CN212850432U - High-insertion-loss passive EMI filter - Google Patents
High-insertion-loss passive EMI filter Download PDFInfo
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- CN212850432U CN212850432U CN202022283197.8U CN202022283197U CN212850432U CN 212850432 U CN212850432 U CN 212850432U CN 202022283197 U CN202022283197 U CN 202022283197U CN 212850432 U CN212850432 U CN 212850432U
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Abstract
The utility model discloses a high-insertion-loss passive EMI filter, which adopts a second-order filtering structure and comprises a first-order filtering structure and a second-order filtering structure; the second-order filtering structure comprises a common-mode inductor L2; the EMI filter is connected with high-frequency and low-frequency alternating current signals transmitted by a power grid and outputs the signals to subsequent equipment; the EMI filter is a device for inhibiting differential mode noise and common mode noise caused by high-frequency and low-frequency alternating current signals transmitted by a power grid. The utility model has simple and reasonable structure, selects iron, cobalt, nickel and silicon, phosphorus and boron amorphous materials as the inductance magnetic core, and adopts unconventional application combination, compared with the traditional ferrite magnetic core, the inductance is effectively increased under the same specification, and the magnetic core has good high and low frequency alternating current noise inhibition effect, and reduces common mode interference and differential mode interference; effectively improves the insertion loss of frequency points of 10kHz and 30MHz, and meets the test items of CE102, power line conduction emission and the like.
Description
Technical Field
The utility model relates to the field of electronic technology, concretely relates to electron electric power, semiconductor, medical equipment, industrial control, aerospace, communication, war industry, computer trade etc. more specifically relates to a high passive EMI wave filter of insertion loss.
Background
Industrial electronic devices are exposed to complex environments for a long time during use, and are subjected to various external environments, particularly to the impact of electromagnetic environments. With the soundness and perfection of laws and regulations and industry standards, various countries have successively made regulations and standards for electronic devices subject to electromagnetic compatibility assessment, such as FCC regulations, VDE regulations, GJB standards, and the like. Therefore, the electromagnetic compatibility test of the electronic equipment is a key performance index, is concerned by the industry, and needs to be subjected to key design and examination verification in the product research and development process and before release.
Noise generated by the electronic equipment is mainly transmitted into a power grid through a power line, and the noise is superimposed in the power grid to indirectly influence other equipment. In the electromagnetic compatibility test, conducted emission is used as an important test item, and in order to ensure that conducted emission interference is filtered as much as possible, a filter is often added at the front end of a power line to perform filtering processing, as shown in fig. 1.
However, in the market, there are many types of EMI filters for transmission and emission, and the topology structure, device selection type and parameters adopted in the design are different, which results in a great difference between the functional performance and the application scenario of the EMI filter. When the conductive transmission test device helps electronic products to pass through a power line, the effect is uneven. Particularly, in a conducted emission test, the insertion loss of frequency points of 10kHz and 30MHz is small, so that the test requirements cannot be met, and the test cannot pass.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that when the CE102 and power line conduction emission (frequency range 10 kHz-30 MHz) test is carried out, the EMI filter circulating in the existing market is matched, and the test item that the electronic equipment in special industries passes through the CE102 and the power line conduction emission can not be met; in a conduction emission test, the insertion loss of frequency points of 10kHz and 30MHz is small, the filtering effect is poor, the test requirements cannot be met, and the test cannot pass.
The utility model aims to provide a high passive EMI wave filter of insertion loss can effectively improve the insertion loss of 10kHz and 30MHz frequency point, promotes the filter effect, and the help customer passes through test items such as CE102 and power cord conduction transmission in standards such as GJB 151B, MIL-STD-461E, GB 4824.
The utility model discloses a following technical scheme realizes:
a high-insertion-loss passive EMI filter adopts a second-order filtering structure and comprises a first-order filtering structure and a second-order filtering structure; the second-order filtering structure comprises a common-mode inductor L2;
the EMI filter is connected with high-frequency and low-frequency alternating current signals transmitted by a power grid and outputs the signals to subsequent equipment; the EMI filter is a device for inhibiting differential mode noise and common mode noise caused by high-frequency and low-frequency alternating current signals transmitted by a power grid.
