Method and system for monitoring internal temperature of single battery cell of energy storage battery

Abstract

The invention belongs to a temperature monitoring method, and provides a method and a system for monitoring the internal temperature of a single cell of an energy storage battery to solve the technical problems that an existing method for measuring the temperature of the energy storage battery cannot warn a safety accident in time or required equipment is huge and high in cost. And measuring the excitation voltage amplitude or impedance of the single cell, and querying the internal temperature calibration table of the single cell according to the excitation voltage amplitude or impedance of the single cell, so as to obtain the estimated value of the internal temperature value of the current single cell. According to the monitoring method, in the actual application process of the energy storage system, the internal temperature value of each single cell in the battery pack can be accurately monitored on line. And a temperature early warning range can be set, and when the internal temperature value of the single battery core exceeds the temperature early warning range, early warning is actively reported, so that accidents are prevented, and the occurrence of safety accidents is reduced.

Description

Technical Field

[0001] The present application relates to a temperature monitoring method, and specifically to a method and system for monitoring the internal temperature of a single cell of an energy storage battery. Background Art

[0002] With the transformation of the global energy structure and the rapid development of renewable energy such as wind power and photovoltaics, the energy storage industry is becoming increasingly large. As a key technology, energy storage batteries are crucial to solving the volatility and intermittency problems of renewable energy.

[0003] Energy storage batteries have safety risks such as thermal runaway, overcharging, and over-discharging during the charging and discharging process. Among them, thermal runaway is the main factor causing energy storage battery fires, which will cause uncontrollable temperature rise inside the energy storage battery, which may cause fire or explosion. Therefore, it is necessary to effectively measure the actual temperature of the energy storage battery and conduct active early warning to ensure the safe and stable operation of the energy storage battery and reduce the occurrence of energy storage battery safety accidents.

[0004] At present, the temperature inside the battery is generally estimated by installing a temperature sensor on the surface of the energy storage battery or using an electrochemical workstation. However, the method of installing a temperature sensor on the surface of the energy storage battery cannot obtain the temperature changes inside the energy storage battery in a timely manner, and cannot warn of safety accidents in a timely manner. The method of using an electrochemical workstation to estimate the internal temperature of the energy storage battery requires large equipment and high cost. Both methods are difficult to achieve commercial application from the perspectives of assembly, cost, and safety. Summary of the invention

[0005] In view of the technical problems that current methods for measuring the temperature of energy storage batteries cannot promptly warn of safety accidents or require bulky and costly equipment, this application provides a method and system for monitoring the internal temperature of a single cell of an energy storage battery.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions: In a first aspect, the present application proposes a method for monitoring the internal temperature of a single cell of an energy storage battery, comprising: Injecting excitation current into the single cell battery, and measuring the excitation voltage amplitude or impedance of the single cell battery; According to the excitation voltage amplitude or impedance of the single cell, query the single cell internal temperature calibration table to obtain an estimated value of the current single cell internal temperature value; The method for constructing the internal temperature calibration table of the single cell comprises: The battery pack is allowed to reach different preset SOC values ​​respectively, and is left to stand for a first preset time at different preset SOC values, and then steps (1) to (4) are performed: (1) The battery pack is heated or cooled in a preset step in sequence, and after each heating or cooling, the battery pack is left to stand for a second preset time, and then steps (1-1) and (1-2) are performed, wherein the temperature of the battery pack after the temperature is increased or decreased in the preset step is recorded as the battery pack temperature: (1-1) injecting excitation currents of different preset frequencies into each single battery in the battery pack, and detecting the excitation voltage and excitation current of each single battery as detection parameters; (1-2) calculating the excitation voltage amplitude or impedance of each single battery at different preset frequencies according to the detection parameters; (2) For different preset frequencies, compare the changes in the excitation voltage amplitude or impedance at different battery pack temperatures, and select the preset frequency corresponding to the maximum change in the excitation voltage amplitude or impedance as the pre-selected frequency value; (3) Calculate the internal temperature of the single cell according to the excitation voltage amplitude or impedance at the preselected frequency; (4) The preselected frequency value, different battery pack temperatures, corresponding excitation voltage amplitude or corresponding impedance, and corresponding single cell internal temperature value are used as the content corresponding to the current preset SOC value in the single cell internal temperature calibration table.

