阅读说明：本技术 一种滤波电路、电源电路及用电设备 (Filter circuit, power supply circuit and electric equipment ) 是由 黄强 吴洪清 吴勇 濮兴昕 吴赟 于 2021-08-04 设计创作，主要内容包括：本发明涉及一种滤波电路、电源电路及用电设备,该滤波电路通过共模扼流圈抑制电源出线侧的高频共模电磁干扰,通过共模滤波旁路将所述高频共模电磁干扰旁路到电源的地线上,通过带阻模块改变滤波单元的阻抗特性,吸收地线上的高频共模电磁干扰,提高了对高频共模电磁干扰的滤波效果。(The invention relates to a filter circuit, a power supply circuit and electric equipment, wherein the filter circuit inhibits high-frequency common-mode electromagnetic interference on the outgoing line side of a power supply through a common-mode choke coil, bypasses the high-frequency common-mode electromagnetic interference to the ground line of the power supply through a common-mode filter bypass, changes the impedance characteristic of a filter unit through a band elimination module, absorbs the high-frequency common-mode electromagnetic interference on the ground line, and improves the filtering effect on the high-frequency common-mode electromagnetic interference.)

1. A filter circuit, comprising:

at least one filtering unit, the filtering unit comprising:

the common mode choke coil is arranged on a zero line and a live line of the power supply and is used for inhibiting high-frequency common mode electromagnetic interference on the outgoing line side of the power supply;

the common-mode filtering bypass is used for bypassing the high-frequency common-mode electromagnetic interference to a ground wire of a power supply;

and the band elimination module is arranged on the ground wire of the power supply and used for absorbing high-frequency common-mode electromagnetic interference on the ground wire.

2. The filter circuit of claim 1,

the left side and the right side of the common mode choke coil are respectively provided with a differential mode filter capacitor;

and the differential mode filter capacitor is used for absorbing high-frequency differential mode electromagnetic interference on the power supply outgoing line side.

3. The filter circuit of claim 1,

the left side and the right side of the common mode choke coil are respectively provided with the common mode filtering bypass; and/or the presence of a gas in the gas,

the common mode filter bypass includes:

and the Y capacitor is bridged between the zero line, the live line and the ground wire of the power supply.

4. The filter circuit of claim 1,

and at least one band elimination module is respectively arranged on the ground wires on the left side and the right side of the common mode filtering bypass on the power supply incoming line side.

5. The filter circuit of claim 1,

at least one band elimination module is arranged on the ground wire between every two common mode filtering bypasses.

6. The filter circuit of claim 1,

the ground wire is connected with the shell ground;

at least one band elimination module is arranged on the ground wires on the left side and the right side of the shell.

7. The filter circuit of claim 6,

the closer to the chassis ground the band-stop module is, the lower its high-frequency impedance characteristic value is.

8. Filter circuit according to one of claims 1 to 7,

the band elimination module is one or more combination of the following forms, including:

the device comprises a resistor, an inductor, a resistor series inductor, a magnetic through bead and a magnetic ring.

9. A power supply circuit, comprising:

a filter circuit as claimed in any one of claims 1 to 8.

10. An electrical device, comprising:

the power supply circuit of claim 9.

Technical Field

The invention relates to the technical field of filter circuits, in particular to a filter circuit, a power supply circuit and electric equipment.

Background

A filter circuit is an essential part of circuit design as an important means for suppressing electromagnetic interference. The traditional filter circuit mainly uses a common-mode inductor matched with a Y capacitor to attenuate and bypass electromagnetic interference. However, the parasitic parameters of the common mode inductor seriously affect the high frequency impedance characteristics of the common mode inductor, so that the common mode inductor has an undesirable effect of suppressing high frequency electromagnetic interference. If the high-frequency interference is directly bypassed to the chassis ground, the electromagnetic interference is transmitted from the ground wire to the power line to radiate, so that the test is unqualified.

Referring to fig. 1, the prior art discloses a high-low band filtering device and an electrical apparatus. The filter device uses a high-frequency trap inductor to generate parallel resonance with a first Y capacitor Y1 and a second Y capacitor Y2 and a common mode choke parasitic capacitor, and is in a high-impedance state at high frequency, so that the high-frequency common mode interference is restrained from flowing into the ground wire. However, the parasitic parameters of the common mode choke coil cause the high frequency impedance characteristics thereof to be poor, and high frequency interference can directly propagate through the L, N wire, so that the power line radiation test result is poor.

