RU2340073C1 - Three-phase ac-to-dc voltage transducer (versions) - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: transducer contains neutral input pin, main three-phase controlled gate bridge, main paralleling reactors, main additional isolators, main two-terminal network, three-phase transformer, primary phase windings of which are connected by one terminals to input pins of this bridge, and by the others to phase input pins, secondary winding is star connected to neutral pin and connected by phase terminals to input pins of secondary gate bridge with blank input pin poles of which form its output pins. Additionally transducer contains N-1 (where N=2,3,4,...) pin groups of three-phase transformer primary winding connected i-th from specified N-1 pin groups from winding with turn number w_i counted from phase input pins to input pins i-th from N-1 additional three-phase controlled gate bridges similarly connected to N-1 pairs of paralleling reactor and additional gates, to input pins N-1 of additional two-terminal networks with common point of output pins connected to output pin of main two-terminal network. Input pin of the latter is connected to common point of main additional isolators. All additional isolators connected to two-terminal networks are diodes. Coupling chain on secondary side of three-phase transformer is short-circuited and on primary one contains winding connected as open delta with turn number less than turn number of the greatest segment of primary winding between its adjacent pin groups. Turn number of primary winding, from which i-th tap is provided, is equal to w_i

And intermediate pin of paralleling reactor winding of each bridge divides its turn number to parts in ratio

where: i=1,2,3,..., N is bridge sequence number; k=f(i)=2i-1,...,2N-1 is coefficient. If N=1, main two-terminal network is short-circuited, loading is connected between output pins of primary or/and secondary gate bridge, and blank output pins are short-circuited.

EFFECT: easy-to-control and high-quality transformation of three-phase AC-to-DC voltage with constant harmonic composition and inverse relationship of consumption current high harmonic amplitudes and thyristor activation angle.

6 cl, 12 dwg

Description

The invention relates to a conversion technique and can be used to convert a three-phase AC voltage to DC with a constant level of higher harmonics in the entire control range.

The inclusion circuit of an auxiliary valve shunting an active-inductive load in half-wave or half-wave rectifiers is widely known (see I. Kaganov, Electronic and ion converters. Part 3, 1956, p. 19 (current rectification in the presence of a shunt valve).

The disadvantage of this circuit is the need to use an additional valve, and the production of a continuous current in the load circuit is associated with the presence of a significant cathode inductance.

The set of reasons that impede the achievement of the required technical result is the need to use an additional valve complicating the converter, and its purpose does not provide for the possibility of increasing the energy performance in the required volume.

A known converter of three-phase AC to DC, containing a three-phase transformer, the primary winding of which is connected to a star and connected to the phase input terminals, two secondary windings connected each to a star connected by phase terminals to the input terminals of a three-phase controlled valve bridge, the output terminals of which are connected in series with a common load, a diode connected between the neutrals of the said secondary windings is opposed to a shunt diode connected in parallel with the mentioned that load (see AS No. 898572, class Н02М from 01/08/1979).

The disadvantage of this scheme is the need to use an additional valve, shunting the inductive energy of the load and thereby allowing additional smoothing of the ripple of the rectified voltage to the converter's capabilities. However, with an increase in the opening angle of the thyristors, the amplitude of these pulsations noticeably increases. Noncanonical harmonics are also present.

The set of reasons that impede the achievement of the required technical result is the need to use an additional valve complicating the converter, and its purpose does not provide for the possibility of increasing the energy performance in the required volume.

A known converter of three-phase AC to DC voltage, containing a three-phase transformer, the primary winding of which is connected to a star and connected to the phase input terminals, and the secondary winding is connected to a star with intermediate terminals connected to the input terminals of the bridge with the cathode group of thyristors and the main anode group of diodes, between the poles of which the load is switched on, an additional anode group of thyristors connected by anodes to the anodes of the above diodes, and by cathodes to the extreme terminals again windings of the said transformer, an additional anode group of diodes, the anodes of which are connected to the terminal of a normally open contact, the other terminal of which is connected to the anodes of the main anode group of diodes, and the cathode of each to one end of a chain of two resistors, the other end of which is to the corresponding extreme terminal of the said secondary windings, and the control electrode of each thyristor is connected to a common point of the corresponding pair of resistors (see OAJ Technical Report, 129. 202. AzNIETI. Baku city. 1969 "Thyristor exciter of electromagnetic brakes (EMT) for electric drive of a drawworks".

The disadvantage of this converter, in which additional groups of valves are used to force the voltage by switching on naturally switched thyristors without using a control system, is the inability to regulate the voltage using this additional group of thyristors.

The set of reasons that impede the achievement of the required technical result is that the configuration of the converter is intended only to force the voltage on the secondary side of the transformer and does not provide for the possibility of increasing the energy performance in the required volume.

Known three-phase single-phase AC to DC converter containing a three-phase transformer, the primary and secondary windings of which are each connected to a star, a group of valves connected to a star and connected to a secondary winding, and an additional three-phase winding connected to an open triangle, one end of which connected to the common point of the star of the secondary winding, and the other to one of the output terminals, and the output terminal is formed by a common point of the valve group, the turns of each phase are indicated th additional windings are located on the corresponding rod of the specified transformer opposite the turns of the secondary winding, and the number of turns of the additional winding in each phase refers to the number of turns of the secondary winding of the same phase as 1: 3 (see AS No. 797023, class H2M 7 / 12, 1978).

The disadvantage of this converter, in which an open triangle is used to compensate for the flux of forced magnetization, is the low quality of the conversion, which consists in the fact that with an increase in the opening angle of the thyristors, the amplitudes of the canonical higher harmonics also increase. The asymmetry of the network and the converter path leads to the appearance in the form of a rectified voltage of noncanonical harmonic with the frequency of the voltage of the supply network.

The set of reasons that impede the achievement of the required technical result is that the converter circuit, in which one of the open triangle outputs is connected to the output output formed by the common point of the valve group, is intended only to compensate for the forced magnetization flux, because the compensation winding conducts the 3rd harmonic current in the circuit conducting currents and other harmonics, and therefore cannot carry other functions.

By additional author. St. No. 860238, cl. Н02М 7.12 from 08/02/79 to the main bus. St. No. 752681, cl. Н02М 7/06, dated 04.02.76, a three-phase AC to DC converter is known, comprising a three-phase transformer, the primary windings of which, together with the pairs of counter-parallel-connected controlled valves connected in series with them, form a star connected to the phase input terminals, and the secondary the windings are connected in a star and connected to the rectifier bridge, while a set of secondary windings, a rectifier bridge and controlled valves are additionally introduced, and the primary windings through additional True counter-parallel connected valves are connected to the zero input terminal, and an additional set of secondary windings and an additional rectifier bridge, together with the main secondary windings and the main rectifier bridge, are connected according to a twelve-pulse rectifier circuit, an additional three-phase transformer is introduced, the primary windings of which are connected to a star, a common point which is connected to the zero input terminal, and the group of secondary windings is connected in a triangle.

The disadvantage of this converter is the complexity: 8 thyristors, 12 valves and 2 windings on the secondary side. It is also worth noting the low quality of the conversion, which consists in the fact that with an increase in the opening angle of the thyristors, the amplitudes of the canonical higher harmonics on the side of both direct and alternating current increase. The asymmetry of the network and the converter path leads to the appearance in the form of a rectified voltage of noncanonical harmonic with the frequency of the voltage of the supply network. Unequal switching angles are the reason that, with an increase in the load, the ripple voltage of the rectified voltage adjacent in phase becomes unequal in amplitude and thereby creates a non-canonical harmonic with a frequency of 300 Hz that increases in amplitude. In addition, the total number of control pulses supplied to the thyristors every 30 el. hail, equal to 18, and due to the need to ensure the operation of the converter in discontinuous current mode, which complicates the control system of the converter.

