Active EMI filter with bidirectional electromagnetic interference suppression capability

Abstract

The invention relates to an active EMI filter with bidirectional electromagnetic interference suppression capability, which comprises a first suppression unit and a second suppression unit, and is characterized in that the first end of the first suppression unit is connected to a power 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. According to the invention, a current transformer extracts interference current from a bus and is used for an active EMI filter to reconstruct the interference current; the sampling resistor converts the extracted interference current into interference voltage for the operational amplifier to realize voltage regulation; the operational amplifier inverts the phase of the interference voltage, adjusts the amplitude of the interference voltage and then injects and counteracts the interference current; the injection branch converts interference voltage output by the operational amplifier into interference current and injects the interference current into a bus, and suppression of the interference current is achieved. The bidirectional active EMI filter adopts a double-CSCC scheme, and bidirectional suppression of interference can be realized through unity gain control.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic compatibility of power electronic devices, and in particular 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, and defense, and are one of the key basic technology devices for scientific and technological progress and development. When a power converter is working in a switching state, it will generate very high du / dt and di / dt (voltage and current change rate) while converting electric energy, and will generate conducted and radiated interference, affecting the normal operation of surrounding equipment. The traditional way to suppress conducted interference is to use passive EMI filters. As power converters develop towards high frequency and high power density, passive EMI filters can account for 30% to 50% of the entire power converter due to their large size and weight, which is one of the main factors affecting the integrated development of power converters. The use of active EMI filters can significantly reduce the size and weight of EMI filters, and is one of the key technologies for the development of high power density power converters. Current research on active EMI filters mainly focuses on the suppression of unidirectional EMI with power converters as interference sources, while traditional passive EMI filters usually have bidirectional interference suppression capabilities. In addition to suppressing the conducted interference of power converters, they can also suppress the conducted interference and radiated coupling interference on the grid side to improve the anti-interference of power converters. Therefore, research on active EMI filters needs to further improve their EMI suppression function. Summary of the invention

[0003] During the operation of the power converter, serious electromagnetic interference will be generated due to the high-frequency operation of the power switch, which may easily cause the surrounding electrical and electronic equipment to malfunction. The traditional method of suppressing interference is to use a passive EMI filter, but its power density is very low, and it occupies a large space and weight in the power converter. Under the development trend of high frequency and high power density of power converters, the problem of high volume and weight of passive EMI filters needs to be solved urgently. Active EMI filters use components with higher power density to form active interference cancellation circuits, which can significantly improve the power density of power converters. Traditional active EMI filters mainly focus on the interference suppression problem on the power converter side, while passive EMI filters actually have bidirectional interference suppression capabilities, which can improve the anti-interference of power converters. Therefore, the present invention proposes an active EMI filter with bidirectional interference suppression capability, which adopts a dual CSCC face-to-face structure and unit gain control to achieve bidirectional interference suppression. While suppressing the conducted interference of the power converter, its anti-interference degree is improved.

[0004] The present invention mainly aims at the problem that the passive suppression power density of conducted interference of power converter is low and the current active suppression usually only has unidirectional EMI suppression capability, and proposes an active EMI filter topology and control method with bidirectional EMI suppression capability. The topology adopts CSCC feedforward and feedback cascade hybrid active circuit, and the control method ensures that from the perspective of both the converter and the grid side, they belong to consistent feedforward and feedback cascade active EMI filters, thereby 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 capability comprises 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.

[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, wherein the CSCC 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, wherein 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, and 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.

[0008] Preferably, the second CSCC includes a second sampling resistor R2, a second inverting operational amplifier component and a second injection branch, wherein 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, and 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 2inThe 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.

[0009] Preferably, 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.

[0010] Preferably, 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 positive 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.

[0011] A control method for an active EMI filter with bidirectional electromagnetic interference suppression capability, comprising: 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 reverse operational amplifier component, and then inputs the processed voltage into the first injection branch and then the reconstructed interference current is injected into the ground; the second CSCC extracts the remaining conducted interference current and converts it into interference voltage and reconstructs it through the second reverse operational amplifier component, and then inputs the processed voltage into the second injection branch and then the reconstructed interference current is injected 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.

