CN210183297U - Low-frequency-band filtering device and electrical equipment - Google Patents
Low-frequency-band filtering device and electrical equipment Download PDFInfo
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- CN210183297U CN210183297U CN201921266583.7U CN201921266583U CN210183297U CN 210183297 U CN210183297 U CN 210183297U CN 201921266583 U CN201921266583 U CN 201921266583U CN 210183297 U CN210183297 U CN 210183297U
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Abstract
The utility model discloses a low band filter and electrical equipment, the device includes: a basic filtering unit and a first low-frequency notch unit; the first low-frequency notch unit is arranged in the basic filtering unit; the basic filtering unit is used for filtering common-mode interference of a frequency band part outside a low-frequency band in a power supply to be filtered; the first low-frequency trap unit is used for providing a low-frequency common-mode interference low-impedance bypass path for common-mode interference of a low-frequency band part in the power supply. The utility model discloses a problem that makes the device cost increase by a wide margin for improving low band common mode filtering performance can be solved to the scheme, reaches the effect that reduces the device cost under the condition that improves low band common mode filtering performance.
Description
Technical Field
The utility model belongs to the technical field of the filtering, concretely relates to low band filter and electrical equipment especially relate to a low band conduction common mode interference trap circuit and domestic appliance.
Background
The common mode filter is used for filtering common mode interference generated by electrical equipment so as to meet the requirements of electromagnetic compatibility standards. A common structure of the common-mode filter includes a common-mode capacitor (also referred to as Y capacitor) and a common-mode inductor, and common-mode interference is reduced by a common-mode impedance of the common-mode inductor and a bypass effect of the common-mode capacitor. The common mode filter is generally used for conducting electromagnetic interference, and the action frequency band is 150kHz-30 mHz.
The excessive conducted electromagnetic interference at low frequency bands (150kHz to about 700kHz) is a common problem encountered in the electromagnetic compatibility test. For low-frequency common-mode interference, the capacitance value of the common-mode capacitor is generally required to be increased to improve the filtering performance, but the increase of the capacitance value is restricted by electrical safety and leakage current. Increasing the filter order can improve the low-band common-mode filtering performance, but the device cost is greatly increased. In some active common mode filter circuits, high-voltage transistors and auxiliary power supplies are needed, reliability is poor, and circuit cost is high.
The above is only for the purpose of assisting understanding of the technical solutions of the present invention, and does not represent an admission that the above is the prior art.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to the above-mentioned defect, provide a low band filter equipment and electrical equipment to solve the problem that makes the device cost increase by a wide margin for improving low band common mode filtering performance, reach the effect that reduces the device cost under the condition that improves low band common mode filtering performance.
The utility model provides a low band filtering device, include: a basic filtering unit and a first low-frequency notch unit; the first low-frequency notch unit is arranged in the basic filtering unit; the basic filtering unit is used for filtering common-mode interference of a frequency band part outside a low-frequency band in a power supply to be filtered; the first low-frequency trap unit is used for providing a low-frequency common-mode interference low-impedance bypass path for common-mode interference of a low-frequency band part in the power supply.
Optionally, the basic filtering unit includes: the first magnetic ring, the first common mode choke coil, the first common mode capacitor and the second common mode capacitor; the first magnetic ring is arranged at the L, N line of a power inlet wire of the power supply; the first low-frequency trap unit, the first common-mode capacitor and the second common-mode capacitor are sequentially arranged between an L, N line of a power supply inlet wire and a ground wire in parallel, and the first low-frequency trap unit is positioned between the first magnetic ring and the first common-mode capacitor; the first common mode choke coil is arranged on a L, N line of a power supply inlet wire and is positioned between the first common mode capacitor and the second common mode capacitor.
Optionally, the first magnetic ring includes: a low-frequency-band magnetic ring with an impedance value above a preset value; the low frequency section magnetic ring includes: high-conductivity manganese-zinc ferrite magnetic ring, or nanocrystalline or amorphous magnetic ring.
