Battery pack series arc risk evaluation method based on dynamic and static fusion

Abstract

The invention provides a dynamic and static fusion battery pack series arc risk evaluation method, and belongs to the technical field of battery safety, and the dynamic and static fusion battery pack series arc risk evaluation method comprises the steps: obtaining a voltage-current relational expression of different lengths of stable series arcs, and constructing a curved surface diagram; constructing arc discharge process dynamic characteristic functions and curved surface diagrams under different battery pack configurations; determining an intersection curve of the stable arc dynamic characteristic curved surface and the arc discharge process dynamic characteristic curved surface, and analyzing and quantifying arc occurrence probabilities and consequence danger characteristics configured by different battery packs; an arc fault risk level is determined by integrating the probability and the result quantitative characteristics; the invention provides a dynamic and static fusion battery pack series arc risk evaluation method, which can solve the problem that the current arc fault safety technology lacks systematic evaluation on arc fault risks.

Description

Technical Field

[0001] The present invention belongs to the field of battery safety technology, and in particular relates to a dynamic and static fusion battery pack series arc risk assessment method. Background Art

[0002] Lithium-ion batteries have been widely used in electric vehicles, electrochemical energy storage, and other fields. During the use of battery packs, arc faults may occur due to poor connections, insulation damage, or design defects. Arc faults not only degrade battery pack performance but can also cause safety hazards such as fires. Due to the effects of line impedance, the loop current of a series arc fault is reduced to below normal operating levels, making it difficult for conventional protection devices such as alarms, circuit breakers, and fuses to effectively detect and troubleshoot such faults. Furthermore, AC arcs differ from DC arcs in their characteristics. DC arcs do not produce intermittent periodic phenomena due to phase changes, and their current does not have a zero crossing point. Therefore, once a DC fault arc occurs, it is difficult to extinguish itself.

[0003] Current arc fault safety technologies primarily focus on detection and early warning, such as identification based on electrical signal characteristics and detection algorithms based on extensive historical operating data. However, these methods primarily focus on real-time detection and identification of arc faults, lacking a systematic assessment of arc fault risks. Summary of the Invention

[0004] In view of this, the present invention provides a dynamic and static fusion battery pack series arc risk assessment method, which can solve the problem that the current arc fault safety technology lacks a systematic assessment of arc fault risks.

[0005] The present invention is achieved in that:

[0006] The present invention provides a dynamic and static fusion battery pack series arc risk assessment method, which includes the following specific steps:

[0007] S10: Obtain the voltage-current relationship of stable series arcs of different lengths and construct a surface plot;

[0008] S20: Construct dynamic characteristic functions and surface diagrams of arcing process under different battery pack configurations;

[0009] S30: Determine the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyze and quantify the arc occurrence probability and consequence hazard characteristics of different battery pack configurations;

[0010] S40: Determine the arc fault risk level based on the combined probability and consequence quantitative characteristics.

[0011] On the basis of the above technical solution, the dynamic and static fusion battery pack series arc risk assessment method of the present invention can also be improved as follows:

[0012] The specific steps of obtaining the voltage-current relationship of stable series arcs of different lengths and constructing a surface graph include:

[0013] The first step is to measure and record the voltage and current data of stable arcs of different lengths, including the changes in arc current at different voltages, by conducting arc simulation experiments or literature research.

[0014] In the second step, the voltage-current relationship of different arc lengths is obtained by fitting the above data. The arc length, arc current and voltage are integrated to construct a surface diagram reflecting the dynamic characteristics of the stable arc.

[0015] Furthermore, the specific steps of fitting the voltage-current relationship of different arc lengths using the above data are as follows:

[0016] The voltage and current data of stable arcs of different lengths are input into data plotting software such as OriginPro 2021 or Matlab R2021a, and the voltage-current relationship of different arc lengths is obtained by iterative convergence through fitting the power function.

[0017] Furthermore, the constructed surface graph reflecting the dynamic characteristics of the stable arc has the current as the x-axis, the arc length as the y-axis, and the voltage as the z-axis.

[0018] Furthermore, the surface diagram reflecting the dynamic characteristics of the stable arc is fitted in the y-axis direction using a linear method.

[0019] Furthermore, the specific steps of constructing the dynamic characteristic function and surface diagram of the arc drawing process under different battery pack configurations are:

[0020] In the first step, during the arc starting process of the series arc, the current decreases from the normal operating current to 0, and the voltage increases from 0 to the voltage of the series battery string, thereby determining the dynamic characteristic function of the arcing process;

[0021] In the second step, the dynamic characteristic function of the arcing process of different battery pack configurations is input into data drawing software such as OriginPro 2021 or Matlab R2021a to obtain the voltage-current relationship; the arc length dimension is added, with current as the x-axis, arc length as the y-axis, and voltage as the z-axis, to construct a three-dimensional surface graph reflecting the dynamic characteristics of arcing.

