SU930542A1 - Dc-to-ac converter - Google Patents

Description

(S) DC CONVERTER TO AC VARIABLE

I

The invention relates to electrical engineering, in particular to converter technology, and can be used in measurement and control systems as a large-scale direct current sensor.

DC-to-AC converters are known, containing an auto-oscillator on transistors and a saturable transformer, into the core window of which the power biasing cable with the measured current r is passed.

However, these converters require breaking the cable with a measured current to introduce a transformer into the window and induce interference with a wide variable spectrum in the EMF circuit, which is not always permissible and therefore limits the scope of their use.

The closest in technical essence to the proposed is a converter containing autogen

a rator with a saturable transformer and an open open magnetic circuit adjacent to it, through which the power cable with the measured current G2 is passed through.

The disadvantages of the known converter are the guidance of the EMF interference with a wide variable spectrum in the circuit of the measured current, the instability of the initial frequency of the converter and.

10 relative complexity. The induction of a measured EMF current in the circuit is caused by the fact that an open magnetic circuit with an adjacent transformer core forms

An IS is a closed loop system with varying magnetic flux, inside of which a cable is passed, representing one turn for the system. The instability of the initial frequency of the transducers is due to the fact that the magnetic resistance of an open magnetic circuit for a variable component of the magnetic flux depends on its position relative to the core (for example, on the gap between them) and on the parameters of the magnetic circuit (for example, magnetic permeability). The complexity and the increase in the mass of the transducer are due to the need for an W-shaped core for the output transformer. The purpose of the invention is to eliminate the induction of EMF interference in the measured current circuit, increase the stability of the initial frequency of the converter, reduce its mass and cost. The goal is achieved by the fact that the open magnetic circuit (: is filled with a short-circuited screen of electrically conductive material, and the saturating transformer is made toroidal. In addition, the open magnetic circuit is located in such a way that it is adjacent to the core of the saturation of the transformer from the inner side. Figure 2 shows the arrangement of the structural elements of the converter (top view from the open magnetic circuit) and a view of the design of the magnetic system of the converter on the side. The converter contains the cores 1 of the output saturable transformer, the open magnetic circuit 2 adjacent to the core 1 and A short-circuited screen (coil 3 of electrically conductive material (for example, copper)., power cable {With measured current, output winding 5, primary collector windings 6 , 7, positive feedback windings B, E, switching transistors 10, 11 and the elements of starting the converter 12, 13. The converter pa6oT et follows. When the power source is turned on and there is no current in the cable k, the converter is energized with an initial frequency determined by the supply voltage and the parameters of the saturable output toroidal transformer 1: the voltage of the converter power supply; the number of turns of the primary windings 6 and 7 of the core 1 of the output transformer; induction of core saturation 1, the magnitude of the initial frequency does not depend on the parameters and location relative to core 1 of magnetic circuit 2, since the latter is shielded by a short-circuited coil 3 and its magnetic resistance for a variable component of the magnetic flux is much greater than the magnetic resistance of the core 1. Because core 1, then the spatial flow does not form a closed loop around the cable 1 with the measured current and, therefore, does not cause in the cable 1 EMF interference with that change is magnetic; -o flow. When a constant measured current flows through the cable k, the latter induces a magnetic flux Fd in the open magnetic circuit 2, which is divided in core 1 in half and summed with the magnetic flux included in this primary period of the primary winding 6, or 7. As the measured current increases, the magnetic flux flux Fd and saturation of the core 1 is achieved faster, i.e. The frequency of the converter's inverter increases in proportion to the J ep immohme on the linear portion of the magnetization curve of the core .1. To increase the linearity of the converter, the Tokfrektoder frequency can be equipped with core 1 with partial gaps on both sides of the cable. 2i The location of the magnetic circuit 2 with the core 1 touching on the inner side stabilizes the position of the magnetic circuit 2 by partially fixing it with the core. This increases the accuracy of measurements, or simplifies the device for fixing the magnetic circuit. The technical and economic effect provided by the converter consists in eliminating the EMF interference with a wide variable spectrum in the circuit of the measured current in eliminating the influence of the parameters and position of the open magnetic circuit on the value of the initial frequency of the converter. The use of a toroidal core together W-shaped reduces the mass of the converter core and its cost. claims 1. A constant-to-ac converter that contains an

Claims (2)

Claim 1. The constant gok to variable converter containing av6 2. A converter according to claim T, characterized in that the open magnetic circuit is adjacent to the core of a saturable transformer from the inside. a generator with a saturable transformer and an open magnetic circuit adjacent to it, through the window of which a power cable with a measured current is passed, which differs in order to eliminate EMF interference in the circuit, which increases the frequency stability of the converter, so that the initial open magnetic circuit is induced by · A mouth-closed screen of electrically conductive material, and a saturable transformer is made toroidal.