Method for testing shielding attenuation and transfer impedance of high-voltage cable in vehicle

Abstract

The invention discloses a method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle, and the method comprises the steps: preparing equipment, preparing a testing environment, carrying out a transfer impedance test, carrying out a shielding attenuation test, analyzing and recording data, and carrying out the cleaning and arrangement after the test. Therefore, the test process is simpler, more convenient and quicker, current signals under different frequencies can be accurately measured, the shielding attenuation performance of the high-voltage cable under different frequencies can be comprehensively evaluated, the current probe covering various frequency signals has higher sensitivity, weak current signals in the high-voltage cable can be detected, and the shielding attenuation performance of the high-voltage cable under different frequencies can be comprehensively evaluated. Potential problems are found in time, corresponding measures are taken for improvement, the shielding attenuation effect of the high-voltage cable is evaluated more accurately, compatibility with other equipment is good, technicians can observe, analyze and record measurement results conveniently, and the device is suitable for various testing environments.

Description

Technical Field

[0001] The invention relates to the technical field of automotive electronic and electrical system testing, and in particular to a method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle. Background Art

[0002] In new energy vehicles, there are a large number of electronic devices in the car, such as battery management system (BMS), motor controller, on-board charger, etc. These devices will generate electromagnetic signals of various frequencies when working, and are also susceptible to external electromagnetic interference. As a key component of power transmission, if the high-voltage cable in the car does not have good shielding and attenuation performance, external interference signals may be coupled into the high-voltage cable.

[0003] In the prior art, the tube-in-tube method and the wire injection method are usually used to test the shielding attenuation and transfer impedance of the high-voltage cable in the vehicle. However, the test layout of the tube-in-tube method is complicated and requires the high-voltage wire harness to be passed through the shielding tube, which makes the test preparation work cumbersome and increases the test cost and time. At the same time, the wire injection method is easily affected by the external environment, resulting in inaccurate test data. It has high requirements on the test environment and needs to be tested in an environment with a stable electromagnetic environment and fewer interference sources. This is difficult to fully meet in actual test scenarios, limiting the reliability and repeatability of its test. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for testing the shielding attenuation and transfer impedance of a high-voltage cable in a vehicle, which can effectively solve the problem of the limitations of the tube-in-tube method and the line injection method in testing the shielding attenuation and transfer impedance of the high-voltage cable in the vehicle.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle, the method comprising:

[0006] Stage 1: Equipment preparation: Select a suitable current probe that meets the test requirement parameters, prepare an oscilloscope to accurately display and record the measurement results, and the current probe should be compatible with the oscilloscope to receive the signal output by the current probe.

[0007] Phase 2: Test environment preparation: The electromagnetic size of the test environment should be adjusted to avoid the influence of external electromagnetic fields on the test results, and the high-voltage cables in the vehicle should be placed stably;

[0008] Stage 3: Connecting the test equipment: Correctly clamp the current probe on the high-voltage cable in the vehicle, and use a connecting cable to connect the output end of the current probe to the input end of the oscilloscope;

[0009] Stage 4: Setting oscilloscope parameters: According to the test requirements, setting the parameters of the oscilloscope to accurately display the signal output by the current probe;

[0010] Stage 5: Perform transfer impedance test: including applying current excitation, measuring voltage signal and calculating transfer impedance;

[0011] Stage 6: Conduct shielding attenuation test: including measuring the electromagnetic field outside the shielding layer and calculating the shielding attenuation;

[0012] Phase 7, data analysis and recording: including analysis and recording, wherein the analysis is to analyze the transfer impedance and shielding attenuation data obtained from the test to determine whether the performance of the high-voltage cable in the vehicle meets the requirements, and the recording is to record the test data and parameters.

[0013] Stage 8: Cleaning and tidying up after the test: This includes cleaning and tidying up, in which the current probe is removed from the high-voltage cable in the vehicle, and the test site is cleaned up, in which the test equipment and connecting cables are properly stored.

[0014] Preferably, the test requirement parameters include but are not limited to bandwidth and measurement range, and the oscilloscope has sufficient bandwidth and sampling rate.

[0015] Preferably, the parameters of the oscilloscope include but are not limited to vertical sensitivity, horizontal scanning speed and trigger mode.

[0016] Preferably, the applied current excitation is based on a suitable current source to apply a current signal to the high-voltage cable in the vehicle, the measured voltage signal is based on a current probe measuring the current signal on the cable, and converting it into a voltage signal and outputting it to an oscilloscope, and the calculated transfer impedance is based on the measured voltage signal and the applied current signal, and according to the definition of transfer impedance, the transfer impedance of the high-voltage cable in the vehicle is calculated.

