CN202210451U - Common mode inductor - Google Patents

Abstract

The utility model provides a common mode inductor, which comprises a magnetic core, a first layer of inductance coil is uniformly wrapped on the surface of the magnetic core along the periphery, and at least one layer of inductance coil arranged sectionally at intervals are wrapped outside the first layer of inductance coil. A contrast test shows that the common mode inductor provided by the utility model can reduce distributed capacitance, increase the insertion loss, and enable the EMC (Electro Magnetic Compatibility) of a complete machine to conform to or even surpass the national standard. The common mode inductor simultaneously reduces the turn-to-turn voltage difference, effectively prevents turn-to-turn short circuits, has a simple structure, and is easy to process and produce.

Description

Common mode inductance

Technical field

The utility model relates to common mode inductance.

Background technology

The production of current electric energy is more and more, and power consumption equipment is more and more, and in power consumption equipment, has adopted low-power consumption, high integration and integrated circuit at a high speed again in a large number, and this just makes the electromagnetic interference problem of each equipment room highlighted greatly.

In the route of transmission of electromagnetic interference, power line is most important media because the length of power line (comprise equipment electric power incoming line and electric power transfer overhead wire and extend in) be enough to constitute effective antenna of radiofrequency signal.

Power-supply filter is mounted in a device that is specifically designed to the propagation of inhibition radiofrequency signal between power line and the equipment; Its effect is actually two-way; Can effectively stop extraneous electromagnetic interference through the power line access arrangement, can stop that again the electromagnetic interference that produces in the equipment self work gets into electrical network through power line.

In the development and application of current techniques; The difference of integrated equipment and the design of corresponding power supply do not have standardization; Part complete machine even also do not satisfy national standard; This will cause being used for assisting the loss decay surplus of the jamproof power-supply filter of complete machine more and more littler, make complete machine EMC (Electro Magnetic Compatibility) surpass the state compulsion standard, and national grid, human body are caused excessive electromagnetic radiation.Therefore must promote power-supply filter loss decay surplus as much as possible, increase and insert loss, make complete machine EMC be lower than the state compulsion standard, guarantee can not cause excessive electromagnetic radiation national grid, human body.

Figure is an example with Fig. 1 standard filtering principle; The low-pass filtering module that power-supply filter mainly is made up of passive component (resistance, electric capacity, inductance) usually; It is at when work consumed energy not, and it can allow power current to pass through, and for the electromagnetic interference wave of upper frequency very big decay is arranged.Electromagnetic interference mainly exists with the common mode form, and it is to suppress common mode disturbances that inductance L among Fig. 1 and capacitor C y mainly act on.Increase capacitor C y and can effectively improve the filter insertion loss value; But because capacitor C y connects electric power incoming line and casing ground; Therefore increasing capacitor C y then can corresponding increase leakage current over the ground, and the safety problem that causes personnel to shock by electricity easily is especially on Medical Devices; In order to reduce earth leakage current, sometimes even do not have a capacitor C y.Therefore, the impedance of raising inductance L becomes increases the key that power-supply filter inserts loss.

The performance that improves inductance mainly is to increase impedance, and the actual electrical sensor has been because distributed capacitance and series resistance have produced a self-resonant frequency, according to the formula of inductance parallel impedance:

$Z\∝\frac{1}{2\mathrm{\πf}{C}_w-\frac{1}{2\mathrm{\πfL}}}$

When self-resonant frequency was lower than resonance frequency fr, the parallel impedance Z of inductor depended mainly on 2 π fL, and wherein L representes the inductance value of product, so inductance presents perception, and the same with the common electrical sensor, its impedance increases with frequency.When humorous frequency is higher than resonance frequency fr, the parallel impedance Z of inductor depends mainly on 1/ (2 π fC _w), C wherein _wThe capacitance of expression product, so inductor presents capacitive reactances and increases with frequency and reduce.

In general power-supply filter; The effect of common mode inductance L is mainly used in the common mode disturbances that filtering is lower than resonance frequency fr (being generally about 5MHz), and (5MHz～common mode disturbances 30MHz) is then because rapid decline of inductor impedance causes inhibitory action less to be higher than resonance frequency fr.According to above-mentioned impedance computation formula, when being higher than resonance frequency, inductor is owing to present capacitive, so distributed capacitance C _wMore little, then impedance Z will be big more.

Because the volume miniaturization of various device and element now, the common mode inductance in the power-supply filter all adopts ring-like magnetic conductive media, for example ring-like high permeability FERRITE CORE etc. basically.In order to increase inductive impedance, often the number of turns of inductance coil is many, and is sandwich wound.If but winding mode is incorrect, distributed capacitance will increase significantly.Can know that by above-mentioned formula when being higher than resonance frequency fr, inductor parallel impedance Z depends mainly on 1/ (2 π f C _w), so the increase of distributed capacitance can cause the reduction of the impedance of inductance, and inductive impedance descends, and the filter insertion loss value will descend greatly, and therefore how reducing distributed capacitance becomes key, and does not also have the fine mode that addresses this problem at present.

The utility model content

The utility model provides a kind of common mode inductance, can reduce distributed capacitance, improves the insertion loss of inductor, has reduced the turn-to-turn voltage difference simultaneously, effectively prevents turn-to-turn short circuit.

