WO2019223801A1 - Common-mode electromagnetic noise extraction network and active electromagnetic interference filter - Google Patents

Abstract

The present invention relates to a common-mode electromagnetic noise extraction network and an active electromagnetic interference filter. The common-mode electromagnetic noise extraction network comprises an input cable connected between a power supply system and an electrical device, and a common-mode electromagnetic noise sampler and a common-mode electromagnetic noise extractor. The electromagnetic noise sampler is arranged between the input cable and the common-mode electromagnetic noise extractor, and is used for sampling differential and common-mode electromagnetic noise of the input cable and outputting the sampled differential and common-mode electromagnetic noise to the common-mode electromagnetic noise extractor. The common-mode electromagnetic noise extractor is used for extracting and outputting common-mode electromagnetic noise in the differential and common-mode electromagnetic noise sampled by the electromagnetic noise sampler.

Description

Common-mode electromagnetic noise extraction network and active electromagnetic interference filter Technical field

The invention relates to the field of filtering technology, in particular to a common-mode electromagnetic noise extraction network and an active electromagnetic interference filter.

Background technique

FIG. 1 is a schematic diagram of the connection between an electric device and a power supply system. As shown in Figure 1, with the increasing popularity of electrical equipment, high-frequency electromagnetic noise generated by electrical equipment will not only affect the surrounding electronic equipment, but also affect the power supply system. Therefore, in 1996, the European Union introduced electromagnetic compatibility (referred to as "EMC") regulatory requirements, forcing the use of electronic equipment using public power grids must meet the requirements of relevant EMC regulations. The power supply system may be an AC power supply system or a DC power supply system.

FIG. 2 is a schematic diagram of an application of a conventional passive EMI filter. As shown in Figure 2, in order to meet the electromagnetic interference (EMI) requirements in the EMC regulations, almost all electrical equipment will use passive EMI filters composed of passive components, connected in series to the electrical equipment and the power supply system. In order to suppress electromagnetic noise in electrical equipment, meet the requirements of EMI regulations limits, and avoid affecting the power supply system.

The typical structure of a passive EMI filter is composed of a common mode EMI filter and / or a differential mode EMI filter. FIG. 3 is a schematic diagram of a conventional common-mode EMI filter. As shown in Figure 3, the common-mode EMI filter consists of a common-mode inductor L _cm and a capacitor C _Y. FIG. 4 is a schematic diagram of a conventional differential mode EMI filter. As shown in FIG. 4, the differential mode EMI filter is composed of a differential mode inductor L _dm and a capacitor C _X.

Although a passive EMI filter can suppress electromagnetic noise, meet the requirements of EMI regulations, and avoid affecting the surrounding electronic equipment and the power supply grid, its series connection will cause many problems:

First, the losses are serious: when suppressing weak μA level electromagnetic noise, it is necessary to bear the load current of the electrical equipment at the same time, resulting in additional losses and heat generation, reducing the energy efficiency and reliability of the electrical equipment;

Second, the volume is huge: in order to withstand the load current of the electrical equipment, the volume of the common mode inductor and the differential mode inductance will inevitably increase, and even exceed the volume of the functional circuit of the electrical equipment, which will become upside down;

Third, the cost is increased: In order to meet the needs of electromagnetic noise suppression in different frequency bands, it is usually necessary to use common mode inductance of different magnetic materials to suppress electromagnetic noise in different frequency bands. This will inevitably lead to a multi-stage filtering architecture and eventually passive EMI filters The cost increases, the volume further increases, and at the same time, more losses and heat are caused;

Fourth, near-field coupling: Due to the large size of passive components and the influence of stray parameters, near-field coupling and resonance of electromagnetic noise occur in high frequency bands, causing the filtering effect to fall short of design expectations.

FIG. 5 is a conceptual diagram of a conventional active EMI filter. As shown in FIG. 5, in order to solve the defects of the conventional passive EMI filter, a conceptual structure of an active EMI filter is proposed. The active EMI filter will collect the electromagnetic noise current or voltage signal generated by the subsequent-stage electrical equipment, and achieve closed-loop feedback after gain amplification to achieve the purpose of noise suppression.

Other known active EMI filters use a common winding with a third coupling winding to extract common-mode electromagnetic noise flowing through the common-mode inductor. After gain amplification, the capacitor is injected into the ground or A common-mode loop consisting of a housing to achieve common-mode noise suppression.

However, because the three windings of the common mode inductor cannot be completely coupled, there will always be about 3% to 5% of leakage inductance, so when coupled to the common mode electromagnetic noise, it is also coupled to part of the differential mode electromagnetic noise. The hybrid is amplified in the common-mode electromagnetic noise and injected into the common-mode loop, which finally results in a new common-mode electromagnetic noise caused by the mixed-mode electromagnetic noise, and thus does not achieve the expected common-mode electromagnetic noise suppression effect.

Some known active differential mode EMI filters obtain differential mode electromagnetic noise by sampling the inductor voltage signal connected in series on the DC bus, and after amplification processing, control the impedance of the MOSFET transistor to achieve the purpose of suppressing differential mode noise. . However, the DC bus of the power supply will include differential mode electromagnetic noise, as well as common mode electromagnetic noise. Therefore, the electromagnetic noise obtained from the inductor includes not only differential mode electromagnetic noise but also common mode electromagnetic noise. In this way, the differential-mode electromagnetic noise mixed with the common-mode electromagnetic noise is amplified and then injected into the differential-mode loop through the impedance change of the MOSFET transistor, which eventually causes new differential-mode electromagnetic noise caused by the common-mode electromagnetic noise, which eventually fails to reach the target. To the expected differential mode noise suppression effect.

Figure 6 is a test setup diagram of the existing standard conducted interference. As shown in Figure 6, a standard test setup diagram for conducted interference according to CISP16-1-2, in which a standard linear impedance matching network (LISN) is used in series between the power supply grid system and the electrical equipment to extract the equipment under test Conducted noise. In the conducted interference test, the electromagnetic noise detected by the receiver is extracted through a linear impedance matching network (LISN) coupling. As shown in FIG. 6, the electromagnetic noise current I _{input 1} flowing on the input cable 11 includes 1/2 of the common mode electromagnetic noise current I _CM and the differential mode electromagnetic noise current I _DM in the same direction. The electromagnetic noise current I _{input 2} flowing on the input cable 12 includes 1/2 common-mode electromagnetic noise current I _{CM in the} same direction and reverse differential-mode electromagnetic noise current I _{DM in the} same direction. The 1/2 common-mode electromagnetic noise current I _CM in the input cables 11 and 12 in the same direction will be returned to the receiver through the common-mode electromagnetic noise source 101 in the electrical equipment under test through the metal plate connected to the ground in the conduction test. As a result, the common mode electromagnetic noise current I _CM is detected by the receiver. The differential mode electromagnetic noise source 100 in the electrical equipment under test generates a differential mode electromagnetic current flowing in the input cables 11 and 12 in the reverse direction. After being coupled by the LISN, it is detected by the receiver.

The schematic diagram of the conventional active EMI filter shown in FIG. 5 is suitable for suppressing both common mode electromagnetic noise and differential mode electromagnetic noise. But common-mode electromagnetic noise and differential-mode electromagnetic noise have different propagation paths. Differential mode electromagnetic noise can only propagate through differential mode circuits. Common-mode electromagnetic noise will only propagate through the common-mode path, but it will overlap on the input cable and inside the power equipment, and the other half of the propagation path of the common-mode electromagnetic noise is detected by the electromagnetic interference test receiver. . Therefore, it is critical to completely isolate and inject the differential common-mode noise in the electrical equipment to achieve the suppression of the differential common-mode electromagnetic noise.

Summary of the Invention

The invention provides a common-mode electromagnetic noise extraction network and an active electromagnetic interference filter including the common-mode electromagnetic noise extraction network, which can use a small amount of common-mode electromagnetic noise of electric equipment or does not enter the power supply system.

