Device and method for measuring interference current of vehicle shielding power supply system, terminal and storage medium

Abstract

The invention belongs to the technical field of vehicle detection, and particularly relates to a device and method for measuring interference current of a vehicle shielding power supply system, a terminal and a storage medium, and the device comprises a signal source, a power amplifier, a current injection probe, a receiver, a high-impedance network and at least one current probe. According to the invention, the two ends of the to-be-measured shielding cable are respectively stripped into shielding layers with a plurality of lengths, the two ends of the shielding layers which are not stripped are grounded, and components such as a signal source, a power amplifier, a current injection probe, a current probe, a receiver and a high-resistance network are combined, so that the conduction disturbance current of the shielding cable is accurately measured. By measuring the current signals of the shielding layer position and the non-shielding layer position and calculating the correction factor, the measurement error caused by the mutual inductance effect is effectively corrected, and the accuracy of the measurement data is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of vehicle testing technology, and specifically relates to a measuring device, method, terminal, and storage medium for measuring interference current in a vehicle shielded power supply system. Background Technology

[0002] With the rapid development of electric vehicle technology, the internal electrical systems of vehicles are becoming increasingly complex, encompassing a wide range of applications from low-voltage to high-voltage systems. Low-voltage systems, such as wiper motors, heater motors, air conditioning controllers, and instrument clusters, typically use unshielded cables for power transmission; while high-voltage systems, such as inverters with motors, DC / DC converters, and high-voltage battery packs, generally use shielded cables to ensure electromagnetic compatibility and reduce the impact of electromagnetic interference (EMI) on other electronic devices in the vehicle.

[0003] According to the principle of electromagnetic shielding, the shielded cables of high-voltage systems need to be grounded at both ends to achieve dual shielding of magnetic and electric fields, thereby effectively reducing electromagnetic radiation emissions and improving electromagnetic interference immunity. However, in practical applications, high-voltage components equipped with high-power switching semiconductor devices become the main source of electromagnetic interference, posing a potential threat to the stable operation of vehicle electronic systems.

[0004] To thoroughly analyze and effectively control the electromagnetic interference characteristics of shielded power supply systems, accurate measurement of their conducted interference current (or interference current) is crucial. Traditionally, a combination of an EMI receiver and a current probe is used to directly measure the conducted interference current on the shielded cables of high-voltage systems. While this method achieves non-destructive measurement, it has significant limitations. Specifically, due to the mutual inductance between the core wire and the shielding layer of the shielded cable, when interference current passes through, a voltage is induced in the shielding layer, which in turn forms an induced current when both ends are grounded. This induced current cancels out the magnetic flux generated by the interference current, resulting in the conducted interference current measured directly by the current probe being much smaller than the actual interference current conducted by the core wire, leading to inaccurate measurement data. Summary of the Invention

[0005] To address the shortcomings of existing technologies that directly measure conducted interference current on shielded cables of high-voltage systems using a combination of a receiver and a current probe, which results in inaccurate measurement data due to the mutual inductance between the cable core and the shielding layer, this invention provides a measuring device, method, terminal, and storage medium for measuring interference current in a vehicle shielded power system, thereby solving the aforementioned technical problems.

[0006] In a first aspect, the present invention provides a measuring device for interference current of a vehicle shielded power system, wherein a certain length of shielding layer is stripped from each end of the shielded cable to be tested, and the two ends of the unstripped shielding layer are grounded. The measuring device includes: A signal source is used to generate interference current signals; A power amplifier, connected to the output of a signal source, is used to amplify interference current signals. A current injection probe, connected to the output of a power amplifier, is used to inject amplified interference current into the shielded cable under test. At least one current probe is set at different locations on the shielded cable under test to measure the current signal at the location of the shielded layer and the location without the shielded layer of the shielded cable under test. The receiver, connected to the current probe, is used to receive and analyze current signals. A high-impedance network is connected to one end of the shielded cable under test, while the other end of the shielded cable under test is grounded. At the same time, the other end of the high-impedance network away from the shielded cable under test is grounded; it is used to provide high impedance to ensure unidirectional current flow.

