New energy automobile wire harness voltage test method and system

Abstract

The invention relates to the technical field of automobile electronics, in particular to a new energy automobile wire harness voltage testing method and system. The method comprises the following steps: carrying out port calibration on a wire harness to be tested, connecting a power supply side and a load side, executing a no-load power-on test, and outputting a no-load deviation result; if the no-load deviation result is higher than the maximum allowable deviation threshold value, the terminal contact condition of the wire harness to be detected is detected, and the contact firmness is determined; executing a dynamic voltage drop test by using the to-be-tested wire harness, determining a branch voltage drop difference, and evaluating the uniformity of the wire harness; identifying an abnormal branch according to the uniformity of the wire harness; the wire insulation resistance of an abnormal branch is measured, and the overheating risk is evaluated; and detecting the contact melting degree according to the overheating risk and the contact firmness, and recording the electrical performance of the wire harness. According to the invention, the wire uniformity and insulation performance of the new energy automobile wire harness are evaluated based on the automobile electronic technology, so that the fault detection efficiency and maintenance accuracy of the wire harness are improved.

Description

Technical Field

[0001] This invention relates to the field of automotive electronics technology, and in particular to a method and system for testing the voltage of wiring harnesses in new energy vehicles. Background Technology

[0002] Current voltage testing of new energy vehicle wiring harnesses largely relies on manual measurement or single static voltage detection methods to assess the overall electrical performance of the harness. However, new energy vehicle wiring harnesses are typically complex in structure, with numerous branches and long lengths, and variations in conductor cross-sections, terminal connection methods, and load characteristics. Traditional static voltage measurement methods struggle to simultaneously reflect the voltage drop characteristics of each branch under different current conditions, making it difficult to accurately identify abnormal branches or potential fault points. Abnormal terminal detection often relies on experience-based judgment or single-point contact testing, failing to accurately quantify the degree of terminal contact loosening or conductor damage level, leading to the easy overlooking or misjudgment of wiring harness terminal problems. Furthermore, the assessment of conductor insulation performance often employs single measurements or uniform judgments across the entire line, lacking detailed analysis of local insulation degradation and overheating risks, making it difficult to accurately identify high-risk areas. In dynamic voltage drop testing, existing systems often use constant current or simple loading strategies, failing to simulate current fluctuations and pulse impacts in actual operating conditions, resulting in difficulty in accurately quantifying branch voltage differences and insufficient accuracy in identifying abnormal branches. The electrical performance testing system for wire harnesses lacks an automated, closed-loop mechanism for anomaly detection and recording. The repair strategies for abnormal terminals and risk assessments rely heavily on manual operation, making it impossible to simultaneously ensure testing accuracy, operational efficiency, and safety. Summary of the Invention

[0003] Therefore, it is necessary for the present invention to provide a method and system for testing the voltage of wiring harnesses in new energy vehicles, in order to solve at least one of the above-mentioned technical problems.

[0004] To achieve the above objectives, a method for testing the voltage of wiring harnesses in new energy vehicles includes the following steps: Step S1: Perform port calibration on the wiring harness under test, connect it to the power supply side and the load side, perform no-load power-on test, and output the no-load deviation result; Step S2: If the no-load deviation result is higher than the maximum permissible deviation threshold, check the terminal contact of the wire harness under test to determine the contact firmness; Step S3: Perform dynamic voltage drop testing on the harness under test to determine the branch voltage drop difference and evaluate the harness uniformity; identify abnormal branches based on the harness uniformity. Step S4: Measure the insulation resistance of the conductors in the abnormal branch to assess the risk of overheating; based on the risk of overheating and the strength of the contact, detect the degree of contact melting and record the electrical performance of the wire harness.

[0005] Preferably, this specification also provides a testing system for the voltage of a new energy vehicle wiring harness, used to perform the testing method for the voltage of a new energy vehicle wiring harness as described above. The testing system for the voltage of a new energy vehicle wiring harness includes: The no-load power-on test module is used to perform port calibration on the wire harness under test, connect to the power supply side and the load side, perform no-load power-on test, and output no-load deviation results. The terminal contact detection module is used to detect the terminal contact of the wire harness under test and determine the contact firmness if the no-load deviation result is higher than the maximum allowable deviation threshold. The dynamic voltage drop test module is used to perform dynamic voltage drop tests on the harness under test, determine the branch voltage drop difference, evaluate the harness uniformity, and identify abnormal branches based on the harness uniformity. The performance recording module is used to measure the insulation resistance of the conductors in abnormal branches to assess the risk of overheating; based on the risk of overheating and the degree of contact melting, it detects the degree of contact melting and records the electrical performance of the wire harness.

[0006] The beneficial effects of this invention are as follows: (1) By combining port calibration with no-load power-on testing, the voltage of terminals and branches of new energy vehicle wiring harnesses can be accurately measured, ensuring the accurate evaluation of the overall electrical performance of the wiring harness and improving the accuracy and reliability of abnormal branch identification.

[0007] (2) By adopting a comprehensive detection strategy that includes terminal elastic deformation measurement, wire breakage quantification and loosening level classification, the terminal contact firmness can be finely evaluated. This can accurately identify terminal problems ranging from minor to complete failure, which not only improves the accuracy of terminal anomaly detection but also reduces the impact of human judgment error on the test results.

[0008] (3) In the dynamic voltage drop test, the combination of phased current loading and pulse current strategy can fully simulate the current fluctuation of the harness under actual working conditions, realize the accurate quantification of branch voltage drop difference, and break through the limitation of traditional constant current measurement that cannot reflect dynamic characteristics.

