JPH03198309A - Transformer for cycloconverter - Google Patents

Abstract

PURPOSE:To decrease the phase difference between the positive impedance accompanying tap changeover and the negative group impedance as far as possible so as to check the output wave distortion of a converter by arranging the tap winding of primary winding between the primary main winding and the secondary winding positioned inside it. CONSTITUTION:The tap winding 26 of primary winding 23 is arranged between the primary winding 23 and the secondary winding 22 positioned inside it, that is, on the side of an inner main gap d1 where a gap is large originally. By doing it this way, the rate of the change of a leaked magnetic flux accompanying tap changeover becomes small, therefore the fluctuation of impedance also becomes small. That is, the phase difference of impedance between the positive group and the negative group accompanying tap changeover becomes small, and the distortion of output waveform does not become large. Moreover, each winding diameter of the primary winding and the second winding can be made small, and the entire constitution becomes small and light.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention provides a primary winding connected to an AC power source, and two windings connected to a positive group converter and a negative group converter of a cycloconverter, respectively. The present invention relates to a cycloconverter transformer comprising two secondary windings.

(Prior Art) An example of this type of cycloconverter transformer is shown in FIGS. 4 and 5. FIG. 4 is a diagram showing a schematic electrical configuration of a single phase component of the cycloconverter. In this FIG. 4, a transformer 1 for a cycloconverter has a primary winding 2 and two secondary windings 3.4. The primary winding 2 is connected to an AC power source, for example, a commercial three-phase AC power source 5.

One secondary winding 3 is connected to the positive group converter 7 of the cycloconverter 6, and the other secondary winding 4 is connected to the positive group converter 7 of the cycloconverter 6.
It is connected to the negative group converter 8 of the cycloconverter 6. The positive group converter 7 and the negative group converter 8 are connected in antiparallel as shown in the figure via the circulating current suppressing glue handles 9 and 10. Each converter 7.8 is formed by configuring, for example, a thyristor into a three-phase bridge control circuit. And each midpoint 9a of the reactors 9 and 10
and 10a are the output terminals of the cycloconverter 6. The single-phase alternating current output from this output terminal is configured such that its positive half wave is supplied by the positive group converter 7 and its negative half wave is supplied by the negative group converter 8.

Here, regarding the general winding arrangement of the transformer 1, the fifth
The details will be explained according to the figures. As shown in Fig. 5, the iron core 1
The one secondary winding 3 is wound around the one iron core leg 11a,
The primary winding 2 is wound around the outer periphery of this secondary winding 3, and the other secondary winding 114 is wound around the outer periphery of this primary winding 2. The primary winding 2 is composed of a tap winding 12 and a negative main winding 13 for coping with voltage fluctuations of the commercial three-phase AC power supply 5. The above-mentioned tap winding 12 is the negative main winding 1
3 and between the main winding 13 and the secondary winding 4.

In the above configuration, the positive half wave of the single-phase AC output from the output terminal of the cycloconverter 6 is the positive half wave of the positive group converter 7.
The negative half wave is supplied by the negative group converter 8. Therefore, in order to make the alternating current output waveform positive and negative symmetrical, it is necessary to make the positive group impedance and the negative group impedance equal. In this case, both secondary windings 3, 4
Since the capacitance and voltage are the same, the winding structure such as the conductor size and layer structure can be made the same. On the other hand, the distance between the inner circumferential surface of the primary winding 2 and the outer circumferential surface of the secondary winding 3 (hereinafter referred to as the inner main gap) and the outer circumferential surface of the primary winding 2 (in this case, the outer circumferential surface of the tap winding 12) If the distance between the inner peripheral surface of the secondary winding 4 (hereinafter referred to as the outer main gap) is made equal, and the distribution of leakage flux that affects the positive group impedance and the negative group impedance is made equal, the secondary Since the winding diameter of the winding 4 is larger than that of the secondary winding 3, the negative group impedance becomes larger than the positive group impedance. Therefore, by making the inner main gap larger than the outer main gap, increasing the leakage flux on the inner main gap side, and increasing the positive group impedance, the values of the positive group impedance and the negative group impedance are made equal. ing.

(Problem to be Solved by the Invention) Now, in the conventional configuration described above, how does each of the positive group impedance and the negative group impedance change depending on whether the tap winding 12 of the primary winding 2 is energized or not energized? Let's consider the impact.

In the above configuration, the secondary winding 3 is energized with a positive half wave, the secondary winding 4 is energized with a negative half wave, and the primary winding 2 is energized with a full wave. In this case, the distribution of leakage flux that affects the positive group impedance and negative group impedance is
The result will be as shown in the figure.

