Thermal runaway early warning method for energy storage system

Abstract

The invention discloses an early warning method for thermal runaway of an energy storage system. The early warning method comprises the following steps that a detection unit is installed on each unit of the energy storage system and connected with an upper computer; setting data processing and early warning judgment related parameters; acquiring electrochemical impedance spectroscopy data of the energy storage system in real time; performing optimization processing on the electrochemical impedance spectroscopy data by using a data filtering algorithm; and calculating an impedance change rate based on the electrochemical impedance spectrum data, and if the impedance change rate is greater than a set threshold value, sending an alarm signal and taking emergency measures. According to the thermal runaway early warning method of the energy storage system, the abnormal state of the battery, especially the early signal of thermal runaway, can be sensitively monitored through real part and phase angle changes under different frequencies, and higher-precision early warning is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of runaway warning of energy storage systems, and relates to a thermal runaway warning method for energy storage systems. Background Art

[0002] With the continuous expansion of battery applications, especially the widespread use of batteries in electric vehicles, energy storage systems, and portable electronic devices, battery safety issues are particularly important. Battery thermal runaway is one of the main causes of battery accidents, which may cause the battery to overheat, swell, catch fire, or even explode. Existing battery monitoring technology mainly determines whether the battery's operating status is normal based on external parameters such as battery temperature, charge and discharge voltage, and current. The disadvantage of this technology is that it cannot obtain internal battery safety information and often cannot provide sufficiently timely and accurate early warning information before the battery thermal runaway occurs. Therefore, how to detect abnormal conditions inside the battery in advance, especially the risk of thermal runaway, has become a major challenge in battery safety management. Inside the battery, changes in electrochemical reactions will cause changes in battery impedance. By performing online impedance spectroscopy detection and analysis of these electrochemical characteristics, abnormal changes in the battery can be more sensitively captured and the risk of thermal runaway can be identified in advance.

[0003] In summary, the existing technology has the problem of difficulty in accurately warning of thermal runaway of energy storage systems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for early warning of thermal runaway of an energy storage system, which solves the problem in the prior art that it is difficult to accurately early warn of thermal runaway of an energy storage system.

[0005] The technical solution adopted by the present invention is a thermal runaway early warning method for an energy storage system, comprising the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than the set threshold, issue an alarm signal and take emergency measures. If the impedance change rate is not greater than the set threshold, repeat steps 3 to 5.

[0006] The present invention is also characterized in that: Step 1 includes: installing a detection chip on each battery cell of the energy storage system, and several detection chips are communicatively connected to the host computer through the battery cell connection system.

[0007] The electrochemical impedance spectroscopy data includes the real part of impedance, the imaginary part of impedance, the impedance amplitude, and the impedance phase.

[0008] The data filtering algorithm includes: establishing a data buffer and storing several groups of data, averaging the data in the buffer, and recording the average value as Zavg; each time new impedance data is collected, it is compared with the average value of the buffer. If the new impedance data is greater than Zavg+5, the new impedance data is recorded as Zavg+5 and placed in the buffer. If the new impedance data is less than Zavg-5, the new impedance data is recorded as Zavg-5 and placed in the buffer.

[0009] Step five includes: calculating the real-time impedance change rate based on the electrochemical impedance spectroscopy data, and repeating steps three to five if the real-time impedance change rate is not greater than a set threshold.

[0010] Step five includes: The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, an alarm signal is issued and the real-time impedance real part is recorded as the first impedance real part. The real-time impedance real part is not greater than the first impedance real part within the subsequent set time. After eliminating the first impedance real part, repeat steps 3 to 5.

[0011] Step five includes: calculating the real-time impedance real part change rate based on the electrochemical impedance spectroscopy data; if the real-time impedance real part change rate is greater than a set threshold for the first time, issuing an alarm signal and recording the real-time impedance real part as the first impedance real part; if the real-time impedance real part is greater than the first impedance real part within a subsequent set time, issuing an alarm signal and cutting off the energy storage system circuit to prevent thermal runaway.

[0012] The calculation formula of the real-time impedance real part change rate is as follows: , Where k represents the rate of change of the real part of the impedance, Zr1 represents the real part of the impedance T minutes ago, Zr2 represents the real part of the impedance at present, and T represents the detection period.