An aspect of the present invention provides a common-mode electromagnetic noise extraction network including an input cable, an electromagnetic noise sampler, and a common-mode electromagnetic noise extractor adapted to be connected between a power supply system and an electric device; the electromagnetic noise sampling A device disposed between the input cable and the common mode electromagnetic noise extractor, and configured to sample the differential common mode electromagnetic noise of the input cable and output the sampled differential common mode electromagnetic noise to the input cable; Common-mode electromagnetic noise extractor; the common-mode electromagnetic noise extractor is used to extract and output common-mode electromagnetic noise among the differential common-mode electromagnetic noise sampled by the electromagnetic noise sampler.

Further, the input cable includes a first input cable and a second input cable connected in parallel; the electromagnetic noise sampler includes a first sampler and a second sampler; wherein the first sampler is disposed at On the first input cable, the first sampler is connected to the common mode electromagnetic noise extractor; the second sampler is disposed on the second input cable, and the second sampler is connected to The common mode electromagnetic noise extractor is connected.

Further, the input cable includes a first input cable and a second input cable in parallel; the electromagnetic noise sampler includes an inductor, and the inductor includes two primary windings and two secondary sampling windings; wherein Two primary windings and two secondary sampling windings are coupled in a one-to-one correspondence; one of the primary windings is connected in series between the first input cable and the electrical equipment, and the other is The primary winding is connected in series between the second input cable and the electrical equipment; two first ends of the two secondary sampling windings are connected to ground, and two of the two secondary sampling windings are connected to ground. The second end is used to output the differential common mode electromagnetic noise corresponding to the input cable.

Further, the input cable includes a first input cable and a second input cable connected in parallel; the common mode electromagnetic noise extractor includes a dual winding inductor; wherein the two windings have opposite polarities, and The first ends of the two windings are respectively used to receive differential common mode electromagnetic noise of the first input cable and the second input cable, and the second ends of the two windings are both used to output common mode electromagnetic noise. .

Further, the input cable includes a first input cable and a second input cable in parallel; the common-mode electromagnetic noise extractor includes a first operational amplifier, a first resistor R ₁ , a second resistor R ₂ , and a first resistor. three fourth resistors R ₃ and resistor _{R. 4;} wherein a first end of said first resistor R ₁ for receiving the first differential input cable common mode electromagnetic noise, the first of the second resistor R ₂ One end is used to receive the differential common mode electromagnetic noise of the second input cable, and the second end of the first resistor R _{1 and} the second end of the second resistor R ₂ are both connected to the first operational amplifier. The negative resistor R _{3 is} connected between the negative input terminal and the output terminal of the first operational amplifier; the fourth resistor R _{4 is} connected to the positive input terminal of the first operational amplifier And the ground.

The common-mode electromagnetic noise extraction network provided by the present invention samples the differential common-mode electromagnetic noise of an input cable through an electromagnetic noise sampler and outputs the sampled differential common-mode electromagnetic noise to a common-mode electromagnetic noise extractor, which is equivalent to the common-mode electromagnetic noise extractor. The noise extractor indirectly extracts common mode electromagnetic noise from the input cable of the electrical equipment. In the active electromagnetic interference filter, the extracted common mode electromagnetic noise is processed for gain and closed-loop feedback through the electromagnetic noise conversion network. After processing, The common mode electromagnetic noise is returned to the common mode noise source in the electric equipment through the common mode loop through the common mode electromagnetic noise injection network. In this way, the common mode electromagnetic noise of the electrical equipment can be small or even does not enter the power supply system, so that the surrounding environment and the power supply grid are not affected by the electromagnetic noise of the electrical equipment, and at the same time, the electrical equipment can meet the requirements of the EMI regulations. .

Another aspect of the present invention provides an active electromagnetic interference filter including the common mode electromagnetic noise extraction network as described above.

Further, the active electromagnetic interference filter further includes an electromagnetic noise conversion network and a common-mode electromagnetic noise injection network; the electromagnetic noise conversion network is configured to perform gain and closed-loop feedback processing on the common-mode electromagnetic noise; The common mode electromagnetic noise is returned to the electric equipment through the common mode electromagnetic noise injection network; the common mode electromagnetic noise extraction network, the electromagnetic noise conversion network, and the common mode electromagnetic noise injection network are sequentially connected.

The beneficial effects of the active electromagnetic interference filter provided by the present invention compared with the prior art and the beneficial effects of the common mode electromagnetic noise extraction network provided by the present invention compared with the prior art are not repeated here.

Overview of the drawings

In order to more clearly explain the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the specific embodiments or the description of the prior art will be briefly introduced below. Obviously, the appended descriptions in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without paying creative labor.

FIG. 1 is a schematic diagram of a connection between an electric device and a power supply system;

FIG. 2 is an application schematic diagram of an existing passive EMI filter;

FIG. 3 is a schematic diagram of a conventional common-mode EMI filter;

4 is a schematic diagram of a conventional differential mode EMI filter;

5 is a conceptual diagram of a conventional active EMI filter;

FIG. 6 is a test setup diagram of an existing standard conducted interference;

7 is a schematic diagram of a filtering technology of an active electromagnetic interference filter according to an embodiment of the present invention;

8 is a first schematic diagram of an electromagnetic noise processing network according to an embodiment of the present invention;

9 is a second schematic diagram of an electromagnetic noise processing network according to an embodiment of the present invention;

10 is a first schematic diagram of an electromagnetic noise sampler according to an embodiment of the present invention;

11 is a second schematic diagram of an electromagnetic noise sampler according to an embodiment of the present invention;

12 is a first schematic diagram of an electromagnetic noise extraction network provided by an embodiment of the present invention;

13 is a second schematic diagram of an electromagnetic noise extraction network provided by an embodiment of the present invention;

14 is a schematic diagram of a differential mode electromagnetic noise injection network based on a semiconductor transistor according to an embodiment of the present invention;

15 is a schematic diagram of a differential mode electromagnetic noise injection network based on a dual-winding differential mode inductor according to an embodiment of the present invention;

16 is a schematic diagram of a differential mode electromagnetic noise injection network based on a three-winding differential mode inductor according to an embodiment of the present invention;

17 is a schematic diagram of a capacitor-based common mode electromagnetic noise injection network according to an embodiment of the present invention;

18 is a schematic diagram of a common mode electromagnetic noise injection network based on a ground capacitor according to an embodiment of the present invention;

19 is a schematic diagram of a common mode electromagnetic noise injection network based on inductive electromagnetic according to an embodiment of the present invention;

20 is a simplified circuit diagram of an AC input power adapter according to an embodiment of the present invention;

21 is a simplified circuit diagram of a DC input switching power supply according to an embodiment of the present invention;

22 is a simplified circuit diagram of an AC input power adapter according to an embodiment of the present invention;

23 is a simplified circuit diagram of a DC input switching power supply according to an embodiment of the present invention;

24 is a schematic diagram of an electromagnetic noise conversion network according to an embodiment of the present invention;

25 is a schematic diagram of an active electromagnetic interference filter according to the first embodiment of the present invention;

FIG. 26 is a schematic diagram of an active electromagnetic interference filter according to a second embodiment of the present invention; FIG.

27 is a schematic diagram of an active electromagnetic interference filter according to a third embodiment of the present invention;

FIG. 28 is a schematic diagram of an active electromagnetic interference filter according to a fourth embodiment of the present invention; FIG.

FIG. 29 is a schematic diagram of an active electromagnetic interference filter according to Embodiment 5 of the present invention.

Reference signs:

100-differential mode electromagnetic noise source; 101-common mode electromagnetic noise source; 108-common mode electromagnetic noise component output terminal; 109-differential mode electromagnetic noise component output terminal; 11-first input cable; 12-second input line Cable; 111- electromagnetic noise of the first input cable; 121- electromagnetic noise of the second input cable; 21- electromagnetic noise processing network; 22- electromagnetic noise conversion network; 23- differential mode electromagnetic noise injection network; 25- total Mode electromagnetic noise injection network; 211-common mode electromagnetic noise extractor; 212-differential mode electromagnetic noise extractor; 213-electromagnetic noise sampler; 214-differential common mode electromagnetic noise extraction network; 215-first sampler; 216- Second sampler; 33-first operational amplifier; 34-second operational amplifier; 35-first resistance-capacitance network; 36-second resistance-capacitance network.

