RU2290739C1 - Power supply for single-phase inductive-resistive loads affording balance of three-phase primary network - Google Patents

Abstract

FIELD: electrical engineering and transformer building.

SUBSTANCE: proposed power supply designed to convert three-phase voltages and currents has magnetic circuit assembled of three cores A, B, and C of equal cross-sectional area, three-phase primary winding, sectionalizing switch, three-phase network, and secondary winding; each magnetic core mounts two partial windings having unequal turn number; winding parts on each magnetic core bearing same index have same turn number: Wa1x1 = Wb1y1 = Wc1z1 and Wa2x2 = Wb2y2 = Wc2x2; secondary winding parts are connected in series as follows: winding Wa1x1 is connected to Wb1y1 and Wc1z1 so that lead x1 is coupled with lead b1 and lead y1, with lead c1; winding Wa2x2 is connected to windings Wb2y2 and Wc2z2, lead a2i being connected to lead b2, lead y2, to lead c2, and lead a1, to leads c1 and z2.

EFFECT: simplified design, enhanced performance characteristics.

3 cl, 1 dwg

Description

The invention relates to electrical engineering, in particular to transformer building, and is intended to convert electrical energy of three-phase voltages and currents.

Known transformer converters of electrical energy of three-phase sinusoidal voltages and currents into two-phase, containing a spatial three-core magnetic circuit with a three-phase input and two-phase output windings located on it (USSR Author's Certificate No. 5998197, 10/11/1976, class N 02 M 5/14) [1] , (French Patent No. 2648612, 06/15/1989, CL H 01 F 33/00) [2].

.The disadvantages of such converters are the inability to control the output voltage, as well as a strictly fixed ratio of the number of turns of sections of the two-phase winding: in [1] it is cos15 °: cos45 °: cos75 °, and in [2] -

.

Closest to the proposed device is a transformer converter of three-phase voltage and current into two-phase, containing a magnetic circuit consisting of at least three cores A, B, C of the same cross section, a three-phase winding consisting of at least three identical with the number turns W _{t of} phases A, B, C located on the respective cores of the magnetic circuit, interconnected in a star or triangle and connected to a three-phase network, and a two-phase winding connected to a two-phase network and, characterized in that the two-phase winding is made up of several series-connected groups 1, 2, 3, n ... N, the number of which is equal to the number N of control stages, each group, in turn, consists of at least six sections: two W _ad and W _aq located on core A, two W _bd and W _bq located on core B, and two W _cd and W _cq located on core C, sections W _ad and W _{bd are} connected in series with each other and successively counter to the section W _cd and form a semigroup of the first phase D of the two-phase winding, sections W _bq and W _{c q are} connected in series according to each other and sequentially counter to the section W _aq and form a semigroup of the second phase Q of the two-phase winding, while in any group of six sections, the number of turns of sections should be related to each other as

moreover, K = W _cq / W _aq can vary arbitrarily within

(см RU 2255411, Н 02 М 5/14, 27.06.2005.)

(see RU 2255411, N 02 M 5/14, 06/27/2005.)

The disadvantage of this device is its significant complexity associated with the need for accurate selection of turns of sections according to the ratio, as well as the loss of electricity associated with a change in load, since voltage regulation occurs in the secondary circuit of the transformer.

The technical result of the proposed device is to simplify and improve technical and economic characteristics.

For this purpose, a power device for single-phase induction-resistive loads is proposed, providing symmetry of the primary three-phase network, containing a magnetic circuit consisting of three cores A, B, C of the same cross section, a primary three-phase winding, consisting of at least three identical sectioned windings located on the respective cores of the magnetic circuit, interconnected into a star, the sectional conclusions of which are connected through a sectional switch to a three-phase network, and the secondary a winding made in such a way that two partial windings with an unequal number of turns are placed on each core of the magnetic circuit, and the partial windings of each core of the magnetic circuit with the same indices have an equal number of turns: Wa1x1 = Wb1y1 = Wc1z1, and Wa2x2 = Wb2y2 = Wc2z2, and partial the windings of the secondary winding are connected in series as follows: the winding Wa1x1 is connected to the windings Wb1y1 and Wc1z1 so that the output x1 is connected to the output b1, and the output y1 to the output c1, the winding Wa2x2 is connected to the windings Wb2y2 and Wc2z2, while the output a2 is connected to the output b2, and terminal y2 is connected to terminal c2, and terminal a1 is connected to terminal x2, while a single-phase load is connected to terminals c1 and z2.