[0017] Preferably, the electromagnetic field outside the shielding layer is measured by turning off the current source and using an electromagnetic field probe to measure the electromagnetic field strength outside the shielding layer of the high-voltage cable in the vehicle. The shielding attenuation is calculated based on the measured electromagnetic field strength and the current signal inside the cable, according to the definition of shielding attenuation, to calculate the shielding attenuation of the high-voltage cable in the vehicle.

[0018] Preferably, the magnitude and frequency of the current signal should comply with the test standard, and the transfer impedance is defined as the ratio of the secondary voltage to the primary current.

[0019] Preferably, the shielding attenuation is defined as the logarithm of the ratio of the electromagnetic field strength before shielding to the electromagnetic field strength after shielding.

[0020] Preferably, the data and parameters include but are not limited to current magnitude, frequency, voltage signal, electromagnetic field strength, test time and tester.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the present invention, the method can achieve non-contact measurement without damaging the circuit. The current probe can perform measurement without cutting or disconnecting the high-voltage cable, thereby maintaining the integrity of the vehicle's electrical system, avoiding unnecessary damage or interference to the vehicle's circuit due to testing, and reducing the workload of reconnection and debugging and the risk of possible failures. Non-contact measurement makes the testing process simpler and faster. The current signal can be obtained by simply clamping the current probe on the high-voltage cable without complicated wiring operations, which greatly improves the testing efficiency. It is especially suitable for situations where the space in the vehicle is limited and the lines are complex.

[0023] 2. In the present invention, the signal frequency range of the high-voltage cable transmission in the vehicle of this method is relatively wide, including both low-frequency DC components and high-frequency AC components. The current probe has a relatively wide frequency response range and can accurately measure current signals at different frequencies, thereby comprehensively evaluating the shielding attenuation performance of the high-voltage cable at different frequencies, thereby achieving coverage of multiple frequency signals. At the same time, the current probe can quickly respond to transient signals of the vehicle during movement, accurately capture instantaneous current changes, and provide strong support for analyzing the shielding attenuation performance of the high-voltage cable under transient conditions.

[0024] 3. In the present invention, the method has high-sensitivity measurement, and the current probe has high sensitivity, which can detect weak current signals in high-voltage cables, can timely discover potential problems, and take corresponding measures to improve them. It can more accurately evaluate the shielding attenuation effect of high-voltage cables, and can detect the shielding degree of the cable shielding layer on the internal current signal, as well as the interference degree of the external electromagnetic field on the internal signal of the cable, providing accurate data basis for optimizing the shielding design of the cable.

[0025] 4. In the present invention, the method has flexible measurement position selection. The small and flexible structure of the current probe enables it to be conveniently clamped on different parts of the cable for measurement. Whether in a narrow space, a curved line or near an electronic device, the current signal can be accurately obtained, and the shielding attenuation performance of the cable at different positions can be comprehensively evaluated. When electromagnetic interference or electrical failure occurs in the vehicle, the location of the fault can be quickly located by using the current probe for measurement at different positions, helping technicians to accurately determine whether the problem is caused by damage to the cable shielding layer, loose wiring or other reasons, thereby improving the efficiency of troubleshooting and repair.

[0026] 5. In the present invention, the method has good compatibility with other equipment. The current probe can be directly connected to commonly used electronic measuring equipment such as oscilloscopes and spectrum analyzers, which is convenient for technicians to observe, analyze and record the measurement results. It is suitable for a variety of test environments. Whether in a laboratory environment or in the field environment where the vehicle is actually operating, the current probe can cooperate well with other test equipment to meet the needs of different test scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0029] A method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle, the method comprising:

[0030] Stage 1: Equipment preparation: Select a suitable current probe that meets the test requirements and prepare an oscilloscope to accurately display and record the measurement results. The current probe should be compatible with the oscilloscope to receive the signal output by the current probe.

[0031] Phase 2: Test environment preparation: The electromagnetic size of the test environment should be adjusted to avoid the influence of external electromagnetic fields on the test results, and the high-voltage cables in the vehicle should be placed stably;

[0032] Stage 3: Connect the test equipment: Correctly clamp the current probe on the high-voltage cable in the vehicle, and use the connecting cable to connect the output of the current probe to the input of the oscilloscope;

[0033] Stage 4: Set oscilloscope parameters: According to the test requirements, set the oscilloscope parameters to accurately display the signal output by the current probe;

[0034] Stage 5: Perform transfer impedance test: including applying current excitation, measuring voltage signal and calculating transfer impedance;

[0035] Stage 6: Conduct shielding attenuation test: including measuring the electromagnetic field outside the shielding layer and calculating the shielding attenuation;

[0036] Phase 7, data analysis and recording: including analysis and recording, analyzing the transfer impedance and shielding attenuation data obtained from the test, judging whether the performance of the high-voltage cable in the vehicle meets the requirements, and recording the test data and parameters.