The preferred embodiment of the present invention

The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplified description, and does not indicate or imply that the device or element referred to must have a specific orientation, a specific orientation Construction and operation should therefore not be construed as limiting the invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only, and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installation", "connected", and "connected" should be understood in a broad sense unless explicitly stated and limited otherwise. For example, they may be fixed connections or removable. Connection, or integral connection; it can be mechanical or electrical connection; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

FIG. 7 is a schematic diagram of an active EMI filtering technology according to an embodiment of the present invention. Referring to FIG. 7, in view of the shortcomings of the conventional passive EMI filter and the existing active EMI filter, an embodiment of the present invention proposes an active EMI filtering technology for separately suppressing differential common mode electromagnetic noise. The electromagnetic interference filter implements this technique. The active electromagnetic interference filter includes an electromagnetic noise processing network 21, an electromagnetic noise conversion network 22, a differential mode electromagnetic noise injection network 23, and a common mode electromagnetic noise injection network 25.

The active EMI filtering technology provided by the embodiment of the present invention extracts differential mode electromagnetic noise and common mode electromagnetic noise from input cables of electrical equipment through the electromagnetic noise processing network 21, and then inputs them to the electromagnetic noise conversion network 22 for gain. And closed-loop feedback processing, the processed differential mode electromagnetic noise and common mode electromagnetic noise are returned to the electrical equipment through the differential mode circuit in the differential mode electromagnetic noise injection network 23 and the common mode circuit in the common mode electromagnetic noise injection network 25, respectively. Sources of differential and common mode noise in. In this way, the internal circulation of electromagnetic noise can be realized, so that the electromagnetic noise of the electrical equipment does not even enter the power supply system, so that the surrounding environment and the power supply grid are not affected by the electromagnetic noise of the electrical equipment, and the electrical equipment can also meet the EMI. Requirements for regulatory limits.

The active EMI filtering technology provided by the embodiments of the present invention has the following key innovations:

1. The electromagnetic noise processing network 21 proposed in the embodiment of the present invention adopts an independent differential mode electromagnetic noise extraction network, and outputs it to the subsequent electromagnetic noise conversion network 22 for gain and closed-loop feedback processing. The embodiment of the present invention proposes various forms of differential mode electromagnetic noise extraction networks to cooperate with the subsequent-stage electromagnetic noise conversion network 22 and the differential mode electromagnetic noise injection network 23.

The differential mode electromagnetic noise processing network provided by the embodiment of the present invention can achieve an isolation degree of greater than 60 dB from the common mode electromagnetic noise, which is equivalent to less than 0.1% of the extracted common mode electromagnetic noise from the common mode electromagnetic noise, so that the electromagnetic noise suppression can reach Expected suppression effect.

2. The electromagnetic noise processing network 21 proposed in the embodiment of the present invention adopts an independent common mode electromagnetic noise extraction network, and outputs it to the subsequent electromagnetic noise conversion network 22 for gain and closed-loop feedback processing.

The embodiments of the present invention propose various forms of common-mode electromagnetic noise extraction networks to cooperate with the subsequent-stage electromagnetic noise conversion network 22 and the common-mode electromagnetic noise injection network 25. The common-mode electromagnetic noise extraction network provided by the embodiment of the present invention can achieve an isolation degree of greater than 60 dB from differential-mode electromagnetic noise, which is equivalent to less than 0.1% of the extracted common-mode electromagnetic noise. To achieve the desired suppression effect.

3. The active EMI filter proposed in the embodiment of the present invention uses an independent differential mode noise injection network 23 to inject the processed differential mode electromagnetic noise into the differential mode circuit of the electrical equipment, and by changing the differential mode in the differential mode circuit Impedance to suppress differential mode electromagnetic noise. The embodiment of the present invention proposes multiple forms of differential mode electromagnetic noise injection network 23, which injects the differential mode electromagnetic noise after the pre-processing into the differential mode circuit of the electrical equipment, and realizes this by changing the differential mode impedance in the differential mode circuit. Suppression of electromagnetic noise.

4. The active EMI filter proposed in the embodiment of the present invention uses an independent common-mode noise injection network 25 to inject the processed common-mode electromagnetic noise into the common-mode loop of the electric equipment and then return to the common-mode circuit in the electric equipment. Mode noise source, forming an internal loop. The embodiment of the present invention proposes various forms of common-mode electromagnetic noise injection network 25, injects the common-mode electromagnetic noise after the pre-processing into the common-mode loop of the electric equipment, and then returns to the common-mode noise source in the electric equipment. An internal cycle is formed to suppress electromagnetic noise.

5. The active EMI filter provided by the embodiment of the present invention has the flexibility of the differential mode electromagnetic noise injection point, and can inject the differential mode electromagnetic noise at any point from the input cable to the differential mode circuit in the subsequent-stage electrical equipment. , By changing the differential mode impedance in the differential mode circuit, the suppression effect of electromagnetic noise is realized.

6. The active EMI filter provided by the embodiment of the present invention has the flexibility of a common-mode electromagnetic noise injection point, and the common-mode electromagnetic injection can be performed at any point from the input cable to the common-mode circuit in the subsequent-stage electrical equipment. Noise, and then return to the common mode electromagnetic noise source in the electrical equipment, forming an internal cycle to achieve the suppression of electromagnetic noise.

In the following, various forms of electromagnetic noise processing network 21, differential mode electromagnetic noise injection network 23, common mode electromagnetic noise injection network 25, and flexible electromagnetic noise injection points according to the embodiments of the present invention are described one by one.

The following are various implementations of the electromagnetic noise processing network 21.

The electromagnetic noise processing network 21 used in the active EMI filter provided by the embodiment of the present invention includes an electromagnetic noise extraction network. The electromagnetic noise extraction network has the following two main implementation modes: a direct extraction network and an indirect extraction network, or correspondingly called Single-stage extraction network and two-stage extraction network are used to extract differential mode electromagnetic noise and common mode electromagnetic noise.

The electromagnetic noise extraction network includes a common-mode electromagnetic noise extractor and a differential-mode electromagnetic noise extractor. The common-mode electromagnetic noise extractor is used to extract and output the common-mode electromagnetic noise of the input cable. To extract and output the differential mode electromagnetic noise of the input cable.

In a single-stage extraction network, a common-mode electromagnetic noise extractor is used to directly extract and output common-mode electromagnetic noise of an input cable; a differential-mode electromagnetic noise extractor is used to directly extract and output differential-mode electromagnetic noise of an input cable.

In the two-stage extraction network, the common mode electromagnetic noise extractor is used to indirectly extract and output the common mode electromagnetic noise of the input cable; the differential mode electromagnetic noise extractor is used to indirectly extract and output the differential mode electromagnetic noise of the input cable.

FIG. 8 is a schematic diagram when the electromagnetic noise processing network provided by the embodiment of the present invention is a unipolar extraction network. As shown in FIG. 8, the single-stage extraction network includes a common mode electromagnetic noise extractor 211 and a differential mode electromagnetic noise extractor 212. In some embodiments, the common mode electromagnetic noise extractor 211 and the differential mode electromagnetic noise extractor 212 are both current transformers. The first input cable 11 passes through the inner ring of the common mode electromagnetic noise extractor 211 and the differential mode electromagnetic noise extractor 212 in order, and is then connected to the power consumption device; the second input cable 12 passes through the common mode electromagnetic noise extractor 211 After the inner ring of the ring, surround the ring body of the differential mode electromagnetic noise extractor 212 around the ring body in the thickness direction of the differential mode electromagnetic noise extractor 212, and then loop out, and then connect it to the electric equipment.

