| 摘要 |
A synchronous A.C. electrical motor comprising (A) a stator having a body of slotted, soft ferromagnetic, low eddy current loss material, the slots having A.C. power windings to produce a rotating magnetic field, an excitation coil energizable with single phase A.C. located in two adjacent slots with a pole piece between them, and feedback windings located in slots such that when A.C. potential therefrom is conveyed to the excitation coil the excitation A.C. is modified to a selected phase and magnitude to improve the "pull in" torque of the motor, a capacitor containing circuit connecting the feedback windings and the excitation coil, the body of ferromagnetic material having a circular cylindrical surface, and (B) a rotor having three major components electrically and magnetically associated, (1) first being an exterior layer of a low electrical conductivity magnetizable permanent magnetic material having an outside cylindrical surface complementary to that of the stator, (2) a high permeability, low eddy current component to which the first layer is attached, and (3) the third component being a supporting body of ferromagnetic material of high permeability and high electrical conductivity on which the second component and first layer are fixedly supported. The third component can be a solid ring of steel, for example, or it can be a laminated core containing shorted electrical conductors. In starting from standstill, the power windings are energized with A.C. power and this produces a circulating electrical current with the third component of the rotor which reacts to produce rotational torque. After the rotor reaches about 70 to 80% of synchronous speed, the excitation coil is energized and this will produce strong alternating magnetic flux in the pole piece which magnetizes the layer of the permanent magnetic material into a pattern of north and south magnetic poles in the proper phase with the rotating field of the stator so as to produce a powerful rotational torque that accelerates the rotor to a predetermined synchronous speed. |