[0012] Preferably, including 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.

[0013] Preferably, the current transformer extracts the conducted interference current according to 1:n, sends it to the second sampling resistor R2, converts the interference current into an interference voltage, and serves as the input voltage of the subsequent operational amplifier, wherein n is a positive integer of 1-10.

[0014] On the other hand, the present invention also provides a computer medium storing a program, wherein the program can execute the above method steps.

[0015] In the present invention, the current transformer extracts interference current from the busbar, which is used for active EMI filter to reconstruct interference current; the sampling resistor converts the extracted interference current into interference voltage, which is used for voltage regulation by the operational amplifier; the operational amplifier inverts the interference voltage and adjusts the amplitude for interference current injection and offset; the injection branch converts the interference voltage output by the operational amplifier into interference current and injects it into the busbar to suppress interference current. The proposed bidirectional active EMI filter adopts a dual CSCC scheme, which can achieve bidirectional suppression of interference through unit gain control.

[0016] The system of the present invention can solve the problem of conducting interference suppression of a power converter system, improve the power density of the system, and simultaneously improve the anti-interference performance of the power converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the circuit structure principle of the present invention.

[0018] Figure 2 for Figure 1 Schematic diagram of the specific circuit structure principle when CSCC is working (forward).

[0019] Figure 3 for Figure 1 Schematic diagram of the specific circuit structure principle when CSCC is working (reverse).

[0020] Figure 4 This is a specific circuit structure embodiment topology of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0022] The basic principles of the present invention are as follows: like Figure 2 As shown in the figure, the interference current obtained by the linear impedance stabilization network before the active EMI filter is used (1) in, i s The interference current of the power converter obtained for 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.

[0023] After using the active EMI filter, the interference current obtained by the linear impedance stabilization network is (2) in, A cg is the loop gain of the first CSCC, A cs It can be seen that the loop gain of the second CSCC is A cs Near 1 o'clock or A cg When it is larger, the interference suppression can be more effective. Figure 2 In the figure, the first CSCC is marked as CSCC1 and the second CSCC is marked as CSCC2.

[0024] like Figure 3 As shown in Figure 2, before using the active EMI filter, the interference current obtained by the linear impedance stabilization network is: (3) in, i s The interference current of the power converter obtained for the linear impedance stabilization network, i ng is the interference current generated by the power converter (interference source), Z lisn is the impedance of the linear impedance stabilization network, Z ng is the equivalent impedance of the interference source.

[0025] After using the active EMI filter, the interference current obtained by the linear impedance stabilization network is (4) in, A cg is the loop gain of CSCC1, A cs is the loop gain of CSCC2; it can be seen that when A cg Near 1 o'clock or A cs When it is larger, the interference suppression can be more effective.

[0026] In formula (2) and formula (4), A cs and A cg for (5)

[0027] Where s is the Laplace operator, n is the ratio of the secondary side to the primary side of the current transformer, R1 and R2 are extraction resistors, R 1f and R 2f is the feedback resistor of the op amp, R 1d and R 2d is the series resistance of the op amp’s reverse terminal, R 1in and R 2in is the injection resistance, C 1in and C 2in is the injection capacitor.

[0028] In summary, in the control of CSCC type bidirectional active EMI filter, it is necessary to ensure A cs and A cg All of them need to be close to 1 to ensure effective interference suppression.

[0029] like Figure 1 As 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 is working, serious conducted interference will be generated. According to the EMC electromagnetic compatibility standard requirements, the conducted interference must be suppressed to meet the standard limit requirements. At the same time, interference current will flow into the converter from the grid side, thereby forming bidirectional interference. Traditional active EMI filters mainly focus on the suppression of conducted interference produced by the converter, but ignore the bidirectional interference suppression capability of traditional passive EMI filters, which is not conducive to improving the anti-interference ability of power converters. The present invention improves the traditional active EMI filter. On the basis of adopting a dual CSCC face-to-face active EMI filter, bidirectional suppression of interference can be achieved through unit gain control.

