A method for troubleshooting a power distribution unit contactor or relay

Abstract

This invention provides a method for troubleshooting and verifying anomalies in power distribution unit contactors or relays. The method includes the following steps: S1, connecting the high-voltage output terminal of a safety testing instrument to the power output terminal of the power distribution unit under test. By constructing a specific test connection architecture and troubleshooting logic, the method effectively solves the problems of detection blind spots and difficulty in fault location in traditional safety testing. This method uses a specific connection method to directly detect the insulation status between the main contacts and coils / auxiliary contacts of the switching device, thereby accurately identifying potential breakdown risks. Simultaneously, by disconnecting the external parallel circuit beforehand, test interference is eliminated; and by adopting a progressive sequence of "prioritizing insulation resistance testing and performing dielectric strength testing as needed," high voltage is applied to devices with serious defects, preventing breakdown.

Description

Technical Field

[0001] This invention relates to the field of electric vehicle charging technology, and more specifically, to a method for troubleshooting and verifying abnormalities in power distribution unit contactors or relays. Background Technology

[0002] In the field of power distribution unit production and maintenance for electric vehicle conductive charging systems, safety testing is a crucial step in ensuring the electrical safety of the equipment. Currently, the industry standard method for verifying the internal safety performance of power distribution units is to perform insulation resistance and dielectric strength tests between the power module output terminal (high voltage side) and the unit casing (protective ground PE) according to GB / T 18487.1-2023.

[0003] Specifically, existing technical solutions verify the insulation performance between the high-voltage output terminal and the protective earth (PE) casing by applying a specified test voltage, such as a 500V DC voltage for insulation resistance testing, or a standard-specified power frequency AC or DC test voltage for dielectric strength testing. However, this testing method has inherent limitations: it can only detect the safety distance and insulation condition between the high-voltage live circuit inside the power distribution unit and the casing, and cannot cover the insulation testing between components inside the unit.

[0004] Especially in contactors or relays within power distribution units, existing testing methods cannot detect the safety distance between their main contacts (high-voltage side) and the drive coil or feedback contacts (low-voltage side). In practical applications, insulation failure occurs between the main contacts and the drive coil inside the contactor or relay. Because existing testing methods do not use the drive coil or feedback contacts as test terminals, such internal insulation defects cannot be effectively detected, potentially leading to defective products with safety hazards entering the market and affecting the overall operational safety of the equipment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for troubleshooting and verifying abnormalities in power distribution unit contactors or relays to ensure the quality of production and maintenance processes and prevent abnormal units from entering the market, in order to address the shortcomings of the above-mentioned technical solutions.

[0006] This invention provides a method for troubleshooting and verifying abnormalities in power distribution unit contactors or relays, the method comprising the following steps: S1, connect the high voltage output terminal of the safety tester to the power output terminal of the power distribution unit under test, and simultaneously connect the test circuit terminal of the safety tester to the control terminal and feedback terminal of the internal switching device of the power distribution unit, wherein the internal switching device includes a contactor or a relay; control the safety tester to execute a preset safety test procedure between the power output terminal and the control terminal and feedback terminal; S2, read the insulation parameters output by the safety tester and determine whether the insulation parameters meet the preset safety judgment criteria; if it is determined to meet the criteria, confirm that the safety distance of the internal switching devices of the power distribution unit is normal; if it is determined not to meet the criteria, proceed to step S3. S3, group and isolate the power output terminals of the power distribution unit under test, perform the safety test procedure on each group of isolated terminals, compare the test results of each group of terminals with the preset safety judgment standard, retain the group of terminals whose test results do not meet the preset safety judgment standard, and repeat the group isolation and test procedure until the target switching device with abnormal safety distance is located.

[0007] In the power distribution unit contactor or relay anomaly troubleshooting and verification method described in this invention, the preset safety test procedure includes sequentially performing insulation resistance test and dielectric strength test.

[0008] In the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention; in step S1, the power output terminal is the power module output busbar of the power distribution unit; the control terminal and feedback terminal are the drive coil pin and feedback contact pin of the internal contactor or relay.

[0009] In the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention, the safety test procedure in step S1 is used to detect the insulation performance between the power module output busbar and the drive coil pin and feedback contact pin.