The working principle is as follows:
when the CE102 and power line conducted emission (frequency range is 10 kHz-30 MHz) test is carried out, the EMI filter circulating in the existing market is matched, and the test item that electronic equipment in special industries passes through the CE102 and power line conducted emission cannot be met; in a conduction emission test, the insertion loss of frequency points of 10kHz and 30MHz is small, the filtering effect is poor, the test requirements cannot be met, and the test cannot pass. The EMI filter designed by the scheme adopts a second-order filtering structure design and is a passive filter, so that differential mode noise and common mode noise caused by high-frequency and low-frequency alternating-current signals transmitted by a power grid in a frequency range of 10 kHz-30 MHz, and differential mode noise and common mode noise between lines and ground of a weakening line can be effectively suppressed; in particular, the second-order filtering structure adopts a common-mode inductor L2 to replace a differential-mode inductor in the prior art, and a differential-mode inductor magnetic core in the prior art is usually made of ferrite; and the utility model discloses in can adopt the common mode inductance L2 that the nickel zinc material was made, L2 adopts the unconventional coiling common mode inductance of using of nickel zinc material, and its advantage both can restrain the differential mode noise, also has the effect of better suppression common mode noise simultaneously.
The utility model discloses a EMI wave filter input is by electric wire netting afferent high frequency, low frequency alternating current signal, when being mingled with the high frequency component of exchanging in the input signal, has good suppression effect through first order filtering structure to the high frequency component of exchanging, and the high frequency component that is not suppressed flows to back one-level, passes through second order filtering structure again and suppresses the processing, and final output high frequency component is filtered, can not cause the interference through output to follow-up equipment. The low-frequency alternating current component is subjected to low frequency resistance by the first-order filtering structure, part of the alternating current component is suppressed, the high frequency is passed by the first-order filtering structure, and part of the low frequency is passed by the first-order filtering structure.
The utility model has the advantages of simple and reasonable structure, the filtering is effectual, can satisfy experimental requirement.
As a further preferable solution, the common mode inductor L2 includes an inductor L2a and an inductor L2b, and the inductor L2a and the inductor L2b are wound on the same second magnetic core, and the inductor L2a and the inductor L2b have the same number of turns and phase, and are wound in opposite directions. The second magnetic core is made of nickel-zinc materials.
The magnetic core selects nickel zinc material to make, replaces the magnetic core that traditional ferrite material made. The nickel-zinc material is usually applied to winding of the differential mode inductor, and the L2 adopts the nickel-zinc material to wind the common mode inductor in unconventional application, so that the differential mode inductor has the advantages of inhibiting differential mode noise and better inhibiting the common mode noise.
As a further preferable scheme, the second-order filtering structure further includes a capacitor C2, a capacitor C3, and a resistor R2, and the capacitor C2, the common-mode inductor L2, the capacitor C3, and the resistor R2 are connected in sequence;
the capacitor C2, the capacitor C3 and the resistor R2 are all connected in parallel between a live wire and a zero line of an alternating current power supply, and the inductance coil L2a and the inductance coil L2b are respectively connected in series on the live wire and the zero line of the alternating current power supply;
one end of the capacitor C2 is connected with one end of the inductance coil L2a, and the other end of the inductance coil L2a is connected with one end of the capacitor C3; the other end of the capacitor C2 is connected with one end of an inductance coil L2b, and the other end of the inductance coil L2b is connected with the other end of the capacitor C3.
As a further preferable scheme, the first-order filtering structure includes a common-mode inductor L1, and the common-mode inductor L1 is an amorphous magnetic core made of an amorphous substance; common mode inductance L1 includes inductance coil L1a and inductance coil L1b, and inductance coil L1a and inductance coil L1b coiling are on same amorphous magnetic core, inductance coil L1a and inductance coil L1b number of turns and phase place all are the same, and the winding direction is opposite.
As a further preferable scheme, the common mode inductor L1 uses an amorphous magnetic core made of iron, cobalt, nickel and amorphous substance of silicon, phosphorus and boron.
