Feedforward voltage sampling double-compensated active electromagnetic interference filter based on impedance mismatch and design method thereof

Abstract

The application discloses a feedforward voltage sampling double-compensation active electromagnetic interference filter based on impedance mismatch and a design method thereof, and belongs to the field of power electronics, which comprises the following steps: constructing an equivalent circuit according to an impedance mismatch principle, determining a circuit topology of the filter according to the equivalent circuit, determining resistance and capacitance values according to a cutoff frequency and impedance of an RC circuit, determining an amplification multiple according to a unit gain bandwidth of an operational amplifier, determining a turns ratio of a transformer according to the impedance mismatch principle and the amplification multiple, determining a resistance value of a voltage injection module according to a damping effect, and determining a capacitance value of a current injection module according to a leakage constraint. The method disclosed by the application can widen an interference suppression frequency band, improve an insertion loss, realize impedance matching, and greatly reduce the volume of the filter due to the parameter design characteristics of the feedforward filter, thereby adapting to the demand of a new generation of power electronic equipment for small volume and high suppression effect.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to an impedance mismatch-based feedforward voltage sampling double-compensation active electromagnetic interference filter and a design method thereof. Background Art

[0002] Today's power electronic devices have significantly improved in size and efficiency compared to previous generations. However, higher switching speeds and frequencies can worsen the electromagnetic environment surrounding the devices, significantly increasing the frequency and amplitude of interference noise and exacerbating electromagnetic interference (EMI) issues. While traditional passive EMI filters can effectively suppress noise, they rely on bulky magnetic components (such as common-mode inductors), making them difficult to meet the miniaturization requirements of modern devices. Traditional active EMI filters offer superior filtering effectiveness at low frequencies compared to passive EMI filters. However, their single compensation method cannot simultaneously address impedance mismatches on both the noise source side and the Line Impedance Stabilization Network (LISN) side, limiting their noise suppression effectiveness. Hybrid EMI filters utilize both passive and active filter components, achieving a new balance between noise suppression and size optimization. Although smaller than traditional passive EMI filters, hybrid active filters are still bulky compared to active filters. Summary of the Invention

[0003] The purpose of this application is to overcome the defects of the prior art and provide a feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch and its design method, which can not only reduce the volume but also meet the impedance mismatch and effectively suppress noise interference.

[0004] In a first aspect, the present application provides a design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, comprising the following steps:

[0005] An equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is constructed according to an impedance mismatch principle, and a circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is determined according to the equivalent circuit, wherein the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module;

[0006] The structure of the voltage sampling module is determined according to the RC high-pass property, and the resistance value and capacitance of the voltage sampling module are determined according to the cutoff frequency and impedance of the RC high-pass circuit;

[0007] Determine the operational amplifier model of the signal amplification module and the effective bandwidth required by the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter, and determine the amplification factor of the signal amplification module based on the unit gain bandwidth and effective bandwidth of the operational amplifier model;

[0008] Determine the turns ratio of the transformer in the voltage injection module according to the impedance mismatch principle and the amplification factor of the signal amplification module;

[0009] Determine the compensation resistance value of the voltage injection module according to the damping effect;

[0010] The compensation capacitance value of the current injection module is determined according to the leakage constraint, and the design of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is completed.

[0011] Optionally, an equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is constructed according to the impedance mismatch principle, and a circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is determined according to the equivalent circuit. The feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module, including:

[0012] According to the impedance mismatch principle, an equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is constructed, and the equivalent impedance of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is determined;

[0013] According to the impedance mismatch principle and the equivalent impedance of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, the positions and equivalent impedance values ​​of voltage compensation and current compensation are determined respectively;

[0014] The equivalent circuit of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter is decomposed into functional modules to obtain the circuit topology of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter. The impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module.

[0015] Optionally, according to the impedance mismatch principle and the equivalent circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, the positions and equivalent impedance values ​​of the voltage compensation and current compensation are determined, including: according to the impedance mismatch principle, setting the voltage compensation in series in the noise loop, the voltage compensation is close to the interfered end, and forms an impedance mismatch with the load equivalent impedance of the interfered end; setting the current compensation in parallel in the noise loop is close to the noise source end, and forms an impedance mismatch with the noise source end;

[0016] The equivalent impedance of voltage compensation is , the expression is:

[0017]

[0018] in, is the voltage compensation coefficient, is the load impedance at the interfered end, G is the magnification, H represents the sampling coefficient;

[0019] The equivalent impedance of current compensation is , the expression is:

[0020]

[0021] in, is the current compensation coefficient, G is the magnification, H Indicates the sampling factor.

[0022] Optionally, since the impedance value of the interfered end is small, a high impedance should be connected in series to meet the impedance mismatch requirement, and k v GH=1, the equivalent impedance Z of voltage compensation v is a high impedance, which satisfies the impedance mismatch and obtains the voltage compensation coefficient k v =1 / GH, which is the transformer turns ratio.

[0023] Optionally, the number of turns of the secondary side of the transformer in the voltage injection module is set to be smaller than the number of turns of the primary side; the diameter of the secondary side wire of the transformer in the voltage injection module is set to be larger than the diameter of the primary side wire to meet the voltage compensation coefficient k v At the same time, the filter size is reduced.

[0024] Optionally, the operational amplifier model of the signal amplification module and the effective bandwidth required by the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter are determined, and the amplification factor of the signal amplification module is determined according to the unit gain bandwidth and effective bandwidth of the operational amplifier model, including selecting the operational amplifier according to the effective bandwidth requirement, determining the unit bandwidth gain product of the operational amplifier according to the operational amplifier model, determining the amplification factor that meets the effective bandwidth requirement according to the unit bandwidth gain product of the operational amplifier, and determining the resistance values ​​of the input resistor and the feedback resistor according to the amplification factor.