[0009] (4) By measuring the insulation resistance of abnormal branches, determining the overheating risk and dividing the risk area, a detailed analysis of the local insulation deterioration and potential overheating risk of the conductor is achieved, ensuring the safety and reliability of the wire harness during operation. At the same time, it provides a quantitative basis for the repair of abnormal terminals and improves the applicability and repeatability of the wire harness testing method. Attached Figure Description

[0010] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Fig. 1This is a schematic diagram of the steps in the method for testing the voltage of a wiring harness in a new energy vehicle according to the present invention. Fig. 2 This is a field diagram of the voltage test of the wiring harness in a new energy vehicle according to the present invention; Fig. 3 This is a schematic diagram of the new energy vehicle wiring harness product in this invention; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0011] The technical method of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0012] Furthermore, the accompanying drawings are merely illustrative of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0013] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0014] To achieve the above objectives, please refer to Figs. 1 to 3 This invention provides a method for testing the voltage of wiring harnesses in new energy vehicles, the method comprising the following steps: Step S1: Perform port calibration on the wiring harness under test, connect it to the power supply side and the load side, perform no-load power-on test, and output the no-load deviation result; In one embodiment, after the harness under test is connected to the power supply side and the load side, port calibration is first performed to eliminate measurement system errors; then, an unloaded power-on test is performed, and voltage is gradually applied (30%-50% in the first stage and 50%-70% of the rated voltage in the second stage). The voltage at the power supply end and the load end is recorded at each sampling time, and the voltage difference is calculated; when the voltage difference exceeds a preset threshold, it is marked as an abnormal sampling point, and finally the unloaded deviation result is output.

[0015] In another embodiment, assuming the length of the harness under test is 3 meters, the number of branches is 8, the sampling frequency is 100Hz per second, a total of 300 sampling points are collected during the no-load power-on test, and the recorded voltage difference range is 0.02V to 0.15V. Among them, about 15 sampling points exceed the maximum allowable deviation of 0.1V, which are marked as abnormal sampling points for subsequent terminal contact detection.

[0016] Step S2: If the no-load deviation result is higher than the maximum permissible deviation threshold, check the terminal contact of the wire harness under test to determine the contact firmness; In one embodiment, when the no-load deviation result exceeds the maximum permissible deviation threshold, a standard indentation force is applied to the terminal using a mechanical probe, the elastic deformation displacement of the terminal is recorded, and the terminal loosening level (slight / moderate / severe / complete failure) is determined by combining the wire breakage detection and the copper wire breakage ratio, and the terminal contact firmness result is output.

[0017] In another embodiment, it is assumed that there are 12 terminals to be tested, of which 4 terminals are slightly loose (copper wire breakage accounts for less than 10% of the total), 2 terminals are moderately loose (breakage accounts for 15%), 1 terminal is severely loose (breakage accounts for 45%), and the remaining terminals are normal; the measured elastic deformation range of the terminals is 0.12-0.48mm, and terminals exceeding the upper limit of 0.45mm are judged as unstable. The final contact firmness level is determined by combining the copper wire breakage ratio.

[0018] Step S3: Perform dynamic voltage drop testing on the harness under test to determine the branch voltage drop difference and evaluate the harness uniformity; identify abnormal branches based on the harness uniformity. In one embodiment, a phased current is applied to the harness under test (initial 10%-20% of the rated current, intermediate 50%-70%, and final pulse current 150%-200%), the instantaneous voltage values ​​of each branch are collected and the average voltage of the branches is calculated, the voltage drop of the branches is determined by the difference in the average values, thereby identifying abnormal branches and outputting the uniformity evaluation result of the harness.

[0019] In another embodiment, assuming the harness has 8 branches, a rated current of 10A, a pulse peak value of 15A, a pulse duration of 15ms, and a cycle period of 0.8s; after collecting the instantaneous voltage data of each branch, the average voltage values ​​of the branches are calculated as follows: Branches 4 and 7 were identified as abnormal branches because their deviations exceeded the 0.05V threshold and were marked for subsequent insulation resistance measurements.

[0020] Step S4: Measure the insulation resistance of the conductors in the abnormal branch to assess the risk of overheating; based on the risk of overheating and the strength of the contact, detect the degree of contact melting and record the electrical performance of the wire harness.

[0021] In one embodiment, disconnect the connectors at both ends of the abnormal branch and clean the joints. Apply a low voltage of 50-100V and maintain it for 10-15 seconds to measure the insulation resistance. If the insulation resistance drops by more than 30% for three consecutive times, define 1.5 times the length of the current path as the first risk area, and the rest as the second risk area. Determine the high / medium overheating risk based on the insulation resistance value, and combine it with the terminal contact firmness to output the contact melting degree and record the electrical performance of the wire harness.

[0022] In another embodiment, assuming that the insulation resistance values ​​measured for branch 4 are 6.5MΩ, 4.2MΩ, and 3.8MΩ respectively for three consecutive times, with a decrease of more than 30% in each case, the first risk area is formed by extending 1.5 times the length along the current path. The insulation resistance value of the first risk area is lower than 5MΩ, triggering a high overheat risk warning. The insulation resistance value of the second risk area is 8MΩ, triggering a medium overheat risk warning. Combined with the measurement of the terminal contact firmness, it is found that the terminal of branch 4 is moderately loose. Finally, the electrical performance of the wire harness is recorded, including the abnormal branch number, risk level, and contact melting condition.

[0023] Of particular importance, the measurement of the insulation resistance of the conductor in the abnormal branch in step S4 includes: Before measurement, isolate any abnormal branches, disconnect the connectors at both ends of the branch and clean the connector surfaces; at the initial stage of measurement, apply a low-voltage test voltage, controlling the voltage range between 50-100 volts, hold for 10-15 seconds, and calculate the wire insulation resistance.