[0007] Secondly, the present invention provides a method for measuring interference current in a vehicle shielded power supply system, applicable to the aforementioned measuring device for interference current in a vehicle shielded power supply system, the method comprising: After injecting interference current into the shielded cable under test using a current injection probe, the receiver receives the current signals measured by the current probe at the locations of the shielded and unshielded layers of the cable under test, and calculates the correction factor for the shielded cable under test based on the received current signals. ; The actual conducted interference current on the cables in the vehicle's shielded power system was measured using the aforementioned current probe. Correction factor for the measured shielded cable Add the corrected interference current data to the measured actual conducted interference current. Separate the differential-mode component and common-mode component from the corrected interference current data; Analyze the contribution of differential-mode and common-mode components in different frequency bands to determine the main interference components.

[0008] A further improvement to this technical solution is that the injected interference current is 100mA or higher.

[0009] Further improvements to this technical solution include a correction factor for the shielded cable under test. The calculation method is as follows: The correction factor for the shielded cable under test is obtained by subtracting the current signal at the shielding layer location from the current signal at the unshielded location of the shielded cable under test. .

[0010] A further improvement to this technical solution is the measurement of the actual conducted interference current on the cables in the vehicle's shielded power system using the aforementioned current probe. The method includes: For a vehicle shielded power supply system with only a positive line P and a negative line N, the positive line current I is measured separately using a current probe. P 1. Measure the negative line current I separately N Simultaneously measure the current I of the positive and negative wires. PN The unit is dBμA; For a vehicle shielded power supply system with three phases (U, V, and W), a current probe is used to measure the actual current of any two phases of the three phases (U, V, and W) individually, and to measure the current I of all three phases (U, V, and W) simultaneously. UVW The unit is dBμA.

[0011] Further improvements to this technical solution include adjusting the correction factor for the measured shielded cable. The corrected interference current data is obtained by adding it to the measured actual conducted interference current. The methods include: For a vehicle shielded power system with only a positive wire P and a negative wire N, the corrected data is as follows: The corrected positive line interference current data is as follows: ; The corrected negative line interference current data is as follows: ; The corrected interference current data for the positive and negative lines are as follows: ; For vehicle shielded power systems with three phases (U, V, and W), a current probe is used to measure the U-phase current I separately. U and separate measurement of phase V current I V The corrected data is as follows: The corrected U-phase line interference current data is as follows: ; The corrected V-phase line interference current data is as follows: ; The corrected interference current data for the U-phase, V-phase, and W-phase three-phase lines are as follows: .

[0012] Further improvements to this technical solution include separating the differential-mode component and the common-mode component in the corrected interference current data, the methods of which include: For a vehicle shielded power supply system with only a positive wire P and a negative wire N, the common-mode current and differential-mode current on the shielded cable core are as follows: The common-mode current is: ; The differential mode current is: ,or ; For a vehicle shielded power supply system with three phases (U, V, and W), the common-mode current and differential-mode current on the shielded cable cores are as follows: The common-mode current is: ; The differential mode current is: ,or .

[0013] Further improvements to this technical solution include analyzing the contribution of differential-mode and common-mode components in different frequency bands to determine the main interference components. The methods include: For a vehicle shielded power supply system with only a positive wire P and a negative wire N, the contributions of the common-mode current and differential-mode current on the shielded cable core are as follows: The contribution of differential mode current is: ; The contribution of common-mode current is: ; For a vehicle shielded power supply system with three phases (U, V, and W), the contributions of common-mode current and differential-mode current on the shielded cable cores are as follows: The contribution of differential mode current is: ; The contribution of common-mode current is: ; The contribution of differential-mode current and common-mode current are compared, and the component with the larger contribution value is taken as the main interference component.

[0014] Thirdly, the present invention provides a terminal, comprising: Processor, memory, among which, This memory is used to store computer programs. The processor is used to retrieve and run the computer program from memory, causing the terminal to perform the terminal method described above.

