RU2600571C2 - Transformer, containing three-phase and circular windings - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electrical engineering and can be used in multiphase semiconductor converters, rectifiers, inverters, reversible converters, DC voltage converters. Transformer comprises three-phase and circular windings and formed of two parts: outer and inner magnet cores containing equal odd number of semi-closed slots, multiple of three made to full height of coil groups. Said windings are arranged in slots of inner and outer magnet cores, respectively, and made as drum equal coiled double-layered, have fractional number of slots per pole and phase and shortened pitch. Magnetic axis of the three-phase winding is inclined relative to circular winding magnetic axis by one slot pitch, which provides for suppression of magnetic field higher spatial harmonic components and slot ripples, spaced apart at different magnetic cores. Windings have improved cooling conditions, thereby reducing specific consumption of materials for manufacture of transformer.

EFFECT: technical result consists in improvement of magnetization curve, higher efficiency and power factor.

1 cl, 4 dwg

Description

Area of use. The invention relates to transformer construction and can be used in multiphase semiconductor converters, in particular in rectifiers, inverters, reversible converters, DC voltage converters, etc.

The level of technology. A multiphase transformer with a rotating magnetic field is known from the prior art, comprising a middle magnetic circuit, bursted from packets of different profiles with grooves on the end, inner and side surfaces in which three-phase and multiphase windings are laid. Two extreme packages of the middle lined magnetic core have grooves to the full height of the coil group. The central part of the middle charged magnetic circuit has grooves at the outer and inner surfaces for laying winding coils therein. Additional magnetic cores are made twisted without grooves (RF Patent No. 2305339, IPC H01F 30/14, Н02М 5/14, 2007). The following factors are the disadvantages of this analogue:

- the presence of a direct open groove, due to which the tooth harmonic components with relative frequencies v _Z = kZ / p ± 1 appear in the magnetic field curve, where:

k - numbers of the natural number (1, 2, 3, ...);

Z is the number of grooves;

p is the number of pairs of winding poles;

- low utilization of electrical steel due to early saturation of the magnetic system at low values of magnetomotive force (MDS);

- tooth harmonic components have a significant amplitude (more than 1 T) and prevent the growth of the fundamental harmonic of magnetic induction, which contributes to a significant increase in the magnetizing current and a decrease in the power factor of the transformer.

The closest to the claimed invention in technical essence and the achieved result is a multiphase transformer with a rotating magnetic field, containing a middle twisted magnetic circuit with grooves on the end surfaces, in which the primary three-phase winding and two side twisted magnetic circuit with grooves on the end surfaces adjacent to the ends of the middle a twisted magnetic circuit with multiphase windings, each of which covers the side magnetic circuit in the grooves of which it is laid (RF Patent No. 2115186, IPC H01F 30 / 14, H02M 5/14, 1998). This invention is taken as a prototype.

The disadvantages of the prototype include the following:

- the use as an output multiphase multipath winding, which significantly complicates the manufacturing technology of a transformer with a rotating magnetic field, and also does not contribute to the elimination of higher harmonics due to steel saturation in the linear voltage curves;

- the use of open grooves in the outer and inner parts of the middle lined magnetic core;

- the presence of significant magnetic fluxes of scattering in connection with the winding of the windings on the cylindrical surface of the middle twisted magnetic circuit that does not have grooves on the side surface, since the grooves in the middle magnetic circuit are cut only on its end surfaces;

- the use of three-phase and circular windings with a diametrical pitch, which negatively affects the quality of the supply and output voltage;

- the use of additional side twisted magnetic cores, which significantly increases the mass, dimensions and cost of the transformer;

- relatively low values of coefficient of performance (COP) and power factor of the transformer;

- the use of windings having an integer number of grooves per pole and phase, which does not contribute to the suppression of higher harmonics of the magnetic field in the curves induced in the EMF windings;

- ineffective cooling conditions of the windings due to the lack of a channel for the passage of air between the primary and secondary windings;

- the impossibility of using the bevel of the magnetic axes of the primary winding relative to the secondary as the main means of eliminating the manifestation of tooth harmonics of the magnetic field in the phase and linear EMF curves;

- increased copper consumption due to the significant frontal parts of the windings.

