A voltage probe for detecting electromagnetic interference

Abstract

The utility model discloses a voltage probe for detecting electromagnetic interference belongs to electromagnetic compatibility technical field. Voltage probe includes high pass filter circuit, interference detection circuit, the input of voltage probe is connected with the output of voltage probe in proper order through high pass filter circuit, interference detection circuit, voltage probe includes first electric capacity, second electric capacity, first inductance high pass filter circuit, the input is connected in series with second electric capacity, first electric capacity in proper order, and one end of first inductance is connected in the middle of first electric capacity and second electric capacity, and the other end is grounded, interference detection circuit includes first resistance, and first resistance is connected between first electric capacity and output terminal in series, the cut-off frequency of high pass filter circuit is less than 9kHz. Through the input of voltage probe and access cut-off frequency less than 9kHz's high pass filter circuit, has increased the attenuation factor of low frequency band, has strengthened the suppression ability to low frequency band interference signal, prevents the resistance in voltage probe and appears overload damage, has expanded the application scene of voltage probe.

Description

Technical Field

[0001] This utility model relates to the field of electromagnetic compatibility technology, and in particular to a voltage probe for detecting electromagnetic interference. Background Technology

[0002] In the field of electromagnetic compatibility testing, conducted emissions testing is a key test item for evaluating the degree of electromagnetic interference caused to the power supply network by electronic and electrical equipment under normal operating conditions. According to relevant international standards, an artificial power network is usually used as the standard measuring device to separate the common-mode interference signal between the device under test and the power supply system, and to provide a standardized 50Ω impedance matching interface for the receiver.

[0003] However, when dealing with high-power, high-voltage, or high-current devices under test, traditional artificial power networks often fail to meet testing requirements due to their rated voltage and current limitations. In such cases, standards explicitly state that EMI (Electromagnetic Interference) voltage probes can be used to replace artificial power networks for conducted emission testing. Therefore, EMI voltage probes are widely used in EMI testing of power electronic equipment, industrial control systems, and new energy converters, becoming an indispensable key measurement tool for such testing.

[0004] Currently, common voltage probe circuit structures used in the industry for detecting electromagnetic interference include: Figure 1 As shown, its basic components include: DC blocking capacitor C1(X) C1 <1500Ω), current-limiting resistor R1 (R1=(1500–R)Ω) and grounding protection inductor L(X L >R). The probe's input terminal 3 is connected in parallel between the power supply port of the device under test and the protective ground, while the output terminal 4 is connected to the EMI receiver 5. The DC blocking capacitor C1 provides high capacitive reactance under DC or AC power frequency conditions, effectively preventing large currents from passing through the probe; and within the EMI target frequency band of 9kHz to 30MHz, its capacitive reactance is much less than 1500Ω, giving the probe a stable attenuation factor across the entire target frequency range, thus enabling accurate measurement of conducted emission voltage.

[0005] Although the EMI voltage probes with the above-described structure have been widely accepted in practical applications, they still have significant technical drawbacks in certain application scenarios. For example... Figure 2 As shown, Figure 2 It shows Figure 1The graph shows the attenuation factor variation trend of the voltage probe in the 1kHz-30MHz frequency band. Currently, the attenuation factor of EMI voltage probes is relatively small in some low-frequency bands. For example, the attenuation factor at 2kHz is only 45dB. For some devices with low switching frequency but high interference energy (such as low-frequency inverters, frequency converters, wind power converters, etc.), the current limiting resistor R1 inside the probe will bear a large low-frequency interference current, which will cause heat generation or even burn out, affecting the service life of the probe and the reliability of the test.

[0006] In summary, while existing EMI voltage probes can maintain good attenuation consistency in the 9kHz to 30MHz frequency band, their attenuation capability is weak in the low-frequency band below 9kHz, making it difficult to cope with the overload risk posed by high-energy low-frequency interference. Therefore, there is an urgent need to propose an improved EMI voltage probe structure that, while maintaining stable attenuation performance in the high-frequency band, enhances the suppression capability of low-frequency interference signals, thereby improving the probe's applicability and safety. Utility Model Content

[0007] This invention addresses the aforementioned problems in the prior art by providing a voltage probe for detecting electromagnetic interference. While maintaining the original stable attenuation performance in the high-frequency band, it enhances the ability to suppress interference signals in the low-frequency band, thereby improving the applicability and safety of the probe.