Since the first input cable 11 and the second input cable 12 pass through the inner loop of the common mode electromagnetic noise extractor 211 at the same time, according to the current loop law, the output current of the common mode electromagnetic noise extractor 211 is equal to The sum of the currents of the two input cables. Since I _{input 1} + I _{input 2} = (I _CM / 2 + I _DM ) + (I _CM / 2-I _DM ) = I _CM , the output current of the common mode electromagnetic noise extractor 211 is a common mode electromagnetic noise current I _CM .

For differential mode electromagnetic noise extractor 212, according to the direction of current flowing in the direction of the cable and the inner ring of the input cable, the electromagnetic noise can be obtained differential mode output current extractor 212 is: I _{input 1--} I _{input 2} = (I _CM / 2 + I _DM )-(I _CM / 2-I _DM ) = I _DM . That is, the output current of the differential mode electromagnetic noise extractor 212 is the differential mode electromagnetic noise current I _DM .

The common-mode electromagnetic noise current I _CM output by the common-mode electromagnetic noise extractor 211 and the differential-mode electromagnetic noise current I _DM output by the differential-mode electromagnetic noise extractor 212 are output to the next-stage electromagnetic noise conversion network 22 to perform gain and Closed-loop feedback processing.

FIG. 9 is a schematic diagram when the electromagnetic noise processing network provided by the embodiment of the present invention is a two-stage extraction network. As shown in FIG. 9, the two-stage extraction network includes an electromagnetic noise sampler 213 and a differential common-mode electromagnetic noise extraction network 214. The electromagnetic noise sampler 213 is disposed between the input cable and the differential common-mode electromagnetic noise extraction network 214. The electromagnetic noise sampler 213 is configured to sample the differential common mode electromagnetic noise of the input cable and output the sampled differential common mode electromagnetic noise to the differential common mode electromagnetic noise extraction network 214.

The differential common-mode electromagnetic noise extraction network 214 is equivalent to the unipolar extraction network in the embodiment shown in FIG. 8, and includes a common-mode electromagnetic noise extractor 211 and a differential-mode electromagnetic noise extractor 212. The common mode electromagnetic noise extractor 211 is used to extract and output the common mode electromagnetic noise of the differential common mode electromagnetic noise sampled by the electromagnetic noise sampler 213, such as the common mode component of the electromagnetic noise shown in FIG. 9; the differential mode electromagnetic noise extraction The generator 212 is used for extracting and outputting the differential mode electromagnetic noise of the differential common mode electromagnetic noise sampled by the electromagnetic noise sampler 213, such as the electromagnetic noise differential mode component shown in FIG.

The electromagnetic noise sampler 213 extracts the overall electromagnetic noise on each input cable, and then inputs it to the differential common-mode electromagnetic noise extraction network 214. The differential common-mode electromagnetic noise extraction network 214 separates the common-mode electromagnetic noise and the differential-mode electromagnetic noise, and then outputs them to the lower-level electromagnetic noise conversion network 22 for gain and closed-loop feedback processing. The total electromagnetic noise on each input cable includes differential mode electromagnetic noise and common mode electromagnetic noise.

The electromagnetic noise sampler 213 can sample the overall electromagnetic noise in each input cable in a variety of ways. The multiple implementations of the electromagnetic noise sampler 213 can be arbitrarily combined with the multiple implementations of the post-differential common-mode electromagnetic noise extraction network 214 according to the actual application needs to obtain more pure differential-mode electromagnetic noise and common-mode electromagnetic noise. As an input to the subsequent-stage electromagnetic noise conversion network 22.

In the embodiment of the present invention, the electromagnetic noise sampler 213 can be implemented in two ways.

FIG. 10 is a schematic diagram of a first implementation manner of an electromagnetic noise sampler according to an embodiment of the present invention. Referring to FIG. 10, in a first implementation manner, the electromagnetic noise sampler 213 includes a first sampler 215 and a second sampler 216. The first sampler 215 is disposed on the first input cable 11, and the first sampler 215 is connected to the common mode electromagnetic noise extractor 211 or the differential mode electromagnetic noise extractor 212. The second sampler 216 is disposed on the second input line. On the cable 12, the second sampler 216 is connected to the common mode electromagnetic noise extractor 211 or the differential mode electromagnetic noise extractor 212.

In some embodiments, both the first sampler 215 and the second sampler 216 may be current transformers. The current transformer samples the electromagnetic noise current on the input cable added to it, and the electromagnetic noise obtained in this way includes common mode electromagnetic noise and differential mode electromagnetic noise in the input cable.

FIG. 11 is a schematic diagram of a second implementation manner of the electromagnetic noise sampler according to an embodiment of the present invention. Referring to FIG. 11, in a second implementation manner, the electromagnetic noise sampler 213 includes an inductor L ₁ , and the inductor L ₁ includes two primary-side windings N _P1 and N _P2 and two secondary-side sampling windings N _S1 and N _S2. Among them, one primary winding N _{P1 is} connected in series between the first input cable 11 and the electrical equipment, and the other primary winding N _{P2 is} connected in series between the second input cable 12 and the electrical equipment; two The secondary sampling windings N _S1 and N _{S2 are} coupled to the two primary windings N _P1 and N _{P2 in a} one-to-one correspondence, and the two second ends of the two secondary sampling windings N _S1 and N _S2 are used to output corresponding input cables. Of common-mode electromagnetic noise.

More specifically, the electromagnetic noise sampler 213 uses an inductor and a coupled winding to obtain electromagnetic noise on each input cable. The inductor L _{1 is} composed of 4 windings, which are the primary windings N _P1 and N _P2 , and the secondary side. The sampling windings N _S1 and N _S2 , the primary winding N _P1 and the secondary sampling winding N _S1 adopt a tightly coupled winding method to achieve a high degree of coupling; the primary winding N _P2 and the secondary sampling winding N _S2 use a tightly coupled winding. Line mode to achieve high coupling.

The primary winding N _{P1 is} connected in series between the first input cable 11 and the input of the electrical equipment, and the primary winding N _{P2 is} connected in series between the second input cable 12 and the input of the electrical equipment. After one end of the secondary-side sampling windings N _S1 and N _{S2 is} grounded, the other end outputs electromagnetic noise coupled to the corresponding input cable. The electromagnetic noise obtained in this way includes common mode electromagnetic noise and differential mode electromagnetic noise in the cable.

The implementation of the differential common-mode electromagnetic noise extraction network 214 is as follows:

The differential common-mode electromagnetic noise extraction network 214 can be isolated in various forms to obtain more pure differential-mode electromagnetic noise and common-mode electromagnetic noise as the input of the subsequent-stage electromagnetic noise conversion network 22. The multiple implementations of the differential common mode electromagnetic noise extraction network 214 can refer to the multiple implementations of the previous-stage electromagnetic noise sampler 213. According to the actual application needs, any combination can be obtained to obtain more pure differential mode electromagnetic noise and common mode electromagnetic Noise is used as an input to the subsequent-stage electromagnetic noise conversion network 22.

There are two implementations of the differential common-mode electromagnetic noise extraction network 214: a winding induced voltage cancellation method and an operational amplifier algebra and method.

FIG. 12 is a first schematic diagram of an electromagnetic noise extraction network provided by an embodiment of the present invention. As shown in FIG. 12, the differential common mode electromagnetic noise extraction network 214 can be implemented by a winding induced voltage cancellation method of a magnetic device to obtain more pure differential mode electromagnetic noise and common mode electromagnetic noise. Among them, the common mode electromagnetic noise extractor and the differential mode electromagnetic noise extractor are dual-winding inductors, which are L ₁ and L _{2 respectively} . The two windings of the dual-winding inductor L _{1 used} by the common-mode electromagnetic noise extractor have opposite polarities, and the first ends of the two windings of the common-mode electromagnetic noise extractor are respectively used to receive the first input cable 11 and the first winding. two differential input cable common mode electromagnetic noise 12, the second ends of the two windings of the common mode electromagnetic noise extractor for outputting the average common mode electromagnetic noise; L two pairs of differential mode inductance coil uses electromagnetic noise extraction ₂ The windings have the same polarity. The first ends of the two windings of the differential mode electromagnetic noise extractor are used to receive the differential common mode electromagnetic noise of the first input cable 11 and the second input cable 12, respectively. The second ends of the two windings of the dual-winding inductor L ₁ and the dual-winding inductor L ₂ used by the converter are both used to output differential mode electromagnetic noise.