[0024] In one embodiment, before measurement, the abnormal branch to be tested is first isolated: the connectors at both ends of the branch are disconnected, and dust or oxide layers on the connector surfaces are removed with cleaning tools to ensure the contact surfaces are clean and free of impurities. Subsequently, in the initial stage of measurement, a test voltage is applied to the branch in a low-voltage manner, controlling the voltage between 50 and 100 volts, and maintained for 10 to 15 seconds. During this period, the voltage and current values ​​of the conductors are collected using an insulation resistance meter or appropriate measuring device, and the insulation resistance of the branch conductors is calculated to assess the branch's insulation performance and potential abnormal risks. This step can provide safety assurance and benchmark data for subsequent high-voltage testing or dynamic voltage loading.

[0025] In another embodiment, assuming the harness under test contains six abnormal branches, after disconnecting the connectors and cleaning the joints, initial test voltages are applied: 60V for branch 1, 55V for branch 2, 70V for branch 3, 65V for branch 4, 50V for branch 5, and 75V for branch 6, each applied for 12 seconds. The measured wire insulation resistances are 120MΩ, 95MΩ, 150MΩ, 110MΩ, 85MΩ, and 160MΩ, respectively. By comparing the insulation resistance of each branch, branches with abnormal insulation performance can be identified. For example, the low insulation resistance of branches 2 and 5 indicates a potential risk of overheating or leakage; branches with higher insulation resistance are in good condition. This method can provide quantitative basis for subsequent electrical performance analysis and abnormal branch location.

[0026] Of particular importance, the assessment of overheating risk in step S4 includes: When the insulation resistance of a conductor decreases by more than 30% for three consecutive times, it is determined to be an effective overheating degradation. The conductor segment corresponding to the degradation is extended along the current path by 1.5 times the length to form the first risk area, and the remaining conductor segments are designated as the second risk area. In one embodiment, the insulation resistance of each conductor segment is monitored during continuous measurement. If the insulation resistance of a conductor decreases by more than 30% in three consecutive samplings, it is determined to have effective overheating degradation. Subsequently, a first risk zone is defined, extending 1.5 times the length forward and backward along the current path from the center of the degraded segment; the remaining conductor segments without obvious degradation are defined as the second risk zone. This division provides a clear spatial positioning basis for subsequent risk assessment and early warning.

[0027] In another embodiment, assuming the wiring harness under test has eight conductors, the insulation resistance value of each conductor is collected three times consecutively, and the decrease is calculated. The measurement results show that conductor 1 decreased by 32%, conductor 3 by 35%, conductor 5 by 40%, and the decrease in the remaining conductors was less than 20%. According to the rules, conductors 1, 3, and 5 are designated as the first risk area (lengths of 45cm, 60cm, and 50cm respectively) by extending them 1.5 times along the current path, and the remaining conductors are designated as the second risk area. This method can visually display the spatial distribution of potential overheating degradation, providing a reference for subsequent safety control or maintenance.

[0028] A high overheating risk warning is triggered when the insulation resistance value in the first risk area is less than 5MΩ, and a medium overheating risk warning is triggered when the insulation resistance value in the second risk area is less than 10MΩ.

[0029] In one embodiment, within a first risk area, when the insulation resistance value is below 5 MΩ, the system triggers a high overheat risk warning; within a second risk area, when the insulation resistance is below 10 MΩ, a medium overheat risk warning is triggered. By setting different thresholds for different risk areas, tiered warnings are achieved, ensuring that potential overheating or insulation damage problems can be detected in a timely manner during electrical load operation.

[0030] In another embodiment, assuming that during continuous monitoring, the insulation resistances in the first risk area are 4.5 MΩ, 4.2 MΩ, and 4.8 MΩ, respectively, and the insulation resistances in the second risk area are 9.5 MΩ, 9.0 MΩ, 8.7 MΩ, and 10.5 MΩ, respectively. Based on preset thresholds, a high overheating risk warning is triggered in the first risk area, a medium overheating risk warning is triggered for the three conductors in the second risk area, while the conductor with an insulation resistance of 10.5 MΩ does not trigger a warning. This determination provides a quantitative basis for subsequent maintenance prioritization and line safety analysis.

[0031] Preferably, the no-load power-on test performed in step S1 includes: Before performing the no-load power-on test, check the condition of the wiring harness terminals and repair any abnormal wiring harness terminals. In one embodiment, before performing the no-load power-on test, the appearance and contact firmness of the terminals of the harness under test are first inspected, including the measurement of terminal elastic deformation and the detection of contact resistance. For any loose, oxidized or slightly damaged terminals, standard tools are used to repair or replace them to ensure that the terminals are in a normal connection state, so as to ensure the reliability of the subsequent no-load power-on test.

[0032] In another embodiment, it is assumed that the harness under test has 10 terminals, of which 3 terminals are slightly loose (contact resistance 0.12–0.18Ω, higher than the normal threshold of 0.1Ω) and 1 terminal has surface oxidation (contact resistance 0.25Ω). After repair, the contact resistance of all terminals is restored to the range of 0.08–0.1Ω, providing a qualified prerequisite for no-load power-on test.

[0033] During the no-load energization process, the rated voltage is applied gradually. In the first stage, 30% to 50% of the total voltage is applied, and in the second stage, the remaining 50% to 70% is applied. In one embodiment, an open-circuit voltage test is applied to the wiring harness of the repaired terminal using a phased application strategy: in the first phase, 30%-50% of the total rated voltage is applied and maintained for several seconds to record the initial response; in the second phase, the remaining 50%-70% of the rated voltage is applied and a stable acquisition state is maintained to avoid terminal damage or measurement abnormalities caused by a one-time overvoltage.

[0034] In another embodiment, assuming the rated voltage of the harness is 12V, the first stage applies 3.6–6V for 5s; the second stage applies 6–8.4V for 10s. By gradually applying the voltage, the dynamic curve of the harness voltage response changing with the stage can be observed, providing a data basis for subsequent identification of abnormal sampling points.