[0037] Stage 8: Cleaning and tidying up after the test: This includes removing the current probe from the high-voltage cable in the vehicle, cleaning the test site, and properly storing the test equipment and connecting cables.

[0038] First of all, before testing, the corresponding test standards for shield attenuation and transfer impedance of high-voltage cables in vehicles should be followed, including IEC62153-4-3, IEC62153-4-4, IEC62153-4-5, IEC62153-4-6, IEC62153-4-7, IEC62153-4-9, IEC62153-4-15, etc., and are also compatible with EN50289-1-6, DIN47250, I EC61196-1, VG95214-12, VG95214-13, QC / T1067.1—2017, USCAR37 and LV215 and other standards, as well as group standard T / CSAE-189-2021, etc., prepare current probes and compatible oscilloscopes that meet the test requirements, then place the cable stably in an environment with less electromagnetic interference, then correctly connect the current probe to the oscilloscope, and set the oscilloscope parameters to accurately display the signal, then perform the transfer impedance test, including applying current excitation, measuring the voltage signal and calculating the transfer impedance, and then perform the shielding attenuation test, measuring the electromagnetic field outside the shielding layer and calculating the shielding attenuation, then analyze and record the test data to determine whether the cable performance meets the requirements, and properly keep the test equipment and connecting cables. Finally, clean up the test site and remove the current probe.

[0039] The test requirement parameters include but are not limited to bandwidth and measurement range, and the oscilloscope must have sufficient bandwidth and sampling rate.

[0040] By meeting the test requirements of the test, the bandwidth of the current probe determines the signal frequency range that it can accurately measure, while the bandwidth and sampling rate of the oscilloscope determine its ability to capture and display signal details. When both meet the test requirements, the accuracy and reliability of the test results can be ensured, avoiding errors caused by equipment limitations.

[0041] The parameters of the oscilloscope include but are not limited to vertical sensitivity, horizontal scanning speed and trigger mode.

[0042] It can significantly improve the measurement accuracy, signal readability, time resolution, test repeatability and efficiency when testing the shield attenuation and transfer impedance of high-voltage cables in vehicles, thereby ensuring the accuracy and reliability of the test results.

[0043] Applying current excitation is based on a suitable current source to apply a current signal to the high-voltage cable in the vehicle. Measuring the voltage signal is based on a current probe to measure the current signal on the cable and convert it into a voltage signal and output it to an oscilloscope. Calculating the transfer impedance is based on the measured voltage signal and the applied current signal. According to the definition of transfer impedance, the transfer impedance of the high-voltage cable in the vehicle is calculated.

[0044] A current of a certain magnitude and frequency is applied to the high-voltage cable in the vehicle through a suitable current source, and the current signal on the cable is measured using a current probe and converted into a voltage signal which is output to an oscilloscope. The transfer impedance is then calculated based on the measured voltage signal and the applied current signal. This method can accurately and efficiently evaluate the electrical performance of the high-voltage cable in the vehicle, ensure accurate measurement of the transfer impedance, and provide a reliable basis for cable quality monitoring and performance optimization.

[0045] Measure the electromagnetic field outside the shielding layer by turning off the current source, use the electromagnetic field probe to measure the electromagnetic field strength outside the shielding layer of the high-voltage cable in the vehicle, and calculate the shielding attenuation based on the measured electromagnetic field strength and the current signal inside the cable, according to the definition of shielding attenuation, calculate the shielding attenuation of the high-voltage cable in the vehicle.

[0046] By turning off the current source and using instruments such as electromagnetic field probes to measure the electromagnetic field strength outside the shielding layer of the high-voltage cable in the vehicle, and combining the current signal inside the cable, the shielding attenuation of the cable is calculated based on the definition of shielding attenuation. This method can accurately evaluate the shielding effectiveness of the cable, effectively guide the electromagnetic compatibility and anti-interference design of the cable, and ensure the stable operation of the vehicle's electrical system.

[0047] The current signal size and frequency should meet the test standards, and the transfer impedance is defined as the ratio of secondary voltage to primary current.