[0022] Furthermore, the specific steps of determining the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyzing and quantifying the arc occurrence probability and consequence hazard characteristics of different battery pack configurations include:

[0023] The first step is to obtain the projection of the intersection line of the two surfaces on the arc distance and current plane;

[0024] The second step is to determine the probability of arc occurrence;

[0025] The third step is to use the current and corresponding voltage of the intersection curve of the two surfaces to retain only the points with larger current for the repeated current values of the same arc length, that is, the current value of the maximum arc distance of the projected curve is used as the boundary;

[0026] The fourth step is to calculate the average arc power in the larger current area and use it as a quantitative feature of the arc consequence hazard.

[0027] Furthermore, the specific steps of obtaining the projection of the intersection line of the two curved surfaces on the arc distance and current plane include:

[0028] In Matlab R2021a software, the steady-state arc characteristic surface and the dynamic arc characteristic surface are defined respectively. The global grid is divided according to the current and arc length range and encrypted at the intersection of the curves. The surface intersection line is obtained through tolerance detection and deduplication processing.

[0029] Furthermore, the probability of arc occurrence is determined based on the maximum value of the projection curve distance in the arc length direction.

[0030] Furthermore, the specific steps of determining the arc fault risk level by integrating the probability and consequence quantification characteristics include:

[0031] The first step is to calculate the quantitative characteristics of arc risk for different battery pack configurations;

[0032] The second step is to classify the risk levels according to the arc risk characteristic values of different battery pack configurations, providing a reference for battery pack arc prevention and control and emergency strategies.

[0033] Compared with the prior art, the dynamic and static fusion battery pack series arc risk assessment method provided by the present invention has the following beneficial effects:

[0034] (1) The present invention combines the arc occurrence probability and arc hazard of battery packs with different configurations, and comprehensively considers the arc risk analysis to obtain the quantitative characteristics of arc risks under different battery packs and different working conditions. At the same time, the critical conditions for the occurrence of steady-state arc faults can be obtained. It is suitable for battery packs with different configurations and has strong systematicity. The obtained battery pack arc risk results can provide a reference for arc prevention and control and emergency strategies for battery packs with different configurations.

[0035] (2) The present invention converts the complex arcing characteristics of battery packs with different structures into the form of surface intersection lines by constructing the current-voltage dynamic surfaces of stable arcs of different lengths and the current-voltage dynamic surfaces of the arcing process of series battery packs. Compared with the experimental and numerical simulation methods, the calculation efficiency is greatly improved, and the quantitative classification of the probability of arc occurrence and the harmfulness of the consequences is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of a dynamic and static fusion battery pack series arc risk assessment method of the present invention;

[0037] Figure 2 This is a schematic diagram of the surface intersection curve in Example 2 of a dynamic and static fusion battery pack series arc risk assessment method of the present invention;

[0038] Figure 3 The intersection curve in the second embodiment of the dynamic and static fusion battery pack series arc risk assessment method of the present invention is projected on the current-arc length plane;

[0039] Figure 4 This is a schematic diagram of the surface intersection curve in Example 3 of a dynamic and static fusion battery pack series arc risk assessment method of the present invention;

[0040] Figure 5 The intersection curve in Example 3 of the dynamic and static fusion battery pack series arc risk assessment method of the present invention is projected on the current-arc length plane;

[0041] Figure 6 This is a schematic diagram of the surface intersection curve in Example 4 of a dynamic and static fusion battery pack series arc risk assessment method of the present invention;

[0042] Figure 7 This is the projection of the intersection curve in the current-arc length plane in Example 4 of the dynamic and static fusion battery pack series arc risk assessment method of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0044] like Figure 1 FIG. 1 shows a first embodiment of a dynamic and static fusion battery pack series arc risk assessment method provided by the present invention. In this embodiment, the following specific steps are included:

[0045] S10: Obtain the voltage-current relationship of stable series arcs of different lengths and construct a surface plot;

[0046] S20: Construct dynamic characteristic functions and surface diagrams of arcing process under different battery pack configurations;

[0047] S30: Determine the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyze and quantify the arc occurrence probability and consequence hazard characteristics of different battery pack configurations;

[0048] S40: Determine the arc fault risk level based on the combined probability and consequence quantitative characteristics.