In FIG. 6, the leakage flux distribution when the entire tap winding 12 is energized, that is, at the highest tap, is shown by a solid line, and the leakage flux distribution when the entire tap winding 12 is not energized, that is, at the lowest tap, is shown by a dashed line. show.

Furthermore, in order to facilitate comparison of the leakage flux distributions for the positive group impedance and the negative group impedance, the inner main gap and the outer main gap are set to be equal.

As is clear from FIG. 6, as the taps are sequentially switched from the highest tap to the lowest tap, the leakage flux with respect to the positive group impedance decreases, so the positive group impedance becomes smaller. On the other hand, since the leakage flux for the negative group impedance increases as the taps are sequentially switched, the negative group impedance becomes larger. Therefore, as the taps are changed, the positive group impedance and the negative group impedance become largely different, resulting in a problem that the distortion of the output waveform of the cycloconverter 6 increases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a transformer for a cycloconverter that can minimize the difference between the positive group impedance and the negative group impedance caused by tap switching, and can prevent distortion of the output waveform of the cycloconverter as much as possible. is to provide.

[Structure of the Invention] (Means for Solving the Problems) A transformer for a cycloconverter of the present invention includes a primary winding that is connected to an AC power source and is made up of a main winding and a tap winding. In a device equipped with two secondary windings provided inside and outside the wire and respectively connected to a positive group converter and a negative group converter of the cycloconverter, the tap winding of the primary winding is connected to the main winding of the cycloconverter. It is characterized by the fact that it is placed between the secondary winding and the secondary winding located inside it.

(Function) In order to equalize the positive group impedance and the negative group impedance, the inner main gap is originally made larger than the outer main gap. In such an arrangement, in the conventional configuration, the tap winding of the primary winding is arranged between the negative main winding and the secondary winding located outside it, that is, on the outside main gap side. ing. On the other hand, according to the above means,
The tap winding of the primary winding is arranged between the negative main winding and the secondary winding located inside thereof, that is, on the inner main gap side. Therefore, since tap windings with the same number of turns are originally placed on the wide side of the gap, the rate of change in leakage magnetic flux due to tap switching is reduced compared to the conventional case where tap windings are placed on the narrow side of the gap. becomes smaller. Therefore,
゛The fluctuation of impedance is also reduced. As a result, the difference between the positive group impedance and the negative group impedance due to tap switching can be made smaller than in the past.

(Example) Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 and 2.

First, in FIG. 1, one secondary winding 22 is wound around the core leg 21a of the iron core 21, a primary winding 23 is wound around the outer periphery of this secondary winding 22, and furthermore, this primary winding 23 is wound around the outer periphery of this secondary winding 22. The other secondary winding 24 is wound around the outer periphery of the secondary winding 24 . This results in
Two secondary windings 22 and 24 are provided inside and outside the primary winding 23.

In this case, the inner secondary winding 22 is connected to a positive group converter of a cycloconverter (not shown), and the outer secondary winding 24 is connected to a negative group converter of the cycloconverter. The primary winding 23 includes a negative main winding 25 and a tap winding 26, and is connected to a commercial three-phase AC power source (not shown). By switching the tap of the tap winding 26 and changing the number of turns of the primary winding 23, it is possible to cope with voltage fluctuations of the commercial three-phase AC power supply.

Here, the tap winding 26 is provided inside the -modal main winding 25 and is arranged between the -modal main winding 25 and the secondary winding 22 located inside it. In addition, the primary winding 23
In this case, the inner peripheral surface of the tap winding 26 and the secondary winding 2
The inner main gap d1, which is the distance between the outer peripheral surface of
The outer circumferential surface of the primary winding 23 is set larger than the outer main gap d2, which is the distance between the outer circumferential surface of the primary winding 25 and the inner circumferential surface of the secondary winding 24. This makes the values of the positive group impedance and negative group impedance equal.

According to this embodiment having such a configuration, the tap winding 26 of the primary winding 23 is placed between the negative main winding 25 and the secondary winding 22 located inside it, that is, on the inside where the gap is originally large. Since the tap winding 12 is placed on the main gap side l side, compared to the conventional configuration (see Fig. 5) in which the tap winding 12 is placed on the outside main gap side where the gap is narrow, the number of turns of the tap winding is the same, that is, the diameter Considering that the thickness dimension in the direction is the same, the rate of change in leakage magnetic flux due to tap switching becomes small. Therefore, fluctuations in impedance are also reduced. Therefore, the difference between the positive group impedance and the negative group impedance due to tap switching can be made smaller than in the past. As a result, it is possible to prevent distortion of the output waveform of the cycloconverter from increasing as much as possible. In this embodiment, the distribution of leakage magnetic flux that affects the positive group impedance and the negative group impedance is as shown in FIG. 2. In FIG. 2, the leakage flux distribution when the entire tap winding 26 is energized, that is, at the highest tap, is shown by a solid line, and the leakage flux distribution when the entire tap winding 26 is not energized, that is, at the lowest tap, is shown by a dashed line. .