The magnetic core of the common mode inductor L1 is made of iron, cobalt, nickel and amorphous substances of silicon, phosphorus and boron materials, and replaces the traditional magnetic core made of ferrite. Compared with a ferrite magnetic core, the ferrite magnetic core has the advantages of larger inductance value under the same winding quantity, less winding quantity under the same inductance value, smaller inductance volume, wider application occasion and higher economical efficiency. When the input signal is mixed with low-frequency signal, it is controlled by inductive reactance X L2 pi fL, and increase inductance L, XLThe suppression effect on low-frequency alternating current signals is better. And also improves the effect of suppressing high-frequency AC components.
As a further preferable scheme, the first-order filtering structure further includes a resistor R1 and a capacitor C1, and the resistor R1, the capacitor C1 and the common-mode inductor L1 are connected in sequence;
the resistor R1 and the capacitor C1 are both connected in parallel between a live wire and a zero line of an alternating current power supply, and the inductance coil L1a and the inductance coil L1b are respectively connected in series on the live wire and the zero line of the alternating current power supply;
one end of the capacitor C1 is connected with one end of the inductance coil L1a, and the other end of the inductance coil L1a is connected with one end of the inductance L2 a; the other end of the capacitor C1 is connected to one end of the inductor L1b, and the other end of the inductor L1b is connected to one end of the inductor L2 b.
As a further preferable scheme, the filter further comprises a capacitor C4 and a capacitor C5, wherein the capacitor C4 and the capacitor C5 are arranged between the first-order filtering structure and the second-order filtering structure;
the capacitor C4 is connected in series with the capacitor C5 and then connected in parallel between the live wire and the zero wire of the alternating current power supply; the middle point between the capacitor C4 and the capacitor C5 is grounded. When the capacitor C1, the capacitor C2 and the capacitor C3 carry out AC component suppression, the AC component charges the capacitor, and the resistor R1 and the resistor R2 are connected in parallel with the capacitor C1 and the capacitor C3 to discharge the capacitor voltage; c4 and C5 connect the live wire L and the neutral wire N with the ground, and weaken common-mode interference between the live wire L and the neutral wire N.
As a further preferred option, the EMI filter is suitable for use in CE102 and power line conducted emission tests.
Preferably, the EMI filter is adapted to suppress differential mode noise and common mode noise caused by high-frequency and low-frequency ac signals in a frequency range of 10kHz to 30 MHz.
Compared with the prior art, the utility model, following advantage and beneficial effect have:
1. the second-order filtering structure of the utility model adopts the common mode inductor L2 to replace the differential mode inductor in the prior art, and the magnetic core of the differential mode inductor in the prior art is usually made of ferrite material; and the utility model discloses in can adopt the common mode inductance L2 that the nickel zinc material was made, L2 adopts the unconventional coiling common mode inductance of using of nickel zinc material, and its advantage both can restrain the differential mode noise, also has the effect of better suppression common mode noise simultaneously.
2. The magnetic core of the common mode inductor L1 with the first-order filtering structure is made of iron, cobalt and nickel and amorphous substances of silicon, phosphorus and boron materials, and replaces the traditional magnetic core made of ferrite materials; compared with a ferrite magnetic core, the ferrite magnetic core has the advantages that the inductance is larger under the same winding quantity, the winding quantity is less under the same inductance, the inductance volume is smaller, the application occasion is wider, and the economy is higher; and also improves the effect of suppressing high-frequency AC components.
3. The utility model has simple and reasonable structure, selects iron, cobalt, nickel, silicon, phosphorus and boron materials with amorphous materials and nickel-zinc as the inductance magnetic core, and adopts unconventional application combination, compared with the traditional ferrite magnetic core, the inductance is effectively increased under the same specification, and the inductance has good high and low frequency alternating current noise inhibition effect, and reduces common mode interference and differential mode interference; effectively improves the insertion loss of frequency points of 10kHz and 30MHz, and helps customers to pass test items such as CE102 and power line conducted emission in standards such as GJB 151B, MIL-STD-461E, GB 4824.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a diagram showing the connection of the test apparatus.
