CN104064322B - The high-efficiency high-frequency pulse transformer of low spurious electromagnetic radiation - Google Patents

Abstract

The new high-efficiency high-frequency pulse transformer with low stray electromagnetic radiation involved in the present invention improves the magnetic coupling density between the primary and secondary windings by changing the distribution mode of the windings and the flow direction of the current in the windings, and at the same time reduces the external synthetic magnetic flux. Intensity; change the mode of the traditional transformer to transmit energy to the secondary winding through the external synthetic magnetic flux of the primary winding, and use the internal synthetic magnetic flux of the primary winding to transmit energy to the secondary winding, and the external synthetic magnetic flux of the primary winding has nothing to do with the energy transmission. The magnetic flux that transmits energy is completely separated from the magnetic flux that generates electromagnetic interference, and the external synthetic magnetic flux that generates electromagnetic interference can be weakened and shielded through many technical means, which can effectively improve the transmission efficiency and power density of the transformer while greatly reducing Electromagnetic interference caused by stray radiation.

Description

New high-efficiency high-frequency pulse transformer with low stray electromagnetic radiation

technical field

The invention relates to high-frequency pulse transformer technology. In particular, it relates to a new type of high-efficiency high-frequency pulse transformer with low stray electromagnetic radiation.

Background technique

With the continuous advancement of power supply technology, the application of secondary power supplies using switching technology has penetrated into almost every field. One of the core components of switching power supplies is a high-frequency pulse transformer, and the technical bottleneck of high-frequency pulse transformers limits the progress of switching power supplies. , It is no exaggeration to say that the performance of the high-frequency pulse transformer determines the overall performance of the switching power supply. So far, traditional high-frequency pulse transformers have been difficult to meet the needs of high-efficiency and high-power conversion power supplies. The key technical bottlenecks are:

1. The power capacity of the high-frequency pulse transformer is proportional to the volume of the transformer. Under the condition of a certain volume, if you want to increase the power capacity of the transformer, you can only increase the frequency of the conversion power supply. The increase in frequency will enhance the skin effect and proximity effect of the wire, and at the same time, the loss of the magnetic core will also increase accordingly. For traditional transformers, the increase in frequency has limitations;

2. The transmission efficiency of high-frequency pulse transformer directly affects its power density. The conversion efficiency of traditional high-power high-frequency pulse transformer is difficult to break through 90%, which not only causes energy waste, increases manufacturing cost, but also limits reduced volume;

3. The energy transmission of the high-frequency pulse transformer is carried out by coupling the synthetic magnetic flux of the primary winding to the secondary winding, and this magnetic flux will also generate electromagnetic interference at the same time, that is, the magnetic flux for energy transmission and the magnetic flux that generates electromagnetic interference The flux is the same flux, the greater the transmitted power, the stronger the electromagnetic interference will be;

4. The pulse transformer transmits pulse signals with steep front and rear edges, and its high-frequency harmonics are very rich. The stray electromagnetic radiation generated while transmitting effective energy will cause strong electromagnetic interference, and with the increase of power Interference increases geometrically.

Contents of the invention

The winding of a transformer is composed of several turns of wire. When the winding is energized, a magnetic field will be generated around each wire. The strength of the magnetic field is proportional to the current, and the direction of the magnetic flux follows Ampere's law.

The windings of the traditional high-frequency pulse transformer adopt cluster winding. The magnetic flux 3-1 generated by a single wire is combined with each other to form a combined magnetic flux 3-2. The internal combined magnetic flux 3-3 between the primary winding layers of traditional cluster winding is mutually Offset does not participate in energy transmission, the external synthetic magnetic flux 3-4 transmits energy to the secondary winding through the coupling of the magnetic core; the external synthetic magnetic flux 3-4 of the primary winding that transmits energy will also generate electromagnetic interference while transmitting energy, that is Transmitting energy is the same flux as generating electromagnetic interference. Through a simple analysis, it can be seen that the fundamental reason for the low efficiency and large interference of traditional transformers is that the magnetic flux for energy transmission between the primary and secondary stages is the same as the magnetic flux for generating electromagnetic interference; and only accounts for the total number of turns of the coil A small proportion of the outer wires of the winding participate in the synthesis of this magnetic flux, while the magnetic fluxes of the vast majority of the inner wires of the winding cancel each other out and do not participate in energy transmission at all. Therefore, the energy transmission efficiency of the transformer is low, and the power density cannot be increased. What is more serious is that as the power of the transformer increases, the accompanying electromagnetic interference also increases.