[0010] In the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention, the safety test process in step S1 includes a pre-processing step and a sequential test step. The pre-processing step is as follows: before performing the test, disconnect the power-consuming device in the power supply equipment that is electrically connected to the power distribution unit under test and is connected in parallel with the test circuit or forms a conductive path with the test circuit. The sequential test steps are as follows: Prioritize controlling the safety testing instrument to perform insulation resistance testing; If the insulation resistance test result meets the preset insulation resistance judgment standard, then the safety tester is controlled to continue performing the dielectric strength test. If the insulation resistance test result does not meet the preset insulation resistance judgment standard, the safety tester is controlled to skip the dielectric strength test and output insulation parameters that indicate non-compliance.

[0011] In the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention, the preset safety judgment criteria include insulation resistance judgment criteria and dielectric strength judgment criteria. The insulation resistance judgment standard is as follows: under the condition of applying a 500V DC voltage for 1 minute, the insulation resistance value should be greater than or equal to 10 MΩ; if the insulation resistance value is less than 10 MΩ, it is judged as an abnormal insulation performance and the safety distance does not meet the requirements. The dielectric strength determination criteria are as follows: under the condition of applying a power frequency AC voltage or DC voltage for 1 minute, there is no insulation breakdown, no flashover, and the leakage current is less than or equal to 10 mA; if insulation breakdown, flashover, or leakage current is greater than 10 mA, it is determined that the withstand voltage performance is abnormal and the safety distance does not meet the requirements.

[0012] In the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention, step S3 includes the following steps: S31, divide the power output terminals within the current test range into a first group of terminals and a second group of terminals; S32, Perform the insulation resistance test on the first group of terminals and the second group of terminals respectively; S33, compare the test results of the first group of terminals and the second group of terminals. If the test result of the first group of terminals is abnormal and the test result of the second group of terminals is normal, then the first group of terminals is determined as a new test range; if the test result of the second group of terminals is abnormal and the test result of the first group of terminals is normal, then the second group of terminals is determined as a new test range. S34. Repeat steps S31 to S33 until the test range is narrowed down to a single contactor or relay, thereby locating the target switching device with the abnormal safety distance.

[0013] The power distribution unit contactor or relay anomaly troubleshooting and verification method of this invention effectively solves the problems of detection blind spots and difficulty in fault location in traditional safety testing by constructing a specific test connection architecture and troubleshooting logic. This method uses a specific connection method to directly detect the insulation status between the main contacts and coils / auxiliary contacts of the switching device, thereby accurately identifying potential breakdown risks. Simultaneously, by disconnecting the external parallel circuit beforehand, test interference is eliminated; and a progressive sequence of "prioritizing insulation resistance testing and performing dielectric strength testing as needed" is adopted to avoid applying high voltage to devices with serious defects, which could lead to breakdown. Furthermore, this method introduces a binary grouping iterative troubleshooting mechanism. When the initial test fails, group isolation and comparative testing are used to lock down the abnormal group and iterate repeatedly until the faulty device is located. This strategy eliminates the need for disassembly, significantly shortening the fault troubleshooting time. Combined with preset safety judgment standards, this method eliminates human judgment errors and ensures the consistency of test results. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating an embodiment of the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention; Figure 2 This is a schematic diagram of the actual market application topology to which the power distribution unit contactor or relay anomaly troubleshooting and verification method of the present invention is applicable. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0016] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0017] like Figure 1 As shown, Figure 1This is a flowchart illustrating an embodiment of a method for troubleshooting and verifying anomalies in a power distribution unit contactor or relay according to the present invention. The method includes the following steps: In step S1, the high-voltage output terminal of the safety tester is connected to the power output terminal of the power distribution unit under test, and the test circuit terminal of the safety tester is connected to the control terminal and feedback terminal of the internal switching device of the power distribution unit. The internal switching device includes a contactor or a relay. The safety tester is controlled to perform a preset safety test procedure between the power output terminal and the control terminal and feedback terminal. In step S2, the insulation parameters output by the safety tester are read, and it is determined whether the insulation parameters meet the preset safety judgment criteria. If it is determined that they meet the criteria, it is confirmed that the safety distance of the internal switching devices of the power distribution unit is normal. If it is determined that they do not meet the criteria, step S3 is executed. In step S3, the power output terminals of the power distribution unit under test are grouped and isolated. The safety test procedure is performed on each group of isolated terminals. The test results of each group of terminals are compared with the preset safety judgment standard. The group of terminals whose test results do not meet the preset safety judgment standard is retained. The grouping isolation and test procedure is repeated until the target switching device with abnormal safety distance is located.