The objective of the invention. The invention allows to eliminate the main disadvantages of the prototype. The new transformer with a rotating magnetic field (TWMP) surpasses the prototype in linearity of the main magnetization curve, efficiency and power factor, as well as in electromagnetic compatibility with the mains and the load. In addition, the dimensions of the magnetic circuit are reduced due to the elimination of two additional side twisted magnetic cores, while the quality of the supply and output voltage of the converter is improved due to the fabrication of a blended cylindrical magnetic circuit of the TVMP with a half-closed groove, the replacement of three-phase and circular power windings with a diametrical pitch with shortened pitch and fractional windings the number of grooves per pole and phase, this event allows you to suppress the higher spatial harmonic components of the magnetic field as well as harmonic percussion components due to the use of a fractional number of grooves per pole and phase when winding the windings, causes a decrease in the magnetic fluxes of the scattering of the frontal parts of the TVMP windings and helps to increase its installed power, increase the efficiency to 90 ... 95% and the power factor to 0.85 ... 0.90.

Disclosure of the invention. The essence of the invention lies in the fact that the TVMP magnetic circuit consists of two concentric components: a round internal magnetic circuit, in the half-closed grooves of which the circular winding is laid, and an annular external magnetic circuit, in which the three-phase winding is laid in the half-closed grooves.

The number of grooves on the external and internal magnetic circuits is chosen by the same number, a multiple of three and not even.

The external and internal magnetic circuits are joined in such a way as to ensure the location of their teeth strictly opposite to each other, since it is with such a mutual arrangement that the magnetic field curve is most closely approximated to a sinusoidal shape.

The air gap between the magnetic circuits has a constant value, determined on the basis of the requirements for the main magnetization curve of the transformer.

In half-closed grooves, grooved both on the external and internal magnetic circuits, shortened three-phase and circular windings are laid, and the number of grooves per pole and phase for three-phase and circular windings is selected fractional with a fractional denominator of two.

The magnetic axis of the circular winding coincides with the axial axis of the central symmetry of the internal magnetic circuit, and the magnetic axis of the three-phase winding is located at an angle to the axial axis of symmetry so as to obtain a bevel of the three-phase winding relative to the circular one tooth division.

As a result of the concentric arrangement of one magnetic circuit relative to another, a single magnetic system is formed in which the required air gap is formed between the charged magnetic circuits, which provides the necessary linearity of the main magnetization curve of the magnetic circuit of the entire TVMP, which allows for high efficiency and power factor, and the use of three-phase and circular windings with shortened step, the choice of the fractional number of grooves per pole and phase for three-phase and circular windings causes the suppression of higher x spatial harmonic components of the magnetic field due to the presence of the magnetic axis of inclination relative to the three-phase windings circular is suppressed tooth harmonics that are not amenable to compensation by using only a shortening coefficient distribution coefficient; the above measures improve the electromagnetic compatibility of the semiconductor converter with the mains and the load.

The proposed technical solution is new, having 7 (seven) fundamental differences from the prototype:

- to ensure the linearity of the main magnetization curve of the transformer magnetic circuit when the main rotating magnetic flux is closed, an air gap is introduced into the structure, which also suppresses higher harmonics of the magnetic field;

- to improve the electromagnetic compatibility of semiconductor converters with the mains and the load, a shortened pitch along the grooves of the three-phase and circular windings is used, and to suppress the higher spatial harmonic components of the magnetic field, a fractional number of grooves per pole and phase for the three-phase and circular windings is selected;

- for almost complete suppression of the tooth harmonics of the magnetic field, the bevel of the magnetic axis of the three-phase winding relative to the circular magnetic axis by one tooth division is used;

- three-phase and circular windings with taps are placed in the half-closed grooves of the external and internal magnetic circuits, respectively, using the general technology of the windings;

- the cooling conditions of the windings are improved due to their location on various magnetic circuits from the inside and outside;

- decreases the specific consumption of copper by reducing the length of the frontal parts of the windings;

- two additional lateral twisted magnetic cores are eliminated, due to which the overall dimensions and characteristics are improved and the specific consumption rate of materials is reduced (kg / kW).

The proposed solution has an inventive step, since the set of essential features of the device leads to a new technical result - increased efficiency, power factor and improved electromagnetic compatibility of semiconductor converters equipped with the proposed transformer, with a supply network and load due to the use of a new design of the transformer magnetic circuit, which is of two parts: internal and external, - having the same number of grooves, and also where the slot of one tooth is located willow for the closest possible approach of the magnetic field curve to a sinusoidal shape, forming a single magnetic system in which there is the required air gap, providing the necessary linearity of the main magnetization curve of the transformer magnetic circuit, which allows to obtain high efficiency and power factor of the transformer, and the use of three-phase and circular windings with in a shorter step, the choice of a fractional number of grooves per pole and phase for three-phase and circular windings causes the suppression of higher spatial armonicheskih components of the magnetic field and the tooth harmonics, thereby improving the electromagnetic compatibility of the semiconductor converter to the mains and the load is further applied bevel windings in order to eliminate higher order harmonics perforated for harmonic distortion of less than 3 ... 4% without any additional measures.