[0015] Fourthly, the present invention provides a computer storage medium storing instructions that, when executed on a computer, cause the computer to perform the methods described in the above aspects.

[0016] The beneficial effects of this invention are as follows: This invention achieves accurate measurement of conducted interference current in shielded cables by stripping a certain length of shielding layer from each end of the shielded cable under test and grounding the two ends of the unstripped shielding layer. Combined with components such as a signal source, power amplifier, current injection probe, current probe, receiver, and high-impedance network, it enables precise measurement of conducted interference current in shielded cables. By measuring the current signals at the shielded and unshielded locations and calculating correction factors, the measurement error caused by mutual inductance effects is effectively corrected, significantly improving the accuracy of the measurement data.

[0017] This invention not only accurately measures conducted interference current but also effectively separates differential-mode current and common-mode current through specific measurement methods and calculation formulas. This is of great significance for in-depth analysis of electromagnetic interference characteristics and optimization of EMI filter design. By separating differential-mode and common-mode currents, the main interference sources can be identified more accurately, providing strong support for subsequent filter design, thereby improving filter design efficiency and reducing later rectification costs.

[0018] This invention obtains corrected interference current data by calculating a correction factor and adding it to the actual measurement data. Furthermore, by separating differential-mode and common-mode currents and analyzing their contributions at different frequency bands, this invention can identify the main interference components, providing accurate data support for subsequent electromagnetic interference suppression measures. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the measurement principle of a measuring device according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic flowchart illustrating a method according to an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of a terminal provided in an embodiment of the present invention.

[0023] 110 is the signal source, 120 is the power amplifier, 130 is the current injection probe, 140 is the receiver, 150 is the high impedance network, 160 is the current probe, A01 is the core wire, A02 is the dielectric layer, A03 is the shielding layer, and A04 is the insulating sheath. Detailed Implementation

[0024] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] like Figure 1 As shown, this invention provides a measuring device for interference current in a vehicle shielded power system, including a signal source 110, a power amplifier 120, a current injection probe 130, a receiver 140, a high-impedance network 150, and at least one current probe 160. Before measurement, a section of shielded cable of the same material as the shielded cable used in the vehicle shielded power system is cut out, and several lengths of shielding layer A03 are stripped from both ends of this shielded cable (a dielectric layer A02 is provided between the shielding layer A03 and the core wire A01, and an insulating sheath A04 is provided on the outside of the shielding layer A03). Approximately 40cm of shielding layer A03 is stripped from each end, and the two ends of the unstripped shielding layer A03 are grounded. The high-impedance network 150 is currently implemented using an artificial power network.

[0027] Specifically, signal source 110 is used to generate interference current signal; power amplifier 120 is connected to the output of signal source 110 to amplify interference current signal; current injection probe 130 is connected to the output of power amplifier 120 to inject amplified interference current into the shielded cable under test; at least one current probe 160 is set at different positions of the shielded cable under test to measure current signals at the shield layer A03 position and the unshielded layer A03 position of the shielded cable under test; receiver 140 is connected to current probe 160 to receive and analyze current signals; high impedance network 150 is connected to one end of the shielded cable under test, the other end of the shielded cable under test is grounded, and the other end of high impedance network 150 away from the shielded cable under test is grounded; it is used to provide high impedance to ensure unidirectional current flow.

[0028] First, using the aforementioned measuring device, perform offline measurements on shielded cables of the same material to determine the correction factor of the shielded cables used in the vehicle's shielded power system. The actual interference current on the shielded cable used in the vehicle's shielded power system is measured using the current probe 160 in the aforementioned measuring device. Before measurement, the current injection probe 130 is clamped to the cable injection point (…). Figure 1 Position 1 is located in the middle, and the current probe 160 is clamped to the corresponding measurement point, waiting for measurement; the clamping and clamping of the probe is existing technology and will not be described in detail here.

[0029] This invention achieves accurate measurement of conducted interference current in shielded cables by stripping a certain length of shielding layer A03 from both ends of the shielded cable under test, grounding the two ends of the unstripped shielding layer A03, and combining components such as signal source 110, power amplifier 120, current injection probe 130, current probe 160, receiver 140, and high-impedance network.

