JPH04230010A - Transformer - Google Patents

Abstract

PURPOSE: To prevent eddy currents from being generated in a winding by a stray magnetic field in a gap, namely to reduce the heat generation of the transformer. CONSTITUTION: A ferromagnetic core 3 which is interrupted by a gap 11 and a coil former 5 equipped with a winding packet 7 are provided, and this coil former 5 surrounds the core 3 in the area of the gap 11. A winding packet 7 has a foil-winding packet 17 of conductive foil and a spacer element 15, which is positioned between the coil former 5 and the foil-winding packet 17 for reducing the generation of an eddy current by a stray magnetic field 13.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention comprises a ferromagnetic core constituting a magnetic circuit interrupted by at least one air gap, and a winding form surrounding the ferromagnetic core in the area of this air gap, the winding form being electrically conductive. The present invention relates to a transformer provided with a winding packet of magnetic foil. By conductive foil winding packet is meant here any winding packet having at least one layer of conductive foil.

0002

[Prior Art] Such a transformer is disclosed in British Patent No. GB-A.
It is described in the specification of No. 2,037,089 and is known. The presence of air gaps in the magnetic circuit creates stray magnetic fields that cause eddy currents in the windings, the strength of which increases as the air gap size increases. This British patent subdivides the air gap into partial air gaps in order to limit the lateral spread of stray magnetic fields, but the structure is complex.

0003

SUMMARY OF THE INVENTION It is an object of the invention to provide a transformer of the above-mentioned type which is simple in construction and in which stray magnetic fields do not disturb the conductive foil winding packets. be.

0004

[Means for Solving the Problems] The present invention provides at least one
A transformer comprising a ferromagnetic core constituting a magnetic circuit interrupted by two air gaps, and a former surrounding the ferromagnetic core in the region of the air gap, the former being provided with a winding packet of conductive foil. , characterized in that a number of electrically insulating spacer elements are arranged between the winding former and the winding packet.

The spacer element maintains the former and the winding packet at a relative distance, thereby preventing the formation of eddy currents in the winding packet due to stray magnetic fields. Therefore, the configuration can be considerably simplified by limiting the gap to one large gap. The present invention is based on the recognition of the fact that, in order to achieve the above-mentioned objects, no commonly used configurations are employed. In such a configuration, the transformer windings are located as close as possible to the core, so that the transformer is as compact as possible.

According to the invention, the spacer element is preferably a winding of insulating foil. The conductive foil winding packet typically occupies only a portion of the available winding space. First, insulating winding foil is loaded into the winding space that is not needed in the coil, and then the coil is wound.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a transformer 1 having a ferromagnetic core 3 constructed with two parts, for example of ferrite, forming a magnetic circuit. The transformer 1 further has a winding former 5 . This former 5, usually made of electrically insulating material, is provided with a winding packet having a primary and a secondary coil. The ferromagnetic core 3 has an air gap 11 located within the former 5 .

FIG. 2 shows a detailed cross-section of the winding form 5 and the winding packet 7 in the region of the air gap 11. A stray magnetic field is generated in the vicinity of the air gap 11, the lines of magnetic force 13 of which are shown by broken lines. Because of the air gap 11, the magnetic lines of force 13 spread widely in the lateral direction. Winding the winding directly on the former 5 therefore creates eddy currents in this winding, which increase the operating temperature of the transformer. This disadvantage can be avoided by arranging an electrically insulating spacer element 15 between the former 5 and the winding. For this purpose, the winding packet 7 comprises a packet 15 wound with insulating foil and located directly on the winding former 5, and a foil winding packet 17 with a primary and a secondary coil. The foil-wound packet 17 may be formed by wrapping layers of conductive foil, such as copper or aluminum foil, separated from each other by insulating foil. as desired,
One or more of the coils may be constructed with windings of copper wire. All coils may be formed from wrapped conductive wire, and the electrostatic shielding packets may be constructed from conductive foil.

[0009] Since the type of transformer was selected, the winding package 7
The winding space obtained for each case is constant. Generally, the foil winding packet 17 does not require the entire winding space. There is therefore space for the packet 15 to act as a spacer element between the former 5 and the foil winding packet 17. In this way, the foil winding packet 17 is kept at a distance from the winding form 5, so that the field lines 13 of the leakage field do not reach the foil winding packet 17 and the formation of eddy currents is prevented, thus transforming The operating temperature of the device decreases.

Instead of providing an insulating foil 15 on the winding form 5 to prevent eddy currents from forming in the foil winding packet 17,
The same effect can be achieved by arranging the spacer elements differently between the former 5 and the foil winding packet 17. This effect can be obtained, for example, by selecting a large diameter of the former. However, in this case the flexibility of the size of the winding space for the winding packet 7 is limited.

The results for the operating temperature as a function of the number of layers of insulating foil are shown for the following measured data. output to 200
W, and the thickness of the insulating foil is 6 μm, when there is no additional insulating foil: Temperature increase = 60°C Insulating foil is 45
When adding 0 layer: Temperature increase = 50℃ Insulating foil 650℃
When a layer is added: temperature increase = 44°C.

[Brief explanation of the drawing]

1 is a diagrammatic side view of a transformer comprising a ferromagnetic core with an air gap; FIG.

FIG. 2 is a detailed sectional view of a part of the transformer in the region of the air gap in the core;

[Explanation of symbols]

1 Transformer 3 Ferromagnetic core 5. Winding type 7 Winding packet 11 Voids 13　Magnetic field lines 15 Spacer element 17 Foil winding packet

Claims (2)

[Claims] 1. A ferromagnetic core constituting a magnetic circuit interrupted by at least one air gap, and a former surrounding the ferromagnetic core in the region of the air gap, the former comprising a winding packet of conductive foil. A transformer comprising: a plurality of electrically insulating spacer elements arranged between said winding former and said winding packet. 2. The transformer according to claim 1, wherein the spacer element is a winding of insulating foil.