Method for determining internal temperature of battery pack on line and battery management system comprising same

Abstract

The invention provides a method for determining the internal temperature of a battery pack on line. The method comprises the steps that a heat production model of each battery cell in the battery pack at the current moment is determined; based on the determined heat production model of each battery cell, determining the temperature variation caused by heat production in the battery cell at the current moment; establishing a corresponding heat transfer model based on the simplified point set of each battery cell; based on the heat transfer model corresponding to each battery cell, determining the temperature variation of the equivalent points in the battery cell at the current moment due to heat transfer of other points in the point set; and determining the internal temperature of each battery cell at the current moment based on the internal temperature of the battery cell at the previous moment, the temperature variation caused by heat production in the battery cell at the current moment and the temperature variation caused by heat transfer of other points in the point set at the equivalent points in the battery cell at the current moment. According to the method for online determining the internal temperature of the battery pack, the accuracy of online calculation of the internal temperature of the battery cell can be improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and particularly to a method for online determining the internal temperature of a battery pack and a battery management system including the same. Background Art

[0002] In recent years, with the continuous increase in the ownership of electric vehicles, in the field of electric vehicles, the accurate online calculation of the internal temperature of the battery pack is crucial for improving the overall performance of the Battery Management System (BMS for short). It is directly related to the driving range, safety and user experience of electric vehicles.

[0003] Currently, the online calculation method of the internal temperature of the battery cell often uses the externally sampled temperature as the surface temperature and calculates the heat transfer between the inside and the outer surface based on this temperature. In fact, the outer surface distribution is not uniform, and the externally sampled temperature is often on the tab, and the tab temperature is not equal to the outer surface temperature.

[0004] Based on this, it has become an urgent task for those skilled in the art to propose a method that can more accurately determine the internal temperature of the battery pack online. Summary of the Invention

[0005] In a first aspect, an embodiment of the present application provides a method for online determining the internal temperature of a battery pack. The battery pack includes one or more battery cells, and each battery cell includes an inside of the battery cell, a positive tab and a negative tab. The method includes:

[0006] Determine the heat generation model of each battery cell in the battery pack at the current moment;

[0007] Based on the heat generation model determined for each battery cell, determine the temperature change amount in the inside of the battery cell caused by heat generation at the current moment;

[0008] Based on the simplified point set of each battery cell, establish a corresponding heat transfer model, where the point set at least includes an equivalent point inside the battery cell, an equivalent point of the positive tab, an equivalent point of the negative tab, and an equivalent point at the contact between an external heat source or cold source and the battery cell;

[0009] Based on the heat transfer model corresponding to each battery cell, determine the temperature change amount of the equivalent point inside the battery cell caused by heat transfer from other points in the point set at the current moment;

[0010] Based on the temperature inside the battery cell at the previous moment, the temperature change amount in the inside of the battery cell caused by heat generation at the current moment, and the temperature change amount of the equivalent point inside the battery cell caused by heat transfer from other points in the point set at the current moment, determine the temperature inside the battery cell of each battery cell at the current moment.

[0011] The method for online determination of the internal temperature of the battery pack in this application determines the heat generation model for each battery cell when calculating heat generation, and then establishes a heat transfer model based on a point set including multiple equivalent points. Compared with the existing heat transfer model that does not determine the heat generation model for each battery cell in the battery pack and only considers a single point on the outer surface, the accuracy of the calculation result is improved.

[0012] In some embodiments, the heat generation model includes a first heat generation model and a second heat generation model, and the first heat generation model is different from the second heat generation model. The steps for determining the heat generation model of each battery cell in the battery pack at the current moment include:

[0013] Determine whether the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is less than the corresponding preset threshold;

[0014] In the case where it is determined that the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is less than the corresponding preset threshold, determine that each battery cell adopts the first heat generation model;

[0015] and / or,

[0016] In the case where it is determined that the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is not less than the corresponding preset threshold, determine whether each battery cell is a lithium iron phosphate battery cell or a lithium manganese iron phosphate battery cell;

[0017] In the case where it is determined that each battery cell is a lithium iron phosphate battery cell or a lithium manganese iron phosphate battery cell, determine whether the state of charge of each battery cell at the current moment is in the plateau region, where the plateau region is configured as a region where the open-circuit voltage of the battery cell is not affected by the state of charge of the battery cell;

[0018] In the case where it is determined that the state of charge of each battery cell is in the plateau region, determine that each battery cell adopts the second heat generation model.

[0019] In some embodiments, the steps for determining whether each battery cell in the battery pack adopts the first heat generation model or the second heat generation model at the current moment further include:

[0020] In the case where it is determined that each battery cell is not a lithium iron phosphate battery cell and a lithium manganese iron phosphate battery cell or in the case where it is determined that the state of charge of each battery cell is not in the plateau region, respectively determine the first maximum error of the first heat generation model and the second maximum error of the second heat generation model for each battery cell;

[0021] In the case where the first maximum error is less than or equal to the second maximum error, determine that each battery cell adopts the first heat generation model;

[0022] In the case where the first maximum error is greater than the second maximum error, determine that each battery cell adopts the second heat generation model.

[0023] In some embodiments, when it is determined that each battery cell is not a lithium iron phosphate battery cell or a lithium iron manganese phosphate battery cell, or when it is determined that the state of charge of the battery cell is not in the plateau region, the steps of respectively determining the first maximum error of the first heat generation model and the second maximum error of the second heat generation model for each battery cell include:

[0024] Determine the state of charge of each battery cell at the current moment;

[0025] Based on the state of charge of each battery cell at the current moment and the temperature inside each battery cell at the previous moment, determine the rate of change of the open-circuit voltage of each battery cell with respect to the state of charge of the battery cell;

[0026] Based on the rate of change of the open-circuit voltage of each battery cell with respect to the state of charge of the battery cell, determine the maximum value of the rate of change of the open-circuit voltage with respect to the state of charge of the battery cell;

[0027] Based on the absolute value of the polarization voltage of each battery cell, determine the minimum value of the absolute value of the polarization voltage;

[0028] Based on the maximum value of the rate of change of the open-circuit voltage with respect to the state of charge of the battery cell, the minimum value of the absolute value of the polarization voltage, the preset estimation accuracy of the state of charge of each battery cell, and the preset voltage sampling error, determine the first maximum error of the first heat generation model;

[0029] And / or,

[0030] Based on the temperature inside each battery cell at the previous moment, determine the minimum value of the temperature inside the battery cell;

[0031] Based on the minimum value of the temperature inside the battery cell and the preset mapping relationship between temperature and error, determine the second maximum error of the second heat generation model.

[0032] In some embodiments, the steps of determining the temperature change amount inside each battery cell caused by heat generation at the current moment based on the heat generation model determined for each battery cell include:

[0033] When it is determined that each battery cell adopts the first heat generation model, based on the current of each battery cell at the current moment, the equivalent resistance value of each battery cell, the temperature inside each battery cell at the previous moment, the rate of change of the open-circuit voltage of each battery cell with respect to temperature, and the preset period, determine the heat generation inside each battery cell at the current moment;

[0034] And / or,

[0035] When it is determined that the second heat generation model is adopted for each battery cell, based on the polarization voltage of each battery cell at the current moment, the temperature inside each battery cell at the previous moment, the rate of change of the open-circuit voltage of each battery cell with temperature, the current of each battery cell at the current moment, and a preset period, determine the heat generation inside each battery cell at the current moment;

[0036] Based on the heat generation inside each battery cell at the current moment and the heat capacity of each battery cell, determine the temperature change amount inside each battery cell caused by heat generation at the current moment.