Fig. 2 is a schematic diagram of a prior art EMI filter.
Fig. 3 is a schematic structural diagram of the EMI filter of the present invention.
Figure 4 is based on the magnetic core of traditional ferrite material the utility model discloses a high insertion loss EMI wave filter insertion loss test data contrast picture that amorphous and nickel-zinc magnetic core material combination realized.
Fig. 5 is a diagram illustrating the effect of a conventional filter interference test.
Fig. 6 is the utility model discloses the filter interference test effect picture.
Detailed Description
To make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the following examples and drawings, and the exemplary embodiments and descriptions thereof of the present invention are only used for explaining the present invention, and are not intended as limitations of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail so as not to obscure the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "one embodiment," "an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, the terms "front", "back", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", "outer", etc. indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the scope of the present invention.
Example 1
As shown in fig. 1 to 3, the present invention relates to a high insertion loss passive EMI filter, which adopts a second-order filtering structure, including a first-order filtering structure and a second-order filtering structure; the second-order filtering structure comprises a common-mode inductor L2;
the EMI filter is connected with high-frequency and low-frequency alternating current signals transmitted by a power grid and outputs the signals to subsequent equipment; the EMI filter is a device for inhibiting differential mode noise and common mode noise caused by high-frequency and low-frequency alternating current signals transmitted by a power grid.
In this embodiment, the common mode inductor L2 includes an inductor L2a and an inductor L2b, and the inductor L2a and the inductor L2b are wound around the same second magnetic core, and the inductor L2a and the inductor L2b have the same turns and the same phase, and the winding directions are opposite. The second magnetic core is made of nickel-zinc materials.
The magnetic core selects nickel zinc material to make, replaces the magnetic core that traditional ferrite material made. The nickel-zinc material is usually applied to winding of the differential mode inductor, and the L2 adopts the nickel-zinc material to wind the common mode inductor in unconventional application, so that the differential mode inductor has the advantages of inhibiting differential mode noise and better inhibiting the common mode noise.
In this embodiment, as shown in fig. 3, the second-order filtering structure further includes a capacitor C2, a capacitor C3, and a resistor R2, where the capacitor C2, the common-mode inductor L2, the capacitor C3, and the resistor R2 are sequentially connected;
the capacitor C2, the capacitor C3 and the resistor R2 are all connected in parallel between a live wire and a zero line of an alternating current power supply, and the inductance coil L2a and the inductance coil L2b are respectively connected in series on the live wire and the zero line of the alternating current power supply;
one end of the capacitor C2 is connected with one end of the inductance coil L2a, and the other end of the inductance coil L2a is connected with one end of the capacitor C3; the other end of the capacitor C2 is connected with one end of an inductance coil L2b, and the other end of the inductance coil L2b is connected with the other end of the capacitor C3.
The EMI filter is suitable for being used in CE102 and power line conducted emission tests, and is suitable for inhibiting differential mode noise and common mode noise caused by high-frequency and low-frequency alternating current signals within the frequency range of 10 kHz-30 MHz.
The working principle is as follows:
when the CE102 and power line conducted emission (frequency range is 10 kHz-30 MHz) test is carried out, the EMI filter circulating in the existing market is matched, and the test item that electronic equipment in special industries passes through the CE102 and power line conducted emission cannot be met; in a conduction emission test, the insertion loss of frequency points of 10kHz and 30MHz is small, the filtering effect is poor, the test requirements cannot be met, and the test cannot pass. A schematic structural diagram of an EMI filter in the prior art is shown in fig. 2, where an inductor L2 in a second-order filtering structure is a differential-mode inductor, and a magnetic core of the differential-mode inductor is usually made of a ferrite material, so that an effect of suppressing common-film noise is poor; although the inductor L1 in the first-order filtering structure is a common-mode inductor, the inductor L1 is a ferrite core, and has a small inductance value under the same winding number, a larger winding number and a larger inductance volume under the same inductance value.
