RU2119205C1 - Transformer ( variants ) - Google Patents

Abstract

FIELD: electrical engineering, electrical equipment for electric power stations, substations, power lines and other electrical installations. SUBSTANCE: transformer is composed of magnetic circuit 1, primary and secondary 4 windings. Load is connected to out secondary. Primary winding includes two sections 2 and 3 wound in one direction and having same number of turns per leg of magnetic circuit 1. Both sections are connected into series circuit with finishes x1 and x2. Windings are connected with starts a1 and a 2 to power supply source. Secondary winding 4 is wound on primary winding on same leg of magnetic circuit 1. Second variant of transformer design consists in making of primary winding composed of two parts 2 and 3 wound in opposite directions and having same number of turns per one leg of magnetic circuit. Finish x1 of one section is connected to start a2 of second section in series circuit. Both sections of primary winding are individually connected with opposite ends to power supply source. As result secondary winding may have smaller number of turns as compared with primary winding and voltage tens of times higher than that of network. EFFECT: increased functional efficiency. 2 cl, 4 dwg, 2 tbl

Description

 The invention relates to the field of electrical engineering and for the main electrical equipment of power plants, substations, power lines and other electrical devices.

 Transformers - electromagnetic static converters of electrical energy, having two or more inductively coupled windings and designed to change the AC voltage. The principle of operation of the transformer is based on the phenomenon of electromagnetic induction, discovered by M. Faraday in 1831 (Sergeenkov B.N., V.M. Kiselev V.M., Akimova N.A. Electric machines. Transformers. - M.: Higher School , 1989, p. 19).

 The transformer consists of primary and secondary windings, a magnetic core, a magnetic core and a yoke of a magnetic core.

 The transformer windings are used to create a magnetic field through which the transmission of electrical energy is carried out. The transformer winding, to which electrical energy is supplied, is called primary, and the winding from which the energy is removed is called secondary.

 The magnetic core of the transformer serves to strengthen the magnetic coupling between the windings and is the structural basis for the installation and fastening of windings, bends and other parts of the transformer.

 The closest transformer - prototype is a pulsed nanosecond transformer (ed. St. USSR 1125664, CL 3 H 01 F 19/08, BI N43, 1984). It contains a magnetic circuit with the primary and secondary windings wound, the primary and secondary windings each made in the form of two sections wound together with a double wire, have the same number of turns, the input of the transformer is the beginning of the first section, the end of the first section and the beginning of the second section of the primary winding are connected to common bus, the end of the second section of the primary winding, the end of the first and the beginning of the second sections of the secondary winding are electrically connected, the output of the transformer is the end of the second section of the secondary winding ki, the beginning of the first secondary windings connected to a common bus.

The disadvantages of the known transformers are:
- multi-turn secondary windings, which nonetheless operate in a rather narrow frequency range: 50-400 Hz, high winding resistance, i.e., the need to take into account the idle speed of the transformer when calculating the number of turns of the secondary winding to obtain the necessary (specified) output voltage;
- the complexity of the designs of transformers when using all kinds of additional parts, insulation, etc. to reduce these disadvantages.

 The objective of the invention is to reduce the number of turns in the secondary winding and the ability to wind the secondary winding with a thick wire with a cross section equal to the cross section of the primary winding.

 The problem is solved by creating a transformer containing a magnetic circuit, a primary winding, a secondary winding, to the ends of which a load is connected, while the primary winding consists of two sections wound in the same direction with the same number of screws on one core of the magnetic circuit and the ends of the winding are connected to each other in a serial circuit, the beginning of the winding sections are connected to a power source, the secondary winding is wound on the primary.

 The specified technical result is also achieved by creating a transformer containing a magnetic circuit, a primary winding and a secondary winding, to the terminals of which a load is connected, while the primary winding consists of two sections wound in the opposite direction with the same number of turns on one core of the magnetic circuit connected to each other in a serial circuit with the end of the winding of the first section and the beginning of the winding of the second section, and the beginning of the winding of the first section and the end of the winding of the second section connected to the source ICU power, the secondary winding is wound on the primary winding.

The difference of the proposed transformer is as follows:
1) the primary winding consists of two sections wound on one core of the magnetic circuit;
2) both sections of the primary winding are wound in the same direction with the same number of turns;
3) the ends of the windings of both sections are interconnected in a serial circuit, and the beginning of the winding sections are connected to a power source;
The difference of the proposed transformer (option) is the winding and connecting the sections of the primary winding, namely the sections are wound in the opposite direction with the same number of turns on one core of the magnetic circuit and are connected to each other in a serial circuit by the end of the winding of the first section and the beginning of the winding of the second section , and the opposite ends are connected to a power source.

 The essence of the invention is as follows.

If the primary winding of a known transformer with an open secondary is connected to an alternating current network with voltage U ₁ , then current i ₁ = i ₀ will flow through it. The magnetomotive force of the primary winding i ₀ w _1, caused by the current i _0, creates an alternating magnetic flux Φ in the transformer magnetic circuit, which will be coupled almost completely to all turns of the primary and secondary windings.

