Vehicle battery evaluation method and device

Abstract

The invention discloses a vehicle battery evaluation method and device, and belongs to the technical field of vehicle battery testing. A specific embodiment of the method comprises the following steps: controlling a vehicle battery to carry out pulse discharge under various current intensities, and monitoring the discharge voltage change of the vehicle battery in the pulse discharge process; for one current intensity, determining a voltage drop rate corresponding to the current intensity according to the discharge voltage change corresponding to the current intensity; furthermore, the maximum pulse discharge current is calculated for the vehicle battery by using the voltage drop rates corresponding to the various current intensities, so that the maximum pulse discharge capability of the vehicle battery is evaluated based on the maximum pulse discharge current (namely, the boundary discharge current which can be used for evaluating whether the aging of the battery is accelerated or not); according to the embodiment of the invention, the fineness and accuracy of evaluating the maximum pulse discharge capability are improved, and the complexity of testing and calculating the maximum pulse discharge current is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle battery testing, and in particular to a vehicle battery evaluation method and device. Background Art

[0002] In the use of new energy vehicles, the maximum pulse discharge capability of the battery is a key factor affecting the vehicle's power performance. Pulse discharge that exceeds the battery's own capacity may lead to problems such as accelerated aging of battery materials, rapid growth of battery internal resistance and rapid decrease in capacity. It may also bring about the risk of thermal runaway due to increased heat during battery use. Therefore, the requirements for the accuracy of determining the maximum pulse discharge current that indicates the maximum pulse discharge capability are becoming increasingly higher.

[0003] At present, the main method for evaluating the maximum pulse discharge capability of a battery is through the Hybrid Pulse Power Characterization (HPPC) test of vehicle batteries. This test determines the battery current corresponding to the cutoff voltage reached by the battery during the discharge process as the maximum pulse discharge current of the battery. The maximum pulse discharge current determined by the existing method cannot be used as the boundary discharge current for evaluating whether the battery will accelerate aging. There are problems with the low precision and high complexity of the maximum pulse discharge current indicating the maximum pulse discharge capability. Summary of the Invention

[0004] In view of this, the present invention provides a vehicle battery evaluation method and device, which can control the vehicle battery to perform pulse discharge under multiple current intensities and monitor the discharge voltage changes of the vehicle battery during the pulse discharge process; for a current intensity, according to the discharge voltage change corresponding to the current intensity, the voltage drop rate corresponding to the current intensity is determined; and the voltage drop rates corresponding to the multiple current intensities are used to calculate the maximum pulse discharge current for the vehicle battery, so as to evaluate the maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current (that is, the boundary discharge current that can be used to evaluate whether the battery will accelerate aging). The embodiments of the present invention improve the precision and accuracy of evaluating the maximum pulse discharge capability and reduce the complexity of testing and calculating the maximum pulse discharge current.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a vehicle battery evaluation method, comprising: controlling a vehicle battery to perform pulse discharge at multiple current intensities, and monitoring the discharge voltage change of the vehicle battery during the pulse discharge process; for one of the current intensity, determining the voltage drop rate corresponding to the current intensity based on the discharge voltage change corresponding to the current intensity; using the voltage drop rates corresponding to multiple current intensities to determine the maximum pulse discharge current of the vehicle battery, and evaluating the maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current.

[0007] Optionally, determining the maximum pulse discharge current of the vehicle battery includes: performing a linear fitting operation on data points indicating voltage drop rates corresponding to a plurality of current intensities, and determining the maximum pulse discharge current of the vehicle battery according to a result of the linear fitting operation.

[0008] Optionally, the vehicle battery evaluation method further includes: determining multiple battery test conditions for evaluating the vehicle battery; wherein the battery test conditions include: one or more external test environments and the remaining battery power; for each of the battery test conditions, respectively executing the steps of controlling the vehicle battery to perform pulse discharge at multiple current intensities and monitoring the discharge voltage changes of the vehicle battery during the pulse discharge process.

[0009] Optionally, determining the voltage drop rate corresponding to the current intensity includes: constructing a voltage-pulse time relationship curve for the vehicle battery based on the monitored discharge voltage change; calculating the voltage drop rate corresponding to the current intensity based on the voltage change trend indicated by the voltage-pulse time relationship curve; wherein, calculating the voltage drop rate corresponding to the current intensity includes: intercepting a segmented curve within a set pulse time range from the voltage-pulse time relationship curve; using the segmented voltage curve to indicate the voltage decline trend, calculating the slope corresponding to the segmented curve; and using the slope to indicate the voltage drop rate corresponding to the current intensity.

[0010] Optionally, the linear fitting operation is performed on the data points indicating the voltage drop rates corresponding to the multiple current intensities, including: placing the data points indicating the voltage drop rates corresponding to the multiple current intensities in a preset coordinate system indicating the relationship between the voltage change rate and the pulse discharge current; and performing iterative linear fitting on the data points in an ascending order of the data points indicating the voltage drop rates corresponding to the multiple current intensities in the coordinate system.