First, the two ends of the two windings of the dual-winding inductor L ₁ with opposite polarities are respectively connected to the electromagnetic noise 111 of the first input cable 11 and the electromagnetic noise 121 of the second input cable 12 output by the preceding electromagnetic noise sampler 213. ; The other ends of the two windings of the dual-winding inductor L ₁ are connected as a common-mode electromagnetic noise output after being connected.

Since the common mode currents in the first input cable 11 and the second input cable 12 are in the same direction, and the differential mode currents in the first input cable 11 and the second input cable 12 are opposite to each other, so According to the magnetic principle, the induced voltages generated by the common-mode current of the first input cable 11 and the second input cable 12 in the windings of the magnetic core in the dual-winding inductor L ₁ cancel each other, in other words, the common-mode current There is no inhibiting effect, on the contrary it has inhibiting effect on the differential mode current. Therefore, the differential mode electromagnetic noise can be isolated through a connection method such as the double-winding inductor L ₁ to obtain pure common mode electromagnetic noise.

In accordance with the above-mentioned principle of isolating differential mode electromagnetic noise, common mode electromagnetic noise can also be isolated. First, the two ends of the two windings of the double-winding inductor L ₂ having the same polarity are respectively connected to the electromagnetic noise 111 of the first input cable 11 and the electromagnetic noise 121 of the second input cable 12 output by the preceding electromagnetic noise sampler 3213. ; The other ends of the two windings of the dual-winding inductor L ₂ are connected as a differential mode electromagnetic noise output after being connected.

The differential mode currents in the first input cable 11 and the second input cable 12 are opposite to each other, and the common mode currents in the first input cable 11 and the second input cable 12 are the same. Therefore, according to the magnetic principle, the induced voltages generated in the same differential mode current of the first input cable 11 and the second input cable 12 in the windings of the magnetic core in the dual winding inductance L ₂ cancel each other. In other words, the differential mode The current has no inhibitory effect, and conversely it has a suppressive effect on the common mode current. Therefore, the common mode electromagnetic noise can be isolated through a connection method such as the double-winding inductor L ₂ to obtain pure differential mode electromagnetic noise.

FIG. 13 is a second schematic diagram of an electromagnetic noise extraction network provided by an embodiment of the present invention. As shown in FIG. 13, the differential common-mode electromagnetic noise extraction network 214 can also be implemented by a logarithmic sum of operational amplifiers to obtain more pure differential-mode electromagnetic noise and common-mode electromagnetic noise.

Common mode electromagnetic noise output by the first operational amplifier 33, a first resistor R _1, a second resistor R _2, R ₃ of the third resistor and the fourth resistor R ₄ to achieve the object of the differential mode electromagnetic noise isolation. A first operational amplifier 33 and the negative input terminal of resistor R _1, R ₂ and R ₃ are connected, is connected to the positive input terminal of the first operational amplifier 33 and the fourth resistor R _4, is connected to the ground via the fourth resistor R _4; the first An output terminal of an operational amplifier 33 is connected to the third resistor R ₃ and is also used as a common-mode electromagnetic noise component output terminal 108. The other end of the first resistor R ₁ is connected to the electromagnetic noise 111 of the first input cable 11; a second resistor R The other end of ₂ is connected to the electromagnetic noise 121 of the second input cable 12. Can be achieved according to algebraic summer connected to the operational amplifier and resistor network embodiment, the input cable of the first electromagnetic noise current I _input 11 of the cable ₁ and the second input 12 of the electromagnetic noise current I _input algebraically adding ₂ I ₁ + I _{input Input 2 to} get the common mode electromagnetic noise I _{CM in this way} and isolate the differential mode electromagnetic noise I _DM .

According to the method for obtaining common-mode electromagnetic noise described above, subtraction can also be implemented to obtain differential-mode electromagnetic noise, while isolating common-mode electromagnetic noise.

Differential output mode by the second electromagnetic noise operational amplifier 34, a fifth resistor R _5, the sixth resistor R _6, R ₇ seventh resistor and an eighth resistor R ₈ to achieve the objectives of common mode electromagnetic noise isolation. The negative input terminal of the second operational amplifier 34 is connected to the fifth resistor R ₅ and the seventh resistor R ₇ ; the positive input terminal of the second operational amplifier 34 is connected to the sixth resistor R ₆ and the eighth resistor R ₈ . R ₈ is connected to the ground; the output terminal of the second operational amplifier 34 is connected to the seventh resistor R ₇ and at the same time serves as the differential mode electromagnetic noise component output terminal 109; the other end of the fifth resistor R ₅ is connected to the electromagnetic of the first input cable 11 The noise 111 is connected; the other end of the sixth resistor R ₆ is connected to the electromagnetic noise 121 of the second input cable 12.

The connector may be implemented algebraically embodiment of the operational amplifier and resistor network, the first input 11 of the cable electromagnetic noise current I _input and _a second input 12 of the cable electromagnetic noise current I _{input 2 input} I ₁ -I algebraically _{Enter 2} to get the differential mode electromagnetic noise I _DM and isolate the common mode electromagnetic noise I _CM .

The implementation method of the "algebraic sum of operational amplifiers" described above is one of the implementation methods of realizing algebraic addition and subtraction of common mode electromagnetic noise and differential mode electromagnetic noise in an input cable.

Among them, + Vcc and -Vcc referred to in the drawings of this embodiment represent a positive power source and a negative power source, respectively.

The following are various implementations of the differential mode electromagnetic noise injection network 23.

The differential mode electromagnetic noise injection network 23 can be implemented in a variety of ways, including: in the form of a semiconductor transistor and a differential mode inductor.

FIG. 14 is a schematic diagram of a differential mode electromagnetic noise injection network based on a semiconductor transistor according to an embodiment of the present invention. Referring to FIG. 14, in the differential mode electromagnetic noise injection network 23 based on a semiconductor transistor, the semiconductor transistor is a field effect transistor Q ₁ whose drain is connected to the first input cable 11 and whose source is connected to an electrical device. Its gate is connected to the differential-mode electromagnetic noise component output terminal 109 of the preceding-stage electromagnetic noise conversion network 22.

Active EMI filter according to embodiments of the present invention can be made by using the gate voltage of the transistor Q ₁ 'changes by adjusting the first input differential-mode impedance on the cable 11, in order to achieve the purpose of suppressing electromagnetic noise in differential mode.

Since the first input cable 11 and the second input cable 12 are in the same differential mode circuit, the transistor Q ₁ can be placed at any position in the differential mode circuit, and the purpose of suppressing the differential mode electromagnetic noise can be achieved. For example, it is placed on the second input cable 12 or in the differential mode circuit of the subsequent-stage electrical equipment.

FIG. 15 is a schematic diagram of a differential mode electromagnetic noise injection network based on a dual-winding differential mode inductor according to an embodiment of the present invention. Referring to FIG. 15, in the differential-mode electromagnetic noise injection network 23 based on the dual-winding differential-mode inductance, the differential-mode inductance L ₃ has two windings: a primary winding N _P and a secondary winding N _S ; and a dual-winding differential mode inductor. One end of the primary winding N _{P of} L ₃ is connected to the differential mode electromagnetic noise component output terminal 109 of the previous-stage electromagnetic noise conversion network 22, and the other end is grounded; one end of the secondary winding N _S of the dual-winding differential mode inductor L ₃ is connected to the first One input cable 11 and the other end are connected to the subsequent-stage electrical equipment.

Active EMI filter according to embodiments of the present invention can be made using a dual winding differential mode inductance L of the primary winding N _{P 3} of the preceding stage differential mode components of electromagnetic noise is coupled to the switching network 22 L double secondary winding ₃ of the differential mode inductance In the differential mode circuit where the winding N _S is located, the differential mode impedance of the differential mode circuit is changed, thereby achieving the purpose of suppressing the differential mode noise.

