PERMANENT MAGNET MOTOR AND ELEVATOR

摘要

PROBLEM TO BE SOLVED: To reduce vibration and noise by reducing cogging torque and torque ripple. SOLUTION: A winch 23 has a rotor core 33 which has permanent magnets 37 built in for forming magnet poles inside. The inner peripheral surface of each magnetic pole of the rotor core 33 is convexly formed to make an air gap with a stator core 26 which is smaller at the center and larger at both edges of the magnetic pole in the circumferential direction. Specifically the inner peripheral surface of each magnetic pole has a plane surface 33a at the center and circular surfaces 33b at both edges in the circumferential direction. As a result distribution of magnetic flux between the rotor core 33 and the stator core 26 highly approximates a sinusoidal waveform and the cogging torque is reduced.