Study on Higher Output Power Spoke-Type IPM Motor with Flask-Shaped Magnet

This study presents a novel rotor structure for spoke-type IPM motors. In the proposed structure, the magnets are molded in a flask shape and arranged radially in the rotor, similar to the conventional spoke-type IPM motors. Owing to this structure, the magnets are jammed onto the rotor core and held against centrifugal forces. Therefore, the bridge that holds the magnets can be eliminated, which is a leakage flux path in conventional structures, and the rotor flux can be increased. The advantage of the proposed structure is the reduction of leakage flux, which enables a higher torque than conventional spoke-type IPM motors with the same number of magnets. To validate its effectiveness, numerical verification using the finite element method was conducted to evaluate its magnetic and strength characteristics. Moreover, the obtained results were compared with those obtained using conventional motors. From the numerical results, it can be confirmed that the maximum torque and output power of the proposed motor are higher than those of a conventional motor.