[0007] Further, calculating the excitation voltage amplitude or impedance of each current single battery at different preset frequencies according to the detection parameters includes: using a DFT algorithm to calculate the excitation voltage amplitude or impedance of each current single battery at different preset frequencies.

[0008] Furthermore, it also includes setting a temperature warning range, and issuing a warning when the estimated value of the internal temperature of the current single cell exceeds the temperature warning range.

[0009] Furthermore, the measurement to obtain the excitation voltage amplitude or impedance of the single battery cell also includes: measuring the surface temperature of the battery cell of each single battery cell; After obtaining the estimated value of the current internal temperature value of the single battery cell, it also includes: calculating the change rate of the current internal temperature value of the single battery cell and the surface temperature of the battery cell of each single battery cell in real time according to the surface temperature of the battery cell of each single battery cell and the estimated value of the current internal temperature value of the single battery cell, and if any change rate exceeds the temperature change rate threshold, an early warning is issued.

[0010] Furthermore, the steps of respectively making the battery pack reach different preset SOC values ​​include: In an environment of 20°C, the battery pack is charged or discharged at a constant power of 0.5P to make the battery pack reach different preset SOC values.

[0011] Furthermore, the first preset time is 30 minutes, and the second preset time is 4 hours.

[0012] Furthermore, the different preset frequencies include 100-300 Hz.

[0013] Furthermore, the step of sequentially raising or lowering the temperature of the battery pack according to a preset step includes: The temperature can be raised or lowered in 10℃ steps within the temperature range of -40℃-60℃.

[0014] Furthermore, the steps of respectively making the battery pack reach different preset SOC values ​​include: The SOC value is changed in 10% steps within the SOC value range of 0%-100%.

[0015] In a second aspect, the present application proposes a system for monitoring the internal temperature of a single cell of an energy storage battery, comprising: An excitation current injection module is used to inject an excitation current into a single cell and measure the excitation voltage amplitude or impedance of the single cell; The table lookup module is used to query the internal temperature calibration table of the single cell according to the excitation voltage amplitude or impedance of the single cell, and obtain an estimated value of the current internal temperature value of the single cell; The method for constructing the internal temperature calibration table of the single cell comprises: The battery pack is allowed to reach different preset SOC values ​​respectively, and is left to stand for a first preset time at different preset SOC values, and then steps (1) to (4) are performed: (1) The battery pack is heated or cooled in a preset step in sequence, and after each heating or cooling, the battery pack is left to stand for a second preset time, and then steps (1-1) and (1-2) are performed, wherein the temperature of the battery pack after the temperature is increased or decreased in the preset step is recorded as the battery pack temperature: (1-1) injecting excitation currents of different preset frequencies into each single battery in the battery pack, and detecting the excitation voltage and excitation current of each single battery as detection parameters; (1-2) calculating the excitation voltage amplitude or impedance of each single battery at different preset frequencies according to the detection parameters; (2) For different preset frequencies, compare the changes in the excitation voltage amplitude or impedance at different battery pack temperatures, and select the preset frequency corresponding to the maximum change in the excitation voltage amplitude or impedance as the pre-selected frequency value; (3) Calculate the internal temperature of the single cell according to the excitation voltage amplitude or impedance at the preselected frequency; (4) The preselected frequency value, different battery pack temperatures, corresponding excitation voltage amplitude or corresponding impedance, and corresponding single cell internal temperature value are used as the content corresponding to the current preset SOC value in the single cell internal temperature calibration table.