If the secondary winding of the transformer is connected to the load resistance R, then alternating current i ₂ will flow through it. Due to the current i _{2 of the} MDS of the secondary winding, according to Lenz’s law, it is directed counter to the MDS of the primary winding and, therefore, seeks to change the flux F. the current i ₂ also appears in the winding and keeps the magnetic flux constant (Ф = const).

When the transformer is connected to the load, a current i ₂ appears in the secondary winding, a change in which causes a change in current i ₁ in the primary winding, since the primary winding is electromagnetically connected to the secondary.

If two sections of the primary winding of the proposed transformer are connected to an AC network with voltage U ₁ , then current i ₀ will flow through them. Due to the current i ₀ t, the magnetomotive force of one section of the winding i ₀ W ₁ creates an alternating magnetic flux Φ ₁ in the transformer’s magnetic circuit, similarly, the magnetomotive force i ₀ w ₂ arises in the second section of the winding, which is equal to the MDS of the first section i ₀ w ₂ , therefore in the second section of the primary winding, an alternating magnetic flux Ф ₂ going towards the magnetic flux Ф ₁ will compensate for the magnetic flux in the first section Ф ₁ . However, due to the MDS guidance, the magnetic permeability of the magnetic core changes. When the current in the network drops in half-periods, in the magnetic circuit, the magnetic permeability is restored and, as a result, an electromotive force (EMF) is induced in the primary and secondary windings, while for the duration of the half-period of the current in the primary winding, the voltage and current coincide in shape, but with phase shift from 0 to π / 4.
In the case when both windings are wound in the opposite direction with the same number of turns, but are connected to each other in a serial circuit with opposite ends - the output of the first and the input of the second section, the current in the primary winding i ₀ will also create MDF with a magnetic flux Ф ₁ - Ф ₂ = 0, i.e. it is possible to achieve the same technical result as in the case of winding both sections in the same direction. When the load R _{n is} connected to the secondary winding, the voltage form does not change. The output voltage depends on the increase in the number of turns in the secondary winding compared to the number of turns in the primary winding.

 The industrial applicability of the proposed transformer is proved as follows.

 In FIG. 1 shows an electrical diagram of a transformer according to embodiment 1; in FIG. 2 - electrical diagram of the transformer according to option 2; in FIG. Figure 3 shows the dependences of the increase in current and voltage in the primary and secondary windings in both versions of the transformer.

The primary winding of the transformer consists of two sections, therefore, to distinguish and in accordance with the concepts accepted in the art, the following notation was adopted for the sections of the primary winding:
a ₁ - the beginning of the winding and the beginning of the phase of the first section (input);
x ₁ - the end of the winding and the end of the phase of the first section (output);
a ₂ - end of the winding and the beginning of the phase of the second section (input);
x ₂ - the beginning of the winding and the end of the phase of the second section (output).

In FIG. 1 and 2 are shown:
1 - magnetic circuit;
2 - the first section of the primary winding;
3 - the second section of the primary winding;
4 - secondary winding;
a ₁ and x _{1 are the} beginning and end of the winding of the first section;
a ₂ and x ₂ - the end and beginning of the winding of the second section, while the beginning of the section corresponds to the beginning of the winding of the section on the core of the magnetic circuit, and the end of the winding of the section corresponds to the end of the winding;
A and X - the beginning and end of the phase of the secondary winding (input and output);
R _n - load resistance connected to the secondary winding.

The primary winding of two sections 2 and 3 is wound on the core of magnetic core 1, and both sections of the winding are wound in the same direction and have the same number of turns, while the second section 3 is wound on the first 2. The ends of the windings of sections x ₁ and x _{2 are} connected to each other in the serial circuit, the beginning of the winding a ₁ and a _{2 are} connected individually to the power source.

The secondary winding 4 is wound with a third layer on the primary winding 2 and 3. To the ends of the secondary winding A and X is connected the load resistance R _n .

In the case of the embodiment of the transformer, the primary winding of two sections 2 and 3 is wound on the core of magnetic core 1, and both sections are wound in the opposite direction and have the same number of turns, while the second section 3 is wound on the first 2. End of the winding of the first section x ₁ and the beginning of the winding of the second section x _{2 are} connected to each other in a serial circuit, the other ends of the sections a ₁ and a _{2 are} connected to a power source.

The secondary winding 4 is wound on the primary winding 2 and 3. To the ends of the secondary winding A and X is connected the load resistance R _n .

 The transformer operates as follows.

 Option 1.