Referring to fig. 2, the prior art discloses an EMI filtering apparatus having power filtering and signal filtering. The filter device adds a pair of grounding feedthrough filters consisting of an inductor and a series feedthrough capacitor in a power supply filter circuit to improve the high-frequency filtering effect. However, the high-frequency interference bypassed to the ground by the grounded capacitor can be spatially coupled to the power line, so that the filter circuit fails, or the high-frequency interference on the ground directly causes that the power line radiation can not pass the test.

Disclosure of Invention

In view of the above, the present invention provides a filter circuit, a power circuit and an electric device, so as to solve the problem in the prior art that the filter circuit has a poor effect of suppressing high-frequency common-mode electromagnetic interference.

According to a first aspect of embodiments of the present invention, there is provided a filter circuit including:

at least one filtering unit, the filtering unit comprising:

the common mode choke coil is arranged on a zero line and a live line of the power supply and is used for inhibiting high-frequency common mode electromagnetic interference on the outgoing line side of the power supply;

the common-mode filtering bypass is used for bypassing the high-frequency common-mode electromagnetic interference to a ground wire of a power supply;

and the band elimination module is arranged on the ground wire of the power supply and used for absorbing high-frequency common-mode electromagnetic interference on the ground wire.

Preferably, the left side and the right side of the common mode choke coil are respectively provided with a differential mode filter capacitor;

and the differential mode filter capacitor is used for absorbing high-frequency differential mode electromagnetic interference on the power supply outgoing line side.

Preferably, the left side and the right side of the common mode choke coil are respectively provided with one common mode filtering bypass; and/or, the common-mode filter bypass, comprising:

and the Y capacitor is bridged between the zero line, the live line and the ground wire of the power supply.

Preferably, at least one band elimination module is respectively arranged on the ground wires on the left side and the right side of the common mode filter bypass on the power supply incoming line side.

Preferably, at least one band elimination module is arranged on the ground wire between every two common mode filter bypasses.

Preferably, the ground wire is connected with the chassis ground;

at least one band elimination module is arranged on the ground wires on the left side and the right side of the shell.

Preferably, the higher the band-stop module is closer to the chassis ground, the lower its high-frequency impedance characteristic value is.

The band elimination module is one or more combination of the following forms, including:

the device comprises a resistor, an inductor, a resistor series inductor, a magnetic through bead and a magnetic ring.

According to a second aspect of embodiments of the present invention, there is provided a power supply circuit including:

the filter circuit described above.

According to a third aspect of embodiments of the present invention, there is provided an electric device, including:

the power supply circuit described above.

The technical scheme provided by the embodiment of the invention can have the following beneficial effects:

the common mode choke coil is used for inhibiting the high-frequency common mode electromagnetic interference on the line outgoing side of the power supply, the high-frequency common mode electromagnetic interference is bypassed to the ground line of the power supply through the common mode filtering bypass, the impedance characteristic of the filtering unit is changed through the band elimination module, the high-frequency common mode electromagnetic interference on the ground line is absorbed, and the filtering effect on the high-frequency common mode electromagnetic interference is improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a circuit schematic of a filter circuit according to the background art;

FIG. 2 is a circuit schematic of a filter circuit according to the background art;

FIG. 3 is a circuit schematic of a filter circuit shown in accordance with an exemplary embodiment;

FIG. 4 is a schematic diagram of a band-stop module shown in accordance with an exemplary embodiment;

FIG. 5 is a schematic diagram illustrating an EMI test of a powered device without the filter circuit of FIG. 3, in accordance with an exemplary embodiment;

FIG. 6 is a schematic diagram illustrating an EMI test of a powered device using the filter circuit of FIG. 3, according to an exemplary embodiment.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the invention, as detailed in the appended claims.

It should be noted that the high-frequency electromagnetic interference (including high-frequency common-mode electromagnetic interference and high-frequency differential-mode electromagnetic interference) mentioned in the present invention refers to electromagnetic interference with a frequency band between 10 mhz and 30 mhz; the low-frequency electromagnetic interference (including low-frequency common-mode electromagnetic interference and low-frequency differential-mode electromagnetic interference) referred to in the invention refers to electromagnetic interference with a frequency range of 150 kHz-700 kHz.

