In Embodiment 4 above, a 10-pole 12-slot inner-rotor three-phase motor is used, but the motor is not limited to a 10-pole 12-slot inner-rotor three-phase motor, provided that it is an inner-rotor three-phase motor in which the number of poles is 10N and the number of slots is 12N, or the number of poles is 14N and the number of slots is 12N (where N is a positive integer).