[0025] Optionally, the compensation capacitance value of the current injection module is determined according to the leakage constraint to complete the design of the electromagnetic interference filter, including setting the current injection module as the compensation capacitance according to the equivalent impedance of the current compensation; and setting the AC peak voltage according to the safety standard. , leakage current and mains frequency , based on the leakage formula Get the maximum capacitance of the compensation capacitor; determine the capacitance of the compensation capacitor in the current injection module based on the maximum capacitance of the compensation capacitor .

[0026] In the second aspect, the present application also provides a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, which applies the design method of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch as described in the first aspect. The feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is connected between the interfered end and the noise source end, including: a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module. The first end and the second end of the voltage sampling module are connected in parallel between the noise source ends, the third end of the voltage sampling module is connected to the first end of the signal amplification module, the second end of the signal amplification module is connected to the first end of the current injection module, the second end of the current injection module is connected to the first end of the voltage injection module, the third end of the current injection module is connected to the second end of the interfered end, the second end of the voltage injection module is connected to the second end of the signal amplification module, and the third end of the voltage injection module is connected to the first end of the interfered end.

[0027] Optionally, the voltage injection module is close to the interfered end, the equivalent impedance of the voltage injection module is large, and an impedance mismatch is formed with the interfered end; the current injection module is close to the noise source end, the equivalent impedance of the current injection module is small, and an impedance mismatch is formed with the noise source end.

[0028] Optionally, the voltage sampling module, the signal amplification module, the current injection module, and the voltage injection module constitute a feedforward voltage sampling dual compensation structure.

[0029] The present application provides a feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch and a design method thereof. By constructing an equivalent circuit based on the impedance mismatch principle, the equivalent impedance of the electromagnetic interference filter and voltage and current compensation can be accurately determined; the circuit is decomposed into voltage sampling, signal amplification, current injection and voltage injection modules, which can suppress electromagnetic interference in a targeted manner; by setting a feedforward voltage sampling dual compensation structure to form an impedance mismatch structure with the interference source end and the interfered end respectively, high insertion loss can be achieved; the amplification factor is determined in combination with the unit gain bandwidth of the operational amplifier, and the resistance and current of the voltage injection module are designed according to the damping effect and leakage constraints. Parameters such as the injection module capacitance can effectively suppress electromagnetic interference in the entire frequency band and significantly improve the noise suppression effect; the design of fewer turns and thicker wire diameter on the secondary side and more turns and thinner wire diameter on the primary side can effectively reduce the volume of the filter, effectively widen the interference suppression frequency band, improve insertion loss, and achieve impedance matching. Due to the special structure of the feedforward filter, the voltage injection module can have fewer turns on the main power side and more turns on the filter side. Since the wire diameter on the main power side is thick and the wire diameter on the filter side is very thin, the volume of the filter is greatly reduced, providing more reliable electromagnetic compatibility protection for electronic equipment, and can meet the needs of the new generation of power electronic equipment for small size and high suppression effect.

[0030] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a flow chart of a design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch provided in one embodiment of the present application.

[0033] Figure 2 This is a flowchart of step S1 in a design method of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch provided in one embodiment of the present application.

[0034] Figure 3 This is a schematic diagram of equivalent impedance in a design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch provided in one embodiment of the present application.

[0035] Figure 4This is a gain diagram of an operational amplifier in a design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch provided in one embodiment of the present application.

[0036] Figure 5 This is a comparison diagram of the design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter provided in one embodiment of the present application and the original noise simulation spectrum.

[0037] Figure 6 This is a comparison diagram of the design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter and the simulated spectrum of the feedforward voltage sampling current compensation active common-mode electromagnetic interference filter provided in one embodiment of the present application.

[0038] Figure 7 This is a comparison diagram of the design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter and the simulated spectrum of the feedforward voltage sampling voltage compensation active common-mode electromagnetic interference filter provided in one embodiment of the present application.

[0039] Figure 8 This is a schematic structural diagram of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch provided in one embodiment of the present application.

[0040] Figure 9 This is a specific circuit topology diagram of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch provided in one embodiment of the present application.

[0041] In the figure: 1. Feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, 2. Interference end, 3. Noise source end, 11. Voltage sampling module, 12. Signal amplification module, 13. Current injection module, 14. Voltage injection module. DETAILED DESCRIPTION

[0042] To make the purpose and technical solutions of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In one embodiment, see Figure 1 The present application provides a design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch. The design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch may include the following steps: step S1 to step S6.

[0044] Step S1: constructing an equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch according to the impedance mismatch principle, and determining the circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch according to the equivalent circuit, wherein the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module.

[0045] Step S2: determining the structure of the voltage sampling module according to the RC high-pass property, and determining the resistance value and capacitance of the voltage sampling module according to the cutoff frequency and impedance of the RC high-pass circuit.

[0046] Step S3: Determine the operational amplifier model of the signal amplification module and the effective bandwidth required by the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter, and determine the amplification factor of the signal amplification module according to the unit gain bandwidth and effective bandwidth of the operational amplifier model.

[0047] Step S4: determining the turns ratio of the transformer in the voltage injection module according to the impedance mismatch principle and the amplification factor of the signal amplification module.

[0048] Step S5: determining the compensation resistance value of the voltage injection module according to the damping effect.