Optionally, the first low frequency notch unit includes: a first trap capacitor and a first low-frequency trap inductor; and the common end of the first trap capacitor is grounded after passing through the first low-frequency trap inductor.
Optionally, the first low frequency notch unit further includes: a first low frequency trap resistance; and the common end of the first trap capacitor is grounded after sequentially passing through the first low-frequency trap inductor and the first low-frequency trap resistor.
Optionally, a capacitance value of the first trap capacitor is smaller than a capacitance value of the first common-mode capacitor; and/or, the first notch capacitance, comprising: ceramic capacitors or thin film capacitors.
Optionally, the method further comprises: a second low frequency trap unit; the second low-frequency notch unit is arranged between an L, N line of a power supply outlet line and a ground line and is positioned on one side, far away from the power supply, of the basic filtering unit.
Optionally, the second low frequency notch unit has the same structure as the first low frequency notch unit; alternatively, the resonance frequency of the second low-frequency trap unit is shifted from the resonance frequency of the first low-frequency trap unit by a predetermined value.
With the above device phase-match, the utility model discloses another aspect provides an electrical equipment, include: the low band filtering device described above.
The utility model discloses a scheme, through utilizing the series resonance principle to provide low frequency common mode interference's low impedance bypass, realize low frequency section common mode conduction electromagnetic interference's filtering with low costs.
Further, the utility model discloses a scheme, through utilizing the series resonance principle to provide low frequency common mode interference's low impedance bypass route, the filter order reduces, and the power cord is qualified for the next round of competitions a department magnetic ring and reduces, circuit device cost reduction.
Further, the utility model discloses a scheme provides low frequency common mode interference's low impedance bypass route through utilizing the series resonance principle, reduces the device cost under the condition that improves low frequency section common mode filtering performance, and good reliability.
Therefore, the utility model discloses a scheme provides low frequency common mode interference's low impedance bypass path through utilizing the series resonance principle, solves the problem that makes the device cost increase by a wide margin for improving low band common mode filtering performance, reaches the effect that reduces the device cost under the condition that improves low band common mode filtering performance.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention.
The technical solution of the present invention is further described in detail by the accompanying drawings and examples.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of a low-band filtering apparatus according to the present invention, specifically, a schematic structural diagram of a low-frequency common-mode trap circuit;
fig. 2 is a schematic structural diagram of another embodiment of the low-band filtering apparatus of the present invention, specifically, a schematic structural diagram of a two-stage notch circuit for low-frequency filtering;
FIG. 3 is a schematic diagram of a conventional two-stage filter circuit;
FIG. 4 is a schematic diagram illustrating the effect of a conducted EMI test based on FIG. 3;
fig. 5 is a schematic diagram illustrating the effect of a conducted EMI test based on fig. 1.
With reference to the accompanying drawings, the embodiments of the present invention have the following reference numerals:
y1 — first Y capacitance; y2 — second Y capacitance; c1-a first notch capacitance; c2-a second notch capacitance; l is1-a first notch inductance; l is2-a second notch inductance; r1-a first trap resistance; r2-a second trap resistance.
Detailed Description
To make the purpose, technical solution and advantages of the present invention clearer, the following will combine the embodiments of the present invention and the corresponding drawings to clearly and completely describe the technical solution of the present invention. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
According to the utility model discloses an embodiment provides a low band filter device. Referring to fig. 1, a schematic structural diagram of an embodiment of the apparatus of the present invention is shown. The low band filtering apparatus may include: a basic filtering unit and a first low frequency notch unit. The first low frequency notch unit is disposed in the basic filtering unit.
The basic filtering unit can be used for filtering common-mode interference of a frequency band part outside a low-frequency band of a power supply to be filtered. The first low-frequency trap unit can be used for providing a low-frequency common-mode interference low-impedance bypass path for common-mode interference of a low-frequency band part in the power supply.