[0030] like Figure 2 , Figure 3 and Figure 4 As shown, the active EMI filter with bidirectional suppression capability in the embodiment 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.

[0031] 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, wherein the CSCC current detection current compensation module.

[0032] 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.

[0033] 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. 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.

[0034] 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 positive electrode of 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.

[0035] 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 positive 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The inverting amplifier adjusts the interference signal and outputs it in an inverted manner, and its output is connected to the injection branch. The operational amplifier can be a high-speed broadband operational amplifier such as AD829.

[0040] The injection branch realizes the conversion of the interference reconstruction voltage to the interference reconstruction current, and the output is connected to the reference ground to realize the interference current cancellation.

[0041] The specific steps of a control method of an active EMI filter with bidirectional electromagnetic interference suppression capability provided in the embodiment are as follows: In the first step, the current transformer of the first CSCC extracts the conducted interference current according to 1:n, sends it to the first sampling resistor R1, converts the interference current into an interference voltage, and serves as the input voltage of the subsequent operational amplifier, where n is a positive integer of 1-10.

[0042] In the second step, the op amp processes the input interference voltage according to the gain G1(s) and outputs it to R 1in C 1in Injection branch.

[0043] The third step is to output the reconstruction interference through the resistor R of the injection branch. 1in and capacitor C 1in The reconstructed interference current is injected into the ground to achieve anti-phase cancellation with the original interference current, thereby achieving effective interference suppression.

[0044] 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, converting the interference current into an interference voltage as the input voltage of the subsequent operational amplifier.

[0045] Step 5: The op amp processes the input interference voltage according to the gain G2(s) and outputs it to R 2in C 2in Injection branch.

[0046] Step 6: Output reconstruction interference through the resistor R of the injection branch 2in and capacitor C 2in The reconstructed interference current is injected into the ground to achieve anti-phase cancellation with the original interference current, thereby achieving effective interference suppression.

[0047] After the above steps, the system constitutes a CSCC feedforward-feedback cascade 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 can also improve the anti-interference of the power converter like a traditional passive EMI filter. For the interference of the power converter, CSCC1 works in feedback mode, extracts the conducted interference current emitted by the power converter from the bus through the current transformer, and injects the reconstructed interference current back to the bus through the negative feedback link composed of the inverting amplifier to achieve interference cancellation; CSCC2 works in feedforward mode, extracts the conducted interference current generated by the power converter by the current transformer, reconstructs the inverting interference current through the inverting link composed of the operational amplifier, and injects the reconstructed interference into the bus through the injection branch to achieve interference cancellation. For the grid-side interference, CSCC1 works in feedforward mode, extracts the conducted interference current generated by the grid side by the current transformer, reconstructs the inverting interference current through the inverting link composed of the operational amplifier, and injects the reconstructed interference into the bus through the injection branch to achieve interference cancellation. CSCC2 works in feedback mode, extracting the conducted interference current emitted by the power converter from the bus through the current transformer, and injecting the reconstructed interference current back to the bus through the negative feedback link composed of the inverting amplifier 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 realize the CSCC type bidirectional EMI active suppression, the two active EMI filters CSCC1 and CSCC2 must be controlled in unity gain mode.

[0048] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them with similar methods, 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.

2. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 1, characterized in that: 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, wherein the CSCC is a current detection current compensation module.

3. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 2, 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.

4. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 2, 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.

5. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 3, 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.

6. The active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 4, 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 positive 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.

7. A control method for an active EMI filter with bidirectional electromagnetic interference suppression capability, 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.

8. The control method of the active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 7, 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.

9. The control method of the active EMI filter with bidirectional electromagnetic interference suppression capability according to claim 7, 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.

10. 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 7-9.

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