[0037] In some embodiments, it further includes:

[0038] When the external heat source or cold source is a solid medium, based on the corresponding current, thermal resistance, heat capacity, and preset period at the current moment, determine the temperature change amounts caused by heat generation at the positive electrode tab of each battery cell, the negative electrode tab of each battery cell, and the contact between the external heat source or cold source and each battery cell at the current moment respectively;

[0039] Based on the heat transfer model corresponding to each battery cell, determine the temperature change amounts caused by heat transfer from the equivalent point inside each battery cell to the equivalent point of the positive electrode tab of each battery cell, the equivalent point of the negative electrode tab of each battery cell, and the equivalent point of the contact between the external heat source or cold source and each battery cell at the current moment respectively;

[0040] Based on the temperature at the previous moment, the temperature change amount caused by heat generation at the current moment, and the temperature change amount caused by heat transfer at the current moment, determine the temperatures of the positive electrode tab of each battery cell, the negative electrode tab of each battery cell, and the contact between the external heat source or cold source and each battery cell at the current moment respectively;

[0041] Take the temperatures of the positive electrode tab of each battery cell, the negative electrode tab of each battery cell, and the contact between the external heat source or cold source and each battery cell at the current moment as the temperatures of the corresponding equivalent points at the current moment respectively;

[0042] And / or,

[0043] When the external heat source or cold source is a fluid medium and the flow rate is greater than a preset threshold, based on the outlet temperature at the current moment, the inlet temperature at the current moment, and the position of each battery cell relative to the external heat source or cold source, determine the temperature at the contact between the external heat source or cold source and each battery cell at the current moment.

[0044] In some embodiments, the battery pack includes a plurality of battery cells. The point set includes equivalent points inside the battery cells, equivalent points of the positive electrode tabs, equivalent points of the negative electrode tabs, equivalent points at the contact points between the external heat source or cold source and the battery cells, and equivalent points at the contact points between adjacent battery cells. The step of determining the temperature change amount of the equivalent points inside each battery cell at the current moment due to heat transfer from other equivalent points in the point set based on the heat transfer model corresponding to each battery cell includes:

[0045] Based on the heat transfer model corresponding to each battery cell, determine the heat transfer factors characterizing the heat transfer of other equivalent points to the equivalent points inside the battery cell at the current moment;

[0046] Based on the temperatures of the equivalent points in the point set at the previous moment and the heat transfer factors characterizing the heat transfer of other equivalent points to the equivalent points inside each battery cell at the current moment, determine the temperature change amount of the equivalent points inside the battery cell at the current moment due to heat transfer from other equivalent points in the point set.

[0047] In some embodiments, the step of determining the heat transfer factors characterizing the heat transfer of other equivalent points to the equivalent points inside the battery cell at the current moment based on the heat transfer model corresponding to each battery cell includes:

[0048] Based on the heat transfer model corresponding to each battery cell, determine the heat transfer rate and heat transfer distance from any other equivalent point in the point set to the equivalent point inside the battery cell, and the heat capacity inside the battery cell;

[0049] Based on the heat transfer rate, heat transfer distance, heat capacity inside the battery cell, and a preset period, determine the heat transfer factors characterizing the heat transfer of any other equivalent point to the equivalent point inside each battery cell at the current moment.

[0050] In some embodiments, when the dormancy duration of each battery cell is greater than or equal to the preset dormancy duration, based on the temperature of the temperature sampling point of the battery management system, determine the initial temperature value inside each battery cell; and / or,

[0051] When the dormancy duration of each battery cell is less than the preset dormancy duration, based on the temperature inside each battery cell before the last power-off as the temperature inside the battery cell at the previous moment and the dormancy duration as the preset period, determine the initial temperature value inside each battery cell.

[0052] In some embodiments, it further includes:

[0053] When the temperature sampling point of the battery management system is located at the positive electrode tab and / or negative electrode tab of any battery cell, determine whether the difference between the temperature of the temperature sampling point and the corresponding positive electrode tab and / or negative electrode tab of each determined battery cell is greater than the sum of the sampling temperature error and the preset threshold and lasts for the preset duration;

[0054] When the difference between the temperature of the temperature sampling point and the corresponding positive electrode tab and / or negative electrode tab of each determined battery cell is greater than the sum of the sampling temperature error and the preset threshold for a preset duration, the parameters are corrected, and the parameters include correcting each heat transfer factor from any other equivalent point in the point set to the equivalent point inside each battery cell and / or the initial temperature value inside each battery cell;

[0055] Based on the corrected parameters, the temperatures inside each battery cell, at the positive electrode tab, at the negative electrode tab, and at the contact between the external heat source or cold source and the battery cell within the past time period are re-determined.

[0056] In a second aspect, an embodiment of the present application provides a battery management system, including: a processor and a memory, where a computer program is stored on the memory, and the processor is configured to execute the computer program to implement the method for online determining the internal temperature of the battery pack in any one of the first aspects. Description of the Drawings

[0057] Figure 1 A schematic diagram of an application scenario showing a method for online determining the internal temperature of a battery pack provided by some embodiments of the present application;

[0058] Figure 2 A flowchart showing a method for online determining the internal temperature of a battery pack provided by some embodiments of the present application;

[0059] Figure 3a Show Figure 1 A perspective view of the battery cell C in

[0060] Figure 3b Show Figure 1 A side view of the battery cell C in

[0061] Figure 3c Show Figure 1 A top view of the battery cell C in

[0062] Figure 4 A flowchart showing a method for determining the heat generation model of each battery cell in the battery pack at the current moment provided by some embodiments of the present application;

[0063] Figure 5 A flowchart showing a method for determining the first maximum error of the first heat generation model and the second maximum error of the second heat generation model respectively adopted by the battery cell provided by some embodiments of the present application;

[0064] Figure 6 A flowchart showing a method for determining the temperature change amount inside the battery cell caused by heat generation at the current moment provided by some embodiments of the present application;

[0065] Figure 7A flowchart showing the determination of the temperature change amount of an equivalent point inside a battery cell at the current moment due to heat transfer from other equivalent points in a point set according to some embodiments of the present application;

[0066] Figure 8 A flowchart showing the determination of each heat transfer factor characterizing the heat transfer of other equivalent points to an equivalent point inside a battery cell at the current moment according to some embodiments of the present application;

[0067] Figure 9 A flowchart showing the determination of the temperature of each equivalent point in a point set at the current moment according to some embodiments of the present application;

[0068] Figure 10 A flowchart showing the closed-loop correction according to some embodiments of the present application;

[0069] Figure 11 A block diagram showing a SoC (System on Chip) according to some embodiments of the present application. Detailed implementation manners

[0070] The following will describe the detailed implementation manners of the present application in conjunction with the accompanying drawings.

[0071] Figure 1 A schematic diagram of an application scenario of a method for online determining the internal temperature of a battery pack according to some embodiments of the present application. The battery pack may include, for example, Figure 1 as shown, three battery cells, namely battery cell A, battery cell C, and battery cell B. It may also include less than or more than three battery cells, or may only include one battery cell, which is not specifically limited herein. A battery cell includes the inside of the battery cell (or the battery cell body), a positive electrode tab, and a negative electrode tab. When the battery pack is applied in, for example, the field of electric vehicles, each battery cell in the battery pack is in contact with an external heat source or cold source. As Figure 1 shown, the bottoms of battery cell A, battery cell C, and battery cell B are all in contact with an external heat source or cold source, so that the temperature of each battery cell can be controlled within a better range, thereby improving battery performance, extending the service life, and ensuring safety. The external heat source or cold source may be in the form of a fluid or a solid (such as a heating film), and thus heat can be transferred between the external heat source or cold source and each battery cell to control its temperature range.