The EMI filter designed by the scheme adopts a second-order filtering structure design and is a passive filter, so that differential mode noise and common mode noise caused by high-frequency and low-frequency alternating-current signals transmitted by a power grid in a frequency range of 10 kHz-30 MHz, and differential mode noise and common mode noise between lines and ground of a weakening line can be effectively suppressed; in particular, the second-order filtering structure adopts a common-mode inductor L2 to replace a differential-mode inductor in the prior art, and a differential-mode inductor magnetic core in the prior art is usually made of ferrite; and the utility model discloses in can adopt the common mode inductance L2 that the nickel zinc material was made, L2 adopts the unconventional coiling common mode inductance of using of nickel zinc material, and its advantage both can restrain the differential mode noise, also has the effect of better suppression common mode noise simultaneously.
The utility model discloses a EMI wave filter input is by electric wire netting afferent high frequency, low frequency alternating current signal, when being mingled with the high frequency component of exchanging in the input signal, has good suppression effect through first order filtering structure to the high frequency component of exchanging, and the high frequency component that is not suppressed flows to back one-level, passes through second order filtering structure again and suppresses the processing, and final output high frequency component is filtered, can not cause the interference through output to follow-up equipment. The low-frequency alternating current component is subjected to low frequency resistance by the first-order filtering structure, part of the alternating current component is suppressed, the high frequency is passed by the first-order filtering structure, and part of the low frequency is passed by the first-order filtering structure.
The utility model has the advantages of simple and reasonable structure, the filtering is effectual, can satisfy experimental requirement.
Example 2
As shown in fig. 1 to 6, the present embodiment is different from embodiment 1 in that, as shown in fig. 3, the first-order filtering structure includes a common-mode inductor L1, and the common-mode inductor L1 is an amorphous magnetic core made of an amorphous substance; common mode inductance L1 includes inductance coil L1a and inductance coil L1b, and inductance coil L1a and inductance coil L1b coiling are on same amorphous magnetic core, inductance coil L1a and inductance coil L1b number of turns and phase place all are the same, and the winding direction is opposite.
In this embodiment, the common mode inductor L1 is an amorphous magnetic core made of iron, cobalt, nickel, and amorphous substance of silicon, phosphorus, and boron.
The magnetic core of the common mode inductor L1 is made of iron, cobalt, nickel and amorphous substances of silicon, phosphorus and boron materials, and replaces the traditional magnetic core made of ferrite. Compared with a ferrite magnetic core, the ferrite magnetic core has the advantages of larger inductance value under the same winding quantity, less winding quantity under the same inductance value, smaller inductance volume, wider application occasion and higher economical efficiency. When the input signal is mixed with low-frequency signal, it is controlled by inductive reactance X L2 pi fL, and increase inductance L, XLThe suppression effect on low-frequency alternating current signals is better. And also improves the effect of suppressing high-frequency AC components.
In this embodiment, the first-order filtering structure further includes a resistor R1 and a capacitor C1, and the resistor R1, the capacitor C1 and the common-mode inductor L1 are connected in sequence;
the resistor R1 and the capacitor C1 are both connected in parallel between a live wire and a zero line of an alternating current power supply, and the inductance coil L1a and the inductance coil L1b are respectively connected in series on the live wire and the zero line of the alternating current power supply;
one end of the capacitor C1 is connected with one end of the inductance coil L1a, and the other end of the inductance coil L1a is connected with one end of the inductance L2 a; the other end of the capacitor C1 is connected to one end of the inductor L1b, and the other end of the inductor L1b is connected to one end of the inductor L2 b.
In this embodiment, the filter further includes a capacitor C4 and a capacitor C5, where the capacitor C4 and the capacitor C5 are disposed between the first-order filter structure and the second-order filter structure;
the capacitor C4 is connected in series with the capacitor C5 and then connected in parallel between the live wire and the zero wire of the alternating current power supply; the middle point between the capacitor C4 and the capacitor C5 is grounded. When the capacitor C1, the capacitor C2 and the capacitor C3 carry out AC component suppression, the AC component charges the capacitor, and the resistor R1 and the resistor R2 are connected in parallel with the capacitor C1 and the capacitor C3 to discharge the capacitor voltage; c4 and C5 connect the live wire L and the neutral wire N with the ground, and weaken common-mode interference between the live wire L and the neutral wire N.