[0013] The beneficial effects of the present invention are: the present invention can sensitively monitor the abnormal state of the battery, especially the early signals of thermal runaway, through the changes in the real part and phase angle at different frequencies, and provide higher-precision early warning; compared with traditional temperature and voltage monitoring methods, the present invention can identify abnormalities early through the electrochemical impedance characteristics of the battery, generate thermal runaway alarm information in advance, and help take timely measures to avoid serious accidents; this method is applicable to different types of batteries, especially high-energy-density batteries such as lithium batteries, and is widely applicable to electric vehicles, energy storage systems, portable electronic devices and other fields; by real-time monitoring of the electrochemical impedance characteristics of the battery at different frequencies, abnormal fluctuations in the battery operation process can be accurately detected, thereby effectively reducing safety risks such as thermal runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the thermal runaway early warning method for an energy storage system according to the present invention; Figure 2 1 is a schematic diagram of hardware connections in an embodiment of the present invention; Figure 3 This is a graph of thermal runaway experimental data in an embodiment of the present invention; Figure 4 Schematic diagram of the change of the real part of impedance and the rate of change of the real part in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Thermal runaway warning methods for energy storage systems, such as Figure 1 As shown, the following steps are included: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; A detection chip is installed on each battery cell of the energy storage system, and several detection chips are connected to the host computer through the battery cell connection system.

[0017] Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; The electrochemical impedance spectroscopy data includes the real part of impedance, the imaginary part of impedance, the impedance amplitude, and the impedance phase.

[0018] Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; The data filtering algorithm includes: establishing a data buffer and storing several groups of data, averaging the data in the buffer, and recording the average value as Zavg; each time new impedance data is collected, it is compared with the average value of the buffer. If the new impedance data is greater than Zavg+5, the new impedance data is recorded as Zavg+5 and placed in the buffer. If the new impedance data is less than Zavg-5, the new impedance data is recorded as Zavg-5 and placed in the buffer.

[0019] Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than the set threshold, issue an alarm signal and take emergency measures. If the impedance change rate is not greater than the set threshold, repeat steps 3 to 5.

[0020] The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate is not greater than the set threshold, steps 3 to 5 are repeated.

[0021] The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, an alarm signal is issued and the real-time impedance real part is recorded as the first impedance real part. The real-time impedance real part is not greater than the first impedance real part within the subsequent set time. After eliminating the first impedance real part, repeat steps 3 to 5.

[0022] The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, an alarm signal is issued and the real-time impedance real part is recorded as the first impedance real part. If the real-time impedance real part is greater than the first impedance real part within the subsequent set time, an alarm signal is issued and the energy storage system circuit is cut off to prevent thermal runaway.

[0023] The calculation formula of the real-time impedance real part change rate is as follows: , Where k represents the rate of change of the real part of the impedance, Zr1 represents the real part of the impedance T minutes ago, Zr2 represents the real part of the impedance at present, and T represents the detection period.

[0024] In the data filtering algorithm of the present invention, the data is input and output each time using the first-in-first-out method. This filtering method can not only take the average, but also reduce the fluctuation of the impedance data, and effectively avoid the distortion of the results caused by the sudden change of the impedance data. The present invention uses this filtering algorithm to optimize the real part, imaginary part, phase and amplitude of the impedance.

[0025] This invention utilizes online impedance spectroscopy technology, which efficiently and accurately assesses the internal state of an energy storage system by monitoring changes in electrochemical impedance in real time. This technology is unique in its non-destructive, real-time detection method, enabling continuous acquisition of impedance data from energy storage units without impacting system operation, thereby providing more comprehensive feedback on the operating status of the energy storage device. This online detection technology overcomes the limitations of traditional monitoring methods and significantly improves the safety and reliability of energy storage systems.

[0026] Traditional energy storage system monitoring relies heavily on single parameters such as temperature and pressure, but these indicators cannot fully reflect the health of the energy storage unit. The present invention introduces electrochemical impedance data as a criterion for thermal runaway judgment, providing a new monitoring dimension for energy storage systems. Changes in electrochemical impedance reflect multiple key factors such as the internal chemical reaction, ion conduction, and electron transport of the battery, and can more accurately reflect whether the energy storage system has a potential risk of thermal runaway. This innovative introduction enables the present invention to have higher accuracy and real-time performance in safety monitoring and early warning of energy storage systems.