[0016] Compared with the prior art, this application has the following beneficial effects: The present application proposes a method for monitoring the internal temperature of a single cell of an energy storage battery. During the monitoring process, it is only necessary to inject an excitation current into the single cell, measure the excitation voltage amplitude or impedance of the single cell, and query the internal temperature calibration table of the single cell according to the excitation voltage amplitude or impedance of the single cell to obtain an estimate of the current internal temperature value of the single cell. In the actual application of the energy storage system, the monitoring method of the present application can accurately monitor the internal temperature value of each single cell in the battery pack online. In practical applications, a temperature warning range can also be set. When the internal temperature value of the single cell exceeds the temperature warning range, an early warning is actively reported to prevent accidents and reduce the occurrence of safety accidents. In addition, during the monitoring process, only a table lookup is needed to quickly and accurately obtain the estimated value of the current internal temperature value of the single cell, without the need for other large equipment, which reduces the monitoring cost and is also conducive to the promotion and application of the present application.

[0017] The present application also proposes a system for monitoring the internal temperature of a single cell of an energy storage battery, which has all the advantages of the above-mentioned method for monitoring the internal temperature of a single cell of an energy storage battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic diagram of a method for monitoring the internal temperature of a single cell of an energy storage battery according to the present application; Figure 2 A schematic diagram of the internal temperature monitoring system of the energy storage battery cell of the present application; Figure 3 A schematic diagram of an implementation method of the internal temperature monitoring method of a single cell of an energy storage battery of the present application. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0023] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] As a key component of modern energy storage, energy storage batteries face multiple safety risks during the charging and discharging process, among which thermal runaway is particularly prominent, which may cause a sharp rise in the temperature inside the battery, leading to fire or even explosion, posing a huge threat to personnel safety and property. Therefore, it is crucial to accurately and real-timely measure the true temperature of energy storage batteries and implement an effective early warning mechanism to ensure the safe and stable operation of energy storage systems.

[0027] At present, the commonly used energy storage battery temperature measurement methods mainly include the surface temperature sensor method and the electrochemical workstation estimation method. Among them, the surface temperature sensor method usually monitors the temperature of the energy storage battery shell by installing a temperature sensor on the outer surface of the energy storage battery. However, since it takes a certain amount of time for the internal heat of the energy storage battery to be transferred to the surface, the surface temperature cannot immediately reflect the actual temperature condition inside the energy storage battery. This delay may result in the failure to timely warn of safety risks such as thermal runaway. In addition, the surface temperature is greatly affected by environmental factors, such as ambient temperature and wind speed, which will further reduce the accuracy of the measurement. The electrochemical workstation estimation method measures the electrochemical characteristics of the energy storage battery by applying specific electrochemical test conditions, such as potential scanning, constant current charge and discharge, and estimates the internal temperature of the energy storage battery based on this. However, the electrochemical workstation equipment is large and costly, and is not suitable for large-scale commercial applications. Secondly, the estimated temperature depends on complex electrochemical models and algorithms, which may have large errors in different types of energy storage batteries and working conditions. Finally, the electrochemical test itself may cause certain damage to the energy storage battery or affect its normal use.

[0028] Based on the above situation, the present application proposes a method and system for monitoring the internal temperature of a single cell of an energy storage battery. The present application is described in detail below in conjunction with embodiments and drawings.

[0029] like Figure 1 FIG. 1 is a schematic diagram of a method for monitoring the internal temperature of a single cell of an energy storage battery according to the present invention, which may include: S101, injecting an excitation current into a single cell and measuring the excitation voltage amplitude or impedance of the single cell.

[0030] By applying an excitation current of known frequency and amplitude to a single cell, the voltage response generated by the single cell can be measured, and the excitation voltage amplitude of the single cell can be obtained or the impedance can be calculated. This voltage response is related to the internal state of the single cell (including temperature). In practical applications, specialized test equipment or a battery management system (BMS) can be used to inject the excitation current and measure the voltage response. The frequency and amplitude of the excitation current can be selected according to the characteristics of the single cell to ensure that temperature-related voltage changes can be stimulated.