FIG. 16 is a schematic diagram of a differential mode electromagnetic noise injection network based on a three-winding differential mode inductor according to an embodiment of the present invention. As shown in FIG. 16, in a three-mode differential mode electromagnetic noise injection network based on a three-winding differential mode inductor, the three-window differential mode inductor L ₄ has three windings: a primary winding N _P1 , a first secondary winding N _S1, and a second winding. The secondary winding N _S2 ; one end of the primary winding N _{P1 of the} three-winding differential mode inductor L ₄ is connected to the differential mode electromagnetic noise component output terminal 109 of the preceding-stage electromagnetic noise conversion network 22, and the other end is grounded; the three-winding differential mode inductor L ₄ of the first secondary winding N _S1 first input end of a cable 11, the other end of the electricity device; three-winding differential mode inductance L ₄ of the second secondary winding N _S2 second input line connected at one end Cable 12, the other end is connected to the post-stage electrical equipment.

The active electromagnetic interference filter proposed in the embodiment of the present invention can use the primary winding N _P1 of the three-winding differential mode inductor L ₄ to couple the differential-mode electromagnetic noise component output terminal 109 of the previous-stage electromagnetic noise conversion network 22 to the three-winding differential mode. In the differential mode circuit where the first secondary winding N _S1 and the second secondary winding N _S2 of the inductor L ₄ are located, the differential mode impedance of the differential mode circuit is changed, thereby achieving the purpose of suppressing differential mode noise.

The following is an implementation manner of the common mode noise injection network 25.

The common mode noise injection network 25 can also be implemented in a variety of ways, including: a capacitor-based common mode noise injection network 25, a grounded capacitor-based common mode noise injection network 25, and a common mode inductance based common mode noise injection network 25.

FIG. 17 is a schematic diagram of a capacitor-based common mode electromagnetic noise injection network according to an embodiment of the present invention. Referring to FIG. 17, based on the capacitance common mode noise injected into the network 25, the first capacitance C _1, C _2, and a second capacitor end of the third capacitor C ₃ connected together; the other terminal of the first capacitor C ₁ and The first input cable 11 is connected to the subsequent-stage electrical equipment, and the other end of the second capacitor C ₂ is connected to the second input cable 12 and the subsequent-stage electrical equipment; the other end of the third capacitor C ₃ is connected to the previous-stage electromagnetic noise The common-mode electromagnetic noise component output terminal 108 of the conversion network 22 is connected.

The active EMI filter proposed in the embodiment of the present invention can inject the common-mode electromagnetic noise component output terminal 108 of the previous-stage electromagnetic noise conversion network 22 to the common capacitor through the first capacitor C ₁ , the second capacitor C _2, and the third capacitor C _3. In the mode loop, the common-mode current is returned to the subsequent-stage electrical equipment, and the purpose of suppressing the common-mode electromagnetic noise is achieved, and at the same time, the EMI receiver can detect a small amount, or even the common-mode noise.

The connection method of the capacitor-based common-mode noise injection network 25 does not need to involve earth, so it can be applied not only to Class I electrical equipment with input ground, but also to Class II electrical equipment without input to ground, and DC power supply. Power equipment.

FIG. 18 is a schematic diagram of a common mode electromagnetic noise injection network based on a ground capacitor according to an embodiment of the present invention. Referring to FIG. 18, in the common mode noise injection network 25 based on the ground capacitor, one end of the fourth capacitor C ₄ is connected to the common mode electromagnetic noise component output terminal 108 of the previous-stage electromagnetic noise conversion network 22, and the other end is connected to the ground or The enclosure of an electric device.

The active EMI filter proposed in the embodiment of the present invention can inject the common mode output component of the previous-stage electromagnetic noise conversion network 22 into the common mode noise loop through the fourth capacitor C ₄ , so that the common mode electromagnetic noise returns to the common mode noise source as soon as possible. , Can be small or even not detected by the EMI receiver common mode noise.

FIG. 19 is a schematic diagram of a common mode electromagnetic noise injection network based on common mode electromagnetic according to an embodiment of the present invention. Referring to FIG. 19, in a common mode noise injection network 25 based on a common mode inductor, the common mode inductor L ₅ has three windings: a primary winding N _P1 , a first secondary winding N _S1, and a second secondary winding N _S2. . One end of the primary winding N _P1 of the common mode inductor L ₅ is connected to the common mode electromagnetic noise component output terminal 108 of the previous-stage electromagnetic noise conversion network 22, and the other end is grounded; one end of the first secondary winding N _{S1 of the} common mode inductor L ₅ is connected To the first input cable 11, the other end is connected to the power consumption equipment; one end of the second secondary winding N _S2 of the common mode inductor L ₅ is connected to the second input cable 12, and the other end is connected to the power consumption equipment.

Active EMI filter according to the embodiment of the present invention can be made by the primary winding L N _P 1 before the common mode component of the output stage switching network 22 of an electromagnetic noise of the inductor _5, the inductance L of the secondary winding N ₅ and N _{Sl S2 is} injected into the common mode noise loop to cancel the common mode current in the common mode loop, which can reduce the common mode noise detected by the EMI receiver.

The injection point of the differential mode electromagnetic noise injection network 23 proposed in the embodiment of the present invention may be any position in the differential mode loop, and the suppression effect of the differential mode electromagnetic noise can be achieved. The differential mode circuit mentioned in the embodiments of the present invention refers to the components, circuits, and input cables inside the electrical equipment through which the differential mode current I _DM flows.

FIG. 20 is a simplified circuit diagram of an AC input power adapter according to an embodiment of the present invention. Referring to FIG. 20, the loop indicated by the black arrow is a differential mode loop through which the differential mode current I _DM flows, from the hot line L, the rectifier bridge BD1, the capacitor C ₁ to the neutral line N, and also includes the connection between the devices. In the embodiment of the present invention, the injection point of differential mode electromagnetic noise can be selected from the four points indicated by A, B, C, and D in the circuit shown in FIG. 20, where point A is the live line L and point B is the rectifier bridge. BD1 positive connection of the capacitor C _1, C point bridge rectifier BD1 and a negative electrode connecting capacitor C _1, D line zero point N.

When the differential mode electromagnetic noise injection network 23 of the three-winding differential mode inductor is used for the injection of the differential mode electromagnetic noise, two points A / D can be considered as the insertion points of the two secondary windings of the three-winding differential mode inductor, or B / C Two points are used as the insertion points of the two secondary windings of the three-winding differential mode inductor.

FIG. 21 is a simplified circuit diagram of a DC input switching power supply according to an embodiment of the present invention. Referring to FIG. 21, the loop indicated by the black arrow is a differential mode loop through which the differential mode current I _DM flows. The differential mode circuit is connected from the positive input terminal, and the capacitor C _{1 is} connected to the negative input terminal. The injection point of the differential mode electromagnetic noise proposed in the embodiment of the present invention can be selected from points A and B for injection in FIG. 21. Point A is the line connecting the positive input, and point B is the line connecting the negative input.

When the differential mode electromagnetic noise injection network 23 of the three-winding differential mode inductor is used for the differential mode electromagnetic noise injection, two points A / B can be considered as the insertion points of the two secondary windings of the three-winding differential mode inductor.

The injection point of the common-mode electromagnetic noise injection network 25 can be at any position in the common-mode loop, and the suppression effect of the common-mode electromagnetic noise can be achieved. The common mode circuit mentioned in the present invention refers to the devices, circuits, input cables and ground inside the electric equipment through which the common mode current I _CM flows.

FIG. 22 is a simplified circuit diagram of an AC input power adapter according to an embodiment of the present invention. Referring to FIG. 22, a black arrow indicates a common mode loop through which a common mode current I _CM flows. Common mode loop from the firing line L, neutral line N, bridge rectifier BD1 positive connection of the capacitor C _1, the bridge rectifier BD1 and a negative electrode connecting capacitor C _1, the drain of the transistor Q ₁ ', and the drain of the parasitic capacitance of the earth C _sent into the earth; another common mode loop from the transformer connected to the anode of the rectifier diode and the parasitic capacitance C of the earth _{to send,} into the earth.

