Active EMI Filter with Bidirectional Electromagnetic Interference Suppression Capability, Control Method and Medium

Abstract

The present invention relates to an active EMI filter with bidirectional electromagnetic interference suppression ability, which includes a first suppression unit and a second suppression unit. The first end of the first suppression unit is connected to the grid side, and the second end of the first suppression unit is grounded; the first end of the second suppression unit is connected to the primary side of the power converter, and the second end of the first suppression unit is grounded. In the present invention, a current transformer extracts the interference current from the bus for the active EMI filter to reconstruct the interference current; a sampling resistor converts the extracted interference current into an interference voltage for the operational amplifier to achieve voltage regulation; the operational amplifier inverts the interference voltage and adjusts the amplitude, and then uses it for interference current injection and cancellation; the injection branch converts the interference voltage output by the operational amplifier into an interference current and injects it into the bus to achieve the suppression of the interference current. The proposed bidirectional active EMI filter adopts a dual CSCC scheme, and through unity gain control, bidirectional suppression of interference can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic compatibility of power electronic devices, and particularly to an active EMI filter with bidirectional electromagnetic interference suppression capability, a control method, and a medium. Background Art

[0002] Power converters are widely used in industries, commerce, national defense and other fields, and are one of the fundamental key technical devices for scientific and technological progress and development. While a power converter operating in a switching state performs power conversion, it will generate very high du / dt and di / dt (voltage and current change rates), and generate conducted and radiated interference, affecting the normal operation of surrounding devices. The traditional method for suppressing conducted interference is to use a passive EMI filter. With the development of power converters towards high frequency and high power density, the passive EMI filter has a relatively large volume and weight, which can account for 30% - 50% of the entire power converter, and is one of the main factors affecting the integrated development of power converters. Using an active EMI filter can significantly reduce the volume and weight of the EMI filter, and is one of the key technologies for the development of high power density power converters. Currently, the research on active EMI filters mainly focuses on the suppression of unidirectional EMI with the power converter as the interference source, while traditional passive EMI filters usually have bidirectional interference suppression capabilities. In addition to suppressing the conducted interference of the power converter, they can also suppress the conducted interference and radiated coupling interference on the grid side to improve the immunity of the power converter. Therefore, the research on active EMI filters needs to further improve their EMI suppression function. Summary of the Invention

[0003] During the operation of a power converter, serious electromagnetic interference will be generated due to the high-frequency operation of power switches, which easily causes the surrounding electrical and electronic devices to fail to operate normally. The traditional method for suppressing interference is to use a passive EMI filter, but its power density is very low, occupying a large space and weight in the power converter. Under the development trend of high frequency and high power density of power converters, it is urgent to solve the problem of high volume and weight of passive EMI filters. The active EMI filter uses components with higher power density to form an active interference cancellation circuit, which can significantly improve the power density of the power converter. The traditional active EMI filter mainly focuses on the interference suppression problem on the power converter side, while the passive EMI filter actually has bidirectional interference suppression capabilities and can improve the immunity of the power converter. Therefore, the present invention proposes an active EMI filter with bidirectional interference suppression capabilities, adopts a double CSCC face-to-face structure, and uses unity gain control to achieve the suppression of bidirectional interference. While suppressing the conducted interference of the power converter, its immunity is improved.

[0004] The present invention mainly aims at the problems of low power density of passive suppression of conducted interference in power converters and the fact that current active suppression usually only has unidirectional EMI suppression ability, and proposes an active EMI filter topology and control method with bidirectional EMI suppression ability. This topology adopts a CSCC feedforward and feedback cascaded hybrid active circuit, and the control method ensures that, from the perspectives of both the converter and the grid side, it belongs to a consistent feedforward and feedback cascaded active EMI filter, thus ensuring that the proposed active EMI suppression circuit has the ability to suppress bidirectional EMI.

[0005] An active EMI filter with bidirectional electromagnetic interference suppression ability, comprising a first suppression unit and a second suppression unit. The first end of the first suppression unit is connected to the grid side, and the second end of the first suppression unit is grounded; the first end of the second suppression unit is connected to the primary side of the power converter, and the second end of the second suppression unit is grounded, where EMI is electromagnetic interference.