[0027] The present invention establishes a data cache to store and average impedance data, thereby reducing the interference of data fluctuations and mutations on the early warning system. When new impedance data is collected, it is compared with the average value of the cache. If it exceeds the set threshold, the data will be restricted and updated to the cache to ensure data stability. Combined with this unique filtering algorithm, the early warning system can analyze the changing trends of impedance data in real time, identify potential thermal runaway risks, and take preventive measures in advance. This method effectively improves the safety of the energy storage system, prevents catastrophic accidents caused by thermal runaway, and ensures the long-term stable operation of the energy storage equipment.

[0028] By comprehensively analyzing impedance data trends and incorporating advanced algorithmic models, this early warning method can identify potential risks before thermal runaway occurs, allowing preventive measures to be taken in advance. This approach will significantly improve the safety of energy storage systems, prevent catastrophic accidents caused by thermal runaway, and ensure the long-term stable operation of energy storage equipment.

[0029] Example 1 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than a set threshold, issue an alarm signal and take emergency measures.

[0030] Example 2 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is not greater than the set threshold, repeat steps 3 to 5.

[0031] Example 3 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; A detection chip is installed on each battery cell of the energy storage system, and several detection chips are connected to the host computer through the battery cell connection system.

[0032] Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; The electrochemical impedance spectroscopy data includes the real part of impedance, the imaginary part of impedance, the impedance amplitude, and the impedance phase.

[0033] Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than a set threshold, issue an alarm signal and take emergency measures.

[0034] Example 4 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; The data filtering algorithm includes: establishing a data buffer and storing several groups of data, averaging the data in the buffer, and recording the average value as Zavg; each time new impedance data is collected, it is compared with the average value of the buffer. If the new impedance data is greater than Zavg+5, the new impedance data is recorded as Zavg+5 and placed in the buffer. If the new impedance data is less than Zavg-5, the new impedance data is recorded as Zavg-5 and placed in the buffer.

[0035] Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is not greater than the set threshold, repeat steps 3 to 5.

[0036] Example 5 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the real-time impedance change rate based on the electrochemical impedance spectroscopy data. If the real-time impedance change rate is not greater than the set threshold, repeat steps 3 to 5.

[0037] The calculation formula of the real-time impedance real part change rate is as follows: , Where k represents the rate of change of the real part of the impedance, Zr1 represents the real part of the impedance T minutes ago, Zr2 represents the real part of the impedance at present, and T represents the detection period.

[0038] Example 6 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5. Calculate the real-time impedance real part change rate based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, issue an alarm signal and record the real-time impedance real part as the first impedance real part. If the real-time impedance real part is not greater than the first impedance real part within the subsequent set time, repeat steps 3 to 5 after eliminating the first impedance real part.

[0039] Example 7 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than a set threshold, issue an alarm signal and take emergency measures. The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, an alarm signal is issued and the real-time impedance real part is recorded as the first impedance real part. If the real-time impedance real part is greater than the first impedance real part within the subsequent set time, an alarm signal is issued and the energy storage system circuit is cut off to prevent thermal runaway.

[0040] Example 8 This embodiment proposes a thermal runaway early warning method for an energy storage system, including the following steps: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than a set threshold, issue an alarm signal and take emergency measures. The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, an alarm signal is issued and the real-time impedance real part is recorded as the first impedance real part. If the real-time impedance real part is greater than the first impedance real part within the subsequent set time, an alarm signal is issued and the energy storage system circuit is cut off to prevent thermal runaway.

[0041] The calculation formula of the real-time impedance real part change rate is as follows: , Where k represents the rate of change of the real part of the impedance, Zr1 represents the real part of the impedance T minutes ago, Zr2 represents the real part of the impedance at present, and T represents the detection period.

[0042] like Figure 2 As shown, in the embodiment of the present invention, a CCS (Cells Contact System) is used to integrate and collect battery information. An AFE chip (Analog Front End) with voltage, temperature, and impedance acquisition functions is connected to each battery cell. The advantage of this method over traditional methods is that each battery cell unit has an impedance test function, thereby performing all-round detection and protection of the operating status of the entire energy storage system.

[0043] like Figure 3 As shown, the battery cell was charged from 0% SOC (State of Charge) until thermal runaway occurred. During this period, our experimental platform was used to collect voltage, temperature, and impedance data. The impedance frequency was set to a fixed frequency, and the cell was subjected to a PWM wave scan using chip excitation to collect and calculate the real and imaginary impedance parts, amplitude, and phase. Observing the experimental data graph, it can be seen that before thermal runaway occurs, the real part of the impedance drops sharply, which is a warning sign before thermal runaway occurs. When the real part of the impedance changes dramatically, timely disconnecting the circuit can effectively prevent thermal runaway, so this is defined as the thermal runaway protection stage, that is, protection before 11.57.