[0008] This utility model provides a voltage probe for detecting electromagnetic interference, including a high-pass filter circuit and an interference detection circuit;

[0009] The input terminal of the voltage probe is connected to the output terminal of the voltage probe in sequence via the high-pass filter circuit and the interference detection circuit;

[0010] The high-pass filter circuit includes a first capacitor, a second capacitor, and a first inductor; the input terminal is connected in series with the second capacitor and the first capacitor in sequence, one end of the first inductor is connected between the first capacitor and the second capacitor, and the other end is grounded;

[0011] The interference detection circuit includes a first resistor, which is connected in series between the first capacitor and the output terminal;

[0012] The cutoff frequency of the high-pass filter circuit is less than 9kHz.

[0013] A high-pass filter circuit with a cutoff frequency of less than 9kHz is added to the input of the voltage probe, increasing the attenuation factor in the frequency band below 9kHz and enhancing the suppression of low-frequency interference signals, preventing overload damage to the resistors in the voltage probe. This improvement is particularly suitable for measuring devices with low switching frequencies but high interference energy, extending the probe's lifespan and improving test reliability. Simultaneously, the original high-frequency band maintains stable attenuation performance. This dual-band optimized design ensures that the probe provides consistent and reliable measurement results across the entire conducted emission test frequency band, meeting stringent EMC standards.

[0014] In the voltage probe for detecting electromagnetic interference provided by this utility model, the equivalent capacitance of the first capacitor and the second capacitor connected in series is 10nF.

[0015] In the voltage probe for detecting electromagnetic interference provided by this utility model, the capacitance values ​​of the first capacitor and the second capacitor, and the inductance value of the first inductor are determined according to the target attenuation factor.

[0016] Based on the target attenuation factor and the attenuation factor formula, the parameters of the first capacitor, the second capacitor, and the first inductor can be selected so that the selected components are as close as possible to the expected target attenuation factor, thereby controlling the current in the circuit and avoiding resistor overload.

[0017] The equivalent capacitance of the first capacitor and the second capacitor connected in series is 10nF, which is the same as the commonly used capacitance value of DC blocking capacitors in traditional circuits. This configuration enables the first capacitor and the second capacitor to provide high capacitive reactance under DC or AC power frequency to prevent large current from flowing through.

[0018] The voltage probe for detecting electromagnetic interference provided by this utility model further includes a grounding protection inductor in the interference detection circuit. One end of the grounding protection inductor is connected to the output terminal, and the other end is grounded.

[0019] Grounding protection inductors are used to prevent high-frequency interference signals from being directly grounded, provide appropriate impedance matching, enhance anti-interference capabilities, and protect subsequent circuits.

[0020] The voltage probe for detecting electromagnetic interference provided by this utility model further includes a second resistor in the interference detection circuit. One end of the second resistor is connected to the output terminal, and the other end is grounded.

[0021] The impedance of a resistor is relatively stable across any frequency band, while the inductive reactance of an inductor decreases as the signal frequency decreases, leading to a reduction in protection capability. Therefore, using a second resistor instead of a grounding protection inductor can effectively improve the safety of the probe.

[0022] The voltage probe for detecting electromagnetic interference provided by this utility model further includes a third capacitor and a second inductor in the high-pass filter circuit.

[0023] The third capacitor is connected between the input terminal and the second capacitor, and one end of the second inductor is connected between the second capacitor and the third capacitor, while the other end is grounded.

[0024] The first capacitor, the second capacitor, the third capacitor, the first inductor, and the second inductor constitute a second-order T-type high-pass filter circuit, which is also used to suppress low-frequency interference.

[0025] In the voltage probe for detecting electromagnetic interference provided by this utility model, the equivalent capacitance of the first capacitor, the second capacitor and the third capacitor connected in series is 10nF.

[0026] The equivalent capacitance of the first, second, and third capacitors connected in series is 10nF, which is the same as the commonly used capacitance value of DC blocking capacitors in traditional circuits. It can provide high capacitive reactance to prevent large current from flowing through DC or AC power frequency.

[0027] In the voltage probe for detecting electromagnetic interference provided by this utility model, the capacitance values ​​of the first capacitor, the second capacitor, and the third capacitor, and the inductance values ​​of the first inductor and the second inductor are determined according to the target attenuation factor.

[0028] Based on the target attenuation factor and the attenuation factor formula, the parameters of the first capacitor, second capacitor, third capacitor, first inductor, and second inductor can be selected so that the selected components are as close as possible to the expected target attenuation factor, thereby controlling the current in the circuit and avoiding resistor overload.

