FR2827073A1 - Industrial networks/information/remote control exchange transformer having two windings producing opposite fields/same intensity optimizing magnetic circuit/suppressing alternating currents with capacitive/short circuit windings. - Google Patents

Abstract

The transformer has two windings (A,B) providing opposite fields of the same intensity. The magnetic circuit is optimized by suppressing the alternating components in opposite windings (B,Sb) with a capacitor or a short circuit.

Description

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The present invention relates to an electrical transformer with compensated flux, which can receive, simultaneously and without drawbacks, direct and alternating current voltages.

If a direct current voltage is applied to the receiver winding (called primary) of a traditional electrical transformer (assuming that this winding is able to support, without excessively heating, the current which results), the said direct current generates an unproductive flux in the magnetic circuit, proportional to the ampere-turns product of the primary winding. Part of the magnetic field is thus occupied unnecessarily, at the expense of the available capacity of the magnetic circuit to ensure the transmission of alternating current, by induction, between primary and secondary.

Certain applications, industrial or otherwise, could benefit from the performance of the transformer which is the subject of the present invention.

By way of example, I signal the transmission of signals over industrial networks, for the exchange of information, controls or remote controls, between the transmitter (for example a power plant) and the receiver (for example a station equipped with a Electric transformer).

In another field, that of audio amplifiers with tubes or transistors, a direct current, called anodic, constantly flows through the power tubes or transistors, as well as the output transformer, the secondary of which is connected to the loudspeaker.

The magnetic field produced in the core of the transformer by this direct current sometimes occupying a considerable part of its capacity to transfer the corresponding alternating current from the signal, obliges to

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 provide magnetic circuits with a large section of iron, therefore more expensive.

In the transformer object of the present invention, the direct current which reaches it, is distributed on windings, antagonistic, with the result of reducing the flux to zero.

Under these conditions, the transformer core is completely free for the variable magnetic fields produced by the alternating current at the terminals of the windings.

The invention will be better understood from the description which follows, made with reference to the attached drawing by way of indicative example only, relating to a current line supplying direct current and alternating current, at the same time, to the transformer. (T).

The terminal (Y) is connected to the terminal (E) of the winding (B) of the transformer (T).

The terminal (W) of the winding (B) is connected to the terminal (N) of the winding (A) and the terminal (S) of the latter winding is connected to the terminal (X) of the current line electric.

In this way, the compound current (direct + alternating) will pass through the two windings (B) and (A), from point (Y) to point (X).

The windings (A) and (B) are constructed in the same way and are identical, either by the number of turns, or by their ohmic resistance. The winding (B) shown in FIG. 1, is on the same magnetic circuit of the winding (A).

While being identical to (A), this winding (B), is arranged in such a way that the anode current which crosses it creates, in the magnetic circuit, a field of intensity equivalent to that

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 produced by (A), but antagonistic.

It follows that the DC component, applied to the terminals (X) and (Y), will produce, in the magnetic circuit of the transformer (T) two fluxes which will cancel each other out, leaving the field free for the transmission of the current. alternative.

This point acquired, the behavior of the transformer (T) in alternating current is described below.

Fig. 1 indicates the presence of the capacitor (Cs).

Without the latter, even the alternating current components would cancel each other out (since the two windings (A) and (B) are in phase opposition) and no signal could be induced in (Sa) and, consequently, to the user device or device (UTI.).

This capacitor (Cs), of adequate capacity, short-circuits the alternating current components present at the terminals of the winding (B), by eliminating them.

The arrow (Cct), in Fig. 1 indicates the secondary short-circuit condition (Sb), which also contributes to the erasure of the alternative components present in (B).

Once this latter condition has been reached, the flux in the entire magnetic circuit is close to zero, in accordance with the law of continuity. However if the inductive coupling between (A) and (Sa) is sufficiently tight and that between (A) and (B) is not, the transmission of almost all of the power available between the primary (A) and his secondary (Sa) (minus any losses) is insured.

Measurements and tests have shown that the losses (if the

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 construction of the transformer is neat), are negligible.

This result can be explained by referring to the law of magnetic flux continuity and that of ampere-turns.

In practice, one will be able to use, on the one hand smaller transformers, for the same power and, on the other hand, send, if necessary for certain applications, direct current on the industrial AC networks, by exploiting the fact that this direct current can be, if necessary, eliminated at destination.

Claims (1)

1) Electric transformer which can be supplied, in addition to alternating current, with a direct current component, characterized in that it comprises windings, (A) and (B), by way of example only, dimensioned and arranged so as to create antagonistic fields of the same intensity, in the magnetic circuit of the transformer (T), the reduced flux resulting therefrom leaving all the capacity of the magnetic core available for working in alternating current and characterized by the suppression of the alternating component in the opposing winding (s) (B), (Sb), either with a capacitor (Cs), or with a short circuit (Cct), or with both.