A brief description of the drawings. The invention is illustrated by drawings in the amount of 4 (four) pieces.

In FIG. 1 and FIG. Figure 2 shows a transformer with a rotating magnetic field, which contains external (pos. 1) and internal (pos. 2) magnetic cores, three-phase (pos. 3) and circular (pos. 4) two-layer drum equal to the air gap separated by a uniform air gap throughout the double pole division windings. In this case, the electric wires of the three-phase winding (pos. 3) are located in the grooves of the external magnetic circuit (pos. 1), and the circular conductors (pos. 4) are located in the grooves of the internal magnetic circuit (pos. 2). The conductors of the windings are electrically isolated from the magnetic cores (pos. 1, pos. 2) by means of interlayer (pos. 5) and slot (pos. 6) insulation. Isolated coil groups are fixed in their grooves with wedges (key 7).

In FIG. Figure 3 shows the image of the magnetic cores (pos. 1, pos. 2) of the transformer assembly in a perspective view.

In FIG. Figure 4 shows a non-sinusoidal magnetic field curve, as well as the spectrum of the EMF curve obtained with this transformer design in the presence of the introduced shortening, distribution and bevel coefficients of the windings.

The implementation of the device.

The transformer is formed of two parts: the internal lined magnetic circuit and the external lined magnetic circuit having half-closed grooves to the full height of the coil group. The windings are made by drum loose two-layer with equal pitch.

When forming a common lined magnetic circuit, the internal magnetic circuit is concentrically inserted into the external circuit while maintaining a uniform air gap throughout the double pole division.

The mutual arrangement of the magnetic cores should be ensured so that from the edges there is an exact coincidence of the slots of the teeth of the external magnetic circuit with the slots of the teeth of the internal; this transformer design allows to obtain high efficiency and power factor, the use of three-phase and circular windings with a shortened pitch, the choice of a fractional number of grooves per pole and phase for three-phase and circular windings and bevel windings relative to each other determine the suppression of higher spatial harmonic components of the magnetic field and the tooth harmonics , which improves the electromagnetic compatibility of the semiconductor converter with the mains and the load.

возбуждает в секциях круговой обмотки ЭДС индукции, сдвинутые относительно друг друга на угол 2π/n, где n - число секций круговой обмотки трансформатора. В результате происходит преобразование симметричной трехфазной системы напряжений в симметричную n-фазную систему напряжений, которая преобразуется в выпрямленное напряжение с помощью полупроводникового коммутатора, подключающего максимально близкие к диаметру отводы круговой обмотки на сборные шины в том случае, если реализовано применение трансформатора в выпрямительном агрегате.When a three-phase symmetrical voltage system is applied to a three-phase winding, it creates a rotating magnetic field in the transformer magnetic circuit, which, in accordance with the law of electromagnetic induction

excites in the sections of the circular winding EMF induction shifted relative to each other by an angle of 2π / n, where n is the number of sections of the circular winding of the transformer. As a result, a symmetric three-phase voltage system is converted into a symmetric n-phase voltage system, which is converted to rectified voltage using a semiconductor switch that connects the circular winding taps to the busbars as close as possible to the diameter if the transformer is used in the rectifier unit.

When performing internal and external magnetic circuits with a half-closed groove and windings with a shortened pitch and a fractional number of grooves per pole and phase, the magnetic field curve significantly approaches a sinusoidal shape. At the same time, the tooth harmonic components, which have the largest value compared to the fundamental harmonic, are shifted to the high-frequency part of the spectrum and decrease in amplitude by 2.5 ... 3.5 times, without causing more restriction on the growth of the fundamental harmonic of the magnetic field, which induces the fundamental harmonic of the EMF balancing externally applied three-phase voltage.

Thus, the device allows to obtain the design of a transformer having improved electromagnetic compatibility with the mains and the load. At the same time, the magnetic fluxes of scattering of the frontal parts of the primary and secondary windings are reduced, which allows to increase the installed power of the transformer, increase the efficiency and power factor, reduce the consumption of active materials: electrotechnical copper and steel, and - improve the cooling conditions of the windings when their external and internal design is implemented magnetic circuits.

Claims (1)

A transformer containing external and internal magnetic circuits, separated by a uniform air gap, with three-phase and n-phase, n-phase, double-layer windings with taps located in their half-closed grooves, respectively, characterized in that both charged magnetic circuits have half-closed coil grooves to full height groups and form a single magnetic system in which the connection between the windings is carried out by means of a rotating magnetic field created by a three-phase mended and the number of grooves in the stacked magnetic cores is chosen equal to an odd number multiple of three, the internal teeth and slots on the edges of the magnetic core of the transformer must be exactly the same as the external magnetic splined teeth.

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