[0029] The voltage probe for detecting electromagnetic interference provided by this utility model further includes a shielding shell that surrounds the high-pass filter circuit and the interference detection circuit.

[0030] The shielding shell reduces the impact of external electromagnetic interference on the voltage probe, improving the accuracy of the measurement.

[0031] The voltage probe for detecting electromagnetic interference provided by this utility model further includes an adjustable attenuator, which is disposed between the interference detection circuit and the output terminal to adjust the signal amplitude as needed.

[0032] Adjustable attenuators can prevent signals from being too strong or too weak, enhancing the flexibility of the system. Attached Figure Description

[0033] Figure 1This is a schematic diagram of the circuit structure of a voltage probe for detecting electromagnetic interference in the prior art.

[0034] Figure 2 for Figure 1 The corresponding attenuation factor trend graph of the voltage probe used to detect electromagnetic interference.

[0035] Figure 3 This is a schematic diagram of the circuit structure of a voltage probe for detecting electromagnetic interference, provided as the first embodiment of the present invention.

[0036] Figure 4 for Figure 3 The corresponding attenuation factor trend graph of the voltage probe used to detect electromagnetic interference.

[0037] Figure 5 This is a schematic diagram of the circuit structure of a voltage probe for detecting electromagnetic interference, provided as a second embodiment of the present invention.

[0038] Figure 6 for Figure 5 The corresponding attenuation factor trend graph of the voltage probe used to detect electromagnetic interference.

[0039] Figure 7 This is a schematic diagram of the circuit structure of a voltage probe for detecting electromagnetic interference, provided as a third embodiment of the present invention.

[0040] Figure 8 for Figure 7 The corresponding attenuation factor trend graph of the voltage probe used to detect electromagnetic interference.

[0041] Figure 9 This is a schematic diagram of the circuit structure of a voltage probe for detecting electromagnetic interference, provided as a fourth embodiment of the present invention.

[0042] Figure 10 for Figure 9 The corresponding attenuation factor trend graph of the voltage probe used to detect electromagnetic interference.

[0043] In the attached diagram:

[0044] 1. High-pass filter circuit; 2. Interference detection circuit; 3. Input terminal; 4. Output terminal; 5. EMI receiver. Detailed Implementation

[0045] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0046] The "voltage probe for detecting electromagnetic interference" mentioned in this article is what the industry calls an "EMI voltage probe." Figure 1The diagram shows a commonly used circuit structure for voltage probes used in the industry to detect electromagnetic interference. The DC blocking capacitor C1 is typically chosen to have a capacitance of 10nF, and the resistor R is a sampling voltage divider resistor within the EMI receiver, with a resistance of 50Ω. The inventor adopted... Figure 1 The voltage probe shown is used to perform common-mode conducted emissions testing between the main power port and ground of a wind power converter. The commonly used switching frequency of wind power converters is 2kHz. The product's machine side uses a PWM-controlled full-bridge inverter, and the peak common-mode voltage typically ranges from 1000V to 2000V. The above test scenario is a typical low-frequency, high-energy scenario. Figure 1 The formula for calculating the attenuation factor of a medium-voltage probe is as follows:

[0047] in: Vin is the voltage value at input terminal 3, and Vout is the voltage value at output terminal 4. (Formula 1)

[0048] Figure 2 According to Figure 1 The simulation results of the circuit diagram shown indicate that the voltage probe attenuates by only 45dB at 2kHz. Figure 1 The voltage probe shown is used in this test scenario, which will inevitably cause the first resistor R1 to bear a large low-frequency interference current, resulting in heat generation or even burnout.

[0049] In order to make Figure 1 The voltage probe shown enhances the suppression of low-frequency interference signals while maintaining stable attenuation performance in the high-frequency band, thereby improving the probe's applicability and safety. This invention provides a voltage probe for detecting electromagnetic interference. Specific embodiments are described below.

[0050] Example 1

[0051] This utility model embodiment provides a voltage probe for detecting electromagnetic interference, the circuit structure of which is as follows: Figure 3 As shown, it includes a high-pass filter circuit 1 and an interference detection circuit 2;

[0052] The input terminal 3 of the voltage probe is connected to the output terminal 4 of the voltage probe in sequence via a high-pass filter circuit 1 and an interference detection circuit 2.