By the way, in the conventional configuration (see Fig. 5), the tap winding 12 was originally placed on the outer main gap side where the gap was narrower, so the outer circumferential surface of the tap winding 12 and the inner circumferential surface of the outer secondary winding Since the space between the tap winding 12 and the tap winding 12 is narrow and it is not possible to pass the tap lead wire through this gap, tap lead parts must be provided at both the upper and lower ends of the tap winding 12. For this reason, the work of connecting the lead wire to the outlet of the tap must be performed at both the upper and lower ends of the tap winding 12, which has the drawback of poor workability. On the other hand, in the above embodiment, the tap winding 26 is disposed between the negative main winding 25 and the secondary winding 22 located inside thereof, and further,
Since the gap between the inner circumferential surface of the tap winding 26 and the outer circumferential surface of the inner secondary winding is set large, the lead wire of the tap can be passed through this gap. Therefore, the tap outlet can be provided, for example, only on the upper end side of the tap winding, and the workability of connecting the lead wire to the tap outlet can be improved.

In the above embodiment, the inner main gap is the same as the conventional one (see FIG. 5), but in this case, when the tap winding 26 is not energized, the radial thickness of the tap winding 26 is The inner main gap is wider than before,
The leakage magnetic flux increases and the impedance increases. Therefore, paying attention to this, instead of the above example,
When the tap winding is not energized, that is, the gap between the inner peripheral surface of the primary main winding and the outer peripheral surface of the inner secondary winding is
(see figure) may be set to be the same as the inner main gap. In this case, since the inner main gap (the gap between the inner circumferential surface of the tap winding and the outer circumferential surface of the inner secondary winding) can be made smaller than before, the primary winding and the outer secondary winding The diameter of each winding can be made small, the overall structure can be made smaller and lighter, and the amount of conductors used can be reduced, as well as losses can be reduced.

FIG. 3 shows a second embodiment of the present invention, and the differences from the first embodiment will be explained. As shown in FIG. 3, the secondary winding 27 that replaces the secondary winding 22 consists of two partial secondary windings 27a and 27b arranged one above the other. Further, a primary winding 28 that replaces the primary winding 23 is composed of a negative main winding 29 and a tap winding 30. The above-mentioned main winding 29 is composed of two main main windings 29a and 29b arranged above and below. The tap winding 30 also includes two partial tap windings 30a and 3 arranged above and below.
Consists of 0b. Furthermore, a secondary winding 3 replacing the secondary winding 24
1 is two partial secondary windings 31a and 3 arranged above and below.
Consisting of 1b. This makes the structure equivalent to the first embodiment in which two cycloconverter transformers are provided above and below.

Therefore, in this second embodiment, the same effects as in the first embodiment can be obtained, but especially when two cycloconverter transformers shown in the first embodiment are used, the above-mentioned One transformer according to the second embodiment can be used.

[Effects of the Invention] As is clear from the above description, the present invention has a configuration in which the tap winding of the next winding is arranged between the main winding and the secondary winding located inside the main winding. Therefore, the difference between the positive group impedance and the negative group impedance due to tap switching can be minimized, and distortion of the output waveform of the cycloconverter can be prevented as much as possible, which is an excellent effect.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, in which FIG. 1 is a partial longitudinal sectional view and FIG. 2 is a diagram showing the distribution of leakage magnetic flux. Further, FIG. 3 is a diagram corresponding to FIG. 1 showing a second embodiment of the present invention. FIGS. 4 to 6 show the conventional configuration,
FIG. 4 is an electrical configuration diagram, and FIGS. 5 and 6 are diagrams corresponding to FIG. 1 and FIG. 2, respectively. In the drawing, 22.27 is a secondary winding, 23.28 is a primary winding, 24.31 is a secondary winding, 25.29 is a primary main winding, 2
6.30 indicates a tap winding.

Claims (1)

[Claims] 1. A primary winding consisting of a primary main winding and a tap winding connected to an AC power source, and two secondary windings installed inside and outside this primary winding and connected to the positive group converter and negative group converter of the cycloconverter, respectively. A transformer for a cycloconverter, characterized in that a tap winding of the primary winding is arranged between the primary main winding and a secondary winding located inside the primary main winding. .