CN117214543A - Online measurement circuit and method for differential mode insertion loss of EMI filter - Google Patents
Online measurement circuit and method for differential mode insertion loss of EMI filter Download PDFInfo
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- CN117214543A CN117214543A CN202311124460.0A CN202311124460A CN117214543A CN 117214543 A CN117214543 A CN 117214543A CN 202311124460 A CN202311124460 A CN 202311124460A CN 117214543 A CN117214543 A CN 117214543A
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- 238000012360 testing method Methods 0.000 claims abstract description 113
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Abstract
The application discloses an online measurement circuit and a test method for differential mode insertion loss of an EM I filter, and relates to the technical field of EM I filter measurement. The method specifically comprises the following steps: a power circuit with an EM I filter; a first test circuit for outputting a test signal to an EM I filter in the power circuit; and a second test circuit for receiving the test signal through the EM I filter. The method aims to realize online measurement of the differential mode insertion loss of the EM I filter, improve the test precision and reduce the test cost.
Description
Technical Field
The application relates to the technical field of measurement of an EMI filter, in particular to an online measurement circuit and a test method for the differential mode insertion loss of the EMI filter.
Background
An EMI filter is an electronic component for suppressing electromagnetic interference and noise, and is generally connected in a power or signal line of a device. In practical applications, the performance of an EMI filter needs to be tested to evaluate its filtering effect and stability. The differential mode insertion loss is an important parameter in the performance test of the EMI filter, and is used for balancing the attenuation degree of the differential mode signal during the transmission process in the EMI filter.
Since the conventional differential insertion loss test method requires taking out the EMI filter after the power of the apparatus to test it separately, it takes time and labor to remove and reinstall the EMI filter, and especially in the production or field test, if a large number of EMI filters are to be tested, the test time and cost are increased. Meanwhile, in the process of removing the EMI filter, damage may be generated to the EMI filter itself, or other interference factors may be introduced, resulting in inaccurate test results.
Therefore, how to realize online measurement of the differential mode insertion loss of the EMI filter becomes a technical problem to be solved.
Disclosure of Invention
The application mainly aims to provide an on-line measuring circuit and a testing method for the differential mode insertion loss of an EMI filter, and aims to realize on-line measurement of the differential mode insertion loss of the EMI filter, improve the testing precision and reduce the testing cost.
In order to achieve the above object, the present application provides an EMI filter differential mode insertion loss on-line measurement circuit, comprising:
a power circuit with an EMI filter;
a first test circuit for outputting a test signal to an EMI filter in the power circuit; and
a second test circuit for receiving the test signal through the EMI filter.
In one embodiment of the present application, the first test circuit includes:
the signal generator is connected with the power supply anode of the EMI filter through the first capacitor at the first end and connected with the grounding electrode of the EMI filter through the second capacitor at the second end.
In one embodiment of the application, the first test circuit further comprises a first resistor disposed between the first end of the signal generator and the positive power supply of the EMI filter.
In one embodiment of the present application, the second test circuit includes:
and the second end of the receiver is connected with the load grounding electrode of the EMI filter through a fourth capacitor.
In one embodiment of the application, the second test circuit further comprises a second resistor disposed between the first end of the receiver and the load anode of the EMI filter.
The application also discloses a test method of the EMI filter differential mode insertion loss on-line measurement circuit, which comprises the following steps:
setting a test frequency point and corresponding voltage parameters of a first test circuit, and sending an initial test signal to an EMI filter;
and obtaining a decayed test signal passing through the EMI filter through a second test circuit, and obtaining a differential mode insertion loss corresponding to a test rate point of the first test circuit according to the initial test signal and the decayed test signal.
In one embodiment of the present application, the initial test signal is defined as U i The decaying test signal is U o The differential mode insertion loss is referred to as IL,
by adopting the technical scheme, the differential mode insertion loss of the EMI filter in the power circuit can be measured on line, the EMI filter does not need to be independently taken down for testing, the testing cost and time can be reduced, and the testing efficiency is improved. Meanwhile, the test circuit can be more close to an actual application scene, and can reflect the performance and stability of the EMI filter in actual work.
Drawings
The application will now be described in detail with reference to specific embodiments and accompanying drawings, in which:
FIG. 1 is a schematic diagram of a first embodiment of the present application;
10. a filter; 20. a signal generator; 30. a signal receiver; 40. a power supply, 50, a load.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described in detail with reference to the accompanying drawings and examples. It should be understood that the following specific examples are given by way of illustration only and are not intended to be limiting.
As shown in fig. 1, in order to achieve the above object, the present application proposes an EMI filter 10 differential mode insertion loss on-line measurement circuit, comprising:
a power circuit with EMI (Electromagnetic Interference) filter 10;
a first test circuit for outputting a test signal to the EMI filter 10 in the power circuit; and
a second test circuit for receiving test signals through EMI filter 10.