For example: in order to realize low-cost ground low-frequency range (150 kHz-about 700kHz) common mode conduction electromagnetic interference's filtering, the utility model discloses a scheme provides a low-frequency range conduction common mode interference trap circuit and domestic appliance, makes the filter order reduce, and the power cord is qualified for the next round of competitions a magnetic ring and is reduced, circuit device cost reduction. For example: the low-impedance bypass channel of the low-frequency common-mode interference is provided by utilizing the series resonance principle, the problem that the cost of the device is greatly increased for improving the low-frequency common-mode filtering performance can be solved, and the effect of reducing the cost of the device under the condition of improving the low-frequency common-mode filtering performance is achieved.
Therefore, the basic filtering unit and the first low-frequency trap unit are matched, so that the low-frequency filtering effect can be enhanced, and the effect of filtering and removing common-mode conducted electromagnetic interference can be enhanced.
In an optional example, the basic filtering unit may include: the magnetic circuit comprises a first magnetic ring, a first common mode choke coil, a first common mode capacitor and a second common mode capacitor.
The first magnetic ring is arranged at the L, N line of a power inlet wire of the power supply. The first low-frequency trap unit, the first common-mode capacitor and the second common-mode capacitor are sequentially arranged between an L, N line of a power supply inlet wire and a ground wire in parallel, and the first low-frequency trap unit is located between the first magnetic ring and the first common-mode capacitor. The first common mode choke coil is arranged on a L, N line of a power supply inlet wire and is positioned between the first common mode capacitor and the second common mode capacitor.
For example: after the low-frequency common-mode trap circuit with the structure of fig. 1 is used (the equivalent rectification principle is to increase the capacitance value of the Y capacitor), the use of a common-mode choke coil can be reduced, a ferrite/amorphous common-mode choke coil with good low-frequency suppression effect can be selected, 1-2 magnetic rings can be adjusted and used according to actual conditions, and an amorphous/nanocrystalline material is selected to ensure the high-frequency suppression effect, so that the effect is finally achieved as shown in fig. 5 (the margin of 12dB near the low-frequency 150K Hz is increased by 8 dB).
Therefore, the first magnetic ring, the first common-mode choke coil, the first common-mode capacitor and the second common-mode capacitor are matched, common-mode interference of a frequency band part between a low-frequency band part and a high-frequency band part in a power supply can be filtered, and the structure is simple.
Optionally, the first magnetic ring may include: and the low-frequency-band magnetic ring with the impedance value above a preset value. The low-frequency-band magnetic ring may include: high-conductivity manganese-zinc ferrite magnetic ring, or nanocrystalline or amorphous magnetic ring.
For example: in order to make the filter effect better, a proper magnetic ring can be added in the LN line, and a high-conductivity manganese-zinc ferrite magnetic ring or a nanocrystalline or amorphous magnetic ring with a high impedance value in a low frequency band is usually selected to enhance the low frequency filtering effect.
From this, through setting up the low frequency magnetic ring, can promote the low frequency filtering effect better under the condition of low cost.
In an alternative example, the first low frequency notch unit may include: a first notch capacitance and a first low frequency notch inductance.
And the common end of the first trap capacitor is grounded after passing through the first low-frequency trap inductor.
Therefore, the low-frequency trap unit is formed by the trap capacitor and the low-frequency trap inductor, the structure is simple, the low-frequency filtering effect can be enhanced, and the filtering reliability is high.
In a further optional example, the first low frequency notch unit may further include: a first low frequency trap resistance.
For example: the value of the trap resistor is generally 10-500 omega, and the resistance value of the trap resistor can be adjusted according to the required trap bandwidth. If the trap inductance adopts manganese-zinc ferrite, iron powder core, magnetic powder core, nanocrystalline or amorphous magnetic core, the loss tangent of the magnetic core is larger in the trap frequency band, the magnetic core loss can be utilized to generate damping, and the series trap resistance is omitted.
And the common end of the first trap capacitor is grounded after sequentially passing through the first low-frequency trap inductor and the first low-frequency trap resistor.