[0072] Figure 2 A flowchart showing a method for online determining the internal temperature of a battery pack according to some embodiments of the present application. The method includes the following steps:

[0073] Step S21, determining the heat generation model of each battery cell in the battery pack at the current moment;

[0074] Step S22: Based on the heat generation model determined for each battery cell, determine the temperature change amount inside the battery cell caused by heat generation at the current moment;

[0075] Step S23: Based on the simplified point set of each battery cell, establish a corresponding heat transfer model, where the point set at least includes the equivalent points inside the battery cell, the equivalent points of the positive electrode tab, the equivalent points of the negative electrode tab, and the equivalent points at the contact between the external heat source or cold source and the battery cell;

[0076] Step S24: Based on the heat transfer model corresponding to each battery cell, determine the temperature change amount of the equivalent points inside the battery cell caused by heat transfer from other points within the point set at the current moment;

[0077] Step S25: Based on the temperature inside the battery cell at the previous moment, the temperature change amount inside the battery cell caused by heat generation at the current moment, and the temperature change amount of the equivalent points inside the battery cell caused by heat transfer from other points within the point set at the current moment, determine the temperature inside each battery cell at the current moment.

[0078] It should be noted that in the case where the battery pack includes only one battery cell, the point set includes the equivalent points inside the battery cell, the equivalent points of the positive electrode tab, the equivalent points of the negative electrode tab, and the equivalent points at the contact between the external heat source or cold source and the battery cell; in the case where the battery pack includes multiple battery cells (for example, Figure 1 the three battery cells shown), the point set includes the equivalent points inside the battery cell, the equivalent points of the positive electrode tab, the equivalent points of the negative electrode tab, the equivalent points at the contact between the external heat source or cold source and the battery cell, and the equivalent points at the contact between adjacent battery cells and this battery cell.

[0079] Figure 3a shows Figure 1 the three-dimensional view of battery cell C in Figure 3b shows Figure 1 the side view of battery cell C in Figure 3c shows Figure 1 the top view of battery cell C in Figures 3a - 3c The following further describes the point set taking battery cell C as an example in the case where the battery pack includes three battery cells as shown in Figure 1

[0080] Relative to battery cell C, battery cells A and B are its adjacent battery cells. Figures 3a - 3c The black dot pattern (●) shown in Figure 3a and Figure 3b is the equivalent point inside battery cell B. The black plus pattern (+) shown in Figure 3b is the equivalent point of the positive electrode tab of battery cell B, the black minus pattern (-) is the equivalent point of the negative electrode tab of battery cell B, and the black diamond pattern (◆) is the equivalent point at the contact between the external heat source or cold source and battery cell B. Figure 3cThe equivalent points at the contacts between adjacent battery cells A and adjacent battery cell B and battery cell C are shown by the black triangular figure (▲). It should be noted that although the above shows the point set taking battery cell C as an example when the battery pack includes three battery cells, those skilled in the art can understand the point set taking battery cell A or battery cell B as an example when the battery pack includes three battery cells, and the point sets of each battery cell when the battery pack includes more than three battery cells.

[0081] According to the method for online determining the internal temperature of a battery pack in the present application, since it determines the heat generation model for each battery cell in the battery pack to calculate the temperature change inside each battery cell caused by heat generation, and then establishes a heat transfer model based on the simplified point set of each battery cell to calculate the temperature change inside each battery cell caused by heat transfer, and further online determines the temperature inside each battery cell of the battery pack. In other words, the method for online determining the internal temperature of a battery pack in the present application determines the heat generation model for each battery cell when calculating heat generation, and then establishes a heat transfer model based on the point set including multiple equivalent points. Compared with the existing heat transfer model that does not determine the heat generation model for each battery cell in the battery pack and only considers a point on the outer surface, the accuracy of the calculation result is improved.

[0082] In some embodiments, the heat generation model includes a first heat generation model and a second heat generation model, and the first heat generation model is different from the second heat generation model.

[0083] Figure 4 The flowchart showing the determination of the heat generation model of each battery cell in the battery pack at the current moment according to some embodiments of the present application is shown. The following will be combined with Figure 4 Specifically introduce how to determine the heat generation model of each battery cell in the battery pack at the current moment.

[0084] Step 211, determine whether the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is less than the corresponding preset threshold.

[0085] Among them, the absolute value of the current and the absolute value of the current rate of each battery cell at the current moment can be determined based on the current value of each battery cell collected in real time. Since the current flowing through each battery cell and the battery pack is the same, the current value is also the current value flowing through the battery pack. The absolute value of the polarization voltage of each battery cell at the current moment can be determined based on the terminal voltage of each battery cell at the current moment and its open-circuit voltage (or "steady-state voltage") OCV. The terminal voltage of each battery cell at the current moment can be determined based on the voltage value of the corresponding battery cell collected in real time. Specifically, the polarization voltage is equal to the terminal voltage minus the open-circuit voltage OCV.

[0086] When it is determined that the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is less than the corresponding preset threshold, step 212 is executed to determine that each battery cell adopts the first heat generation model.

[0087] Exemplarily, the preset threshold corresponding to the absolute value of the current can be 2A; the preset threshold corresponding to the absolute value of the current rate can be 0.1C; the preset threshold corresponding to the polarization voltage value can be 0.01V. In other words, when the absolute value of the current of each battery cell at the current moment is less than 2A, or the absolute value of the current rate is less than 0.1C, or the absolute value of the polarization voltage is less than 0.01V, it is determined that each battery cell adopts the first heat generation model. That is, when the battery pack includes three battery cells as shown in Figure 1 When the absolute value of the current of each battery cell among the three battery cells at the current moment is less than 2A, or the absolute value of the current rate of each battery cell at the current moment is less than 0.1C, or the absolute value of the polarization voltage of each battery cell at the current moment is less than 0.01V, it is determined that each battery cell among the three battery cells adopts the first heat generation model.

[0088] When it is determined that the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is not less than the corresponding preset threshold, step 213 is executed to determine whether each battery cell is a lithium iron phosphate battery cell (or "LFP battery cell") or a lithium manganese iron phosphate battery cell (or "LMFP battery cell").

[0089] Exemplarily, when it is determined that the absolute value of the current of each battery cell at the current moment is not less than 2A, the absolute value of the current rate is not less than 0.1C, and the absolute value of the polarization voltage is not less than 0.01V, it is determined whether each battery cell is a lithium iron phosphate battery cell (or "LFP battery cell") or a lithium manganese iron phosphate battery cell (or "LMFP battery cell"). In other words, when the battery pack includes three battery cells as shown in Figure 1 When the absolute value of the current of each battery cell among the three battery cells at the current moment is not all less than 2A, or the absolute value of the current rate of each battery cell at the current moment is not all less than 0.1C, or the absolute value of the polarization voltage of each battery cell at the current moment is not all less than 0.01V, it is determined that each battery cell among the three battery cells adopts the second heat generation model.

[0090] When it is determined that each battery cell is a lithium iron phosphate battery cell or a lithium manganese iron phosphate battery cell, step 214 is executed to determine whether the state of charge SOC of each battery cell at the current moment is in the plateau region. Wherein, the plateau region is configured as a region where the open circuit voltage OCV of the battery cell is not affected by the state of charge SOC of the battery cell or the influence is so small that it can be ignored.

[0091] When it is determined that the state of charge of each battery cell is in the plateau region, step 215 is executed to determine that each battery cell adopts the second heat generation model.

[0092] When it is determined that each battery cell is neither a lithium iron phosphate battery cell nor a lithium iron manganese phosphate battery cell, or when it is determined that the state of charge (SOC) of each battery cell does not fall within the plateau region, step 216 is executed to respectively determine the first maximum error of each battery cell using the first heat generation model and the second maximum error of the second heat generation model. In other words, when the battery pack includes three battery cells as shown in Figure 1 When the three battery cells are neither lithium iron phosphate battery cells nor lithium iron manganese phosphate battery cells, and when the three battery cells are lithium iron phosphate battery cells or lithium iron manganese phosphate battery cells but the state of charge (SOC) of each battery cell does not fall within the plateau region, step 216 is executed.

