Battery system ntc abnormal fault diagnosis method and system

Abstract

The present application relates to the field of battery system NTC fault diagnosis, and discloses a battery system NTC abnormal fault diagnosis method and system, which identifies potential abnormal NTC; if the potential abnormal NTC has a temperature jump after being placed, or the temperature has abnormal fluctuation, or the temperature slowly rises, the corresponding potential abnormal NTC is marked as a fault NTC; if the battery pack corresponding to the marked fault NTC has thermal runaway, or the monitoring temperature is normal, the fault mark of the marked fault NTC is cancelled. The present application is based on the analysis of micro-short circuit abnormal phenomena caused by thermal runaway and condensation of temperature sensors, and comprehensively summarizes the abnormal performance of temperature sensors. It can solve the existing open circuit or open circuit fault, NTC micro-short circuit abnormal fault caused by condensation, and abnormal fault caused by the large temperature deviation of NTC itself, and avoid the false detection of high temperature or thermal runaway fault of the battery system caused thereby; at the same time, it also ensures that the real and rapid temperature rise caused by thermal runaway is accurately identified.

Description

Technical Field

[0001] This invention belongs to the field of NTC fault diagnosis of battery systems, and specifically relates to a method and system for diagnosing abnormal NTC faults in battery systems. Background Technology

[0002] As a core component of new energy vehicles, the battery system needs to constantly monitor information such as temperature, voltage, and current. Based on this information, it is crucial for early fault warnings, vehicle power limiting, and other fault prevention measures. Therefore, the reliability of temperature, voltage, and current data is paramount. NTC (Non-Temperature Traction Control) systems offer advantages such as low cost and simple peripheral design; therefore, they are commonly used in products currently on the market to obtain temperature readings.

[0003] NTC (Negative Temperature Coefficient) is an important component for detecting temperature in a battery system. It is equipped with an NTC temperature acquisition circuit to achieve the temperature acquisition function. When the NTC temperature acquisition circuit malfunctions, the acquired temperature value will be incorrect.

[0004] Therefore, if a fault in the NTC temperature acquisition circuit cannot be diagnosed in time, the product may perform incorrect operations based on the acquired erroneous values. When the battery system temperature is detected as high due to NTC abnormalities (such as short circuit, micro-short circuit, or excessively high NTC temperature), the battery system may falsely report a high-temperature fault, or even a thermal runaway fault, affecting customer experience and even driving safety.

[0005] Currently, the following two methods are mainly used for diagnosing NTC malfunctions in battery systems:

[0006] Method 1: When the NTC is disconnected, if the NTC resistance exceeds the maximum limit, it is diagnosed as an NTC open circuit fault.

[0007] Method 2: When the NTC is short-circuited, if the NTC resistance value exceeds the minimum limit, it is diagnosed as an NTC short-circuit fault.

[0008] While both methods can diagnose abnormal NTC faults in the battery system, they also have limitations: Method 1 can only diagnose open-circuit faults in the battery system's NTC, and cannot diagnose short-circuit faults; Method 2 can only diagnose complete short-circuit faults in the battery system's NTC, and cannot diagnose micro-short circuit faults caused by condensation, etc. (where the detected resistance does not exceed the minimum limit); Methods 1 and 2 can only diagnose open-circuit or short-circuit faults in the battery system's NTC, and cannot diagnose faults such as abnormally high NTC temperatures. Summary of the Invention

[0009] This invention provides a method and system for diagnosing NTC abnormalities in battery systems, which solves the problem of incomplete diagnosis of NTC abnormalities in the prior art.

[0010] To solve the above-mentioned technical problems, the technical solutions included in this invention and their corresponding beneficial effects are as follows:

[0011] This invention provides a scheme for diagnosing NTC abnormalities in a battery system, which identifies potential abnormal NTCs; if the temperature of a potential abnormal NTC changes abruptly after being left to stand, or fluctuates abnormally, or rises slowly, the corresponding potential abnormal NTC is marked as a faulty NTC; if the battery pack corresponding to the marked faulty NTC experiences thermal runaway, or the monitored temperature is normal, the faulty NTC is unmarked.

[0012] The beneficial effects of the above technical solution are as follows: This invention analyzes micro-short-circuit anomalies caused by thermal runaway and temperature sensor condensation, and comprehensively summarizes the patterns of abnormal temperature sensor behavior. When the NTC experiences a short circuit, open circuit, micro-short circuit due to condensation, or excessively high temperature within the NTC itself, the battery system temperature reading will be too high, resulting in temperature jumps after resting, abnormal temperature fluctuations, or a slow temperature rise. Therefore, this solution not only addresses existing open-circuit or short-circuit faults but also identifies micro-short-circuit anomalies caused by condensation and abnormal faults caused by excessively high NTC temperatures, preventing false high-temperature or thermal runaway faults in the battery system. It also ensures accurate identification of the true and rapid temperature rise caused by thermal runaway.

