motors has been developed as a magnetizing tool with use of high temperature superconducting (HTS) bulk magnet. The experimental and numerical simulation studies were conducted to evaluate the magnetic field-trapping performances of the rotor of air-conditioner compressor in the hybrid-type automobiles. The sample rotor containing six demagnetized permanent magnet plates were exposed in the intense static magnetic fields above the magnetic pole which contained the bulk magnet generating over 4 T. As a result, the sample magnets were perfectly magnetized in the static magnetic field. The precise simulation on the flux distribution in the rotor clarified that it is important to make the flux direction in the rotor core and the easy magnetization axis of PM identical. We convinced this activation technique should enable us to promote the degrees of freedom of motor designing and its processing.