Experimental studies on drive performances of less rare-earth PM hybrid excitation motor

This paper presents feasibility studies on hybrid excitation motor (HEM) as a candidate of less rare earth permanent magnet and high power density machine for hybrid electric vehicle drives. The construction, the basic working principle focusing on variable field control capability and the design concept of HEM are overviewed. After making the design restrictions and specifications clear, the drive performances of HEM designed are evaluated based on 3D-FEA. As a result, the proposed motor makes possible to reduce the volume of rare permanent magnet by approximately half of that used in existing interior permanent magnet synchronous motor for LEXUS RX400h while keeping the power density intact. With comparisons between the measured and the computed drive performances of the trial manufacturing of the downsized motor, it is verified that HEM becomes an attractive candidate as a less-rare-earth permanent magnet and high power density motor for HEV drives.