For example: a low band notch circuit (e.g., the first notch leg) is schematically illustrated in fig. 1. The low frequency trap circuit may include: a group of trap capacitors connected to the L line and the N line respectively, connected in series with the trap inductor and the trap resistor, and then connected to the L line and the N lineAnd (3) ground. The notch capacitance and the notch inductance form a series resonant tank, and the resonant center frequency is usually but not limited to 100kHz-500 kHz. In FIG. 1, the notch capacitance (e.g., first notch capacitance C)1) A notch inductance (e.g., first notch inductance L)1) A trap resistance (e.g., first trap resistance R)1) A low impedance bypass path is formed and connected in parallel with the first common mode capacitor Y1 (e.g., Y capacitor) to reduce the impedance of the bypass path. Therefore, an upper low-impedance bypass path is connected in parallel to the first common-mode capacitor Y1 (such as a Y capacitor), so that the low-frequency filtering effect is enhanced.
Therefore, the low-frequency trap resistor is arranged in the low-frequency trap unit, so that the application range of low-frequency filtering can be better expanded, and the low-frequency filtering is accurate and reliable.
In the above embodiments, the setting manner of the notch capacitance may include at least one setting situation.
The first setting scenario: the capacitance value of the first trap capacitor is smaller than that of the first common-mode capacitor.
For example: the trap capacitance is typically between 0.1-10nF, with ceramic or thin film dielectric capacitance. The value of the trap capacitor is far smaller than that of a common-mode capacitor (such as a Y capacitor) so as to avoid adverse effects caused by parallel resonance of the trap capacitor and the Y capacitor.
The second setting scenario: the first trap capacitance may include: ceramic capacitors or thin film capacitors.
For example: the value of the trap inductance is generally between 50uH and 1mH, and nickel zinc ferrite or magnesium zinc ferrite is adopted, so that the Q value of the inductance is higher near the trap frequency point.
Therefore, the filtering requirements of different occasions can be met by setting parameters, forms and the like of the notch capacitors, and the method is flexible and convenient.
In an alternative embodiment, the method may further include: a second low frequency notch unit. The second low-frequency notch unit is arranged between an L, N line of a power outlet line and a ground line and is positioned on one side of the basic filtering unit far away from the power supply, namely the basic filtering unit is positioned on one side of the second common-mode capacitor far away from the first common-mode choke coil.
For example: to better notch the low frequency, a notch branch may also be connected in parallel at a second common mode capacitance Y2 (e.g., Y capacitance), as shown in fig. 2. In FIG. 2, the notch capacitance (e.g., first notch capacitance C)1And a second trap capacitance C2) A notch inductance (e.g., first notch inductance L)1And a second trap inductance L2) A trap resistance (e.g., first trap resistance R)1And a second trap resistance R2) And low-impedance bypass paths (such as a first notch branch and a second notch branch) are formed and are respectively connected with a first common-mode capacitor Y1 (such as a Y capacitor) and a second common-mode capacitor Y2 (such as a Y capacitor) in parallel to reduce the impedance of the bypass paths, so that the low-frequency filtering effect of the low-impedance bypass paths is enhanced. Therefore, the first common-mode capacitor Y1 (such as a Y capacitor) and the second common-mode capacitor Y2 (such as a Y capacitor) are respectively connected in parallel with one low-impedance bypass path, and the low-frequency filtering effect is enhanced.
Therefore, the filtering effect can be enhanced more accurately and reliably by adding the low-frequency trap unit, and the structure is simple.
Optionally, the second low frequency notch unit has the same structure as the first low frequency notch unit. Alternatively, the resonance frequency of the second low-frequency trap unit is shifted from the resonance frequency of the first low-frequency trap unit by a predetermined value.
For example: the value of the element of the second notch branch (such as the second low-frequency notch unit) can be the same as that of the element of the first notch branch (such as the first low-frequency notch unit), and the value of the element of the second notch branch can also be finely adjusted, so that the resonant frequencies of the first notch branch and the second notch branch are slightly staggered, the notch effect is achieved in a larger bandwidth, the problem of parameter consistency of devices is solved, and the staggered range of the resonant frequencies is generally 50kHz-400 kHz.
Therefore, the low-frequency filtering requirements of different occasions can be met by setting the structures, parameters and other forms of different low-frequency trap wave units, and the low-frequency filtering method is flexible and reliable.