[0006] The first suppression unit includes a first current transformer and a first CSCC. The first current transformer is coupled to the bus, the output of the first current transformer is connected to the first end of the first CSCC, and the second end of the first CSCC is grounded; the second suppression unit includes a second current transformer and a second CSCC. The first end of the second current transformer is connected to the grid side, the second end of the second current transformer is connected to the first end of the second CSCC, and the second end of the second CSCC is grounded, where CSCC is a current detection current compensation module.

[0007] Preferably, the first CSCC includes a first sampling resistor R1, a first inverting operational amplifier component, and a first injection branch. The first end and the second end of the first sampling resistor R1 are respectively connected to the output end of the first current transformer. The first injection branch includes a first injection resistor R 1in and a first injection capacitor C 1in . The first end of the first injection resistor R 1in is connected to the first end of the first inverting operational amplifier component. The second end of the first injection resistor R 1in is connected to the first end of the first injection capacitor C 1in , and the second end of the first injection capacitor C 1in is grounded.

[0008] Preferably, the second CSCC includes a second sampling resistor R2, a second inverting operational amplifier component, and a second injection branch. The first end and the second end of the second sampling resistor R2 are respectively connected to the output end of the second current transformer. The second injection branch includes a second injection resistor R 2in and a second injection capacitor C 2in . The second injection resistor R 2inThe first end of is connected to the first end of the second inverting op-amp component, and the second injection resistor R 2in The second end of is connected to the first end of the second injection capacitor C 2in The first end of the second injection capacitor C 1in The second end of is grounded.

[0009] Preferably, the first inverting op-amp component includes a first inverting op-amp, a first gain resistor R 1d And a first amplification resistor R 1f , the negative pole of the first inverting op-amp is connected to the second end of the first gain resistor R 1d The first end of the first gain resistor R 1d The first end of is connected to the first end of the first sampling resistor R1, the second end of the first sampling resistor R1 is connected to the positive pole of the first inverting op-amp and grounded, and the first end of the first amplification resistor R 1f The first end of is connected to the negative pole of the first inverting op-amp, the second end of the first amplification resistor R 1f The second end of is connected to the output end of the first inverting op-amp, and the output end of the first inverting op-amp is also connected to the first end of the first injection resistor R 1in The first end of is connected.

[0010] Preferably, the second inverting op-amp component includes a second inverting op-amp, a second gain resistor R 2d And a second amplification resistor R 2f , the negative pole of the second inverting op-amp is connected to the second end of the second gain resistor R 2d The second end of the second gain resistor R 2d The second end of is connected to the first end of the second sampling resistor R2, the second end of the second sampling resistor R2 is connected to the positive pole of the second inverting op-amp and grounded, and the first end of the second amplification resistor R 2f The first end of is connected to the negative pole of the second inverting op-amp, the second end of the second amplification resistor R 2f The second end of is connected to the output end of the second inverting op-amp, and the output end of the second inverting op-amp is also connected to the first end of the second injection resistor R 2in The first end of is connected.

[0011] A control method for an active EMI filter with bidirectional electromagnetic interference suppression ability, including

[0012] Grid-side interference cancellation, specifically, the first CSCC extracts the conducted interference current, converts it into an interference voltage, and reconstructs and processes it through the first inverting op-amp component, and injects the reconstructed interference current into the ground after inputting the processed voltage into the first injection branch; the second CSCC extracts the remaining conducted interference current, converts it into an interference voltage, and reconstructs and processes it through the second inverting op-amp component, and injects the reconstructed interference current into the ground after inputting the processed voltage into the second injection branch;

[0013] The interference cancellation on the primary side of the power converter specifically means that the second CSCC extracts the conducted interference current, converts it into an interference voltage, and processes it through the second inverting operational amplifier component and reconstruction. Then, the reconstructed interference current after processing is injected into the ground after being input into the second injection branch; the first CSCC extracts the remaining conducted interference current, converts it into an interference voltage, processes it through the first inverting operational amplifier component and reconstruction, and then injects the reconstructed interference current into the ground after being input into the first injection branch.

[0014] Preferably, it includes

[0015] The current transformer extracts the conducted interference current, sends it to the sampling resistor, and converts the interference current into an interference voltage, which serves as the input voltage for the subsequent operational amplifier.

[0016] The operational amplifier processes the input interference voltage and outputs it to the injection branch.

[0017] The output reconstructed interference injects the reconstructed interference current into the ground through the injection branch, realizing the anti-phase cancellation with the original interference current.

