SU1580508A1 - Three-phase-to-dc voltage converter - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to converter technology, and can be used in high-current low-voltage multipulse rectification with a small number of diodes. The purpose of the invention is to increase efficiency. The effect is achieved in such a way that during the formation of a twelve-pulse voltage at the output of a twelve-voltage device, linear and phase voltages are alternately applied to the primary windings of single-phase transformers 13 and 14 through the corresponding thyristors 1-12. In this case, the role of the ratio of the number of turns of these windings lies in the fact that a linear voltage √3 times the phase voltage is applied to √3 times the number of turns. As a result, the magnitude of the magnetic flux of each transformer when switching voltages remains constant regardless of the number of transformers operating in each discrete interval. 2 Il.

Description

The invention relates to electrical engineering, in particular, to converter technology, and can be used with high-current low-voltage multipulse rectification with a small number of diodes.

The purpose of the invention is to increase efficiency.

FIG. 1 is a schematic diagram of the first private implementation of a converter; in fig. 2 - the same, the second chgst-Ny execution.

; The converter (fig. 1} contains thyristors 1-12, forming in pairs six two-terminal networks, single-phase transformers 13 and 14, and diodes 15-18. Soldering the primary windings 19 and 20 from the -p- part of the turns

of each winding, measured from its start (end) connected to the input terminal of phase A (C), are connected through the first two-terminal, formed oppositely connected in parallel by a pair of thyristors 3 and 9. The end (beginning) of the primary winding 19 (20) an anti-parallel connected thyristor pair 2, 8 (4, 10) (the second and third two-terminal) is connected to the zero input terminal, and through the counter-parallel- connected parallel thyristor pair 1, 7 (5, 11) (fifth and the sixth two-port) Connected to the end of the winding 21 of the transformer 13. The beginning of the winding 21 is connected to the beginning of the winding 22 of the transformer 14, the end of which is connected via an anti-parallel to the connected pair of thyristors 6 and 12 to the zero input terminal. The end of the winding 21 is connected to the start of the winding 23 of the transformer 13, and the beginning of the winding 24 is connected to the input terminal of phase B. The number of turns of the primary winding 21 (23) is equal to the number of turns of the primary winding 22 (24) and is 0.134 part (0.366 part) of the number of turns primary winding 19 or 20. The beginning of the secondary winding 25 (26) of the transformer 13 (14) is connected to the cathode of the diode 15 (16), and the end is connected to the cathode of the diode 17 (18). The anodes of the diodes are connected to the negative output 27 of the rectifier, the positive output 28 of which is formed by taps of the secondary windings 25 and 26, which divide their turns into effective parts.

The Converter operates as follows.

Suppose that a thyristor 12 is opened from a New network voltage triggered to it, between the zero and phase input terminals O and 8, and the current of the primary phase currents 21-24 flows through the thyristor 12 From the end to the beginning of the winding 22 from the beginning to the end of the windings 21 and 23 and from the end to the beginning of the Winding 24. At the same time, the load current (not shown) flows between the output terminals 28 and 27, then branches into two equal parts, one of which flows through the diode 17 from the end to the tap-off of the winding 25, and the other through the diode i 6 from start to

winding off the winding 26.

After 30 el. happy, the thyristor 1 is unlocked from the applied voltage of the UAB network between the phase input terminals A and B, and the thyristor 12 is recorded due to the fact that, due to the transformer connection between windings 19, 23 and 21 (24 and 22) to it reverse voltage is applied. When etsm load current continues to flow through the diodes 16 and 17.

5 Through 30 el.grad. the thyristor is unlocked

2, the thyristor 1 is locked by the reverse voltage applied to it due to the transformer connection between windings 19 and 23. Moreover, due to the transformer connection between windings 19 and 25, the anode potential relative to the cathode 16, which locks and de-energizes the windings 24, 23 and thyristor 12. As a result, the entire

G5, the on-current current flows through the diode 17 from the end to the tap-off of the winding 25, between the output terminals 28 and 27, and the current of the primary winding 19 flows from its beginning to the end through the thyristor 2.

0 Through 30 el.grad. the thyristor is unlocked

3, Јi thyristor 2 is locked due to an autotransformer connection between the parts of winding 19. The primary current flows through the thyristor 3 from the beginning to the tap of the winding 19

5 and from the tap to the end of the winding 20. In this case, the load current divides into two equal parts, one of which flows through diode 17, and the other through diode 18.