Through a large amount of experimental verifications, adopt the technical scheme of the utility model, provide low frequency common mode interference's low impedance bypass route through utilizing the series resonance principle, realize low frequency section common mode conduction electromagnetic interference's filtering with low costs.
According to the utility model discloses an embodiment still provides an electrical equipment corresponding to low band filter device. The electric device may include: the low band filtering device described above.
In an optional implementation manner, in order to realize the filtering of the low-frequency band (150kHz to about 700kHz) common mode conducted electromagnetic interference with low cost, the utility model provides a low-frequency band conducted common mode interference trap circuit and a household appliance, so that the order of the filter is reduced, the magnetic ring at the power line outlet is reduced, and the cost of the circuit device is reduced.
In an optional example, the utility model discloses a scheme utilizes the series resonance principle to provide the low impedance bypass route of low frequency common mode interference, can solve and make the problem that the device cost increases by a wide margin for improving low band common mode filtering performance, reaches the effect that reduces the device cost under the condition that improves low band common mode filtering performance.
In an alternative embodiment, a specific implementation process of the scheme of the present invention can be exemplarily described with reference to the examples shown in fig. 1 to 5.
In general filter circuit design, a circuit form is often designed as shown in fig. 3, and a two-stage topology filter circuit is generally used, which is a common mode filter circuit composed of two sets of common mode chokes (such as a first common mode choke and a second common mode choke) and a Y capacitor. In fig. 3, the first common-mode capacitor Y1 (e.g., Y capacitor) and the second common-mode capacitor Y2 (e.g., Y capacitor) are used as common-mode filtering elements to filter common-mode interference.
For a specific embodiment, the result of conducting EMI measured by using the conventional two-stage filter circuit shown in fig. 3 is shown in fig. 4 (the margin around 150kHz at low frequency is only 4dB), and the adjustment means is usually to adjust the specification of the choke coil/change the specification of the magnetic ring/increase the capacitance of the Y capacitor/add a stage of filtering, so that the final effect of conducting EMI is shown in fig. 5; if the low-frequency common-mode trap circuit with the structure of fig. 1 is used (the equivalent rectification principle is to increase the capacitance value of the Y capacitor), the use of a common-mode choke coil can be reduced, a ferrite/amorphous common-mode choke coil with good low-frequency suppression effect can be selected, 1-2 magnetic rings can be adjusted and used according to actual conditions, and an amorphous/nanocrystalline material is selected to ensure the high-frequency suppression effect, so that the effect is finally achieved as shown in fig. 5 (the margin of 12dB near the low-frequency 150K Hz is increased by 8 dB). In fig. 4 and 5, RBW represents the bandwidth, MT represents the end-scan time, and Att 10dB AUTO 10dB represents the automatic attenuation.
A low band notch circuit (e.g., the first notch leg) is schematically illustrated in fig. 1. The low frequency trap circuit may include: and the group of trap capacitors are respectively connected with the L line and the N line, are connected with the trap inductor and the trap resistor in series and then are grounded. The notch capacitance and the notch inductance form a series resonant tank, and the resonant center frequency is usually but not limited to 100kHz-500 kHz.
In FIG. 1, the notch capacitance (e.g., first notch capacitance C)1) A notch inductance (e.g., first notch inductance L)1) A trap resistance (e.g., first trap resistance R)1) A low impedance bypass path is formed and connected in parallel with the first common mode capacitor Y1 (e.g., Y capacitor) to reduce the impedance of the bypass path. Therefore, an upper low-impedance bypass path is connected in parallel to the first common-mode capacitor Y1 (such as a Y capacitor), so that the low-frequency filtering effect is enhanced.
Alternatively, the trap capacitance is typically between 0.1-10nF, with ceramic or thin film dielectric capacitance. The value of the trap capacitor is far smaller than that of a common-mode capacitor (such as a Y capacitor) so as to avoid adverse effects caused by parallel resonance of the trap capacitor and the Y capacitor.