[0031] S102, querying a single cell internal temperature calibration table according to the excitation voltage amplitude or impedance of the single cell, and obtaining an estimated value of the current single cell internal temperature value.

[0032] When obtaining the estimated value of the current internal temperature value of the single cell, the present application uses a pre-established single cell internal temperature calibration table to convert the measured voltage amplitude or impedance into the estimated value of the internal temperature value of the single cell.

[0033] The method for constructing the internal temperature calibration table of the single cell comprises: The battery pack is allowed to reach different preset SOC (State of Charge) values ​​respectively, and is left to stand for a first preset time at different preset SOC values, and then steps (1) to (4) are performed: It should be noted that the first preset time of standing at different preset SOC values ​​is to ensure that at each SOC value, the internal state (such as temperature distribution) of the single cell is balanced and any transient effects caused by the charging or discharging process are eliminated.

[0034] (1) The battery pack is heated or cooled in steps according to a preset step, and after each heating or cooling, the battery pack is left to stand for a second preset time, and then steps (1-1) and (1-2) are performed, wherein the temperature of the battery pack after the temperature is increased or decreased in steps according to the preset step is recorded as the battery pack temperature.

[0035] It should be noted that the second preset time of standing still after each heating or cooling is to ensure that the internal temperature of the single battery cell is uniform.

[0036] (1-1) Injecting excitation currents of different preset frequencies into each single cell in the battery pack, and detecting the excitation voltage and excitation current of each single cell as detection parameters.

[0037] (1-2) Calculate the excitation voltage amplitude or impedance of each single battery at different preset frequencies according to the detection parameters.

[0038] (2) For different preset frequencies, compare the changes in the excitation voltage amplitude or impedance at different battery pack temperatures, and select the preset frequency corresponding to the maximum change in the excitation voltage amplitude or impedance as the pre-selected frequency value.

[0039] The present application finds the preset frequency that is most sensitive to temperature changes, that is, the preselected frequency value at which the change in excitation voltage amplitude or impedance is the largest.

[0040] (3) Calculate the internal temperature of the single cell based on the excitation voltage amplitude or impedance at the preselected frequency.

[0041] The response data at the preselected frequency value can be used to calculate the internal temperature value of the single cell through a mathematical relationship or model. It is used to match or fit the response data with a known temperature-response relationship.

[0042] (4) The preselected frequency value, different battery pack temperatures, corresponding excitation voltage amplitude or corresponding impedance, and corresponding single cell internal temperature value are used as the content corresponding to the current preset SOC value in the single cell internal temperature calibration table.

[0043] The pre-selected frequency, battery pack temperature, excitation voltage amplitude (or impedance) and single cell internal temperature values ​​are organized into a table for subsequent temperature estimation. For each SOC value, repeat the above steps and organize the obtained data into a table or database form for quick query and use.

[0044] The present application can be applied to energy storage battery management systems, accurately and directly reflecting the internal temperature of single cells, and combining the temperature warning range to actively warn and avoid the occurrence of safety accidents. The implementation cost is low and it can be commercially applied to energy storage battery management systems.

[0045] The following is an example of the method for monitoring the internal temperature of a single cell of an energy storage battery of the present application, which further explains the present application: Step 1: At 20°C, charge or discharge the battery pack at a constant power of 0.5P until the battery pack reaches the preset SOC value. After charging or discharging, let it stand for 30 minutes.

[0046] Constant power charging or discharging can ensure that the power of the battery pack remains stable during the charging or discharging process.

[0047] Step 2: Heat up or cool down the battery pack after charging or discharging to make the battery pack reach the preset battery pack temperature and let it stand for 4 hours.

[0048] Step 3: Inject an excitation current with a frequency of 100 Hz to 300 Hz into each single cell in the battery pack, and detect the excitation voltage and excitation current of each single cell.

[0049] Step 4: Use the DFT (Discrete Fourier Transform) algorithm to calculate the excitation voltage amplitude or impedance of each single cell under the current conditions.

