JPH01283911A - Power transformer - Google Patents

Abstract

PURPOSE:To ensure offset of penetrating magnetic flux with third harmonic wave current, by winding superconductors at the upper and the lower parts of an iron core having three legs in a three-phase transformer, or mounting the superconductors in a planar pattern. CONSTITUTION:Third harmonic waves are outputted from an iron core 1. A superconductor 2 is formed in one turn. The superconductors 1 are mounted on the surrounding part of the upper and the lower parts of the iron core 1. Or the superconductor is mounted on one part. Or the outgoing parts of the harmonic waves are covered with superconductive flat plates 6 and 7. When magnetic flux is going to pass through the superconductors 2, induced electromotive forces are generated and currents are made to flow. Thus, offsetting magnetic flux is generated. It is necessary to provide a conductor having the number of turns or the cross sectional area which is equal to ampere turns forming said magnetic flux in order to make the outgoing magnetic flux zero. When this is performed with the superconductor, the magnetic flux can be offset with the thin conductor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to inverters and rectifiers containing third harmonic current [applied to source transformers].

[Conventional technology]

For example, Figure 2 is published by Denki Shoin [Transformer Design and Construction Method 12]
In Figure 0, which shows a power transformer with a three-phase iron core structure shown on page 39 and page 123 of "Electrical Introduction" published by Maruzen, there are U-phase coils (4) on each of the three legs of the core. , a V-phase coil (6), and a W-phase coil (3).
Magnetic fluxes with a phase difference of a and d) are generated, and their algebraic sum is zero. Therefore, the magnetic flux does not go out of the iron core, and the current flowing to each phase as a load current is also 2π/3 (
The ampere turns of each phase are canceled due to the phase difference of rad), and the resulting magnetic flux does not exit the iron core. However, when used as a power source for an inverter or rectifier, current containing third harmonics may flow, and in such cases, the magnetic fluxes -A, φB, and -〇 of each phase core are in phase, so they cancel each other out. It comes out outside the iron core, that is, at the top and bottom. Such magnetic flux affects external equipment, causing problems such as overheating of conductors due to eddy currents caused by changes in magnetic flux.

A current including such a third harmonic is generated due to the saturation characteristics of the iron core both in a commercial frequency power supply and in an inrush current when the power is turned on.

[Problem to be solved by the invention]

In addition, the magnetic flux that goes out causes noise in electronic circuits such as electronic devices installed near the transformer, causing malfunctions.

Due to the conventional Wl power transformer three-legged structure as shown below, the third
There were problems such as the magnetic flux caused by harmonic currents flowing outside the core, causing overheating of conductors and malfunction of electronic equipment.

This invention was made to solve the above-mentioned problems, and an object thereof is to prevent the magnetic flux generated within the iron core from flowing out of the iron core even if a current having F@3 harmonics is generated.

[Means to solve the problem]

In this invention, one turn of a superconductor is formed around the area where the third harmonic goes out from the iron core, and one turn is attached to the top and bottom or one side of the iron core, or the part where the third harmonic goes out is covered with a superconducting flat plate. .

[Effect]

Since the superconductor in this invention intersects with the outgoing magnetic flux, it generates superpower to cancel it, and the current due to the superm force cancels out the outgoing magnetic flux, so no magnetic flux exits to the outside.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, there are U-phase coils (4) on each of the three legs of the iron core.
A V-phase coil +5) and a W-phase coil (3) are wound. When the third harmonic current flows through each of these coils, it becomes the same phase as explained in FIG. 2 and goes out to the outside. Here, in the present invention, the superconductor (2) is wound all around the top and bottom of the iron core (1). In such a structure, the superconductor (2
) When a magnetic flux tries to pass through it, it generates an induced electric power, which causes a current to flow and cancel out the magnetic flux. This kind of action occurs in the same way with normal conductors, but since the electrical resistance of superconductors is zero, the effect is greater and there is no loss.In addition, in order to reduce the outgoing magnetic flux to zero, it is necessary to create a superconductor. A conductor with the number of turns or conductor cross-sectional area equal to the number of ampere turns is required, but if this is done with a superconductor, it can be done with a thin conductor, compact and! Since the electrical resistance is zero, it is possible to achieve a large effect of applying magnetic flux.

Fig. 3 shows another embodiment of the present invention, and similarly to Fig. II)i1, a U-phase coil (4), a V-phase coil (5), and a W-phase coil (3) are installed on each leg of the iron core (1), respectively. The winding is the same, but superconductor flat plates (6) are attached above and below the iron core +1). The function of the flat plate (6) is the same as that of the superconductor (2) explained in FIG.

〔Effect of the invention〕

As described above, according to the present invention, the superconductor is wound or attached in a flat plate shape to the upper and lower parts of the iron core of the three legs of the three-phase transformer, so that the magnetic flux that attempts to penetrate by the third harmonic current is canceled out. It is characterized by being able to perform its functions compactly and reliably.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a power transformer according to an embodiment of the present invention. Figure 2 is a front view of a conventional transformer. FIG. 3 is a perspective view of a power transformer according to another embodiment of the invention. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A power transformer characterized in that the whole or one of the upper and lower parts of the main landing gear core is covered with a superconductor at right angles to the direction of magnetic flux passing through the main landing gear core. (2) The power transformer according to claim 1, wherein the superconductor covering the core legs has a ring-like or plate-like shape.