[0093] Step 217: Determine whether the first maximum error is less than or equal to the second maximum error;

[0094] When the first maximum error is less than or equal to the second maximum error, step 212 is executed to determine that each battery cell uses the first heat generation model.

[0095] When the first maximum error is greater than the second maximum error, step 215 is executed to determine that each battery cell uses the second heat generation model.

[0096] According to the method for online determining the internal temperature of the battery pack in the present application, based on the conditions satisfied by each battery cell in the battery pack at the current moment, it is determined whether to uniformly use the first heat generation model or the second heat generation model, thereby further reducing the calculation error.

[0097] Figure 5 The flowchart shows determining the first maximum error of each battery cell using the first heat generation model and the second maximum error of the second heat generation model according to some embodiments of the present application. The following will be specifically described in combination with Figure 5 how to determine the first maximum error of each battery cell using the first heat generation model and the second maximum error of the second heat generation model.

[0098] Step S2161: Determine the state of charge (SOC) of each battery cell at the current moment.

[0099] Step S2162: Based on the state of charge (SOC) of each battery cell at the current moment and the internal temperature of the battery cell at the previous moment, determine the rate of change of the open circuit voltage with respect to the state of charge of the battery cell, dOCV / dSOC.

[0100] Step S2163: Based on the rate of change of the open circuit voltage with respect to the state of charge (SOC) of each battery cell, dOCV / dSOC, determine the maximum value of the rate of change of the open circuit voltage with respect to the state of charge. In other words, for example, the battery pack includes as shown in Figure 1For the three cells shown, the maximum value of the rate of change dOCV / dSOC of the open-circuit voltage with respect to the state of charge of the cell is the maximum value of the rate of change dOCV / dSOC of the open-circuit voltage with respect to the state of charge of the cells among Cell A, Cell C, and Cell B. Specifically, the rate of change dOCV / dSOC of the open-circuit voltage with respect to the state of charge of the cell can be determined by a preset three-dimensional mapping relationship of SOC-T-OCV.

[0101] Step S2164, based on the absolute value of the polarization voltage of each cell, determine the minimum value of the absolute value of the polarization voltage. In other words, the battery pack includes, for example, Figure 1 the three cells shown, then the minimum value of the absolute value of the polarization voltage is the minimum value of the absolute value of the polarization voltage among Cell A, Cell C, and Cell B.

[0102] Step S2165, based on the maximum value of the rate of change dOCV / dSOC of the open-circuit voltage with respect to the state of charge of the cell, the minimum value of the absolute value of the polarization voltage, the preset estimation accuracy of the state of charge of the corresponding cell, and the preset voltage sampling error, determine the first maximum error of the first heat generation model.

[0103] In some embodiments, the first maximum error of the first heat generation model can be specifically determined by the following formula, that is,

[0104]

[0105] In formula (1), E1 represents the first maximum error of the first heat generation model; K SOC represents the preset estimation accuracy of the state of charge of the cell; MAX ocv / soc represents the maximum value of the rate of change dOCV / dSOC of the open-circuit voltage with respect to the state of charge of the cells in the battery pack; E U preset real-time voltage sampling error; MIN VP represents the minimum value of the absolute value of the polarization voltage of the cells in the battery pack.

[0106] Step S2166, based on the temperature inside each cell at the previous moment, determine the minimum value of the temperature inside the cell.

[0107] In other words, the battery pack includes, for example, Figure 1 the three cells shown, then the minimum value of the temperature inside the cell is the minimum value of the temperature inside the cells among Cell A, Cell C, and Cell B at the previous moment.

[0108] Step S2167, based on the minimum value of the temperature inside the cell and the preset mapping relationship between temperature and error, determine the second maximum error of the second heat generation model.

[0109] In this application, by comparing the errors of the first heat generation model and the second heat generation model, the model with a smaller error is determined as the heat generation model for each battery cell, thereby further reducing the calculation error and improving the accuracy of the calculation result.

[0110] Figure 6 The flowchart shows how to determine the temperature change amount inside the battery cell caused by heat generation at the current moment according to some embodiments of the present application. The following will specifically introduce how to determine the temperature change amount inside the battery cell caused by heat generation at the current moment. Figure 6 Specifically introduce how to determine the temperature change amount inside the battery cell caused by heat generation at the current moment.

[0111] Step 221, when it is determined that each battery cell adopts the first heat generation model, based on the current value of the current of each battery cell at the current moment, the equivalent resistance value of each battery cell, the temperature inside each battery cell at the previous moment, the rate of change of the open-circuit voltage of each battery cell with temperature, and a preset period, determine the heat generation inside each battery cell at the current moment.

[0112] Among them, the current value of the current of the battery cell at the current moment can be the current value of the current flowing through the battery cell collected in real time. The equivalent resistance value of the battery cell can be determined by an existing RC model, and the RC model is a model related to SOC and temperature. In other words, when neither the SOC nor the temperature changes, the equivalent resistance does not change; when at least one of the SOC and the temperature changes, the equivalent resistance may change. The rate of change of the open-circuit voltage of the battery cell with temperature dOCV / dT can also be determined by a preset three-dimensional mapping relationship of SOC-T-OCV. The preset period can be determined based on the real-time voltage sampling period and the processing ability of the chip (for example, 0.1 s).

[0113] In some embodiments, the heat generation calculation based on the first heat generation model can be specifically carried out through the following formula:

[0114]

[0115] In formula (2), Q1 represents the heat generation inside the battery cell at the current moment determined by the battery cell adopting the first heat generation model; I represents the current value of the current of the battery cell at the current moment (that is, the current value collected in real time); R represents the equivalent resistance value of the battery cell; T represents the temperature inside the battery cell at the previous moment; represents the rate of change of the open-circuit voltage of the battery cell with temperature; dt represents the preset period.

[0116] Step 222, when it is determined that each battery cell adopts the second heat generation model, based on the polarization voltage of each battery cell at the current moment, the temperature inside each battery cell at the previous moment, the rate of change of the open-circuit voltage of each battery cell with temperature, the current of each battery cell at the current moment, and a preset period, determine the heat generation inside each battery cell at the current moment.

[0117] Among them, the polarization voltage of the battery cell at the current moment can be determined based on the terminal voltage and its open-circuit voltage (or "steady-state voltage") OCV at the current moment. The terminal voltage can be determined based on the voltage value of the corresponding battery cell collected in real time. Specifically, the polarization voltage is equal to the terminal voltage minus the open-circuit voltage OCV. The rate of change of the open-circuit voltage of the battery cell with temperature dOCV / dT can also be determined through the preset three-dimensional mapping relationship of SOC-T-OCV. The current of the battery cell at the current moment can be the current flowing through the battery cell collected in real time. The preset period can be determined based on the real-time voltage sampling period and the processing ability of the chip (for example, 0.1 s).

[0118] In some embodiments, the heat generation calculation based on the second heat generation model can be specifically carried out through the following formula:

[0119]

[0120] In formula (3), Q2 represents the heat generation inside the battery cell at the current moment determined by the battery cell using the second heat generation model; U represents the terminal voltage of the battery cell at the current moment (i.e., the voltage value collected in real time); OCV represents the open-circuit voltage of the battery cell; T represents the temperature inside the battery cell at the previous moment; represents the rate of change of the open-circuit voltage of the battery cell with temperature; I represents the current value of the battery cell at the current moment (i.e., the current value collected in real time); dt represents the preset period.

