Interference waveform output state monitoring system and monitoring method

Abstract

The present invention discloses an interference waveform output state monitoring system, comprising a signal coupling unit, a high-pass filtering unit, a trigger circuit unit and an early warning unit connected in sequence; the signal coupling unit is used to couple out the interference signal output by the test generator and the common-mode interference signal generated when the tested device is working; the high-pass filtering unit is used to filter out the low-frequency common-mode signal of the tested device working normally, and retain the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields; the trigger circuit unit is used to compare the maximum amplitude of the filtered signal with a set threshold value, and if the maximum amplitude of the signal is higher than the set threshold value, a trigger signal is generated; the early warning unit is used to alarm when receiving the trigger signal, indicating that there is an interference signal output. The present invention has the advantages of simple structure, convenient installation, convenient carrying and high test efficiency.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of interference testing, and in particular to an interference waveform output state monitoring system and a monitoring method. Background Art

[0002] Electromagnetic compatibility immunity test items, such as: electrical fast transient pulse group immunity, surge (impact) immunity, radio frequency field induced conducted disturbance immunity and other tests, are important contents of the electromagnetic compatibility performance assessment of the tested electrical and electronic equipment, and mainly examine the reliability and stability of electrical and electronic equipment working in complex electromagnetic environments. Among them, the international standard for electrical fast transient pulse group immunity test is IEC61000-4-4, and the equivalent national standard is GB / T17626.4; the international standard for surge (impact) immunity test is IEC61000-4-5, and the equivalent national standard is GB / T17626.5; the international standard for radio frequency field induced conducted disturbance immunity test is IEC61000-4-6, and the equivalent national standard is GB / T17626.6.

[0003] At present, most of the test equipment used for the above immunity test items, namely the test generator, do not have a built-in interference output detection device. This means that the test generator interference output needs to be measured and confirmed before and after each test, which seriously hinders the test efficiency; if the test generator interference output is not measured and confirmed, it will be impossible to ensure whether there is interference waveform output during the experiment, which will affect the reliability of the test conclusion. If the current conventional oscilloscope is used to monitor the waveform, its connection is complicated, the adjustment is slow, and it is not easy to move.

[0004] The terms are explained as follows: Electromagnetic compatibility: refers to the ability of a device or system to work normally in the electromagnetic environment in which it is located without causing interference to other devices and systems. Electrical fast transient pulse group: simulates the resistance of electrical and electronic equipment to various types of transient disturbances such as those from switching transient processes (cutting off inductive loads, relay contact bounce, etc.). Surge: simulates power system switching transients and lightning transients, which are high in energy and highly destructive. Conducted disturbance induced by radio frequency fields: the simulated disturbance source is the electromagnetic field from the radio frequency transmitter. Immunity: the ability of a device, equipment or system to face electromagnetic disturbances without reducing operating performance. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the problems existing in the prior art, the present invention provides an interference waveform output state monitoring system and a monitoring method with simple structure, convenient installation and high test efficiency.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] An interference waveform output state monitoring system comprises a signal coupling unit, a high-pass filtering unit, a trigger circuit unit and an early warning unit which are connected in sequence;

[0008] The signal coupling unit is used to couple out the interference signal output by the test generator in the interference transmission unit of the immunity test and the common mode interference signal generated when the device under test is working, and send them to the high-pass filtering unit;

[0009] The high-pass filter unit is used to filter out the low-frequency common mode signal of the normal operation of the device under test, retain the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields, and send the filtered signal to the trigger circuit unit;

[0010] The trigger circuit unit is used to compare the maximum amplitude of the filtered signal with the set threshold value. If the maximum amplitude of the signal is higher than the set threshold value, a trigger signal is generated and sent to the early warning unit;

[0011] The early warning unit is used to give an alarm when receiving a trigger signal, indicating that there is an interference signal output.

[0012] As a further improvement of the above technical solution:

[0013] The signal coupling unit includes at least one voltage probe or at least one current probe. The voltage probe is connected in parallel between the cable end to which interference is applied and the reference ground end, so that the voltage probe couples all electrical signals to the ground on the cable to which interference is applied; the current probe is stuck on the cable to which interference is applied, so that the current probe couples all common-mode current signals on the cable.