[0035] At each sampling moment, the voltage at the power supply terminal and the voltage at the load terminal are collected, and the corresponding time interval is recorded; In one embodiment, the power supply voltage and load voltage are synchronously acquired at each sampling time, and the corresponding sampling time interval is recorded to ensure the timing consistency of the acquired data; at the same time, the sampled data is filtered in real time to remove transient noise interference and generate a continuous and stable voltage time series.

[0036] In another embodiment, assuming a sampling frequency of 100Hz, a harness length of 3 meters, a total acquisition time of 15 seconds, and a total of 1500 sampling points; the average value of the power supply voltage variation over the period is... The average voltage at the load end is The corresponding time intervals are all 0.01s, providing accurate input for subsequent voltage difference calculations.

[0037] After the data acquisition is completed, the voltage difference between the power supply end and the load end is calculated at each sampling time, and sampling points where the voltage difference exceeds the preset voltage threshold are marked as abnormal sampling points.

[0038] In one embodiment, the difference between the power supply voltage and the load voltage at each sampling time is calculated. If the difference exceeds a preset voltage threshold, the sampling point is marked as an abnormal sampling point for subsequent harness uniformity assessment and terminal contact status analysis.

[0039] In another embodiment, assuming a preset voltage threshold of 0.05V, the calculated voltage difference sequence (in V) for each sampling point is as follows: Among them, 45 sampling points, including frames 2, 4, and 7, which exceeded 0.05V, were marked as abnormal sampling points, indicating potential poor terminal contact or uneven local conductor impedance, which facilitates subsequent dynamic voltage drop testing and uniformity assessment.

[0040] Preferably, checking the condition of the wire harness terminals includes: Fix the wire harness to be tested on the wire harness bracket; set contact test points on the terminal surface of the wire harness to be tested; apply mechanical force to the contact test points through a mechanical probe and record the elastic deformation of the terminal; In one embodiment, the wire harness to be tested is fixed on a standard wire harness bracket to ensure that the position of the wire harness is stable throughout the test; contact test points are set on the surface of each terminal, and a mechanical probe is used to apply controllable mechanical force to each terminal one by one, and the elastic deformation (displacement) generated by the terminal is recorded for subsequent judgment of the terminal contact status.

[0041] In another embodiment, it is assumed that the wire harness under test has 12 terminals, and each terminal has 2 contact measurement points on its terminal surface. The mechanical probe applies a force of 0.5 N, and the measured elastic deformation (displacement, in mm) sequence of the terminals is as follows: These measurements provide a quantitative basis for subsequent assessments of terminal integrity and loosening.

[0042] The displacement is measured based on the elastic deformation of the terminal, the breakage of the terminal wire is detected, the degree of loosening is determined, and the terminal is marked as abnormal. The status of all abnormal terminals is recorded.

[0043] In one embodiment, based on the terminal elastic deformation measured in step S1, it is determined whether the terminal wire is broken or loose; for terminals exceeding a preset threshold, they are marked as abnormal terminals, and their status information is recorded in the detection log for subsequent maintenance or troubleshooting.

[0044] In another embodiment, assuming a preset elastic deformation threshold of 0.20 mm, terminals with measured elastic deformation exceeding the threshold (terminals 3, 7, and 11) are identified as abnormal terminals. Specifically, terminal 3 has an elastic deformation of 0.25 mm, indicating a slight wire breakage; terminal 7 has an elastic deformation of 0.30 mm, indicating severe terminal loosening; and terminal 11 has an elastic deformation of 0.20 mm, indicating loose terminal contact edges. All abnormal terminal numbers and elastic deformation values ​​are recorded in the inspection report for subsequent maintenance or no-load power-on testing preparation.

[0045] Preferably, the displacement measurement based on the elastic deformation of the terminal includes: Before the terminal is clamped, the initial spatial coordinates of the terminal in an unforced state are recorded; during the application of the standard clamping force, continuous displacement points on the terminal surface are collected and a displacement curve is formed; the maximum displacement value relative to the initial spatial coordinates is extracted from the displacement curve as the elastic deformation of the terminal under the standard clamping force. In one embodiment, the terminal under test is fixed on a standard test fixture. First, the initial spatial coordinates of the terminal in its unloaded state are recorded for reference in subsequent displacement measurements. Then, a standard indentation force is applied, and continuous displacement points on the terminal surface are collected using a mechanical probe or force control device, forming a displacement curve. The displacement curve is processed, and the maximum displacement value relative to the initial spatial coordinates is extracted as the elastic deformation of the terminal under the standard indentation force, providing a quantitative basis for terminal contact state analysis.

[0046] In another embodiment, assuming there are 10 terminals to be tested, and the sampling frequency of the continuous displacement points of each terminal under the pressure is 1kHz, the measured maximum elastic displacement (unit mm) sequence is as follows: These displacement values ​​can be used to assess the elastic response and stability of the terminals during pressure application, and provide basic data for subsequent terminal anomaly detection.

[0047] The elastic deformation is compared with the preset displacement threshold range. If the displacement is less than the lower limit, it is determined to be insufficient contact. If it is greater than the upper limit, it is determined to be terminal instability. After the comparison is completed, the displacement data under insufficient contact and terminal instability are linearly fitted and recorded as the displacement.

[0048] In one embodiment, the elastic deformation of the terminal obtained in step S1 is compared with a preset displacement threshold range. If the maximum displacement of the terminal is less than the lower limit, the terminal is determined to have insufficient contact; if it is greater than the upper limit, the terminal is determined to be unstable or may be loose. After the comparison is completed, the elastic displacement data of all terminals are linearly fitted, and the fitting result is recorded as the terminal displacement amount for subsequent terminal reliability analysis and fault diagnosis.