[0049] Among them, in the above technical solution, the specific steps of obtaining the voltage-current relationship of stable series arcs of different lengths and constructing a surface graph include:

[0050] The first step is to measure and record the voltage and current data of stable arcs of different lengths, including the changes in arc current at different voltages, by conducting arc simulation experiments or literature research.

[0051] In the second step, the voltage-current relationship of different arc lengths is obtained by fitting the above data. The arc length, arc current and voltage are integrated to construct a surface diagram reflecting the dynamic characteristics of the stable arc.

[0052] Furthermore, in the above technical solution, the specific steps of fitting the above data to obtain the voltage-current relationship for different arc lengths are as follows:

[0053] The voltage and current data of stable arcs of different lengths are input into data plotting software such as OriginPro 2021 or Matlab R2021a, and the voltage-current relationship of different arc lengths is obtained by iterative convergence through fitting the power function.

[0054] Furthermore, in the above technical solution, the surface diagram constructed to reflect the dynamic characteristics of the stable arc has the current as the x-axis, the arc length as the y-axis, and the voltage as the z-axis.

[0055] Furthermore, in the above technical solution, a linear method is used to fit the surface diagram reflecting the dynamic characteristics of the stable arc in the y-axis direction.

[0056] Furthermore, in the above technical solution, the specific steps of constructing the dynamic characteristic function and surface diagram of the arcing process under different battery pack configurations are as follows:

[0057] In the first step, during the arc starting process of the series arc, the current decreases from the normal operating current to 0, and the voltage increases from 0 to the voltage of the series battery string. The dynamic characteristic function of the arcing process is determined as follows:

[0058]

[0059] Among them, U bis the real-time voltage of the battery cell, n is the number of batteries in series, I w is the real-time current of the battery string, U arc , I arc are arc voltage and current respectively;

[0060] In the second step, the dynamic characteristic function of the arcing process of different battery pack configurations is input into data drawing software such as OriginPro 2021 or Matlab R2021a to obtain the voltage-current relationship; the arc length dimension is added, with current as the x-axis, arc length as the y-axis, and voltage as the z-axis, to construct a three-dimensional surface graph reflecting the dynamic characteristics of arcing.

[0061] Furthermore, in the above technical solution, the specific steps of determining the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyzing and quantifying the arc occurrence probability and consequence hazard characteristics of different battery pack configurations include:

[0062] The first step is to obtain the projection of the intersection line of the two surfaces on the arc distance and current plane;

[0063] The second step is to determine the probability of arc occurrence;

[0064] The third step is to use the current and corresponding voltage of the intersection curve of the two surfaces to retain only the points with larger current for the repeated current values of the same arc length, that is, the current value of the maximum arc distance of the projected curve is used as the boundary;

[0065] The fourth step is to calculate the average arc power in the larger current area and use it as a quantitative characteristic of the arc consequence hazard:

[0066]

[0067] Where m is the maximum current value of the projection curve, and n is the current value at the maximum arc distance of the projection curve.

[0068] Furthermore, in the above technical solution, the specific steps of obtaining the projection of the intersection line of the two curved surfaces on the arc distance and current plane include:

[0069] In Matlab R2021a software, the steady-state arc characteristic surface and the dynamic arc characteristic surface are defined respectively. The global grid is divided according to the current and arc length range and encrypted at the intersection of the curves. The surface intersection line is obtained through tolerance detection and deduplication processing.

[0070] Furthermore, in the above technical solution, the probability of arc occurrence is determined based on the maximum value of the projection curve distance in the arc length direction.

[0071] Furthermore, in the above technical solution, the specific steps of determining the arc fault risk level by integrating the probability and consequence quantitative characteristics include:

[0072] The first step is to calculate the quantitative characteristics of arc risk for different battery pack configurations:

[0073]

[0074] Where S is the arc risk quantitative characteristic value, L max The maximum arc distance under different battery pack configurations, that is, the quantified value of the arc occurrence probability.

[0075] The second step is to classify the risk levels according to the arc risk characteristic values of different battery pack configurations, providing a reference for battery pack arc prevention and control and emergency strategies.

[0076] In addition, this technical solution can also achieve the following additional functions:

[0077] The steady-state arc characteristic curve established in step S10 is combined with the dynamic characteristic curve of the battery pack arcing process established in step S20 to determine whether there is a zero point in the difference between the two curves. Based on the result, the critical conditions and characteristics of steady-state arcing under different battery pack configurations and operating conditions can be obtained. If there is an intersection, the conditions for a steady-state arc fault exist, and the voltage and current at this intersection are the voltage and current of the steady-state arc. If there is no intersection, a steady-state arc fault will not occur.