[0011] Optionally, the iterative linear fitting of the data points includes: for the first iteration cycle, starting from the data point indicated by the minimum voltage drop rate, selecting at least two data points in order from low to high, and performing linear fitting on the selected data points; for each iteration cycle other than the first iteration cycle, selecting the data points selected in the previous cycle, and selecting one or more data points in order from low to high, and performing linear fitting on the selected data points; after all data points are selected, stopping the iteration.

[0012] Optionally, the linear fitting of the selected data points further includes: calculating the fitting determination coefficient corresponding to each iteration cycle based on the data points selected in each iteration cycle; determining the maximum pulse discharge current of the vehicle battery based on the result of the linear fitting operation includes: when the fitting determination coefficient corresponding to any iteration cycle exceeds the set fitting coefficient threshold, and the fitting determination coefficient corresponding to the subsequent adjacent iteration cycle of the iteration cycle does not exceed the set fitting coefficient threshold, taking the current corresponding to the maximum data point in the iteration cycle as the maximum pulse discharge current.

[0013] In a second aspect, an embodiment of the present invention provides a vehicle battery evaluation device, comprising:

[0014] a discharge operation module, which is used to control the vehicle battery to perform pulse discharge at various current intensities and monitor the discharge voltage change of the vehicle battery during the pulse discharge process;

[0015] a voltage tracking module configured to determine, for a current intensity, a voltage drop rate corresponding to the current intensity based on a discharge voltage change corresponding to the current intensity;

[0016] A current evaluation module is configured to determine a maximum pulse discharge current of the vehicle battery by using voltage drop rates corresponding to a plurality of current intensities, and to evaluate a maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current.

[0017] Optionally, the vehicle battery evaluation device, for determining the maximum pulse discharge current of the vehicle battery, includes: performing a linear fitting operation on data points indicating voltage drop rates corresponding to multiple current intensities, and determining the maximum pulse discharge current of the vehicle battery based on the result of the linear fitting operation.

[0018] Optionally, the vehicle battery evaluation device is further used to determine multiple battery test conditions for evaluating the vehicle battery; wherein the battery test conditions include: one or more external test environments and the remaining battery power; for each of the battery test conditions, the steps of controlling the vehicle battery to perform pulse discharge at multiple current intensities and monitoring the discharge voltage changes of the vehicle battery during the pulse discharge process are performed respectively.

[0019] Optionally, the vehicle battery evaluation device is used to determine the voltage drop rate corresponding to the current intensity, including: constructing a voltage-pulse time relationship curve for the vehicle battery based on the monitored discharge voltage changes; calculating the voltage drop rate corresponding to the current intensity based on the voltage change trend indicated by the voltage-pulse time relationship curve; wherein, the calculation of the voltage drop rate corresponding to the current intensity includes: intercepting a segmented curve within a set pulse time range from the voltage-pulse time relationship curve; using the segmented voltage curve to indicate the voltage decline trend, calculating the slope corresponding to the segmented curve; using the slope to indicate the voltage drop rate corresponding to the current intensity.

[0020] Optionally, the vehicle battery evaluation device is used to perform a linear fitting operation on the data points indicating the voltage drop rate corresponding to multiple current intensities, including: placing the data points indicating the voltage drop rate corresponding to the multiple current intensities in a preset coordinate system indicating the relationship between the voltage change rate and the pulse discharge current; and iteratively linear fitting the data points in the order of the data points indicating the voltage drop rate corresponding to the multiple current intensities from low to high in the coordinate system.

[0021] Optionally, the vehicle battery evaluation device is used to perform iterative linear fitting on data points, including: for the first iteration cycle, starting from the data point indicated by the minimum voltage drop rate, selecting at least two data points in order from low to high, and performing linear fitting on the selected data points; for each iteration cycle other than the first iteration cycle, selecting the data points selected in the previous cycle, and selecting one or more data points in order from low to high, and performing linear fitting on the selected data points; after all data points are selected, stopping the iteration.

[0022] Optionally, the vehicle battery evaluation device is used to perform linear fitting on selected data points, further including: calculating the fitting determination coefficient corresponding to each iteration cycle based on the data points selected in each iteration cycle; determining the maximum pulse discharge current of the vehicle battery based on the result of the linear fitting operation includes: when the fitting determination coefficient corresponding to any iteration cycle exceeds the set fitting coefficient threshold, and the fitting determination coefficient corresponding to the subsequent adjacent iteration cycle of the iteration cycle does not exceed the set fitting coefficient threshold, using the current corresponding to the maximum data point in the iteration cycle as the maximum pulse discharge current.

