A high voltage interlock detection method

Abstract

This invention relates to the field of battery technology, specifically disclosing a high-voltage interlock detection method. The high-voltage interlock detection method includes: S1. Connecting the signal input terminal of an EOL testing device to the low-voltage interface of the battery pack under test to form a low-voltage detection loop; S2. Starting the EOL testing device; if the EOL testing device detects continuity in the low-voltage detection loop, it determines that the high-voltage interlock of the battery pack under test is abnormal when the high voltage is not connected; otherwise, it determines that the high-voltage interlock of the battery pack under test is normal when the high voltage is not connected and proceeds to S3; S3. Connecting the high-voltage plug to the high-voltage interface of the battery pack under test and starting the EOL testing device; if the EOL testing device detects that the low-voltage detection loop is not continuous, it determines that the high-voltage interlock of the battery pack under test is abnormal when the high voltage is connected; otherwise, it determines that the high-voltage interlock of the battery pack under test is normal when the high voltage is connected. This invention only requires two continuity detection steps to complete the high-voltage interlock status judgment, simplifying the operation process and significantly improving detection efficiency.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a high-voltage interlock detection method. Background Technology

[0002] High Voltage Interlock (HVIL) is a crucial safety mechanism in the high-voltage system of new energy vehicles. Its core function is to monitor the connection status of relevant plugs and connectors in the high-voltage circuit, ensuring that the high-voltage power supply can be promptly cut off in the event of an unexpected disconnection, thus preventing safety risks such as electric shock. As the core power source of the high-voltage system in new energy vehicles, the reliability of the high-voltage interlock status of the power battery pack directly affects the overall vehicle safety performance. Therefore, the high-voltage interlock status must be rigorously tested during the end-of-line (EOL) stage of power battery pack production.

[0003] In existing technologies, high-voltage interlock detection is typically implemented by the VCU (Vehicle Controller Unit) or BMS (Battery Management System). When the high-voltage interlock detection function is integrated into the BMS, the EOL (End-of-Life) test equipment can directly determine whether a high-voltage interlock fault exists by reading the message signals sent by the BMS. However, in the design of some vehicle models, the high-voltage interlock detection function is handled by the VCU, rather than the BMS. In this case, the EOL test equipment cannot directly establish communication with the VCU to obtain high-voltage interlock status information, nor can it indirectly determine the fault by reading BMS messages—because the BMS itself does not have high-voltage interlock detection and signal output functions, rendering the traditional detection method relying on BMS messages ineffective.

[0004] To address these issues, existing solutions often involve establishing an additional test link for communication with the vehicle's VCU, or indirectly obtaining the VCU's high-voltage interlock test results using dedicated diagnostic equipment. However, these solutions have significant drawbacks: firstly, establishing a communication link with the VCU requires matching the vehicle's communication protocol, which is complex, incompatible, and unsuitable for batch EOL testing of different power battery pack models; secondly, dedicated diagnostic equipment is expensive and has a cumbersome testing process, resulting in low testing efficiency and failing to meet the production line's need for rapid off-line testing. Summary of the Invention

[0005] Based on this, the purpose of this invention is to provide a high-voltage interlock detection method that does not rely on VCU or BMS messages, thereby solving the technical problems of inconvenience, low efficiency, and poor compatibility caused by the inability of EOL testing equipment to directly read BMS messages when high-voltage interlock detection is handled by VCU.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a high-voltage interlock detection method, which includes the following steps: S1. Connect the signal input terminal of the EOL test equipment to the low-voltage interface of the battery pack under test to form a low-voltage detection circuit; S2. Start the EOL test equipment. If the EOL test equipment detects that the low-voltage detection circuit is conducting, it is determined that the high-voltage interlock of the battery pack under test is abnormal when the high voltage is not connected; otherwise, it is determined that the high-voltage interlock of the battery pack under test is normal when the high voltage is not connected and S3 is executed. S3. Connect the high-voltage plug to the high-voltage interface of the battery pack under test and start the EOL test equipment; if the EOL test equipment detects that the low-voltage detection circuit is not conducting, it is determined that the high-voltage interlock of the battery pack under test is abnormal under the high-voltage connection state; otherwise, it is determined that the high-voltage interlock of the battery pack under test is normal under the high-voltage connection state.

[0007] This invention differs from existing conventional detection methods that rely heavily on VCU / BMS messages or dedicated communication links. It innovatively proposes an external physical detection scheme with two states of high voltage disconnection / connection plus reverse conduction logic. This scheme does not require communication with the VCU or rely on BMS messages, fundamentally solving the problem of conventional methods failing in specific scenarios.