[0030] Figure 2 This is a schematic flowchart illustrating a method for measuring interference current in a vehicle shielded power supply system provided by the present invention. Wherein, Figure 2 The executing entity is the aforementioned measuring device for interference current in a vehicle shielded power supply system. Depending on different requirements, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0031] like Figure 2 As shown, the method includes: Step 210: After injecting interference current into the shielded cable under test through the current injection probe 130, the receiver 140 receives the current signals at the shielding layer A03 position and the unshielded layer A03 position of the shielded cable under test measured by the current probe 160, and calculates the correction factor of the shielded cable under test based on the received current signals. ; Step 220: Measure the actual conducted interference current on the cables in the vehicle's shielded power system using the aforementioned current probe 160; Step 230: Measure the correction factor of the shielded cable under test. Add the corrected interference current data to the measured actual conducted interference current. Step 240: Separate the differential-mode component and common-mode component in the corrected interference current data; Step 250: Analyze the contribution of differential mode components and common mode components in different frequency bands to determine the main interference components.

[0032] To facilitate understanding of the present invention, the following description further illustrates the method for measuring the interference current of a vehicle shielded power supply system, based on the principle of the present invention and in conjunction with the process of measuring the interference current of the vehicle shielded power supply system in the embodiments.

[0033] During measurement, Figure 1 At position 1, a current of 100mA, 200mA, 300mA, or other interference current is injected into the core wire A01 of the shielded cable under test through the current injection probe 130. Due to the presence of the high-resistance network, the injected current will flow on one side only.

[0034] Simultaneously, using the measurement unit composed of receiver 140 and current probe 160, the conducted disturbance current (or interference current) is measured at position 2 (position of cable with shielded layer A03) and position 3 (position of cable without shielded layer A03), respectively, and recorded as I2 and I3, with the unit being dBμA.

[0035] Furthermore, the correction factor for the shielded cable under test. The calculation method is as follows: The correction factor for the shielded cable under test is obtained by subtracting the current signal at position A03 of the shield layer from the current signal at position A03 of the unshielded shield layer. .

[0036] Specifically, the difference between currents I2 and I3 is calculated and denoted as δ. This is denoted as the correction factor for shielded cables.

[0037] Traditional methods for directly measuring conducted interference current on shielded cables in high-voltage systems can lead to inaccurate measurement data due to the mutual inductance between the cable core A01 and the shielding layer A03. By calculating a correction factor and applying it to the actual measurement data, the measurement error caused by the mutual inductance effect can be effectively corrected, thereby significantly improving the accuracy of conducted interference current measurement.

[0038] The calculation of the correction factor δ provides a quantitative indicator for correcting measurement data. By understanding the specific numerical difference, the influence of the shielding layer A03 on current measurement can be clearly identified, allowing for more precise adjustment and optimization of measurement parameters, thus ensuring the reliability of the measurement results.

[0039] The calculation of the correction factor not only improves the overall measurement accuracy but also provides a foundation for the subsequent separation of differential-mode and common-mode currents. Accurate measurement data is a prerequisite for the separation of differential-mode and common-mode currents, and the application of the correction factor ensures that this prerequisite is met, thereby improving the accuracy and effectiveness of the separation of differential-mode and common-mode currents.

[0040] In addition, the method for measuring the actual conducted interference current on the cables in the vehicle's shielded power system using the aforementioned current probe 160 includes: For a vehicle shielded power supply system with only a positive line P and a negative line N, the positive line current I is measured separately using a current probe 160. P 1. Measure the negative line current I separately N Simultaneously measure the current I of the positive and negative wires. PN The unit is dBμA; For a vehicle shielded power supply system with three phases (U, V, and W), a current probe 160 is used to measure the actual current of any two phases of the three phases (U, V, and W) individually, and the current I of the three phases (U, V, and W) is measured simultaneously using the current probe 160. UVW The unit is dBμA.