[0023] In a third aspect, an embodiment of the present invention provides an electronic device, including:

[0024] one or more processors;

[0025] a storage device for storing one or more programs,

[0026] When the one or more programs are executed by the one or more processors, the one or more processors implement the vehicle battery evaluation method according to the embodiment of the present invention.

[0027] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium on which is stored a computer program for implementing a method for monitoring a vehicle battery status. When the computer program is executed by an onboard processor, the vehicle battery evaluation method of the embodiment of the present invention is implemented.

[0028] The technical solution of the above invention has the following advantages or beneficial effects: it can control the vehicle battery to perform pulse discharge under multiple current intensities and monitor the discharge voltage changes of the vehicle battery during the pulse discharge process; for a current intensity, according to the discharge voltage change corresponding to the current intensity, determine the voltage drop rate corresponding to the current intensity; and use the voltage drop rates corresponding to multiple current intensities to calculate the maximum pulse discharge current for the vehicle battery, so as to evaluate the maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current (that is, the boundary discharge current that can be used to evaluate whether the battery will accelerate aging). The embodiment of the present invention improves the precision and accuracy of evaluating the maximum pulse discharge capability and reduces the complexity of testing and calculating the maximum pulse discharge current. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of a vehicle battery evaluation method provided according to an embodiment of the present invention;

[0030] Figure 2 is a flow chart of another vehicle battery evaluation method provided according to an embodiment of the present invention;

[0031] Figure 32 is a schematic diagram of a voltage-pulse time relationship curve provided according to an embodiment of the present invention;

[0032] Figure 4A is a schematic diagram of the relationship between voltage change rate and pulse discharge current provided according to an embodiment of the present invention;

[0033] Figure 4B is a schematic diagram of another relationship between voltage change rate and pulse discharge current provided according to an embodiment of the present invention;

[0034] Figure 4C is a schematic diagram of another relationship between voltage change rate and pulse discharge current provided according to an embodiment of the present invention;

[0035] Figure 5 2 is a schematic structural diagram of a vehicle battery evaluation device provided according to an embodiment of the present invention;

[0036] Figure 6 It is a schematic diagram of the structure of a computer system suitable for implementing the embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following description of exemplary embodiments of the present invention is made in conjunction with the accompanying drawings, in which various details of the embodiments of the present invention are included to facilitate understanding. These details should be considered as merely exemplary. Therefore, it should be appreciated by those skilled in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0038] It should be pointed out that, in the absence of conflict, the embodiments of the present invention and the technical features therein may be combined with each other.

[0039] Furthermore, the terms "first," "second," and "third," etc., used in the embodiments of the present invention, are used to distinguish similar objects, and are not necessarily used to describe a specific number or order. It should be understood that such terms are interchangeable where appropriate, and are merely a means of distinguishing objects with the same attributes in the embodiments of the present invention.

[0040] Furthermore, the vehicle involved in the embodiment of the present invention may be an internal combustion engine vehicle using an engine as a power source, a hybrid vehicle using an engine and an electric motor as power sources, an electric vehicle using an electric motor as a power source, or the like.

[0041] Figure 1 A schematic diagram showing the main steps of the vehicle battery evaluation method provided by an embodiment of the present invention is shown:

[0042] Step S101: controlling a vehicle battery to perform pulse discharge at various current intensities, and monitoring a discharge voltage change of the vehicle battery during the pulse discharge process.

[0043] Specifically, in an embodiment of the present invention, under various test conditions, the vehicle battery is controlled to perform pulse discharge at various current intensities, for example: the battery is pulse discharged according to the current I (0.1C, 0.3C, 0.5C, 1C, 2C, etc.) from small to large, with a pulse time of t, until the pulse discharge current is large enough to make the battery voltage reach the lower limit voltage before the pulse time is reached; wherein, the battery unit "C" is used to represent the rate of the battery charge and discharge current; for example, if the rated capacity of the battery is 100Ah, 0.1C represents charging and discharging with a current of 10A.

[0044] Furthermore, multiple battery test conditions for evaluating the vehicle battery are determined; wherein the battery test conditions include: one or more of the external test environment and the remaining battery capacity. The external test environment includes one or more of temperature, humidity, pressure, etc.; the battery remaining capacity percentage (State of Charge, referred to as SOC) is, for example, 20%, 50%, 80%, etc. It can be understood that the battery remaining capacity percentage can be any value in the range of (0% to 100%). That is, multiple battery test conditions for evaluating the vehicle battery are determined; wherein the battery test conditions include: one or more of the external test environment and the remaining battery capacity; for each of the battery test conditions, the steps of controlling the vehicle battery to perform pulse discharge at multiple current intensities and monitoring the discharge voltage changes of the vehicle battery during the pulse discharge process are respectively executed; the refinement of the vehicle battery evaluation method is improved, thereby improving the accuracy of determining the maximum pulse discharge current.