[0018] In one embodiment, the preset safety testing procedure includes sequentially performing an insulation resistance test and a dielectric strength test.

[0019] In one embodiment, the power output terminal in step S1 is the power module output busbar of the power distribution unit; the control terminal and feedback terminal are the drive coil pin and feedback contact pin of the internal contactor or relay.

[0020] In one embodiment, the safety test procedure in step S1 is used to detect the insulation performance between the power module output busbar and the drive coil pin and feedback contact pin.

[0021] In one embodiment, the safety testing process in step S1 includes a pre-processing step and a sequential testing step; The pre-processing step is as follows: before performing the test, disconnect the power-consuming device in the power supply equipment that is electrically connected to the power distribution unit under test and is connected in parallel with the test circuit or forms a conductive path with the test circuit. The sequential test steps are as follows: Prioritize controlling the safety testing instrument to perform insulation resistance testing; If the insulation resistance test result meets the preset insulation resistance judgment standard, then the safety tester is controlled to continue performing the dielectric strength test. If the insulation resistance test result does not meet the preset insulation resistance judgment standard, the safety tester is controlled to skip the dielectric strength test and output insulation parameters that indicate non-compliance.

[0022] In one embodiment, the preset safety standard includes an insulation resistance standard and a dielectric strength standard; The insulation resistance judgment standard is as follows: under the condition of applying a 500V DC voltage for 1 minute, the insulation resistance value should be greater than or equal to 10 MΩ; if the insulation resistance value is less than 10 MΩ, it is judged as an abnormal insulation performance and the safety distance does not meet the requirements. The dielectric strength determination criteria are as follows: under the condition of applying a power frequency AC voltage or DC voltage for 1 minute, there is no insulation breakdown, no flashover, and the leakage current is less than or equal to 10 mA; if insulation breakdown, flashover, or leakage current is greater than 10 mA, it is determined that the withstand voltage performance is abnormal and the safety distance does not meet the requirements.

[0023] In one embodiment, step S3 includes the following steps: In step S31, the power output terminals within the current test range are divided into a first group of terminals and a second group of terminals. In step S32, the insulation resistance test is performed on the first group of terminals and the second group of terminals respectively; In step S33, the test results of the first group of terminals and the second group of terminals are compared. If the test result of the first group of terminals is abnormal and the test result of the second group of terminals is normal, then the first group of terminals is determined as a new test range; if the test result of the second group of terminals is abnormal and the test result of the first group of terminals is normal, then the second group of terminals is determined as a new test range. In step S34, steps S31 to S33 are repeated until the range to be tested is reduced to a single contactor or relay, thereby locating the target switching device with the abnormal safety distance.

[0024] This invention constructs a safety testing connection architecture that connects the high-voltage output of the safety tester to the power output busbar of the power distribution unit, and connects the test circuit to the drive coil pins and feedback contact pins of the internal switching devices (contactors or relays). This connection method establishes a test path with the "power circuit" and the "control / feedback circuit" as the two poles, enabling direct detection of the insulation status of the main contacts of the internal switching devices to the coils and auxiliary contacts. Through this test path, potential breakdown risks caused by abnormal internal device structures, insufficient creepage distances, or aging insulation media can be identified, improving the quality screening capability of the power distribution unit and reducing the risk of product failure due to insufficient safety distances of internal devices.

[0025] Furthermore, this invention controls the testing process by setting up pre-processing steps and sequential testing logic. Before executing the test, external power-consuming devices connected in parallel with the test circuit or forming a conductive path are disconnected, eliminating interference from external parallel circuits on the insulation test results and ensuring that the collected insulation parameters reflect the state of the internal switching devices. Based on this, a sequence of "insulation resistance testing first, dielectric strength testing as needed" is executed: first, insulation resistance testing is used for preliminary screening to identify defects such as insulation dampness, dirt, or overall aging; if the insulation resistance meets the preset standard (e.g., ≥10MΩ), dielectric strength testing is performed. This testing strategy prevents the application of high voltage to devices with serious insulation defects, avoiding device breakdown or expansion of the fault range due to withstand voltage testing, and improving troubleshooting efficiency and safety while protecting the integrity of the device under test.

