A conducted emission test system verification device and method

Abstract

The present invention relates to the technical field of electromagnetic compatibility testing, and discloses a device and method for verifying a conducted emission test system, the device comprising a darkroom, a positive LISN, a negative LISN, a radio frequency signal generator, and a receiver arranged outside the darkroom, the positive LISN, the negative LISN, and the radio frequency signal generator are all arranged inside the darkroom, and the radio frequency signal generator is connected to the receiver through the positive LISN and the negative LISN, respectively. The present invention generates a radio frequency signal of given strength and step length by using a standard radio frequency signal generator to replace a sample under test to access a test system for data measurement, which not only eliminates the influencing factors of a vehicle battery and a sample under test, but also because the stability of the standard radio frequency signal generator is higher than that of the sample under test, and it can be directly connected to an oscilloscope for status detection at any time, so that it can directly determine whether it is a problem with the sample under test or a problem with the test system, and can quantify the influence of the background noise problem on the test result, which is convenient and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic compatibility testing, and in particular to a device and method for verifying a conducted emission testing system. Background Art

[0002] As new energy vehicles develop towards intelligence and electrification, the number of electronic and electrical parts installed in vehicles is gradually increasing. However, the circuits of different parts will intersect with the same battery or the same controller in the vehicle. When passing through these intersections, the signals of different parts may be transmitted along the wires to the circuits of other parts, causing interference to other parts in the vehicle. Therefore, in order to limit the intensity of interference emitted by different parts, the state has issued standards to conduct conducted emission tests on parts.

[0003] When conducting emission tests, the test data and the test system (LISN and receiver) noise floor are often close. In order to confirm whether the problem is with the test system itself or with the state of the DUT 100, the current industry practice is to keep the DUT 100 connected to the test system but not to power the DUT 100, so that the DUT 100 is in a non-working state, as follows: Figure 1 As shown, if the test curve is very low, it is considered that there is no problem with the test system noise floor. However, this solution is very susceptible to other factors, such as low power of the vehicle battery 400, poor connection between the LISN and the receiver 500, LISN or receiver 500 failure, etc., which will cause the test data to be close to the noise floor. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a conducted emission test system verification device and method, which eliminates the influencing factors of the vehicle-mounted battery and the sample under test, ensures the accuracy of the conducted emission test system verification, and further can directly determine whether the problem is the sample under test or the test system.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A conducted emission test system verification device comprises a darkroom, a positive LISN, a negative LISN, a radio frequency signal generator and a receiver arranged outside the darkroom, wherein the positive LISN, the negative LISN and the radio frequency signal generator are all arranged inside the darkroom, and the radio frequency signal generator is connected to the receiver via the positive LISN and the negative LISN respectively.

[0007] A method for verifying a conducted emission test system comprises the following steps:

[0008] Step 1: Connect the RF signal generator to an oscilloscope to record the amplitude and frequency of the initial waveform;

[0009] Step 2: Connect the RF signal generator to the receiver through the positive LISN and the negative LISN respectively;

[0010] Step 3, start the receiver for testing and record the amplitude of the RF signal generator;

[0011] Step 4: After the receiver test is completed, the RF signal transmitter is connected to the oscilloscope again, the amplitude and frequency of the waveform at this time are recorded, and compared with the amplitude and frequency of the initial waveform in step 1 to ensure that the RF signal transmitter works properly;

[0012] Step 5, repeat steps 2 and 3 for multiple times, and record the amplitude of each waveform through the receiver;

[0013] Step 6, comparing each amplitude in step 5 with the set parameters of the RF signal generator, and taking the mean square error σ between multiple amplitude data and the set parameter value;

[0014] Step seven, compare σ with the threshold. If it is greater than the threshold, it can be determined as a problem with the conducted emission system; if it is less than or equal to the threshold, it can be determined as a problem with the test sample.

[0015] Preferably, in step 1, the RF signal generator needs to be fully charged first, and then adjusted to a step size of 1 MHz and a signal strength of -60 db.

[0016] Preferably, in step 4, if the deviation between the amplitude and frequency of the waveform recorded in step 4 and the amplitude and frequency of the initial waveform recorded in step 1 is less than or equal to 5%, it is determined that the RF signal transmitter is working normally; if the deviation is greater than 5%, it is determined that the RF signal transmitter is working abnormally, and the RF signal generator needs to be replaced and retested.

[0017] Preferably, the amplitude and frequency deviations of the waveform recorded in step 4 and the amplitude and frequency deviations of the initial waveform recorded in step 1 include an amplitude deviation ε1 and a frequency deviation ε2, wherein both ε1 and ε2 are less than or equal to 5%, then it is determined that the RF signal transmitter is operating normally; if either of ε1 and ε2 is greater than 5%, then it is determined that the RF signal transmitter is operating abnormally.