The set of reasons that impede the achievement of the required technical result is that the configuration of the converter circuit is intended only for the usual conversion (with low energy indices) of a three-phase alternating voltage to a constant, 12-pulse, with primary side control and the ability to compensate for harmful effects on the network zero sequence current, without obtaining large values of the rectification frequency multiple of 12.

A known Converter of three-phase AC to DC, containing a three-phase transformer, the ends of the primary phase windings of which are connected to the input terminals, and the beginning to the input of the bridge rectifier, made on controlled valves, the DC terminals of which are connected to one of the terminals of two equalization reactors, made each in the form of two series-connected windings, and the common connection points of both reactors are interconnected, and the other leads of the reactors are connected to the opposite m valve electrodes, the free electrodes of which are combined and connected to the zero input terminal, the secondary phase windings are connected to a six-beam star and connected to the second and third uncontrolled three-phase bridge rectifiers connected in parallel at the output, a smoothing reactor is connected between common points of the equalization reactors (see A.S. No. 1014109, CL H2M 7/17, 1981).

The disadvantage of this converter, which makes it possible to use two equalizing reactors with intermediate outputs on the primary side, similar in appearance to the proposed circuit of the elements, is the complexity: 8 thyristors, 12 valves and 2 windings on the secondary side. It should also be noted that the conversion quality is low, which means that with an increase in the thyristor opening angle, the amplitudes of the canonical higher harmonics on the side of both direct and alternating current increase, and it is impossible to obtain rectification frequency values that are multiples of 12. The asymmetry of the network and the converter path leads to the appearance in the form of a rectified voltage of noncanonical harmonic with the frequency of the voltage of the supply network. In addition, the need for a large number of control pulses supplied to the thyristors every 30 el. hail, complicates the control system of the converter.

The set of reasons that impede the achievement of the required technical result is that the intermediate output of the winding of each equalization reactor divides it into two equal parts. Conversion with greater frequency is not possible.

Closest to the proposed technical solution is a three-phase AC to DC converter containing a zero input terminal, a three-phase controlled valve bridge, each pole of which is connected to the extreme terminal of the winding of the corresponding equalization reactor, the other extreme terminal of which is with the same electrode of the additional valve, between a common point free electrodes of which and with a zero input terminal formed the primary connecting circuit, including the primary winding a single-phase transformer, and between the intermediate leads of the equalizing reactor windings a smoothing reactor is included, a three-phase transformer, the primary phase windings of which are connected by the corresponding terminals to the input terminals of this bridge, and the others are connected to the phase input terminals, the secondary winding is connected to a star with a zero terminal and connected to phase conclusions to the input terminals of the secondary valve bridge with a free input terminal, the poles of which are formed its output conclusions, and between the mentioned freedoms th input and the neutral pin is formed by connecting a secondary circuit comprising the secondary winding of said single-phase transformer (see. A.S. No. 1014109, class H02M 7/17, 1981).

The disadvantage of this converter, which makes it possible to use two equalizing reactors with intermediate terminals on the primary side, which is similar in appearance to the proposed circuit of the elements, is complicated: 8 thyristors and 2 transformers. It should also be noted the low quality of the conversion and the inability to obtain 12-fold values of the frequency of rectification: m = 24; m = 36.

The set of reasons that impede the achievement of the required technical result is that the intermediate output of the winding of each equalization reactor divides it into two equal parts. Conversion with greater frequency is not possible.

The problem to which the proposed technical solution is directed is to increase energy performance and simplify.

This problem in the first embodiment of the proposed solution is that in a three-phase AC to DC converter containing a zero input terminal, a three-phase controlled valve bridge, two additional valves, each pole of a three-phase controlled valve bridge is connected to the extreme terminal of the winding of the corresponding equalization reactor, the other extreme terminal which is connected to the electrode of the corresponding additional valve, while additional valves and valves of the valve bridge are connected to the extreme The primary windings are formed between the windings of the same equalization reactor with the same electrodes between the common point of the free electrodes of the additional valves and the zero input terminal, and the intermediate terminals of the windings of the equalizing reactors form the output terminals of the bridge, in addition, the converter contains a three-phase transformer, primary phase the windings of which are connected by one terminal to the input terminals of a three-phase controlled valve bridge, and by others to the phase input water, the secondary winding of a three-phase transformer is connected to a star with a zero terminal and connected by phase terminals to the input terminals of a secondary valve bridge with a free input terminal, whose poles are its output terminals, and a secondary connecting circuit is formed between the aforementioned free input and zero terminals of a secondary winding of a three-phase transformer , the intermediate output of the winding of each equalization reactor divides its number of turns into parts in a ratio equal to 1: √3, the smaller of which is counted I am from additional valves made in the form of diodes, the secondary connecting circuit is made short-circuited, and the primary connecting circuit contains a winding connected in an open triangle, the number of turns of which is less than the number of turns of the primary winding of a three-phase transformer.

The valves of the secondary valve bridge, to which the phase leads of the secondary winding of the three-phase transformer are connected, are controlled, according to each of them, a serial circuit containing a variable resistor and a diode is connected between its anode and the control electrode, a load and a smoothing reactor are connected between the output terminals of the secondary valve bridge and the output terminals of the three-phase controlled valve bridge are short-circuited.

The converter contains an additional three-phase transformer, the primary winding of which is connected to a star and connected by one terminal to a common point of the other terminals, respectively, to the phase and zero input terminals.

In the second variant of the proposed this problem is solved in that in the three-phase AC to DC converter containing a zero input terminal, the main three-phase controlled valve bridge, the main pair of additional valves, each pole of the main three-phase controlled valve bridge is connected to the extreme terminal of the winding of the corresponding equalization reactor main pairs of equalization reactors, the other extreme terminal of which is connected to the electrode of the main auxiliary valve, while The additional gates and gates of the indicated bridge bridge are connected to the extreme terminals of the winding of the same equalization reactor with the same electrodes, between the common point of the free electrodes of these additional valves and the zero input terminal, a primary connecting circuit is formed with the main bipolar connected in series with it, and intermediate terminals of the windings equalization reactors form short-circuited output leads of said controlled three-phase rectifier bridge, in addition, the converter contains a three-phase transformer, the primary phase windings of which are connected by one terminal to the input terminals of the specified three-phase controlled valve bridge, and the other by the phase input terminals, the secondary winding of the three-phase transformer is connected to a star with a zero terminal and connected by phase terminals to the input terminals of the secondary valve bridge with a free input terminal, the poles of which its output terminals are formed, and between the aforementioned free input terminal and the zero terminal the secondary winding of a three-phase transformer a secondary connection circuit is formed, additionally contains N-1 (where N = 2,3,4, ...) additional controlled three-phase valve bridges, pairs of surge reactors, pairs of additional valves and groups of terminals of the primary winding of a three-phase transformer, this i-th of these N-1 groups of terminals of the primary winding of a three-phase transformer of the number of turns w _i counted from the phase input terminals is connected to the input terminals of the i-th of N-1 additional three-phase controlled valve bridge, each of which is connected to the corresponding pairs of equalization reactors and additional valves from N-1, similarly to the connection of the main three-phase controlled valve bridge with the main populations of equalization reactors and additional valves, while to the common points of the free electrodes of additional valves from N-1 pairs the input terminals N-1 of additional two-terminal devices are connected, the common point of the output terminals of which is connected to the output terminal of the main two-terminal device, and the input terminal of the latter is connected to the common In the main auxiliary valves, each two-terminal contains a pair of on-parallel connected valves, one of which is controlled with the same electrode connection direction as the input terminal is identical to zero, all additional valves connected to the two-terminal are made in the form of diodes, the secondary connection circuit is made short-circuited, and the primary connection circuit contains a winding connected in an open triangle, the number of turns of which is less than the number of turns of the largest portion of the first egg winding of a three-phase transformer between its adjacent terminal groups, while the number of turns from which its i-th terminal is made is w _i