[0014] The early warning unit includes an LED lamp.

[0015] The trigger signal is a narrow pulse trigger signal.

[0016] The present invention also discloses a monitoring method based on the interference waveform output state monitoring system as described above, comprising the steps of:

[0017] The signal coupling unit couples out all the interference signals output by the test generator in the interference transmission unit of the immunity test and the common-mode interference signals generated when the device under test is working, and sends them to the high-pass filtering unit;

[0018] The high-pass filter unit filters out the low-frequency common mode signal of the normal operation of the device under test, retains the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields, and sends the filtered signal to the trigger circuit unit;

[0019] The trigger circuit unit compares the maximum amplitude of the filtered signal with the set threshold value. If the maximum amplitude of the signal is higher than the set threshold value, a trigger signal is generated and sent to the early warning unit.

[0020] The early warning unit will give an alarm upon receiving the trigger signal, indicating that there is an interference signal output.

[0021] As a further improvement of the above technical solution:

[0022] Also included is a method for determining whether the test generator has interference output.

[0023] The steps for determining whether the test generator has interference output are as follows:

[0024] 1) Before the test, only turn on the power of the device under test and set a smaller threshold to put the warning unit into the warning state;

[0025] 2) Slowly increase the set threshold value to switch the warning unit from the warning state to the non-warning state;

[0026] 3) Turn on the test generator for testing; if the warning unit switches from the non-warning state to the warning state, it indicates that the test generator has interference output; conversely, if the warning unit remains in the non-warning state, it indicates that the test generator has no interference output.

[0027] When the warning unit is in the warning state, the corresponding LED light is on; when the warning unit is in the non-warning state, the corresponding LED light is off.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] The interference waveform output state monitoring system of the present invention detects whether the power supply end immunity test generator has interference output during the test process through the cooperation between the signal coupling unit, the high-pass filtering unit, the trigger circuit unit and the early warning unit. It can quickly confirm the actual problem of whether immunity test generators of different manufacturers and models have interference output, which brings convenience to inspection engineers, makes up for the fact that most immunity test generators do not have the built-in interference waveform detection function, and also improves the test efficiency; at the same time, the overall structure is simple, easy to carry and easy to install. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the system of the present invention in an embodiment.

[0031] Figure 2 It is a diagram of an embodiment of the system of the present invention in a specific application.

[0032] Figure 3 FIG. 4 is a circuit diagram of a signal coupling unit in an embodiment of the present invention.

[0033] Figure 4 The present invention is a flowchart of an embodiment of the method.

[0034] The numbers in the figure indicate: 1. signal coupling unit; 2. high-pass filtering unit; 3. trigger circuit unit; 4. early warning unit. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0036] like Figure 1 and Figure 2 As shown, the interference waveform output state monitoring system of this embodiment includes a signal coupling unit 1, a high-pass filtering unit 2, a trigger circuit unit 3 and an early warning unit 4 connected in sequence;

[0037] The signal coupling unit 1 is used to couple out the interference signal output by the test generator in the interference transmission unit of the immunity test and the common mode interference signal generated when the device under test is working, and send them to the high-pass filtering unit 2;

[0038] The high-pass filter unit 2 is used to filter out the low-frequency common-mode voltage signal of the normal operation of the device under test, retain the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields, and send the filtered signal to the trigger circuit unit 3;

[0039] The trigger circuit unit 3 is used to compare the maximum amplitude of the filtered signal with the set threshold. If the maximum amplitude of the signal is higher than the set threshold, a trigger signal is generated and sent to the early warning unit 4.

[0040] The early warning unit 4 is used to give an alarm when receiving a trigger signal, indicating that there is an interference signal output.

[0041] The interference waveform output state monitoring system of the present invention detects whether the power supply end immunity test generator has interference output during the test process through the cooperation between the signal coupling unit 1, the high-pass filtering unit 2, the trigger circuit unit 3 and the early warning unit 4. It can quickly confirm the actual problem of whether the immunity test generators of different manufacturers and models have interference output, which brings convenience to the inspection engineers, makes up for the fact that most immunity test generators do not have the built-in interference waveform detection function, and also improves the test efficiency; at the same time, the overall structure is simple, easy to carry and easy to install.