Optionally, the value of the trap inductance is generally between 50uH and 1mH, and nickel zinc ferrite or magnesium zinc ferrite is adopted, so that the Q value of the inductance is higher near the trap frequency point.
Optionally, the value of the trap resistor is generally 10-500 Ω, and the resistance of the trap resistor can be adjusted according to the required trap bandwidth. If the trap inductance adopts manganese-zinc ferrite, iron powder core, magnetic powder core, nanocrystalline or amorphous magnetic core, the loss tangent of the magnetic core is larger in the trap frequency band, the magnetic core loss can be utilized to generate damping, and the series trap resistance is omitted.
In an alternative embodiment, to better notch low frequencies, a notch branch may also be connected in parallel at a second common mode capacitance Y2 (e.g., Y capacitance), as shown in fig. 2. The value of the element of the second notch branch (such as the second low-frequency notch unit) can be the same as that of the element of the first notch branch (such as the first low-frequency notch unit), and the value of the element of the second notch branch can also be finely adjusted, so that the resonant frequencies of the first notch branch and the second notch branch are slightly staggered, the notch effect is achieved in a larger bandwidth, the problem of parameter consistency of devices is solved, and the staggered range of the resonant frequencies is generally 50kHz-400 kHz.
In FIG. 2, the notch capacitance (e.g., first notch capacitance C)1And a second trap capacitance C2) A notch inductance (e.g., first notch inductance L)1And a second trap inductance L2) A trap resistance (e.g., first trap resistance R)1And a second trap resistance R2) And low-impedance bypass paths (such as a first notch branch and a second notch branch) are formed and are respectively connected with a first common-mode capacitor Y1 (such as a Y capacitor) and a second common-mode capacitor Y2 (such as a Y capacitor) in parallel to reduce the impedance of the bypass paths, so that the low-frequency filtering effect of the low-impedance bypass paths is enhanced. Therefore, the first common-mode capacitor Y1 (such as a Y capacitor) and the second common-mode capacitor Y2 (such as a Y capacitor) are respectively connected in parallel with one low-impedance bypass path, and the low-frequency filtering effect is enhanced.
Optionally, in order to make the filter effect better, a suitable magnetic ring may be added to the LN line, and a high-conductivity manganese-zinc ferrite magnetic ring or a nanocrystalline or amorphous magnetic ring with a high impedance value in a low frequency band is usually selected to enhance the low frequency filtering effect.
Since the processes and functions implemented by the electrical apparatus of this embodiment substantially correspond to the embodiments, principles, and examples of the devices shown in fig. 1 to fig. 5, the descriptions of this embodiment are not detailed herein, and refer to the related descriptions in the foregoing embodiments, which are not described herein again.
Through a large amount of experimental verifications, adopt the technical scheme of the utility model, through utilizing the series resonance principle to provide low-frequency common mode interference's low impedance bypass, the filter order reduces, and the power cord is qualified for the next round of competitions a department magnetic ring and reduces, circuit device cost reduction.
According to the utility model discloses an embodiment still provides the low band filtering method of an electrical equipment corresponding to electrical equipment. The low-band filtering method of the electrical equipment can comprise the following steps: common mode interference of a frequency band part outside a low frequency band in a power supply to be filtered is filtered through a basic filtering unit; and a low-frequency common-mode interference low-impedance bypass path is provided for common-mode interference of a low-frequency band part in the power supply through the first low-frequency trap unit.
For example: in order to realize low-cost ground low-frequency range (150 kHz-about 700kHz) common mode conduction electromagnetic interference's filtering, the utility model discloses a scheme provides a low-frequency range conduction common mode interference trap circuit and domestic appliance, makes the filter order reduce, and the power cord is qualified for the next round of competitions a magnetic ring and is reduced, circuit device cost reduction. For example: the low-impedance bypass channel of the low-frequency common-mode interference is provided by utilizing the series resonance principle, the problem that the cost of the device is greatly increased for improving the low-frequency common-mode filtering performance can be solved, and the effect of reducing the cost of the device under the condition of improving the low-frequency common-mode filtering performance is achieved.