The key of the present invention is to redistribute the relative position of the primary winding and the secondary winding, and control the direction of the current in the primary winding, which subverts the traditional transformer mode of transmitting energy to the secondary winding through the external synthetic magnetic flux of the primary winding, and utilizes the primary winding The interlayer magnetic flux, even the interturn magnetic flux transmits energy to the secondary winding—that is, the energy transmission of the primary and secondary windings is carried out between the internal magnetic fluxes of the windings, and the external composite magnetic flux that generates electromagnetic interference does not participate in the energy at all Transmission, the two magnetic fluxes of energy transmission and electromagnetic interference are completely separated, and while effectively improving the transmission efficiency and power density of the transformer, it greatly weakens and suppresses electromagnetic interference.

The primary winding of the transformer is made into single-layer planar coils 1-1, 1-2, ... 1-n, and the secondary winding is made into single-layer planar coils 2-1, 2-2, 2-(n-1) , a single-layer planar secondary winding is embedded between two single-layer planar primary windings, and the topmost and bottommost layers of the combined winding assembly are both primary windings; the wiring of the primary windings is controlled so that two adjacent layers of primary The current of the winding is reversed, which can ensure that the internal composite magnetic flux 3-3 between the layers of the primary winding strengthens each other, and the external composite magnetic flux 3-2 between the layers cancels each other; because the secondary winding is distributed between the primary winding layers and the primary winding For strong coupling, the windings use the interlayer internal magnetic flux 3-3 to transmit energy, and the external magnetic flux 3-2 has nothing to do with energy transmission. Although the external magnetic fluxes between the primary winding layers cancel each other out, because the external synthetic magnetic fluxes of the topmost and bottommost coils of the primary winding reinforce each other, the external synthetic magnetic flux of the primary winding is generated, which does not participate in the energy transmission, only Electromagnetic interference will be generated. By embedding shielding layers at the top and bottom of the winding assembly respectively, the external synthetic magnetic flux of the top and bottom coils can be shielded, which can more effectively suppress the electromagnetic interference that has been greatly weakened; shielding The shielding layer is designed with insulating gaps to prevent closed eddy currents; the shielding layer is designed with electrical connection terminals, which are grounded or suspended according to specific conditions in actual applications.

Also can adopt coaxial wire to make high-frequency pulse transformer, the inner conductor 5-1 of coaxial wire is the primary winding of transformer, and outer conductor 5-2 is the secondary winding of transformer, and the parallel distribution between wires; Control the wiring of primary winding, Make the currents of adjacent wires reverse phase, which can ensure that the internal synthetic magnetic flux 4-2 between the wires strengthens each other, and the external magnetic flux cancels each other; because the secondary winding is coaxially distributed outside the primary winding and strongly coupled with the primary winding, the use of the wire The internal synthetic magnetic flux 4-2 transmits energy, and the external magnetic flux has nothing to do with energy transmission and cancels each other out. Embedding the shielding layer 5-3 between the layers of the winding assembly can more effectively suppress the greatly weakened electromagnetic interference; the shielding layer is designed with insulation gaps 5-4 to prevent closed eddy currents; the shielding layer is designed with electrical connection terminals. In application, it should be grounded or suspended according to the specific situation.

Description of drawings

Figure 1: Schematic diagram of the structure

1-1——primary planar winding 1;

1-2——primary planar winding 2;

1-3——primary winding current direction;

2-1——Secondary planar winding 1.