[0053] The high-pass filter circuit 1 includes a first capacitor C1, a second capacitor C2, and a first inductor L1; the input terminal 3 is connected in series with the second capacitor C2 and the first capacitor C1 in sequence, and one end of the first inductor L1 is connected between the first capacitor C1 and the second capacitor C2, and the other end is grounded.

[0054] The interference detection circuit 2 includes a first resistor R1, which is connected in series between the first capacitor C1 and the output terminal 4.

[0055] The cutoff frequency of the high-pass filter circuit 1 is less than 9kHz.

[0056] In this embodiment of the invention, a high-pass filter circuit with a cutoff frequency of less than 9kHz is connected to the input terminal of the voltage probe. This increases the attenuation factor in the frequency band below 9kHz, enhances the suppression capability of low-frequency interference signals, and prevents overload damage to the resistors in the voltage probe. This improvement is particularly suitable for measuring devices with low switching frequencies but high interference energy, extending the probe's lifespan and improving test reliability. Simultaneously, the original high-frequency band maintains stable attenuation performance. This dual-band optimized design ensures that the probe provides consistent and reliable measurement results across the entire conducted emission test frequency band, meeting stringent EMC standard requirements.

[0057] like Figure 3 As shown, the interference detection circuit 2 also includes a grounding protection inductor L, one end of which is connected to the output terminal 4, and the other end is grounded.

[0058] Grounding protection inductors are used to prevent high-frequency interference signals from being directly grounded, provide appropriate impedance matching, enhance anti-interference capabilities, and protect subsequent circuits.

[0059] Adopting such Figure 3 When the voltage probe shown is used for electromagnetic interference measurement, the input terminal is connected in parallel between the test port of the device under test and the protective ground of the device under test, and the output terminal is connected to the EMI receiver.

[0060] Voltage probes used for detecting electromagnetic interference are typically used in situations where space is limited, such as when clamped to the input port of a prototype. Therefore, the smaller the probe, the easier it is to use. Figure 3 In the circuit, the first capacitor C1, the second capacitor C2, and the first inductor L form a T-type high-pass filter circuit, which is equivalent to replacing the filter capacitor of the high-pass filter circuit with the original capacitor. Figure 1 The DC blocking capacitor in the circuit performs both filtering and DC blocking functions, thus realizing the integration of a high-pass filter circuit with... Figure 1 The nesting of existing circuit structures reduces the number of components and the size of the probe.

[0061] In this embodiment, the equivalent capacitance of the first capacitor C1 and the second capacitor C2 connected in series is 10nF. Figure 1 The DC blocking capacitor C1 in the first capacitor has the same common capacitance value. This setting allows the first capacitor C1 and the second capacitor C2 to provide high capacitive reactance under DC or power frequency AC conditions to prevent large current from flowing through.

[0062] Theoretically, the cutoff frequency of a high-pass filter circuit can be made as close to 9kHz as possible. However, when selecting parameters, the equivalent capacitance of the first capacitor C1 and the second capacitor C2 connected in series needs to be 10nF. Therefore, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 are usually kept constant. To increase the cutoff frequency, the inductance value of the first inductor L1 needs to be reduced. If the inductance value of the first inductor L1 is too small, the attenuation factor in the frequency band above 9kHz will not meet the probe calibration requirements. Therefore, in selecting the parameters of the high-pass filter circuit, it is necessary to maximize the attenuation factor in the low-frequency band while ensuring the stability of the attenuation factor in the frequency band above 9kHz.

[0063] In the low-frequency range below 9kHz, the attenuation factor of the probe is determined by the high-pass filter circuit consisting of the first capacitor C1, the second capacitor C2, and the first inductor L1, as well as the impedance R1 of the probe itself. Above 9kHz, the attenuation of the high-pass filter circuit drops to 0. Therefore, the attenuation factor above 9kHz is determined only by the impedance R1 of the probe itself. Thus, even with the addition of a high-pass filter circuit, a stable attenuation factor can still be maintained above 9kHz.

[0064] In this embodiment, the formula for calculating the attenuation factor of the voltage probe is as follows:

[0065] in: (Formula 2)

[0066] In this embodiment, the capacitance values ​​of the first capacitor C1 and the second capacitor C2, and the inductance value of the first inductor L1 are determined according to the target attenuation factor.

[0067] Based on the target attenuation factor and the attenuation factor formula (Formula 2), the parameters of the first capacitor, the second capacitor, and the first inductor can be selected to ensure that the selected components are as close as possible to the expected target attenuation factor. This allows for control of the current in the circuit and avoids resistor overload. Alternatively, the selected component parameters can be substituted into Formula 2 to calculate the actual attenuation factor.