Example one

Fig. 3 is a diagram illustrating a filter circuit according to an exemplary embodiment, the filter circuit, as shown in fig. 3, including:

at least one filtering unit 10, said filtering unit 10 comprising:

a common mode choke (such as the common mode choke 1 or the common mode choke 2 in fig. 3) disposed on the neutral line and the live line of the power supply for suppressing high-frequency common mode electromagnetic interference on the outgoing line side of the power supply;

the common-mode filtering bypass 11 is used for bypassing the high-frequency common-mode electromagnetic interference to a ground wire of a power supply;

the band elimination module (such as the band elimination module 1, the band elimination module 2, the band elimination module 3 and the band elimination module 4 in fig. 3) is arranged on a ground wire of the power supply and used for absorbing high-frequency common-mode electromagnetic interference on the ground wire.

It can be understood that, in the technical scheme provided in this embodiment, the common mode choke coil is used to suppress the high-frequency common mode electromagnetic interference on the outgoing line side of the power supply, the common mode filter bypass bypasses the high-frequency common mode electromagnetic interference to the ground line of the power supply, the band rejection module is used to change the impedance characteristic of the filter unit, so as to absorb the high-frequency common mode electromagnetic interference on the ground line, and improve the filtering effect on the high-frequency common mode electromagnetic interference.

Preferably, the first and second electrodes are, as seen in figure 3,

the left side and the right side of the common mode choke coil are respectively provided with a differential mode filter capacitor;

and the differential mode filter capacitor is used for absorbing high-frequency differential mode electromagnetic interference on the power supply outgoing line side.

In this embodiment, the differential-mode filter capacitor is an X capacitor.

For example, in fig. 3, the X capacitor 1 is disposed on the left side of the common mode choke coil 1, and the X capacitor 2 is disposed on the right side;

the common mode choke coil 2 is provided with an X capacitor 2 on the left side and an X capacitor 3 on the right side.

The left side and the right side of the common mode choke coil are respectively provided with the common mode filtering bypass; and/or the presence of a gas in the gas,

the common mode filter bypass 11 includes:

and the Y capacitor is bridged between the zero line, the live line and the ground wire of the power supply.

For example, in fig. 3, a Y capacitor 1 is provided on the left side of the common mode choke coil 1, and a Y capacitor 2 is provided on the right side; the left side of the common mode choke coil 2 is provided with a Y capacitor 2, and the right side is provided with a Y capacitor 3.

It should be noted that the X capacitor is a capacitor bridged between two lines (L-N) of the power line, and is generally a metal thin film capacitor; the Y capacitors are capacitors connected between the two lines of the power line and ground (L-E, N-E), respectively, and are typically present in pairs. The value of the Y capacitance cannot be too large based on the limitation of the leakage current, and typically the X capacitance is of the uF class and the Y capacitance is of the nF class. The X capacitor suppresses differential mode interference, and the Y capacitor suppresses common mode interference.

And at least one band elimination module is respectively arranged on the ground wires on the left side and the right side of the common mode filtering bypass on the power supply incoming line side.

At least one band elimination module is arranged on the ground wire between every two common mode filtering bypasses.

For example, in fig. 3, a band elimination module 1 is arranged on the left side of a Y capacitor 1 on the power supply incoming line side, and a band elimination module 2 is arranged on the right side; a band elimination module 2 is arranged between the Y capacitor 1 and the Y capacitor 2; and a band elimination module 3 and a band elimination module 4 are arranged between the Y capacitor 2 and the Y capacitor 3.

The advantage of setting up like this lies in, guarantees that high frequency common mode electromagnetic interference no matter through on what kind of route to the ground wire, all can be absorbed by the band elimination mould on the ground wire, guarantees the filtering effect.

The ground wire is connected with the shell ground;

at least one band elimination module is arranged on the ground wires on the left side and the right side of the shell.

The closer to the chassis ground the band-stop module is, the lower its high-frequency impedance characteristic value is.

For example, the band elimination module 3 and the band elimination module 4 are respectively arranged on the ground wires on the left side and the right side of the machine shell in fig. 3.

