RU2754546C9 - Shuvayev multi-phase rectifier - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering, in particular, converter technology, and can be used in the design of secondary power supplies. A polyphase rectifier contains a set of transformers, n simple rectifiers, the number of which is either a multiple of two or three, connected to the load through p independent filter chokes, each of which has to the windings, the beginning of each winding is connected to the output of a simple rectifier, and their ends are connected to the load, the number of filter chokes and the number of their windings are related by the ratio n=pk. Each simple rectifier is designed as a six-phase, three-phase or full-wave midpoint rectifier.

EFFECT: invention reduces the volume and weight of elements of multiphase rectifiers with several filter chokes by reducing the volume and weight of a set of chokes, using multi-winding chokes and connecting to the load of each simple rectifier included in the multiphase rectifier through a separate winding.

4 cl, 4 dwg, 2 tbl

Description

The invention relates to the field of electrical engineering, in particular, converter technology, and can be used in the design of secondary power supplies for various purposes.

Various multiphase rectifiers are known and widely used: six-phase, twelve-phase, eighteen-phase, etc. [1]. Rectifiers consist of one or more three-phase transformers, one or more groups of single-phase transformers, the primary and secondary windings of which are connected in delta, star or zigzag, a set of diodes and a filter choke with one winding. Significant disadvantages of these rectifiers are the large volume and mass of transformers and diodes with heat sinks and low efficiency, due to the large amplitude and short duration of the current pulses flowing through the transformer windings and diodes. Let's conventionally call these multiphase rectifiers type I rectifiers.

The closest to the proposed technical solution, which is taken as a prototype, are multiphase rectifiers with several independent filter chokes, which are formed according to the same principle and consist of several simple rectifiers working together for a common load through their own filter choke (type II rectifiers) [2- 6].

Compared to type I rectifiers, type II rectifiers have a smaller volume and weight of transformers and diodes and a higher efficiency. However, the volume and weight of a set of chokes is greater than one choke, which is a disadvantage of rectifiers with multiple chokes.

In the proposed rectifiers (type III), the volume and weight of the set of transformers and diodes are the same as in type II rectifiers, and significantly less than in type I rectifiers, and the volume and weight of the filter choke set is less than in type II rectifiers.

In type III rectifiers, the volume and weight of a set of filter chokes is reduced by using one multi-winding choke instead of several chokes with one winding by replacing a group of chokes with one winding with one multi-winding choke.

Rectifiers of type III, like well-known rectifiers, can be made with the number of rectifying phases m = 6, 12, 18, 24, etc. They consist of 2-12 simple rectifiers. As simple rectifiers can be used rectifiers with the number of phases m _o = 6, 3, 2, i.e. six-phase, three-phase and full-wave with midpoint.

To achieve the technical result, each rectifier uses from one to four chokes with several windings. As a result, the number of chokes in type III rectifiers, in comparison with type II rectifiers, is reduced by 2-4 times, depending on the number of rectifier phases.

The following designations are accepted in the application materials:

m is the number of phases of a multiphase (composite, complex) rectifier with a midpoint, m = 6-24;

m _o - the number of phases of a simple rectifier, of which the multiphase rectifier consists, m _o = 6, 3, 2;

n is the number of simple rectifiers, n = m _o , n = 2, 3, 4, 6, 8, 9, 12;

p is the number of independent filter chokes, p = 1-4;

k is the number of filter choke windings, k = n / p, k = 2, 4, 6, 8, 9, 12;

T is the period of the supply voltage, T = 360 °;

Tg - harmonic voltage components, Tg = T / g;

g - order of harmonics, g = 2, 3, 4, 6, 8, 9, 12….

FIG. 1 and FIG. 2 shows the block diagrams of the proposed rectifiers. Rectifiers, the diagram of which is shown in Fig. 1, have the following parameters: m = 12, m _o = 3, n = 4, p = 2, k = 2 or m = 24, m _o = 6, n = 4, p = 2, k = 2. FIG. 2 - m = 12, m _o = 2, n = 6, p = 2, k = 3 or m = 18, m _o = 3, n = 6, p = 2, k = 3. Each polyphase rectifier contains a set of transformers 1, n simple rectifiers 2, p filter chokes 3. Each filter choke 3 is connected to load 4 through k windings 5. All chokes 4 windings are connected according to. The beginning of each winding is connected to the output of a simple rectifier 2, and their ends are connected to the load 4. The number of filter chokes and the number of their windings are related by the ratio n = pk. Output capacitor 6 is connected in parallel with load 4.