[0121] Step 223: Based on the heat generation inside each battery cell at the current moment and the heat capacity of each battery cell, determine the temperature change amount inside each battery cell caused by heat generation at the current moment.

[0122] In some embodiments, the specific formula for determining the temperature change amount inside the battery cell caused by heat generation at the current moment is as follows:

[0123] dT in_gen =Q / C in (4)

[0124] In formula (4), dT in_gen represents the temperature change amount inside the battery cell caused by heat generation at the current moment; Q represents the heat generation inside the battery cell at the current moment, for example, it can be the heat generation Q1 determined by formula (2) or the heat generation Q2 determined by formula (3); C in represents the heat capacity inside the battery cell.

[0125] In other words, taking Figure 1Taking the middle battery pack including cell A, cell C, and cell B as an example, determine whether cell A, cell C, and cell B adopt the first heat generation model or the second heat generation model respectively, and then perform heat generation calculations according to the determined heat generation models of each cell. When the cell is determined to adopt the first heat generation model, the heat generation Q inside the cell at the current moment can be calculated by formula (2); when the cell is determined to adopt the second heat generation model, the heat generation Q inside the cell at the current moment can be calculated by formula (3). Based on the heat generation Q determined for each cell respectively and the heat capacity C inside each cell in , determine the temperature change amount dT caused by heat generation inside each cell at the current moment in_gen .

[0126] Figure 7 The flowchart shows how to determine the temperature change amount of the equivalent point inside the cell at the current moment caused by heat transfer from other equivalent points in the point set according to some embodiments of the present application. The following will be combined with Figure 7 to specifically introduce how to determine the temperature change amount of the equivalent point inside the cell at the current moment caused by heat transfer from other equivalent points in the point set

[0127] Step S241, based on the heat transfer model corresponding to each cell, determine each heat transfer factor characterizing the heat transfer of other equivalent points to the equivalent point inside each cell at the current moment

[0128] Figure 8 The flowchart shows how to determine each heat transfer factor characterizing the heat transfer of other equivalent points to the equivalent point inside the cell at the current moment according to some embodiments of the present application. The following will be combined with Figure 8 to specifically introduce how to determine each heat transfer factor characterizing the heat transfer of other equivalent points to the equivalent point inside the cell at the current moment

[0129] Step S2411, based on the heat transfer model corresponding to each cell, determine the heat transfer rate, heat transfer distance from any other equivalent point in the point set to the equivalent point inside each cell, and the heat capacity inside each cell

[0130] It should be noted that when the battery pack includes only one cell, the point set includes the equivalent point inside the cell, the equivalent point of the positive electrode tab, the equivalent point of the negative electrode tab, and the equivalent point of the contact between the external heat source or cold source and the cell; when the battery pack includes multiple cells (for example Figure 1 the three cells shown), the point set includes the equivalent point inside the cell, the equivalent point of the positive electrode tab, the equivalent point of the negative electrode tab, the equivalent point of the contact between the external heat source or cold source and the cell, and the equivalent point of the contact between the adjacent cell and this cell

[0131] Step S2412: Based on the heat transfer rate, heat transfer distance, heat capacity inside the battery cell, and a preset period, determine the heat transfer factor at the current moment that characterizes the heat transfer from any other equivalent point to the equivalent point inside each battery cell.

[0132] In some embodiments, the heat transfer factor at the current moment that characterizes the heat transfer from any other equivalent point to the equivalent point inside the battery cell can be specifically determined by the following formula:

[0133] K M2N = λ M2N * L M2N / C N * dt (5)

[0134] In formula (5), K M2N represents the heat transfer factor from any other equivalent point M in the point set to the equivalent point N inside the battery cell; λ M2N represents the heat transfer rate from any other equivalent point M in the point set to the equivalent point N inside the battery cell, with the unit of W / (m*K); L M2N represents the heat transfer distance from any other equivalent point M in the point set to the equivalent point N inside the battery cell, with the unit of m; C N represents the heat capacity of the equivalent point N inside the battery cell, with the unit of J / degc; dt represents the preset period, with the unit of s.

[0135] Step S242: Based on the temperatures of the equivalent points in the point set at the previous moment and the heat transfer factors at the current moment that characterize the heat transfer from other equivalent points to the equivalent point inside each battery cell, determine the temperature change amount of the equivalent point inside each battery cell at the current moment due to the heat transfer from other equivalent points in the point set.

[0136] In some embodiments, the temperature change amount of the equivalent point N inside the battery cell at the current moment due to the heat transfer from other equivalent point M in the point set can be determined by the following formula:

[0137] dT M2N = -(T M - T N ) * K M2N (6)

[0138] In formula (6), dT M2N represents the temperature change amount of the equivalent point N inside the battery cell at the current moment due to the heat transfer from other equivalent point M in the point set; T M represents the temperature of other equivalent point M in the point set at the previous moment; T N represents the temperature of the equivalent point N inside the battery cell at the previous moment; K M2N represents the heat transfer factor from any other equivalent point M in the point set to the equivalent point N inside the battery cell.

[0139] In other words, taking a battery pack including three battery cells as shown in Figure 1 as an example, the simplified point set of battery cell C includes the equivalent points inside the battery cell of battery cell C, the equivalent points of the positive electrode tab of battery cell C, the equivalent points of the negative electrode tab of battery cell C, the equivalent points at the contact between the external heat source or cold source and battery cell C, and the equivalent points at the contact between the adjacent battery cells (battery cells A and B) and battery cell C. That is, the equivalent point N inside the battery cell of battery cell C will be affected by the heat transfer from the equivalent points of the positive electrode tab of battery cell C, the equivalent points of the negative electrode tab of battery cell C, the equivalent points at the contact between the external heat source or cold source and battery cell C, the equivalent points at the contact between the adjacent battery cell A and battery cell C, and the equivalent points at the contact between the adjacent battery cell B and battery cell C, resulting in a temperature change. The specific temperature change amount can be determined by the above formula (6). Similarly, the temperature change amount caused by heat transfer of battery cell A and the temperature change amount caused by heat transfer of battery cell B can be obtained. The difference from battery cell C is that there is only one adjacent battery cell, i.e., battery cell C.

[0140] In some embodiments, in step 25, determining the temperature inside each battery cell at the current moment can specifically be through the following formula:

[0141] T k = T k-1 + dT in_gen + dT M2N (7)

[0142] In formula (7), T k represents the temperature inside the battery cell at the current moment; T k-1 represents the temperature inside the battery cell at the previous moment; dT in_gen represents the temperature change amount caused by heat generation inside the battery cell at the current moment; dT M2N represents the temperature change amount caused by the heat transfer from other equivalent point M in the point set to the equivalent point N inside the battery cell at the current moment.

[0143] Similarly, based on a method similar to the above for determining the temperature inside the battery, the temperatures of other equivalent points in the point set can be determined with reference to the above method.

[0144] Figure 9 FIG. shows a flowchart for determining the temperature of each equivalent point in the point set at the current moment according to some embodiments of the present application. The following will specifically introduce how to determine the temperature of each equivalent point in the point set at the current moment. Figure 9 Specifically introduce how to determine the temperature of each equivalent point in the point set at the current moment.

[0145] When the external heat source or cold source is a solid medium, step S91 is executed to determine, based on the current current, thermal resistance, heat capacity, and preset period at the corresponding current moment, the temperature change amounts caused by heat generation at the positive electrode tab of each battery cell, the negative electrode tab of each battery cell, and the contact between the external heat source or cold source and each battery cell at the current moment.

[0146] In some embodiments, the external heat source or cold source can be a heating film or other solid medium.