[0045] By constructing different battery test conditions, the control of the vehicle battery to perform pulse discharge under multiple current intensities is executed respectively, and the maximum pulse discharge current of the vehicle battery under the battery test condition is determined, so that the maximum pulse discharge capacity of the vehicle battery under the test condition is evaluated based on the maximum pulse discharge current (that is, the boundary discharge current that can be used to evaluate whether the battery will accelerate aging), which further improves the precision and accuracy of evaluating the maximum pulse discharge capacity of the vehicle battery under different conditions and reduces the complexity of testing and calculating the maximum pulse discharge current.

[0046] Step S102: for one current intensity, determine a voltage drop rate corresponding to the current intensity according to a discharge voltage change corresponding to the current intensity.

[0047] Specifically, in a battery pulse discharge test, the discharge voltage change of the vehicle battery during the pulse discharge process is monitored; for one current intensity, the voltage drop rate corresponding to the current intensity is determined based on the discharge voltage change corresponding to the current intensity.

[0048] The method for determining the voltage drop rate corresponding to the current intensity includes: constructing a voltage-pulse time relationship curve for the vehicle battery based on the monitored discharge voltage change; and calculating the voltage drop rate corresponding to the current intensity based on the voltage change trend indicated by the voltage-pulse time relationship curve;

[0049] Furthermore, the calculation of the voltage drop rate corresponding to the current intensity includes: intercepting a segmented curve within a set pulse time range from the voltage-pulse time relationship curve; using the segmented voltage curve to indicate the downward trend of the voltage, and calculating the slope corresponding to the segmented curve; using the slope to indicate the voltage drop rate corresponding to the current intensity.

[0050] The following combination Figure 3 The schematic diagram shows the method of determining the voltage drop rate for a certain current intensity, such as Figure 3 In the coordinate system shown, the horizontal axis is the pulse time, for example, 10s; the vertical axis is the voltage; Figure 3 The voltage-pulse time relationship curve shown is obtained under the test conditions of SOC 20%, current intensity 1C, and ambient test temperature 25 degrees; Figure 3 As shown, as the pulse time increases, the voltage shows a downward trend; that is, the voltage change trend indicated by the voltage-pulse time relationship curve.

[0051] Furthermore, a segmented curve within the set pulse time range is intercepted from the voltage-pulse time relationship curve; Figure 3 As shown, for example, if the pulse time is 10s, a segmented curve between the pulse time [5s, 10s] is intercepted, assuming that the maximum voltage of the segmented curve is V1 and the minimum voltage is V2; further, the slope k corresponding to the segmented curve is calculated based on V1 and V2; the slope k is used to indicate the voltage drop rate corresponding to the current intensity of 1C. Among them, the set pulse time range can be calculated by [x*t, t], or the set pulse time range (for example, [5s, 10s], etc.) can be directly determined by experimental data, x represents the discharge current C, and t represents the pulse time; it can be understood that the set pulse time range can be obtained through multiple test data, so as to more accurately determine the slope k of the voltage drop through the set pulse time range; it can be understood that the pulse time corresponding to different current intensities can be different.

[0052] Furthermore, a voltage-pulse time relationship curve is constructed for the vehicle battery for different current intensities; a segmented curve within a set pulse time range is intercepted from the voltage-pulse time relationship curve according to the voltage change trend indicated by the voltage-pulse time relationship curve; and a slope corresponding to the segmented curve is calculated using the downward change trend of the voltage indicated by the segmented voltage curve, thereby obtaining voltage slopes corresponding to multiple current intensities under one test condition.

[0053] Step S103: Determine the maximum pulse discharge current of the vehicle battery using the voltage drop rates corresponding to the various current intensities, and evaluate the maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current.

[0054] Specifically, a linear fitting operation is performed on data points indicating voltage drop rates corresponding to a plurality of current intensities, and the maximum pulse discharge current of the vehicle battery is determined according to the result of the linear fitting operation.

[0055] Furthermore, the linear fitting operation is performed on the data points indicating the voltage drop rates corresponding to the multiple current intensities, including: placing the data points indicating the voltage drop rates corresponding to the multiple current intensities in a preset coordinate system indicating the relationship between the voltage change rate and the pulse discharge current; and performing iterative linear fitting on the data points in the order of the data points indicating the voltage drop rates corresponding to the multiple current intensities from low to high in the coordinate system.