[0049] In another embodiment, assuming a preset elastic displacement threshold range of 0.08 mm to 0.20 mm: terminals with a maximum measured displacement less than 0.08 mm (terminals 1, 3, and 6) are considered to have insufficient contact; terminals with a maximum measured displacement greater than 0.20 mm (terminals 4, 7, and 10) are considered to have terminal instability. After linear fitting of the elastic displacement of all terminals, the slope of the fitted curve ranges from 0.95 to 1.05, and the average mean square error of the fitting is 0.003 mm². Recording the fitting results can provide a quantitative reference for terminal quality assessment, clamping process optimization, and electrical performance testing.

[0050] Preferably, detecting broken terminal wires includes: Separate the test terminal wire of the wire harness to be tested from the connector, measure the continuity between the two ends of the wire, perform segment-by-segment bending test on the wire, with bending angles of 90 degrees to 120 degrees and intervals of 1 to 3 centimeters; monitor the change in resistance value during bending, mark the locations where the resistance value jumps, and record them as suspected fracture areas; In one embodiment, the test terminal wires of the wire harness under test are separated from the connector to ensure that the terminal contact state is independently controllable. The wires are subjected to segment-by-segment bending tests, with bending angles set between 90° and 120° and bending intervals between 1cm and 3cm. During the test, the changes in wire resistance are monitored in real time using a high-precision digital multimeter or a resistance acquisition device. Locations showing resistance jumps are marked as suspected fracture zones, and the three-dimensional coordinates or wire length position of these locations are recorded to provide reference data for subsequent wire damage analysis.

[0051] In another embodiment, assuming the length of the conductor under test is 30cm, it is divided into 10 segments for bending tests, with an interval of 3cm and a fixed bending angle of 110°. The sequence of collected resistance values ​​(unit: Ω) is as follows: The resistance jumps in segments 4 and 8 (0.35Ω and 0.40Ω respectively) indicate potential fracture zones. This hypothetical example can be used to simulate actual bending detection and fracture risk location.

[0052] In the suspected fracture area, the insulation layer is removed, the condition of the internal conductor bundle is inspected, and the number of broken copper wires is counted. The total number of copper wires is compared with the total number of copper wires in the standard wire gauge to calculate the fracture ratio and determine the damage level of the conductor.

[0053] In one embodiment, for the suspected fracture area marked in step S1, the insulation layer of the wire is removed to inspect the condition of the internal copper conductor bundle. The number of fractured copper wires is counted and compared with the total number of copper wires in the standard wire gauge to calculate the fracture ratio. The wire damage level is determined based on the fracture ratio, such as minor damage, moderate damage, or severe damage, and the damage level of each wire segment is recorded to provide a basis for wire harness repair, replacement, or reliability assessment.

[0054] In another embodiment, assuming the total number of copper wires inside the suspected fracture zone is 7, the inspection results are as follows: 2 copper wires are broken in segment 4, and 3 copper wires are broken in segment 8. Therefore, the fracture rate of segment 4 is 2 / 7 ≈ 28.6%, which is judged as moderate damage; the fracture rate of segment 8 is... The damage was determined to be severe. By statistically analyzing the fracture ratio of all suspected fracture zones, a damage distribution map of the wiring harness can be drawn, providing a quantitative reference for subsequent repair or quality analysis.

[0055] Preferably, determining the degree of loosening includes: The following criteria define a slight loosening: the number of broken copper wires is less than 10% of the total number of copper wires; the number of broken copper wires is 10%-30% of the total number of copper wires; the number of broken copper wires is 30%-60% of the total number of copper wires; and the number of broken copper wires is more than 60% of the total number of copper wires or the wire is completely broken, which is defined as complete failure.

[0056] In one embodiment, the total number of copper wires in each conductor of the wiring harness of the new energy vehicle under test is obtained. The copper wire diameter is approximately 0.2mm, and the total length is recorded according to the harness design length. A combination of a high-definition industrial camera (4096×2160 resolution) and an optical microscope was used to capture images of the wire end faces under uniform illumination. At least five fields of view were captured for each wire end face to ensure that all copper wires across the cross-section could be identified. Image processing algorithms were used to identify the edge contour of each copper wire and to calculate the actual number of identifiable copper wires. Then, through visual inspection and algorithm verification, copper wires that could not be identified or were obviously broken were included in the count of broken copper wires. Calculate the fracture ratio The fracture ratio is classified according to a preset standard: when At that time, it was determined to be slightly loose; At that time, it was determined to be moderate loosening; At that time, it was determined to be severely loose; If the entire conductor breaks, it is considered a complete failure. Each conductor... , , The classification results are recorded in tabular form, with data including conductor number, total number of copper wires, number of broken copper wires, breakage rate (%), and classification number.

[0057] In another embodiment, assuming a conductor has a total of 50 copper wires, a high-definition end-face image detection system and macro optical imaging identify 3 broken copper wires, and the breakage ratio is calculated. The first wire was determined to be slightly loose; the second wire had 12 broken copper wires. The condition was determined to be moderately loose; the third conductor had 28 broken copper wires. The fourth conductor was determined to be severely loose; 35 of its components were broken or the entire conductor was disconnected. The copper wire was determined to be completely faulty. During the inspection, the location of the copper wire break was marked using image coordinates, and the end face coordinates were converted from pixel positions to physical millimeter positions and recorded in the database.

[0058] Preferably, repairing abnormal wire harness terminals includes: If the abnormal wire harness terminal is slightly loose, fill and bond the broken copper wire, apply silver conductive paint to the broken area to form a conductive bridging layer, and re-wrap and seal the insulation layer of the damaged section. In one embodiment, when the number of broken copper wires at the abnormal wiring harness terminal is no more than 10% of the total number of copper wires, the location and number of broken copper wires are first confirmed using a high-definition optical microscope (5 μm resolution). At the broken area, a micro-precision syringe (0.2 mm needle diameter) is used to apply silver conductive paint (conductivity ≥10). 6 A conductive varnish (S / m) is applied between the broken copper wires to ensure a continuous conductive bridging layer. After filling, the conductive varnish is cured at room temperature for 10 minutes. Then, polyethylene insulating tape is used to wrap the broken area with a thickness of approximately 0.5 mm, covering 3 mm before and after the broken section, to ensure insulation integrity and electrical isolation. The insulation resistance of the wrapped insulation layer is measured using an insulation resistance meter (range 0–1000 MΩ, test voltage 500 V) to ensure a minimum insulation resistance. This was to verify that the bandage was intact. The entire operation was performed using a microscope for observation and positioning assistance to ensure uniform filling and no short circuits between the copper wires.