Additional differences are that capacitors are provided that are installed: one in parallel with one of the partially connected partial windings of the secondary winding of the transformer, and the other in series with a single-phase load, and also that a choke is introduced that is connected in parallel to the other series-connected partial windings of the secondary transformer windings.

The drawing shows a structural electrical diagram of the device.

The power device for single-phase induction-resistive loads, providing symmetry of the primary three-phase network, contains: a section switch 1, a primary three-phase winding 2, a secondary winding 3, a first capacitor 4, a second capacitor 5, a load 6 and a reactor 7.

A power device for single-phase induction-resistive loads, providing symmetry of the primary three-phase network, operates as follows.

When a purely active load is connected, the single-phase current In flowing in the load coincides with the interfacial voltage Ul. When connecting a load having an inductive component, the load current In and voltage Ul do not coincide in phase.

To exclude a possible shift and increase the efficiency of the power source, capacitors are provided in the device, which are installed: the first 4 in parallel with one of the series-connected partial phase windings of the transformer, and the second 5 in series with the induction resistive load.

A single-phase induction resistive load is connected to the phase terminals c1 and z2 through the second capacitor 5. Between the common point of the phase windings z2 and the phase output x2, the first capacitor 4 is connected.

When the proposed power device is connected to a three-phase network with voltages Ua, Uv, Uc, in each winding Wa, Wв, Wc, currents Ia, Iв, Ic appear, equal in magnitude, and magnetizing forces Fa, Fв, Fc appear in each core of the magnetic circuit, equal from the condition: the same number of turns is used in the windings Wa = Wв = Wc and equal currents flow through them: Ia = Iв = Ic.

The magnetic fluxes flowing in the magnetic circuit indicate voltage Uph1 and Uph2 in the two-phase windings. The voltage values correspond to the number of turns in the windings.

When the load is connected in the two-phase windings, currents Iph1 and Iph2 arise. Magnetic forces Fa, Fv, Fc appear in the cores of the magnetic circuit, the magnitude of which depends on the currents (If1 = If2) and the number of turns in the winding sections located on each core of the magnetic circuit, which is controlled by the section switch 1. Equal values of the magnetizing forces Fa = Fв = Fc result in a uniform distribution of the effect of load 6 on the three phases of the primary network and the three-phase system remains symmetrical. The inductor 7 allows you to increase the efficiency of the device.

Claims (3)

1. A power device for single-phase induction-resistive loads, providing symmetry of the primary three-phase network, containing a magnetic circuit consisting of three cores A, B, C of the same cross section, a primary three-phase winding, consisting of at least three identical sectioned windings located on the corresponding cores of the magnetic circuit, interconnected into a star, the sectional conclusions of which are connected through a sectional switch to a three-phase network and a secondary winding made by Thus, on each core of the magnetic circuit there are two partial windings with an unequal number of turns, and the partial windings of each core of the magnetic circuit with the same indices have an equal number of turns: Wa1x1 = Wb1y1 = Wc1z1, and Wa2x2 = Wb2y2 = Wc2z2, and the partial windings of the secondary winding connected in series as follows: the winding Wa1x1 is connected to the windings Wb1y1 and Wc1z1 so that the output x1 is connected to the output b1, and the output y1 to the output c1, the winding Wa2x2 is connected to the windings Wb2y2 and Wc2z2, while the output a2 is connected to the output b2, the output y2 is connected to pin c2, and pin a1 is connected to pin x2, while a single-phase load is connected to pins c1 and z2. 2. The device according to claim 1, characterized in that there are capacitors that are installed: the first in parallel with one of the partially connected partial windings of the secondary winding of the transformer, and the second in series with a single-phase load. 3. The device according to claim 1, characterized in that the throttle is introduced, connected in parallel with other series-connected partial windings of the secondary winding of the transformer.