and the intermediate terminal of the equalization reactor winding of each bridge divides its number of turns into parts in a ratio equal to

where w _N is the number of turns of the primary winding of the three-phase transformer between its extreme terminals, w ₁ is the number of turns of the winding of the equalization reactor between the auxiliary valve electrode and the intermediate terminal, w ₂ is the number of turns of the winding of the equalization reactor between the intermediate terminal and the pole of the controlled valve bridge, i = 1,2,3, ..., N is the serial number of the three-phase controlled valve bridge, N is the total number of these bridges, k = f (i) = 2i-1, ..., 2N-1 is the ratio of the number of turns of the windings equalization reactor of the i-th bridge, as well as s three-phase transformer the primary winding between the i-E and the phase input terminals.

The valves of the secondary valve bridge, to which the phase terminals of the secondary winding of the three-phase transformer are connected, are controlled in parallel to each of them, and to each controlled valve of the two-terminal circuit between its anode and the control electrode, a serial circuit is connected containing a variable resistor and a diode, and between the output terminals of the secondary valve bridge included load and smoothing reactor.

The converter contains an additional three-phase transformer, the primary winding of which is connected to a star and connected by one terminal and a common point of the other terminals, respectively, to the phase and zero input terminals.

The technical result achieved in the first version of the proposed quantitatively consists in using one transformer instead of two, having 6 thyristors and two diodes instead of 8 thyristors, the ability to control all thyristors with only 6 pulses supplied to the thyristors every 60 el. hail. and providing 12-pulse regulation of the rectified voltage in the full range due to the lack of intermittent currents. A qualitative technical result consists in the fact that with a change in the opening angle α of the thyristors in the entire control range, there is no periodically repeating canonical and non-canonical dips in the form of a rectified voltage, which for any angle of opening of the thyristors has the form of a 12-pulse rectified voltage with fully open thyristors ( α = 0), and the amplitude of the pulsations in the absence of a smoothing reactor with an increase in α even decreases slightly. In this case, the amplitudes of the higher harmonic current consumption also decrease with increasing α, which is explained by the constancy of the shape of the rectified voltage, which varies only in amplitude, similar to mechanical voltage regulation by an autotransformer. When a smoothing reactor is turned on at the output of a secondary controlled gate bridge with two shunt diodes from the eight main gates, the form of the rectified voltage on the load in its circuit is converted into an absolutely straight line parallel to the abscissa axis, the amount of mixing of which relative to the ordinate axis depends on the α thyristors. In all cases, it is possible to compensate for the harmful effects of the zero sequence current on the converter by introducing an additional low-power three-phase transformer into the corresponding circuit of the converter path, the winding of which is connected to a star with a zero output.

The technical result achieved in the second embodiment of the proposed is the possibility of obtaining rectification with a frequency of m multiple of 12, i.e. m = 24, m = 36, etc. At the same time, the basic properties of the first option are preserved, i.e., a special smoothness of the rectified voltage shape, the inverse dependence of the amplitudes of the higher harmonic current consumption on α thyristors, a small number of valves, including controlled ones, on the primary side of the transformer, simplification of the control system.

, линейный ток сети I_л с подключенным компенсационным трансформатором и фазный ток первичной обмотки трехфазного трансформатора I_ф; на фиг.6 - принципиальная схема 12-пульсного преобразователя с вторичными тиристорным мостом и разомкнутым треугольником в первичной соединительной цепи; на фиг 7 - принципиальная схема 24-пульсного преобразователя с вторичным диодным мостом и разомкнутым треугольником в первичной соединительной цепи; на фиг.8 - временные диаграммы 24-пульсного выпрямленного напряжения Udα на выходе вторичного диодного моста со сглаживающим реактором L_d≠0 и без него L_d=0, при различных углах отпирания α тиристоров на первичной стороне в соответствии с картой импульсов, нумерация на которой соответствует нумерации этих тиристоров; на фиг.9 - векторная диаграмма напряжений 24-пульсного выпрямителя, приведенная к вторичной обмотке трехфазного трансформатора, где на каждом векторе результирующего выпрямляемого напряжения Ur указана соответствующая его образованию нумерация тиристоров и диодов управляющей части, а в скобках - диодов вторичного моста, где Ua₁b₁, Ua₁c₁, Ub₁c₁, Ub₁a₁, Uc₁a₁, Uc₁b₁ - вектора линейных напряжений питающей сети, прикладываемых к выводам, a₁, b₁, с₁ от части витков w₁ первичной обмотки трехфазного трансформатора при их отношении к числу витков вторичной обмотки, равном единице, а точки а₂, b₂, с₂ соответствуют прикладыванию тех же напряжений к большему числу витков w₂ первичной обмотки трехфазного трансформатора между выводами а₂, b₂, с₂ и фазными входными выводами А, В, С; на фиг.10 - временные диаграммы линейного тока сети I_л при подключении компенсационного трансформатора, фазного тока основного трансформатора Iw₁ между фазным входным и смежным с ним промежуточным выводами, линейных токов первого Iл₁ и второго Iл₂ управляемых мостов, в общем нулевом проводе I₀ и в нулевых проводах первого I₀₁ и второго I₀₂ управляемых мостов, токов I₁₁, I₁₂ и I₆₂, I₆₃ (попарно на 2-х общих осях абсцисс) в обмотках уравнительных реакторов с указанной нумерацией (2-й вариант); на фиг.11 - принципиальная схема 24-пульсного преобразователя с вторичным тиристорным мостом и разомкнутым треугольником в первичной соединительной цепи; на фиг.12 - детализированные фрагменты векторных диаграмм, показывающие получение результирующих векторов выпрямляемых напряжений Ur, при N=1 (m=12), N=2 (m=24) и N=3 (m=36) и коэффициенте трансформации, равном единице. На временных диаграммах 24-пульсного выпрямителя по оси абсцисс масштаб вдвое больше, чем для 12-пульсного выпрямителя.In Fig.1 shows a schematic diagram of a 12-pulse converter with a secondary diode bridge and an open triangle in the primary connecting circuit, Fig.2 is a timing diagram of a 12-pulse rectified voltage Udα at the output of the secondary diode bridge with a smoothing reactor L _d ≠ 0 and without he L _d = 0, at different angles α unlocking thyristors on the primary side in accordance with a pulse card, on which the numbering corresponds to the numbering of these thyristors 3 - voltage vector diagram of 12-pulse converter, rivedennaya to the secondary winding of the three-phase transformer, where an example of the first quadrant, U _ab and U _0b, U _a0 - respectively vector line and the phase voltage supply _{network, U c02, U a02, U} 0b2 and _{U c01, U a01, U 0b1} - respectively vector of equalizing voltages and their smaller parts, proportional to areas with a smaller number of turns of windings of equalizing reactors, Ur is the vector of the resulting rectified voltage; figure 4 is a timing diagram of the currents flowing through the controlled valves and windings of equalization reactors (option 1), where I ₁ and I ₁₁ , I ₁₂ , I ₁₃ , I ₁₄ are thyristor currents and in sections of the windings of equalizing reactors with the indicated numbering; figure 5 - timing diagrams of currents in the neutral wire I ₀ in the phase windings of an additional (compensation) transformer