The high insertion loss EMI filter insertion loss test data realized by the combination of the amorphous and nickel-zinc magnetic core material based on the traditional ferrite material are respectively shown in (3a) and (3b) in figure 4, (3a) is the magnetic core insertion loss of the traditional ferrite material, (3b) is the amorphous and nickel-zinc magnetic core insertion loss of the utility model, (3a) has a steep insertion loss curve, and the insertion loss of 10kHz and 30MHz frequency points is smaller; (3b) the insertion loss curve in (1) is smooth, the insertion loss at the frequency points of 10kHz and 30MHz is large, and the test items such as CE102 and power line conduction emission in the GJB 151B, MIL-STD-461E, GB 4824 standard can be met.
The working principle is as follows: when the input signal is mixed with a high-frequency alternating-current component, the capacitor C1 and the inductor L1 of the first-order filter structure have a good suppression effect on the high-frequency alternating-current component, the high-frequency component which is not suppressed flows to the next stage through the inductor L1, and is subjected to suppression processing through the capacitor C2, the inductor L2 and the capacitor C3 of the second-order filter structure, and finally the high-frequency component at the output end is filtered out, so that interference on subsequent equipment cannot be caused through the output end. The low-frequency alternating current component passes through the capacitor C1 and the inductor L1, the capacitor C1 blocks low frequency, partial alternating current component is suppressed, the inductor L1 passes high frequency, and partial low frequency passes. In order to better inhibit low-frequency alternating current components, the inductor L1 is designed to adopt iron, cobalt, nickel and silicon, phosphorus and boron materials as an inductor magnetic core, so that inductance is increased, and the effect of inhibiting low-frequency components is improved.
When in implementation: when the nuclear power plant security level DCS control system performs nuclear security bureau evidence obtaining, clear requirements are met for electromagnetism, and the interference of a power line to the outside needs to meet the requirements specified in RG1.180, namely the requirements of conduction emission CE 102. When the security level DCS cabinet is used for carrying out CE102 test, a filter is connected to the input end of a power line to inhibit the interference of conducted emission to the outside. The CE102 test is performed by using a common filter (i.e. a filter in the prior art) on the market, and the measured interference is assisted as shown in fig. 5, where the third point (1.31MHz) of the test curve is measured as: 74.26dBuV, limit: 73dBuV, which exceeds the limit of 1.26 dBuV; the fourth (1.345MHz) measured value is: 73.99dBuV, limit: 73dBuV, which exceeds the limit of 0.99 dBuV. In FIG. 5, the CE102 test measurement curve exceeds the limit line at the third point and the fourth point, and does not accord with the test requirement.
And adopt the utility model relates to a high insertion loss EMI wave filter, CE102 test measurement curve are shown in fig. 6, and in 200kHz ~ 2MHz frequency range, the interference amplitude has obvious improvement, reduces to below 50dBuV, is superior to and requires restriction 73 dBuV. In FIG. 6, each point on the CE102 test measurement curve does not exceed the limit line, and the test requirements are met.
Therefore, when the electronic device performs tests such as conducting transmission between the CE102 and the power line according to the standard such as the GJB 151B, MIL-STD-461E, GB 4824, a filter is connected to the input end of the power line in order to reduce interference to the outside. However, the conventional filter has poor noise suppression in a low frequency band (about 10 kHz) or a high frequency band (30MHz), and often cannot meet the test requirements. In order to avoid the defect, the high-insertion-loss passive EMI filter realized by the magnetic core made of iron, cobalt, nickel, silicon, phosphorus and boron materials designed by the utility model is adopted to pertinently improve the insertion loss of a low frequency band (about 10 kHz) and a high frequency band (30MHz) so as to achieve the purpose of helping electronic equipment to transmit test items such as CE102 and power line conduction in the GJB 151B, MIL-STD-461E, GB 4824 and other standards.
