RU2373626C2 - Ac/dc converter - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: ac/dc converter can be used dc power supply circuits, primarily, with LV supply. Proposed converter comprises three-phase transformer (1) with two groups of secondaries, each comprising star-connected winding and reversed-star-connected winding. Secondaries of every group are connected by their zero leadouts that make the device output leads and twelve gates (2…14). The number of winding turns making aforesaid stars and that making reversed stars are related as

. Six gates (3, 5, 7, 9, 11, 13) are connected into six-gate ring to have gate similar electrodes connected in pairs, that is, anodes of the pairs of gates (3, 13; 5, 7; 9, 11) and cathodes of the pairs of gates (3, 5; 7, 9; 11. 13). Phase leadouts a, b, c of winding of the star of one group of secondaries are connected, via gates (13, 5, 9), with phase leadouts b', c', a', while by gates (3, 7, 11) they are connected with phase leadouts c', a', b' of windings of the star of the other group of secondaries. To the points of connection of anodes of the pairs of gates (5, 7; 9, 11; 3, 13) connected are phase leadouts b, c, a of star windings of one group of secondaries and anodes of gates (6,10, 2), the cathodes of which are connected to phase leadouts y', z', x' of windings of reversed start of the other group of secondaries. To the point of connection of cathodes of the pairs of gates (3, 5; 7, 9; 11, 13) connected are phase leadouts c', a', b' of the star windings of the other group of secondaries and cathodes of gates (4, 8, 12), cathodes of which are connected to phase leadouts z, x, y of reversed star windings of the first group of secondaries. Load 14 is connected to zero pints.

EFFECT: reduced weight and sizes.

3 dwg

Description

The invention relates to the field of converter technology and may find application for supplying direct current consumers, mainly with low-voltage power.

Known AC to DC converters, in which, for the best use of transformers, multiphase systems are formed by combining three-phase stars and zigzags with a surge reactor (Kaganov I.L. Electronic and ionic converters. M .: Art. 1960).

The disadvantage of these converters is the need to introduce a surge reactor.

A known converter of alternating current to direct current, containing a three-phase transformer, the primary winding of which and two secondary are connected to a star, the common point of one secondary winding connected to the first output terminal, and six valves connected in series so that they have the same electrodes in pairs (a .s. SU No. 265254, IPC Н02М 7/12, publ. 02.14.1966).

This converter provides only six-pulse rectification.

Closest to the invention adopted as a prototype is an AC to DC converter (AS SU No. 803089, IPC Н02М 7/06, publ. 02/07/1981), which provides twelve-pulse rectification and contains two three-phase transformers with primary windings connected in one transformer into a star, in the second into a triangle, and with secondary windings made in each transformer according to the star and reverse star scheme, connected by zero points, and twelve valves forming a twelve-valve ring structure, won paired electrodes compounds of similar valves, each phase secondary windings of the first transformer is connected to the combined power of the same name electrodes two gates through which it is connected with two phases of the second transformer secondary winding having a relative phase shift of (1 ± _^1/6) π e. hail. relative to the first, and the common connection points of the secondary windings in each transformer form two output terminals.

The disadvantage of this converter is its large overall dimensions, due to the high power of the secondary windings and the use of two transformers.

The objective of the invention is the creation of an AC to DC converter having lower overall dimensions.

, при этом шесть вентилей соединены в шестивентильное кольцо так, что попарно объединены одноименные электроды вентилей, каждая пара вентилей соединяет фазный вывод обмотки звезды, размещенной на одном из стержней трансформатора, с двумя фазными выводами обмоток другой звезды, размещенных на других стержнях трансформатора, а к каждой точке соединения одноименных электродов пар вентилей, к которой подключен вывод обмотки звезды, размещенной на одном из стержней трансформатора и принадлежащей одной из групп вторичных обмоток, подключен электрод такого же наименования незадействованного вентиля, второй электрод которого соединен с выводом обмотки обратной звезды другой группы вторичных обмоток, размещенной на том же стержне трансформатора.This task is achieved by the fact that the AC-to-DC converter contains a three-phase transformer and two groups of secondary windings, each of which contains a star-shaped winding and a star-shaped winding connected by zero points forming in each of the secondary groups windings is one of the output terminals of the device, and twelve gates, and the ratio of the same number of turns for star windings to the same number of turns for reverse windings is

in this case, six valves are connected in a six-valve ring so that the valve electrodes of the same name are combined in pairs, each pair of valves connects the phase output of the star winding located on one of the transformer rods with two phase outputs of the windings of another star located on the other transformer rods, and each connection point of the same name electrodes of the valve pairs, to which the output of the star winding is connected, located on one of the transformer rods and belonging to one of the secondary winding groups, is connected Electrode same here unactuated valve, the second electrode is connected to the terminal of the feedback winding stars of another group of the secondary windings placed on the same shaft transformer.

Figure 1 shows a circuit diagram of the proposed Converter; figure 2 - vector voltage diagrams presented in the form of amplitude-phase portraits of the voltages of the phase windings, and detailed vector diagrams explaining the principle of formation of the vectors of the resulting voltages; figure 3 - diagram of the windings and valves of the Converter.