[0049] Step S6: Determine the compensation capacitance value of the current injection module according to the leakage constraint, and complete the design of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter.

[0050] In the electromagnetic interference filter design method of the present application, by constructing an equivalent circuit based on the impedance mismatch principle, the impedance mismatch between the filter and the interference source and load is maximized from a theoretical perspective, thereby improving the interference attenuation efficiency from the source; the RC high-pass characteristic is used to accurately match the cutoff frequency and impedance, so that the voltage sampling module can accurately capture the broadband interference signal; the amplification factor is determined in combination with the unit gain bandwidth of the operational amplifier to avoid signal distortion while ensuring amplification accuracy; the transformer turns ratio is designed in collaboration with the impedance mismatch principle and the amplification factor to achieve efficient signal transmission and impedance matching optimization; the current injection module capacitance value and the voltage injection module resistance value are determined according to the leakage constraint and the damping effect, respectively, which can enhance the filtering stability while suppressing the leakage risk. The method of the present application can effectively broaden the interference suppression frequency band, improve the insertion loss, and achieve impedance matching. At the same time, due to the special structure of the feedforward filter, the voltage compensation main power side has fewer turns and the filter side has more turns. Since the main power side wire diameter is thick and the filter side wire diameter is very thin, the volume of the filter is greatly reduced, providing more reliable electromagnetic compatibility protection for electronic equipment.

[0051] In step S1, please refer to Figure 1 In step S1, please refer to

[0052] As an example, please refer to Figure 2 Step S1 can include the following steps: step S11~step S13.

[0053] Step S11: according to the impedance mismatch principle, the equivalent circuit of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter is constructed, and the equivalent impedance of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter is determined.

[0054] Step S12: according to the impedance mismatch principle and the equivalent impedance of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter, the positions and equivalent impedance values of voltage compensation and current compensation are determined respectively.

[0055] Step S13: the equivalent circuit of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter is decomposed into functional modules to obtain the circuit topology of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter, and the electromagnetic interference filter includes a voltage sampling module, a signal amplification module, a current injection module and a voltage injection module.

[0056] As an example, in step S11, since the passive filter is usually designed with impedance mismatch principle to determine the structure of the filter, the filter type is designed flexibly according to different noise source end and interference end, so that the insertion loss of the filter can be effectively improved. Since the impedance value in series in the noise loop is high impedance, and the impedance in parallel in the noise loop is low impedance, but the equivalent impedance of the traditional active filter has only one equivalent impedance, which cannot form impedance mismatch with the interference end and the noise source end at the same time. According to the impedance mismatch principle of the passive filter and the single equivalent impedance principle of the active filter, the equivalent circuit of the electromagnetic interference filter is constructed, as shown in Figure 3 The load impedance of the interference end is Z L The source impedance of the noise source end is Z s The equivalent noise source voltage is v ENSThe equivalent circuit of the feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch includes two equivalent impedances, one equivalent impedance connected in series in the noise loop and an equivalent impedance in parallel in the noise loop , where the equivalent impedance in series with the noise loop is High impedance, equivalent impedance in parallel with the noise loop For low impedance.

[0057] As an example, in step S12, see Figure 3 According to the impedance mismatch principle, the equivalent impedance in series with the noise circuit should be set Close to the interfered end, there is an impedance mismatch with the equivalent impedance of the load at the interfered end; set the equivalent impedance in parallel in the noise loop Close to the noise source, there is impedance mismatch with the noise source.

[0058] As an example, the equivalent impedance in series in the noise loop can be set as voltage compensation. If the voltage compensation is close to the interfered end, the equivalent impedance of the voltage compensation is , the expression is:

[0059]

[0060] in, is the voltage compensation coefficient, is the load impedance at the interfered end, G is the magnification, H Indicates the sampling coefficient. When the voltage compensation equivalent impedance will be infinite, meeting the high impedance requirement of impedance mismatch, and forming an impedance mismatch with the interfered end.

[0061] As an example, the equivalent impedance in parallel with the noise loop can be set The current compensation is close to the noise source end, and there is an impedance mismatch with the noise source end. The equivalent impedance of the current compensation is , the expression is:

[0062]

[0063] in, is the current compensation coefficient, G is the magnification, H Indicates the sampling factor.

[0064] As an example, in step S13, the equivalent impedance according to voltage compensation is The equivalent impedance of current compensation is The equivalent circuit of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter is decomposed into functional modules to obtain a circuit of the impedance mismatch based feedforward voltage sampling double compensation active electromagnetic interference filter, which comprises a voltage sampling module, a signal amplification module, a current injection module and a voltage injection module, the input end of the voltage sampling module is connected to a noise source end, the output end of the voltage sampling module is connected to the input end of the signal amplification module, the input end of the current injection module is connected to the output end of the signal amplification module, the output end of the current injection module is connected to the voltage injection module in series, and the output end of the voltage injection module is connected to a disturbed end.

[0065] As an example, the voltage sampling module is arranged close to the noise source end, the voltage injection module and the current injection module are arranged close to the disturbed end to form a feedforward circuit, and the voltage injection module is arranged after the current injection module and closer to the disturbed end.

[0066] As an example, the voltage sampling module collects the interference voltage of the noise source end, the signal amplification module amplifies the weak interference signal output by the voltage sampling module to provide a signal with sufficient intensity for compensation control, the current injection module receives the output signal of the signal amplification module according to the equivalent impedance design of current compensation, generates and injects a compensation current opposite to the interference current, avoids the compensation current from being absorbed by the interference source through the mismatch characteristics of the system loop impedance, and efficiently cancels the interference current, and the voltage injection module receives the amplified signal based on the equivalent impedance parameters of voltage compensation, generates and injects a compensation voltage opposite to the interference voltage, and ensures that the compensation voltage effectively acts on the disturbed end to cancel the interference voltage by using the mismatch relationship with the system impedance.

