| 摘要 |
PROBLEM TO BE SOLVED: To provide a composite three-phase stepping motor which has a function as a sensorless actuator, so as to obtain a state that a rotation irregularity is small even at a low speed and to provide a drive method for the motor. SOLUTION: A composite three-phase stepping motor is composed of a stator 1 constituted in such a way, that a permanent magnet 2 is sandwiched between two stators 1A, 1B provided with 6n pieces of stator magnetic poles A1 to C2 ', which protrude radially to the outside and which have NS pieces of pole teeth at respective tips and of a nearly ring-shaped magnetic body which is arranged, via an air gap, on the outer circumference of the 6n pieces of the stator magnetic poles A1 to C2 '. The stepping motor is provided with a rotor 4, which has Nr pieces of pole teeth on the inner circumferential side and with exciting windings 3 which are mounted on and attached to the respective stator magnetic poles over the two stators 1A, 1B. The exciting windings 3 uses 3n pieces of the stator magnetic poles as one set, and they are wound as a three-phase exciting winding which has two sets of the stator magnetic poles. Every angle which is formed between the 3n pieces of the magnetic poles is set at (60m/n), and every angle which is formed between two sets of the 3n pieces is set at (60m/n) -θS, whereθs represents a step angle, and (n) and (m) represent an integer of one or higher. |