[0056] Figures 4A to 4C The coordinate system of the preset voltage change rate (voltage drop slope)-pulse discharge current relationship is shown; and the data points indicated by the voltage drop rate (slope) placed in the voltage drop slope-pulse discharge current coordinate system; as shown in FIG. Figure 4A As shown in the figure, it shows that under the test conditions of SOC of 20% and temperature of 25 degrees, 7 data points in the coordinate system are obtained for 7 current intensities. Each data point is used to indicate the value of the voltage drop rate (voltage drop slope) corresponding to different current intensities (i.e. pulse discharge current); the 7 data points can be in order from low to high. Figure 4B As shown, it shows that under the test conditions of the vehicle battery with an SOC of 25% and a temperature of 25 degrees, 7 data points in the coordinate system are obtained for 7 current intensities; Figure 4C As shown, it shows that under the test conditions of the vehicle battery having an SOC of 80% and a temperature of 25 degrees, 8 data points in the coordinate system are obtained for 8 current intensities.

[0057] Furthermore, iterative linear fitting is performed on the data points according to the order of the data points indicating the voltage drop rates corresponding to the various current intensities from low to high in the coordinate system.

[0058] Specifically, iterative linear fitting of data points includes: for the first iteration cycle, starting from the data point indicated by the minimum voltage drop rate, selecting at least two data points in order from low to high, and performing linear fitting on the selected data points; for each iteration cycle other than the first iteration cycle, selecting the data points selected in the previous cycle, and selecting one or more data points in order from low to high, and performing linear fitting on the selected data points; after all data points are selected, stopping the iteration.

[0059] Furthermore, based on the data points selected in each iterative cycle, the fitting determination coefficient corresponding to each iterative cycle is calculated; the maximum pulse discharge current of the vehicle battery is determined based on the result of the linear fitting operation, including: when the fitting determination coefficient corresponding to any iterative cycle exceeds the set fitting coefficient threshold, and the fitting determination coefficient corresponding to the subsequent adjacent iterative cycle of the iterative cycle does not exceed the set fitting coefficient threshold, the current corresponding to the maximum data point in the iterative cycle is used as the maximum pulse discharge current.

[0060] Still Figure 4A For example, Figure 4A As shown in the figure, under the test conditions of 20% SOC and 25°C, seven data points in the coordinate system are obtained for seven current intensities. Furthermore, an iterative linear fit is performed on the data points. The linear fit is performed iteratively, including multiple iterations, to determine the maximum pulse discharge current.

[0061] Specifically, for the first iteration cycle, starting from the data point indicated by the minimum voltage drop rate, at least two data points are selected in order from low to high, and linear fitting is performed on the selected data points; for each iteration cycle other than the first iteration cycle, the data points selected in the previous cycle are selected, and one or more data points are selected in order from low to high, and linear fitting is performed on the selected data points; after all data points are selected, the iteration is stopped.

[0062] Furthermore, the corresponding fitting determination coefficient is calculated for each iteration cycle in the multiple iteration cycles, for example, Figure 4A R shown in 2 ; Among them, in the linear fitting, the coefficient R 2 Also known as the coefficient of determination, it is an important indicator used to measure the goodness of fit of a regression model. It indicates the proportion of the variation of the dependent variable that can be explained by the independent variable, and its value range is between 0 and 1. Figure 4A The data points in the equation are numbered 1 to 7 in order of voltage drop slope from low to high. Assume that the fitting determination coefficient R obtained in the iterative cycle of calculating data points 1 to 5 is 2=0.9943, calculate the fitting determination coefficient R obtained from data points 1 to 6 2 = 0.9774, calculate the fitting determination coefficient R obtained from data points 1 to 7 2 =0.9353; Assuming that the fitting coefficient threshold is set to 0.99, therefore, the fitting determination coefficient obtained in the iteration cycle of data points 1 to 5 is greater than 0.99 (the set fitting coefficient threshold) and the fitting determination coefficient obtained in the iteration cycle of data points 1 to 6 (i.e., the subsequent adjacent iteration cycle of iteration cycles 1 to 5) is less than 0.99, then the maximum data point (i.e., the boundary data point) in the iteration cycle of data points 1 to 5 is calculated as the maximum pulse discharge current; Figure 4A As shown, the pulse discharge current 4.5C (for example, expressed as Im=4.5C) corresponding to the fifth data point is the maximum pulse discharge current tested and calculated under the conditions of SOC of 20% and temperature of 25 degrees.

[0063] Similarly, Figure 4B The figure shows the linear fitting results of 7 data points indicating the voltage drop slope calculated under the conditions of SOC of 25% and temperature of 25 degrees. Figure 4B As shown, it is assumed that the fitting determination coefficient R is obtained in the iterative cycle of calculating data points 1 to 6. 2 =0.993, and the fitting determination coefficient R is obtained in the iterative cycle of data points 1 to 7. 2 =0.9817, the fitting determination coefficient obtained in the iterative cycle of data points 1 to 6 is greater than 0.99 (i.e., the set fitting coefficient threshold) and the fitting determination coefficient obtained in the iterative cycle of data points 1 to 7 (i.e., the subsequent adjacent iterative cycle of data points 1 to 6) is less than 0.99, then the pulse discharge current (5.79C) corresponding to the maximum data point in the iterative cycle of data points 1 to 6 is used as the maximum pulse discharge current; for example, it can be expressed as: Im = 5.79C. That is, if the fitting determination coefficient corresponding to any iterative cycle exceeds the set fitting coefficient threshold and the fitting determination coefficient corresponding to the subsequent adjacent iterative cycle of the iterative cycle does not exceed the set fitting coefficient threshold, the current corresponding to the maximum data point in the iterative cycle is used as the maximum pulse discharge current.