Specifically, the power circuit with the EMI filter 10 includes a power supply 40, the EMI filter 10, and a load 50. The positive electrode of the power supply 40 is connected to the positive electrode vin+ of the power supply of the EMI filter 10, the negative electrode of the power supply 40 is connected to the circuit of the ground electrode VIN of the EMI filter 10, the positive electrode of the load 50 is connected to the positive electrode vo+ of the load of the EMI filter 10, and the negative electrode of the load 50 is connected to the circuit of the load ground electrode VO of the EMI filter 10. The EMI filter 10 is used to suppress electromagnetic interference and noise.
The first test circuit is for outputting a test signal to the EMI filter 10 in the power circuit. Specifically, the device comprises a signal source, a control circuit and the like. The signal source can generate a differential mode signal with certain amplitude and frequency, and the control circuit can control the output of the signal source so as to test, wherein the test signal is a set value, and the specific numerical parameters are known, and comprise a frequency point and a voltage signal corresponding to the frequency point.
The second test circuit is used to receive the test signal that has passed through the EMI filter 10 and to perform measurements and analyses. The second test circuit is used to receive test signals from the EMI filter 10 in the power circuit.
By adopting the technical scheme, the on-line measurement of the differential mode insertion loss of the EMI filter 10 in the power circuit can be realized, the EMI filter 10 does not need to be independently taken down for testing, the testing cost and time can be reduced, and the testing efficiency is improved. Meanwhile, the test circuit can be more close to an actual application scene, and can reflect the performance and stability of the EMI filter 10 in actual operation.
In one embodiment of the present application, the first test circuit includes:
the signal generator 20 has a first terminal connected to the positive electrode of the power supply 40 of the EMI filter 10 through the first capacitor C1, and a second terminal connected to the ground electrode of the EMI filter 10 through the second capacitor C2.
Specifically, the signal generator 20 is configured to generate a test signal, typically a differential mode signal of a certain amplitude and frequency. The signal generator 20 may be any type of signal source, such as a function generator, signal generator 20, signal analyzer, etc.
The first capacitor C1 is used to couple the output signal of the signal generator 20 to the positive electrode of the power supply 40 of the EMI filter 10. The first capacitor C1 is typically a high frequency capacitor for transmitting the differential mode signal of the signal generator 20 into the EMI filter 10 while blocking the direct current and low frequency signals.
The second capacitor C2 is used to connect the ground electrode of the EMI filter 10 with the ground, so as to ensure the accuracy and stability of the test. The second capacitor C2 is typically a high frequency capacitor that blocks low frequency and dc signals while connecting the ground of the EMI filter 10 to the test ground.
With the above technical solution, the first terminal of the signal generator 20 is connected to the positive electrode of the power supply 40 of the EMI filter 10 through the first capacitor C1, for injecting the test signal into the EMI filter 10. A second terminal of the signal generator 20 is connected to the ground of the EMI filter 10 through a second capacitor C2 for connecting the ground of the EMI filter 10 to the test ground to ensure the accuracy and stability of the test. The negative and ground poles of the power supply 40 and the ground of the EMI filter 10 are connected to the power supply 40 and the ground, respectively, to ensure proper operation of the EMI filter 10. By adopting the connection mode, the differential mode signal of the signal generator 20 can be injected into the EMI filter 10, and meanwhile, the low-frequency and direct-current signals are blocked, so that the accuracy and the stability of the test are ensured. In addition, the connection of the second capacitor C2 can also prevent interference signals and noise in the test process, and the reliability of the test result is improved.
In one embodiment of the present application, the first test circuit further includes a first resistor R1 disposed between the first terminal of the signal generator 20 and the positive power supply of the EMI filter 10.
Specifically, the first resistor R1 is provided to limit the current of the test signal, prevent the test signal from having an excessive influence on the EMI filter 10, and protect the signal generator 20.
In one embodiment of the present application, the second test circuit includes:
the receiver has a first end connected to the load positive electrode vo+ of the EMI filter 10 through a third capacitor C3, and a second end connected to the load ground electrode VO loop of the EMI filter 10 through a fourth capacitor C4.
Specifically, the receiver is configured to receive the test signal that has passed through the EMI filter 10, and to perform measurements and analyses.
The third capacitor C3 is used to couple the input signal of the receiver to the load anode vo+ of the EMI filter 10. The third capacitor C3 is typically a high frequency capacitor for transmitting the test signal through the EMI filter 10 into the receiver while blocking both dc and low frequency signals.
The fourth capacitor C4 is used to connect the load grounding electrode VO loop of the EMI filter 10 with the test ground, so as to ensure the accuracy and stability of the test.