[0059] In another embodiment, assuming a wiring harness terminal has a total of 50 copper wires, including 3 broken copper wires with a break length of approximately 2 mm, the broken areas are filled with 0.15 mm thick silver conductive paint, and then covered with 3 mm of insulating tape on both the front and back, for a total coverage length of 8 mm. The curing time is 12 minutes, and the insulation resistance measurement result is 120 MΩ. During the filling process, a microscope at 20x magnification is used to ensure that each broken copper wire is covered with silver paint and forms a continuous conductive bridge.

[0060] If the abnormal wire harness terminal is moderately loose, leave 5-10 mm of intact wire segment before and after the breakage point, and cut off the damaged part; use a jumper of the same specification to repair by overlapping, with an overlap length of not less than 15 mm; use heat shrink tubing to insulate and seal the overlap area. In one embodiment, when 10%–30% of the broken copper wires in the abnormal wiring harness terminals are broken, a 5–10 mm section of intact copper wire is left before and after the breakage as a reference for splicing and repair. The damaged section of wire is cut off using precision wire cutters, ensuring a clean, burr-free cut. A single-strand copper wire of the same specification as the original wire is used as a jumper. Both ends of the jumper are spliced ​​to the remaining ends of the original wire, with a splice length of not less than 15 mm. The splice area is continuously tested with a multimeter to confirm good conductivity, with the jumper resistance ≤50 mΩ. After splicing, the splice section is first wrapped with one layer of PTFE film, then heat-shrink tubing (shrinkage ratio 2:1, tubing diameter matching the outer diameter of the splice section) is used for heat shrinking at 120°C for 60 seconds, forming an insulation layer approximately 0.5 mm thick. After shrinking, an insulation resistance meter is used to test the insulation resistance, ensuring it is ≥100 MΩ. Simultaneously, a tensile tester is used to measure the tensile strength of the splice section, ensuring it is ≥30 N.

[0061] In another embodiment, assuming a 7mm intact conductor segment is removed before and after the damaged section, 16AWG copper wire of the same specification is used as the jumper wire, with an overlap length of 18mm. The heat shrink tubing is heated to 125°C and the shrinkage time is 65 seconds. After shrinkage, the thickness is approximately 0.52mm, the resistance of the overlap segment is measured to be 45mΩ, the insulation resistance is 115MΩ, and the tensile strength of the overlap segment is 32N. During this process, the overlap position of each overlap segment is recorded using a macro camera to ensure accurate positioning and neat conductor arrangement.

[0062] If the abnormal wire harness terminal is severely loose, cut off the entire damaged section of the wire and extend and repair it, using heat shrink tubing for double insulation protection; if the abnormal wire harness terminal is completely ineffective, re-crimp the terminal.

[0063] In one embodiment, for severely loosened wire harness terminals (with 30%–60% of the copper wires broken), the entire damaged section of the conductor is first cut off, and then extended and repaired using copper wire of the same specification. The length of the extension section is adjusted according to whether the original conductor is too short, typically 50–100 mm. 5 mm of insulation is stripped from both ends of the extension conductor, and the extension conductor end is crimped to the original conductor end using mechanical crimping pliers with a crimping force of 150 N to ensure a firm contact. After crimping, double insulation protection is provided using heat shrink tubing: first, one layer of heat shrink tubing is applied to the crimped end at a shrinking temperature of 120°C for 60 seconds; then another layer of heat shrink tubing is applied around the crimped end under the same shrinking conditions, forming a double-layer insulation protection with a thickness of approximately 1 mm. For terminals that are completely failed (more than 60% of the total number of broken copper wires or the wires are completely broken), the terminals are re-crimped using a crimping machine. The crimping parameters are set to 200N and the crimping time is 3 seconds to ensure a firm mechanical connection between the wires and the terminals. Then, heat shrink tubing is used for insulation encapsulation with a thickness of about 0.5mm. Continuity and insulation tests are performed using a multimeter and an insulation resistance meter.

[0064] In another embodiment, assuming a wire harness terminal is severely loose, with 28 broken copper wires out of a total of 50, a 30mm damaged section is removed, the copper wire length is extended by 70mm, and 5mm of insulation is stripped. The mechanical crimping force is 155N, and the crimping time is 2.8 seconds. Two layers of heat shrink tubing are applied, with a shrinking temperature of 122°C and a shrinking time of 62 seconds, resulting in a final thickness of 1.05mm. The conduction resistance of the crimped section is 40mΩ, and the insulation resistance is 120MΩ. For completely failed terminals, the terminals are re-crimped with parameters of 200N and a crimping time of 3 seconds. After crimping, the insulation tubing thickness is 0.52mm, the conduction resistance is 35mΩ, and the insulation resistance is 125MΩ. The operation records are kept complete for subsequent quality tracking.

