SU915187A1 - Ac-to-dc converter - Google Patents

Description

The invention relates to a converter technique and is used to power various consumers.

The known converter of alternating current to direct, consisting of two six-phase circuits with a balancing reactor, each of which is made on a separate transformer ^ y

Such a converter, providing the possibility of supplying the load with a voltage of twelve times the frequency of the pulsations, is difficult because it contains two transformers and two equalizing reactors.

The closest in technical essence is an AC-to-DC converter containing a transformer with two three-phase secondary windings connected to each other in two reverse stars, two rectifiers, each of which is connected to the corresponding secondary winding according to its value

2

a left-hand circuit and a balancing reactor with a medium output connected between the common points of the valves of both rectifiers, with the average output of the balancing reactor and common points

5 star secondary windings form the output terminals, an additional group of valves, which are combined and their common point some conclusions of similar power electrodes forms a complement ⁰ tional output terminal, the other terminal of the power electrode of one of the additional rectifiers connected to the middle terminal of compensating reactor, and each of the other terminals

^{The 5} power electrodes of the remaining additional valves are connected to the secondary winding tap of the corresponding phase, which divides its turns in relation to (1-73/2): Тз / 2 [2].

^Yu. In the event that it is necessary to supply only one load with a voltage of twelve times the frequency of the pulsations, the second load is forced

915187

plays the role of a ballast, because without it it is impossible to obtain the desired frequency of pulsations. This reduces the efficiency of the converter. In addition, to supply one load, the converter contains a large number of additional gates, which causes its relative complexity, as well as a decrease in efficiency. c>

The purpose of the invention is to simplify and increase the efficiency when it is necessary to supply one load with a voltage of twelve times the frequency of the pulsations.

This goal is achieved by the fact that, 5

in the AC-DC converter containing a transformer with two three-phase secondary windings connected in relation to each other in two return stars, ₂₀ having a phase in each phase dividing the turns in relation to (1 - / 3/2):

: tGE / 2 \ and two rectifiers, each of which is connected to the corresponding secondary winding according to the zero 25 scheme, additional valves, one of the terminals of the same power electrodes of which are combined, and. each of the other terminals is connected to the tap of the corresponding phase of one of the ₃₀

secondary windings, an equalizing reactor with a middle lead connected between the common points of the valves of both rectifiers, the middle conclusion of the equalizing reactor and common points of the stars of the secondary windings form the output terminals, the common connection point of the additional valves is connected to the average output of the equalizing reactor.

35

40

FIG. 1 shows a converter circuit; in fig. 2 - diagrams of secondary phase voltages, rectified voltage and valve currents.

The converter contains a transformer consisting of secondary windings 1 and 2, connected according to the scheme of two reverse stars (primary windings are not shown), surge reactor 3 and valves 4-15 · Gates 4-6 and 7 ^- 9 form rectifiers, each of which is connected with the corresponding secondary winding 1 and 2 according to the zero scheme. Equalizing reactor 3

with an average output connected between the common points of the valves of both rectifiers. Additional valves 10-12 and

45

50

55

13 "15 also form rectifiers, each of which is connected in a zero circuit with the corresponding taps of secondary windings. The common connection point of valves 10-15 is connected to the midpoint of the surge reactor 3 and represents one output terminal of the converter; the other output terminal of the converter is formed by the common point of stars secondary windings 0. A load 16 is connected to the indicated output terminals of the converter. Each secondary winding is made with a tap dividing its turns in relation to (1): y ·.

The formation of a twelve-pulse voltage on the load 16 is carried out as a result of the application of rectified voltage on the corresponding intervals of two equal-magnitude six-pulse systems, shifted * by 30 el.grad. One six-pulse rectified voltage system is obtained as a result of the well-known principle of operation of the circuit with the actuator acting on the secondary emf system

^e b ' ^e c » ^e x> ^e h> Fu, through ventits'''x'>

whether 4-9 (figure 2). Other six-pulse system of the rectified voltage obtained from the plurality of secondary emf, θο * θχ, θχ ⁹ b2 9 which determines through valves 10-15 on the load 16 voltage operation principle of six-phase circuit with a null point. At the same time, on the interval of operation of each of the valves ΙΟΙ 5, through the corresponding valve 4-9, the magnetizing current of the surge reactor 3 passes, which ensures normal operation in the subsequent interval according to the well-known principle of the circuit with a surge reactor.

For example, in the interval when the emf e ^ is maximum and the current conducts valve 11, the electromotive voltage of the in-line section (e ^ - e ^ *) is balanced by the voltage at half of the reactor winding 3, and the magnetizing current passes through the valve 5 _# half of the winding superimposed on the load current of the valve 11. In the interval, a surge reactor works the same as in the well-known six-phase scheme. The ordinates of the voltage at the half winding of the equalizing reactor during the half of the period of its operation are shown in Fig. 2, with a secondary phase emf ^.

five

915187

6

Valves 4-9 of the converter, as seen in figure 2, conduct half of the load current Tc} / 2 6 for. 60 e. hail, each 10-15 - full load current 1 ^ within 30 hail.5 each.

Thus, if it is necessary to supply only one load with a constant voltage of twelve times the frequency of the pulsations, it is advisable to use the proposed device, which is simpler than the known one, since it contains one valve less and does not require additional ballast resistance 15 to create a magnetizing surge current reactor.

Simplification of the device results in a higher efficiency of the converter.

coils in relation (.1- / 3/2): Y ^ / 2 and two rectifiers, each of which is connected to the corresponding secondary winding according to the zero scheme, additional valves, one terminals of the same power electrodes of which are combined, and each of the other conclusions connected to the tap of the corresponding phase of one of the secondary windings, an equalizing reactor with a middle, output connected between the common points of the valves of both rectifiers, with the average output of the equalizing reactor and the common points of the stars of the secondary windings form the output terminals By the fact that, in order to simplify and increase the efficiency, the common point of connection of additional gates is connected to the average output of the surge reactor.

Claims (1)

Claim An AC-to-DC converter containing a transformer with two three-phase secondary windings connected to each other in two reverse stars with a tap in each phase, dividing