Figure 2: Schematic diagram of primary coil current direction

Figure 3: Schematic diagram of the primary winding structure and magnetic flux of a traditional transformer

3-1——Single-turn wire magnetic flux;

3-2——External composite magnetic flux between winding layers;

3-4——The winding assembly synthesizes the magnetic flux.

Figure 4: Schematic diagram of the magnetic flux of the interlayer current inverting winding

3-3——Synthetic magnetic flux between the layers of the primary winding.

Figure 5: Schematic diagram of the magnetic flux of an inter-turn current inverting winding

4-1——Single wire magnetic flux;

4-2——Synthetic magnetic flux between wires.

Figure 6: Schematic diagram of magnetic flux with coaxial wire structure and primary winding inter-turn current reversal

5-1——coaxial wire inner conductor——primary winding;

5-2——Coaxial wire outer conductor——Secondary winding;

Figure 7: Schematic diagram of the structure of a high-frequency pulse transformer with primary and secondary windings as coaxial wires

Figure 8: Schematic diagram of the radial cross-section of a cylindrical structure coaxial wire high-power high-frequency pulse transformer with a shielding layer

5-3——interlayer shielding layer;

5-4——The insulation gap of the shielding layer.

detailed description

Embodiment 1 : Primary winding interlayer current inversion planar high-frequency pulse transformer.

Using the manufacturing process of planar transformer, the primary winding and secondary winding are divided into multi-layer production, and the number of layers of the secondary winding is one layer less than the number of layers of the secondary winding (that is, the number of layers of the secondary winding is N, then the primary winding The number of layers is N-1), a secondary winding layer is embedded between two primary winding layers, and the topmost and bottommost layers are both primary windings.

The interlayer wiring of the primary winding is connected according to the principle that the current of the primary winding layer adjacent to the secondary winding layer is in reverse phase, so as to ensure that the interlayer magnetic flux inside the primary winding is mutually enhanced in the secondary winding plane. At this time, the magnetic flux between the outer layers of the primary winding cancels each other, only the outer magnetic flux of the topmost layer and the outer magnetic flux of the bottom layer are mutually enhanced, this part of the magnetic flux does not participate in energy conversion, and only produces stray radiation, which should be done as much as possible may be reduced, so that the single-sided cross-section of the primary winding is as close to a circle or a rectangle as possible.

The secondary winding can be connected in various ways, and the connection method of the secondary winding can be set according to the requirements of the output voltage and output power.

Embodiment 2 : a high-power high-frequency pulse transformer in which the primary and secondary windings are coaxial wires and the inter-turn current of the primary winding is reversed.

The use of coaxial wires to make high-power high-frequency pulse transformers uses the core wires of the coaxial wires as the primary winding of the transformer, and the outer conductor of the coaxial wires as the secondary winding of the transformer. The current inversion of the adjacent wires can make full use of the inter-turn magnetic flux enhancement performance of the primary winding, and maximize the efficiency of energy transmission between the primary and secondary stages.

At this time, the inter-turn magnetic flux inside the primary winding strengthens each other, and the external synthetic magnetic flux cancels each other to almost zero, and its stray radiation is almost zero, so the electromagnetic interference can be minimized.

Embodiment 3 : An ultra-low EMI high-power high-frequency pulse transformer in which the cylindrical primary and secondary windings are coaxial wires and the inter-turn current of the primary winding is reversed.

Coaxial wires are used to make high-power high-frequency pulse transformers, and its structure is cylindrical—the radial section of the coaxial wires is circular, and the layers of the windings are embedded with shielding layers, and the shielding layers are opened in the axial direction. There is a gap to prevent the induced current of the shielding layer from forming a circulating current. There is a wire connected to one end of the shielding layer, which is used for grounding during application.

Use the core wire of the coaxial wire as the primary winding of the transformer, use the outer conductor of the coaxial wire as the secondary winding of the transformer, and adopt a suitable wiring method to ensure that the currents of adjacent wires in the primary winding are reversed, so that the primary winding can be fully utilized The inter-turn flux mutual enhancement performance maximizes the efficiency of energy transfer between primary and secondary stages.