[0064] Similarly, Figure 4C The figure shows the linear fitting results of 8 data points indicating the voltage drop slope calculated under the conditions of SOC of 80% and temperature of 25 degrees, as shown in FIG. Figure 4C As shown, it is assumed that the fitting determination coefficient R obtained in the iterative cycle of calculating data points 1 to 7 is 2 =0.996, and the fitting determination coefficient R is obtained in the iterative cycle of data points 1 to 8. 2=0.9877. Therefore, if the fitting coefficient of determination obtained in the iterative cycle of data points 1 to 7 is greater than 0.99 (the set fitting coefficient threshold) and the fitting coefficient of determination obtained in the iterative cycle of data points 1 to 8 (i.e., the subsequent adjacent iterative cycle of data points 1 to 7) is less than 0.99, then the pulse discharge current (8.0C) corresponding to the maximum data point in the iterative cycle of data points 1 to 7 is used as the maximum pulse discharge current; expressed as: Im = 8.0C. That is, if the fitting coefficient of determination corresponding to any iterative cycle exceeds the set fitting coefficient threshold, and the fitting coefficient of determination corresponding to the subsequent adjacent iterative cycle of the iterative cycle does not exceed the set fitting coefficient threshold, the current corresponding to the maximum data point in the iterative cycle is used as the maximum pulse discharge current. It is acceptable that the fitting result obtained by linear fitting is optimal when the fitting coefficient of determination corresponding to any iterative cycle exceeds the set fitting coefficient threshold, and the fitting coefficient of determination corresponding to the subsequent adjacent iterative cycle of the iterative cycle does not exceed the set fitting coefficient threshold.

[0065] The embodiment of the present invention is as follows Figures 4A to 4C The schematic diagram shows a method for performing a linear fitting operation on data points indicating voltage drop rates corresponding to multiple current intensities, and determining the maximum pulse discharge current of the vehicle battery based on the results of the linear fitting operation, which improves the refinement of calculating the maximum pulse discharge current under different test conditions and the accuracy of the data. The traditional HPPC method of judging by cut-off voltage cannot evaluate whether the battery will accelerate aging, and requires a method of verifying the reliability of the battery in combination with a cycle test. Compared with the traditional method, the embodiment of the present invention greatly reduces the complexity of testing the maximum pulse discharge current, and can directly evaluate the maximum pulse discharge capability of the vehicle battery through the maximum pulse discharge current.

[0066] Figure 2 The following is a schematic diagram showing the main process of the vehicle battery evaluation method provided by the embodiment of the present invention:

[0067] Step S201: determining various battery test conditions for evaluating the vehicle battery, such as calibrating the battery capacity, adjusting the battery to the SOC state required for the test through charging / discharging according to the calibrated capacity, and setting the test environment temperature.

[0068] Step S202: Pulse discharge tests are performed on the battery with currents I (0.1C, 0.3C, 0.5C, 1C, 2C...) from small to large, with a pulse time of t, until the current is large enough to make the battery voltage reach the lower limit voltage before the pulse time is reached, and a curve of voltage change over time is recorded.

[0069] Specifically, the description of steps S201 to S202 is to determine multiple battery test conditions for evaluating the vehicle battery; wherein the battery test conditions include: one or more of the external test environment and the remaining battery power;

[0070] For each of the battery test conditions, the steps of controlling the vehicle battery to perform pulse discharge at multiple current intensities and monitoring the discharge voltage change of the vehicle battery during the pulse discharge process are performed respectively.

[0071] Furthermore, a voltage-pulse time relationship curve is constructed for the vehicle battery based on the monitored discharge voltage change; and a voltage drop rate corresponding to the current intensity is calculated based on the voltage change trend indicated by the voltage-pulse time relationship curve;

[0072] Step S203: intercepting the segmented curves of the voltage within the set pulse time interval [x*t, t] corresponding to different pulse current intensities, performing linear fitting, and obtaining the slope k indicating the voltage drop rate, wherein 0.1≤x<1.

[0073] Specifically, the description of step S203 is: intercepting a segmented curve within the set pulse time range ([x*t, t]) from the voltage-pulse time relationship curve; using the segmented voltage curve to indicate the downward trend of the voltage, and calculating the slope corresponding to the segmented curve; using the slope to indicate the voltage drop rate corresponding to the current intensity.