[0008] This invention requires only two continuity tests to determine the high-voltage interlock status. The operation process is simple and does not require complex debugging by professional technicians. The EOL testing equipment has a fast response time, and the testing time for a single battery pack can be controlled within 10 seconds. It is suitable for batch EOL testing scenarios on production lines and significantly improves testing efficiency.

[0009] The entire testing process of this invention is based on a low-voltage circuit, eliminating the need for a high-voltage power supply, thus avoiding safety risks during high-voltage testing and ensuring the safety of testing personnel.

[0010] As a further improvement to the above-described solution of the present invention, in step S1, connecting the signal input terminal of the EOL testing equipment to the low-voltage interface of the battery pack under test includes: A low-voltage test harness is provided, with low-voltage test plugs connected to both ends of the low-voltage test harness. Connect the low-voltage test plug at one end of the low-voltage test harness to the low-voltage interface of the battery pack under test, and connect the two low-voltage test plugs at the other end of the low-voltage test harness to the two signal input terminals of the EOL test equipment, respectively.

[0011] The low-voltage test plug, low-voltage test harness, and high-voltage plug required by this invention are all conventional battery pack test accessories, requiring no special diagnostic equipment or complex communication modules, which greatly reduces the cost of testing equipment; at the same time, the physical continuity detection method is less affected by external interference, and the test results are accurate and reliable with a low false positive rate.

[0012] As a further improvement to the above-mentioned solution of the present invention, all low-voltage test plugs are foolproof low-voltage test plugs. The connection between the low-voltage test harness and the low-voltage interface of the battery pack and the EOL test equipment is a foolproof connection, which can effectively avoid detection failures caused by incorrect insertion direction and ensure connection direction and contact stability.

[0013] As a further improvement to the above-described solution of the present invention, the resistance of the low-voltage test harness is ≤0.1Ω. The low-voltage test harness uses shielded wire to reduce the impact of external electromagnetic interference on the test results and ensure test accuracy.

[0014] As a further improvement to the above-mentioned solution of the present invention, in step S2, when the EOL testing equipment first detects the low-voltage detection circuit as conductive, after ensuring that all low-voltage test plugs are properly inserted and that the low-voltage test wiring harness is undamaged, the EOL testing equipment is restarted for testing. If the EOL testing equipment still detects the low-voltage detection circuit as conductive, it is determined that the battery pack under test is abnormally interlocked under the condition of high voltage disconnection. This eliminates the possibility of faults in the low-voltage detection circuit itself and ensures the accuracy of the test.

[0015] As a further improvement to the above-mentioned solution of the present invention, in step S3, when connecting the high-voltage plug to the high-voltage interface of the battery pack under test, it is ensured that the locking buckle of the high-voltage plug is closed to ensure the accuracy of the test conditions.

[0016] As a further improvement to the above-mentioned solution of the present invention, in step S3, when the EOL test equipment first detects that the low-voltage detection circuit is not conducting, after re-inserting the high-voltage plug, the EOL test equipment is restarted for detection. If the EOL test equipment still detects that the low-voltage detection circuit is not conducting, it is determined that the high-voltage interlock is abnormal in the high-voltage connection state of the battery pack under test.

[0017] As a further improvement to the above-mentioned solution of the present invention, the EOL testing equipment adopts a continuity tester.

[0018] As a further improvement to the above-mentioned solution of the present invention, the continuity detection accuracy of the EOL testing equipment is ≥1Ω and the detection response time is ≤50ms.

[0019] The EOL testing equipment uses a continuity tester with high sensitivity and a continuity detection accuracy of ≥1Ω, which can accurately identify the continuity status of tiny resistors; the detection response time is ≤50ms, ensuring rapid output of test results and improving batch testing efficiency.

[0020] As a further improvement to the above-mentioned solution of the present invention, after determining that the high-voltage interlock is abnormal when the battery pack under test is not connected to the high voltage, and after determining that the high-voltage interlock is abnormal when the battery pack under test is connected to the high voltage, the following steps are further performed: S4. Mark the battery packs that are found to be abnormal and proceed to the troubleshooting process. Attached Figure Description

[0021] Figure 1 A flowchart of a high-voltage interlock detection method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the construction principle of a low-voltage detection circuit in a high-voltage interlock detection method provided in an embodiment of the present invention.