Therefore, the basic filtering unit and the first low-frequency trap unit are matched, so that the low-frequency filtering effect can be enhanced, and the effect of filtering and removing common-mode conducted electromagnetic interference can be enhanced.
Since the processes and functions implemented by the method of the present embodiment substantially correspond to the embodiments, principles, and examples of the electrical apparatus, reference may be made to the related descriptions in the foregoing embodiments without being detailed in the description of the present embodiment.
Through a large number of tests, the technical scheme of the embodiment is adopted, and the low-impedance bypass channel of the low-frequency common-mode interference is provided by utilizing the series resonance principle, so that the cost of the device is reduced under the condition of improving the low-frequency common-mode filtering performance, and the reliability is good.
In summary, it is readily understood by those skilled in the art that the advantageous modes described above can be freely combined and superimposed without conflict.
The above description is only an example of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (9)
1. A low band filtering apparatus, comprising: a basic filtering unit and a first low-frequency notch unit; the first low-frequency notch unit is arranged in the basic filtering unit; wherein the content of the first and second substances,
the basic filtering unit is used for filtering the common mode interference of the frequency band part outside the low frequency band in the power supply to be filtered;
the first low-frequency trap unit is used for providing a low-frequency common-mode interference low-impedance bypass path for common-mode interference of a low-frequency band part in the power supply.
2. The apparatus of claim 1, wherein the basic filtering unit comprises: the first magnetic ring, the first common mode choke coil, the first common mode capacitor and the second common mode capacitor; wherein the content of the first and second substances,
the first magnetic ring is arranged at the L, N line of a power inlet wire of the power supply;
the first low-frequency trap unit, the first common-mode capacitor and the second common-mode capacitor are sequentially arranged between an L, N line of a power supply inlet wire and a ground wire in parallel, and the first low-frequency trap unit is positioned between the first magnetic ring and the first common-mode capacitor;
the first common mode choke coil is arranged on a L, N line of a power supply inlet wire and is positioned between the first common mode capacitor and the second common mode capacitor.
3. The apparatus as claimed in claim 2, wherein the first magnetic ring comprises: a low-frequency-band magnetic ring with an impedance value above a preset value; the low frequency section magnetic ring includes: high-conductivity manganese-zinc ferrite magnetic ring, or nanocrystalline or amorphous magnetic ring.
4. The apparatus of claim 2 or 3, wherein the first low frequency notch unit comprises: a first trap capacitor and a first low-frequency trap inductor; wherein the content of the first and second substances,
and the common end of the first trap capacitor is grounded after passing through the first low-frequency trap inductor.
5. The apparatus of claim 4, wherein the first low frequency notch unit further comprises: a first low frequency trap resistance; wherein the content of the first and second substances,
and the common end of the first trap capacitor is grounded after passing through the first low-frequency trap inductor and the first low-frequency trap resistor in sequence.
6. The apparatus of claim 4, wherein a capacitance value of the first notch capacitor is smaller than a capacitance value of the first common mode capacitor;
and/or the presence of a gas in the gas,
the first notch capacitance includes: ceramic capacitors or thin film capacitors.
7. The apparatus of any of claims 1-3, further comprising: a second low frequency trap unit;
the second low-frequency notch unit is arranged between an L, N line of a power supply outlet line and a ground line and is positioned on one side, far away from the power supply, of the basic filtering unit.
8. The apparatus of claim 7, wherein said second low frequency notch unit has the same structure as said first low frequency notch unit;
alternatively, the first and second electrodes may be,
the resonance frequency of the second low-frequency trap unit is shifted from the resonance frequency of the first low-frequency trap unit by a predetermined value.
9. An electrical device, comprising: the low band filtering apparatus of any one of claims 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921266583.7U CN210183297U (en) | 2019-08-05 | 2019-08-05 | Low-frequency-band filtering device and electrical equipment |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201921266583.7U CN210183297U (en) | 2019-08-05 | 2019-08-05 | Low-frequency-band filtering device and electrical equipment |
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| CN210183297U true CN210183297U (en) | 2020-03-24 |
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