At this time, the inter-turn magnetic flux inside the primary winding strengthens each other, and the combined magnetic flux outside the cylindrical radial direction cancels each other almost to zero. In addition, the role of the shielding layer ensures that its stray radiation is almost zero, and the electromagnetic interference is therefore minimized.

Claims (6)

1. A high-efficiency new high-frequency pulse transformer with low stray electromagnetic radiation; its characteristics are: a single-layer primary winding of a planar transformer is embedded with a single-layer winding between layers; the primary and secondary windings of a coaxial structure transformer are coaxially distributed; Control the current direction in the primary winding; make full use of the magnetic flux generated by each layer of the primary winding of the planar transformer or each turn of the primary winding of the coaxial transformer to transmit energy to the secondary winding; effectively improve the transmission efficiency and power density of the transformer At the same time, it greatly reduces the electromagnetic radiation caused by the stray radiation of the external magnetic flux of the transformer; the embedded shielding layer of the coaxial structure transformer can more effectively reduce the electromagnetic radiation generated by the residual external synthetic magnetic flux; among them, the single layer of the planar transformer A single-level winding is embedded between the primary winding layers, the primary winding and the secondary winding are divided into multiple layers, and the number of layers of the secondary winding is one layer less than that of the primary winding, and it is embedded between the two primary winding layers The primary winding layer, the topmost layer and the bottom layer are both primary windings, and the interlayer wiring of the primary winding is connected according to the principle that the current of the primary winding layer adjacent to the secondary winding layer is reversed; the primary and secondary windings of the coaxial structure transformer are coaxial distribution, the inner conductor 5-1 of the coaxial wire is the primary winding of the transformer, and the outer conductor 5-2 is the secondary winding of the transformer, and the wires are distributed in parallel to control the wiring of the primary winding so that the currents of adjacent wires are reversed. 2. According to the high-efficiency novel high-frequency pulse transformer of low stray electromagnetic radiation according to claim 1, the primary and secondary windings of planar transformers have remarkable characteristics; It is characterized in that: in the primary winding 1-1 of single layer and the single layer A single-layer secondary winding 2-1 is embedded between the layers of the primary winding 1-2, and the number of layers of the primary winding is one more than that of the secondary winding. When stacked, the topmost layer and the bottommost layer of the coil assembly are both primary windings. 3. According to the high-efficiency novel high-frequency pulse transformer of low stray electromagnetic radiation according to claim 1, the primary and secondary windings of the coaxial structure transformer are coaxially distributed; it is characterized in that: the inner conductor of the coaxial wire is the primary winding 5 -1, the outer conductor is the secondary winding 5-2, and the distribution of the transformer windings is in a 3D three-dimensional structure. 4. According to the high-efficiency novel high-frequency pulse transformer of low stray electromagnetic radiation according to claim 1, the current direction in the control winding has remarkable characteristics; it is characterized in that: the planar transformer structure of the secondary winding layer embedded between the primary winding layers , the interlayer current of the primary winding is reversed 1-3; when the coaxial structure transformer is used, the adjacent inner conductor current is reversed. 5. According to the high-efficiency novel high-frequency pulse transformer of low stray electromagnetic radiation according to claim 1, the planar transformer utilizes the interlayer synthetic magnetic flux of the primary winding to transmit energy to the secondary winding; it is characterized in that: each of the primary windings The magnetic flux 3-1 generated by the turn wire, after the interlayer current reverses, the interlayer composite magnetic flux 3-3 of the primary winding is the mutual enhancement of the two layers of magnetic flux; the external composite magnetic flux 3-2 between the layers cancels each other and attenuation. 6. According to claim 1, the novel high-efficiency high-frequency pulse transformer with low stray electromagnetic radiation has an embedded shielding layer; its feature is that the coaxial structure transformer is embedded with the shielding layer 5-3 coaxially.