[0147] In some embodiments, the temperature change amount caused by heat generation at the positive electrode tab of the battery cell at the current moment can be specifically determined by the following formula:

[0148] dT pos_gen =I 2 *R pos *dt / C pos (8)

[0149] In formula (8), dT pos_gen represents the temperature change amount caused by heat generation at the positive electrode tab of the battery cell at the current moment; I represents the current value of the battery cell at the current moment (i.e., the real-time collected current value); R pos represents the thermal resistance of the positive electrode tab; dt represents the preset period; C pos represents the heat capacity of the positive electrode tab.

[0150] Similarly, the temperature change amount caused by heat generation at the negative electrode tab of the battery cell at the current moment can be specifically determined by the following formula:

[0151] dT neg_gen =I 2 *R neg *dt / C neg (9)

[0152] In formula (9), dT neg_gen represents the temperature change amount caused by heat generation at the negative electrode tab of the battery cell at the current moment; I represents the current value of the battery cell at the current moment (i.e., the real-time collected current value); R neg represents the thermal resistance of the negative electrode tab; dt represents the preset period; C neg represents the heat capacity of the negative electrode tab.

[0153] Similarly, the temperature change amount caused by heat generation at the contact between the external heat source or cold source and the battery cell at the current moment can be specifically determined by the following formula:

[0154] dT source_gen =I 2 *R source *dt / C source (10)

[0155] In formula (10), dT source_gen represents the temperature change caused by heat generation of the external heat source or cold source at the current moment; I represents the current value of the battery cell at the current moment (i.e., the real-time collected current value); R source represents the thermal resistance of the external heat source or cold source; dt represents the preset period; C source represents the heat capacity of the external heat source or cold source.

[0156] Step S92: Based on the heat transfer model corresponding to each battery cell, respectively determine the equivalent points of the positive electrode tabs of each battery cell, the equivalent points of the negative electrode tabs of each battery cell, and the equivalent points at the contact between the external heat source or cold source and each battery cell due to the heat transfer from the equivalent points inside each battery cell, which cause temperature changes.

[0157] For the heat transfer calculation of the equivalent points of the positive electrode tabs of the battery cell, the equivalent points of the negative electrode tabs of the battery cell, and the equivalent points at the contact between the external heat source or cold source and the battery cell, since they only contact the inside of the battery cell, only the heat transfer with the inside of the battery cell needs to be considered. The specific calculation formula can refer to formula (6). It should be noted that since the heat capacity C N inside the battery cell is different from the heat capacity C pos of the positive electrode tab of the battery cell, the heat capacity C neg of the negative electrode tab of the battery cell, and the heat capacity C source of the external heat source or cold source, so K M2N is different from K N2M . Therefore, when calculating the temperature changes caused by the heat transfer of the equivalent points of the positive electrode tabs of the battery cell, the equivalent points of the negative electrode tabs of the battery cell, and the equivalent points at the contact between the external heat source or cold source and the battery cell with the equivalent point N inside the battery cell respectively, K M2N should be replaced with its corresponding K N2M in formula (6).

[0158] Step S93: Based on the temperature at the corresponding previous moment, the temperature change caused by heat generation at the current moment, and the temperature change caused by heat transfer, respectively determine the temperatures of the positive electrode tabs of each battery cell, the negative electrode tabs of each battery cell, and the contact between the external heat source or cold source and each battery cell at the current moment.

[0159] The specific calculation method for the temperatures of the positive electrode tabs of the battery cell, the negative electrode tabs of the battery cell, and the contact between the external heat source or cold source and the battery cell at the current moment can refer to formula (7).

[0160] It should be noted that when the external heat source or cold source is a fluid medium and the flow rate is greater than a preset threshold (fast flow rate), the above method is not required. Based on the temperature of the water outlet at the current moment, the temperature of the water inlet at the current moment, and the position of the battery cell relative to the external heat source or cold source, the temperature of the external heat source or cold source at the current moment can be determined. The temperature calculations for the positive electrode tab and the negative electrode tab of the battery cell remain unchanged. Please refer to the description in the case where the external heat source or cold source is a solid medium above.

[0161] In some embodiments, when the sleep duration of the battery cell is greater than or equal to a preset sleep duration (for example, 6 hours), based on the temperature at the temperature sampling point of the battery management system, the initial value of the internal temperature of the battery cell is determined. If there is no temperature sampling point, then the temperature of the adjacent sampling point can be directly used as the initial value of the internal temperature of the battery cell, or calculated based on the temperature of the adjacent sampling point, and the calculated temperature is used as the initial value of the internal temperature of the battery cell. And / or, when the sleep duration of the battery cell is less than the preset sleep duration (for example, 6 hours), based on the internal temperature of the battery cell before the previous power-off as the internal temperature of the battery cell at the previous moment and the sleep duration as the preset period, the initial value of the internal temperature of the battery cell is determined. In other words, the temperature obtained by performing a calculation with the sleep duration as the preset period dt in the above formula is used as the initial value of the internal temperature of the battery cell.

[0162] Figure 10 Shows a flowchart of closed-loop correction provided according to some embodiments of the present application. In some embodiments, as Figure 10 shown, the method for online determining the internal temperature of the battery pack further includes the following steps:

[0163] Step S101, when the temperature sampling point of the battery management system is located at the positive electrode tab and / or the negative electrode tab of any battery cell, determine whether the difference between the temperature of the temperature sampling point and the corresponding positive electrode tab and / or negative electrode tab of the determined battery cell is greater than the sum of the sampling temperature error and the preset threshold and lasts for a preset duration. Wherein, the preset duration can be at the minute level.

[0164] Step S102: When it is determined that the difference between the temperature of the temperature sampling point and the corresponding positive and / or negative electrode tabs of the determined battery cell is greater than the sum of the sampling temperature error and the preset threshold and lasts for a preset duration, the parameters are corrected. The correction points for closed-loop correction are the parameters or states that are more likely to have errors (or are prone to follow the changes in the battery cell state) and are easy to correct. In some embodiments, the parameters include the heat transfer factors of each equivalent point where any other equivalent point in the point set transfers heat to the inside of the battery cell and / or the initial temperature inside the battery cell. It should be noted that the closed-loop correction needs to be based on the temperatures of the temperature sampling points (such as the positive and / or negative electrode tabs) before and after a period of time corresponding to the moment when the difference is greater than the sum of the sampling temperature error and the preset threshold, and the temperatures determined by the above method.

[0165] Step S103: Based on the corrected parameters, re-determine the temperatures inside the battery cell, at the positive electrode tab, at the negative electrode tab, and at the contact between the external heat source or cold source and the battery cell in the past time period. Exemplarily, based on the corrected parameters, with the goal of minimizing the variance between the temperature of the temperature sampling point and the calculated temperature, perform closed-loop correction to re-determine the temperatures inside the battery cell, at the positive electrode tab, at the negative electrode tab, and at the contact between the external heat source or cold source and the battery cell in the past time period. Reset the current state with the corrected temperatures of each point and parameters. The corrected parameters are only used for the current power-on calculation, and when the correction is started again this time, it should tend to modify the corrected parameters.

[0166] This application also provides a battery management system, including: a processor and a memory, with a computer program stored on the memory, and the processor is used to execute the computer program to implement the method for online determining the temperature inside the battery pack in any one of the above embodiments.

[0167] The method for online determining the temperature inside the battery pack and the battery management system provided by this application have the following technical effects: (1) Since the heat generation model can switch between two models, the purpose of smaller errors is achieved; (2) The heat generation model and the heat transfer model consider the electrode tabs separately, so that the temperature of the sampling point can be on or near the electrode tabs, and thus the temperature inside the battery cell determined by online calculation can be made more accurate through closed-loop correction; (3) The external heat transfer model considers multiple points, and its accuracy and robustness are higher than those of the heat transfer model that only considers one point on the outer surface; the closed-loop correction method in the calculation process considers multiple correction methods, which can improve the accuracy of the temperature calculation inside the battery cell.