[0078] like Figure 2-3 , is a second embodiment of a dynamic and static fusion battery pack series arc risk assessment method provided by the present invention, and in this embodiment, includes the following specific steps:

[0079] S10: Obtain the voltage-current relationship of stable series arcs of different lengths and construct a surface plot;

[0080] S20: Construct dynamic characteristic functions and surface diagrams of arcing process under different battery pack configurations;

[0081] S30: Determine the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyze and quantify the arc occurrence probability and consequence hazard characteristics of different battery pack configurations;

[0082] S40: Determine the arc fault risk level based on the combined probability and consequence quantitative characteristics.

[0083] Among them, in the above technical solution, the specific steps of obtaining the voltage-current relationship of stable series arcs of different lengths and constructing a surface graph include:

[0084] The first step is to measure and record the voltage and current data of stable arcs of different lengths, including the changes in arc current at different voltages, by conducting arc simulation experiments or literature research.

[0085] Among them, through literature research, the stable arc current-voltage changes at lengths of 1, 5, 10, 20, and 50 mm were collected, as shown in Table 1;

[0086] Table 1 Steady-state arc characteristic parameters

[0087]

[0088] In the second step, the voltage-current relationship of different arc lengths is obtained by fitting the above data. The arc length, arc current and voltage are integrated to construct a surface diagram reflecting the dynamic characteristics of the stable arc.

[0089] Furthermore, in the above technical solution, the specific steps of fitting the above data to obtain the voltage-current relationship for different arc lengths are as follows:

[0090] The voltage and current data of stable arcs of different lengths are input into data plotting software such as OriginPro 2021 or Matlab R2021a, and the voltage-current relationship of different arc lengths is obtained by iterative convergence through fitting the power function.

[0091] like Figure 2 As shown, further, in the above technical solution, the surface diagram reflecting the dynamic characteristics of the stable arc is constructed with current as the x-axis, arc length as the y-axis, and voltage as the z-axis.

[0092] Furthermore, in the above technical solution, a linear method is used to fit the surface diagram reflecting the dynamic characteristics of the stable arc in the y-axis direction.

[0093] Furthermore, in the above technical solution, the specific steps of constructing the dynamic characteristic function and surface diagram of the arcing process under different battery pack configurations are as follows:

[0094] In the first step, during the arcing process of the series arc, the current decreases from the normal operating current to 0, and the voltage increases from 0 to the voltage of the series battery string. Taking a battery pack of 10 280Ah lithium iron phosphate energy storage batteries in series as an example, when the battery is fully charged (3.65V per cell) and discharged at a current of 0.5C (140A), the dynamic characteristic function of the arcing process is determined as follows:

[0095]

[0096] Among them, U arc , I arc are arc voltage and current respectively;

[0097] In the second step, the dynamic characteristic function of the arcing process of different battery pack configurations is input into data drawing software such as OriginPro 2021 or Matlab R2021a to obtain the voltage-current relationship; the arc length dimension is added, with current as the x-axis, arc length as the y-axis, and voltage as the z-axis, to construct a three-dimensional surface graph reflecting the dynamic characteristics of arcing.

[0098] Furthermore, in the above technical solution, the specific steps of determining the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyzing and quantifying the arc occurrence probability and consequence hazard characteristics of different battery pack configurations include:

[0099] The first step, such as Figure 3 As shown, the projection of the intersection line of the two surfaces on the arc distance and current plane is obtained;

[0100] The second step is to determine the probability of arc occurrence;

[0101] like Figure 3 The projected curves depict the currents generated by series arcs of varying lengths for this embodiment's battery pack configuration. Therefore, the arc length reflects the range within which a series arc may occur; a larger value indicates a greater likelihood of an arc fault. The maximum arc length in the projected curve is used as the arc occurrence probability. In this embodiment, the maximum arc length is 1.7 mm.

[0102] The third step is to use the current and corresponding voltage of the intersection curve of the two surfaces to retain only the points with larger current for the repeated current values of the same arc length, that is, the current value of the maximum arc distance of the projected curve is used as the boundary;

[0103] The fourth step is to calculate the average arc power in the larger current area and use it as a quantitative characteristic of the arc consequence hazard:

[0104]

[0105] Where m is the maximum current value of the projection curve, and n is the current value at the maximum arc distance of the projection curve.