[0067] As an example, the voltage injection module and the current injection module share one signal amplification module and one voltage sampling module, and realize filtering through respective compensation circuits.

[0068] In step S2, please refer to step S2 in Figure 1 , the structure of the voltage sampling module is determined according to the RC high-pass property, and the resistance value of the voltage sampling module and the capacitance value of the voltage sampling module are determined according to the cutoff frequency and impedance of the RC high-pass circuit.

[0069] As an example, a first-order RC high-pass circuit can be used as the voltage sampling module according to the RC high-pass property, the voltage sampling module comprises a resistance and a capacitor connected thereto, and the detection of the electromagnetic interference filter in the conducted electromagnetic interference range is realized.

[0070] Furthermore, the fundamental frequency of the noise spectrum is determined according to the switching frequency in the noise source circuit, and the cutoff frequency of the voltage sampling module is set according to the fundamental frequency, so that the cutoff frequency of the voltage sampling module is lower than the fundamental frequency of the noise spectrum, so as to effectively collect noise signals and suppress high-frequency interference.

[0071] As an example, the cutoff frequency of the voltage sampling module may take a 5-fold margin, that is, the cutoff frequency of the voltage sampling module may be set to one-fifth of the fundamental frequency.

[0072] Furthermore, if the impedance of the RC circuit is low, a low-impedance path will be formed from the noise source to ground, reducing the load impedance of the active electromagnetic interference filter and affecting its operation. Therefore, according to the RC circuit impedance formula, the resistance and capacitance values ​​are set to meet the cutoff frequency and impedance.

[0073] As an example, the resistance value of the voltage sampling module is preferably a high resistance value.

[0074] In one example, if the switching frequency of the noise source is 100kHz, the fundamental frequency of the noise spectrum is also 100kHz. Therefore, the cutoff frequency of the voltage sampling module should be lower than 100kHz. With a margin of 5 times, the cutoff frequency of the voltage sampling module can be set to 20kHz. Based on the RC circuit impedance formula, a high resistance value is preferred. To meet the cutoff frequency and impedance requirements, the voltage sampling module has a resistance of 100Ω and a capacitance of 80nF, resulting in a cutoff frequency of 19.89kHz.

[0075] In step S3, see Figure 1 In step S3, the operational amplifier model of the signal amplification module and the effective bandwidth required by the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter are determined, and the amplification factor of the signal amplification module is determined according to the unit gain bandwidth and the effective bandwidth of the operational amplifier model.

[0076] As an example, an operational amplifier with high unity gain bandwidth is selected based on the effective bandwidth required by a feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch, and the unity bandwidth gain product of the operational amplifier is determined based on the model of the operational amplifier. , according to the unity bandwidth gain product of the operational amplifier Determine the amplification factor G that meets the effective bandwidth requirements, and determine the input resistance based on the amplification factor G and feedback resistor The resistance value of the input resistor is much larger than the signal source impedance.

[0077] Specifically, according to the unity bandwidth gain product of the operational amplifier , we can get the effective bandwidth of the operational amplifier With magnification The relationship is expressed as:

[0078]

[0079] Among them, the magnification The expression is:

[0080]

[0081] in, is the feedback resistor, is the input resistance.

[0082] Furthermore, since the conducted electromagnetic interference is , the effective bandwidth of the operational amplifier should be Greater than the conducted electromagnetic interference range, the unit bandwidth gain product of the operational amplifier is , effective bandwidth Substituting into the above formula we can get the amplification factor G of the operational amplifier.

[0083] Furthermore, in order to reduce the load effect of the signal source, it is necessary to ensure that the signal amplification module can accurately obtain and process the signal at the noise source end. If the input resistance is too small, the output current of the noise source will increase. According to Ohm's law, the voltage drop on the internal resistance of the noise source will increase significantly, causing the actual voltage entering the signal amplification module to be attenuated, thereby affecting the sampling accuracy and amplification effect. When the impedance is much greater than the noise source end, the load on the noise source end is lighter, the signal attenuation during transmission is minimal, and the noise signal can be more accurately transmitted to the signal amplification loop module, ensuring that the signal amplification module works according to the designed amplification factor, thereby ensuring that the filter's noise detection and compensation effects meet expectations. Therefore, the input resistance can be set Much larger than the noise source impedance.

[0084] Furthermore, according to the input resistance And the amplification factor G can be obtained by the feedback resistance .

[0085] As an example, the input resistance With feedback resistor Calculating effective bandwidth to verify whether the target frequency band of conducted electromagnetic interference is covered and to avoid gain attenuation affecting noise detection.

[0086] In one example, the operational amplifier in the signal amplification module may be of the type LM7171, and the corresponding unit bandwidth gain product is . Input resistance can be set The resistance is 10kΩ, due to the conducted electromagnetic interference , you can set the effective bandwidth of the operational amplifier , then the magnification at this time , rounded down to get the amplification factor of 5, then the feedback resistance can be obtained kΩ. Then, verify that when the input resistance , feedback resistor The actual effective bandwidth , which can effectively cover the target frequency band of conducted electromagnetic interference. Please refer to the following table for the change of the gain of the operational amplifier with frequency. Figure 4 ,from Figure 4 As can be seen, within the frequency range of 50kHz to 10MHz, the gain remains essentially stable at approximately 14dB, indicating that the op amp's amplification capability is relatively constant within this frequency range. Above 10MHz, the gain begins to decrease, indicating that the amplification capability of the op amp gradually weakens with increasing frequency. The effective bandwidth refers to the point where the op amp's gain drops from constant to a 3dB decrease. From 50kHz to 30MHz, the op amp's gain only drops by 0.5dB, meaning the op amp's effective bandwidth covers 30MHz.