The common mode inductance of the utility model comprises magnetic core, evenly is surrounded with the ground floor inductance coil on the surface of magnetic core along its periphery, is surrounded with the inductance coil that one deck section gap at least is provided with at the skin of ground floor inductance coil.What " evenly wrapped " was meant carries out the winding of inductance coil by equal densities.Because the size of distributed capacitance is proportional to two voltage difference and relative areas between the carrying object, is inversely proportional to the distance between them.After the typing of circuitry state, the voltage difference of corresponding inductor and relative area are just fixing thereupon, therefore have only the distance that strengthens between the carrying object, just can reduce distributed capacitance.Strengthen the compressive resistance between the carrying object, can effectively prevent turn-to-turn short circuit.The common mode inductance of the utility model has strengthened the distance between the carrying object through the structure with inductance coil segmentation coiling, has reduced distributed capacitance, has improved the insertion loss of inductor.Generally, can select suitable ring-like high permeability magnetic core, include models such as TL13 Φ 18 * Φ 10 * 8C, Φ 22 * Φ 14 * 8C or Φ 25 * Φ 15 * 13C according to complete machine EMC test status and power characteristic.

According to different application scenarios, the skin of ground floor inductance coil can wrapped any number of plies said inductance coil, a kind of preferred construction is the described inductance coil of outer wrapped one deck at the ground floor inductance coil.

In order to adapt to different occasions, outer each layer inductance coil of ground floor inductance coil is divided into 2～4 sections respectively at interval.The ground floor inductance coil is evenly arranged along the periphery of magnetic core, and its each outer layer is intervally arranged along the mode of magnetic core periphery with segmentation.Through experimental test, be preferably each layer inductance coil that the ground floor inductance coil is outer and be divided into 2 sections at interval respectively.

In order to improve the impedance of inductor, every layer of inductance coil is 14～70 circles.

Learn that through test equidistance is provided with the spacing of said each section on inductance coil, every layer inductance coil is arranged with uniform spacing segmentation, more help reducing distributed capacitance, improve and insert loss.

On this basis, the inductance coil of each layer is enamelled wire or three layer insulation wire, also can be other coil that is suitable for.Wherein the model of enamelled wire can be QA-2 Φ 0.3～Φ 1.8.

Through contrast test, the common mode inductance of the utility model can reduce distributed capacitance, improves the insertion loss of inductor, makes complete machine EMC (Electro Magnetic Compatibility) meet even be superior to national standard.Reduce the turn-to-turn voltage difference simultaneously, effectively prevented turn-to-turn short circuit, and simple in structure, be easy to processing.

Below in conjunction with embodiment, the foregoing of the utility model is remake further detailed description by the accompanying drawing illustrated embodiment.But should this be interpreted as that the scope of the above-mentioned theme of the utility model only limits to following instance.Do not breaking away under the above-mentioned technological thought situation of the utility model, various replacements or change according to ordinary skill knowledge and customary means are made all should be included in the scope of the utility model.

Description of drawings

A kind of principle schematic of Fig. 1 standard filtering.

Fig. 2 is the front view of the utility model common mode inductance.

Fig. 3 is the A-A view of Fig. 2.

The insertion loss comparison diagram of Fig. 4 tradition common mode inductance and the utility model common mode inductance.

Embodiment

The common mode inductance of the utility model comprises magnetic core 1 as shown in Figures 2 and 3, evenly is surrounded with ground floor inductance coil 2 on the surface of magnetic core 1 along its periphery, is surrounded with one deck at the skin of ground floor inductance coil 2 and is divided into 2 sections and the inductance coil 3 that is provided with at interval.The coil of same winding is middle respectively to the two ends coiling from magnetic core 1 during coiling, and every layer inductance coil is 14～70 circles.Outer field inductance coil 3 is arranged with uniform spacing segmentation, more help reducing distributed capacitance, improve and insert loss.According to complete machine EMC test status and power characteristic, select suitable ring-like high permeability magnetic core, the model that wherein is suitable for includes TL13 Φ 18 * Φ 10 * 8C, Φ 22 * Φ 14 * 8C or Φ 25 * Φ 15 * 13C etc.The inductance coil of each layer is enamelled wire or three layer insulation wire, also can be other coil that is suitable for.Wherein the model of enamelled wire can be QA-2 Φ 0.3～Φ 1.8.

As shown in Figure 4, through contrast test, obtain the correction data of inductor insertion loss in the table 1 to traditional common mode inductance and the utility model common mode inductance:

Table 1:

Hence one can see that, and the common mode inductance of the wrapped structure of the utility model segmentation can significantly reduce distributed capacitance, improves inductor and insert loss, reaches the purpose that makes complete machine EMC (Electro Magnetic Compatibility) meet even be superior to national standard.

Claims (7)

1. common mode inductance comprises magnetic core (1), it is characterized by on the surface of magnetic core (1) and evenly is surrounded with ground floor inductance coil (2) along its periphery, is surrounded with the inductance coil (3) that one deck section gap at least is provided with at the skin of ground floor inductance coil (2).

2. common mode inductance as claimed in claim 1 is characterized by the described inductance coil of outer wrapped one deck (3) at ground floor inductance coil (2).

3. common mode inductance as claimed in claim 1, it is characterized by described number of fragments is 2～4 sections.

4. common mode inductance as claimed in claim 3, it is characterized by described number of fragments is 2 sections.

5. common mode inductance as claimed in claim 1, it is characterized by every layer of inductance coil is 14～70 circles.

6. like the described common mode inductance of one of claim 1 to 5, it is characterized by at inductance coil (3) and go up the spacing that equidistance is provided with said each section.

7. common mode inductance as claimed in claim 6, the inductance coil that it is characterized by described each layer is enamelled wire or three layer insulation wire.

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