SU1638779A1 - Ac-to-dc rectifier - Google Patents

Abstract

The invention relates to electrical engineering, in particular to converter equipment, and can be used in power supply systems of electrified railways. The purpose of the invention is to simplify the implementation and increase the energy performance by reducing the structural asymmetry of the voltages of the secondary windings. The effect is due to the connection of the secondary windings 7 and 9 of the transformer into a forward and reverse closed zigzag. Each secondary winding of the transformer, together with a 6,7,8 or 9 rectifier bridge connected to it, forms a six-pulse rectifying section. At the output of the converter, the frequency of the net of the voltage ripple is twenty-four. New schemes for connecting the secondary windings allowed in r to make a more accurate selection of the numbers VIGKIE in any part of the winding. 4 il. 6 C, 8 Fgg1

Description

The invention relates to electrical engineering, in particular, to converter equipment, and can be used in power supply systems of 5 electrified railways, urban electric transport and the metro, as well as in the electrolysis industry.

The purpose of the invention is to simplify pea-10 lieation and increase the energy indices by reducing the constructive asymmetry of the voltages of the secondary windings.

Figures 1 and 2 illustrate the principle of a 15th converter circuit; on fig.Z - vector diagrams; in fig. 4 shows circuit connection variants of rectifying bridges.

The converter contains a transformer having one primary winding 1 connected in a star (figure 1) or a triangle (figure 2). Four secondary windings 2-5 are connected with triangle patterns (winding 2), 25 stars (winding 4), a straight closed zigzag (winding 3) and a reverse closed zigzag (winding 5). Each of the secondary windings is connected to the corresponding three-phase 30 rectifier bridge 6, 7, 8 or 9.. Each of the four secondary windings 2-5 of the transformer, together with the three-phase rectifying bridge connected to it (6-9), forms, g a simple six-pulse rectifying section. Between themselves, the rectifier sections can be connected along the DC circuit in parallel using three equalization reactors 10-12, in series-parallel (with one reactor 13) or in series (figure 4),

The converter works as follows .45

When a three-phase mains voltage transformer is applied to the primary winding 1, secondary voltages 2-5 induce voltages shifted in phase by f по50 in phase (Fig. 3a shows voltage vectors on each secondary winding, Fig. Sv - vector voltage chart on the load). The resulting rectified voltage on the load is twenty-four pulses.

The calculated power of the transformer winding, collected according to the closed zigzag scheme, obtained with regard to the effective current flowing through its component parts (W and Wj), with the same values of voltages of the secondary windings is equal to the power of the winding connected according to the zigzag scheme. Consequently, for twenty-four-pulse converters with the proposed connection scheme of the secondary windings and a connection circuit in a zigzag, transformers of equal power are necessary. The ratios between the voltages and the numbers of turns in the W, W, Wj parts of the windings for both variants of the connection scheme make it possible to select a combination of integers that provide the minimum asymmetry of the secondary voltages and Cft.

The use of a connection circuit in a closed zigzag in a transformer for a twenty-four-pulse converter instead of a connection in a zigzag allows for a more precise selection of the numbers of turns W in any part of the winding, while ensuring a minimal structural asymmetry.

Claims (1)

Claims of an AC-to-DC converter containing a transformer having one primary winding connected in a star or triangle pattern and four three-phase secondary windings connected to four three-phase rectifier bridges, the first and third of which are connected in triangle and star circuits, respectively and the second and fourth windings consist of two parts each, with the ends of the main parts of the second winding connected to the ends of the additional parts in the order corresponding to the forward part. Phase alternation, and in the fourth winding - in the order corresponding to the reverse phase alternation of the three-phase system, characterized in that, in order to simplify the implementation and increase the energy performance by reducing the constructive asymmetry of the secondary windings, the main parts start combined in each phase with the beginnings of additional parts located on the same rod, and serve as phase leads of the windings. (fftfftj Editor A. Ogar Compiled by E. Mel Ikova Tehred S. Migunova Proofreader S. Shevkun Fm.2 at i L u fi / -.rch 1GZ I , 0  f  AjibSn + Fig l