RU2222066C2 - Variable-ratio transformer with rotary magnetic field - Google Patents

Abstract

FIELD: electrical engineering, transformers with magnetization. SUBSTANCE: variable-ratio transformer has external laminated hollow cylinder with trapezoidal slots in inner surface to drop multiphase primary winding and internal laminated cylinder with trapezoidal slots in outer surface to accommodate secondary winding, magnetic shunt in the form of intermediate hollow cylinder with trapezoidal slots in outer and inner surfaces to drop magnetization winding. Primary windings of current transformers are placed correspondingly in phases A, B, C of load. Rectifiers are supplied from secondary windings f current transformers. Adjusting rheostat is meant to set output voltage. Shunt permeance is adjusted by change of current in its magnetization winding, Value of magnetization current is adjusted by automatic regulator incorporating current transformers and rectifiers which alters voltage in proportion with change of load current. Changing current in magnetization winding it is possible to alter value of magnetic flux linked with turns of secondary winding put on secondary yoke and consequently value of output voltage. EFFECT: exclusion of additional external D C power supply source needed for feeding of magnetization winding of shunt, increased stability of output voltage with rise of load current. 2 dwg

Description

 The invention relates to electrical engineering, and in particular to transformers with magnetization.

A device [1] is known, which contains a composite cylindrical lined magnetic pipe having external and internal parts with grooves for alternating current windings and a magnetizing winding. In order to expand the range of regulation of the output voltage and simplify the manufacturing technology, a magnetic shunt is inserted into it, installed between the teeth of the external and internal parts of the magnetic circuit and made in the form of a lined hollow cylinder with open grooves located on its internal and external surfaces, in which a toroidal magnetization winding is placed covering the outer and inner cylindrical surfaces of the shunt, and the pavas and teeth of the shunt are located respectively against the grooves and teeth of the outer th and inner parts of the magnetic circuit
The disadvantages of the device are
- the need for an additional regulated external DC source to power the shunt bias winding;
- decrease in output voltage with increasing load current.

The objectives of the invention are
- the exclusion of an additional external adjustable DC source necessary to power the bias magnetization winding, i.e. autonomy of an adjustable transformer;
- improving the stability of the output voltage of an adjustable transformer with an increase in its load current.

 The tasks are solved by introducing a current transformer with a rectifier into each of the three phases of the load circuit of the adjustable transformer to power the shunt magnetization winding.

The technical result is expressed in the fact that
- provides autonomy of the proposed device due to the elimination of the need for an additional external adjustable constant current source to power the magnetization winding of the jester,
- at its core, additional elements introduced into the known device [1] are an automatic output voltage stabilizer. As the results of an experimental study show, in the known device, when the load current increases from 0 to the nominal value, the output voltage decreases by 53.3%, and in the proposed device - only 1.1%.

 Figure 1 shows a cross section of a transformer with a rotating magnetic field (TWMP).

 An electrical circuit for including elements of the proposed device is shown in figure 2.

The design of the TVMP contains (see figure 1)
- primary yoke 1 - external lined hollow cylinder with trapezoidal grooves on the inner cylindrical surface for a multiphase primary winding of alternating current 2;
- secondary yoke 3 - inner lined cylinder with trapezoidal grooves on the outer cylindrical surface for a secondary multiphase winding of alternating current 4;
- magnetic shunt 5 - an intermediate hollow cylinder with trapezoidal grooves on the outer and inner cylindrical surfaces for the toroidal magnetization winding 6.

On the electrical circuit (see figure 2) the following notation:
- 7, 8, 9 - current transformers, the primary windings of which are included respectively in phase A, B, C of the TVMP load;
- 10, 11, 12 - bridge rectifiers powered from the secondary windings of the respective current transformers;
- 13 - adjustment rheostat for changing the current in the power circuit of the magnetization winding.

 The outputs of the rectifiers 10, 11, 12 (see figure 2) are connected to each other in series, which ensures the summation of their output voltages. This sum of voltages is the supply voltage of the shunt bias winding.

 The electrical circuit of the proposed device (see figure 2) provides a compound (proportional to the current load) voltage stabilization at the output of the TVMP. The output voltage required for stabilization is set using the adjustment resistor 13.

 The proposed device works as follows (see FIGS. 1, 2): when the Uvh power is connected to the primary winding of the alternating current 2, the current flows through the latter, creating a rotating magnetic flux Ф1. This magnetic flux, passing through the primary yoke 1, is divided into two components: Фя2 and Фш. The component FSh is a scattering stream and closes through a magnetic shunt 5, and the component Pha2, being the main working stream, closes through the secondary yoke 3, and, crossing the turns of the secondary winding of the alternating current 4, induces an electromotive force in it proportional to the magnitude of the flux Ф2.

The relationship of the components of the primary magnetic flux is determined by the expression
Фя1 = Фя2 + Фш, (1)
whence it follows that
Фя2 = Фя1-Фш, (2)
From the expression (2) it follows that by changing the value of Фш, it is possible to change the value of Фя2, and consequently, the value of the voltage Uout at the output of the device. The value of Фш itself depends on the magnetic resistance of the shunt, which in turn is determined by the magnitude of the current flowing through the magnetization winding 6. Regulation of the magnitude of the current in the magnetization winding 6 is provided by an automatic regulator consisting of current transformers 7, 8, 9 and rectifiers 10, 11, 12. The rheostat 13 serves to set the output voltage to be stabilized.

 So: when the load current increases in the output windings of current transformers 7, 8, 9, the alternating voltage proportionally increases. The DC voltage rectified in rectifiers 10, 11, 12 also increases. Next, the summation of these rectified voltage values is carried out, and their sum is the supply voltage of the shunt bias winding. Moreover, this voltage increases in proportion to the increase in the load current. Consequently, the bias current of the shunt will also increase in proportion to the load current. An increase in the bias current will cause a corresponding increase in the magnetic resistance of the shunt. As a result, the magnitude of the magnetic flux FSh, closed by the magnetic shunt 5, decreases. Moreover, in accordance with expression (2), the magnetic flux Фя2 increases, which closes along the secondary yoke 3 of the TWMP and, therefore, the voltage Uout at its output winding 4 remains equal to the initial one. With a decrease in current in the magnetization winding 6, all processes proceed in the reverse order.

LITERATURE
1. Copyright certificate 1070615 of the USSR, MKI H 01 F 29/14. "Adjustable transformer with a rotating magnetic field." M.M. Krasnoshapka, G.A. Kovalenko, D.M. Krasnoshapka. - publ. 01/30/84 (prototype).

 2. Copyright certificate 1179488 of the USSR, MKI N 02 K 17/30. "Adjustable induction motor" D.M. Krasnoshapka. G.A. Kovalenko, D.M. Krasnoshapka. - publ. 09/15/85.

Claims (1)

An adjustable transformer with a rotating magnetic field, comprising a composite cylindrical lined magnetic core having external and internal parts with grooves for multiphase primary and secondary windings of alternating current, as well as a magnetic shunt made in the form of a hollow cylinder with grooves for magnetization winding, characterized in that it equipped with current transformers, the primary windings of which are included in each phase of its load, and the secondary windings supply bridge rectifiers, the terminals of which are connected to each other in particular, providing a summation of their output voltages, which is the supply voltage of the magnetization winding, and the regulating rheostat provides the necessary level of the regulating voltage.

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