[0041] This invention can adapt to and accurately measure conducted interference currents in shielded power systems of different types of vehicles, including DC systems and three-phase AC systems. This comprehensiveness ensures the wide application and effectiveness of the measurement technology in various electric vehicles. Specifically, by separately measuring the positive / negative line currents (IP, IN) and simultaneously measuring both currents (IPN), or separately measuring the currents of any two phases of the three-phase lines and simultaneously measuring the three-phase line current (IUVW), this invention can more accurately capture the conducted interference current characteristics on different cables. This multi-dimensional measurement method helps reduce measurement errors and improve the accuracy and reliability of the data.

[0042] Next, the correction factor of the shielded cable under test will be measured. The corrected interference current data is obtained by adding it to the measured actual conducted interference current. The methods include: For a vehicle shielded power system with only a positive wire P and a negative wire N, the corrected data is as follows: The corrected positive line interference current data is as follows: ; The corrected negative line interference current data is as follows: ; The corrected interference current data for the positive and negative lines are as follows: ; For a vehicle shielded power supply system with three phases (U, V, and W), the U-phase current I is measured separately using a current probe 160. U and separate measurement of phase V current I V The corrected data is as follows: The corrected U-phase line interference current data is as follows: ; The corrected V-phase line interference current data is as follows: ; The corrected interference current data for the U-phase, V-phase, and W-phase three-phase lines are as follows: .

[0043] This invention significantly improves the accuracy of measurement data by adding a correction factor to the actual measured conducted interference current data, thereby correcting measurement errors caused by factors such as the mutual inductance effect of shielded cables. This is crucial for subsequent electromagnetic interference characteristic analysis and EMI filter design.

[0044] In addition, methods for separating the differential-mode and common-mode components in the corrected interference current data include: For a vehicle shielded power supply system with only a positive wire P and a negative wire N, the common-mode current and differential-mode current on the shielded cable core wire A01 are as follows: The common-mode current is: In a system with only P-line and N-line, the common-mode current is in the same direction. The 6 in the above formula is 6dB. The linear form is one-half, because the common-mode current measured by the current probe at the same time is the sum of the currents of the two lines (the differential-mode currents cancel each other out), so it needs to be divided by 2, i.e., 6dB. The differential mode current is: ,or ; For a vehicle shielded power supply system with three phases (U, V, and W), the common-mode current and differential-mode current on the shielded cable core A01 are as follows: The common-mode current is: For a UVW three-phase system, the current measured simultaneously is only the common-mode current (the differential-mode current is 120° out of phase and cancels each other out). Therefore, the measured value is the sum of the common-mode currents on the three lines. The common-mode current on a single line is the measured value divided by 3, which is equivalent to subtracting 9.5dB in dB form. The differential mode current is: ,or .

[0045] This invention, by separating differential-mode and common-mode components, can accurately identify the main sources of electromagnetic interference. Differential-mode current primarily reflects interference caused by potential differences between cables or between a cable and ground, while common-mode current primarily reflects interference caused by potential differences between the cable and ground. This precise identification helps designers more accurately pinpoint electromagnetic interference problems, thereby enabling them to take effective suppression measures.

[0046] Furthermore, the contribution of differential-mode and common-mode components in different frequency bands is analyzed to determine the main interference components. The methods include: For a vehicle shielded power supply system with only a positive wire P and a negative wire N, the contributions of the common-mode current and differential-mode current on the shielded cable core wire A01 are as follows: The contribution of differential mode current is: ; The contribution of common-mode current is: ; For a vehicle shielded power supply system with three phases (U, V, and W), the contributions of common-mode current and differential-mode current on core wire A01 of the shielded cable are as follows: The contribution of differential mode current is: ; The contribution of common-mode current is: ; The contribution of differential-mode current and common-mode current are compared, and the component with the larger contribution value is taken as the main interference component.

[0047] This invention significantly improves the stability and reliability of a vehicle's shielded power supply system by precisely locating and suppressing key interference components. This helps reduce system failures or performance degradation caused by electromagnetic interference, thereby improving the overall vehicle's operational quality and safety.