[0074] Step S204: With the pulse discharge current as the horizontal coordinate and the slope k as the vertical coordinate, a scatter plot of the data points of kI is drawn, and linear fitting is performed on the data points corresponding to different current intervals. In the current interval (0, Im], the linear fitting degree R 2 ≥0.99; while the linear fitting degree R 2 <0.99, where I>Im, then Im is the maximum pulse discharge current of the battery under this test condition.

[0075] Specifically, the description of step S204 is to place the data points indicating the voltage drop rate corresponding to various current intensities in a preset coordinate system indicating the relationship between the voltage change rate and the pulse discharge current (represented by I); and perform iterative linear fitting on the data points according to the order of the data points indicating the voltage drop rate corresponding to the various current intensities in the coordinate system from low to high.

[0076] Among them, the linear fitting operation is performed on the data points indicating the voltage drop rate corresponding to the multiple current intensities, including: placing the data points indicating the voltage drop rate corresponding to the multiple current intensities in a preset coordinate system indicating the relationship between the voltage change rate and the pulse discharge current; and iteratively linear fitting the data points according to the order of the data points indicating the voltage drop rate corresponding to the multiple current intensities in the coordinate system from low to high.

[0077] The iterative linear fitting of the data points includes: for the first iterative cycle, starting from the data point indicated by the minimum voltage drop rate, selecting at least two data points in order from low to high, and performing linear fitting on the selected data points; for each iterative cycle other than the first iterative cycle, selecting the data points selected in the previous cycle, and selecting one or more data points in order from low to high, and performing linear fitting on the selected data points; after all data points are selected, stopping the iteration.

[0078] The linear fitting of the selected data points further includes: calculating the fitting determination coefficient corresponding to each iteration cycle based on the data points selected in each iteration cycle; determining the maximum pulse discharge current of the vehicle battery based on the result of the linear fitting operation includes: when the fitting determination coefficient corresponding to any iteration cycle exceeds the set fitting coefficient threshold and the fitting determination coefficient corresponding to the subsequent adjacent iteration cycle of the iteration cycle does not exceed the set fitting coefficient threshold, using the current corresponding to the maximum data point in the iteration cycle as the maximum pulse discharge current.

[0079] Figure 5 A vehicle battery evaluation device 500 to which an embodiment of the present invention may be applied is shown, comprising:

[0080] a discharge operation module 501 for controlling the vehicle battery to perform pulse discharge at various current intensities and monitoring the discharge voltage change of the vehicle battery during the pulse discharge process;

[0081] a voltage tracking module 502 for determining, for a current intensity, a voltage drop rate corresponding to the current intensity based on a discharge voltage change corresponding to the current intensity;

[0082] The current evaluation module 503 is configured to determine the maximum pulse discharge current of the vehicle battery by using voltage drop rates corresponding to a plurality of current intensities, and to evaluate the maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current.

[0083] Reference below Figure 6 , which shows a schematic structural diagram of a computer system 600 suitable for implementing an embodiment of the present invention. Figure 6The computer system shown is only an example and should not limit the functions and scope of use of the embodiments of the present invention.

[0084] like Figure 6 As shown, the computer system 600 includes a central processing unit (CPU) 601, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage unit 608 into a random access memory (RAM) 603. Various programs and data required for the operation of the system 600 are also stored in the RAM 603. The CPU 601, ROM 602, and RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0085] The following components are connected to the I / O interface 605: an input section 606; an output section 607 including a cathode ray tube (CRT), a liquid crystal display (LCD), and a speaker; a storage section 608 including a hard disk; and a communication section 609 including a network interface card such as a LAN card or a modem. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the I / O interface 605 as needed. A removable medium 611, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, is installed in the drive 610 as needed, so that a computer program read therefrom can be installed in the storage section 608 as needed.

[0086] In particular, according to the embodiments disclosed in the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, the embodiments disclosed in the present invention include a computer program product comprising a computer program carried on a computer-readable medium, the computer program comprising program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 609, and / or installed from a removable medium 611. When the computer program is executed by the central processing unit (CPU) 601, the above-mentioned functions defined in the system of the present invention are performed.

[0087] It should be noted that the computer-readable medium described in the present invention can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media can include, but are not limited to, an electrical connection having one or more conductors, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In the present invention, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. This propagated data signal can take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in conjunction with an instruction execution system, apparatus, or device. Program code embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wireline, optical fiber cable, RF, or any suitable combination thereof.

