PURPOSE: To utilize energy of a permanent magnet at the side of a stator to the utmost and to improve efficiency, by a method wherein rotor coils are arranged respectively on inner and outer circumferences of the cylindrical permanent magnet at the side of the stator.
CONSTITUTION: A permanent magnet 3 is arranged so that a gap is provided between inner circumference of a center through hole of the cylindrical permanent magnet 3 and outer circumference of an inner yoke 4, and an inside coil 9 installed along the gap at side of a rotor 5 is rotatably arranged in the concentric circular form. The coil 9 is fixedly supported by a support body 7' installed on a rotary shaft 6 penetrating the inner yoke 2. A coil 8 installed between an outer yoke 1 and the outer circumference of the permanent magnet 3 is fixedly supported by a support body 7 installed on outer circumference of the support body 7'. The rotor 5 is constituted by these outer and inner coils 8, 9 and the rotary shaft 6.