Patent ID: 7102319

Claim:
A rotation control method of a synchronous motor, said motor comprising: a stator having AC windings thereround; and a rotor, being mounted within said stator, rotatably, wherein on an each surface, opposing to said rotor, of poles building up said stator, are formed plural numbers of teeth portions, and on a surface of said rotor, being made of permanent magnet, opposing to said poles of said stator, are also formed plural numbers of teeth portions, with a width being nearly equal to that of said teeth portion in a circumference direction thereof, and further AC voltages having a predetermined voltage-frequency characteristic is supplied to AC windings wound around the poles of said stator, and the AC voltages supplied from said inverter is so determined in the voltage-frequency characteristic thereof, at least within a part of frequency band equal or less than a predetermined rated frequency, a pull-out torque of said synchronous motor is equal to or greater that a rated pull-out torque at said predetermined rated frequency.