Through 30 ep.grad. the thyristor is unlocked

0 4, and to the thyristor Z, a reverse voltage is applied between the input pins 0 and L. In addition, when unlocking the thyristor 4, the potential of the anode relative to the cathode of diode 18 becomes greater than that of diode 17,

5 which locks and de-energizes the transformer 13 and the thyristor 3. As a result, the entire load current flows through the diode 18, and the primary phase current through the thyristor 4 from the beginning to the end of the winding 20.

0 Through 30 zl.grad. thyristor B is unlocked, and thyristor 4 is locked due to the fact that due to the transformer connection between the windings 24 and 20, a reverse voltage is applied to it. The primary current flows through the thyristor 5 from the beginning to the end of the winding 24, from the end to the beginning of the winding 23 and from the beginning to the end of the winding 20. At the same time, the load current splits into two equal parts, one of which continues to flow

through diode 18, and the other begins to flow through diode 15.

Through 30 el.grad. the thyristor 6 is unlocked, and the thyristor 5 is closed due to the fact that due to the transformer connection between the windings 22 and 20,24, as well as 21 and 23, reverse voltage is applied to it. The primary current flows through the thyristor b from the beginning to the end of the winding 24, from the end to the beginning of the windings 23 and 21 and from the beginning to the end of the winding 22. At the same time, the load current continues to flow through the diodes 15 and 18.

The sequence of turning on thyristors 1-12 corresponds to their numbering. In this case, the sequence of switching on the diodes is as follows: 16–17, 16–17, 17, 17–18, 18, 15–18, 15–18, 15–18, 15, 15–16, 16, 16–17.

In the process of forming a 12-pulse voltage rectifier at the output of the primary windings of transformers, linear and phase voltages are alternately applied to the primary windings through the respective thyristors. In this case, the role of the ratio of the number of turns of these windings lies in the fact that the linear voltage, 3 times greater than the phase voltage, is applied to V3 times the number of turns. So, for example, the linear voltage UBC between the phase input pins B and C is applied to the primary windings 20, 24 and 23, the sum of the given numbers of turns of which is equal to

  I

1 H2-nt-l 3, and the phase voltage UBO between the phase and zero input pins B and O is applied to the primary windings 24, 23, 21 and 22, the sum of the reduced numbers of turns equal to vfr-1, VT-1, 2- vT,. 2-V3

+

+

+ +

 1.B

2 2 2

As a result, the magnitude of the magnetic flux of each transformer when switching voltages remains constant, regardless of the number of transformers operating in each discrete interval.

The converter (Fig. 2) contains thyristors 1-12, which in pairs form six two-terminal circuits, single-phase transformers 13 and 14, and diodes 15-18. Desoldering of primary windings 19 and 20 from -p- part of turns

each winding, counted from its beginning, connected respectively to the input terminal A and B, is connected via the first two-terminal, formed by an anti-parallel connected thyristor pair 1 and 7. The end of the primary winding 19 (20) through an anti-parallel connected thyristor pair 2 and 8 ( 6, 12) (the second and third bipolar networks) are connected to the zero input terminal, and through anti-parallel connected thyristors 3, 9 (5. 11) (the fifth and sixth bipolar networks) are connected to the 5 end of the winding 21 of the transformer 13. The beginning of the winding 21 connected to the end ohm the winding 22 of the transformer 14, the beginning of which is connected through a counter-parallel-connected pair of thyristors 4, 10 (the fourth two-pole 10), to the zero input terminal. The end of the winding 21 is connected to the beginning of the winding 23 of the transformer 13, the end of the winding 23 to the beginning of the winding 24 of the transformer 14, and the end of the winding 24 to the 15th phase C output. The number of turns of the primary winding 21 (23) is equal to the number of turns of the primary winding 22 (24 ) and is 0.134 part (0.366 part) of the number of turns of the primary winding 19 or 20.

0 The beginning of the secondary winding 25 (26) of the transformer 13 (14) is connected to the cathode of the diode 15 (16), and the end to the cathode of the diode 17 (18). The anodes of the diodes are connected to the negative output 27 of the rectifier, the positive output 28 of which is formed by taps of the secondary windings 25 and 26, which divide their turns into equal parts.

