DE2518786B2 - Six-phase stator winding of an electrical machine - Google Patents

Description

The invention relates to a six-phase stator winding an electrical machine made up of two three-phase windings that are electrically offset against each other consists.

The development of energy technology leads to a steady increase in the individual output of turbo generators. The application of the Six-phase stator windings. The six-phase windings increase the machine utilization as a result their better winding factor. They also have a number of other advantages, e.g. B. decrease the additional losses of machines.

For turbo-generators, six-phase windings are used from a power of 1200 MW expedient.

The well-known six-phase stator windings of turbo generators (DE-OS 15 38 969) are through formed two electrically shifted three-phase windings. Usually this is Shift 30 ° el. In this case, the six-phase EMF applied to the machine terminals easily converted into a three-phase emf by means of a transformer, using a low voltage winding of the transformer in star and the other in delta and switches each of these windings connects to the corresponding three-phase winding of the generator. The high voltage winding of the The transformer is connected in star.

One shortcoming of the six-phase windings mentioned is that they are opposite to the three-phase winding has a higher tension between the winding bars in the end winding.

As the output of turbo generators increases, so does the voltage on the stator winding at. Power turbo-generators for voltages of 22 kV and above are currently being used developed. One of the most important problems with such a voltage increase is the corona discharge in the End winding of the stator winding.

Two-layer three-phase windings are usually used for turbo-generators, in which the highest voltage between the adjacent winding bars in the end winding at the joints of the Phase zones arise in which the strongest corona discharge appears.

With star-connected windings, this voltage is 1.73 times the phase voltage.

In the six-phase windings mentioned with a shift of three-phase windings by 30 ° el. the voltage between the winding bars at the joints of the phase zones reaches a value the 1.93 times as large as the phase voltage, i.e. 11.5% greater than with three-phase windings with the same phase voltage.

-. The invention is based on the object of creating a six-phase winding with a lower maximum voltage between the winding bars in the end winding.
In the case of a winding, this task is the one at the beginning

in the named, e.g. known from DE-OS 15 38 969, Type solved according to the invention in that the phases of the same name of the two three-phase windings in are wound in opposite directions, so that a three-phase winding from left to right iort-

i ") striding and the other from right to left is progressively inserted.

By designing the winding in this way, the maximum voltage occurring at the joints between the phase zones is reduced and is approximately equal to the phase voltage. A corona discharge is practically impossible even at a high nominal voltage. This makes it possible to further increase the nominal voltage of the machines.
An embodiment of the invention in the form of a

r> two-layer six-phase winding for 36 slots is explained in more detail below with reference to the drawing explained.

F i g. 1 shows a basic circuit diagram of the six-phase winding embodied according to the invention, and

K> Fi g. 2 shows a vector diagram of the groove emf in FIG the in F i g. 1 illustrated six-phase winding.

In Fig. 1 shows a two-layer six-phase stator winding of a turbo-generator, which from FIG two threephase shifted by 30 ° el.

There are no developments. The reference numerals 1 to 36 denote the slots in the stator. In the circuit diagram, the upper winding ends are shown in solid lines and the lower winding bars are shown in dashed lines. The first three-phase winding is drawn in thick lines and the second three-phase winding is drawn in thin lines. The connections of the three-phase windings are brought out on different sides of the stator. The beginning of the phase of the first three-phase winding are denoted by Α}, Β}, Ci and the phase ends A \, Bi, C _2.

4> Correspondingly, the phase beginnings of the second three-phase winding have the designations / I ₂ ", O ₂ ", C ₂ "and the phase ends the designations A {\ B '\ C".

Each winding phase occupies two phase zones on the circumference, i. that is, the whole circumference is in twelve

μ phase zones divided. In the present exemplary embodiment, each phase zone comprises three grooves.

For example, the first zone of winding phase A in the upper winding layer has slots 1, 2, 3 and the second zone of phase A has slots 19, 20, 21

" a.

The coil groups of a phase, which comprise different phase zones, are connected in parallel (a series connection is also possible).
In Fig. 1 is the shift of the A ¹ and A "phases

of the two three-phase windings at 30 ° el.

The turns belonging to the first zone of phase A ¹ are connected according to the slot sequence 1-16-2-17-3-18 , that is, the winding proceeds to the right. The next zone takes phase A ^{11 of} the second

b5 three phase winding a. When circulating this phase, according to FIG. 1 the grooves 21-6-20-5-19-4, d. h “the winding proceeds to the left.

So the first three phase winding is from the left to the left

advancing to the right and the second three-phase winding in reverse, d. H. according to the drawing inserted progressively from right to left.

Thus, the phases of the same name in the three-phase windings are wound in the opposite direction. In In this case the tension between the bars is at the junction of the phase zones in the end winding approximately equal to the phase voltage. This is illustrated by FIG. 2 illustrates.

In Figure 2, the designations correspond to tier Vectors of the slot EMF in the six-phase winding the designations of the stator slots in Fig. 1. The Upper rod emf vectors are in thick lines and lower rod emf vectors are in thin lines Lines shown.

The EMF of a zone of phase A ^{1 of} the first three-phase system is equal to the EMF vector sum of the slots 1-16-2-17-3-18 in the corresponding order. The EMF vector of slot 1 relates to the beginning of the phase and the EMK VeV.tor of slot 18 to the end of the phase. This means that the rod lying in the groove 1 is at phase voltage with respect to earth and the voltage on the rod lying in the groove 18 is zero with respect to earth.

> We now consider the voltage at the joint the phase zones, e.g. B. between the upper rods which lie in the groove 1 and in the groove 36.

The upper rod lying in the slot 1 belongs to phase A ^{1 of} the first three-phase winding, and that in the

H) Groove 36 lying upper rod belongs to phase ß ^{11 of} the second three-phase winding. As can be seen from Fig. 2, the voltage between these bars is only half the winding voltage higher than the phase voltage. The tension between the

i ") others lying at the buttocks of the phase zones Bars does not rise above this value either. Thus, the invention ensures the reduction in the Six-phase winding at the joints of the phase zones occurring maximum voltage to a value that corresponds approximately to the phase voltage.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Six-phase stator winding of an electrical machine, which consists of two electrically against each other shifted three-phase windings consists, d a characterized by the fact that the same name Phases of the two three-phase windings are wound in opposite directions, so that one three-phase winding proceeding from left to right and the other from right to left is progressively inserted.