[0013] Furthermore, if the temperature difference between the highest temperature NTC and the second highest temperature NTC in a single battery pack is greater than a first set value and continues for a first set time, then the highest temperature NTC is identified as a potentially abnormal NTC.

[0014] Furthermore, if the temperature difference between the power-down temperature of a potentially abnormal NTC and its power-on temperature after a period of rest is greater than the second set value, it is identified as a temperature jump in the potentially abnormal NTC after resting.

[0015] Furthermore, if the temperature drop of a potential abnormal NTC is continuously detected to exceed a third set value within a second set time period, it is identified as an abnormal fluctuation in the temperature of the potential abnormal NTC.

[0016] Furthermore, if a potential abnormal NTC temperature rise is continuously detected within the third set time period, and the temperature rise rate is less than the fourth set value, then the potential abnormal NTC temperature is identified as slowly rising.

[0017] Furthermore, the thermal runaway occurs when one or more of the following conditions occur: a data acquisition disconnection fault occurs in the corresponding battery pack, or the voltage of a single battery cell in the corresponding battery pack drops by more than a fifth set value within a fourth set time period while the current is stable.

[0018] Furthermore, the normal monitoring temperature is defined as the temperature at which the marked faulty NTC is powered on for a set number of consecutive cycles: it is not the highest temperature, or the temperature difference between it and the second highest temperature is less than the first set value.

[0019] The present invention also provides a scheme for a battery system NTC abnormal fault diagnosis system, including a processor, the processor being used to execute program instructions to implement the battery system NTC abnormal fault diagnosis method as described above.

[0020] The beneficial effects of the above technical solution are as follows: This invention analyzes micro-short-circuit anomalies caused by thermal runaway and temperature sensor condensation, and comprehensively summarizes the patterns of abnormal temperature sensor behavior. When the NTC experiences a short circuit, open circuit, micro-short circuit due to condensation, or excessively high temperature within the NTC itself, the battery system temperature reading will be too high, resulting in temperature jumps after resting, abnormal temperature fluctuations, or a slow temperature rise. Therefore, this solution not only addresses existing open-circuit or short-circuit faults but also identifies micro-short-circuit anomalies caused by condensation and abnormal faults caused by excessively high NTC temperatures, preventing false high-temperature or thermal runaway faults in the battery system. It also ensures accurate identification of the true and rapid temperature rise caused by thermal runaway. Attached Figure Description

[0021] Figure 1 This is an abnormal NTC locking logic block diagram of the battery system NTC abnormal fault diagnosis method of the present invention;

[0022] Figure 2 This is a block diagram of the abnormal NTC unlocking logic of the battery system NTC abnormal fault diagnosis method of the present invention. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0024] Method Implementation Examples:

[0025] The basic concept of this invention is as follows: Existing technologies can only diagnose open circuits or open circuit faults in battery system NTCs. This invention analyzes micro-short circuit anomalies caused by thermal runaway and condensation on temperature sensors, and comprehensively summarizes the patterns of abnormal temperature sensor behavior. In addition to resolving existing open circuit faults, it can also identify micro-short circuit anomalies caused by condensation and other factors, as well as anomalies caused by excessively high NTC temperatures. Simultaneously, it ensures accurate identification of the true and rapid temperature rise caused by thermal runaway.

[0026] The steps of the battery system NTC fault diagnosis method of the present invention are as follows:

[0027] Step 1: Identify potential abnormal NTC probe points. If a potential abnormal probe point is identified, proceed to Step 2; otherwise, do not proceed.

[0028] Step 2: Determine whether the potential anomaly detection point meets the jump characteristic after being placed, that is, the abnormal NTC temperature jumps after being placed. If it meets the characteristic, the NTC at the detection point is considered to be abnormal and proceed to step 5; otherwise, proceed to step 3.

[0029] Step 3: Determine whether the potential anomaly detection point meets the abnormal fluctuation characteristics, that is, the abnormal NTC temperature fluctuates abnormally. If it does, it is considered that the NTC of the detection point is abnormal and proceed to step 5; otherwise, proceed to step 4.

[0030] Step 4: Determine whether the potential abnormal detection point meets the slow rise characteristic, that is, the abnormal NTC temperature rises slowly. If it meets the characteristic, it is considered that the NTC of the detection point is abnormal and proceed to step 5. Otherwise, repeat step 1 and re-diagnose.

[0031] Step 5: If any abnormal NTC fault point is identified in Step 2 / 3 / 4, the fault NTC point is latched, that is, the corresponding potential abnormal NTC is marked as a fault NTC, and the fault NTC point is processed according to actual needs.

[0032] The steps of the method for unlocking the fault NTC point after latching the battery system fault NTC point according to the present invention are as follows:

[0033] Step (1): If no potential abnormal NTC detection point is identified after three consecutive power-ups, unlock the faulty NTC point, that is, remove the fault mark from the marked faulty NTC; otherwise, proceed to step (2).

[0034] Step (2): When thermal runaway is possible, unlock the fault NTC point, that is, remove the fault mark of the marked fault NTC; otherwise, repeat step (1) or (2).