[0018] Preferably, the current transformer extracts the conducted interference current according to a ratio of 1:n, sends it to the second sampling resistor R2, and converts the interference current into an interference voltage, which serves as the input voltage for the subsequent operational amplifier, where n is a positive integer from 1 to 10.

[0019] On the other hand, the present invention also provides a computer medium storing a program that can run the above method steps.

[0020] In the present invention, the current transformer extracts the interference current from the bus for the active EMI filter to reconstruct the interference current; the sampling resistor converts the extracted interference current into an interference voltage for the operational amplifier to achieve voltage regulation; the operational amplifier inverts the interference voltage and adjusts the amplitude for interference current injection and cancellation; the injection branch converts the interference voltage output by the operational amplifier into an interference current and injects it into the bus to achieve the suppression of the interference current. The proposed bidirectional active EMI filter adopts a dual CSCC scheme and can achieve bidirectional suppression of interference through unity gain control.

[0021] The system of the present invention can solve the suppression of conducted interference in the power converter system, improve the power density of the system, and at the same time improve the immunity of the power converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the circuit structure principle of the present invention.

[0023] Figure 2 It is Figure 1 A schematic diagram of the specific circuit structure principle (forward) when the CSCC works in

[0024] Figure 3 It isFigure 1 Schematic diagram of the specific circuit structure principle during the operation of CSCC (reverse).

[0025] Figure 4 Topology of the specific circuit structure embodiment of the present invention. Specific implementation manners

[0026] The technical solution of the present invention will be specifically described below in conjunction with the accompanying drawings and embodiments.

[0027] The basic principle of the present invention is as follows:

[0028] As Figure 2 shown, before adopting the active EMI filter, the interference current obtained by the linear impedance stabilization network is (1)

[0029] Among them, i s is the interference current of the power converter obtained by the linear impedance stabilization network, i nc is the interference current generated by the power converter (interference source), Z lisn is the impedance of the linear impedance stabilization network, Z nc is the equivalent impedance of the interference source.

[0030] After adopting the active EMI filter, the interference current obtained by the linear impedance stabilization network is

[0031] (2)

[0032] Among them, A cg is the loop gain of the first CSCC, A cs is the loop gain of the second CSCC. It can be seen that when A cs is close to 1 or A cg is relatively large, better interference suppression effects can be achieved. Figure 2 In

[0033] As Figure 3 shown, before adopting the active EMI filter, the interference current obtained by the linear impedance stabilization network is

[0034] (3)

[0035] Among them, i s is the interference current of the power converter obtained by the linear impedance stabilization network, ing is the interference current generated by the power converter (interference source), and Z lisn is the impedance of the linear impedance stabilization network, and Z ng is the equivalent impedance of the interference source.

[0036] After adopting the active EMI filter, the interference current obtained by the linear impedance stabilization network is

[0037] (4)

[0038] wherein, A cg is the loop gain of CSCC1, A cs is the loop gain of CSCC2; it can be seen that when A cg is close to 1 or A cs is relatively large, better interference suppression effect can be achieved.

[0039] In equations (2) and (4), A cs and A cg are

[0040] (5)

[0041] wherein, s is the Laplace operator, n is the turns ratio of the secondary side of the current transformer to the primary side, R1 and R2 are extraction resistors, R 1f and R 2f are the feedback resistors of the operational amplifier, R 1d and R 2d are the series resistors at the inverting terminal of the operational amplifier, R 1in and R 2in are the injection resistors, C 1in and C 2in are the injection capacitors.

[0042] In summary, in the control of the CSCC type bidirectional active EMI filter, it is necessary to ensure that A cs and A cg are both close to 1 to effectively suppress interference.

[0043] As Figure 1 shown, in the embodiment i gc is the equivalent grid-side interference current source, i ncIt is an equivalent converter interference current source. When the converter operates, serious conducted interference will be generated. According to the requirements of the EMC electromagnetic compatibility standard, this conducted interference must be suppressed to meet the requirements of the standard limit value. At the same time, interference current will also flow into the converter from the grid side, thus forming bidirectional interference. Traditional active EMI filters mainly focus on suppressing the conducted interference generated by the converter, while ignoring the bidirectional interference suppression ability of traditional passive EMI filters, which is not conducive to improving the immunity of power converters. The present invention improves the traditional active EMI filter. Based on the use of a dual CSCC face-to-face active EMI filter, bidirectional suppression of interference can be achieved through unity gain control.