, the line current of the network I _l with a connected compensation transformer and the phase current of the primary winding of a three-phase transformer I _f ; 6 is a schematic diagram of a 12-pulse converter with a secondary thyristor bridge and an open triangle in the primary connecting circuit; Fig. 7 is a circuit diagram of a 24-pulse converter with a secondary diode bridge and an open triangle in the primary connection circuit; on Fig - time diagrams of a 24-pulse rectified voltage Udα at the output of the secondary diode bridge with a smoothing reactor L _d ≠ 0 and without it L _d = 0, at different angles of unlocking α thyristors on the primary side in accordance with the pulse map, numbering on which corresponds to the numbering of these thyristors; figure 9 is a vector diagram of the voltages of a 24-pulse rectifier, reduced to the secondary winding of a three-phase transformer, where on each vector of the resulting rectified voltage Ur the numbering of thyristors and diodes of the control part corresponding to its formation is indicated, and in brackets are the diodes of the secondary bridge, where Ua ₁ b ₁ , Ua ₁ c ₁ , Ub ₁ c ₁ , Ub ₁ a ₁ , Uc ₁ a ₁ , Uc ₁ b ₁ are the linear voltage vectors of the mains applied to the terminals, a ₁ , b ₁ , s ₁ from the part of the turns w ₁ a three-phase transformer primary winding with respect to the number of secondary windings second winding is equal to unity, and a point a _2, b _2, c ₂ correspond to applying the same voltage to a larger number of turns w ₂ phase transformer the primary winding between the terminals a _2, b _2, c ₂ and the phase input terminals A, B, C ; figure 10 - time diagrams of the linear current of the network I _l when connecting a compensation transformer, the phase current of the main transformer Iw ₁ between the phase input and adjacent intermediate terminals, linear currents of the first Il ₁ and second Il ₂ controlled bridges, in a common neutral wire I ₀ and in the neutral wires of the first I ₀₁ and second I ₀₂ controlled bridges, currents I ₁₁ , I ₁₂ and I ₆₂ , I ₆₃ (in pairs on 2 common abscissa axes) in the windings of equalization reactors with the indicated numbering (2nd option) ; 11 is a schematic diagram of a 24-pulse converter with a secondary thyristor bridge and an open triangle in the primary connecting circuit; on Fig - detailed fragments of vector diagrams showing the receipt of the resulting rectified stress vectors Ur, at N = 1 (m = 12), N = 2 (m = 24) and N = 3 (m = 36) and the transformation coefficient equal to unit. In the time diagrams of a 24-pulse rectifier along the abscissa, the scale is twice as large as for a 12-pulse rectifier.

The Converter (figure 1) contains a three-phase controllable gate bridge on thyristors 1-6 and diodes 7, 8, equalization reactor 9 (10) with windings 11, 12 (13, 14), the common points of the opposite terminals of which are connected to short-term output terminals 15 (16) of said bridge, the beginning of the winding 11 (13) is connected to the cathodes (anodes) of thyristors 1, 3, 5 (2, 4, 6), the end of the winding 12 (14) is connected to the cathode (anode) of diode 7 (8) and the number of turns of winding 12 (14) is √3 times less than the number of turns of winding 11 (13). The common points of the opposite electrodes of thyristors 1-6 are connected to the beginnings of the primary phase windings of the transformer 17, the ends of which are connected to the phase input terminals A, B, C. The secondary winding of the transformer 17 is connected to a star and connected by the ends and the common point starts to the bridge input on the diodes 18 -25, between the output terminals 26 and 27 of which the load 28 is turned on. A transformer 17 is made of a winding 29 connected in an open triangle and connected at the beginning to the zero input terminal 0, and the end to the common point of the unlike electrodes of the diodes 7 and 8, i.e. according to the sequence in the circuit with the primary phase winding of the transformer 17. An additional transformer 30, the winding of which is connected to a star and connected by a group of the same terminals to the phase input terminals A, B, C, and the common point of the other terminals to the zero input terminal 0.

Obtaining at a certain load, sufficient for the normal operation of equalization reactors, at the input terminals of each of the bridges of the 12th converter, they are equal in amplitude and phase shifted by 30 e. hail of rectified voltages forming a 12-pulse rectified voltage (figure 2) is achieved by the ratio 1: √3 number of turns of windings of the equalization reactor 9 or 10. This is shown in the vector diagram (figure 3), where each rectified voltage vector Ur is the result of summation at one of the equalization reactors adjacent and phase shifted relative to each other by 30 el. hail, linear and phase voltage network. The magnitude of the rectified voltage, determined from the oblique triangles, is equal to:

Ur = 1,2241 · U _f · k _TP ,

where U _f is the phase voltage of the network, k _TP is the transformation coefficient.

In each discreteness interval, one of the equalization reactors generates a rectified voltage Ur, under the influence of which the rectified current branches, taking into account the balance of ampere turns, into two of its windings, and also flows through a circuit including a winding with a large number of turns of another equalizing reactor that performs the function cathodic inductance. At any time, the currents of the phase-adjacent windings of the transformer 17 differ from each other in magnitude (√3 + 1) times. The magnitudes of the magnetic fluxes created by them differ from each other by the same amount. The difference of these currents branches into a neutral wire. Under the action of unequal in magnitude and antiphase summed emfs adjacent phases (the third phase at this time performs the function of an additional anode inductance) in the winding 29 of the transformer 17, a resulting differential voltage emf of a triple frequency controlled by thyristors is directed opposite to the alternating component of the rectified voltage and having the same shape with a smaller amplitude. Under the action of this counter-EMF, the amplitude of the AC component of the rectified voltage decreases, and a recharge current is generated in the winding 12 or 14 of the reactor, which performs the function of a cathode inductance, which prevents the corresponding diode from switching off 7 or 8. At the same time, the absence of intermittent current mode is observed, which makes it possible replacement of valves 7, 8 with diodes. The shape of the recharge current in each discrete interval is a curve with increasing ordinates of instantaneous values (see I ₁₂ and I ₁₄ in figure 4), in contrast to the falling form of the initial curve of the main rectified current. The resulting current shape on all other elements of the converter circuit with an increase in the number of turns of the winding 29 and regardless of the unlocking angle of the thyristors approaches a rectangular-step. The amplitude of the make-up current is directly proportional to the value of the counter-EMF, and its flatness is to the anode inductance, determined by the choice of the number of turns of the winding 29.

It must be taken into account that for normal operation of the converter, a zero sequence current must flow between the common point of the opposite electrodes of the diodes 7, 8 and the zero input terminal 0. For this, the number of turns of the winding 29 must be less than the number of turns of the primary winding of the transformer 17 and can practically not exceed 25% of this number, taking into account the requirements for sufficient ripple suppression and an acceptable limitation of the control range, which are directly dependent on the magnitude of the back-EMF of the winding 29 (value 25 % is the value in relative units of the maximum difference of the ordinate of the variable component of the rectified voltage and its average value at a certain opening angle α of the thyristors). The nature of the effect of the back EMF of the winding 29 on the shape of the rectified current looks like a flattening of the tops of the half-waves of sinusoids, and the degree of this flattening, ceteris paribus, increases with an increase in the opening angle α of the thyristors from a value exceeding 78 el. hail, close to the limit of 105 e. hail. In other words, a decrease in the amplitude of the variable component is accompanied by an increase in the proportion of the constant component in the form of a rectified voltage. A further increase in the number of turns of the winding 29 to the maximum permissible value is possible, however, the increment of the effect on the shape of the rectified voltage becomes less noticeable.