Referring to fig. 3, the band elimination module 1, the band elimination module 2, the band elimination module 4 and the band elimination module 3 can be set, and the characteristic value can be measured by an impedance analyzer. The advantage of this kind of setting is that make the high frequency differential mode electromagnetic interference of power outgoing line side absorbed by the filtering unit of being close to casing ground as far as possible, reduces the propagation path of high frequency electromagnetic differential mode electromagnetic interference, improves the filtering effect.

Referring to fig. 4, the band-stop module is in the form of one or more of the following combinations, including:

the device comprises a resistor, an inductor, a resistor series inductor, a magnetic through bead and a magnetic ring.

The resistance impedance is generally less than 1K omega, and a cement resistor is generally selected; the inductor adopts an I-shaped inductor or a common annular differential mode inductor, and the inductance is generally 0.1 uH-3 uH.

Referring to fig. 3, the filter circuit shown in fig. 3 includes two filter units, which are second-order filter circuits, and the second-order filter circuits operate according to the following principle:

when low-frequency electromagnetic interference arrives, one path passes through the Y capacitor 3, and the Y capacitor 3 bypasses the low-frequency electromagnetic interference to the ground wire; the other path passes through a common mode choke 2 and an X capacitor 3, the common mode choke 2 inhibits low-frequency common mode electromagnetic interference, and the X capacitor 3 absorbs low-frequency differential mode electromagnetic interference.

The low-frequency electromagnetic interference remaining after passing through the common mode choke 2 and the X capacitor 3 is further filtered by the next filtering unit, for example, the remaining low-frequency electromagnetic interference is bypassed to the ground through the Y capacitor 2 of the next filtering unit, the remaining low-frequency common mode electromagnetic interference is suppressed by the common mode choke 1, and the remaining low-frequency differential mode electromagnetic interference is absorbed by the X capacitor 2. The low-frequency electromagnetic interference remaining after passing through the common mode choke coil 1 and the X capacitor 2 is bypassed to the ground by the Y capacitor 1 and absorbed by the X capacitor 1.

After passing through the filter circuit shown in fig. 3, the low-frequency electromagnetic interference is either transmitted to the ground by the common-mode filter bypass, or is suppressed by the common-mode choke coil, or is absorbed by the common-mode filter capacitor, so that the filter circuit shown in fig. 3 can meet the filter characteristic test requirement of the low-frequency electromagnetic interference (the filter characteristic test of the low-frequency electromagnetic interference requires that the electromagnetic interference radiation values on the zero line and the live line are 0 as much as possible).

When high-frequency electromagnetic interference arrives, one path of the high-frequency common-mode electromagnetic interference passes through the Y capacitor 3, the Y capacitor 3 bypasses the high-frequency common-mode electromagnetic interference to the ground wire, and as the ground wire is provided with the band elimination module 4, the resistance module 4 absorbs the high-frequency common-mode electromagnetic interference and then discharges the residual common-mode electromagnetic interference to the chassis ground, the residual high-frequency common-mode electromagnetic interference on the ground wire is as small as possible; the other path passes through a common mode choke coil 2 and an X capacitor 3, the common mode choke coil 2 inhibits high-frequency common mode electromagnetic interference, and the X capacitor 3 absorbs high-frequency differential mode electromagnetic interference.

The residual high-frequency electromagnetic interference after passing through the common mode choke coil 2 and the X capacitor 3 can be further filtered by the next filtering unit, for example, the residual high-frequency electromagnetic interference bypasses to the ground wire through the Y capacitor 2 of the next filtering unit, because the ground wire is provided with the band elimination module 3, the resistance module 3 absorbs the high-frequency common mode electromagnetic interference, and then the residual common mode electromagnetic interference is released to the chassis ground, so that the residual high-frequency common mode electromagnetic interference on the ground wire is as small as possible; the residual high-frequency common mode electromagnetic interference is suppressed by the common mode choke coil 1, and the residual high-frequency differential mode electromagnetic interference is absorbed by the X capacitor 2. The residual high-frequency electromagnetic interference after passing through the common mode choke coil 1 and the X capacitor 2 can be bypassed to the ground wire by the Y capacitor 1, and because the ground wire is provided with the band elimination module 2 and the resistance module 3, the resistance modules 2 and 3 absorb the high-frequency common mode electromagnetic interference, and then the residual common mode electromagnetic interference is discharged to the chassis ground, so that the residual high-frequency common mode electromagnetic interference on the ground wire is as small as possible; and meanwhile, residual high-frequency differential mode electromagnetic interference is absorbed by the X capacitor 1.