The device of FIG. 2 operates similarly to the device of FIG. 1. In this case, the sequence of switching on the thyristors also corresponds to their numbering. The amplitude and duration of the current in the equally designated transformer windings and the valves are the same.

5 The increase in efficiency is achieved by reducing active losses in transformers and diodes due to a more economical operating mode of the transformer windings for current and voltage, and

0 diodes - over current. For example, a comparison of the sequence of switching on the diodes shows that in the known converter the angle of conduction of the diode is 120 electr., And the shape of its current contains four pulsations,

5 30 el.grad., And the amplitude of each intermediate pulsation is equal to the sum of the amplitudes of the extreme pulsations. In the proposed converter, the conduction angle of the diode is 150 electr. Grades, and the form of its current contains 5 pulsations, 30 EP each. hail., and the amplitude of only one of the intermediate pulsations is equal to the sum of the amplitudes of any two of its other pulsations. Since the amplitudes of large current pulsations are equal to the amplitude of the 5 de load current, the average value of the diode current in the proposed and known converters are equal, and the current in the proposed one is 1.118 times smaller. Accordingly, the coefficient of form Kf of the diode current is smaller by 1.118 times, as well as the current value of the secondary current of the transformer. This leads to a decrease in power losses in the diodes in proportion to the square Kf, which is included as a multiplier in the term of its main losses, as well as in the secondary windings of transformers. The calculated power of the secondary windings also decreases.

The ratio of active losses in the primary windings of the known and proposed converters is proportional to the ratio of the calculated powers of these windings. Proceeding from the fact that in comparable devices of the same name windings Wi, W2 have the same given numbers for current work clamping, there is no A / C winding with a reduced number of turns Wa 0.732 (Wi +) and VT is less current than A / 4 winding, and W4 winding is divided into two parts Vita.i m L / 4.2, the smaller of which L / 4.1 flows around the same current as winding, and larger W4.2 in Vj- T times big, you can

p5

calculate that, as a result, the calculated power of the primary windings of transformers in the proposed converter turns out to be 1.22 times less than in the known. The analysis shows that this is happening, despite the increase in the YG times the calculated

3

power in the winding W4.2. precisely because of the reduction in the reduced number of turns of the primary windings of each transformer by Wa.

The proposed technical solution makes it possible to perform the secondary side of the converter also according to a full-wave rectifier circuit. In this case, the secondary winding of each single-phase transformer is connected to the input of the corresponding bridge rectifier, the outputs of which are connected to the common load. This leads to the threat of the design and reduction of the rated power of the transformer, but doubles the number of diodes. A comparison of the known and proposed converters with a doubled number of diodes shows that in the latter the efficiency is higher due to the reduction of active losses in both transformers and diodes.

In the proposed converter, it is possible to connect both to the natural and to the artificial zero input, formed by the neutral of the primary phase windings of an additional low-power three-phase transformer connected to the phase input terminals. With STL M, the secondary phase windings of this transformer can be connected to triangle.

The technical advantage of the proposed solution is the smaller given number of turns of the primary windings of each toansformatr by an amount equal to 5 (0.732 {Wi + W2).

Claims (1)

Formula and test of a three-phase alternating voltage to constant voltage converter, containing six two-terminal circuits made 0 in the form of counter-parallel connected controlled valves, two single-phase transformers with secondary phase overlays connected to the inputs of single-phase rectifiers , the outputs of which are connected in parallel, in the form of a rectifier with the number of gates, a multiple of four, with two first primary phase oOmotki, connected by one pair of opposite or like extreme terminals 0 of both vol. outflow to two phase input pins, intermediate leads from a part of their turns, counted from the indicated phase input pins, to the first two-terminal, and the other pair of end leads through the second and third two-terminal to the zero input output, with two second ones respectively or according to a series-connected primary phase windings forming 0 s. the fourth two-pole serial circuit connected between the zero input terminal and the common point of the fifth and sixth two-terminal circuits, with two third primary phase windings, is only 5 in order to improve the efficiency of the third primary phase windings respectively opposite or consistently and are connected between the third phase input output and the common 0 point of the fifth and sixth two-terminal networks, the free views of which are connected respectively to the second and third two-terminal networks, the ratio h The turns of the first, second, and third primary 5 phase windings is 1: (((vT-1) / 2. 5 Cc yp 02Јjj ft And / 1 .one , tV2 z / wi / 2J W /  42 75 J 20 .7 ft Ivj five % .f 22 i 2 15