[0042] In this embodiment, the signal coupling unit 1 is similar to the principle of measuring voltage using an oscilloscope in conjunction with a low-voltage passive probe. Figure 3 As shown in the figure. One end of the probe is connected to the power line to which interference is to be applied, and the other end is connected to the reference ground. The probe consists of an adjustable compensation capacitor Ccomp , R probe Its parasitic capacitance C probe Therefore, the signal coupling unit 1 can couple out the common mode voltage signal at the input end at a ratio of (a+b):b. The probe is connected in parallel to the cable end to which interference is applied and the reference ground end, so that it couples all electrical signals to the ground on the cable to which interference is applied; a high-resistance circuit is used to prevent shunting, and the terminal voltage signal measured by the probe is sent to the high-pass filter unit 2.

[0043] In this embodiment, the high-pass filter unit 2 includes a filter system that allows high-frequency signals to pass easily but blocks low-frequency signals from passing through. The high-pass filter unit 2 needs to be designed according to the characteristics of the immunity test waveform.

[0044] In this embodiment, the trigger circuit unit 3 generates a low-level narrow pulse trigger signal under specific circumstances, sets a threshold with adjustable amplitude, and compares the maximum amplitude of the signal in the high-pass filter unit 2 with the set threshold. If the maximum amplitude of the signal is higher than the threshold, a narrow pulse trigger signal is generated; if the signal amplitudes are all lower than the set threshold, no narrow pulse trigger signal is generated.

[0045] In this embodiment, the early warning unit 4 includes an LED light. The LED early warning unit 4 is used to prompt and visually judge the final result of whether the immunity test generator has interference output. If the trigger circuit unit 3 generates a narrow pulse trigger signal, the LED early warning unit 4 is turned on, and the LED flashes for a period of time, indicating that the test generator of the immunity test interference transmission unit has interference output; on the contrary, if the trigger circuit unit 3 does not generate a narrow pulse trigger signal, the LED early warning unit 4 is disconnected and the LED is not lit, indicating that the test generator of the immunity test interference transmission unit has no interference output. When there is no interference output, check the state of the test generator.

[0046] The present invention also discloses a monitoring method based on the interference waveform output state monitoring system as described above, comprising the steps of:

[0047] The signal coupling unit 1 couples out all the interference signals output by the test generator in the interference transmission unit of the immunity test and the common-mode interference signals generated when the device under test (EUT) is working, and sends them to the high-pass filtering unit 2;

[0048] The high-pass filter unit 2 filters out the low-frequency common-mode signal of the normal operation of the device under test, retains the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields, and sends the filtered signal to the trigger circuit unit 3;

[0049] The trigger circuit unit 3 compares the maximum amplitude of the filtered signal with the set threshold. If the maximum amplitude of the signal is higher than the set threshold, a trigger signal is generated and sent to the early warning unit 4.

[0050] The early warning unit 4 issues an alarm upon receiving a trigger signal, indicating that there is an interference signal output.

[0051] In this embodiment, a method for determining whether the test generator has interference output is also included, specifically:

[0052] 1) Before the test, only the power supply of the device under test is turned on, and a smaller threshold is set to put the early warning unit 4 into the early warning state;

[0053] 2) Slowly increase the set threshold value to switch the warning unit 4 from the warning state to the non-warning state;

[0054] 3) Turn on the test generator to conduct a test; if the warning unit 4 switches from a non-warning state to a warning state, it indicates that the test generator has an interference output; conversely, if the warning unit 4 remains in a non-warning state, it indicates that the test generator has no interference output.

[0055] In this embodiment, when the warning unit 4 is in the warning state, the corresponding LED light is on; when the warning unit 4 is in the non-warning state, the corresponding LED light is off.

[0056] Taking the conducted disturbance immunity test induced by radio frequency field as an example, the arrangement of the test generator for detecting whether there is interference output in the present invention is as follows: Figure 2 As shown (where the monitoring system connects L and PE):

[0057] In order to detect and judge the interference output of the immunity test generator, it is necessary to adjust the threshold so that the technicians can accurately judge whether the test generator has interference output. The flow chart of judging whether the test generator has interference output is as follows: Figure 4 shown.