[0018] Preferably, the amplitude and frequency of the waveform recorded by the oscilloscope in step 1 are A0 and f0 respectively, and the amplitude and frequency of the waveform recorded by the oscilloscope in step 4 are A1 and f1 respectively, then:

[0019] ε1=(A1-A0) / A0·100%;

[0020] ε2=(f1-f0) / f0·100%.

[0021] Preferably, in step 6, the number of cycles is m, and the amplitude recorded by the receiver for the nth time is B n , n≤m;

[0022]

[0023] Preferably, in step seven, the threshold is 6db.

[0024] Preferably, in step five, step four needs to be repeated to ensure that the radio frequency signal transmitter operates normally each time the receiver records the amplitude.

[0025] Compared with the prior art, a conducted emission test system verification device and method according to an embodiment of the present invention has the following beneficial effects: by using a standard RF signal generator to generate an RF signal of given strength and step length, instead of connecting the test sample to the test system for data measurement, not only the influencing factors of the vehicle battery and the test sample are eliminated, but also because the stability of the standard RF signal generator is higher than that of the test sample, and the oscilloscope can be directly connected to perform status detection at any time, it is possible to directly determine whether it is a problem with the test sample or the test system, and the influence of the background noise problem on the test results can be quantified, which is convenient and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the existing conducted emission system verification method.

[0027] Figure 2 It is a structural schematic diagram of the conducted emission test system verification device of the present invention.

[0028] Among them: 1-darkroom, 2-positive LISN, 3-negative LISN, 4-RF signal generator, 5-receiver;

[0029] 100-test sample, 200-positive LISN, 300-negative LISN, 400-vehicle battery, 500-receiver. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] like Figure 2 As shown, a conducted emission test system verification device according to a preferred embodiment of the present invention comprises a darkroom 1, a positive LISN 2, a negative LISN 3, a radio frequency signal generator 4 and a receiver 5 arranged outside the darkroom 1, wherein the positive LISN 2, the negative LISN 3 and the radio frequency signal generator 4 are all arranged inside the darkroom 1, and the radio frequency signal generator 4 is connected to the receiver 5 through the positive LISN 2 and the negative LISN 3, respectively.

[0033] The conducted emission test system verification device based on the above technical features uses a standard RF signal generator 4 to generate an RF signal of a given strength and step length, and replaces the sample under test to connect to the test system for data measurement. This not only eliminates the influence of the vehicle battery and the sample under test, but also because the stability of the standard RF signal generator 4 is higher than that of the sample under test, and the oscilloscope can be directly connected to the status detection at any time, it can directly determine whether it is a problem with the sample under test or the test system, and can quantify the influence of the background noise problem on the test results, which is convenient and reliable.

[0034] In order to solve the above technical problems, the present application also provides a method for verification using the above conducted emission test system verification device, comprising the following steps:

[0035] Step 1: First, fully charge the RF signal generator 4, then adjust it to a step size of 1 MHz and a signal strength of -60 db, then connect the RF signal generator 4 to an oscilloscope, and record the amplitude A0 and frequency f0 of the initial waveform through the oscilloscope.

[0036] Step 2: Connect the RF signal generator 4 to the receiver via the positive LISN2 and the negative LISN3 respectively.

[0037] Step three, start the receiver 5 to perform a test, and record the amplitude of the RF signal generator 4.

[0038] Step 4: After the receiver 5 test is completed, the RF signal transmitter 4 is connected to the oscilloscope again, and the amplitude A1 and frequency f1 of the waveform at this time are recorded and compared with the amplitude and frequency of the initial waveform in step 1 to ensure that the RF signal transmitter 4 works properly.

[0039] Specifically, the amplitude and frequency of the waveform recorded in step 4 and the amplitude and frequency deviation of the initial waveform recorded in step 1 include amplitude deviation ε1 and frequency deviation ε2, where ε1 and ε2 are both less than or equal to 5%, then it is determined that the RF signal transmitter 4 is working normally; if any one of ε1 and ε2 is greater than 5%, then it is determined that the RF signal transmitter 4 is working abnormally. Wherein:

[0040] ε1=(A1-A0) / A0·100%;

[0041] ε2=(f1-f0) / f0·100%.

[0042] Step 5, repeat steps 2 and 3, and cycle for multiple times, and record the amplitude of the waveform each time through the receiver 5.