[0087] In step S4, see Figure 1 In step S4, the turns ratio of the transformer in the voltage injection module is determined according to the impedance mismatch principle and the amplification factor of the signal amplification module.

[0088] As an example, the equivalent impedance of the voltage compensation It can be seen that when When , the equivalent impedance of voltage compensation will be infinite, satisfying the impedance mismatch. In order to reduce the volume of the feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch, the voltage compensation coefficient can be designed Less than 1, when the voltage compensation coefficient When it is less than 1, the transformer has more primary turns and fewer secondary turns, and the transformer has fewer secondary turns than the primary turns. The transformer is close to the filter side as the primary side, and close to the main power side as the secondary side.

[0089] As an example, in the conducted electromagnetic interference frequency band, since the RC high-pass circuit has minimal attenuation on the signal in this frequency band, its transfer function is approximately 1, so the sampling coefficient H=1. According to the amplification factor G of the signal amplification module, the voltage compensation coefficient can be obtained. , voltage compensation coefficient Indicates the ratio of the turns on the main power side of the transformer to the turns on the filter side in the voltage injection module.

[0090] As an example, to make the EMI filter meet the impedance mismatch, the gain G and the transformer turns ratio need to be increased. , due to the transformer turns ratio Increasing the turns of the main power side of the transformer increases the volume of the transformer. In order to obtain the required turns ratio , the transformer main power side current is set to be large, the line diameter is thick, the filter side current is small, and the filter side line diameter is thin. The feedforward filter can be designed to have more turns than the main power side, thereby reducing the volume of the transformer of the voltage injection module, and the volume of the filter is mostly the transformer of the voltage injection module, thereby greatly reducing the volume of the filter.

[0091] In one example, when the amplification factor of the signal amplification module , the sampling coefficient of the voltage sampling module , the turns ratio of the transformer is , which means that the ratio of the turns of the main power side of the transformer of the voltage injection module to the turns of the filter side is 0.2, which means that the turns of the main power side are less than the turns of the filter side, and in actual use, the line diameter of the main power side of the transformer is larger than the line diameter of the filter side. Such a turns ratio can effectively reduce the volume of the filter.

[0092] In step S5, please refer to step S5 in Figure 1 , the compensation resistance value of the voltage injection module is determined according to the damping effect.

[0093] As an example, in order to suppress transformer resonance and avoid high-frequency noise amplification, a compensation resistance may be added to the voltage injection module . According to the damping effect, if the resistance of the compensation resistance is too small, the oscillation or resonance in the circuit cannot be effectively suppressed, which may cause the compensation link to work unstably; if the resistance of the compensation resistance is too large, it will affect the normal operation of the transformer. Therefore, a compromise value can be taken to balance the damping effect and the working state of the transformer, to ensure the stable operation of the voltage compensation, and thus to ensure the overall noise suppression effect of the electromagnetic interference filter.

[0094] In one example, considering the damping effect and the normal operation of the transformer, the compensation resistance may be set.

[0095] In step S6, please refer to step S6 in Figure 1 , the compensation capacitance value of the current injection module is determined according to the leakage constraint to complete the design of the electromagnetic interference filter.

[0096] As an example, according to the impedance mismatch principle, the current injection module should provide low impedance and be connected in parallel in the common-mode loop to form impedance mismatch with the noise source end. According to the equivalent impedance of the current compensation , it can be seen that the current compensation coefficient Essentially, it is the capacitive reactance characteristic of the capacitor, which means that the equivalent impedance of the current injection module is determined by the capacitive reactance characteristic of the capacitor. The capacitive reactance of the capacitor decreases with increasing frequency and can provide low impedance in the conducted electromagnetic interference frequency band. Therefore, the current injection module can be set as a compensation capacitor.

[0097] Furthermore, according to the safety standard AC peak voltage , leakage current and mains frequency , based on the leakage formula The maximum capacitance of the compensation capacitor can be obtained. In order to leave a margin, the capacitance of the compensation capacitor of the current injection module can be determined according to the maximum capacitance of the compensation capacitor. .

[0098] In one example, when the peak voltage , Earth leakage current , mains frequency According to the leakage formula The capacitance of the compensation capacitor can be obtained , taking into account the comprehensive consideration, a 20% margin can be taken, and the capacitance of the compensation capacitor can be set .

[0099] As an example, the design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter further includes step S7: designing a simulation experiment to verify the effectiveness of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter.

[0100] As an example, the Saber circuit simulation software can be used to build an overall circuit to simulate and verify the performance of the electromagnetic interference filter proposed in this application.

[0101] Specifically, first, the Saber simulation is run without adding any filter in the initial circuit, time domain results of original noise generated by the noise source end are obtained, and the FFT analysis function of Saber is used to obtain the frequency spectrum of the original noise. Then, the electromagnetic interference filter of the application is added in the initial circuit, the Saber simulation is run, the time domain results when the feed-forward voltage sampling double-compensation active electromagnetic interference filter based on impedance mismatch works are obtained, and the FFT analysis function of Saber is used to obtain the first frequency spectrum. Then, the traditional feed-forward voltage sampling current compensation type (FF-VSCC) active common mode electromagnetic interference filter is added in the initial circuit, the Saber simulation is run, the time domain results when the traditional feed-forward voltage sampling current compensation type active common mode electromagnetic interference filter works are obtained, and the FFT analysis function of Saber is used to obtain the second frequency spectrum. Then, the traditional feed-forward voltage sampling voltage compensation type (FF-VSVC) active common mode electromagnetic interference filter is added in the initial circuit, the Saber simulation is run, the time domain results when the feed-forward voltage sampling voltage compensation type active common mode electromagnetic interference filter works are obtained, and the FFT analysis function of Saber is used to obtain the third frequency spectrum.