[0050] In practical applications, the excitation voltage and excitation current can be converted into digital signals. The DFT algorithm is applied to the excitation voltage and excitation current of each single battery to obtain a complex number representation in the frequency domain. The excitation voltage amplitude or impedance at each frequency point is calculated by taking the absolute value of the complex number or the ratio of the real part to the imaginary part.

[0051] Step 5: Change the battery pack temperature in the range of -40°C to 60°C in steps of 10°C, and repeat steps 2 to 4 to obtain and record the excitation voltage amplitude or impedance of the single cell inside the battery pack under the same SOC and different battery pack temperature conditions.

[0052] Step 6: Use the screening and comparison model to compare the excitation voltage amplitude or impedance at different frequencies and the values ​​measured at different temperatures, and select the frequency value f with the largest change in the excitation voltage amplitude or impedance as the pre-selected frequency value, and calculate the internal temperature value of the single cell according to the excitation voltage amplitude or impedance at the pre-selected frequency.

[0053] Step 7: Change the SOC value in the range of 0%-100% by 10% in steps, and repeat steps 1 to 6 to obtain and record the pre-selected frequency values ​​at different SOCs and different battery pack temperatures. The pre-selected frequency values, different battery pack temperatures, corresponding excitation voltage amplitudes or corresponding impedances, and corresponding single cell internal temperature values ​​are used to form a single cell internal temperature calibration table.

[0054] In practical applications, during the application of the energy storage system, the energy storage system knows the SOC value of each single cell inside the battery pack. By injecting excitation current into the single cell, the excitation voltage amplitude or impedance of the single cell can be measured. By querying the internal temperature calibration table of the single cell, the estimated value of the current internal temperature value of the single cell can be obtained, which is recorded as TI.

[0055] In order to play the role of early warning, the temperature warning range can be set to Tmin-Tmax. Among them, Tmin is the minimum value of the temperature warning range, and Tmax is the maximum value of the temperature warning range. If the estimated value of the internal temperature of the current single cell exceeds the temperature warning range, it will be judged as the temperature is out of range, and a corresponding warning can be issued.

[0056] In this embodiment, the cell surface temperature TS of each single cell can also be collected. After the estimated value of the current internal temperature of the single cell is obtained, the difference TI-TS between the estimated value of the internal temperature of the single cell and the cell surface temperature of the single cell is compared in real time, and the rate of change of the estimated value of the current internal temperature of the single cell and the cell surface temperature of the single cell is calculated. If any change rate exceeds the temperature change rate threshold, it is also determined that the internal temperature of the current single cell is abnormal, and an early warning is issued.

[0057] Compared with the existing single cell surface temperature measurement technology, this application can accurately obtain the internal temperature of the single cell and warn of battery thermal runaway earlier. The solution of this application can be applied to the battery pack management of energy storage systems in batches at low cost. It can also model and analyze the estimated value of the internal temperature value of the single cell and the rate of change of the surface temperature of the single cell, actively screen abnormal single cells, and provide safety warnings in advance.

[0058] It should be noted that the first preset time and the second preset time in the above embodiment are the preferred values ​​that have been tested and verified to ensure the stability of detection. In addition, in other embodiments of the present application, the battery pack temperature and the preset frequency, as well as the corresponding stepping, can be adjusted according to the accuracy requirements of the single cell internal temperature calibration table.