[0088] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0089] As another aspect, the present invention further provides a computer-readable medium, which may be included in the device described in the above embodiment; or may exist independently and not be incorporated into the device. The computer-readable medium carries one or more programs, and when executed by a device, the device includes the following steps: controlling a vehicle battery to perform pulse discharge at multiple current intensities and monitoring the discharge voltage change of the vehicle battery during the pulse discharge process; determining, for one current intensity, a voltage drop rate corresponding to the current intensity based on the discharge voltage change corresponding to the current intensity; determining a maximum pulse discharge current of the vehicle battery using the voltage drop rates corresponding to the multiple current intensities, and evaluating the maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current.

[0090] The above specific implementation manner does not constitute a limitation on the protection scope of the present invention.

[0091] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A vehicle battery evaluation method, characterized in that: include: Controlling a vehicle battery to perform pulse discharge at various current intensities, and monitoring a discharge voltage change of the vehicle battery during the pulse discharge process; For one current intensity, determining a voltage drop rate corresponding to the current intensity according to a discharge voltage change corresponding to the current intensity; The maximum pulse discharge current of the vehicle battery is determined by using voltage drop rates corresponding to a plurality of current intensities, and the maximum pulse discharge capability of the vehicle battery is evaluated based on the maximum pulse discharge current.

2. The vehicle battery evaluation method according to claim 1, characterized in that: Determining the maximum pulse discharge current of the vehicle battery includes: A linear fitting operation is performed on data points indicating voltage drop rates corresponding to a plurality of current intensities, and a maximum pulse discharge current of the vehicle battery is determined based on a result of the linear fitting operation.

3. The vehicle battery evaluation method according to claim 1, characterized in that: Further including: Determining a plurality of battery test conditions for evaluating the vehicle battery; wherein the battery test conditions include: one or more of an external test environment and a remaining battery charge; For each of the battery test conditions, the steps of controlling the vehicle battery to perform pulse discharge at multiple current intensities and monitoring the discharge voltage change of the vehicle battery during the pulse discharge process are performed respectively.

4. The vehicle battery evaluation method according to claim 1, characterized in that: The determining of the voltage drop rate corresponding to the current intensity includes: constructing a voltage-pulse time relationship curve for the vehicle battery based on the monitored discharge voltage change; Calculating a voltage drop rate corresponding to the current intensity according to a voltage change trend indicated by the voltage-pulse time relationship curve; The calculating of the voltage drop rate corresponding to the current intensity includes: intercepting a segmented curve within a set pulse time range from the voltage-pulse time relationship curve; Utilizing the downward trend of the voltage indicated by the segmented voltage curve, the slope corresponding to the segmented curve is calculated; The slope indicates the voltage drop rate corresponding to the current intensity.

5. The vehicle battery evaluation method according to claim 2, characterized in that: The performing of a linear fitting operation on data points indicating voltage drop rates corresponding to a plurality of current intensities includes: Placing data points indicating voltage drop rates corresponding to various current intensities in a preset coordinate system indicating the relationship between voltage change rate and pulse discharge current; Iterative linear fitting is performed on the data points according to the order of the data points indicating the voltage drop rates corresponding to the various current intensities from low to high in the coordinate system.

6. The vehicle battery evaluation method according to claim 5, characterized in that: The iterative linear fitting of the data points comprises: For the first iteration cycle, starting from the data point indicated by the minimum voltage drop rate, at least two data points are selected in order from low to high, and a linear fit is performed on the selected data points; For each iteration cycle except the first iteration cycle, select the data points selected in the previous cycle, and select one or more data points in order from low to high, and perform linear fitting on the selected data points; After all data points have been selected, the iteration stops.

7. The vehicle battery evaluation method according to claim 5, characterized in that: The linear fitting of the selected data points further comprises: According to the data points selected in each iteration cycle, the fitting determination coefficient corresponding to each iteration cycle is calculated; The determining the maximum pulse discharge current of the vehicle battery according to the result of the linear fitting operation includes: When the fitting determination coefficient corresponding to any iterative cycle exceeds the set fitting coefficient threshold, and the fitting determination coefficient corresponding to the subsequent adjacent iterative cycle of the iterative cycle does not exceed the set fitting coefficient threshold, the current corresponding to the maximum data point in the iterative cycle is taken as the maximum pulse discharge current.

8. A vehicle battery evaluation device, characterized in that: include: a discharge operation module, which is used to control the vehicle battery to perform pulse discharge at various current intensities and monitor the discharge voltage change of the vehicle battery during the pulse discharge process; a voltage tracking module configured to determine, for a current intensity, a voltage drop rate corresponding to the current intensity based on a discharge voltage change corresponding to the current intensity; A current evaluation module is configured to determine a maximum pulse discharge current of the vehicle battery by using voltage drop rates corresponding to a plurality of current intensities, and to evaluate a maximum pulse discharge capability of the vehicle battery based on the maximum pulse discharge current.

9. An electronic device for evaluating vehicle batteries, characterized in that: include: one or more processors; a storage device for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program for implementing vehicle battery evaluation, characterized in that: include: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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