JPS5946409B2 - rectifier transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a DC winding of a double star-connected rectifier transformer with an interphase reactor.

In a double star-connected rectifier circuit with an interphase reactor, the two three-phase groups operate like independent three-phase rectifiers, 2π, and each anode operates for a period of (/+u), depending on the leakage reactance of each group of the transformer. An overlap commutation of the anode current takes place.

Here, u indicates the overlapping angle. Therefore, if the leakage reactance of each group is different, the anode current becomes unbalanced, causing problems such as direct current bias magnetization of the interphase reactor. Therefore, the DC winding of this type of transformer must be structured to minimize the difference in leakage reactance between the groups. FIGS. 1 and 2a show cross sections of concentrically arranged windings of a conventionally used double star-connected rectifier transformer.

1 is an iron core, 2 is an AC winding, 3a and 3b are windings of a first group of DC windings, and 4a and 4b are windings of a second group of DC windings.

The DC winding shown in FIG. 1 has a structure in which the windings 3a and 4a of each group are finely divided into disk shapes, arranged alternately, and connected in parallel.

The DC winding shown in FIG. 2a has a structure in which two groups of windings 3b and 4b are wound together into a cylindrical shape.

FIG. 2b is a front view showing the DC windings 3b and 4b of FIG. 2a. The structure described above has advantages and disadvantages depending on the capacity of the DC winding and the insulation level cooling method, and has the following characteristics. The structure shown in Figure 1 is often used for windings with large currents and low voltages, but not only does it require a lot of effort to connect externally to the windings, but it is also common to use AC windings 2 due to the external connections of DC windings. Since it is installed on the inside, it is difficult to install a voltage adjustment tap on the AC side, and furthermore, the DC winding has a V
Because the winding capacity is twice as large, there is a disadvantage that the winding material is more bulky than when the DC winding is placed inside. The second structure is a structure used for windings of medium and small currents, but since the two groups of windings 3b and 4b of the DC winding are adjacent to each other, insulation treatment between the two groups of windings 3b and 4b is required. This method has the disadvantage of requiring a solid insulating material, requiring a lot of time and effort for insulation treatment, and requiring a large amount of insulation material.

On the other hand, as a winding structure in which the secondary windings of a transformer are divided into two groups, the first group and the second group of windings 3c and 4c as shown in FIG.
There is one in which the layer is divided into multiple layers and these layers are arranged concentrically. This structure simplifies the processing of the windings, but for the reasons explained below, the windings 3c, 4cC7 of the first group and the second group
) Due to the large difference in leakage reactance, it cannot be applied to the windings of a double star-connected rectifier transformer. In other words, the leakage reactance of the concentrically arranged transformer windings is expressed by the following equation. X■? =X1+X.

......(1). Figure 3a shows the ampere turns (n-1)k of each layer of the two groups 3c and 4c of the DC winding.
Fig. 3b shows a magnetomotive force distribution diagram of the AC winding 2 and the first group 3c of DC windings, and Fig. 3c shows the magnetomotive force distribution diagram of the AC winding 2 and the DC winding. A magnetomotive force distribution diagram with the second group 4c is shown. From equations (1), (2), and (3), the leakage reactance is proportional to the leakage magnetic flux, and the magnetic flux distribution inside the windings and the air gap between the windings is similar to the magnetomotive force distribution. This is because the leakage reactances of the two groups of windings 3c and 4c in the structure are not equal. The present invention aims to provide a rectifier transformer that improves the drawbacks of conventional DC windings by manipulating the magnetomotive force distribution of the DC windings, and will be explained below with reference to the drawings.

FIG. 4 shows one embodiment of the present invention, and FIG. Windings 13, 1 in different groups of layers
4 shows a winding structure in which four winding layers are arranged concentrically so as to face each other, and the width Gk of the gap in each winding layer is different.

Figure 4b is a magnetomotive force distribution diagram between the AC winding 2 and the winding 13 of the first group of DC windings, and Figure 4c is a diagram of the magnetomotive force distribution between the AC winding 2 and the winding 14 of the second group of DC windings. A magnetic force distribution diagram is shown. (1), (2),
(3), in the case of concentrically arranged windings, the average radius Rk' of each winding layer and the average radius Rk of the air gap are different, so the magnetomotive force distribution is adjusted according to these values.

That is, by adjusting the value of Gk, the second group of windings 13, 1
The leakage reactances of 4 can be made equal. In this way, when two groups of DC windings are each divided into a plurality of cylindrical winding layers and these are arranged concentrically, the two groups can be divided by changing the width of the gap between each winding layer. According to the present invention, which is configured to equalize the leakage reactance of the windings, the insulation treatment of the DC winding becomes simple, and the winding can be easily machined with fewer connection points.

Although the explanation has been based on the case where the DC winding is located on the inside, it goes without saying that the present invention can also be applied to a case where the DC winding is located on the outside.

[Brief explanation of the drawing]

Figures 1 and 2a are cross-sectional views showing conventional windings, Figure 2b
is a front view showing the DC winding in Fig. 2a, Fig. 3a is a cross-sectional view of the winding without considering the magnetomotive force distribution, Fig. 3b is a magnetomotive force distribution diagram of the first group of windings, Figure c is a magnetomotive force distribution diagram of the second group of windings, Figure 4a is a sectional view of the winding according to an embodiment of the present invention, Figure 4b is a magnetomotive force distribution diagram of the first group of windings, FIG. 4c is a magnetomotive force distribution diagram of the second group of windings. 1...Iron core, 2...AC winding, 13.
...First group of DC windings, 14... Second group of DC windings.

Claims (1)

[Claims] 1 A double star-connected DC winding with an interphase reactor consisting of two groups of windings, each group of windings having a plurality of cylindrical winding layers arranged concentrically. In,
A transformer for a rectifier, characterized in that the width of the gap in each winding layer of the two groups of windings is made different to equalize the leakage reactance of the two groups of windings.