[0106] Furthermore, in the above technical solution, the specific steps of obtaining the projection of the intersection line of the two curved surfaces on the arc distance and current plane include:

[0107] In Matlab R2021a software, the steady-state arc characteristic surface and the dynamic arc characteristic surface are defined respectively. The global grid is divided according to the current and arc length range and encrypted at the intersection of the curves. The surface intersection line is obtained through tolerance detection and deduplication processing.

[0108] Furthermore, in the above technical solution, the probability of arc occurrence is determined based on the maximum value of the projection curve distance in the arc length direction.

[0109] Furthermore, in the above technical solution, the specific steps of determining the arc fault risk level by integrating the probability and consequence quantitative characteristics include:

[0110] The first step is to calculate the arc risk value for the battery pack configuration using the following formula based on the calculated probability of arc occurrence and the quantitative value of dangerous consequences of the battery pack series connection:

[0111]

[0112] Where S is the arc risk quantitative characteristic value, L max The maximum arc distance under different battery pack configurations, that is, the quantified value of the arc occurrence probability.

[0113] In the second step, the arc risk values under different battery pack configurations are calculated through the above steps, and a comprehensive risk level evaluation can be performed. The arc risk values are graded according to Table 2.

[0114] Table 2 Risk classification of battery pack series arc fault

[0115]

[0116] The larger the risk value S, the greater the probability of occurrence and the dangerous consequences of a series arc fault under this battery pack configuration. When designing battery pack safety, it is necessary to make corresponding arc prevention and control settings according to different risk levels to ensure that when a series arc fault occurs, there are sufficient protection measures to quickly cut off the fault and avoid irreversible serious consequences.

[0117] like Figure 4-5 , is a third embodiment of a dynamic and static fusion battery pack series arc risk assessment method provided by the present invention. In this embodiment, the following specific steps are included:

[0118] S10: Obtain the voltage-current relationship of stable series arcs of different lengths and construct a surface plot;

[0119] S20: Construct dynamic characteristic functions and surface diagrams of arcing process under different battery pack configurations;

[0120] S30: Determine the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyze and quantify the arc occurrence probability and consequence hazard characteristics of different battery pack configurations;

[0121] S40: Determine the arc fault risk level based on the combined probability and consequence quantitative characteristics.

[0122] Among them, in the above technical solution, the specific steps of obtaining the voltage-current relationship of stable series arcs of different lengths and constructing a surface graph include:

[0123] The first step is to measure and record the voltage and current data of stable arcs of different lengths, including the changes in arc current at different voltages, by conducting arc simulation experiments or literature research.

[0124] Among them, through literature research, the stable arc current-voltage changes at lengths of 1, 5, 10, 20, and 50 mm were collected, as shown in Table 1;

[0125] In the second step, the voltage-current relationship of different arc lengths is obtained by fitting the above data. The arc length, arc current and voltage are integrated to construct a surface diagram reflecting the dynamic characteristics of the stable arc.

[0126] Furthermore, in the above technical solution, the specific steps of fitting the above data to obtain the voltage-current relationship for different arc lengths are as follows:

[0127] The voltage and current data of stable arcs of different lengths are input into data plotting software such as OriginPro 2021 or Matlab R2021a, and the voltage-current relationship of different arc lengths is obtained by iterative convergence through fitting the power function.

[0128] like Figure 4 As shown, further, in the above technical solution, the surface diagram reflecting the dynamic characteristics of the stable arc is constructed with current as the x-axis, arc length as the y-axis, and voltage as the z-axis.

[0129] Furthermore, in the above technical solution, a linear method is used to fit the surface diagram reflecting the dynamic characteristics of the stable arc in the y-axis direction.

[0130] Furthermore, in the above technical solution, the specific steps of constructing the dynamic characteristic function and surface diagram of the arcing process under different battery pack configurations are as follows:

[0131] In the first step, during the arcing process of the series arc, the current decreases from the normal operating current to 0, and the voltage increases from 0 to the voltage of the series battery string. Taking a battery pack of 20 280Ah lithium iron phosphate energy storage batteries in series as an example, when the battery is fully charged (3.65V per cell) and discharged at a current of 1C (280A), the dynamic characteristic function of the arcing process is determined as follows:

[0132]

[0133] Among them, U arc , I arc are arc voltage and current respectively;

[0134] In the second step, the dynamic characteristic function of the arcing process of different battery pack configurations is input into data drawing software such as OriginPro 2021 or Matlab R2021a to obtain the voltage-current relationship; the arc length dimension is added, with current as the x-axis, arc length as the y-axis, and voltage as the z-axis, to construct a three-dimensional surface graph reflecting the dynamic characteristics of arcing.