[0059] like Figure 2 FIG. 1 is a schematic diagram of a temperature monitoring system for a single cell of an energy storage battery according to the present invention, which may include: An excitation current injection module is used to inject an excitation current into a single cell and measure the excitation voltage amplitude or impedance of the single cell; The table lookup module is used to query the internal temperature calibration table of the single cell according to the excitation voltage amplitude or impedance of the single cell, and obtain an estimated value of the current internal temperature value of the single cell; The method for constructing the internal temperature calibration table of the single cell comprises: The battery pack is allowed to reach different preset SOC values ​​respectively, and is left to stand for a first preset time at different preset SOC values, and then steps (1) to (4) are performed: (1) The battery pack is heated or cooled in a preset step in sequence, and after each heating or cooling, the battery pack is left to stand for a second preset time, and then steps (1-1) and (1-2) are performed, wherein the temperature of the battery pack after the temperature is increased or decreased in the preset step is recorded as the battery pack temperature: (1-1) injecting excitation currents of different preset frequencies into each single battery in the battery pack, and detecting the excitation voltage and excitation current of each single battery as detection parameters; (1-2) calculating the excitation voltage amplitude or impedance of each single battery at different preset frequencies according to the detection parameters; (2) For different preset frequencies, compare the changes in the excitation voltage amplitude or impedance at different battery pack temperatures, and select the preset frequency corresponding to the maximum change in the excitation voltage amplitude or impedance as the pre-selected frequency value; (3) Calculate the internal temperature of the single cell according to the excitation voltage amplitude or impedance at the preselected frequency; (4) The preselected frequency value, different battery pack temperatures, corresponding excitation voltage amplitude or corresponding impedance, and corresponding single cell internal temperature value are used as the content corresponding to the current preset SOC value in the single cell internal temperature calibration table.

[0060] It should be noted that in the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the system embodiments described above are merely schematic. For example, the division of each module is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules can be combined or integrated into another device, or some features can be ignored or not executed. The module described as a separate component may or may not be physically separated. The component displayed as a module may be a physical unit or multiple physical units, that is, it may be located in one place, or it may be distributed in multiple different places. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment.

[0061] In addition, each module in each embodiment of the present invention may be integrated into a processing unit, each module may exist physically separately, or two or more modules may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0062] like Figure 3 As shown, it is a schematic diagram of an implementation method of the internal temperature monitoring method of the energy storage battery single cell of the present application, including a control processing chip, an isolation transformer, a control sampling chip, an excitation drive, an excitation voltage / current acquisition, a surface temperature acquisition and a load. During monitoring, the control processing chip sends a signal acquisition command to the control sampling chip through the isolation transformer. After the control sampling chip receives the acquisition command from the control processing chip, it first controls the excitation drive to generate a square wave signal to form a current loop between the energy storage battery and the load. At the same time, the "excitation voltage / current acquisition" measures the current on the load and the excitation voltage generated at both ends of the energy storage battery, and calculates the excitation voltage amplitude or impedance. Similarly, the surface temperature of the energy storage battery is collected through "surface temperature acquisition" for early warning protection comparison. The collected data is fed back to the control sampling chip, and then the control sampling chip returns the data to the control processing chip, and the control processing chip performs the corresponding internal temperature calculation and temperature early warning protection. In addition, after receiving the data information sent by the control sampling chip, the control processing chip calculates the internal temperature value of each single cell by querying the internal temperature calibration table of the single cell.

[0063] In this implementation, each battery cell has an independent control and detection circuit, which can accurately measure the parameters of each battery cell.

[0064] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for monitoring the internal temperature of a single cell of an energy storage battery, characterized in that: include: Injecting excitation current into the single cell battery, and measuring the excitation voltage amplitude or impedance of the single cell battery; According to the excitation voltage amplitude or impedance of the single cell, query the single cell internal temperature calibration table to obtain an estimated value of the current single cell internal temperature value; The method for constructing the internal temperature calibration table of the single cell comprises: The battery pack is allowed to reach different preset SOC values ​​respectively, and is left to stand for a first preset time at different preset SOC values, and then steps (1) to (4) are performed: (1) The battery pack is heated or cooled in a preset step in sequence, and after each heating or cooling, the battery pack is left to stand for a second preset time, and then steps (1-1) and (1-2) are performed, wherein the temperature of the battery pack after the temperature is increased or decreased in the preset step is recorded as the battery pack temperature: (1-1) injecting excitation currents of different preset frequencies into each single battery in the battery pack, and detecting the excitation voltage and excitation current of each single battery as detection parameters; (1-2) calculating the excitation voltage amplitude or impedance of each single battery at different preset frequencies according to the detection parameters; (2) For different preset frequencies, compare the changes in the excitation voltage amplitude or impedance at different battery pack temperatures, and select the preset frequency corresponding to the maximum change in the excitation voltage amplitude or impedance as the pre-selected frequency value; (3) Calculate the internal temperature of the single cell according to the excitation voltage amplitude or impedance at the preselected frequency; (4) The preselected frequency value, different battery pack temperatures, corresponding excitation voltage amplitude or corresponding impedance, and corresponding single cell internal temperature value are used as the content corresponding to the current preset SOC value in the single cell internal temperature calibration table.

2. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The step of calculating the excitation voltage amplitude or impedance of each current single battery at different preset frequencies according to the detection parameters includes: using a DFT algorithm to calculate the excitation voltage amplitude or impedance of each current single battery at different preset frequencies.

3. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: It also includes setting a temperature warning range, and issuing a warning when the estimated value of the internal temperature of the current single battery cell exceeds the temperature warning range.

4. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The measuring step of obtaining the excitation voltage amplitude or impedance of the single cell also includes: measuring the cell surface temperature of each single cell; After obtaining the estimated value of the current internal temperature value of the single battery cell, it also includes: calculating the change rate of the current internal temperature value of the single battery cell and the surface temperature of the battery cell of each single battery cell in real time according to the surface temperature of the battery cell of each single battery cell and the estimated value of the current internal temperature value of the single battery cell, and if any change rate exceeds the temperature change rate threshold, an early warning is issued.

5. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The method of respectively making the battery pack reach different preset SOC values ​​includes: In an environment of 20°C, the battery pack is charged or discharged at a constant power of 0.5P to make the battery pack reach different preset SOC values.

6. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The first preset time is 30 minutes, and the second preset time is 4 hours.

7. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The different preset frequencies include 100-300 Hz.

8. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The step of sequentially raising or lowering the temperature of the battery pack according to a preset step includes: The temperature can be raised or lowered in 10℃ steps within the temperature range of -40℃-60℃.

9. The method for monitoring the internal temperature of a single cell of an energy storage battery according to claim 1, characterized in that: The method of respectively making the battery pack reach different preset SOC values ​​includes: The SOC value is changed in 10% steps within the SOC value range of 0%-100%.

10. A system for monitoring the internal temperature of a single cell of an energy storage battery, characterized in that: include: An excitation current injection module is used to inject an excitation current into a single cell and measure the excitation voltage amplitude or impedance of the single cell; The table lookup module is used to query the internal temperature calibration table of the single cell according to the excitation voltage amplitude or impedance of the single cell, and obtain an estimated value of the current internal temperature value of the single cell; The method for constructing the internal temperature calibration table of the single cell comprises: The battery pack is allowed to reach different preset SOC values ​​respectively, and is left to stand for a first preset time at different preset SOC values, and then steps (1) to (4) are performed: (1) The battery pack is heated or cooled in a preset step in sequence, and after each heating or cooling, the battery pack is left to stand for a second preset time, and then steps (1-1) and (1-2) are performed, wherein the temperature of the battery pack after the temperature is increased or decreased in the preset step is recorded as the battery pack temperature: (1-1) injecting excitation currents of different preset frequencies into each single battery in the battery pack, and detecting the excitation voltage and excitation current of each single battery as detection parameters; (1-2) calculating the excitation voltage amplitude or impedance of each single battery at different preset frequencies according to the detection parameters; (2) For different preset frequencies, compare the changes in the excitation voltage amplitude or impedance at different battery pack temperatures, and select the preset frequency corresponding to the maximum change in the excitation voltage amplitude or impedance as the pre-selected frequency value; (3) Calculate the internal temperature of the single cell according to the excitation voltage amplitude or impedance at the preselected frequency; (4) The preselected frequency value, different battery pack temperatures, corresponding excitation voltage amplitude or corresponding impedance, and corresponding single cell internal temperature value are used as the content corresponding to the current preset SOC value in the single cell internal temperature calibration table.

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