Equalization reactors 9 and 10, alternately providing simultaneous conversion of linear and phase voltages, eliminate the initial inequality of switching resistances of adjacent pulsations by averaging them, i.e. prevent the formation of different switching angles, namely: the formation of non-canonical harmonics with a frequency of 300 Hz.

The switching moments of the sections of sinusoids forming in the winding 29 counter-emf with a frequency of 150 Hz, and at the output of the rectifier - a 12-pulse rectified voltage, are set in its positive and negative half-periods by the control system, and the points of free transition through zero are formed strictly symmetrically with respect to the ripples adjacent to these points, due to the mutual inductance of the windings of equalizing reactors, providing a phase shift of 60 el. hail, between switching diodes 7 and 8.

The absence of a non-canonical harmonic in the form of a rectified voltage with a frequency of 50 Hz is explained by the fact that surge reactors ensure the participation of a zero sequence current in each conversion cycle, which by definition cannot contain harmonics that are not a multiple of three.

The transformer 17, the voltages and currents of which on the secondary side repeat them on the primary side, serves not only to coordinate the voltages, but also to create a counter-EMF in the winding 29, which, together with the anode inductance, alternately connected its inactive phase, ensures the operation of the converter in continuous current mode in the entire range of regulation, which simplifies its management.

An additional low-power transformer 30 is designed to split the zero-sequence current of the converter into 3 identical parts, each of which simultaneously flows between the zero input terminal 0 and the corresponding phase input terminal. As a result, the harmful effect of the zero sequence current on the network is eliminated, since in the consumed line current it is absent.

Consider the operation of the Converter in figure 1 in more detail. In accordance with the card of pulses (figure 2) supplied to thyristors 1-6, they are unlocked in the following sequence: 1, 6, 3, 2, 5, 4 and work with diodes 7, 8 in sequence: 1-4-7 ; 1-4-8.1-6-8, 1-6-7; 3-6-7; 3-6-8; 3-2-8; 3-2-7; 5-2-7; 5-2-8; 5-4-8; 5-4-7. The sequence of operation of the diodes on the secondary side exactly repeats the operation of the valves and diodes on the primary side.

Suppose that a control pulse is applied to thyristor 4, it is open from the voltage U _ob applied to it, and current flows through it through a circuit including a zero input terminal 0, winding 29 of transformer 17, diode 7, winding 12 of reactor 9, output terminals 15, 16, winding 13 of reactor 10, anode-cathode of thyristor 4, primary phase winding of transformer 17, phase input terminal B. On the secondary side, diodes 20, 25 conduct current. The described starting cycle (possible when applying a pulse to any thyristor) precedes the converter entering normal slave mode you. After 60 email hail. the control pulse is fed to the thyristor 1, it opens from the rectified voltage Ur applied to it, resulting from the summation of the line voltage Uab at its winding 11 and the phase voltage U _0b at its winding 12 at the equalizing reactor 9, and the converter enters normal operation mode. The voltage amplitude Ur is the result of its equiangular phase shift relative to the summed voltages, determined by the selected ratio 1: √3 of the number of turns of the windings of the equalization reactor 9, inversely proportional (taking into account the balance of ampere turns) to the ratio of currents in these windings. This implies the inequality of the currents in the loaded windings of the adjacent phases of the transformer 17. At the same time, a voltage Ur of a smaller magnitude of the winding 29 forms a make-up current in the winding 14, which is a curve with increasing ordinates of instantaneous values. As a result of the superposition of the feed current curve on the initial curve of the main rectified current, the shape of the resulting rectified current curve remains almost unchanged at all thyristor unlock angles. The first interval of discreteness can be obtained without the previously described triggering cycle, if the control pulses are applied simultaneously to thyristors 1 and 4, i.e. in the general case, to two corresponding thyristors of the opposite groups of the controlled bridge, which, however, will require an additional triggering pulse in the first interval, which can then be removed.

After 30 email hail. after turning on the thyristor 1, the primary circuit current switches from diode 7 to diode 8 without additional intervention of the control system due to the fact that the unlock angle of the thyristor 1 set by the system is the actual unlock angle of diode 8, because the latter is included in the circuit of the winding 14 of the equalization reactor 10, which is connected by mutual inductance with its winding 13. Accordingly, the current of the secondary circuit is switched from diode 25 to diode 24, and the load current flows through the circuit, including diodes 19, 20, 24. Now the equalization reactor 10 forms the next with a phase shift of 30 el. hail. the rectified voltage vector Ur, and the reactor 9 performs the function of a cathode inductance.

Next, through 30 email. deg., when the anode potential of thyristor 6 becomes more negative than the potential of thyristor 4, switching from thyristor 4 to thyristor 6 occurs, and reactors 9 and 10 operate in the previous mode, forming the next phase voltage vector Ur on the equalization reactor 10.

Then, after another 30 email. grad., similar to the above, the primary circuit current without intervention of the control system switches from diode 8 to diode 7, reactors 9 and 10 again change their mode of operation, forming the next phase voltage vector Ur at equalization reactor 9.

During experiments, it was noted that the inclusion of a smoothing reactor between the output terminals 15, 16 does not affect the level of ripple of the rectified voltage at the load 28 connected between the output terminals 26, 27 on the secondary side, which is explained by shunting the energy of the smoothing reactor by diodes 7, 8. Together with the transfer of the load to the primary side (between the output terminals 15, 16) leads to the complete elimination of ripple on this load due to the same shunt action of the diodes 7, 8. To realize the detected effect with on By adjusting the smoothing reactor on the secondary side of the converter between the output terminals 26 and 27, it is necessary to make the valves 18-23 controlled so that the energy of the smoothing reactor can be shunted in the free circuit by the main diodes 24 and 25. In this case, the output terminals 15, 16 of the controlled bridge can be closed short or contain a different load.

The Converter (Fig.6) contains a three-phase controlled valve bridge on thyristors 1-6 and diodes 7, 8, equalization reactor 9 (10) with windings 11, 12 (13, 14), the common points of the opposite terminals of which are connected to short-term output terminals 15 (16) of said bridge, the beginning of the winding 11 (13) is connected to the cathodes (anodes) of thyristors 1, 3, 5 (2, 4, 6), the end of the winding 12 (14) is connected to the cathode (anode) of diode 7 (8) and the number of turns of winding 12 (14) is √3 times less than the number of turns of winding 11 (13). The common points of the unlike electrodes of thyristors 1-6 are connected to the beginnings of the primary phase windings of the transformer 17, the ends of which are connected to the phase input terminals A, B, C. The secondary winding of the transformer 17 is connected to a star and connected by the ends and the common point starts to the bridge input on the thyristors 31 -36 and diodes 24, 25, between the output terminals 26 and 27 of which the load 28 and the smoothing reactor 37 are connected. The transformer 17 has a winding 29 connected in an open triangle and connected at the beginning to the zero input terminal 0, and the end to the s point of diodes of opposite electrodes 7 and 8, i.e., according to the sequence in the circuit with the primary phase winding of the transformer 17. An additional transformer 30, the winding of which is connected to a star and connected by ends to the phase input terminals A, B, C, and by a common point it starts to the zero input terminal 0. According to each thyristor 32 ( 34 and 36) between its anode and the control electrode is connected a chain containing a series-connected diode and a variable resistor 18, 38, respectively (20, 39 and 22, 40). According to each thyristor 31 (33 and 35), a circuit is connected between its anode and control electrode, containing a series-connected diode and a variable resistor 19, 41, respectively (21, 42 and 23, 43). In this case, the variable resistor motors 38-40 and 41-43 are connected to the control electrodes of the respective thyristors 32, 34, 36 and 31, 33, 35.