1. Idling (without connecting the load). The ends (inputs) of two sections 2 and 3 of the primary winding a ₁ and a _{2 are} connected individually to the power source U. The other ends (conclusions) of sections 2 and 3 of the primary winding x ₁ and x _{2 are} connected to each other in a serial circuit. When connected to a power source, a current i _o will flow through both sections of the primary winding, which causes the appearance in each section of the magnetomotive force MDS equal to i ₀ w. Due to the fact that the number of turns in each winding section is the same, the MDS of both sections will be the same and equal to i ₀ w, and due to the connection between the ends of the primary winding sections in a serial circuit, the MDS of each of the primary winding sections will compensate each other. However, due to the induction of the MDS, the magnetic permeability μ of magnetic circuit 1 changes. When the current decreases in the half-period in the magnetic circuit, the magnetic permeability is restored and, as a result, an electromotive force (EMF) is induced between the connection point and the inputs in both sections of the winding (curve 1 in Fig. 3 ) Since the primary winding for the MDF remains open, therefore, an open-circuit EMF is always induced in it, i.e., the self-induction current does not occur in the winding and all the energy of the MDF is emitted as the secondary EMF. Under such conditions, in the secondary winding, the electric field per unit length of the conductor of the winding can exceed 10-100 times the electric field strength in the primary winding. As a result of these conditions, the secondary winding can have fewer turns than the primary, and the voltage is tens of times greater than the mains voltage. In this case, in the secondary winding during the half-period of the current in the primary winding, the shape repeats the voltage and current of the primary winding (curve 2 in Fig. 3).

II. Working stroke (with load connection). The load resistance R _{n is} connected to the ends of the secondary winding 4. As the current passes through the primary winding, as described above, the EMF is induced in the secondary winding (curve 3 in Fig. 3), while the voltage shape does not change, and only the voltage increases by each coil at the output of the transformer relative to the primary winding is so many times how many times the electric field in the conductor is higher than in the primary winding.

 Option 2

Idling (no load). The beginning of the winding a _{1 of the} first section 2 and the end of the winding a _{2 of the} second section 3 are connected individually to the power supply U. The other ends of the sections x ₁ x ₂ are interconnected. Since the sections are wound in the opposite direction with the same number of turns, but are connected to each other by opposite ends, when connected to a power source, the same process occurs as in the transformer according to option 1, so the technical result achieved will be similar to the transformer according to the option one.

The advantages of the proposed transformer compared to the classic transformer (prototype):
1) the number of turns in the secondary winding is reduced by 10-100 times, and therefore, the dimensions of the transformer are reduced;
2) the secondary winding can be wound with a thick wire with a cross section equal to the cross section of the primary winding wire.

 3) the secondary winding can have a number of turns both larger and smaller than in the primary winding, depending on the need for high voltage at the transformer output.

 The proposed transformer has been manufactured and has been operating for five years, creating a ten-fold increase in voltage at frequencies of 0.010-40 MHz.

 For a better understanding of the process and evidence of industrial applicability, specific examples are provided.

 Example 1. As a magnetic circuit, an annular magnetic circuit made of sheet steel and designed for a power of 2.5 kW was used. Two sections of the primary winding were wound on the core of the magnetic circuit, both sections being wound in the same direction and connected at one end in a series circuit, and the other terminals for connection to the network. A secondary winding was wound on the primary winding (the direction of winding does not affect the operation of the transformer).

 The number of turns of the primary winding is 125 in each section, the number of turns of the secondary winding is also 125, the diameter of the wound wires is the same in the primary and secondary windings and is 1.2 mm. A load is connected to the ends of the secondary winding. Voltage measurement is carried out at the input of the primary winding and the output of the secondary, i.e. on load. Schedule a) of FIG. 3.

 Example 2. As a magnetic core, ferrite rings M600NN-8 K100x60x15 were used. Two sections of the primary winding were wound on a core of a magnetic circuit assembled from four rings, and a secondary winding was wound on the primary. Moreover, both sections of the primary winding were wound in the opposite direction to each other, while the output of the first section and the input of the second, they were connected in a serial circuit, and opposite ends connected to the network. A load was connected to the ends of the secondary winding. The voltage measurement, as in the first example, is carried out at the input of the primary winding and the output of the secondary, i.e. on load. Schedule b) of FIG. 3 shows that when the magnetic circuit is made of ferromagnetic material, the shape of the voltage in the secondary winding changes.

Claims (2)

 1. A transformer containing a magnetic circuit, a primary winding and a secondary winding, to the terminals of which a load is connected, characterized in that the primary winding consists of two sections wound in the same direction with the same number of turns on one core of the magnetic circuit, the ends of the winding sections are interconnected in serial circuit, the beginning of the winding sections are connected to a power source.  2. A transformer containing a magnetic circuit, a primary winding and a secondary winding, to the terminals of which a load is connected, characterized in that the primary winding consists of two sections wound in the opposite direction with the same number of turns on one core of the magnetic circuit connected to each other in series circuit end of the winding of the first and the beginning of the winding of the second section, and the beginning of the winding of the first section and the end of the winding of the second section are connected to a power source.

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