[0044] As Figure 2 , Figure 3 and Figure 4 shown, the active EMI filter with bidirectional suppression ability in the embodiment includes a first suppression unit and a second suppression unit. The first end of the first suppression unit is connected to the grid side, and the second end of the first suppression unit is grounded; the first end of the second suppression unit is connected to the primary side of the power converter, and the second end of the second suppression unit is grounded, where EMI is electromagnetic interference.

[0045] The first suppression unit includes a first current transformer and a first CSCC. The first current transformer is coupled to the bus, the output of the first current transformer is connected to the first end of the first CSCC, and the second end of the first CSCC is grounded; the second suppression unit includes a second current transformer and a second CSCC. The first end of the second current transformer is connected to the grid side, the second end of the second current transformer is connected to the first end of the second CSCC, and the second end of the second CSCC is grounded, where CSCC is a current detection current compensation module.

[0046] The first CSCC includes a first sampling resistor R1, a first reverse op-amp component, and a first injection branch. The first end and the second end of the first sampling resistor R1 are respectively connected to the output end of the first current transformer. The first injection branch includes a first injection resistor R 1in and a first injection capacitor C 1in . The first end of the first injection resistor R 1in is connected to the first end of the first reverse op-amp component. The second end of the first injection resistor R 1in is connected to the first end of the first injection capacitor C 1in . The second end of the first injection capacitor C 1in is grounded.

[0047] The second CSCC includes a second sampling resistor R2, a second reverse op-amp component, and a second injection branch. The first end and the second end of the second sampling resistor R2 are respectively connected to the output end of the second current transformer. The second injection branch includes a second injection resistor R 2inand the second injection capacitor C 2in , the second injection resistor R 2in The first end of the second inverting operational amplifier component is connected to the first end of the second injection resistor R 2in The second end of the second injection capacitor C 2in The first end is connected to the second injection capacitor C 1in The second end is grounded.

[0048] The first inverting operational amplifier component includes a first inverting operational amplifier, a first gain resistor R 1d And the first amplifying resistor R 1f , the negative terminal of the first inverting op amp and the first gain resistor R 1d The second end of the first gain resistor R 1d The first end of the first sampling resistor R1 is connected to the first end of the first sampling resistor R1, the second end of the first sampling resistor R1 is connected to the positive electrode of the first reverse operational amplifier and is grounded, and the first amplifier resistor R 1f The first end of the first inverting operational amplifier is connected to the negative electrode, and the first amplifying resistor R 1f The second end of the first inverting operational amplifier is connected to the output end of the first inverting operational amplifier, and the output end of the first inverting operational amplifier is also connected to the first injection resistor R 1in The first end of the connection.

[0049] The second inverting operational amplifier component includes a second inverting operational amplifier, a second gain resistor R 2d And the second amplifying resistor R 2f , the negative terminal of the second inverting op amp and the second gain resistor R 2d The second end of the second gain resistor R 2d The second end of the second sampling resistor R2 is connected to the first end of the second sampling resistor R2, the second end of the second sampling resistor R2 is connected to the positive electrode of the second reverse operational amplifier and grounded, and the second amplifier resistor R 2f The first end is connected to the negative electrode of the second inverting operational amplifier, and the second amplifying resistor R 2f The second end of the second inverting operational amplifier is connected to the output end of the second inverting operational amplifier, and the output end of the second inverting operational amplifier is also connected to the second injection resistor R 2in The first end of the connection.

[0050] In this embodiment, the current transformer couples part of the interference current from the bus as an interference sample to provide a reference signal for the active EMI filter for reconstructing the interference signal.

[0051] The sampling resistor converts the coupled interference current into voltage, and the output interference voltage is connected to the input resistor of the operational amplifier.

[0052] The gain resistor of the inverting operational amplifier converts the interference voltage signal into an interference current signal, and the output is connected to the inverting input terminal of the operational amplifier and the feedback resistor.

[0053] The inverting operational amplifier adjusts the interference signal and outputs it in an inverted phase. Its output is connected to the injection branch. Operational amplifiers such as AD829, etc., which are high-speed broadband operational amplifiers, can be selected.