[0102] Further, the first frequency spectrum is compared with the frequency spectrum of the original noise, the second frequency spectrum, and the third frequency spectrum respectively, and analysis is performed to realize simulation verification.

[0103] As an example, Figure 5 The first frequency spectrum is compared with the frequency spectrum of the original noise, the second frequency spectrum, and the third frequency spectrum respectively, and analysis is performed to realize simulation verification. Figure 6 The first frequency spectrum is compared with the frequency spectrum of the original noise, the second frequency spectrum, and the third frequency spectrum respectively, and analysis is performed to realize simulation verification. Figure 7 The first frequency spectrum is compared with the frequency spectrum of the original noise, the second frequency spectrum, and the third frequency spectrum respectively, and analysis is performed to realize simulation verification. Figures 5 to 7It can be seen that the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter of the present application has an insertion loss of 46.14dB at the second harmonic, which is significantly higher than the insertion loss caused by traditional feedforward voltage sampling current-compensation active common-mode electromagnetic interference filters and traditional feedforward voltage sampling voltage-compensation active common-mode electromagnetic interference filters in the low-frequency band. In addition, the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter of the present application also has a high insertion loss in the high-frequency band, while traditional single-compensation active common-mode electromagnetic interference filters (feedforward voltage sampling current-compensation type, feedforward voltage sampling voltage-compensation type) have lower insertion loss in the high-frequency band. This is because single-compensation active electromagnetic interference filters can only provide an equivalent impedance to attenuate noise and cannot form an impedance mismatch with the interfered end and the noise source end. It can be seen that the filtering effect of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter of the present application is significantly better than that of feedforward voltage sampling current-compensation type and feedforward voltage sampling voltage-compensation type active common-mode electromagnetic interference filters across the entire frequency band.

[0104] As an example, the simulation results show that the insertion loss value is approximately 46.14dB at the second harmonic, and the insertion loss value in the high frequency band is greater than 60dB, which fully demonstrates the effectiveness and practicality of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter of this application.

[0105] In the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter method of the present application, the RC high-pass characteristic is used to accurately match the cutoff frequency and impedance, so that the voltage sampling module can accurately capture broadband interference signals; the amplification factor is determined in combination with the unit gain bandwidth of the operational amplifier to avoid signal distortion while ensuring amplification accuracy; the transformer turns ratio is collaboratively designed through the impedance mismatch principle and the amplification factor to achieve efficient signal transmission and impedance matching optimization; by setting the voltage compensation coefficient to less than 1, the number of turns on the main power side of the transformer is small and the number of turns on the filter side is large, which can effectively reduce the volume of the electromagnetic interference filter. While achieving noise suppression, the present application reduces the impact on surrounding equipment. By using a feedforward dual compensation structure, an impedance mismatch is formed with the load impedance of the interfered end and the source impedance of the noise source end, which can greatly improve the voltage insertion loss of the electromagnetic interference filter in the full frequency band. Due to the special structure of the feedforward filter, the voltage compensation link can have fewer turns on the main power side and more turns on the filter side. Since the wire diameter on the main power side is thick and the wire diameter on the filter side is very thin, the volume of the filter is greatly reduced. The effective bandwidth can cover the conducted electromagnetic interference frequency band, and can adapt to the requirements of the new generation of power electronic equipment for small filter volume and high insertion loss, greatly optimizing the use of electromagnetic interference filters in power electronic equipment.

[0106] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The order of execution of these sub-steps or stages is not necessarily sequential, but can be executed in rotation or alternation with other steps or at least a portion of the sub-steps or stages of other steps.

[0107] In one embodiment, see Figure 8 The present application provides a feedforward voltage sampling dual-compensation active electromagnetic interference filter 1 based on impedance mismatch. The feedforward voltage sampling dual-compensation active electromagnetic interference filter 1 based on impedance mismatch is connected between an interfered terminal 2 and a noise source terminal 3 by applying the above-mentioned design method. The feedforward voltage sampling dual-compensation active electromagnetic interference filter 1 based on impedance mismatch comprises: a voltage sampling module 11, a signal amplification module 12, a current injection module 13, and a voltage injection module 14. A first end and a second end of the voltage sampling module 11 are connected in parallel between the noise source terminal 3. A third end of the voltage sampling module 11 is connected to a first end of the signal amplification module 12. A second end of the signal amplification module 12 is connected to a first end of the current injection module 13. A second end of the current injection module 13 is connected to a first end of the voltage injection module 14. A third end of the current injection module 13 is connected to a second end of the interfered terminal 2. A second end of the voltage injection module 14 is connected to a second end of the signal amplification module 12. A third end of the voltage injection module 14 is connected to a first end of the interfered terminal 2.

[0108] As an example, the voltage sampling module 11 , the signal amplifying module 12 , the current injection module 13 , and the voltage injection module 14 constitute a feedforward voltage sampling dual compensation structure.

[0109] As an example, the interfered end 2 may include an input power supply and a Line Impedance Stabilization Network (LISN). The input power supply may include an AC power supply or a DC power supply, and may input an AC signal or a DC signal.

