ROTATIONAL SPEED OF ROTARY ELECTRIC MACHINE AND ROTOR POSITION DETECTOR

PURPOSE: To assemble a detector while shortening the axial length as much as possible by disposing the first and second permanent magnets of the rotator of a rotor position sensor in the midway of interpole gap of a generator rotor for speed meter and in the midway of first magnet. CONSTITUTION: First permanent magnet 11 of the rotator 2 of a rotor position sensor is disposed in the center of interpole gap 13 of a permanent magnet 3 in the generator rotor 1 for speed meter such that two adjacent permanent magnets 11 have a polarity, on the facing side thereof, same as the polarity spreading across the interpole gap 13. Second permanent magnet 12 is disposed in the midway between two permanent magnets such that it has a polarity, on the side facing a generator rotor 1 for speed meter, opposite to the polarity of an axially adjacent generator rotor 1 for speed meter. According to the structure, a steep variation can be attained at the time of inductive polarity change of a rotor position sensor while accompanying an extremely small deviation of switching point in sensor element and a generator for speed meter and the rotor position sensor can be assembled while minimizing the axial length.