The injection points of the common-mode electromagnetic noise injection network 25 according to the embodiment of the present invention can be selected from points A, B, C, and D. Unlike the differential-mode electromagnetic noise injection network 23, a single point can be selected for injection. The common-mode electromagnetic noise injection network 25 can be selected. The injection point must be selected for paired injection. When the capacitor-based common-mode electromagnetic noise injection network 25 shown in FIG. 17 is used, points A and B must be selected as the connection points of the capacitor C ₁ and the capacitor C ₂ at the same time. Similarly, when a common-mode electromagnetic noise injection network 25 using a three-winding common-mode inductor is used, the secondary windings of the common-mode inductor must be inserted at points A and B at the same time.

FIG. 23 is a simplified circuit diagram of a DC input switching power supply according to an embodiment of the present invention. Referring to FIG. 23, a loop indicated by a black arrow is a common mode loop through which a common mode current I _CM flows. The common mode circuit is from the connection between the input positive electrode and the capacitor C ₁ , the connection between the input negative electrode and the capacitor C ₁ , the connection between the capacitor C ₁ and the drain of the transistor Q ₁ , and the connection between the capacitor C ₁ and the source of the transistor Q ₂ . transistor Q ₁ and the transistors Q ₂ and the midpoint of the bridge arm of the parasitic capacitance C between the earth _{to send,} the parasitic capacitance C between the transistor Q ₃ and the transistor Q ₄ and the midpoint of the bridge arm _send earth, between the transformer T _1, transformer T ₁ and the ground The parasitic capacitance C is _{sent to the} ground as well.

The injection points of the common-mode electromagnetic noise injection network 25 according to the embodiment of the present invention can be selected from points A, B, C, and D. Unlike the differential-mode electromagnetic noise injection network 23, a single point can be selected for injection. The common-mode electromagnetic noise injection network 25 can be selected. The injection point must be selected for paired injection. When a capacitor-based common-mode electromagnetic noise injection network 25 is used, point A and point B must be selected as the connection points of capacitor C ₁ and capacitor C ₂ at the same time. Similarly, when a common-mode electromagnetic noise injection network 25 based on a three-winding common-mode inductor is used, the secondary windings of the common-mode inductor must be inserted at points A and B at the same time.

FIG. 24 is a schematic diagram of an electromagnetic noise conversion network according to an embodiment of the present invention. Referring to FIG. 8 to FIG. 24, the main function of the electromagnetic noise conversion network 22 according to the embodiment of the present invention is to amplify and close-loop feedback processing the differential mode electromagnetic noise and common mode electromagnetic noise output by the previous-stage electromagnetic noise processing network 21. It is then output to the differential-mode electromagnetic noise injection network 23 and the common-mode electromagnetic noise injection network 25 at the subsequent stage. The electromagnetic noise conversion network 22 may use an operational amplifier, a first resistance-capacitance network 35 and a second resistance-capacitance network 36 to implement gain amplification and closed-loop feedback. The electromagnetic noise conversion network 22 may perform gain adjustment and phase adjustment by adjusting resistance and capacitance values in the first resistance-capacitance network 35 and the second resistance-capacitance network 36 to achieve the gain and phase required to suppress electromagnetic noise.

Various forms of electromagnetic noise extraction network 22, differential mode noise injection network 23, common mode noise injection network 25 and the injection points of the processed differential mode electromagnetic noise and common mode electromagnetic noise proposed in the embodiments of the present invention can be performed according to actual application requirements. random combination.

The active EMI filtering technology provided by the embodiment of the present invention is not only applicable to an AC power supply system, but also applicable to a DC power supply system.

The active EMI filtering technology provided by the embodiment of the present invention is applicable to Class I electrical equipment with a ground wire input, and also applicable to Class II electrical equipment without a ground wire input.

Example one

FIG. 25 is a schematic diagram of an active electromagnetic interference filter according to the first embodiment of the present invention. Referring to FIG. 25, a first embodiment of the present invention proposes an active electromagnetic interference filter. The first embodiment extracts electromagnetic noise generated by an electrical equipment through an electromagnetic noise processing network 21 to obtain differential mode electromagnetic noise and common mode electromagnetic noise, respectively. After passing through the two electromagnetic noise conversion networks 22 for gain and closed-loop feedback processing, the differential mode electromagnetic noise injection network 23 passes the processed differential mode electromagnetic noise through the differential mode loop to offset the subsequent stage electrical equipment in the differential mode loop. The generated differential mode noise, and at the same time, the processed common mode electromagnetic noise is returned to the common mode noise source in the electric equipment through the common mode loop through the common mode electromagnetic noise injection network 25, thereby realizing the internal circulation mode of electromagnetic noise and satisfying electromagnetic interference. The requirements of (EMI) regulatory limits make the power supply system and the surrounding environment unaffected by electromagnetic noise generated by electrical equipment.

The electromagnetic noise processing network 21 in Embodiment 1 of the present invention is composed of two current transformers, and respectively obtains a differential mode current I _DM generated by differential mode electromagnetic noise and a common mode current I _CM generated by common mode electromagnetic noise.

The differential mode electromagnetic noise injection network 23 in the first embodiment of the present invention adopts a semiconductor mode-based differential mode electromagnetic noise injection network; the common mode electromagnetic noise injection network 25 in the first embodiment of the present invention uses a capacitor-based common mode electromagnetic noise injection network. .

Example two

FIG. 26 is a schematic diagram of an active electromagnetic interference filter according to a second embodiment of the present invention. Referring to FIG. 26, a second embodiment of the present invention proposes an active electromagnetic interference filter. The electromagnetic noise generated by the electrical equipment is extracted through the electromagnetic noise processing network 21 to obtain a differential mode electromagnetic noise and a common mode electromagnetic noise, respectively. After the two electromagnetic noise conversion networks 22 perform gain and closed-loop feedback processing, the differential mode electromagnetic noise injection network 23 passes the processed differential mode electromagnetic noise through the differential mode loop to offset the difference generated by the subsequent stage electrical equipment in the differential mode loop. Mode noise, and at the same time, the common mode electromagnetic noise injection network 25 is used to return the processed common mode electromagnetic noise to the common mode noise source in the electrical equipment through the common mode loop, thereby realizing the internal circulation of electromagnetic noise to meet electromagnetic interference (EMI) The requirements of the regulatory limits make the power supply system and the surrounding environment unaffected by the electromagnetic noise generated by electrical equipment.

The electromagnetic noise processing network 21 in the second embodiment of the present invention is composed of an electromagnetic noise sampler 213 and a differential common-mode electromagnetic noise extraction network 214. Among them, the electromagnetic noise sampler 213 performs sampling through a current transformer. The differential common-mode electromagnetic noise extraction network 214 uses a magnetic cancellation method to extract differential-mode electromagnetic noise and common-mode electromagnetic noise.

The differential mode electromagnetic noise injection network 23 in the second embodiment of the present invention uses a semiconductor transistor-based differential mode electromagnetic noise injection network; the common mode electromagnetic noise injection network 25 in the second embodiment of the present invention uses a capacitor-based common mode electromagnetic noise injection network. .

Example three

FIG. 27 is a schematic diagram of an active electromagnetic interference filter according to a third embodiment of the present invention. Referring to FIG. 27, an active electromagnetic interference filter according to the third embodiment of the present invention extracts electromagnetic noise generated by electrical equipment through an electromagnetic noise processing network 21 to obtain differential mode electromagnetic noise and common mode electromagnetic noise, respectively, and then After the two electromagnetic noise conversion networks 22 perform gain and closed-loop feedback processing, the differential mode electromagnetic noise injection network 23 passes the processed differential mode electromagnetic noise through the differential mode loop to offset the electricity generated by the subsequent stage electrical equipment in the differential mode loop. Differential mode noise, and at the same time, the processed common mode electromagnetic noise is returned to the common mode noise source in the electrical equipment through the common mode loop through the common mode electromagnetic noise injection network 25, thereby realizing the internal circulation mode of electromagnetic noise to meet electromagnetic interference (EMI ) The requirements of regulatory limits make the power supply system and the surrounding environment unaffected by the electromagnetic noise generated by electrical equipment.