[0048] Figure 3 This is a schematic diagram of the structure of a terminal 300 provided in an embodiment of the present invention. The terminal 300 can be used to execute the method for measuring the interference current of a vehicle shielded power supply system provided in an embodiment of the present invention.

[0049] The terminal 300 may include a processor 310, a memory 320, and a communication module 330. These components communicate via one or more buses. Those skilled in the art will understand that the server structure shown in the figure does not constitute a limitation of the present invention. It may be a bus topology or a star topology, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0050] The memory 320 can be used to store the execution instructions of the processor 310. The memory 320 can be implemented by any type of volatile or non-volatile memory terminal or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. When the execution instructions in the memory 320 are executed by the processor 310, the terminal 300 is able to perform some or all of the steps in the above method embodiments.

[0051] The processor 310 serves as the control center of the storage terminal, connecting various parts of the electronic terminal via various interfaces and lines. It executes software programs and / or modules stored in the memory 320, and calls data stored in the memory to perform various functions of the electronic terminal and / or process data. The processor can be composed of integrated circuits (ICs), such as a single packaged IC or multiple packaged ICs with the same or different functions connected together. For example, the processor 310 may consist only of a central processing unit (CPU). In this embodiment of the invention, the CPU may have a single processing core or include multiple processing cores.

[0052] The communication module 330 is used to establish a communication channel, enabling the storage terminal to communicate with other terminals. It receives user data sent by other terminals or sends user data to other terminals.

[0053] The present invention also provides a computer storage medium, wherein the computer storage medium may store a program, which, when executed, may include some or all of the steps provided in the embodiments of the present invention. The storage medium may be a magnetic disk, an optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0054] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium such as a USB flash drive, mobile hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, or other media capable of storing program code. It includes several instructions to cause a computer terminal (which may be a personal computer, server, or a second terminal, network terminal, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0055] The same or similar parts between the various embodiments in this specification can be referred to mutually. In particular, the terminal embodiments are basically similar to the method embodiments, so the description is relatively simple, and the relevant parts can be referred to the description in the method embodiments.

[0056] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A vehicle shielding system for measuring interference current of a power supply system, characterized in that, Two ends of the shielding cable to be measured are stripped of a length of shielding layer, and the unstripped shielding layers at both ends are grounded. The measuring device comprises: a signal source (110) for generating an interference current signal; a power amplifier (120) connected to the output of the signal source (110) for amplifying the interference current signal; a current injection probe (130) connected to the output of the power amplifier (120) for injecting the amplified interference current into the shielding cable to be measured; at least one current probe (160) arranged at different positions of the shielding cable to be measured for measuring the current signals at the positions of the shielding layer and the position without shielding layer of the shielding cable to be measured; a receiver (140) connected to the current probe (160) for receiving the current signals and analyzing; a high-impedance network (150) connected to one end of the shielding cable to be measured, the other end of the shielding cable to be measured being grounded, and the high-impedance network (150) being connected to the ground far away from the other end of the shielding cable to be measured for providing high impedance to ensure unidirectional current flow.

2. A method of measuring interference current of a vehicle shielded power supply system, characterized by, The method is suitable for measuring the interference current of the vehicle shielding power supply system according to claim 1, and the method comprises: After injecting the interference current to the measured shielded cable through the current injection probe (130), the receiver (140) receives the current signals measured by the current probe (160) at the shielded position and the unshielded position of the measured shielded cable, and calculates the correction factor of the measured shielded cable based on the received current signals ; measuring the actual conducted interference current on the cable in the vehicle shielding power supply system by the current probe (160); The measured correction factor of the shielded cable under test is added to the measured actual conducted interference current to obtain the corrected interference current data; separating the differential mode component and the common mode component in the corrected interference current data; analyzing the contribution degrees of the differential mode component and the common mode component at different frequency bands to determine the main interference component.

3. The method of claim 2, wherein the measurement of the current of the vehicle shielding power system interference is performed by a current sensor. The injected interference current is 100 mA or above.