[0065] Preferably, step S3, which involves performing a dynamic voltage drop test using the wire harness under test, includes: In the initial stage of testing, the current is applied to 10% to 20% of the rated current; in the intermediate stage, the current is gradually increased to 50% to 70% of the rated current. In one embodiment, the test process begins by connecting the new energy vehicle wiring harness under test to the test bench and connecting a high-precision constant current power supply (adjustable output current, resolution 0.01A, maximum output 200A). Initially, the output current is set to 10%–20% of the rated current; for example, if the rated current is 50A, the initial load current is 5A–10A. A gradual current increase mode is used, with the current rise rate controlled within 1A / ms to reduce transient impact. The load is applied continuously for 30 seconds, while a high-sampling-rate data acquisition system (sampling rate 10kHz) records the wiring harness terminal voltage, current, and temperature information. Subsequently, in the intermediate stage, the current is gradually increased to 50%–70% of the rated current; for example, from a 50A rated current to 25A–35A. The current increase is divided into five equal steps, each maintained for 5 seconds, to ensure stable dynamic response. Throughout the current loading process, a digital multimeter and a high-frequency voltage probe are used to simultaneously collect the voltage drop, and the collected data is stored in real-time to a computer for subsequent electrical characteristic analysis and anomaly identification.

[0066] In another embodiment, assuming the rated current of the harness under test is 60A, the initial stage load is 6A (10%) to 12A (20%), increasing by 2A every 2 seconds; in the intermediate stage, the current is gradually increased in six steps to 36A (60%)–42A (70%), with each step held for 4 seconds. An oscilloscope and data acquisition module are used to record the voltage change at each step, with the current rise rate set to 0.8A / ms, the initial temperature at 25°C, and the ambient humidity at 50% to ensure reproducibility of the experimental parameters.

[0067] In the final stage, a rectangular pulse current is applied, with the pulse rising edge abruptly changing from 0 Amperes to the peak current within 1 millisecond. The pulse peak is set to 150% to 200% of the rated current, and the pulse current is maintained for 10 to 20 milliseconds before dropping to 0 Amperes within 1 millisecond. In the pulse repetition stage, the pulse period is set to cycle between 0.5 and 1 second.

[0068] In one embodiment, in the final stage, a rectangular pulse current is applied via a constant current power supply. The pulse rise time abruptly jumps from 0A to the peak current within 1 millisecond, and the pulse peak value is set to 150%–200% of the rated current, for example, 75A–100A when the rated current is 50A. The pulse is maintained for 10–20 milliseconds, and then rapidly drops to 0A within 1 millisecond. The pulse repetition phase employs a periodic cycle with a period set to 0.5–1 second to ensure that the interval between pulses is sufficient to measure the recovery state of the harness. During the test, a high-speed current probe (response time ≤0.1μs) and a high-frequency sampling oscilloscope (sampling rate ≥1MHz) are used to record the current waveform and corresponding terminal voltage, ensuring that the peak value, rise time, and fall time meet the set specifications. The harness temperature change is also recorded simultaneously to evaluate the electrical transient response.

[0069] In another embodiment, assuming the rated current of the harness under test is 60A, a pulse peak of 90A (150%) to 120A (200%) is applied, with a rise time of 0.8ms, a pulse duration of 15ms, and a fall time of 0.9ms. The pulse repetition period is set to 0.7 seconds, and the pulses are cycled 20 times. A high-speed oscilloscope with a sampling rate of 1.25MHz and a current probe bandwidth of 100kHz is used to record the peak value, duration, and fall time of each pulse, and the terminal temperature is measured, assuming a peak temperature rise of 3°C, to ensure that the data is used for dynamic voltage drop analysis and abnormal branch identification.

[0070] Preferably, determining the branch voltage drop in step S3 includes: Collect the instantaneous voltage value of each branch; calculate the average instantaneous voltage value of each branch under the same current stage to obtain the branch voltage average; use the branch voltage average to determine the branch voltage drop.

[0071] In one embodiment, during the initial testing phase, instantaneous voltage values ​​are simultaneously collected from each branch of the harness under test. After collection, the instantaneous voltage values ​​of each branch under the same current condition are averaged to obtain the average voltage value of that branch. Subsequently, the voltage drop difference between different branches is calculated using the average voltage values ​​of each branch to evaluate the consistency and uniformity of the voltage across branches, thereby identifying any potentially abnormal branches. This method can provide foundational data for subsequent dynamic voltage drop analysis and abnormal branch identification.

[0072] In another embodiment, assuming the harness under test has five branches, under the same current conditions, the average voltages of each branch are measured to be approximately 12.05V, 11.98V, 12.12V, 12.00V, and 12.07V, respectively. By comparing these average voltage values, the voltage drop difference between branches can be obtained. For example, larger values ​​such as 0.14V and 0.12V indicate significant differences between branches, suggesting possible localized poor contact or abnormal wire resistance. Smaller voltage drop differences indicate uniform branch voltages and a normal harness condition. In this way, branches with abnormal voltage can be visually identified and located, providing a reference for subsequent maintenance or repair.

[0073] Therefore, the embodiments should be considered as exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the application are intended to be included within the invention.

[0074] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for testing the voltage of wiring harnesses in new energy vehicles, characterized in that, Includes the following steps: Step S1: Perform port calibration on the wiring harness under test, connect it to the power supply side and the load side, perform no-load power-on test, and output the no-load deviation result; Step S2: If the no-load deviation result is higher than the maximum permissible deviation threshold, check the terminal contact of the wire harness under test to determine the contact firmness; Step S3: Perform a dynamic voltage drop test on the harness under test to determine the branch voltage drop difference and evaluate the uniformity of the harness; Identify abnormal branches based on harness uniformity; Step S4: Measure the insulation resistance of the conductors in the abnormal branch to assess the risk of overheating; based on the risk of overheating and the strength of the contact, detect the degree of contact melting and record the electrical performance of the wire harness.