The converter in FIG. 6 differs from the converter in FIG. 1 only in the configuration of the secondary side. Therefore, the operation of the converter in FIG. 6 differs from the operation of the converter in FIG. 1 only in those features that add additional elements of the secondary side.

Suppose that thyristors 1 and 4 and diode 8 are open as part of the above sequence for their inclusion. On the secondary side, under the action of rectified voltage Ur, the control current flows from the end of phase α of the secondary winding of the transformer 17 through a circuit including a diode 19, a resistor 41, a control electrode and a cathode of thyristor 31, output terminal 27, load 28, smoothing reactor 37, output terminal 26 , then branches through the diode 24 to the neutral of the secondary winding, and through the diode 20, the resistor 39, the control electrode is the cathode of the thyristor 34 to the end of the phase b of the secondary winding. The resistance value of the resistors is selected from such a calculation that the current flowing through the control electrodes of the thyristors 31, 34 is sufficient to unlock them. The thyristors 31 and 34 are unlocked from the rectified voltage Ur applied to them and, together with the diode 24, conduct the rated load current. After 30 email hail. thyristor 6 is unlocked, and thyristor 4 is locked by reverse voltage. Correspondingly, thyristor 36 is unlocked from the rectified voltage Ur next in phase, and when the control current flows through its control electrode and cathode, thyristor 34 is locked by reverse voltage, and the load current instead of thyristor 34 flows through thyristor 36. Thus, the natural switching of thyristors on the secondary side of the converter is realized without participation management system. (This possibility is also shown in FIG. 2, p. 92 of the publication “Manual on the methodology for preliminary and state scientific and technical examination of inventions”, VNIIPI, Moscow, 1985, as an example of controlling an AC electric drive). This ensures that the energy of the smoothing reactor 37 is released to the load 28 due to the shunt circuit, including the main diodes 24 and 25, i.e. without the use of additional shunt diodes. In this case, the form of the rectified voltage at the load 28 is converted into an absolutely straight line parallel to the abscissa axis, the amount of mixing of which relative to the ordinate axis depends on α thyristors, which makes it unnecessary to use a capacitor in the filter circuit. This makes it possible to reduce the number of turns of the winding 29 of the transformer 17 connected into an open triangle relative to the number of turns of its primary winding until a satisfactory compromise is achieved between reducing the number of turns of the winding 29 and increasing the inductance of the smoothing reactor 37. The possibility of realizing a continuous current mode in the entire control range is directly dependent on the values counter-EMF and anode inductance of the winding 29.

The feasibility of using a 12-pulse controlled rectifier lies in the high quality of the conversion, at which a zero level of higher harmonic rectified voltage is achieved in the entire control range, and, as a result, the inverse dependence of the amplitudes of the higher harmonic current consumption on the turn-on angle of the thyristors, as well as ease of control.

The converter (Fig. 7) contains the first three-phase controllable gate bridge on thyristors 1-6 and diodes 7, 8, equalization reactor 9 (10) with windings 11, 12 (13, 14), the common points of the opposite terminals of which are connected to short-circuit output conclusions 15 (16) of the aforementioned bridge, the beginning of the winding 11 (13) is connected to the cathodes (anodes) of the thyristors 1, 3, 5 (2, 4, 6), the end of the winding 12 (14) is connected to the cathode (anode) of the diode 7 (8) ) The common points of the opposite electrodes of thyristors 1-6 are connected to the intermediate terminals a ₁ , b ₁ , _{1 of the} primary winding of the transformer 17, the ends of which are connected to the phase input terminals A, B, C. The secondary winding of the transformer 17 is connected to a star and connected to the ends and common the point began to the output of the bridge on diodes 18-25, between the output terminals 26 and 27 of which the load 28 is turned on. The converter contains counterpairs connected in parallel: diode 44 with thyristor 45 and diode 46 with thyristor 47, according to the sequentially connected pair of diodes 48 and 49. K a ode thyristor 45 (47) 50 of diode (51) connected to the anode, the cathode of which is connected to one terminal of the variable resistor 52 (53), which is connected to the engine control electrode of the thyristor 45 (47). The converter contains a second three-phase controllable gate bridge on thyristors 54-59, equalization reactor 60 (61) with windings 62, 63 (64, 65), common points of opposite terminals of which are connected to short-circuit output terminals 66 (67) of the said bridge, the beginning of the winding 62 (64) is connected to the cathodes (anodes) of thyristors 54, 56, 58 (55, 57, 59), the end of the windings 62 (65) is connected to the cathode (anode) of the diode 48 (49). The common points of the opposite electrodes of the thyristors 54-59 are connected to the extreme terminals of the initial phase windings of the transformer 17. The anode of the diode 44 (46) and the cathode of the thyristor 45 (47) are connected to the common point of the diodes 7, 8 (48, 49). The cathodes of the diodes 44, 46 and the anodes of the thyristors 45, 47 are connected to the end of the winding 29 of the transformer 17 connected into an open triangle, the beginning of which is connected to the zero input terminal 0, formed by a common start point, connected to the star of the winding of the additional transformer 30, the ends of which are connected to the phase input terminals A, B, C.

In accordance with the claims, to obtain the rectification frequency m = 24, it is necessary to take: N = 2; i = 1, 2; k = 1.3.

For each surge reactor of the first bridge:

For each surge reactor of the second bridge:

As can be seen, the adopted ratio of the number of turns of equalization reactors provides the required phase angle of shift of unequal rectified voltages Ur ₁ and Ur _2, respectively, of the first and second controlled valve bridges. To obtain the equality of these stresses to the resulting rectified voltage:

Ur ₁ = Ur ₂ = Ur,

the ratio of the number of turns of the entire primary winding of a three-phase transformer to the number of turns between its intermediate terminals and the phase input terminals A, B, C is chosen equal to the voltage ratio:

Ur ₂ / Ur ₁ = 1.4227 · U _f / 1.0916 · U _f = 1.3033.

The number of turns of the winding 29 is chosen equal to the part of the number of turns of the primary winding of a three-phase transformer between the intermediate and phase input terminals.

In accordance with the map of pulses (Fig. 8) supplied to thyristors 1-6 or 54-59, they conduct current together with valves 7, 45 and 8, 44 or 48, 47 and 49, 46 in the order indicated on the resultant vectors rectified voltage (Fig.9). In this case, the order of inclusion of the corresponding diodes of the secondary bridge is shown on the same vectors in brackets.

Each controllable valve bridge alternately conducts current from two phase-adjacent resulting voltages, and the switching of bridges at the moments of supplying control pulses to the thyristors occurs due to the excess in the amplitude of the resulting voltage, which is included in the bridge's operation relative to the phase-switched off voltage that turns off the bridge, which, in its the turn is ensured by the selected ratio of the numbers of turns of equalization reactors 9, 10 and 60, 61.

Each time, from the moment of turning on to the moment of turning off the first controlled bridge on thyristors 1-6, only gates 7 and 45, or only gates 8 and 44, conduct current, i.e. during the operation of this bridge, the current in its neutral wire does not change its direction, and the thyristor 45 turns on automatically when there is a voltage of the corresponding polarity between the zero and phase input terminals. Therefore, thyristors 1-6 independently provide controllability of the first bridge.