[0054] The injection branch realizes the conversion from the interference reconstruction voltage to the interference reconstruction current. Its output is connected to the reference ground to achieve interference current cancellation.

[0055] The specific steps of a control method for an active EMI filter with bidirectional electromagnetic interference suppression ability provided in the embodiment are as follows:

[0056] In the first step, the current transformer of the first CSCC extracts the conducted interference current according to 1:n and sends it to the first sampling resistor R1 to convert the interference current into an interference voltage, which serves as the input voltage of the subsequent operational amplifier. Here, n is a positive integer from 1 to 10.

[0057] In the second step, the operational amplifier processes the input interference voltage according to the gain G1(s) and outputs it to the R 1in C 1in injection branch.

[0058] In the third step, the output reconstructed interference passes through the resistor R of the injection branch 1in and the capacitor C 1in to inject the reconstructed interference current into the ground, realizing the anti-phase cancellation with the original interference current, thereby effectively suppressing the interference.

[0059] In the fourth step, the current transformer of the second CSCC extracts the conducted interference current according to 1:n and sends it to the second sampling resistor R2 to convert the interference current into an interference voltage, which serves as the input voltage of the subsequent operational amplifier.

[0060] In the fifth step, the operational amplifier processes the input interference voltage according to the gain G2(s) and outputs it to the R 2in C 2in injection branch.

[0061] In the sixth step, the output reconstructed interference passes through the resistor R of the injection branch 2in and the capacitor C 2in to inject the reconstructed interference current into the ground, realizing the anti-phase cancellation with the original interference current, thereby effectively suppressing the interference.

[0062] After the above steps, the system forms a CSCC feedforward-feedback cascaded active EMI filter, which can attenuate the bidirectional interference generated by the power converter and the power grid, that is, effectively suppress the interference generated by the power converter, and also improve the immunity of the power converter like a traditional passive EMI filter. For the interference of the power converter, CSCC1 operates in the feedback mode. The conducted interference current emitted by the power converter is extracted from the bus through a current transformer, and after passing through the negative feedback link composed of an inverting amplifier, the reconstructed interference current is injected back into the bus to achieve interference cancellation; CSCC2 operates in the feedforward mode. The conducted interference current generated by the power converter is extracted by a current transformer, and through the inverting link composed of an operational amplifier, the inverting interference current is reconstructed, and the reconstructed interference is injected into the bus through the injection branch to achieve interference cancellation. For the grid-side interference, CSCC1 operates in the feedforward mode. The conducted interference current generated on the grid side is extracted by a current transformer, and through the inverting link composed of an operational amplifier, the inverting interference current is reconstructed, and the reconstructed interference is injected into the bus through the injection branch to achieve interference cancellation. CSCC2 operates in the feedback mode. The conducted interference current emitted by the power converter is extracted from the bus through a current transformer, and after passing through the negative feedback link composed of an inverting amplifier, the reconstructed interference current is injected back into the bus to achieve interference cancellation. Since the feedback-type CSCC usually requires high gain and the feedforward-type CSCC hopes for unity gain, in order to stably implement the CSCC-type bidirectional EMI active suppression, the two active EMI filters CSCC1 and CSCC2 must be controlled in the unity gain mode.

[0063] The specific embodiments described in this article are only illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An active EMI filter with bidirectional electromagnetic interference suppression capability, characterized in that: It includes a first suppression unit and a second suppression unit, wherein the first end of the first suppression unit is connected to the grid side, and the second end of the first suppression unit is grounded; the first end of the second suppression unit is connected to the primary side of the power converter, and the second end of the second suppression unit is grounded, wherein EMI is electromagnetic interference; The first suppression unit includes a first current transformer and a first CSCC, the first current transformer is coupled to a bus, the output of the first current transformer is connected to a first end of the first CSCC, and the second end of the first CSCC is grounded; the second suppression unit includes a second current transformer and a second CSCC, the first end of the second current transformer is connected to a grid side, the second end of the second current transformer is connected to a first end of the second CSCC, and the second end of the second CSCC is grounded, wherein the CSCC is a current detection current compensation module; The first CSCC and the second CSCC are connected in a mirrored manner.

2. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 1, characterized in that: The first CSCC includes a first sampling resistor R1, a first inverting operational amplifier component and a first injection branch. The first end and the second end of the first sampling resistor R1 are respectively connected to the output end of the first current transformer. The first injection branch includes a first injection resistor R1 connected in sequence. 1in and the first injection capacitor C 1in , the first injection resistor R 1in The first end of the first inverting operational amplifier component is connected to the first end of the first injection resistor R 1in The second end of the first injection capacitor C 1in The first end of the first injection capacitor C 1in The second end is grounded.

3. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 1, characterized in that: The second CSCC includes a second sampling resistor R2, a second inverting operational amplifier component and a second injection branch. The first end and the second end of the second sampling resistor R2 are respectively connected to the output end of the second current transformer. The second injection branch includes a second injection resistor R2 connected in sequence. 2in and the second injection capacitor C 2in , the second injection resistor R 2in The first end of the second inverting operational amplifier component is connected to the first end of the second injection resistor R 2in The second end of the second injection capacitor C 2in The first end of the second injection capacitor C 1in The second end is grounded.

4. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 2, characterized in that: The first inverting operational amplifier component includes a first inverting operational amplifier, a first gain resistor R 1d And the first amplifying resistor R 1f , the negative electrode of the first inverting op amp and the first gain resistor R 1d The second end of the first gain resistor R 1d The first end of the first sampling resistor R1 is connected to the first end of the first sampling resistor R1, the second end of the first sampling resistor R1 is connected to the positive electrode of the first reverse operational amplifier and is grounded, and the first amplifier resistor R 1f The first end of the first amplifier resistor R 1f The second end of the first inverting operational amplifier is connected to the output end of the first inverting operational amplifier, and the output end of the first inverting operational amplifier is also connected to the first injection resistor R 1in The first end of the connection.

5. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 3, characterized in that: The second inverting operational amplifier component includes a second inverting operational amplifier, a second gain resistor R 2d And the second amplifying resistor R 2f , the negative electrode of the second inverting op amp and the second gain resistor R 2d The second end of the second gain resistor R 2d The second end of the second sampling resistor R2 is connected to the first end of the second sampling resistor R2, the second end of the second sampling resistor R2 is connected to the positive electrode of the second reverse operational amplifier and is grounded, and the second amplifier resistor R 2f The first end is connected to the negative electrode of the second inverting operational amplifier, and the second amplifying resistor R 2f The second end of the second inverting operational amplifier is connected to the output end of the second inverting operational amplifier, and the output end of the second inverting operational amplifier is also connected to the second injection resistor R 2in The first end of the connection.

6. A control method for an active EMI filter with bidirectional electromagnetic interference suppression capability as claimed in claim 1, characterized in that: include The interference cancellation on the grid side is specifically that the first CSCC extracts the conducted interference current and converts it into interference voltage and reconstructs it through the first inverting operational amplifier component, and then the reconstructed interference current after the processed voltage is input into the first injection branch is injected into the ground; The second CSCC extracts the remaining conducted interference current and converts it into interference voltage, reconstructs it through the second inverting operational amplifier component, and inputs the processed voltage into the reconstructed interference current after the second injection branch and injects it into the ground; The interference on the primary side of the power converter is cancelled, specifically, the second CSCC extracts the conducted interference current, converts it into an interference voltage, reconstructs it through the second reverse operational amplifier component, and inputs the processed voltage into the second injection branch, and then injects the reconstructed interference current into the ground; the first CSCC extracts the remaining conducted interference current, converts it into an interference voltage, reconstructs it through the first reverse operational amplifier component, and then inputs it into the first injection branch, and then injects the reconstructed interference current into the ground.

7. The control method of the active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 6, characterized in that: include The current transformer extracts the conducted interference current and sends it to the sampling resistor, which converts the interference current into interference voltage as the input voltage of the subsequent operational amplifier; The operational amplifier processes the input interference voltage and outputs it to the injection branch; The output reconstructed interference injects the reconstructed interference current into the ground through the injection branch to achieve anti-phase cancellation with the original interference current.

8. The control method of the active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 6, characterized in that: The current transformer extracts the conducted interference current according to 1:n and sends it to the second sampling resistor R2 to convert the interference current into an interference voltage as the input voltage of the subsequent operational amplifier, where n is a positive integer of 1-10.

9. A computer medium, characterized in that A program is stored, and the program can run the control method of the active EMI filter with bidirectional electromagnetic interference suppression capability as described in claims 6-8.

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