. Шесть вентилей 3, 5, 7, 9, 11, 13 соединены в шестивентильное кольцо так, что попарно соединены одноименные электроды вентилей: аноды пар вентилей 3, 13; 5, 7; 9, 11 и катоды пар вентилей 3, 5; 7, 9; 11, 13.The Converter contains a three-phase transformer 1 with two groups of secondary windings, each of which contains a winding made according to the star pattern, and a winding made according to the reverse star pattern. The secondary windings in each group are connected by zero points, O - in one group and O '- in another, forming the output terminals of the device, and twelve valves 2 ... 14. The number of turns of the windings making up the stars, and the number of turns of the windings making up the inverse stars are in the ratio

. Six valves 3, 5, 7, 9, 11, 13 are connected in a six-valve ring so that the valve electrodes of the same name are connected in pairs: anodes of pairs of valves 3, 13; 5, 7; 9, 11 and cathodes of pairs of valves 3, 5; 7, 9; 11, 13.

Phase leads a, c, from the star windings of one group of secondary windings are connected respectively by valves 13, 5, 9 with phase leads b ', c', a ', and valves 3, 7, 11 with phase leads c', a ', b '' star windings of another group of secondary windings.

To the connection points of the anodes of the pairs of valves 5, 7; 9, 11; 3, 13, respectively, the phase terminals b, c are connected, and the star windings of one group of secondary windings and the anodes of the valves 6, 10, 2, the cathodes of which are respectively connected to the phase terminals y ', z', x 'of the reverse star windings of another group of secondary windings. To the connection points of the cathodes of pairs of valves 3, 5; 7, 9; 11, 13, respectively, the phase terminals c ', a', b 'of the star windings of another group of secondary windings and the cathodes of the valves 4, 8, 12 are connected, the anodes of which are respectively connected to the phase terminals z, x, of the reverse star windings of the first group of secondary windings.

A load 14 is connected to the zero points O and O '.

. При таком соотношении чисел витков обеспечивается равенство результирующих напряжений и требуемый фазовый сдвиг между ними 30 эл. град.The principle of operation of the Converter (Figure 1) is illustrated by vector voltage diagrams, presented in the form of amplitude-phase portraits of the voltage of the phase windings that make up two asymmetric six-phase voltage systems of groups of secondary windings, and a combined vector diagram unfolded on the phase plane, showing the principle of formation of the resulting voltages presented vectors S1-S12 (Figure 2). In each group of secondary windings galvanically connected to each other, the ratio of the number of turns of the phase windings making up the stars to the numbers of turns of the phase windings making up the inverse stars is

. With this ratio of the number of turns, the equality of the resulting voltages and the required phase shift between them of 30 el. hail.

The formation of a 12-pulse rectified voltage at the load occurs in accordance with the vector diagrams, which in Fig.2 are combined with the current compositions of the phase portraits of the voltage of the secondary windings. So, the first vector of the resulting voltage S1 is the sum of the collinear phase vectors of the phase voltages of the secondary phase windings o - a and x'-o 'of the transformer. Vector S2 is a linear voltage vector obtained from the phase voltages of the windings o-a and c'-o '. During the period, twelve identical resulting stresses are formed, forming a symmetric 12-phase system.

The scheme of operation of the windings and valves (Figure 3), obtained from the analysis of the diagrams in Figure 2, allows you to determine that all the windings forming stars work 90 el. hail., and windings forming backward stars, work 30 e. hail. over a period. All valves have a conductivity angle of 30 el. hail. The load current in the ripple interval flows around one valve. The order of entry of the valves 2 ... 13 in the work is reflected in their numbering on the diagram (Figure 1).

Based on the geometric construction of the diagrams of formation of the vectors of the resulting stresses (Figure 2), the maximum value of the rectified voltage with ideal switching and, accordingly, its average value are determined. Taking for the relative unit (pu) the voltage amplitude on the secondary phase winding having the largest number of turns, in accordance with the vector diagrams in FIG. 2, the average value of the rectified voltage U _do = 1,712 p.u.

According to the results of the analysis of the secondary windings (Figure 3) determined the power of the secondary windings, amounting to 1,762 P _d . The installed power factor of the transformer of the proposed Converter is equal to 1.387. The prototype has more similar indicators, since the power of the secondary windings of the transformers of the prototype is 1.814 P _d and two transformers are used in the prototype.

Thus, the proposed AC to DC converter, in comparison with the prototype, has lower overall dimensions, as the power of the secondary windings is reduced and the converter contains one transformer.

Claims (1)

An AC to DC converter containing a three-phase transformer and a group of secondary windings containing a star-shaped winding and a reverse-star winding connected by zero points forming one output terminal of the device and twelve valves, characterized in that the transformer is equipped with an additional group of secondary windings containing a winding made according to the star pattern and a winding made according to the reverse star pattern connected by zero points, forming and a second output terminal of the device, with the ratio equal to the number of turns of windings star to star identical to the inverse number of turns of the windings is equal to

in this case, six valves are connected in a six-valve ring so that the valve electrodes of the same name are combined in pairs, each pair of valves connects the phase output of the star winding located on one of the transformer rods with two phase outputs of the windings of another star located on the other transformer rods, and each connection point of the same name electrodes of the valve pairs, to which the output of the star winding is connected, located on one of the transformer rods and belonging to one of the secondary winding groups, is connected Electrode same here unactuated valve, the second electrode is connected to the terminal of the feedback winding stars of another group of the secondary windings placed on the same shaft transformer.

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