[0058] Combine the following Figure 2 and Figure 4 Further explanation of the above method:

[0059] (1) Before the test, only turn on the power of the EUT and set a smaller threshold value so that the LED light is on;

[0060] (2) Adjust the threshold value and slowly increase it to change the LED light from on to off;

[0061] (3) Turn on the test generator for testing. If the LED changes from off to on, it indicates that the test generator has interference output. On the contrary, if the LED remains off, it indicates that the test generator has no interference output. At this time, the status of the test generator should be checked.

[0062] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. An interference waveform output state monitoring system, characterized in that: It comprises a signal coupling unit (1), a high-pass filtering unit (2), a trigger circuit unit (3) and an early warning unit (4) which are connected in sequence; The signal coupling unit (1) is used to couple out the interference signal output by the test generator in the interference transmission unit of the immunity test and the common mode interference signal generated when the device under test is working, and send them to the high-pass filtering unit (2); The high-pass filter unit (2) is used to filter out the low-frequency common mode signal of the normal operation of the device under test, retain the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields, and send the filtered signal to the trigger circuit unit (3); The trigger circuit unit (3) is used to compare the maximum amplitude of the filtered signal with a set threshold value, and if the maximum amplitude of the signal is higher than the set threshold value, a trigger signal is generated and sent to the early warning unit (4); The early warning unit (4) is used to give an alarm when receiving a trigger signal, indicating that an interference signal is output.

2. The interference waveform output state monitoring system according to claim 1, characterized in that: The signal coupling unit (1) comprises at least one voltage probe or at least one current probe, wherein the voltage probe is connected in parallel between the end of the cable to which interference is applied and the reference ground end, so that the voltage probe couples all electrical signals on the cable to which interference is applied to the ground; The current probe is clamped on the cable to which interference is applied, so that the current probe couples all common mode current signals on the cable.

3. The interference waveform output state monitoring system according to claim 1 or 2, characterized in that: The early warning unit (4) comprises an LED lamp.

4. The interference waveform output state monitoring system according to claim 1 or 2, characterized in that: The trigger signal is a narrow pulse trigger signal.

5. A monitoring method based on the interference waveform output state monitoring system according to any one of claims 1 to 4, characterized in that: Includes steps: The signal coupling unit (1) couples out all the interference signals output by the test generator in the interference transmission unit of the immunity test and the common-mode interference signals generated when the device under test is working, and sends them to the high-pass filtering unit (2); The high-pass filter unit (2) filters out the low-frequency common mode signal of the normal operation of the device under test, retains the signal components with higher frequency and high frequency characteristics in the conducted disturbance waveform induced by electrical fast transient pulse groups, surges and radio frequency fields, and sends the filtered signal to the trigger circuit unit (3); The trigger circuit unit (3) compares the maximum amplitude of the filtered signal with a set threshold value, and if the maximum amplitude of the signal is higher than the set threshold value, a trigger signal is generated and sent to the early warning unit (4); The early warning unit (4) issues an alarm upon receiving a trigger signal, indicating that an interference signal is output.

6. The monitoring method according to claim 5, characterized in that: Also included is a method for determining whether the test generator has interference output.

7. The monitoring method according to claim 6, characterized in that: The steps for determining whether the test generator has interference output are as follows: 1) Before the test, only the power supply of the device under test is turned on, and a relatively small threshold is set to put the early warning unit (4) into an early warning state; 2) slowly increasing the set threshold value so that the warning unit (4) switches from the warning state to the non-warning state; 3) Turn on the test generator to conduct a test; if the warning unit (4) switches from a non-warning state to a warning state, it indicates that the test generator has an interference output; conversely, if the warning unit (4) remains in a non-warning state, it indicates that the test generator has no interference output.

8. The monitoring method according to claim 7, characterized in that: When the warning unit (4) is in the warning state, the corresponding LED light is on; when the warning unit (4) is in the non-warning state, the corresponding LED light is off.

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