Each time, during the operation of the second controlled bridge, the current in its neutral wire reverses its direction, and either the valves 49 and 46 or the valves 47 and 48 conduct the current, and the thyristor 47 turns on automatically when there is a voltage of the corresponding polarity between the zero and phase input conclusions. Therefore, thyristors 54-59 cannot independently ensure the controllability of the second bridge, which, nevertheless, is achieved thanks to triangle 29 and equalization reactors 60, 61, similarly to the first option, namely, under the action of a differential emf. of the triangle 29 in the windings 63, 65 of the equalization reactors 60, 61, the make-up current flows alternately, the valves 48, 49 cannot close, their control functions are taken over by the indicated reactors, the ripple of the rectified voltage is suppressed to a level approximately half that in the first embodiment, ceteris paribus, there is no intermittent current mode (see Fig. 10).

Valve pairs 44, 45 and 46, 47 are designed to ensure the autonomy of the flow of currents in the neutral wires of controlled bridges, i.e. each specified pair prevents the flow of the zero-wire current of one bridge along the circuit of another, which is facilitated by the sequence of switching on these valves (see Fig. 9).

The resulting zero sequence current flows between the common point of the valves 44-47, through the winding 29, the zero input terminal formed by the common point of the additional transformer 30 connected to the star of the winding, then branches into 3 equal parts, each of which flows into the network through one of the phase input conclusions A, B, C and also in the opposite direction alternately through one of the aforementioned valve pairs. The current flowing under the action of a differential emf. winding 29, always directed counter to the resulting zero sequence current, coincides with it in shape and is subjected to a general regulatory action.

All resulting currents of the primary side of the converter with the required transformation ratio are the currents of its secondary side.

The output terminals 15, 16 and 66, 67 of the controlled valve bridges, in contrast to the first embodiment, should always be short-circuited (see Fig. 7).

The converter (Fig. 11) contains the first three-phase controllable gate bridge on thyristors 1-6 and diodes 7, 8, equalization reactor 9 (10) with windings 11, 12 (13, 14), the common points of the opposite terminals of which are connected to short-circuit output conclusions 15 (16) of the aforementioned bridge, the beginning of the winding 11 (13) is connected to the cathodes (anodes) of the thyristors 1, 3, 5 (2, 4, 6), the end of the winding 12 (14) is connected to the cathode (anode) of the diode 7 (8) ) The common points of the opposite electrodes of thyristors 1-6 are connected to the intermediate terminals a ₁ , b ₁ , _{1 of the} primary phase windings of the transformer 17, the ends of which are connected to the phase input terminals A, B, C. The secondary winding of the transformer 17 is connected to a star and connected to a common point started and ends to the input of the bridge on thyristors 31-36 and diodes 24, 25, between the output terminals 26 and 27 of which the load 28 and the smoothing reactor 37 are connected. Anode of the diode 50 (51) is connected to the anode of the thyristor 45 (47), the cathode of which is connected with one output of a variable resistor 52 (53), to dv buckle which is connected a control electrode of the thyristor 45 (47). The converter contains a second three-phase controllable gate bridge on thyristors 54-59, equalization reactor 60 (61) with windings 62, 63 (64, 65), common points of opposite terminals of which are connected to short-circuit output terminals 66 (67) of the said bridge, the beginning of the winding 62 (64) is connected to the cathodes (anodes) of the thyristors 54, 56, 58 (55, 57, 59), the end of the winding 63 (65) is connected to the cathode (anode) of the diode 48 (49). The common points of the opposite electrodes of the thyristors 54-59 are connected to the extreme terminals of the initial phase windings of the transformer 17. The anode of the diode 44 (46) and the cathode of the thyristor 45 (47) are connected to the common point of the diodes 7, 8 (48, 49). The cathodes of the diodes 44, 46 and the anodes of the thyristors 45, 47 are connected to the end of the winding 29 of the transformer 17 connected into an open triangle, the beginning of which is connected to the zero input terminal 0, formed by the common point of the beginning of the additional transformer 30 connected to the star of the winding, the ends of which are connected to the phase input conclusions A, B, C. According to parallel to each thyristor 32 (34 and 36) between its anode and the control electrode is connected a circuit containing a series-connected diode and a variable resistor 18, 38 (20, 39 and 22, 40, respectively). According to each thyristor 31 (33 and 35), a circuit is connected between its anode and control electrode, containing a series-connected diode and a variable resistor 19, 41, respectively (21, 42 and 23, 43). In this case, the variable resistor motors 38-40 and 41-43 are connected to the control electrodes of the respective thyristors 32, 34, 36 and 31, 33, 35.

The converter in FIG. 11 differs from the converter in FIG. 7 only in the configuration of the secondary side. Therefore, the operation of the converter in FIG. 11 differs from the operation of the converter in FIG. 7 only in those features that add additional elements of the secondary side. These features are similar to the first embodiment of FIG. 6 and consist in the fact that the energy of the smoothing reactor 37 is released on the load 28 due to the shunt circuit, including the main diodes 24 and 25, i.e. without the use of additional shunt diodes. The operation of the shunt circuit suppresses small amplitude noncanonical harmonics with a frequency of 300 Hz (unequal switching conditions, namely, a change or unchanging direction of the zero sequence current during the operation of one of the primary bridges) and 600 Hz (unequal switching angles) that can occur at the output of the converter due to the heterogeneity of the operating modes of controlled valve bridges. In this case, the form of the rectified voltage at the load 28 is converted into a line with a very small undulation, the magnitude of the displacement of which relative to the ordinate axis depends on α thyristors, which eliminates the need for a capacitor in the filter circuit. The shunt circuit allows you to reduce the number of turns of the winding 29 connected into an open triangle of the transformer 17 relative to the number of turns of its primary winding until a satisfactory compromise is achieved between reducing the number of turns of the winding 29 and increasing the inductance of the smoothing reactor 37. To achieve the marked result in the converter of FIG. 11, unlike the Converter of Fig.6, ceteris paribus, requires approximately half the number of turns of the winding 29 of the transformer 17, which is explained by less the magnitude of the variable component of the rectified voltage, not exceeding 13% - taken in relative units of the maximum difference of the ordinate of the variable component of the rectified voltage and its average value at a certain opening angle α of the thyristors. In this case, the magnitude of the narrowing of the regulation range of the rectified voltage decreases by half.

If the anode potential exceeds the cathode of one of the diodes 18-22 and 19-23, the corresponding pair of diodes is unlocked, current flows through the pair of resistors 38-43 connected to them, the corresponding pair of thyristors 31-36 is unlocked, one in the cathode and the other in the anode group and the load current flows through these thyristors and one of the diodes 24, 25. The resistance value of the resistors 39-43 is chosen so that the current flowing through the control electrodes of the thyristors 31-36 is sufficient to unlock them.

In accordance with the claims, to obtain the rectification frequency m = 36, it is necessary to take: N = 3; i = 1, 2, 3; k = 1, 3, 5.

For each surge reactor of the first bridge:

For each surge reactor of the second bridge:

For each equalization reactor of the third bridge:

As can be seen, the adopted ratio of the number of turns of equalization reactors provides the required phase angle of shift of unequal rectified voltages Ur ₁ , Ur ₂ and Ur _3, respectively, of the first, second and third controlled valve bridges. To obtain the equality of these stresses to the resulting rectified voltage:

Ur ₁ = Ur ₂ = Ur ₃ = Ur,

the ratio of the number of turns of the entire primary winding of a three-phase transformer to the number of turns between the first group of intermediate terminals and the phase input terminals A, B, C is equal to the voltage ratio:

Ur ₃ / Ur ₁ = 1.5098 · U _f / 1.0572 · U _f = 1.4281,

and the ratio of the number of turns between the second group of intermediate terminals and phase input terminals to the number of turns between the first group of intermediate terminals and phase input terminals is equal to the ratio of voltages:

Ur ₂ / Ur ₁ = 1.2247 · U _f / 1.0572 · U _f = 1.1584.