The number of transformers included in set 1 and the connection diagram of their primary windings correspond to the number of phases of the polyphase rectifier, and the secondary windings of the transformers are connected to a multiphase ray star. The primary windings of the transformers are connected directly in a delta or star or pre-connected in a zigzag and then in a delta or star. Rectifiers with the number of phases m = 18, 24 can be realized only by splitting the primary windings of the transformers into a zigzag, and then into a triangle or a star. The primary windings of the transformers included in set 1 are connected in such a way that their secondary windings form a system of voltage vectors shifted relative to each other by an angle of 360 ° / m. The offered rectifiers, like the well-known rectifiers, can be made using three-phase transformers with a magnetic circuit common to all phases or groups of three single-phase transformers.

In the proposed rectifiers, the number of transformers and the connection diagrams of their primary and secondary windings are the same as in the known rectifiers. The differences between the proposed rectifiers are in the number of filter chokes and the number of their windings.

Multiphase rectifiers with the number of phases m = 6, 12, 18, 24 and the number of filter chokes p = 1-4, made according to the ones shown in FIG. 1 and FIG. 2 block diagrams, have the main parameters shown in table 1.

As can be seen from table 1, rectifier circuits have a large number of modifications, as a result of which it is possible to select the optimal circuit from all the circuits, the parameters of which are given in this table. The optimal rectifier circuit provides the minimum volume and mass of its elements for the given initial data and output characteristics.

The rectified voltage curve of the rectifier, like any periodic function, can be expanded into a Fourier series consisting of constant and harmonic components of the cosine series (harmonics) according to the well-known expansion formulas [7-9].

The rectified voltage curves of the rectifiers, which are called simple and of which complex multiphase rectifiers consist, are arranged in rows consisting of the following harmonics: six-phase with a midpoint - 6, 12, 18, 24 ...; three-phase - 3, 6, 9, 12, ...; full-wave - 2, 4, 6, 8,…. For simple rectifiers, these harmonics are divided into the fundamental (OG), the frequency of which is equal to the number of rectifier phases m _o = 2, 3, 6, and higher (HF), the frequency of which is higher than the OG frequency - 2m _o , 3m _o , 4m _o ….

For complex multiphase rectifiers, the harmonic series consists of the exhaust gas, the frequency of which is equal to the number of its phases m, the lowest harmonics (LF), the frequency of which is lower than the frequency of the exhaust gas - m / n, 2m / n, 3m / n ... and higher (HF), the frequency of which above the exhaust gas frequency - m (n + 1), m (n + 2), m (n + 3)….

The amplitude of the fundamental harmonic determines the ripple factor of the rectified voltage.

Harmonic composition of the rectified voltage curves of simple and some polyphase rectifiers with m = 6, m _o = 3, n = 2; m = 6, = 2, n = 3; m = 12, = 3, n = 4 and m = 12, = 2, n = 6 are given in table 2.

Six-phase rectifiers are used both simple and complex, consisting of two three-phase or three full-wave rectifiers with a midpoint with one choke with two or three windings.

The proposed rectifier operates as follows.

The rectified voltage and current from the output of each simple rectifier 2 through the corresponding winding 5 of the chokes of the filter 3 are fed to the load 4. From the constant and harmonic components, the average value and the alternating component (ripple) of the rectified voltage of the polyphase rectifier are formed. The average voltage value is equal to the average voltage value of the simple rectifiers forming it.

The amplitude and average value of the current pulses flowing through the diodes and secondary windings of the transformers are n and m times less than the load current, respectively, and the duration of these pulses is 360 ° / m.

The formation of the output voltage ripple is carried out by summing the voltage harmonics of all the simple rectifiers that form it. Due to the fact that in polyphase rectifiers the voltage curves on the secondary windings of transformers are shifted relative to each other by an appropriate angle, the harmonic components of the output voltage of simple rectifiers also have a phase shift. LF and HF harmonics, which have the same amplitude and the same frequency, are in antiphase or have a phase shift relative to each other by an angle of 60 ° (2/3 Tg) and are mutually canceled on the filter chokes or on the load. Fundamental harmonics, which also have the same amplitude and frequency, coincide in phase, are smoothed by an equivalent inductive-capacitive filter with an appropriate filtering factor, and are fed to the load.

In more detail, we will consider the process of summing the harmonics of the output voltage of simple rectifiers using specific examples.

For a composite six-phase rectifier (m = 6, = 3, n = 2, k = 2, p = 1), the diagram of which is shown in Fig. 3, the odd harmonics of two simple rectifiers (d = 3, 9, 15 ...) are in antiphase (their phase shift angle is 60 ° (1/2 Tg) are fed to the filter choke windings and create corresponding magnetic flux harmonics in its magnetic circuit, which are mutually destroyed.

For a composite six-phase rectifier (m = 6, m _o = 2, n = 3, k = 3, p = 1) according to FIG. 4, even voltage harmonics of three simple rectifiers (g = 2, 4, 8 ...) are phase shifted relative to each other by an angle of 60 ° (1/3 Tg), are fed to the filter choke windings and create corresponding magnetic flux harmonics in its magnetic circuit, which are mutually compensated. Fundamental harmonics and even-numbered voltage harmonics (g = 6, 12, 18 ...) for both six-phase rectifiers coincide in phase and are smoothed by an inductive-capacitive filter.