After passing through the filter circuit shown in fig. 3, the high-frequency electromagnetic interference is either transmitted to the ground line by the common-mode filter bypass and absorbed by the band-stop module, or is suppressed by the common-mode choke coil or absorbed by the common-mode filter capacitor, so that the filter circuit shown in fig. 3 can meet the filter characteristic test requirement of the high-frequency electromagnetic interference (the filter characteristic test of the high-frequency electromagnetic interference requires that electromagnetic interference radiation values on the zero line, the live line and the ground line are 0 as much as possible).

It should be noted that the filter circuit shown in fig. 3 is only an example, and in a specific practice, the number of the filter units in the filter circuit shown in fig. 3 may be increased or decreased and the structure of the filter units may be changed as needed. For example, according to the line end impedance condition of the power supply outlet line side, the use of the X capacitor 3 and/or the Y capacitor 3 can be selectively reduced, and the filtering effect is ensured. Any variation in the circuit structure of the filter circuit provided in this embodiment is within the scope of the present embodiment.

In order to verify the filtering performance of the filter circuit shown in fig. 3, in a specific practice, the filter circuit shown in fig. 3 is installed in a variable frequency air conditioner. In the experiment, the band elimination module 1 adopts a ground wire single loop to penetrate through the nanocrystalline magnetic ring, the band elimination module 2 adopts a 200 omega/2W resistor, the band elimination module 3 adopts a 50 omega/2W resistor, and the band elimination module 4 adopts a 100 omega/2W resistor.

Referring to fig. 5, when the inverter air conditioner does not employ the filter circuit shown in fig. 3, high-frequency electromagnetic interference occurs; referring to fig. 6, after the inverter air conditioner adopts the filter circuit shown in fig. 3, the amplitude of the electromagnetic interference around 28MHz can be effectively reduced.

It can be understood that, according to the technical scheme provided by this embodiment, the band elimination module is added on the ground wire, so that the high-frequency impedance characteristic of each filtering unit is changed, electromagnetic interference is reasonably shunted, the common mode choke coil simultaneously plays a role, electromagnetic interference is attenuated, and the filtering effect is enhanced.

Example two

A power supply circuit according to an exemplary embodiment is shown, comprising:

the filter circuit described above.

It can be understood that, in the technical solution provided by this embodiment, because the filter circuit includes the above-mentioned filter circuit, the above-mentioned filter circuit suppresses the high-frequency common mode electromagnetic interference on the power supply line outlet side through the common mode choke coil, bypasses the high-frequency common mode electromagnetic interference to the ground line of the power supply through the common mode filter bypass, changes the impedance characteristic of the filter unit through the band elimination module, absorbs the high-frequency common mode electromagnetic interference on the ground line, and improves the filtering effect on the high-frequency common mode electromagnetic interference, therefore, the power supply circuit provided by this embodiment has a good filtering effect on the high-frequency common mode electromagnetic interference.

EXAMPLE III

An electrical device is shown according to an exemplary embodiment, comprising:

the power supply circuit described above.

It should be noted that the electric device includes, but is not limited to: various electric equipment such as a variable frequency air conditioner, a refrigerator, a washing machine, a television, a fresh air machine, a humidifier, an electric cooker and the like.

It can be understood that, in the technical solution provided by this embodiment, because the power circuit includes the power circuit, and the power circuit includes the filter circuit, and the filter circuit suppresses the high-frequency common-mode electromagnetic interference on the power line outlet side through the common-mode choke coil, bypasses the high-frequency common-mode electromagnetic interference to the ground line of the power supply through the common-mode filter bypass, changes the impedance characteristic of the filter unit through the band elimination module, absorbs the high-frequency common-mode electromagnetic interference on the ground line, and improves the filtering effect on the high-frequency common-mode electromagnetic interference, the electric device provided by this embodiment has a good filtering effect on the high-frequency common-mode electromagnetic interference.

It is understood that the same or similar parts in the above embodiments may be mutually referred to, and the same or similar parts in other embodiments may be referred to for the content which is not described in detail in some embodiments.

It should be noted that the terms "first," "second," and the like in the description of the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Further, in the description of the present invention, the meaning of "a plurality" means at least two unless otherwise specified.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.

It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may also be stored in a computer readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.