Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1991-12-30
1993-03-23
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 67R, 310203, 310214, 310216, 310259, H02K 112
Patent
active
051967510
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a large-diameter a.c. motor with a stator having joints. The stator carries a stator coil formed of windings which are arranged in two layers and disposed in grooves. The stator also has switching connections extending over its circumference, in which the stator coil is divided into several zones of closed windings. These zones correspond to the number of joints. The closed windings lie only in the groves between the joints.
Such divisible stators of large-circumference a.c. motors, especially of a synchronous design, are known. Due of the special structure of the stator coils described in DE-C-761 310, to simplify assembly of the a.c. motor at the installation site, the joints are not covered by windings. Only the switching connections are passed over the joint, and can be connected with each other at the joint such that they can be released, in known manner. In an a.c. motor with such a construction, each of the grooves of the stator adjacent to the joint is only occupied with one winding layer.
The armature reaction changes at the one-layer arrangement of the winding sides in the grooves adjacent to the joint. The present invention seeks to reduce the resulting disadvantages in the operation of such a machine.
SUMMARY OF THE INVENTION
To accomplish this task, according to the present invention, in an a.c. motor of the type described, initially the air gap is larger in the grooves adjacent to the joint. The closed windings have only one winding side. As a result, the lack of armature reaction in this area is compensated, at least in part. In particular, the occurrence of force waves of various magnitudes can be reduced at rated current operation.
The armature reaction changes at the one-layer arrangement of the winding sides in the grooves adjacent to the joint. It is desirable that the air gap is larger at the area where the grooves adjacent to the joint have only one winding side than at the area where the grooves have a two-layer arrangement of winding sides. As a result, the lack of armature reaction in this area is compensated, at least in part. In particular, the occurrence of force waves of various magnitudes can be reduced at rated current operation.
The enlargement of the air gap in the vicinity of the joint can be constant or can increase, continuously or in steps, in the direction of the joint. Thus, certain force waves magnetically caused by the local, lack ,of armature reaction can be influenced in a predetermined manner.
Furthermore, it is especially advantageous to use such a stator coil which leaves the joints free, with a.c. motors supplied with current of variable frequency because the magnetic force effects can be minimized by means of the free selection of the pole pair number given for sizing of the machine.
It is furthermore advantageous to mechanically reinforce; the stator coils by means of filler pieces. Each of the stator grooves occupied by only one winding layer can be filled with such filler pieces.
Furthermore, it is especially advantageous to use a stator coil which leaves the joints free, with a.c. motors which are supplied with current of variable frequency because the magnetic force effects can be minimized by means of the free selection of the pole pair number given for sizing of the machine.
It is furthermore recommended to undertake mechanical reinforcement of the stator coils by means of filler pieces, with Which the stator grooves occupied by only one winding layer can be filled in each case.
In the following, the invention is explained in greater detail on the basis of the embodiment shown in FIGS. 1 and 2; however, the invention is not limited to this embodiment.
FIG. 1 shows a cut-out of the wiring diagram of the stator coil of an a.c. motor with joints.
FIG. 2 shows a part of a radial cross-section through the stator armature stampings and the rotor of this a.c. motor.
DETAILED DESCRIPTION
A large-diameter a.c. motor is structured as an external rotor motor and is operated at varying rpm's, by a
REFERENCES:
patent: 3221195 (1965-11-01), Hoffmann
patent: 3515919 (1970-06-01), Houtman
patent: 3888552 (1975-06-01), Wehde
patent: 4594523 (1986-06-01), Horita
patent: 4600864 (1986-07-01), Sato
Siemens Aktiengesellschaft
Skudy R.
LandOfFree
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