[0135] Furthermore, in the above technical solution, the specific steps of determining the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyzing and quantifying the arc occurrence probability and consequence hazard characteristics of different battery pack configurations include:

[0136] The first step, such as Figure 5 As shown, the projection of the intersection line of the two surfaces on the arc distance and current plane is obtained;

[0137] The second step is to determine the probability of arc occurrence;

[0138] like Figure 5 The projected curve shows the current behavior of series arcs of varying lengths for this embodiment's battery pack configuration. Therefore, the arc length reflects the range within which a series arc may occur; a larger value indicates a greater likelihood of an arc fault. The maximum arc length in the projected curve is used as the arc occurrence probability. In this embodiment, the maximum arc length is 29.9 mm.

[0139] The third step is to use the current and corresponding voltage of the intersection curve of the two surfaces to retain only the points with larger current for the repeated current values of the same arc length, that is, the current value of the maximum arc distance of the projected curve is used as the boundary;

[0140] The fourth step is to calculate the average arc power in the larger current area and use it as a quantitative characteristic of the arc consequence hazard:

[0141]

[0142] Where m is the maximum current value of the projection curve, and n is the current value at the maximum arc distance of the projection curve.

[0143] Furthermore, in the above technical solution, the specific steps of obtaining the projection of the intersection line of the two curved surfaces on the arc distance and current plane include:

[0144] In Matlab R2021a software, the steady-state arc characteristic surface and the dynamic arc characteristic surface are defined respectively. The global grid is divided according to the current and arc length range and encrypted at the intersection of the curves. The surface intersection line is obtained through tolerance detection and deduplication processing.

[0145] Furthermore, in the above technical solution, the probability of arc occurrence is determined based on the maximum value of the projection curve distance in the arc length direction.

[0146] Furthermore, in the above technical solution, the specific steps of determining the arc fault risk level by integrating the probability and consequence quantitative characteristics include:

[0147] The first step is to calculate the arc risk value for the battery pack configuration using the following formula based on the calculated probability of arc occurrence and the quantitative value of dangerous consequences of the battery pack series connection:

[0148]

[0149] Where S is the arc risk quantitative characteristic value, L max The maximum arc distance under different battery pack configurations, that is, the quantified value of the arc occurrence probability.

[0150] In the second step, the arc risk values under different battery pack configurations are calculated through the above steps, and a comprehensive risk level evaluation can be performed. The arc risk values are graded according to Table 2.

[0151] The larger the risk value S, the greater the probability of occurrence and the dangerous consequences of a series arc fault under this battery pack configuration. When designing battery pack safety, it is necessary to make corresponding arc prevention and control settings according to different risk levels to ensure that when a series arc fault occurs, there are sufficient protection measures to quickly cut off the fault and avoid irreversible serious consequences.

[0152] Compared with Example 2, the battery pack voltage and operating current of this embodiment are both increased to twice the original ones. The analysis results show that the arc risk level is greatly increased. Therefore, arc prevention and control measures with higher protection levels should be adopted to reduce the probability of arc faults or respond to and cut off the corresponding faults in a timely manner.

[0153] like Figure 6-7 , is the fourth embodiment of a dynamic and static fusion battery pack series arc risk assessment method provided by the present invention. The invention is applicable to various system batteries. This embodiment is described using a ternary lithium-ion battery as an example;

[0154] In this embodiment, the following specific steps are included:

[0155] S10: Obtain the voltage-current relationship of stable series arcs of different lengths and construct a surface plot;

[0156] S20: Construct dynamic characteristic functions and surface diagrams of arcing process under different battery pack configurations;

[0157] S30: Determine the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyze and quantify the arc occurrence probability and consequence hazard characteristics of different battery pack configurations;

[0158] S40: Determine the arc fault risk level based on the combined probability and consequence quantitative characteristics.

[0159] Among them, in the above technical solution, the specific steps of obtaining the voltage-current relationship of stable series arcs of different lengths and constructing a surface graph include:

[0160] The first step is to measure and record the voltage and current data of stable arcs of different lengths, including the changes in arc current at different voltages, by conducting arc simulation experiments or literature research.

[0161] Among them, through literature research, the stable arc current-voltage changes at lengths of 1, 5, 10, 20, and 50 mm were collected, as shown in Table 1;

[0162] In the second step, the voltage-current relationship of different arc lengths is obtained by fitting the above data. The arc length, arc current and voltage are integrated to construct a surface diagram reflecting the dynamic characteristics of the stable arc.