[0022] Reference numerals: 1. Battery pack under test; 2. Low-voltage interface; 3. Low-voltage test plug; 4. Low-voltage test harness; 5. EOL test equipment; 6. High-voltage interface; 7. High-voltage plug; 8. High-voltage interlock loop inside the battery pack. Detailed Implementation

[0023] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] Reference Figure 1 This embodiment proposes a high-voltage interlock detection method, which includes the following steps: S1. Connect the signal input terminal of the EOL test equipment 5 to the low-voltage interface 2 of the battery pack under test 1 to form a low-voltage detection circuit.

[0026] Combination Figure 2 A low-voltage test harness 4 is provided, with a resistance ≤0.1Ω. Both ends of the low-voltage test harness 4 are connected to low-voltage test plugs 3. Connect one end of the low-voltage test plug 3 to the low-voltage interface 2 of the battery pack 1 under test. Connect the other end of the low-voltage test harness 4 to the two signal input terminals of the EOL testing equipment 5, thus forming a low-voltage detection circuit. After connection, check that the low-voltage test harness 4 is securely connected to prevent loosening.

[0027] All low-voltage test plugs 3 are foolproof low-voltage test plugs 3, which makes the connection between the low-voltage test harness 4 and the low-voltage interface 2 of the battery pack and the EOL test equipment 5 foolproof. This can effectively avoid test failures caused by incorrect insertion direction and ensure connection direction and contact stability. At the same time, the low-voltage test harness 4 uses shielded wire to reduce the impact of external electromagnetic interference on the test results and ensure test accuracy.

[0028] In this embodiment, the EOL testing device 5 adopts a continuity tester with high sensitivity continuity detection function, with a continuity detection accuracy ≥1Ω, which can accurately identify the continuity status of small resistors; the detection response time is ≤50ms, ensuring rapid output of detection results and improving batch testing efficiency.

[0029] S2. Start the EOL test device 5. If the EOL test device 5 detects that the low-voltage detection circuit is conducting, it is determined that the high-voltage interlock of the battery pack under test 1 is abnormal when the high voltage is not connected; otherwise, it is determined that the high-voltage interlock of the battery pack under test 1 is normal when the high voltage is not connected and S3 is executed.

[0030] According to the design logic of the high-voltage interlock, when the high-voltage plug 7 is not connected, the high-voltage interlock circuit should be in the open state, and the low-voltage detection circuit built in this embodiment should also be non-conductive. Therefore, if the EOL test device 5 detects that the low-voltage detection circuit is not conductive (the EOL test device 5 directly displays "non-conductive"), it is determined that the high-voltage interlock status of the battery pack is normal; if the low-voltage detection circuit is detected to be conductive (the EOL test device 5 directly displays "conductive"), it indicates that there is a short circuit or abnormal conduction fault in the high-voltage interlock circuit, and the high-voltage interlock status of the battery pack is determined to be abnormal.

[0031] In this step, when the EOL test equipment 5 first detects that the low-voltage detection circuit is conducting, after ensuring that all low-voltage test plugs 3 are inserted in place and that the low-voltage test harness 4 is not damaged, in order to rule out the fault of the low-voltage detection circuit itself, the EOL test equipment 5 is restarted for testing. If the EOL test equipment 5 still detects that the low-voltage detection circuit is conducting, it is determined that the high-voltage interlock is abnormal in the high-voltage disconnected state of the battery pack 1 under test.

[0032] S3. Connect the high-voltage plug 7 to the high-voltage interface 6 of the battery pack under test 1, and start the EOL test device 5; if the EOL test device 5 detects that the low-voltage detection circuit is not conducting, it is determined that the high-voltage interlock of the battery pack under test 1 is abnormal under the high-voltage connection state; otherwise, it is determined that the high-voltage interlock of the battery pack under test 1 is normal under the high-voltage connection state.

[0033] When connecting the high-voltage plug 7 to the high-voltage interface 6 of the battery pack 1 under test, ensure that the locking clip of the high-voltage plug 7 is closed to avoid loose connection that could lead to testing errors. After connecting the high-voltage plug 7, confirm that the connection is in place by visual inspection or mechanical inspection (e.g., observe whether the plug locking clip is fully closed) before performing a continuity test to ensure the accuracy of the testing conditions.

[0034] According to the design logic of the high-voltage interlock, when the high-voltage plug 7 is connected in place, the high-voltage interlock circuit should be in a closed state, and the low-voltage detection circuit built in this embodiment should also be conductive. Therefore, if the EOL test device 5 detects that the low-voltage detection circuit is conductive (the EOL test device 5 directly displays "conductive"), the high-voltage interlock status of the battery pack is determined to be normal. If the low-voltage detection circuit is not conductive (the EOL test device 5 directly displays "not conductive"), it indicates that there is an open circuit fault in the high-voltage interlock circuit, and the high-voltage interlock status of the battery pack is determined to be abnormal.