[0026] To pinpoint the fault location, this invention introduces a binary search grouping and iterative troubleshooting mechanism. After an initial test determines the fault to be non-compliant, the power output terminals within the current test range are divided into two groups using a binary search method, and insulation resistance tests are performed on each group separately. By comparing the test results, the abnormal area is identified. This strategy transforms the internal circuit network into a step-by-step troubleshooting structure. By repeatedly performing the steps of grouping, testing, comparing, and range locking, technicians narrow down the fault investigation range in each iteration until the target switching device causing the safety distance abnormality is identified. This reduces the time cost of fault troubleshooting, avoids the scrapping of entire modules due to the inability to locate the specific fault point, and reduces the difficulty of production line maintenance and after-sales repair costs.

[0027] Furthermore, this method, combined with pre-set safety regulations, enables management from qualitative testing to quantitative assessment. The synergistic application of insulation resistance assessment standards (e.g., 500V DC / 1min, ≥10MΩ) and dielectric strength assessment standards (e.g., power frequency voltage / 1min, no breakdown flashover and leakage current ≤10mA) forms a "preliminary screening + limit verification" assurance mechanism. Standardized assessment parameters eliminate errors from manual experience-based judgment, ensuring consistency of test results across different batches and personnel. Real-time monitoring of leakage current can detect weak conductive defects in the insulating medium under high voltage (e.g., partial discharge, micro-cracks), ensuring that even without obvious breakdown, weak points in the insulation can be identified, providing evaluation criteria for mass production quality control and after-sales fault analysis of power distribution units.

[0028] As shown in Figure 2, this power distribution unit includes multiple charging ports (e.g., 1 charging port M1, 2 charging ports M3, 4 charging ports M7, 6 charging ports M13, 9 charging ports M4, 11 charging ports M8, 13 charging ports M16, 12 charging ports M10, 10 charging ports M6, 14 charging ports M15, etc.) and several switching devices (labeled as KM in the figure, e.g., 2-KM1, 2-KM2...2-KM17). In actual circuit connections, these switching devices (contactors or relays) form a complex matrix or mesh connection to achieve on / off control and power distribution between different charging ports and the power module.

[0029] In a specific application scenario of this invention, the aforementioned power distribution unit has been operating for an extended period in a real-world market environment. Under prolonged charge-discharge cycles and specific complex operating conditions (such as frequent high-current switching, grid fluctuations, or environmental aging), some contactors or relays (KM) may experience physical characteristic degradation. Specifically, the core problem addressed by this invention is the deterioration of the insulation performance between the main contacts of the switching device and its drive coil or auxiliary feedback contacts, leading to abnormal safety distances. This abnormality may manifest as reduced insulation resistance or a potential breakdown risk; if not addressed promptly, it can easily cause a safety accident where high voltage enters the low-voltage control circuit.

[0030] In response to the faults that have occurred in the actual operation of the market, this invention provides a fault diagnosis scheme for power distribution units. When an insulation abnormality or failure to pass a safety test is detected in the system, there is no need to physically disassemble the complex topology shown in the figure. Instead, the test sequence of "prioritizing insulation resistance testing and performing dielectric strength testing as needed" described above is directly applied, combined with the "binary grouping iterative troubleshooting mechanism".

[0031] In practice, maintenance personnel or automated testing systems logically group the power output terminals or internal contactor groups of the power distribution unit under test according to the topology shown in the diagram. For example, the contactors in the diagram are first divided into left and right halves (or into input and output groups based on electrical connection paths), and safety testing procedures are performed separately for each group. By comparing the test data of each group with preset safety judgment standards, the abnormal group is quickly identified, and this grouping and isolation process is repeated iteratively until the specific faulty contactor or relay is precisely located (e.g., locked to a specific 2-KMx). In practical market applications, this solution significantly improves the efficiency and accuracy of troubleshooting such hidden safety faults.

[0032] Specific examples demonstrate that a power distribution unit returned from the market, with no obvious external faults and passing the standard GB / T 18487.1 tests for ground (PE) insulation and withstand voltage, was found to have an abnormal safety distance between the main contact and feedback contact when the troubleshooting method of this invention (testing the contactor contacts and coil) was used in conjunction with the binary search method. Disassembly confirmed that this contactor's internal structure was abnormal, leading to insufficient safety distance. This hidden defect could only be detected using the specialized testing method for internal components proposed in this invention. Therefore, the troubleshooting and verification method proposed in this invention can cover internal component safety distance abnormalities that traditional testing methods cannot reach, reducing the risk of defective products entering the market and enhancing the operational safety of equipment under high voltage and high current conditions.