The value in relative units of the maximum difference in the ordinate of the variable component of the rectified voltage and its average value at a certain opening angle α of the thyristors for the case N = 3 is about 9%. Therefore, to obtain smoothing rectification similar to 24-pulse (12-pulse) rectification, the number of turns of the transformer winding connected in a triangle can be a quarter less (almost three times less). Respectively less and narrowing the range of regulation. In this case, the largest portion of the primary winding, the transformer relative to which the number of turns of an open triangle is counted, is the portion between the phase input terminals and the intermediate terminals adjacent to them

In the general case of 12N-pulse rectification, the control of additional valves in the full range of only one controlled valve bridge connected to the extreme (N-m) terminals of the transformer primary winding is ensured by the presence of its additional winding connected in a triangle and equalization reactors. To control the remaining controlled valve bridges, it is sufficient to have 6 thyristors in each of them. This can be seen from the consideration of vector diagrams (see Fig. 12), because during operation of only one Nth controlled bridge connected to the Nth terminals of the transformer primary winding (for example, the 3rd bridge at N = 3 or the 2nd bridge at N = 2), switching of additional valves occurs due to a change in the direction of the resulting zero sequence current.

The feasibility of the general industrial use of a 24-pulse (N = 2) controlled rectifier lies in the relative simplicity, efficiency, and, compared with the first option, a half-reduction of the regulation range. A further increase in the frequency of rectification is advisable if it is necessary to protect the network from higher harmonics of a higher order.

Claims (7)

1. A three-phase AC to DC converter containing a zero input terminal, a three-phase controlled valve bridge, two additional valves, each pole of a three-phase controlled valve bridge is connected to the extreme terminal of the winding of the corresponding equalization reactor, the other extreme terminal of which is connected to the electrode of the corresponding additional valve, when additional valves and valves of the valve bridge are connected to the extreme terminals of the winding of the same equalization reactor electrodes of the same name, between the common point of the free electrodes of the additional valves and the zero input terminal, a primary connecting circuit is formed, and the intermediate terminals of the windings of the equalizing reactors form the output terminals of the bridge, in addition, the converter contains a three-phase transformer, the primary phase windings of which are connected by one terminal to the input terminals of a three-phase controlled valve bridge, and others - to the phase input terminals, the secondary winding of a three-phase transformer connected on to a star with a zero output and connected by phase terminals to the input terminals of the secondary valve bridge with a free input terminal, the poles of which form its output terminals, and between the mentioned free input terminal and the zero terminal of the secondary winding of a three-phase transformer, a secondary connection circuit is formed, characterized in that the intermediate output of the winding of each equalization reactor divides its number of turns into parts in a ratio equal to 1: √3, the smaller of which is measured from additional valves, in made in the form of diodes, the secondary connection circuit is made short-circuited, and the primary connection circuit contains a winding connected in an open triangle, the number of turns of which is less than the number of turns of the primary winding of a three-phase transformer. 2. The three-phase AC to DC converter according to claim 1, characterized in that the valves of the secondary valve bridge to which the phase terminals of the secondary winding of the three-phase transformer are connected are made controlled, in parallel with each of them, a serial circuit is connected between its anode and the control electrode containing a variable resistor and a diode, between the output terminals of the secondary valve bridge are included the load and the smoothing reactor, and the output terminals of a three-phase controlled valve Foot bridge are short-circuited. 3. The three-phase AC to DC converter according to claim 1, characterized in that it contains an additional three-phase transformer, the primary winding of which is connected to a star and connected by one terminal and a common point of the other terminals to the phase and zero input terminals, respectively. 4. A three-phase AC to DC converter containing a zero input terminal, a main three-phase controlled valve bridge, a main pair of additional valves, each pole of the main three-phase controlled valve bridge is connected to the extreme terminal of the winding of the corresponding equalization reactor of the main pair of equalization reactors, the other extreme terminal of which is connected with an electrode of the main auxiliary valve, wherein said additional valves and valves of said valve m the cores are connected to the extreme terminals of the winding of the same equalization reactor with the same electrodes, between the common point of the free electrodes of these additional valves and the zero input terminal, a primary connecting circuit is formed with the main bipolar connected in series with it, and the intermediate terminals of the windings of the equalization reactors form short output outputs mentioned controlled three-phase rectifier bridge, in addition, the Converter contains a three-phase transformer p, the primary phase windings of which are connected by one terminal to the input terminals of the specified three-phase controlled valve bridge, and the other to the phase input terminals, the secondary winding of the three-phase transformer is connected to a star with a zero terminal and connected by phase terminals to the input terminals of the secondary valve bridge with a free input terminal whose poles form its output terminals, and between the aforementioned free input terminal and the zero terminal of the secondary winding of a three-phase transformer, w a primary connecting circuit, characterized in that it further comprises N-1 (where N = 2,3,4, ...) additional controlled three-phase valve bridges, pairs of surge reactors, pairs of additional valves and groups of terminals of the primary winding of a three-phase transformer, i-i of said N-1 groups of three-phase terminals of the transformer primary winding to the number of turns w _i, measured from the phase of input terminals, input terminals connected to the i-th of the N-1 additional three-phase controlled rectifier bridge, each of which is connected with a corresponding pairs of equalization reactors and additional valves from N-1, similarly to the connection of the main three-phase controlled valve bridge with the main pairs of equalization reactors and additional valves, while the input terminals of N-1 additional two-terminal devices are connected to the common points of the free electrodes of additional valves from N-1 pairs , the common point of the output terminals of which is connected to the output terminal of the main two-terminal network, and the input terminal of the latter is connected to the common point of the main additional valves, each The first two-terminal contains a pair of on-parallel connected valves, one of which is controlled with the same electrode connection direction with respect to the zero input terminal, all additional valves connected to the two-terminal are made in the form of diodes, the secondary connection circuit is short-circuited, and the primary connection circuit contains a winding connected to open triangle, the number of turns of which is less than the number of turns of the largest portion of the primary winding of a three-phase transformer m adjacent its forward pin groups, wherein the number of turns which is formed from its i-th taps is w _i

and the intermediate terminal of the equalization reactor winding of each bridge divides its number of turns into parts in a ratio equal to

where w _N is the number of turns of the primary winding of the three-phase transformer between its extreme terminals, w ₁ is the number of turns of the winding of the equalization reactor between the auxiliary valve electrode and the intermediate terminal, w ₂ is the number of turns of the winding of the equalization reactor between the intermediate terminal and the pole of the controlled valve bridge, i = 1,2,3, ..., N is the serial number of the three-phase controlled valve bridge, N is the total number of these bridges, k = f (i) = 2i-1, ..., 2N-1 is the ratio of the number of turns of the windings equalization reactor of the i-th bridge, as well as s three-phase transformer the primary winding between the i-E and the phase input terminals. 5. The three-phase AC voltage converter according to claim 4, characterized in that in accordance with each controlled bipolar valve, a serial circuit is connected between its anode and control electrode and contains a variable resistor and a diode. 6. The three-phase AC to DC converter according to claim 4, characterized in that the valves of the secondary valve bridge to which the phase terminals of the secondary winding of the three-phase transformer are connected are controlled, according to which each circuit is connected in parallel between its input and control electrode, containing a variable resistor and a diode, and between the output terminals of the secondary valve bridge, a load and a smoothing reactor are included. 7. The three-phase AC to DC converter according to claim 4, characterized in that it contains an additional three-phase transformer, the primary winding of which is connected to a star and connected by one of the leads and a common point of the other leads to the phase and zero input terminals, respectively.

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