The electromagnetic noise processing network 21 in the third embodiment of the present invention is composed of an electromagnetic noise sampler 213 and a differential common-mode electromagnetic noise extraction network 214. Among them, the electromagnetic noise sampler 213 performs sampling through a current transformer, and the difference common mode electromagnetic noise extraction network 214 is implemented by an algebraic sum of operational amplifiers.

The differential mode electromagnetic noise injection network 23 in the third embodiment of the present invention uses a semiconductor transistor-based differential mode electromagnetic noise injection network; the common mode electromagnetic noise injection network 25 in the third embodiment of the present invention uses a capacitor-based common mode electromagnetic noise injection network. .

Example 4

FIG. 28 is a schematic diagram of an active electromagnetic interference filter according to a fourth embodiment of the present invention. Referring to FIG. 28, an active electromagnetic interference filter according to the fourth embodiment of the present invention extracts electromagnetic noise generated by electrical equipment through an electromagnetic noise processing network 21 to obtain differential mode electromagnetic noise and common mode electromagnetic noise, respectively, and then After the two electromagnetic noise conversion networks 22 perform gain and closed-loop feedback processing, the differential mode electromagnetic noise injection network 23 passes the processed differential mode electromagnetic noise through the differential mode loop to offset the electricity generated by the subsequent stage electrical equipment in the differential mode loop. Differential mode noise, and at the same time, the processed common mode electromagnetic noise is returned to the common mode noise source in the electrical equipment through the common mode loop through the common mode electromagnetic noise injection network 25, thereby realizing the internal circulation mode of electromagnetic noise to meet electromagnetic interference (EMI ) The requirements of regulatory limits make the power supply system and the surrounding environment unaffected by the electromagnetic noise generated by electrical equipment.

The electromagnetic noise processing network 21 in the fourth embodiment of the present invention is composed of an electromagnetic noise sampling network 213 and a differential common-mode electromagnetic noise extraction network 214. The electromagnetic noise sampler 213 performs sampling through an inductor, and the differential common-mode electromagnetic noise extraction network 214 is implemented by an algebraic sum of operational amplifiers.

The differential mode electromagnetic noise injection network 23 in the fourth embodiment of the present invention uses a semiconductor transistor-based differential mode electromagnetic noise injection network; the common mode electromagnetic noise injection network 25 in the fourth embodiment of the present invention uses a capacitor-based common mode electromagnetic noise injection network. .

Example 5

FIG. 29 is a schematic diagram of an active electromagnetic interference filter according to Embodiment 5 of the present invention. Referring to FIG. 29, an active electromagnetic interference filter according to the fifth embodiment of the present invention extracts electromagnetic noise generated by electrical equipment through an electromagnetic noise processing network 21 to obtain differential mode electromagnetic noise and common mode electromagnetic noise, respectively. After the two electromagnetic noise conversion networks 22 perform gain and closed-loop feedback processing, the differential mode electromagnetic noise injection network 23 passes the processed differential mode electromagnetic noise through the differential mode loop to offset the electricity generated by the subsequent stage electrical equipment in the differential mode loop. Differential mode noise, and at the same time, the processed common mode electromagnetic noise is returned to the common mode noise source in the electrical equipment through the common mode loop through the common mode electromagnetic noise injection network 25, thereby realizing the internal circulation mode of electromagnetic noise to meet electromagnetic interference (EMI ) The requirements of regulatory limits make the power supply system and the surrounding environment unaffected by the electromagnetic noise generated by electrical equipment.

The electromagnetic noise processing network 21 in the fifth embodiment of the present invention is composed of an electromagnetic noise sampler 213 and a differential common-mode electromagnetic noise extraction network 214. Among them, the electromagnetic noise sampler 213 performs sampling through a current transformer, and the difference common mode electromagnetic noise extraction network 214 is implemented by an algebraic sum of operational amplifiers.

The differential mode electromagnetic noise injection network 23 in the fifth embodiment of the present invention uses a differential mode electromagnetic noise injection network based on a dual-winding differential mode inductance; the common mode electromagnetic noise injection network 25 in the fifth embodiment of the present invention uses a common mode inductance based common Mode electromagnetic noise is injected into the network.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. range.

Claims (7)

1. A common-mode electromagnetic noise extraction network, characterized in that it includes an input cable, an electromagnetic noise sampler, and a common-mode electromagnetic noise extractor suitable for connecting between a power supply system and an electric equipment;

   The electromagnetic noise sampler is disposed between the input cable and the common mode electromagnetic noise extractor, and is configured to sample the differential common mode electromagnetic noise of the input cable and sample the differential common mode electromagnetic noise. Noise output to the common mode electromagnetic noise extractor;

   The common mode electromagnetic noise extractor is used to extract and output the common mode electromagnetic noise among the differential common mode electromagnetic noise sampled by the electromagnetic noise sampler.
2. The common mode electromagnetic noise extraction network according to claim 1, wherein the input cable comprises a first input cable and a second input cable connected in parallel;

   The electromagnetic noise sampler includes a first sampler and a second sampler; wherein,

   The first sampler is disposed on the first input cable, and the first sampler is connected to the common mode electromagnetic noise extractor;

   The second sampler is disposed on the second input cable, and the second sampler is connected to the common mode electromagnetic noise extractor.
3. The common mode electromagnetic noise extraction network according to claim 1, wherein the input cable comprises a first input cable and a second input cable connected in parallel;

   The electromagnetic noise sampler includes an inductor, and the inductor includes two primary windings and two secondary sampling windings;

   Two of the primary windings and two of the secondary sampling windings are coupled in a one-to-one correspondence;

   One of the primary windings is connected in series between the first input cable and the electrical equipment, and the other primary winding is connected in series between the second input cable and the electrical equipment;

   Both first ends of the two secondary sampling windings are connected to ground, and both second ends of the two secondary sampling windings are used to output differential common mode electromagnetic noise corresponding to the input cable.
4. The common mode electromagnetic noise extraction network according to claim 1, wherein the input cable comprises a first input cable and a second input cable connected in parallel;

   The common mode electromagnetic noise extractor includes a dual winding inductor; wherein,

   The two windings in the dual-winding inductor have opposite polarities, and the first ends of the two windings are respectively used to receive differential common mode electromagnetic noise of the first input cable and the second input cable, The second ends of the two windings are both used to output common mode electromagnetic noise.
5. The common mode electromagnetic noise extraction network according to claim 1, wherein the input cable comprises a first input cable and a second input cable connected in parallel;

   The common mode electromagnetic noise extractor includes a first operational amplifier, a first resistor, a second resistor, a third resistor, and a fourth resistor; wherein,

   A first end of the first resistor is used to receive the differential common mode electromagnetic noise of the first input cable, and a first end of the resistor is used to receive the differential common mode electromagnetic noise of the second input cable, The second terminal of the first resistor and the second terminal of the second resistor are both connected to the negative input terminal of the first operational amplifier; the third resistor is connected to the negative input terminal of the first operational amplifier And the output terminal; the fourth resistor is connected between the positive input terminal of the first operational amplifier and ground.
6. An active electromagnetic interference filter, comprising the common mode electromagnetic noise extraction network according to any one of claims 1-5.
7. The active electromagnetic interference filter according to claim 6, further comprising an electromagnetic noise conversion network and a common mode electromagnetic noise injection network;

   The electromagnetic noise conversion network is configured to perform gain and closed-loop feedback processing on the common mode electromagnetic noise;

   The processed common-mode electromagnetic noise is returned to the electric equipment through the common-mode electromagnetic noise injection network;

   The common-mode electromagnetic noise extraction network, the electromagnetic noise conversion network, and the common-mode electromagnetic noise injection network are sequentially connected.

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