[0033] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0034] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes 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 ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0035] Therefore, the above description is only a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for troubleshooting and verifying abnormalities in a power distribution unit contactor or relay, characterized in that, The method includes the following steps: S1, connect the high voltage output terminal of the safety tester to the power output terminal of the power distribution unit under test, and simultaneously connect the test circuit terminal of the safety tester to the control terminal and feedback terminal of the internal switching device of the power distribution unit, wherein the internal switching device includes a contactor or a relay; control the safety tester to execute a preset safety test procedure between the power output terminal and the control terminal and feedback terminal; S2, read the insulation parameters output by the safety tester and determine whether the insulation parameters meet the preset safety judgment criteria; if it is determined to meet the criteria, confirm that the safety distance of the internal switching devices of the power distribution unit is normal; if it is determined not to meet the criteria, proceed to step S3. S3, group and isolate the power output terminals of the power distribution unit under test, perform the safety test procedure on each group of isolated terminals, compare the test results of each group of terminals with the preset safety judgment standard, retain the group of terminals whose test results do not meet the preset safety judgment standard, and repeat the group isolation and test procedure until the target switching device with abnormal safety distance is located.

2. The method for troubleshooting and verifying abnormalities in the power distribution unit contactor or relay according to claim 1, characterized in that, The preset safety testing procedure includes sequentially performing insulation resistance testing and dielectric strength testing.

3. The method for troubleshooting and verifying abnormalities in the power distribution unit contactor or relay according to claim 2, characterized in that, In step S1, the power output terminal is the power module output busbar of the power distribution unit; the control terminal and feedback terminal are the drive coil pin and feedback contact pin of the internal contactor or relay.

4. The method for troubleshooting and verifying abnormalities in the power distribution unit contactor or relay according to claim 3, characterized in that, In step S1, the safety test procedure is used to detect the insulation performance between the power module output busbar and the drive coil pin and feedback contact pin.

5. The method for troubleshooting and verifying abnormalities in the power distribution unit contactor or relay according to claim 4, characterized in that, The safety testing process in step S1 includes a pre-processing step and a sequential testing step; The pre-processing step is as follows: before performing the test, disconnect the power-consuming device in the power supply equipment that is electrically connected to the power distribution unit under test and is connected in parallel with the test circuit or forms a conductive path with the test circuit. The sequential test steps are as follows: Prioritize controlling the safety testing instrument to perform insulation resistance testing; If the insulation resistance test result meets the preset insulation resistance judgment standard, then the safety tester is controlled to continue performing the dielectric strength test. If the insulation resistance test result does not meet the preset insulation resistance judgment standard, the safety tester is controlled to skip the dielectric strength test and output insulation parameters that indicate non-compliance.

6. The method for troubleshooting and verifying abnormalities in the power distribution unit contactor or relay according to claim 2, characterized in that, The preset safety regulations include insulation resistance and dielectric strength standards. The insulation resistance judgment standard is as follows: under the condition of applying a 500V DC voltage for 1 minute, the insulation resistance value should be greater than or equal to 10 MΩ; if the insulation resistance value is less than 10 MΩ, it is judged as an abnormal insulation performance and the safety distance does not meet the requirements. The dielectric strength determination criterion is: under the condition of applying a power frequency AC voltage or DC voltage for 1 minute, there is no insulation breakdown, no flashover, and the leakage current is less than or equal to 10 mA. If insulation breakdown, flashover, or leakage current greater than 10 mA occurs, it is determined to be an abnormal withstand voltage performance and the safety distance requirement is not met.

7. The modulation method according to claim 4, characterized in that, Step S3 includes the following steps: S31, divide the power output terminals within the current test range into a first group of terminals and a second group of terminals; S32, Perform the insulation resistance test on the first group of terminals and the second group of terminals respectively; S33, compare the test results of the first group of terminals and the second group of terminals. If the test result of the first group of terminals is abnormal and the test result of the second group of terminals is normal, then the first group of terminals is determined as a new test range; if the test result of the second group of terminals is abnormal and the test result of the first group of terminals is normal, then the second group of terminals is determined as a new test range. S34. Repeat steps S31 to S33 until the test range is narrowed down to a single contactor or relay, thereby locating the target switching device with the abnormal safety distance.

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