[0044] like Figure 4 As shown in the figure, the changes of the real part of the impedance and the rate of change of the real part are further analyzed, and the moment when thermal runaway can be detected is defined as the thermal runaway detection point, and the thermal runaway irreversible point is also defined; Over a three-minute period, the real impedance change rate exceeds a threshold, typically set at 5. Thermal runaway can be avoided by promptly disconnecting the circuit between the thermal runaway detection point and the point of no return. At the software level, the thermal runaway criterion is defined as an absolute value of the real impedance change rate greater than 5. The host computer calculates the real impedance change rate for the preceding three minutes every minute, effectively updating the real impedance change rate once a minute. The rate of change curve shown in the figure is derived using this method. Between the thermal runaway detection point and the point of no return, four data points can be detected as abnormal, providing a four-minute margin for shutdown operations, ensuring the reliability of this method.

[0045] When the real part change rate is detected to be greater than 5, in order to prevent the relay from not operating, an inflection point judgment function is added here. When the real part change rate is greater than 5, the current real part value is saved. If the real part data is greater than this point later, an alarm signal is issued and the circuit is cut off to prevent thermal runaway.

Claims

1. A thermal runaway early warning method for an energy storage system, characterized in that: The following steps are involved: Step 1: Install a detection unit in each unit of the energy storage system and connect it to the host computer; Step 2: Set parameters related to data processing and early warning judgment; Step 3: Acquire electrochemical impedance spectroscopy data of the energy storage system in real time; Step 4: Use data filtering algorithm to optimize the electrochemical impedance spectroscopy data; Step 5: Calculate the impedance change rate based on the electrochemical impedance spectroscopy data. If the impedance change rate is greater than the set threshold, issue an alarm signal and take emergency measures. If the impedance change rate is not greater than the set threshold, repeat steps 3 to 5.

2. The thermal runaway early warning method for an energy storage system according to claim 1, characterized in that: The step 1 includes: installing a detection chip on each battery cell of the energy storage system, and a plurality of detection chips are communicatively connected to a host computer via a battery cell connection system.

3. The thermal runaway early warning method for an energy storage system according to claim 1, characterized in that: The electrochemical impedance spectroscopy data includes the real part of impedance, the imaginary part of impedance, the impedance amplitude, and the impedance phase.

4. The thermal runaway early warning method for an energy storage system according to claim 1, characterized in that: The data filtering algorithm includes: establishing a data buffer and storing several groups of data, averaging the data in the buffer, and recording the average value as Zavg; each time new impedance data is collected, it is compared with the average value of the buffer; if the new impedance data is greater than Zavg+5, the new impedance data is recorded as Zavg+5 and placed in the buffer; if the new impedance data is less than Zavg-5, the new impedance data is recorded as Zavg-5 and placed in the buffer.

5. The thermal runaway early warning method for an energy storage system according to claim 1, characterized in that: The step five includes: calculating the real-time impedance change rate based on the electrochemical impedance spectroscopy data, and repeating steps three to five if the real-time impedance change rate is not greater than a set threshold.

6. The thermal runaway early warning method for an energy storage system according to claim 1, characterized in that: The step five includes: The real-time impedance real part change rate is calculated based on the electrochemical impedance spectroscopy data. If the real-time impedance real part change rate exceeds the set threshold for the first time, an alarm signal is issued and the real-time impedance real part is recorded as the first impedance real part. The real-time impedance real part is not greater than the first impedance real part within the subsequent set time. After eliminating the first impedance real part, repeat steps 3 to 5.

7. The thermal runaway early warning method for an energy storage system according to claim 1, characterized in that: The step five includes: calculating the real-time impedance real part change rate based on the electrochemical impedance spectroscopy data; if the real-time impedance real part change rate is greater than a set threshold for the first time, issuing an alarm signal and recording the real-time impedance real part as the first impedance real part; if the real-time impedance real part is greater than the first impedance real part within a subsequent set time, issuing an alarm signal and cutting off the energy storage system circuit to prevent thermal runaway.

8. The thermal runaway early warning method for an energy storage system according to any one of claims 6, 7, and 8, characterized in that: The calculation formula of the real-time impedance real part change rate is as follows: ， Where k represents the rate of change of the real part of the impedance, Zr1 represents the real part of the impedance T minutes ago, Zr2 represents the real part of the impedance at present, and T represents the detection period.

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