4. The method of claim 2, wherein the measurement of the current of the vehicle shielding power system interference is performed by a current sensor. Measured shielded cable correction factor The calculation method is: The current signal at the position of the shielding layer of the measured shielded cable is subtracted from the current signal at the position without the shielding layer of the measured shielded cable to obtain the correction factor of the measured shielded cable .

5. The method of claim 2, wherein the measurement of the current of the vehicle shielding power system interference is performed by a current sensor. The method for measuring the actual conducted interference current on the cable in the vehicle shielding power supply system by the current probe (160) comprises: For a vehicle shielded power supply system with only a positive line P and a negative line N, the positive line current I is measured separately using a current probe (160). P 1. Measure the negative line current I separately N Simultaneously measure the current I of the positive and negative wires. PN The unit is dBμA; For a vehicle shielded power supply system with U-phase, V-phase and W-phase three-phase lines, the actual currents of any two of the U-phase line, V-phase and W-phase three-phase lines are measured separately by using current probes (160), and the currents I UVW of the U-phase, V-phase and W-phase three-phase lines are measured simultaneously by using current probes (160). The measured currents are converted into voltages by using a current-to-voltage converter (170), and the voltages are amplified by using an amplifier (180). The amplified voltages are converted into digital signals by using an A / D converter (190), and the digital signals are processed by using a microcomputer (200). The processed signals are converted into a voltage by using a D / A converter (210), and the voltage is amplified by using an amplifier (220). The amplified voltage is converted into a current by using a voltage-to-current converter (230), and the current is converted 6. The method of claim 5, wherein the measurement of the current of the vehicle shielding power system interference is performed by a current sensor. The measured correction factor for the shielded cable under test is added to the measured actual conducted interference current to obtain the corrected interference current data, the method comprising: for the vehicle shielding power supply system having only the positive line P and the negative line N, the corrected data are: The modified positive electrode line interference current data is: ; The modified negative electrode line interference current data is: ; The corrected positive and negative line interference current data are: ; For the vehicle shielded power supply system with U-phase, V-phase and W-phase three-phase lines, the current probe (160) is used to separately measure the U-phase line current I U and the V-phase line current I V , and the corrected data is: The modified U-phase line interference current data is: ; The modified V-phase line interference current data is: ; The corrected interference current data of the U-phase, V-phase and W-phase three-phase lines are: .

7. The method of claim 6, wherein the measurement of the current of the vehicle shielding power system interference is performed by a current sensor. The method for separating the differential mode component and the common mode component in the corrected interference current data comprises: for the vehicle shielding power supply system having only the positive line P and the negative line N, the common mode current and the differential mode current on the core wire of the shielding cable are respectively: Common mode current is: ; The differential mode current is: or ; for the vehicle shielding power supply system having the U-phase, V-phase and W-phase three-phase lines, the common mode current and the differential mode current on the core wire of the shielding cable are respectively: Common mode current is: ; The differential mode current is: or .

8. The method of claim 7, wherein the measurement of the current of the vehicle shielding power system interference is performed by a current sensor. The method for analyzing the contribution degrees of the differential mode component and the common mode component at different frequency bands to determine the main interference component comprises: for the vehicle shielding power supply system having only the positive line P and the negative line N, the contribution degrees of the common mode current and the differential mode current on the core wire of the shielding cable are respectively: The contribution of the differential mode current is: ; The contribution of the common-mode current is: ; for the vehicle shielding power supply system having the U-phase, V-phase and W-phase three-phase lines, the contribution degrees of the common mode current and the differential mode current on the core wire of the shielding cable are respectively: The contribution of the differential mode current is: ; The contribution of the common-mode current is: ; The contribution degree of the differential mode current is compared with the contribution degree of the common mode current, and the component with the larger contribution degree value is taken as the main interference component.

9. A terminal, characterized by comprising: comprise: a processor; a memory for storing execution instructions of the processor; wherein the processor is configured to execute the method according to any one of claims 2-8.

10. A computer readable storage medium storing a computer program, characterized in that, The program is executed by the processor to implement the method according to any one of claims 2-8.

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