[0048] The size and frequency of the current signal are determined according to the test standards and actual needs, and the transfer impedance is calculated based on the definition of the ratio of secondary voltage to primary current. This method ensures the standardization and accuracy of the test, provides a scientific basis for evaluating the electrical performance and electromagnetic compatibility of high-voltage cables in the vehicle, and helps to improve the overall performance and safety of the vehicle's electrical system.

[0049] Shielding attenuation is defined as the logarithm of the ratio of the electromagnetic field strength before shielding to the electromagnetic field strength after shielding.

[0050] Shielding attenuation is defined as the logarithm of the ratio of the electromagnetic field strength before and after shielding. This method can quantitatively evaluate the attenuation effect of the high-voltage cable shielding layer in the vehicle on electromagnetic interference, provide an important basis for optimizing cable shielding design and improving vehicle electromagnetic compatibility, and help ensure the stable operation of the electrical system in a complex electromagnetic environment.

[0051] The data and parameters include but are not limited to current magnitude, frequency, voltage signal, electromagnetic field strength, test time and tester.

[0052] Recording and analyzing comprehensive data and parameters including current size, frequency, voltage signal, electromagnetic field strength, test time and testers helps to ensure the traceability of the test process and the accuracy of the results, providing detailed information support for the performance evaluation and subsequent improvement of the high-voltage cables in the vehicle, and further improving the reliability and safety of the vehicle's electrical system.

[0053] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle, characterized in that: The following steps are involved: Stage 1: Equipment preparation: Select a suitable current probe that meets the test requirement parameters, prepare an oscilloscope to accurately display and record the measurement results, and the current probe should be compatible with the oscilloscope to receive the signal output by the current probe. Phase 2: Test environment preparation: The electromagnetic size of the test environment should be adjusted to avoid the influence of external electromagnetic fields on the test results, and the high-voltage cables in the vehicle should be placed stably; Stage 3: Connecting the test equipment: Correctly clamp the current probe on the high-voltage cable in the vehicle, and use a connecting cable to connect the output end of the current probe to the input end of the oscilloscope; Stage 4: Setting oscilloscope parameters: According to the test requirements, setting the parameters of the oscilloscope to accurately display the signal output by the current probe; Stage 5: Perform transfer impedance test: including applying current excitation, measuring voltage signal and calculating transfer impedance; Stage 6: Conduct shielding attenuation test: including measuring the electromagnetic field outside the shielding layer and calculating the shielding attenuation; Phase 7, data analysis and recording: including analysis and recording, wherein the analysis is to analyze the transfer impedance and shielding attenuation data obtained from the test to determine whether the performance of the high-voltage cable in the vehicle meets the requirements, and the recording is to record the test data and parameters. Stage 8: Cleaning and tidying up after the test: This includes cleaning and tidying up, in which the current probe is removed from the high-voltage cable in the vehicle, and the test site is cleaned up, in which the test equipment and connecting cables are properly stored.

2. The method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 1, characterized in that: The test requirement parameters include but are not limited to bandwidth and measurement range, and the oscilloscope has sufficient bandwidth and sampling rate.

3. The method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 1, characterized in that: The parameters of the oscilloscope include but are not limited to vertical sensitivity, horizontal scanning speed and trigger mode.

4. The method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 1, characterized in that: The applied current excitation is based on a suitable current source to apply a current signal to the high-voltage cable in the vehicle. The measured voltage signal is based on a current probe measuring the current signal on the cable and converting it into a voltage signal and outputting it to an oscilloscope. The calculated transfer impedance is based on the measured voltage signal and the applied current signal, and according to the definition of transfer impedance, the transfer impedance of the high-voltage cable in the vehicle is calculated.

5. The method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 1, characterized in that: The electromagnetic field outside the shielding layer is measured by turning off the current source and using an electromagnetic field probe to measure the electromagnetic field strength outside the shielding layer of the high-voltage cable in the vehicle. The shielding attenuation is calculated based on the measured electromagnetic field strength and the current signal inside the cable, according to the definition of shielding attenuation, to calculate the shielding attenuation of the high-voltage cable in the vehicle.

6. A method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 4, characterized in that: The current signal size and frequency should comply with the test standard, and the transfer impedance is defined as the ratio of the secondary voltage to the primary current.

7. The method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 5, characterized in that: The shielding attenuation is defined as the logarithm of the ratio of the electromagnetic field strength before shielding to the electromagnetic field strength after shielding.

8. The method for testing shielding attenuation and transfer impedance of a high-voltage cable in a vehicle according to claim 1, characterized in that: The data and parameters include but are not limited to current magnitude, frequency, voltage signal, electromagnetic field strength, test time and tester.

Images