The rotor 306 is provided with: a rotor core 304; permanent magnets 305 that are attached to an outer periphery of the rotor core 304 in order to constitute a multipolar magnetic field; and the rotating shaft 307, which is provided in a state of passing through an axial center part of the rotor core 304. The rotor 306 is arranged on an inner side of the stator 303 in a state of sharing a same center axis as the stator. The rotating shaft 307 is supported, due being closely fitted with inner races of the first bearing 6A and the second bearing 6B, so as to be capable of rotating relative to the motor housing 2.

In the example shown in the drawings, in order to improve characteristics of the motor (e.g., to reduce torque ripple), the rotor 306 is configured from two divided rotors 306A and 306B that are arranged so as to be lined up in an axial direction in a state in which phases of the magnetic fields of the magnets are shifted. However, the present invention is not limited to cases where such a rotor is used.

The electric motor 1 in the present embodiment is a brushless DC motor in which the rotor 306 is caused to rotate by controlling excitation of the stator coil in accordance with a rotation-angle position of the rotor 306. However, it is possible to implement the present invention irrespective of what type of motor is used.

In the present embodiment, the stator coil 302 comprises two systems, i.e., coils A1 and A2, as shown in FIG. 16. The first-system coil A1 comprises three-phase (U to W) coils Lu1 to Lw1, and the second-system coil A2 comprises three-phase (U to W) coils Lu2 to Lw2.