The above-mentioned embodiments, further detailed description of the objects, technical solutions and advantages of the present invention, it should be understood that the above description is only the embodiments of the present invention, and is not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A high-insertion-loss passive EMI filter is characterized in that the EMI filter adopts a second-order filtering structure and comprises a first-order filtering structure and a second-order filtering structure; the second-order filtering structure comprises a common-mode inductor L2;
the EMI filter is connected with high-frequency and low-frequency alternating current signals transmitted by a power grid and outputs the signals to subsequent equipment; the EMI filter is a device for inhibiting differential mode noise and common mode noise caused by high-frequency and low-frequency alternating current signals transmitted by a power grid.
2. The high insertion loss passive EMI filter of claim 1, wherein the common mode inductor L2 comprises an inductor L2a and an inductor L2b, and the inductor L2a and the inductor L2b are wound on the same second core, and the inductor L2a and the inductor L2b have the same turns and phase, and are wound in opposite directions.
3. The high insertion loss passive EMI filter of claim 2, wherein the second core is made of ni-zn material.
4. The high-insertion-loss passive EMI filter according to claim 2 or 3, wherein the second-order filtering structure further comprises a capacitor C2, a capacitor C3 and a resistor R2, and the capacitor C2, the common-mode inductor L2, the capacitor C3 and the resistor R2 are connected in sequence;
the capacitor C2, the capacitor C3 and the resistor R2 are all connected in parallel between a live wire and a zero line of an alternating current power supply, and the inductance coil L2a and the inductance coil L2b are respectively connected in series on the live wire and the zero line of the alternating current power supply;
one end of the capacitor C2 is connected with one end of the inductance coil L2a, and the other end of the inductance coil L2a is connected with one end of the capacitor C3; the other end of the capacitor C2 is connected with one end of an inductance coil L2b, and the other end of the inductance coil L2b is connected with the other end of the capacitor C3.
5. The high-insertion-loss passive EMI filter according to claim 1, wherein the first-order filtering structure comprises a common-mode inductor L1, the common-mode inductor L1 is an amorphous magnetic core made of amorphous substance;
common mode inductance L1 includes inductance coil L1a and inductance coil L1b, and inductance coil L1a and inductance coil L1b coiling are on same amorphous magnetic core, inductance coil L1a and inductance coil L1b number of turns and phase place all are the same, and the winding direction is opposite.
6. The high-insertion-loss passive EMI filter as claimed in claim 5, wherein said common-mode inductor L1 is an amorphous core made of iron, cobalt, nickel and amorphous substance of silicon, phosphorus, boron.
7. The high-insertion-loss passive EMI filter according to claim 5 or 6, wherein the first-order filtering structure further comprises a resistor R1 and a capacitor C1, and the resistor R1, the capacitor C1 and the common-mode inductor L1 are connected in sequence;
the resistor R1 and the capacitor C1 are both connected in parallel between a live wire and a zero line of an alternating current power supply, and the inductance coil L1a and the inductance coil L1b are respectively connected in series on the live wire and the zero line of the alternating current power supply;
one end of the capacitor C1 is connected with one end of the inductance coil L1a, and the other end of the inductance coil L1a is connected with one end of the inductance L2 a; the other end of the capacitor C1 is connected to one end of the inductor L1b, and the other end of the inductor L1b is connected to one end of the inductor L2 b.
8. The high insertion loss passive EMI filter according to claim 1, further comprising a capacitor C4, a capacitor C5, wherein the capacitor C4 and the capacitor C5 are disposed between the first-order filtering structure and the second-order filtering structure;
the capacitor C4 is connected in series with the capacitor C5 and then connected in parallel between the live wire and the zero wire of the alternating current power supply; the middle point between the capacitor C4 and the capacitor C5 is grounded.
9. The high insertion loss passive EMI filter of claim 1, wherein the EMI filter is adapted for use in CE102 and power line conducted emission testing.
10. The high insertion loss passive EMI filter of claim 9, wherein the EMI filter is adapted to suppress differential mode noise and common mode noise caused by high frequency and low frequency ac signals in the frequency range of 10kHz to 30 MHz.
Priority Applications (1)
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