[0168] Figure 11 The block diagram of a SoC (System on Chip) provided according to some embodiments of this application is shown. In Figure 11 it, similar components have the same reference numerals. Additionally, the dashed box is an optional feature of a more advanced SoC. In Figure 11Among them, the SoC 1500 includes: an interconnect unit 1550, which is coupled to the application processor 1515; a system agent unit 1570; a bus controller unit 1580; an integrated memory controller unit 1540; one or a group of one or more coprocessors 1520, which may include integrated graphics logic, an image processor, an audio processor, and a video processor; a static random access memory (SRAM) unit 1530; and a direct memory access (DMA) unit 1560. In one embodiment, the coprocessor 1520 includes a dedicated processor, such as, for example, a network or communication processor, a compression engine, a GPGPU, a high-throughput MIC processor, or an embedded processor, and so on.

[0169] Embodiments of the mechanisms disclosed in this application can be implemented in hardware, software, firmware, or a combination of these implementation methods. Embodiments of this application can be implemented as a computer program or program code executed on a programmable system, which includes at least one processor, a storage system (including volatile and non-volatile memories and / or storage elements), at least one input device, and at least one output device.

[0170] The program code can be applied to the input instructions to perform the various functions described in this application and generate output information. The output information can be applied to one or more output devices in a known manner. For the purposes of this application, the processing system includes any system having a processor such as, for example, a digital signal processor (DSP), a microcontroller, an application-specific integrated circuit (ASIC), or a microprocessor.

[0171] The program code can be implemented in a high-level procedural language or an object-oriented programming language to communicate with the processing system. When necessary, the program code can also be implemented in assembly language or machine language. In fact, the mechanisms described in this application are not limited to the scope of any specific programming language. In any case, the language can be a compiled language or an interpreted language.

[0172] In some cases, the disclosed embodiments may be implemented in hardware, firmware, software, or any combination thereof. The disclosed embodiments may also be implemented as instructions carried or stored on one or more transitory or non-transitory machine-readable (e.g., computer-readable) storage media, which may be read and executed by one or more processors. For example, the instructions may be distributed via a network or via other computer-readable media. Thus, machine-readable media may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer), including but not limited to, floppy disks, optical disks, optical discs, CD-ROMs, magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, flash memory, or tangible machine-readable memories for transmitting information (e.g., carrier waves, infrared signals, digital signals, etc.) in electrical, optical, acoustic, or other forms via the Internet. Thus, machine-readable media include any type of machine-readable media suitable for storing or transmitting electronic instructions or information in a form readable by a machine (e.g., a computer).

[0173] In the drawings, some structural or method features may be shown in a particular arrangement and / or order. However, it should be understood that such a particular arrangement and / or ordering may not be required. Rather, in some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. Additionally, the inclusion of a structural or method feature in a particular figure does not imply that such a feature is required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0174] It should be noted that each unit / module mentioned in the device embodiments of the present application is a logical unit / module. Physically, a logical unit / module may be a physical unit / module, a part of a physical unit / module, or may be implemented as a combination of multiple physical units / module. The physical implementation manner of these logical units / module themselves is not the most important. The combination of the functions implemented by these logical units / module is the key to solving the technical problems proposed by the present application. In addition, in order to highlight the innovative part of the present application, the above device embodiments of the present application do not introduce units / modules that are not closely related to solving the technical problems proposed by the present application. This does not mean that there are no other units / modules in the above device embodiments.

[0175] It should be noted that in the examples and description of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one" does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0176] Each method embodiment of the present application can be implemented in ways such as software, magnetic components, firmware, etc.

[0177] The program code can be applied to the input instructions to perform the various functions described herein and generate output information. The output information can be applied to one or more output devices in a known manner. For the purposes of the present application, a processing system includes any system having a processor such as, for example, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), or a microprocessor.

[0178] The program code can be implemented in a high-level procedural language or an object-oriented programming language to communicate with the processing system. When needed, the program code can also be implemented in assembly language or machine language. In fact, the mechanisms described herein are not limited to the scope of any particular programming language. In any case, the language can be a compiled language or an interpreted language.

[0179] One or more aspects of at least one embodiment can be implemented by representative instructions stored on a computer-readable storage medium, the instructions representing various logics in a processor, and the instructions, when read by a machine, cause the machine to fabricate the logics for performing the techniques described herein. These representations, referred to as "IP cores", can be stored on a tangible computer-readable storage medium and provided to multiple customers or production facilities to be loaded into the manufacturing machines that actually fabricate the logics or processors.

[0180] In some cases, an instruction converter may be used to convert instructions from a source instruction set to a target instruction set. For example, the instruction converter may transform (e.g., using static binary translation, dynamic binary translation including dynamic compilation), morph, emulate, or otherwise convert an instruction into one or more other instructions to be processed by the IP core. The instruction converter may be implemented in software, hardware, firmware, or a combination thereof. The instruction converter may be on the processor, off the processor, or partly on the processor and partly off the processor.

[0181] Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, those of ordinary skill in the art should understand that various changes in form and detail may be made therein without departing from the spirit and scope of the present application.

Claims

1. A method for online determining the internal temperature of a battery pack, wherein the battery pack comprises one or more battery cells, wherein the battery cell comprises a battery cell interior, a positive electrode tab and a negative electrode tab, wherein: include: Determine a heat generation model of each battery cell in the battery pack at the current moment; Based on the heat generation model determined for each battery cell, determining a temperature change caused by heat generation inside the battery cell at a current moment; Based on the simplified point set of each battery cell, a corresponding heat transfer model is established, wherein the point set includes at least an equivalent point inside the battery cell, an equivalent point of the positive electrode tab, an equivalent point of the negative electrode tab, and an equivalent point at which an external heat source or cold source contacts the battery cell; Based on the heat transfer model corresponding to each battery cell, determining the temperature change of an equivalent point inside each battery cell at the current moment caused by heat transfer from other points in the point set; The temperature inside the battery cell at the previous moment, the temperature change inside the battery cell caused by heat generation at the current moment, and the temperature change at the equivalent point inside the battery cell at the current moment caused by heat transfer from other points in the point set, determine the temperature inside each battery cell at the current moment.

2. The method for online determining the internal temperature of a battery pack according to claim 1, characterized in that: The heat generation model includes a first heat generation model and a second heat generation model, the first heat generation model and the second heat generation model are different, and the step of determining the heat generation model of each battery cell in the battery pack at the current moment includes: Determine whether the absolute value of the current, the absolute value of the current rate, or the absolute value of the polarization voltage of each battery cell at the current moment is less than the corresponding preset threshold; When it is determined that the current absolute value, the current rate absolute value or the polarization voltage absolute value of each battery cell at the current moment is less than the corresponding preset threshold value, determining that each battery cell adopts the first heat generation model; and / or, Determine whether each battery cell is a lithium iron phosphate battery cell or a lithium iron manganese phosphate battery cell when it is determined that the absolute value of the current, the absolute value of the current rate or the absolute value of the polarization voltage of each battery cell at the current moment is not less than the corresponding preset threshold value; When it is determined that each battery cell is a lithium iron phosphate battery cell or a lithium iron manganese phosphate battery cell, determining whether the state of charge of each battery cell at a current moment is in a platform area, wherein the platform area is configured as an area where the open circuit voltage of the battery cell is not affected by the state of charge of the battery cell; When it is determined that the state of charge of each battery cell is in the platform area, determining that each battery cell adopts the second heat generation model; and / or, When it is determined that each battery cell is not a lithium iron phosphate battery cell or a lithium iron manganese phosphate battery cell or when it is determined that the state of charge of each battery cell is not in the platform area, respectively determine a first maximum error of each battery cell using the first heat generation model and a second maximum error of the second heat generation model; When the first maximum error is less than or equal to the second maximum error, determining that each battery cell adopts the first heat generation model; When the first maximum error is greater than the second maximum error, it is determined that each battery cell adopts the second heat generation model.