[0068] In this embodiment, the capacitance values ​​of the first capacitor C1 and the second capacitor C2 are both 22nF, and the inductance value of the first inductor L1 is 20mH. Therefore, the cutoff frequency of the high-pass filter circuit composed of these three capacitors is... The inductance value of the grounding protection inductor L is also taken as 20mH. For example... Figure 4 As shown, at 2kHz, the attenuation factor is relative to Figure 1 The voltage probe structure shown increases the current by 15dB, from 45dB to 60dB, significantly reducing the current across the first resistor R1 and lowering the risk of the first resistor R1 being damaged due to overheating.

[0069] In this embodiment, the voltage probe further includes a shielding housing that surrounds the high-pass filter circuit 1 and the interference detection circuit 2. The shielding housing reduces the impact of external electromagnetic interference on the voltage probe, improving measurement accuracy.

[0070] Optionally, the voltage probe further includes an adjustable attenuator, which is disposed between the interference detection circuit and the output terminal to adjust the signal amplitude as needed, avoiding problems of excessively strong or weak signals and enhancing the flexibility of the system.

[0071] Example 2

[0072] like Figure 5 As shown, in this embodiment, the interference detection circuit 2 further includes a second resistor R2, one end of which is connected to the output terminal 4, and the other end is grounded.

[0073] The difference between Example 2 and Example 1 is that a second resistor R2 is used instead of the grounding protection inductor L. The impedance of a resistor is relatively stable across any frequency band, while the inductance of an inductor decreases as the signal frequency decreases, leading to a reduction in protection capability. Therefore, using a second resistor R2 instead of the grounding protection inductor L can effectively improve the probe's safety.

[0074] To avoid affecting the attenuation factor, the resistance value of the second resistor R2 needs to be much larger than the 50Ω resistance value of the sampling voltage divider resistor in the EMI receiver. In this embodiment, the resistance value of the second resistor R2 is 875Ω. Figure 6 As shown in Example 2, the attenuation factor is still 60dB at 2kHz.

[0075] Example 3

[0076] like Figure 7 As shown, in this embodiment, the high-pass filter circuit further includes a third capacitor C3 and a second inductor L2; the third capacitor C3 is connected between the input terminal 3 and the second capacitor C2, one end of the second inductor L2 is connected between the second capacitor C2 and the third capacitor C3, and the other end is grounded.

[0077] The difference between Embodiment 3 and Embodiment 1 is that a third capacitor C3 and a second inductor L2 are added between the input terminal and the second capacitor C2. The first capacitor C1, the second capacitor C2, the third capacitor C3, the first inductor L1, and the second inductor L2 constitute a second-order T-type high-pass filter circuit, which is also used to suppress low-frequency interference.

[0078] In this embodiment, the equivalent capacitance of the series connection of the first capacitor C1, the second capacitor C2, and the third capacitor C3 is 10nF. Figure 1The commonly used capacitance value of the DC blocking capacitor C1 is the same, which can provide high capacitive reactance to prevent large current from flowing under DC or power frequency AC conditions.

[0079] In this embodiment, the formula for calculating the attenuation factor of the voltage probe is as follows:

[0080] in: (Formula 3)

[0081] In this embodiment, the capacitance values ​​of the first capacitor C1, the second capacitor C2, and the third capacitor C3, as well as the inductance values ​​of the first inductor L1 and the second inductor L2, are determined according to the target attenuation factor.

[0082] Based on the target attenuation factor and the attenuation factor formula (Formula 3), the parameters of the first capacitor, second capacitor, third capacitor, first inductor, and second inductor can be selected to ensure that the selected components are as close as possible to the expected target attenuation factor. This allows for control of the current in the circuit and avoids resistor overload. Alternatively, the selected component parameters can be substituted into Formula 3 to calculate the actual attenuation factor.

[0083] In this embodiment, the capacitance values ​​of the first capacitor C1, the second capacitor C2, and the third capacitor C3 are all 33nF, and the inductance values ​​of the first inductor L1 and the second inductor L2 are 20mH. Therefore, the cutoff frequency of the high-pass filter circuit composed of these five capacitors is... The inductance value of the grounding protection inductor L is also taken as 20mH. For example... Figure 8 As shown, at 2kHz, the attenuation factor is relative to Figure 3 The voltage probe structure shown has been improved by 11dB, reaching 71dB. Theoretically, adding multiple stages of high-pass filter circuits can achieve a larger attenuation factor; however, this may also lead to increased size and cost. In engineering practice, the number of stages of the high-pass filter circuit is determined based on specific needs.