[0035] In this step, when the EOL test device 5 first detects that the low-voltage detection circuit is not conducting, after re-inserting the high-voltage plug 7, the EOL test device 5 is restarted for testing. If the EOL test device 5 still detects that the low-voltage detection circuit is not conducting, it is determined that the high-voltage interlock is abnormal in the high-voltage connection state of the battery pack 1 under test.

[0036] S4. Mark the battery packs that are found to be abnormal and proceed to the troubleshooting process.

[0037] In this embodiment, the detection time for a single battery pack is 8 seconds, the detection process is stable, and no misjudgments occur; when 100 battery packs of the same model are batch tested, the detection efficiency is improved by more than 60% compared with the existing solution that relies on VCU communication, and the cost of the detection equipment is reduced by 70%.

[0038] The testing method of the present invention is not only applicable to square power battery packs, but also to other types of new energy vehicle power battery packs such as cylindrical and pouch cells. It only requires replacing the low-voltage test plug 3 with the low-voltage interface 2 of the corresponding battery pack, and has wide applicability.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A high-voltage interlock detection method, characterized by, It includes the following steps: S1. Connect the signal input terminal of the EOL test equipment to the low-voltage interface of the battery pack under test to form a low-voltage detection circuit; S2. Start the EOL test equipment. If the EOL test equipment detects that the low-voltage detection circuit is conducting, it is determined that the high-voltage interlock of the battery pack under test is abnormal when the high voltage is not connected; otherwise, it is determined that the high-voltage interlock of the battery pack under test is normal when the high voltage is not connected and S3 is executed. S3. Connect the high-voltage plug to the high-voltage interface of the battery pack under test and start the EOL test equipment; if the EOL test equipment detects that the low-voltage detection circuit is not conducting, it is determined that the high-voltage interlock of the battery pack under test is abnormal under the high-voltage connection state; otherwise, it is determined that the high-voltage interlock of the battery pack under test is normal under the high-voltage connection state.

2. The method of claim 1, wherein, In step S1, connecting the signal input terminal of the EOL testing equipment to the low-voltage interface of the battery pack under test includes: A low-voltage test harness is provided, with low-voltage test plugs connected to both ends of the low-voltage test harness. Connect the low-voltage test plug at one end of the low-voltage test harness to the low-voltage interface of the battery pack under test, and connect the two low-voltage test plugs at the other end of the low-voltage test harness to the two signal input terminals of the EOL test equipment, respectively.

3. The method of claim 2, wherein, All low-voltage test plugs are foolproof low-voltage test plugs.

4. The method of claim 2, wherein, The resistance of the low-voltage test harness is ≤0.1Ω.

5. The method of claim 2, wherein, In step S2, when the EOL test equipment first detects that the low-voltage detection circuit is conducting, after ensuring that all low-voltage test plugs are inserted in place and that the low-voltage test harness is not damaged, the EOL test equipment is restarted for testing. If the EOL test equipment still detects that the low-voltage detection circuit is conducting, it is determined that the high-voltage interlock is abnormal in the high-voltage disconnected state of the battery pack under test.

6. The method of claim 1, wherein, In step S3, when connecting the high-voltage plug to the high-voltage interface of the battery pack under test, ensure that the locking buckle of the high-voltage plug is closed.

7. The method of claim 1, wherein, In step S3, when the EOL test equipment first detects that the low-voltage detection circuit is not conducting, after re-inserting the high-voltage plug, the EOL test equipment is restarted for testing. If the EOL test equipment still detects that the low-voltage detection circuit is not conducting, it is determined that the high-voltage interlock is abnormal in the high-voltage connection state of the battery pack under test.

8. The method of claim 1, wherein, The EOL testing equipment uses a continuity tester.

9. The method of claim 8, wherein, The continuity detection accuracy of the EOL testing equipment is ≥1Ω, and the detection response time is ≤50ms.

10. The method of claim 8, wherein, After determining that the high-voltage interlock is abnormal when the battery pack under test is not connected to high voltage, and after determining that the high-voltage interlock is abnormal when the battery pack under test is connected to high voltage, the following steps are also performed: S4. Mark the battery packs that are found to be abnormal and proceed to the troubleshooting process.

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