3. The method for online determining the internal temperature of a battery pack according to claim 2, characterized in that: The step of respectively determining a first maximum error of each battery cell using the first heat generation model and a second maximum error of the second heat generation model when it is determined that each battery cell is not a lithium iron phosphate battery cell and a lithium iron manganese phosphate battery cell or when it is determined that the state of charge of each battery cell is not in the platform area includes: Determine the state of charge of each battery cell at the current moment; Determine a rate of change of an open circuit voltage of each battery cell with respect to the state of charge of the battery cell based on the state of charge of each battery cell at a current moment and the temperature inside the battery cell of each battery cell at a previous moment; Determining a maximum value of the rate of change of the open circuit voltage with the state of charge of the battery cell based on the rate of change of the open circuit voltage of each battery cell with the state of charge of the battery cell; Based on the absolute value of the polarization voltage of each battery cell, determining the minimum value of the absolute value of the polarization voltage; Determining the first maximum error of the first heat generation model based on the maximum value of the rate of change of the open circuit voltage with the state of charge of the battery cell, the minimum value of the absolute value of the polarization voltage, a preset estimation accuracy of the state of charge of each battery cell, and a preset voltage sampling error; and / or, Determine a minimum value of the temperature inside the battery cell based on the temperature inside the battery cell of each battery cell at the previous moment; Based on the minimum value of the temperature inside the battery cell and a preset mapping relationship between temperature and error, a second maximum error of the second heat generation model is determined.

4. The method for online determining the internal temperature of a battery pack according to claim 3, characterized in that: The step of determining the temperature change caused by heat generation inside each battery cell at the current moment based on the heat generation model determined for each battery cell includes: When it is determined that each battery cell adopts the first heat generation model, based on the current of each battery cell at the current moment, the equivalent resistance of each battery cell, the temperature inside each battery cell at the previous moment, the rate of change of the open circuit voltage of each battery cell with the temperature, and a preset period, determine the heat generation inside the battery cell at the current moment; and / or, When it is determined that each battery cell adopts the second heat generation model, based on the polarization voltage of each battery cell at the current moment, the temperature inside each battery cell at the previous moment, the rate of change of the open circuit voltage of each battery cell with the temperature, the current of each battery cell at the current moment, and the preset period, determine the heat generation inside each battery cell at the current moment; Based on the heat generation inside each battery cell at the current moment and the heat capacity of each battery cell, the temperature change amount caused by the heat generation inside each battery cell at the current moment is determined.

5. The method for online determining the internal temperature of a battery pack according to claim 1, characterized in that: Also includes: In the case where the external heat source or cold source is a solid medium, based on the current, thermal resistance, thermal capacity and preset cycle at the corresponding current moment, the temperature change caused by heat generation at the positive electrode tab of each battery cell, the negative electrode tab of each battery cell and the contact between the external heat source or cold source and each battery cell at the current moment is determined respectively; Based on the heat transfer model corresponding to each battery cell, respectively determine the temperature change caused by heat transfer from the equivalent point inside the battery cell of each battery cell at the current moment at the equivalent point of the positive electrode tab of each battery cell, the equivalent point of the negative electrode tab of each battery cell, and the equivalent point at which the external heat source or cold source contacts each battery cell; Based on the corresponding temperature at the previous moment, the temperature change caused by heat generation and the temperature change caused by heat transfer at the current moment, respectively determine the temperature of the positive electrode tab of each battery cell, the negative electrode tab of each battery cell and the contact point between the external heat source or cold source and each battery cell at the current moment; The temperature of the positive electrode tab of each battery cell, the negative electrode tab of each battery cell, and the contact point between the external heat source or cold source and each battery cell at the current moment are respectively used as the temperature of the corresponding equivalent point at the current moment; and / or, When the external heat source or cold source is a fluid medium and the flow rate is greater than a preset threshold, the temperature of the point where the external heat source or cold source contacts each battery cell at the current moment is determined based on the water outlet temperature at the current moment, the water inlet temperature at the current moment, and the position of the battery cell relative to the external heat source or cold source.

6. The method for online determining the internal temperature of a battery pack according to claim 5, characterized in that: The battery pack includes a plurality of cells, the point set includes equivalent points inside the cell, equivalent points of the positive electrode tab, equivalent points of the negative electrode tab, equivalent points at which an external heat source or cold source contacts the cell, and equivalent points at which an adjacent cell contacts the cell, and the step of determining, based on the heat transfer model corresponding to each cell, a temperature change amount caused by heat transfer from other equivalent points in the point set at the current moment at an equivalent point inside each cell, comprises: Based on the heat transfer model corresponding to each battery cell, determining each heat transfer factor characterizing heat transfer from other equivalent points to an equivalent point inside each battery cell at the current moment; Based on the temperature of each equivalent point in the point set at the previous moment and the heat transfer factors that characterize the heat transfer from other equivalent points to the equivalent points inside each battery cell at the current moment, determine the temperature change of the equivalent points inside each battery cell at the current moment due to heat transfer from other equivalent points in the point set.

7. The method for online determining the internal temperature of a battery pack according to claim 6, characterized in that: The step of determining, based on the heat transfer model corresponding to each battery cell, each heat transfer factor characterizing heat transfer from other equivalent points to equivalent points inside each battery cell at the current moment comprises: Based on the heat transfer model corresponding to each battery cell, determine the heat transfer rate and heat transfer distance from any other equivalent point in the point set to the equivalent point inside the battery cell of each battery cell, and the heat capacity inside the battery cell of each battery cell; The heat transfer factor characterizing heat transfer from any other equivalent point to an equivalent point inside each battery cell at the current moment is determined based on the heat transfer rate, the heat transfer distance, the heat capacity inside each battery cell and the preset period.

8. The method for online determining the internal temperature of a battery pack according to claim 6, characterized in that: When the sleep time of each battery cell is greater than or equal to the preset sleep time, determining an initial value of the temperature inside each battery cell based on the temperature of a temperature sampling point of the battery management system; and / or, When the sleep time of each battery cell is less than the preset sleep time, the initial value of the internal temperature of each battery cell is determined based on the temperature inside the battery cell of each battery cell before the last power-off as the temperature inside the battery cell of each battery cell at the last moment and the sleep time as the preset period.

9. The method for online determining the internal temperature of a battery pack according to claim 8, characterized in that: Also includes: In the case where the temperature sampling point of the battery management system is located at the positive electrode tab and / or the negative electrode tab of any battery cell, determining whether the difference between the temperature of the temperature sampling point and the corresponding positive electrode tab and / or the negative electrode tab of each battery cell is greater than the sum of the sampling temperature error and a preset threshold value and lasts for a preset time; When it is determined that the difference between the temperature of the temperature sampling point and the corresponding positive electrode tab and / or the negative electrode tab of each battery cell is greater than the sum of the sampling temperature error and the preset threshold value for a preset period of time, the parameters are corrected, and the parameters include the heat transfer factors of the equivalent points of the battery cell of each battery cell transferred from any other equivalent point in the point set to the battery cell of each battery cell and / or the initial temperature value of the battery cell of each battery cell are corrected; Based on the corrected parameters, the temperatures of the interior of each battery cell, the positive electrode tab, the negative electrode tab, and the contact point between the external heat source or cold source and each battery cell in the past time period are re-determined.

10. A battery management system, characterized in that: include: A processor and a memory, wherein a computer program is stored in the memory, and the processor is used to execute the computer program to implement the method for online determining the internal temperature of a battery pack according to any one of claims 1 to 9.

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