[0163] Furthermore, in the above technical solution, the specific steps of fitting the above data to obtain the voltage-current relationship for different arc lengths are as follows:

[0164] The voltage and current data of stable arcs of different lengths are input into data plotting software such as OriginPro 2021 or Matlab R2021a, and the voltage-current relationship of different arc lengths is obtained by iterative convergence through fitting the power function.

[0165] like Figure 6 As shown, further, in the above technical solution, the surface diagram reflecting the dynamic characteristics of the stable arc is constructed with current as the x-axis, arc length as the y-axis, and voltage as the z-axis.

[0166] Furthermore, in the above technical solution, a linear method is used to fit the surface diagram reflecting the dynamic characteristics of the stable arc in the y-axis direction.

[0167] Furthermore, in the above technical solution, the specific steps of constructing the dynamic characteristic function and surface diagram of the arcing process under different battery pack configurations are as follows:

[0168] In the first step, during the arcing process of the series arc, the current decreases from the normal operating current to 0, and the voltage increases from 0 to the voltage of the series battery string. Taking a battery pack of 10 120Ah lithium iron phosphate energy storage batteries in series as an example, when the battery is fully charged (4.2V per cell) and discharged at a current of 1C (120A), the dynamic characteristic function of the arcing process is determined as follows:

[0169]

[0170] Among them, U arc, I arc are arc voltage and current respectively;

[0171] In the second step, the dynamic characteristic function of the arcing process of different battery pack configurations is input into data drawing software such as OriginPro 2021 or Matlab R2021a to obtain the voltage-current relationship; the arc length dimension is added, with current as the x-axis, arc length as the y-axis, and voltage as the z-axis, to construct a three-dimensional surface graph reflecting the dynamic characteristics of arcing.

[0172] Furthermore, in the above technical solution, the specific steps of determining the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyzing and quantifying the arc occurrence probability and consequence hazard characteristics of different battery pack configurations include:

[0173] The first step, such as Figure 7 As shown, the projection of the intersection line of the two surfaces on the arc distance and current plane is obtained;

[0174] The second step is to determine the probability of arc occurrence;

[0175] like Figure 7 The projected curves depict the currents generated by series arcs of varying lengths for this embodiment's battery pack configuration. Therefore, the arc length reflects the range within which a series arc may occur; a larger value indicates a greater likelihood of an arc fault. The maximum arc length in the projected curve is used as the arc occurrence probability. In this embodiment, the maximum arc length is 3.5 mm.

[0176] The third step is to use the current and corresponding voltage of the intersection curve of the two surfaces to retain only the points with larger current for the repeated current values of the same arc length, that is, the current value of the maximum arc distance of the projected curve is used as the boundary;

[0177] The fourth step is to calculate the average arc power in the larger current area and use it as a quantitative characteristic of the arc consequence hazard:

[0178]

[0179] Where m is the maximum current value of the projection curve, and n is the current value at the maximum arc distance of the projection curve.

[0180] Furthermore, in the above technical solution, the specific steps of obtaining the projection of the intersection line of the two curved surfaces on the arc distance and current plane include:

[0181] In Matlab R2021a software, the steady-state arc characteristic surface and the dynamic arc characteristic surface are defined respectively. The global grid is divided according to the current and arc length range and encrypted at the intersection of the curves. The surface intersection line is obtained through tolerance detection and deduplication processing.

[0182] Furthermore, in the above technical solution, the probability of arc occurrence is determined based on the maximum value of the projection curve distance in the arc length direction.

[0183] Furthermore, in the above technical solution, the specific steps of determining the arc fault risk level by integrating the probability and consequence quantitative characteristics include:

[0184] The first step is to calculate the arc risk value for the battery pack configuration using the following formula based on the calculated probability of arc occurrence and the quantitative value of dangerous consequences of the battery pack series connection:

[0185]

[0186] Where S is the arc risk quantitative characteristic value, L max The maximum arc distance under different battery pack configurations, that is, the quantified value of the arc occurrence probability.

[0187] In the second step, the arc risk values under different battery pack configurations are calculated through the above steps, and a comprehensive risk level evaluation can be performed. The arc risk values are graded according to Table 2.

[0188] Compared to Example 2, this embodiment uses ternary lithium-ion batteries. The cell voltage is higher, and therefore the battery pack voltage is increased, which promotes arcing. The operating current is lower than in Example 2, which inhibits arcing. Combining these two effects, the final arc risk value is slightly higher than that of Example 2, which is reasonable.

