Magnetic Interaction Effect on Stall Torque of IPM-type Magnetic-Geared Generator

Magnetic-geared generators (MGGs) are expected to be applied to wind-power generation because of maintenance-free, high torque density and efficiency. Among them, an interior permanent magnet (IPM)-type MGG has superior characteristics compared with a surface permanent magnet (SPM)-type MGG. The stall torque of the IPM-type changes with the current phase angle because of magnetic interaction, while the SPM-type keeps constant. This paper investigates the effect of magnetic interaction on the stall torque of IPM-type MMG using both a three-dimensional finite element method (3D-FEM) and experiments. In addition, since the stall torque can be improved by magnetic interaction, a novel high-speed rotor structure is proposed to maximize the effects of magnetic interaction to achieve the same stall torque while using fewer permanent magnets. The validity of the proposed new high-speed rotor structure is proved by using 3D-FEM.