[0035] Specifically, such as Figure 1 The following is the method for diagnosing NTC malfunctions in the battery system:

[0036] First, potential abnormal NTC detection points are identified. If the temperature difference between the highest and second-highest NTC within a single battery pack is ≥8°C for more than 1 minute, the highest-temperature NTC is considered a potential abnormal point, and the battery system saves this potential abnormal NTC number. Here, 8°C is obtained based on thermal simulation. Under normal circumstances, the temperature difference between adjacent NTCs within a single battery pack should not exceed 8°C. If it exceeds 8°C, a potential abnormality is considered to exist, requiring further confirmation.

[0037] Once a potential abnormal NTC detection point is identified, it can be identified as a faulty NTC point if any of the following conditions are met.

[0038] 1. Temperature jump after being left idle: The NTC with potential faults has two consecutive power-on temperatures that are more than 3°C higher than the temperature at the time of the last power-off (power-off interval must be greater than 10 minutes);

[0039] 2. Abnormal temperature fluctuations exist: The NTC temperature dropped rapidly (more than 3°C within 20 seconds) on two consecutive occasions, indicating a potential fault.

[0040] 3. Slow temperature rise: The temperature rise rate of the NTC with potential faults is ≤2℃ / min for 20 consecutive minutes.

[0041] like Figure 2 The method for unlocking the fault NTC point after it has been latched in the battery system fault NTC point is as follows:

[0042] Once a faulty NTC is locked, the faulty NTC can be unlocked if any of the following conditions are met.

[0043] (1) The temperature of the fault NTC point locked after 3 consecutive power-on cycles: is not the highest temperature point, or the temperature difference with the second highest temperature point is less than 8℃.

[0044] In order to prevent thermal runaway from being incorrectly identified, the faulty NTC is also unlocked when any of the following situations that may be thermal runaway occur.

[0045] (2) A data acquisition disconnection fault occurred within the packet containing the locked fault NTC point;

[0046] (3) When the current is stable, the voltage of a single unit drops by more than 80mV within 500ms.

[0047] System Implementation Example:

[0048] The present invention provides a battery system NTC fault diagnosis system, comprising a processor for executing program instructions to implement the battery system NTC fault diagnosis method described in the method embodiment.

[0049] The specific embodiments of the present invention have been given above, but the present invention is not limited to the described embodiments. Under the concept given by the present invention, the technical means in the above embodiments can be changed, replaced, or modified in a way that is easy for those skilled in the art to conceive of, and the effect is basically the same as the corresponding technical means in the present invention, and the purpose of the invention is also basically the same. The technical solution formed in this way is a fine-tuning of the above embodiments, and such technical solution still falls within the protection scope of the present invention.

Claims

1. A method for diagnosing NTC abnormal faults in a battery system, characterized in that, Identify potential abnormal NTCs; if the temperature of a potential abnormal NTC jumps, fluctuates abnormally, or rises slowly after being left idle, mark the corresponding potential abnormal NTC as a faulty NTC; if the battery pack corresponding to the marked faulty NTC experiences thermal runaway, or the monitored temperature is normal, then remove the faulty mark from the marked faulty NTC.

2. The battery system NTC abnormality fault diagnosis method according to claim 1, characterized in that, If the temperature difference between the highest NTC and the second highest NTC in a single battery pack is greater than a first set value and continues for a first set time, then the highest NTC is identified as a potentially abnormal NTC.

3. The battery system NTC abnormality fault diagnosis method according to claim 2, characterized in that, If the temperature difference between the power-down temperature of a potentially abnormal NTC and its power-on temperature after a period of rest is greater than the second set value, it is identified as a temperature jump in the potentially abnormal NTC after resting.

4. The battery system NTC abnormality fault diagnosis method according to claim 2, characterized in that, If the temperature drop of a potential abnormal NTC is continuously detected to exceed the third set value within the second set time period, it is identified as an abnormal fluctuation in the temperature of the potential abnormal NTC.

5. The battery system NTC abnormality fault diagnosis method according to claim 2, characterized in that, If a potential abnormal NTC temperature rise is continuously detected within the third set time period, and the temperature rise rate is less than the fourth set value, then the potential abnormal NTC temperature is identified as slowly rising.

6. The battery system NTC abnormality fault diagnosis method according to claim 2, characterized in that, The thermal runaway occurs when one or more of the following conditions occur: a data acquisition disconnection fault occurs in the corresponding battery pack; or the voltage of a single battery cell in the corresponding battery pack drops by more than a fifth set value within a fourth set time period while the current is stable.

7. The battery system NTC abnormality fault diagnosis method according to claim 2, characterized in that, The normal monitoring temperature is: the temperature when the marked faulty NTC is powered on for a set number of consecutive times: it is not the highest temperature, or the temperature difference between it and the second highest temperature is less than the first set value.

8. A battery system NTC fault diagnosis system, characterized in that, Includes a processor, the processor being configured to execute program instructions to implement the battery system NTC fault diagnosis method as described in any one of claims 1-7.

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