For a twelve-phase rectifier consisting of two three-phase transformers, the primary windings of which are connected in a delta and a star, four simple rectifiers 1-4 and two filter chokes 1, 2 with two windings (m = 12, m _o = 3, n = 4, k = 2, p = 2), the structural diagram of which is shown in Fig. 1, is as follows. Odd voltage harmonics 3, 9, 15, rectifiers 1, 2 are in antiphase, fed to choke 1; rectifiers 3, 4 - to choke 2 and are mutually destroyed.

The sixth harmonics of the voltage of rectifiers 1 and 2, as well as rectifiers 3 and 4, are in phase. In this case, the sixth harmonics of rectifiers 1, 2 and rectifiers 3, 4, connected to different chokes, are in antiphase, fed into the load and compensated there.

The fundamental voltage harmonic (g = 12) and even voltage harmonics 18, 24, 30, ... of all simple rectifiers coincide in phase, are smoothed out by a filter and fed to the load.

For a twelve-phase rectifier (Fig. 2), (m = 12, m _o = 2, n = 6, k = 3, p = 2) even voltage harmonics 2, 4, 8, 10, ... rectifiers 1-3 are phase shifted at an angle of 60 ° (1 / 3Tg), fed to throttle 1; rectifiers 4-6 to choke 2 and are mutually destroyed. The sixth harmonics of the voltage of rectifiers 1-3, as well as rectifiers 4-6, are in phase. In this case, the sixth harmonics of the voltage of rectifiers 1-3 and rectifiers 4-6 connected to different chokes are in antiphase, fed into the load and compensated there.

Fundamental harmonics (g = 12) and even harmonics 18, 24, 30, ... coincide in phase, are smoothed by a filter and fed to the load.

Thus, the proposed multiphase rectifiers provide compensation in the filter chokes or in the load, as well as smoothing with an equivalent inductive - capacitive filter with an appropriate filtering coefficient of all harmonic components of the voltage of simple rectifiers.

New in the invention is the use of a multi-winding choke filter in multi-phase rectifiers with several chokes and the connection of each simple rectifier included in the multi-phase rectifier to the load through a separate choke winding.

Based on the above, it can be concluded that the proposed device allows you to obtain a positive effect.

The invention is new because when analyzing the available sources of information, no analogues with a similar set of essential features were identified.

Literature

1. Semiconductor rectifiers. Ed. F.I. Kovalev and G.P. Mostkova. M .: Energy, 1978, p. 36-118.

2. Multiphase rectifier. A.S. 547017, H2M 7/06. Shuvaev Yu.N., Vilenkin A.G.

3. Shuvaev Yu.N. New circuits of polyphase rectifiers - Questions of radio electronics. Ser. general technical, 1975, no. 1, p. 79-90.

4. Shuvaev Yu.N. Selection of the optimal circuit of a multiphase low-voltage rectifier in terms of overall, mass and energy parameters. - Questions of radio electronics. Ser. general technical, 1978, no. 3, p. 77-89.

5. Sources of secondary power supply, ed. Yu.I. Koneva - M: Radio and communication, 1983, p. 223 - 246.

6. Sources of power supply of electronic equipment: Handbook / GS. Nivelt, K.B. Mazel, Ch. I. Khusainov and others: Under. ed. G.S. Nivelt. - M: Radio and communication, 1986, p. 136-143.

7. Netushil A.V., Strakhov S.V. Fundamentals of electrical engineering, part 2, Gosenergoizdat, 1955, 211 p.

8. Bessonov L.A. Theoretical foundations of electrical engineering. M .: Higher school, 1973, p. 225-231.

9. Theoretical foundations of electrical engineering. T. 1. Foundations of the theory of linear circuits. Ed. P.A. Ionkin. M .: Higher school, 1976, p. 544.

Claims (4)

1. A polyphase rectifier containing a set of transformers, n simple rectifiers, the number of which is equal to or a multiple of two or three, connected to the total load through p independent filter chokes and an output capacitor, the number of transformers and the connection diagram of their primary and secondary windings correspond to the number of phases of the rectifier, the secondary windings are connected in a multiphase ray star, characterized in that each filter choke has k windings connected in parallel and according to, the beginning of each winding is connected to the output of a simple rectifier, and their ends are connected to the load, the number of filter chokes and the number of their windings are related by the ratio n = pk. 2. A multiphase rectifier according to claim 1, characterized in that each simple rectifier is made according to the scheme of a six-phase rectifier with a midpoint. 3. A multiphase rectifier according to claim 1, characterized in that each simple rectifier is made according to the scheme of a three-phase rectifier with a midpoint. 4. The multiphase rectifier according to claim 1, characterized in that each simple rectifier is made according to the scheme of a full-wave rectifier with a midpoint.

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