With the above technical solution, the first end of the receiver is connected to the load positive electrode of the EMI filter 10 through the third capacitor C3, and is used for receiving the test signal passing through the EMI filter 10. The second end of the receiver is connected to the load ground of the EMI filter 10 through the fourth capacitor C4, and is used for connecting the load ground of the EMI filter 10 with the test ground, so as to ensure the accuracy and stability of the test. The load cathode and the ground electrode of the EMI filter 10 are connected to the load 50 and the ground, respectively, to ensure proper operation of the EMI filter 10. By adopting the connection mode, the test signal passing through the EMI filter 10 can be transmitted to the receiver, and meanwhile, the low-frequency and direct-current signals are blocked, so that the accuracy and stability of the test are ensured. In addition, the connection of the fourth capacitor C4 can also prevent interference signals and noise in the test process, and the reliability of the test result is improved.
In one embodiment of the present application, the second test circuit further includes a second resistor R2 disposed between the first end of the receiver and the load anode of the EMI filter 10.
Specifically, the second resistor R2 is provided to limit the current of the test signal, prevent the test signal from having an excessive influence on the EMI filter 10, and protect the signal generator 20.
The application also discloses a testing method of the on-line measuring circuit of the differential mode insertion loss of the EMI filter 10, which comprises the following steps:
setting a test frequency point and corresponding voltage parameters of the first test circuit, and transmitting an initial test signal to the EMI filter 10;
the test signal after decay through the EMI filter 10 is obtained by the second test circuit, and the differential mode insertion loss corresponding to the test rate point of the first test electricity is obtained according to the initial test signal and the decay test signal.
Specifically, a test frequency point and a corresponding voltage parameter of the first test circuit are set. For example, the test frequency points encompass critical frequency points within the operating range of the EMI filter 10, such as the 3dB cut-off frequency, the resonant frequency, etc.
When transmitting the initial test signal, it is necessary to set the signal generator 20 to a desired test frequency point and voltage parameter, and then inject the differential mode signal into the EMI filter 10 through the first test circuit. At this time, the received signal may be detected using a test device such as an oscilloscope to ensure that the signal generator 20 and test circuitry are functioning properly.
When the attenuated test signal passing through the EMI filter 10 is acquired, the attenuated test signal is received using a second test circuit and transmitted to a receiver for measurement and analysis.
With the above-described technical scheme, the differential mode insertion loss of the EMI filter 10 can be accurately measured by this test method, thereby evaluating the performance and reliability thereof. The flow is simple and convenient to implement.
In one embodiment of the present application, the initial test signal is defined as U i The decaying test signal is U o The differential mode insertion loss is referred to as IL,
the foregoing description is only of the preferred embodiments of the present application and is not intended to limit the scope of the application, and all equivalent structural changes made by the description of the present application and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the application.
Claims (7)
1. An EMI filter differential mode insertion loss on-line measurement circuit, comprising:
a power circuit with an EMI filter;
a first test circuit for outputting a test signal to an EMI filter in the power circuit; and
a second test circuit for receiving the test signal through the EMI filter.
2. The EMI filter differential mode insertion loss on-line measurement circuit of claim 1, wherein the first test circuit comprises:
the signal generator is connected with the power supply anode of the EMI filter through the first capacitor at the first end and connected with the grounding electrode of the EMI filter through the second capacitor at the second end.
3. The EMI filter differential mode insertion loss on-line measurement circuit of claim 2 wherein,
the first test circuit further includes a first resistor disposed between the first end of the signal generator and the positive power supply of the EMI filter.
4. The EMI filter differential mode insertion loss on-line measurement circuit of claim 1, wherein,
the second test circuit includes:
and the second end of the receiver is connected with the load grounding electrode of the EMI filter through a fourth capacitor.
5. The EMI filter differential mode insertion loss on-line measurement circuit of claim 4, wherein,
the second test circuit further includes a second resistor disposed between the first end of the receiver and the load anode of the EMI filter.
6. The test method of the online measurement circuit of the differential mode insertion loss of the EMI filter is characterized by comprising the following steps:
setting a test frequency point and corresponding voltage parameters of a first test circuit, and sending an initial test signal to an EMI filter;
and obtaining a decayed test signal passing through the EMI filter through a second test circuit, and obtaining a differential mode insertion loss corresponding to a test rate point of the first test circuit according to the initial test signal and the decayed test signal.
7. The method for testing an EMI filter differential mode insertion loss on-line measurement circuit of claim 6, wherein the initial test signal is defined as U i The decaying test signal is U o The differential mode insertion loss is referred to as IL,
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311124460.0A CN117214543A (en) | 2023-08-31 | 2023-08-31 | Online measurement circuit and method for differential mode insertion loss of EMI filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311124460.0A CN117214543A (en) | 2023-08-31 | 2023-08-31 | Online measurement circuit and method for differential mode insertion loss of EMI filter |
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| Publication Number | Publication Date |
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| CN117214543A true CN117214543A (en) | 2023-12-12 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202311124460.0A Pending CN117214543A (en) | 2023-08-31 | 2023-08-31 | Online measurement circuit and method for differential mode insertion loss of EMI filter |
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| CN (1) | CN117214543A (en) |
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- 2023-08-31 CN CN202311124460.0A patent/CN117214543A/en active Pending
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