[0189] Specifically, the principle of the present invention is: when in use, the voltage-current relationship of stable series arcs of different lengths is obtained, and a surface diagram is constructed; the dynamic characteristic function and surface diagram of the arcing process under different battery pack configurations are constructed; the intersection curve of the dynamic characteristic surface of the stable arc and the dynamic characteristic surface of the arcing process is determined, and the probability of arc occurrence and the dangerous characteristics of the consequences of different battery pack configurations are analyzed and quantified; the probability and consequence quantification characteristics are combined to determine the arc fault risk level.

[0190] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A dynamic and static fusion battery pack series arc risk assessment method, characterized in that: The specific steps include: S10: Obtain the voltage-current relationship of stable series arcs of different lengths and construct a surface plot; S20: Construct dynamic characteristic functions and surface diagrams of arcing process under different battery pack configurations; S30: Determine the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyze and quantify the arc occurrence probability and consequence hazard characteristics of different battery pack configurations; S40: Determine the arc fault risk level based on the combined probability and consequence quantitative characteristics.

2. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 1 is characterized in that: The specific steps of obtaining the voltage-current relationship of stable series arcs of different lengths and constructing a surface graph include: The first step is to measure and record the voltage and current data of stable arcs of different lengths, including the changes in arc current at different voltages, by conducting arc simulation experiments or literature research. In the second step, the voltage-current relationship of different arc lengths is obtained by fitting the above data. The arc length, arc current and voltage are integrated to construct a surface diagram reflecting the dynamic characteristics of the stable arc.

3. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 2 is characterized in that: The specific steps of fitting the voltage-current relationship of different arc lengths using the above data are as follows: The voltage and current data of stable arcs of different lengths are input into data plotting software such as OriginPro 2021 or Matlab R2021a, and the voltage-current relationship of different arc lengths is obtained by iterative convergence through fitting the power function.

4. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 3 is characterized in that: The constructed surface graph reflecting the dynamic characteristics of the stable arc has the current as the x-axis, the arc length as the y-axis, and the voltage as the z-axis.

5. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 4 is characterized in that: The surface diagram reflecting the dynamic characteristics of the stable arc is fitted in the y-axis direction using a linear method.

6. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 5 is characterized in that: The specific steps of constructing the dynamic characteristic function and surface diagram of the arc drawing process under different battery pack configurations are: In the first step, during the arc starting process of the series arc, the current decreases from the normal operating current to 0, and the voltage increases from 0 to the voltage of the series battery string, thereby determining the dynamic characteristic function of the arcing process; In the second step, the dynamic characteristic function of the arcing process of different battery pack configurations is input into data drawing software such as OriginPro 2021 or MatlabR2021a to obtain the voltage-current relationship; the arc length dimension is added, with current as the x-axis, arc length as the y-axis, and voltage as the z-axis, to construct a three-dimensional surface graph reflecting the dynamic characteristics of arcing.

7. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 6, characterized in that: The specific steps of determining the intersection curve of the stable arc dynamic characteristic surface and the arcing process dynamic characteristic surface, and analyzing and quantifying the arc occurrence probability and consequence hazard characteristics of different battery pack configurations include: The first step is to obtain the projection of the intersection line of the two surfaces on the arc distance and current plane; The second step is to determine the probability of arc occurrence; The third step is to use the current and corresponding voltage of the intersection curve of the two surfaces to retain only the points with larger current for the repeated current values of the same arc length, that is, the current value of the maximum arc distance of the projected curve is used as the boundary; The fourth step is to calculate the average arc power in the larger current area and use it as a quantitative feature of the arc consequence hazard.

8. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 7 is characterized in that: The specific steps of obtaining the projection of the intersection line of the two curved surfaces on the arc distance and current plane include: In Matlab R2021a software, the steady-state arc characteristic surface and the dynamic arc characteristic surface are defined respectively. The global grid is divided according to the current and arc length range and encrypted at the intersection of the curves. The surface intersection line is obtained through tolerance detection and deduplication processing.

9. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 8, characterized in that: The probability of arc occurrence is determined based on the maximum value of the projection curve distance in the arc length direction.

10. The method for evaluating arc risk of battery packs in series with dynamic and static fusion according to claim 9, characterized in that: The specific steps of determining the arc fault risk level by combining the probability and consequence quantitative characteristics include: The first step is to calculate the quantitative characteristics of arc risk for different battery pack configurations; The second step is to classify the risk levels according to the arc risk characteristic values of different battery pack configurations, providing a reference for battery pack arc prevention and control and emergency strategies.

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