2. The method for testing the voltage of a new energy vehicle wiring harness according to claim 1, characterized in that, Step S1, which involves performing a no-load power-on test, includes: Before performing the no-load power-on test, check the condition of the wiring harness terminals and repair any abnormal wiring harness terminals. During the no-load energization process, the rated voltage is applied gradually. In the first stage, 30% to 50% of the total voltage is applied, and in the second stage, the remaining 50% to 70% is applied. At each sampling moment, the voltage at the power supply terminal and the voltage at the load terminal are collected, and the corresponding time interval is recorded; After the data acquisition is completed, the voltage difference between the power supply end and the load end is calculated at each sampling time, and sampling points where the voltage difference exceeds the preset voltage threshold are marked as abnormal sampling points.

3. The method for testing the voltage of a new energy vehicle wiring harness according to claim 2, characterized in that, Checking the condition of the wire harness terminals includes: Fix the wire harness to be tested on the wire harness bracket; set contact test points on the terminal surface of the wire harness to be tested; apply mechanical force to the contact test points through a mechanical probe and record the elastic deformation of the terminal; The displacement is measured based on the elastic deformation of the terminal, the breakage of the terminal wire is detected, the degree of loosening is determined, and the terminal is marked as abnormal. The status of all abnormal terminals is recorded.

4. The method for testing the voltage of a new energy vehicle wiring harness according to claim 3, characterized in that, The displacement is measured based on the elastic deformation of the terminal, including: Before the terminal is clamped, the initial spatial coordinates of the terminal in an unforced state are recorded; during the application of the standard clamping force, continuous displacement points on the terminal surface are collected and a displacement curve is formed; the maximum displacement value relative to the initial spatial coordinates is extracted from the displacement curve as the elastic deformation of the terminal under the standard clamping force. The elastic deformation is compared with the preset displacement threshold range. If the displacement is less than the lower limit, it is determined to be insufficient contact. If it is greater than the upper limit, it is determined to be terminal instability. After the comparison is completed, the displacement data under insufficient contact and terminal instability are linearly fitted and recorded as the displacement.

5. The method for testing the voltage of a new energy vehicle wiring harness according to claim 3, characterized in that, Detection terminal wire breakage includes: Separate the test terminal wire of the wire harness to be tested from the connector, measure the continuity between the two ends of the wire, perform segment-by-segment bending test on the wire, with bending angles of 90 degrees to 120 degrees and intervals of 1 to 3 centimeters; monitor the change in resistance value during bending, mark the locations where the resistance value jumps, and record them as suspected fracture areas; In the suspected fracture area, the insulation layer is removed, the condition of the internal conductor bundle is inspected, and the number of broken copper wires is counted. The total number of copper wires is compared with the total number of copper wires in the standard wire gauge to calculate the fracture ratio and determine the damage level of the conductor.

6. The method for testing the voltage of a new energy vehicle wiring harness according to claim 3, characterized in that, Determining the degree of loosening includes: The following criteria define a slight loosening: the number of broken copper wires is less than 10% of the total number of copper wires; the number of broken copper wires is 10%-30% of the total number of copper wires; the number of broken copper wires is 30%-60% of the total number of copper wires; and the number of broken copper wires is more than 60% of the total number of copper wires or the wire is completely broken, which is defined as complete failure.

7. The method for testing the voltage of a new energy vehicle wiring harness according to claim 3, characterized in that, Repairing abnormal wire harness terminals includes: If the abnormal wire harness terminal is slightly loose, fill and bond the broken copper wire, apply silver conductive paint to the broken area to form a conductive bridging layer, and re-wrap and seal the insulation layer of the damaged section. If the abnormal wire harness terminal is moderately loose, leave 5-10 mm of intact wire segment before and after the breakage point, and cut off the damaged part; use a jumper of the same specification to repair by overlapping, with an overlap length of not less than 15 mm; use heat shrink tubing to insulate and seal the overlap area. If the abnormal wire harness terminal is severely loose, cut off the entire damaged section of the wire and extend and repair it, using heat shrink tubing for double insulation protection; if the abnormal wire harness terminal is completely ineffective, re-crimp the terminal.

8. The method for testing the voltage of a new energy vehicle wiring harness according to claim 1, characterized in that, Step S3, which involves performing a dynamic voltage drop test using the harness under test, includes: In the initial stage of testing, the current is applied to 10% to 20% of the rated current; in the intermediate stage, the current is gradually increased to 50% to 70% of the rated current. In the final stage, a rectangular pulse current is applied, with the pulse rising edge abruptly changing from 0 Amperes to the peak current within 1 millisecond. The pulse peak is set to 150% to 200% of the rated current, and the pulse current is maintained for 10 to 20 milliseconds before dropping to 0 Amperes within 1 millisecond. In the pulse repetition stage, the pulse period is set to cycle between 0.5 and 1 second.

9. The method for testing the voltage of a new energy vehicle wiring harness according to claim 1, characterized in that, Determining the branch voltage drop in step S3 includes: Collect the instantaneous voltage value of each branch; calculate the average instantaneous voltage value of each branch under the same current stage to obtain the branch voltage average; use the branch voltage average to determine the branch voltage drop.

10. A testing system for the voltage of wiring harnesses in new energy vehicles, characterized in that, For performing the test method for the voltage of a new energy vehicle wiring harness as described in claim 1, the test system for the voltage of the new energy vehicle wiring harness includes: The no-load power-on test module is used to perform port calibration on the wire harness under test, connect to the power supply side and the load side, perform no-load power-on test, and output no-load deviation results. The terminal contact detection module is used to detect the terminal contact of the wire harness under test and determine the contact firmness if the no-load deviation result is higher than the maximum allowable deviation threshold. The dynamic voltage drop test module is used to perform dynamic voltage drop tests on the harness under test, determine the branch voltage drop difference, evaluate the harness uniformity, and identify abnormal branches based on the harness uniformity. The performance recording module is used to measure the insulation resistance of the conductors in abnormal branches to assess the risk of overheating; based on the risk of overheating and the degree of contact melting, it detects the degree of contact melting and records the electrical performance of the wire harness.

Images