[0043] In addition, since multiple measurements need to be performed in a cycle, in order to ensure that the RF signal transmitter 4 works normally when the receiver 5 records the amplitude during each measurement, and there is no power outage or damage, in step five, step four needs to be repeated to ensure that the RF signal transmitter 4 works normally to ensure the accuracy of subsequent measurements.

[0044] Step 6: Compare each amplitude in step 5 with the set parameter of the RF signal generator 4 (such as -60db in the present application), and obtain the mean square error σ between multiple amplitude data and the set parameter value.

[0045] Step seven, compare σ with the threshold. If it is greater than the threshold, it can be determined as a problem with the conducted emission system; if it is less than or equal to the threshold, it can be determined as a problem with the test sample.

[0046] Among them, the threshold is 6db;

[0047] In step 6, the number of cycles is m, and the amplitude recorded by the receiver for the nth time is B n , n≤m, then:

[0048]

[0049] Taking the example of three cycles, If the calculated σ>6db, it can be judged as a problem with the conducted emission system; if σ≤6db, it can be judged as a problem with the test sample.

[0050] In summary, the present application uses a standard RF signal generator 4 to replace the sample under test, which expands the testable frequency band and ensures signal stability, making the result more reliable; at the same time, the mean square error value is introduced for calculation, which reduces the randomness and instability of the data and ensures the accuracy of the verification.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A conducted emission test system verification device, characterized in that: The invention comprises a darkroom, a positive LISN, a negative LISN, a radio frequency signal generator and a receiver arranged outside the darkroom. The positive LISN, the negative LISN and the radio frequency signal generator are all arranged inside the darkroom, and the radio frequency signal generator is connected to the receiver through the positive LISN and the negative LISN respectively.

2. A method for verifying a conducted emission test system, characterized in that: The following steps are involved: Step 1: Connect the RF signal generator to an oscilloscope to record the amplitude and frequency of the initial waveform; Step 2: Connect the RF signal generator to the receiver through the positive LISN and the negative LISN respectively; Step 3, start the receiver for testing and record the amplitude of the RF signal generator; Step 4: After the receiver test is completed, the RF signal transmitter is connected to the oscilloscope again, the amplitude and frequency of the waveform at this time are recorded, and compared with the amplitude and frequency of the initial waveform in step 1 to ensure that the RF signal transmitter works properly; Step 5, repeat steps 2 and 3 for multiple times, and record the amplitude of each waveform through the receiver; Step 6, comparing each amplitude in step 5 with the set parameters of the RF signal generator, and taking the mean square error σ between multiple amplitude data and the set parameter value; Step seven, compare σ with the threshold. If it is greater than the threshold, it can be determined as a problem with the conducted emission system; if it is less than or equal to the threshold, it can be determined as a problem with the test sample.

3. The conducted emission test system verification method as claimed in claim 2, characterized in that: In step 1, the RF signal generator must be fully charged first, and then adjusted to a step size of 1 MHz and a signal strength of -60 db.

4. The conducted emission test system verification method according to claim 2, characterized in that: In step 4, if the amplitude and frequency of the waveform recorded in step 4 deviate from the amplitude and frequency of the initial waveform recorded in step 1 by less than or equal to 5%, it is determined that the radio frequency signal transmitter is operating normally; If the deviation is greater than 5%, it is determined that the RF signal transmitter is working abnormally, and the RF signal generator needs to be replaced and retested.

5. The conducted emission test system verification method as claimed in claim 4, characterized in that: The amplitude and frequency deviations of the waveform recorded in step 4 and the amplitude and frequency deviations of the initial waveform recorded in step 1 include an amplitude deviation ε1 and a frequency deviation ε2, wherein both ε1 and ε2 are less than or equal to 5%, then it is determined that the radio frequency signal transmitter is working properly; If either ε1 or ε2 is greater than 5%, it is determined that the radio frequency signal transmitter is operating abnormally.

6. The conducted emission test system verification method as claimed in claim 5, characterized in that: The amplitude and frequency of the waveform recorded by the oscilloscope in step 1 are A0 and f0 respectively, and the amplitude and frequency of the waveform recorded by the oscilloscope in step 4 are A1 and f1 respectively, then: ε1=(A1-A0) / A0·100%; ε2=(f1-f0) / f0·100%.

7. The conducted emission test system verification method according to claim 6, characterized in that: In step 6, the number of cycles is m, and the amplitude recorded by the receiver for the nth time is B n , n≤m; 8. The conducted emission test system verification method according to claim 7, characterized in that: In step seven, the threshold is 6db.

9. The conducted emission test system verification method according to any one of claims 2 to 8, characterized in that: In the step five, step four needs to be repeated to ensure that the radio frequency signal transmitter operates normally each time the receiver records the amplitude.

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