[0110] As an example, the noise source end 3 may include an electrical device, a noise source, etc. The electrical device may be a DC electrical device or an AC electrical device.

[0111] As an example, the current injection module 13 is a current compensation branch, close to the noise source terminal 3 .

[0112] As an example, the voltage injection module 14 is a voltage compensation branch, close to the disturbed end 2.

[0113] As an example, the interference voltage V 干扰 , of the noise source end 3 is obtained by the voltage sampling module 11. 干扰 The obtained voltage V 补偿 is amplified by the signal amplification module 12 to enhance the signal strength for subsequent module processing. The current injection module 13 generates a compensation current I s to be injected into the common mode loop to offset or weaken the interference current generated by the noise source end; the voltage injection module 14 generates a compensation voltage according to the amplified signal, further suppresses the interference by means of voltage injection, and jointly acts to reduce the interference of the noise source end on the disturbed end, so that the disturbed end can work relatively stably.

[0114] As an example, please refer to Figure 9 , the voltage sampling module 11 includes resistors R s1 , capacitors C s2 , and capacitors C s1 . The first end of the capacitor C s1 is connected to the first end of the noise source end 3, the second end of the capacitor C s is connected to the first end of the resistor R s2 , the first end of the capacitor C s2 is connected to the second end of the noise source end 3, the second end of the capacitor C s is connected to the first end of the resistor R s , and the second end of the resistor R s1 is grounded through a heat sink and a chassis. The capacitance values of the capacitors C s2 and C s are both C .

[0115] As an example, the voltage sampling module 11 can be a first-order RC high-pass filter to realize detection of conducted electromagnetic interference in the conducted electromagnetic interference range.

[0116] As an example, please refer to Figure 9 , the signal amplification module 12 includes an operational amplifier U, resistors R g , and resistors R f . The first end of the resistor R g is connected to the second end of the capacitor C s1 , and the second end of the resistor R g is connected to the first input end of the operational amplifier U. The first end of the resistor R f is connected to the first input end of the operational amplifier U, and the second end of the resistor R fThe second end of is connected to the output end of the operational amplifier U. The second input end of the operational amplifier U is grounded through the heat sink and the housing. The signal amplification module 12 amplifies the noise source voltage obtained by the voltage sampling module 11 and outputs it.

[0117] As an example, the resistor R g It can be the input resistance, which determines the current size and other characteristics of the input signal of the operational amplifier U, and realizes the function of limiting the input current; the resistor R f It can be used as a feedback resistor to build a feedback loop by changing the input resistance R g With the feedback resistor R f The ratio can adjust the amplification factor of the operational amplifier U.

[0118] As an example, the first input terminal of the operational amplifier U may be an inverting input terminal, and the second input terminal of the operational amplifier U may be a non-inverting input terminal.

[0119] As an example, the model of the operational amplifier U may be LM7171.

[0120] As an example, see Figure 9 The current injection module 13 includes a capacitor C j1 With capacitor C j2 , capacitor C j1 The first end of the capacitor C is connected to the first end of the noise source terminal 3. j1 The second end is connected to the output of the operational amplifier U, and the capacitor C j2 The first end of the capacitor C is connected to the second end of the noise source terminal 3. j2 The second end is connected to the output of the operational amplifier U, and the capacitor C j1 With capacitor C j2 The capacitance value is C j .

[0121] As an example, see Figure 9 The voltage injection module 14 includes: a resistor R j and transformer T, resistor R j The first end of the transformer T is connected to the first end of the primary winding N1, and the resistor R j The second end of is connected to the output end of the operational amplifier U, the second end of the primary winding N1 of the transformer T is grounded, the first end of the secondary first winding N2 of the transformer T is connected to the second end of the noise source end 3, the second end of the secondary first winding N2 of the transformer T is connected to the second end of the interfered end 2, the first end of the secondary second winding N3 of the transformer T is connected to the first end of the noise source end 3, and the second end of the secondary second winding N3 of the transformer T is connected to the first end of the interfered end 2.

[0122] As an example, the transformer T can be a three-winding transformer, and the resistor R jCan be a compensation resistor.

[0123] As an example, the first secondary winding N2 and the second secondary winding N3 of the transformer T are the main power side, and the primary winding N1 of the transformer T is the filter side. The transformer T can be set to have fewer turns on the main power side and more turns on the filter side. The number of turns on the secondary side of the transformer is smaller than the number of turns on the primary side, and the secondary side wire diameter of the transformer is larger than the primary side wire diameter, so as to reduce the volume of the electromagnetic interference filter.

[0124] As an example, the structure of the feedforward voltage sampling dual compensation active electromagnetic interference filter 1 based on impedance mismatch is similar to a passive filter of LC structure from the perspective of the interfered end to the noise source end. It can form an impedance mismatch with the impedance of the interfered end and the noise source end without introducing large-volume traditional passive components, thereby realizing the role of a passive filter to a certain extent and having a significant inhibitory effect on noise signals. The feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch of the present application is suitable for filtering common-mode noise. By setting two compensation loops, the equivalent impedance formed by the two compensation loops satisfies the impedance mismatch with the noise source end and the interfered end respectively. Compared with the traditional active electromagnetic interference filter, the insertion loss of the filter can be significantly improved. The electromagnetic interference filter of the present application has a large effective bandwidth, can attenuate noise within the range of conducted electromagnetic interference, and can achieve the advantages of small size and high insertion loss without the need for additional passive filtering components. While satisfying the impedance mismatch, it can ensure that the volume is significantly smaller than that of the traditional passive filter, and because the number of turns on the main power side of the transformer is small, the volume of the transformer is reduced.