[0084] Example 4

[0085] like Figure 9 As shown, the difference between Embodiment 4 and Embodiment 3 is that the second resistor R2 is used instead of the grounding protection inductor L.

[0086] In this embodiment, the resistance value of the second resistor R2 is the same as that in Embodiment 2, which is 875Ω.

[0087] like Figure 10 As shown in Example 4, the attenuation factor is still 71dB at 2kHz.

[0088] It is understandable that in the above embodiments, since the commonly used switching frequency in the test scenario is 2kHz, the focus is on the attenuation factor at 2kHz. For other low frequency bands below 9kHz, the principle is the same as this solution. The component parameters of the high-pass filter circuit are finely adjusted according to the main interference frequency band in the test. Under the premise of maintaining the original high-frequency stable attenuation factor of the voltage probe, the attenuation factor of the main interference frequency band is increased as much as possible.

[0089] This novel voltage probe not only enables conducted emission testing on high-power or high-voltage equipment that is incompatible with traditional artificial power networks, but also covers a wider frequency range, including low-frequency interference that was previously difficult to handle. This greatly expands the application scenarios of the voltage probe, making it suitable for more types of electronic and electrical equipment.

[0090] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit and scope of the claims. All of these modifications are within the protection scope of the present invention.

Claims

1. A voltage probe for detecting electromagnetic interference, characterized in that, Includes a high-pass filter circuit (1) and an interference detection circuit (2); The input terminal (3) of the voltage probe is connected to the output terminal (4) of the voltage probe in sequence via the high-pass filter circuit (1) and the interference detection circuit (2); The high-pass filter circuit (1) includes a first capacitor (C1), a second capacitor (C2), and a first inductor (L1); the input terminal (3) is connected in series with the second capacitor (C2) and the first capacitor (C1) in sequence, and one end of the first inductor (L1) is connected between the first capacitor (C1) and the second capacitor (C2), and the other end is grounded; The interference detection circuit (2) includes a first resistor (R1), which is connected in series between the first capacitor (C1) and the output terminal (4); The cutoff frequency of the high-pass filter circuit (1) is less than 9kHz.

2. A voltage probe for detecting electromagnetic interference according to claim 1, characterized in that, The equivalent capacitance of the first capacitor (C1) and the second capacitor (C2) connected in series is 10nF.

3. A voltage probe for detecting electromagnetic interference according to claim 2, characterized in that, The capacitance values ​​of the first capacitor (C1) and the second capacitor (C2), and the inductance value of the first inductor (L1) are determined according to the target attenuation factor.

4. A voltage probe for detecting electromagnetic interference according to claim 1, characterized in that, The interference detection circuit (2) further includes a ground protection inductor (L), one end of which is connected to the output terminal (4), and the other end is grounded.

5. A voltage probe for detecting electromagnetic interference according to claim 1, characterized in that, The interference detection circuit (2) further includes a second resistor (R2), one end of which is connected to the output terminal (4), and the other end is grounded.

6. A voltage probe for detecting electromagnetic interference according to any one of claims 1 to 5, characterized in that, The high-pass filter circuit (1) also includes a third capacitor (C3) and a second inductor (L2); The third capacitor (C3) is connected between the input terminal (3) and the second capacitor (C2). One end of the second inductor (L2) is connected between the second capacitor (C2) and the third capacitor (C3), and the other end is grounded.

7. A voltage probe for detecting electromagnetic interference according to claim 6, characterized in that, The equivalent capacitance of the first capacitor (C1), the second capacitor (C2), and the third capacitor (C3) connected in series is 10nF.

8. A voltage probe for detecting electromagnetic interference according to claim 7, characterized in that, The capacitance values ​​of the first capacitor (C1), the second capacitor (C2), and the third capacitor (C3), and the inductance values ​​of the first inductor (L1) and the second inductor (L2) are determined according to the target attenuation factor.

9. A voltage probe for detecting electromagnetic interference according to claim 1, characterized in that, The voltage probe also includes a shielded housing that surrounds the high-pass filter circuit (1) and the interference detection circuit (2).

10. A voltage probe for detecting electromagnetic interference according to claim 1, characterized in that, The voltage probe also includes an adjustable attenuator, which is located between the interference detection circuit (2) and the output terminal (4) to adjust the signal amplitude as needed.

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