[0125] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] Although the present application has been disclosed above with reference to the embodiments, they are not intended to limit the present application. Anyone with ordinary knowledge in the technical field may make slight changes and modifications without departing from the spirit and scope of the present application.

Claims

1. A design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, characterized in that: The following steps are involved: An equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is constructed according to an impedance mismatch principle, and a circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is determined according to the equivalent circuit, wherein the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module; The structure of the voltage sampling module is determined according to the RC high-pass property, and the resistance value and capacitance of the voltage sampling module are determined according to the cutoff frequency and impedance of the RC high-pass circuit; Determine the operational amplifier model of the signal amplification module and the effective bandwidth required by the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter, and determine the amplification factor of the signal amplification module based on the unit gain bandwidth and effective bandwidth of the operational amplifier model; Determine the turns ratio of the transformer in the voltage injection module according to the impedance mismatch principle and the amplification factor of the signal amplification module; Determine the compensation resistance value of the voltage injection module according to the damping effect; The compensation capacitance value of the current injection module is determined according to the leakage constraint, and the design of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is completed.

2. The design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 1, characterized in that: According to the impedance mismatch principle, an equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is constructed, and a circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is determined according to the equivalent circuit. The feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module, including: According to the impedance mismatch principle, an equivalent circuit of a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is constructed, and the equivalent impedance of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is determined; According to the impedance mismatch principle and the equivalent impedance of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, the positions and equivalent impedance values ​​of voltage compensation and current compensation are determined respectively; The equivalent circuit of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter is decomposed into functional modules to obtain the circuit topology of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter. The impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter includes a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module.

3. The design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 2, characterized in that: According to the impedance mismatch principle and the equivalent circuit of the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, the positions and equivalent impedance values ​​of the voltage compensation and current compensation are determined, including, according to the impedance mismatch principle, setting the voltage compensation in series in the noise loop, the voltage compensation being close to the interfered end, and forming an impedance mismatch with the interfered end; The current compensation is set in parallel in the noise loop. The current compensation is close to the noise source end and forms an impedance mismatch with the noise source end. The equivalent impedance of voltage compensation is , the expression is: in, is the voltage compensation coefficient, is the load impedance at the interfered end, G is the magnification, H represents the sampling coefficient; The equivalent impedance of current compensation is , the expression is: in, is the current compensation coefficient, G is the magnification, H Indicates the sampling factor.

4. The design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 3, characterized in that: Since the impedance value of the interfered end is small, a high impedance should be connected in series to meet the impedance mismatch requirement. v GH=1, the equivalent impedance Z of voltage compensation v is a high impedance, which satisfies the impedance mismatch and obtains the voltage compensation coefficient k v =1 / GH, which is the transformer turns ratio.

5. The design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 4, characterized in that: Set the secondary side turns of the transformer in the voltage injection module to be smaller than the primary side turns; set the secondary side wire diameter of the transformer in the voltage injection module to be larger than the primary side wire diameter to meet the voltage compensation coefficient k v At the same time, the filter size is reduced.

6. The design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 1, characterized in that: Determine the operational amplifier model of the signal amplification module and the effective bandwidth required by the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter, and determine the amplification factor of the signal amplification module based on the unit gain bandwidth and effective bandwidth of the operational amplifier model, including selecting the operational amplifier according to the effective bandwidth requirement, determining the unit bandwidth gain product of the operational amplifier according to the operational amplifier model, determining the amplification factor that meets the effective bandwidth requirement based on the unit bandwidth gain product of the operational amplifier, and determining the resistance values ​​of the input resistor and the feedback resistor according to the amplification factor.

7. The design method of the impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 1, characterized in that: Determine the compensation capacitor value of the current injection module according to the leakage constraint and complete the design of the electromagnetic interference filter, including setting the current injection module as the compensation capacitor according to the equivalent impedance of the current compensation; setting the AC peak voltage according to the safety standard , leakage current and mains frequency , based on the leakage formula Get the maximum capacitance of the compensation capacitor; determine the capacitance of the compensation capacitor in the current injection module based on the maximum capacitance of the compensation capacitor .

8. A feedforward voltage sampling dual compensation active electromagnetic interference filter based on impedance mismatch, characterized in that: A design method for a feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch, applied to any one of claims 1 to 7, wherein the feedforward voltage sampling dual-compensation active electromagnetic interference filter based on impedance mismatch is connected between an interfered end and a noise source end, and comprises: a voltage sampling module, a signal amplification module, a current injection module, and a voltage injection module, wherein a first end and a second end of the voltage sampling module are connected in parallel between the noise source ends, a third end of the voltage sampling module is connected to a first end of the signal amplification module, a second end of the signal amplification module is connected to a first end of the current injection module, a second end of the current injection module is connected to a first end of the voltage injection module, a third end of the current injection module is connected to a second end of the interfered end, a second end of the voltage injection module is connected to a second end of the signal amplification module, and a third end of the voltage injection module is connected to a first end of the interfered end.

9. The impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 8, characterized in that: The voltage injection module is close to the interfered end, and the equivalent impedance of the voltage injection module is large, forming an impedance mismatch with the interfered end; the current injection module is close to the noise source end, and the equivalent impedance of the current injection module is small, forming an impedance mismatch with the noise source end.

10. The impedance mismatch-based feedforward voltage sampling dual-compensation active electromagnetic interference filter according to claim 8, characterized in that: The voltage sampling module, the signal amplifying module, the current injection module and the voltage injection module constitute a feedforward voltage sampling double compensation structure.

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