Quality guarantee life verification method of battery system

Abstract

The invention provides a quality guarantee life verification method of a battery system. The quality guarantee life verification method of the battery system comprises the steps of S10, performing quality guarantee life simulation on the battery system, and enabling a simulation value of the battery system to meet a design index; step S20, establishing a logical relationship between quality guarantee life simulation and cycle life test, and performing cycle life test on the battery system to obtain an SOHS value and an SOHR value; and S30, judging whether the SOHR value is greater than or equal to the SOHS value, if so, judging that the battery system meets the quality guarantee life requirement, and if not, executing the step of optimizing the battery system, and continuing to execute the step S10. According to the technical scheme of the invention, the problem that the verification result is inaccurate when the battery system is subjected to quality guarantee life verification by using a cycle life test in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular, to a method for verifying the warranty life of a battery system. Background Art

[0002] In actual road conditions, for an electric vehicle equipped with a lithium-ion battery system, the warranty life usually requires that when the service life reaches more than 8 years or the driving mileage under working conditions exceeds 200,000 kilometers, the state of health (SOH) of the battery is not less than 80%. Therefore, vehicle manufacturers or battery suppliers need to evaluate whether the warranty life of the battery system meets the requirements during the development stage of electric vehicles. Generally, in China, simulation means including "cell thermal model, electrical model, aging model, pressure model, vehicle working condition model, and environmental temperature model" are mostly used to predict the warranty life of lithium-ion battery systems. However, how to verify whether the above simulation results are reliable in the shortest time is still a difficult point in the current industry.

[0003] Currently, both vehicle manufacturers and battery suppliers refer to the "Requirements and Test Methods for the Cycle Life of Power Batteries for Electric Vehicles" to conduct cycle life tests on lithium-ion battery systems, and infer whether the battery system meets the warranty life design requirements based on the test results. Usually, after 500 charge-discharge cycles of the battery system, on the basis that the SOH is not less than 90%, it is determined that the battery system can meet the warranty life design requirements. However, since there is no direct logical correlation between the cycle life test of the battery system and the warranty life simulation, there is a problem of inaccurate verification results when using the cycle life test to verify the warranty life of the battery system. Summary of the Invention

[0004] The main object of the present invention is to provide a method for verifying the warranty life of a battery system to solve the problem of inaccurate verification results in the prior art when using the cycle life test to verify the warranty life of the battery system.

[0005] To achieve the above object, the present invention provides a method for verifying the warranty life of a battery system. The method for verifying the warranty life of a battery system includes: Step S10: Perform a warranty life simulation on the battery system and make the simulation value of the battery system meet the design index; Step S20: Establish a logical relationship between the warranty life simulation and the cycle life test, and perform a cycle life test on the battery system to obtain the SOH S value and the SOH R value; Step S30: Judge whether the SOH R value is greater than or equal to the SOH S value. If so, judge that the battery system meets the warranty life requirement. If not, execute the step of optimizing the battery system and continue to execute Step S10.

[0006] In the above technical solution, by establishing the logical relationship between the warranty life simulation and the cycle life test, the SOH is obtained S value and the SOH R value, and the magnitudes of the two are judged. According to whether the SOH R value is greater than or equal to the SOH S value, it is judged whether the warranty life of the battery system meets the requirements. Compared with the prior art in which there is no logical correlation between the warranty life simulation and the cycle life test of the battery system, in the present invention, the logical connection between the warranty life simulation and the cycle life test is established, the difference between the two is eliminated, and the warranty life of the battery system can be more reliably evaluated through the cycle life test. In this way, on the one hand, the uncertainty in the verification process of the battery system can be reduced, thereby improving the verification accuracy of the battery system; on the other hand, not only the test time is saved, but also the test efficiency is improved.

[0007] Further, step S20 includes: step S21: performing a cyclic warranty life simulation on the battery system to obtain the cumulative discharge capacity C1 value; step S22: performing a cycle life simulation on the battery system to obtain the cumulative discharge capacity C2 value; step S23: judging whether the cumulative discharge capacity C2 is equal to the cumulative discharge capacity C1. If so, perform step S24 of obtaining the SOH S value and the SOH R value, and then perform step S30. If not, continue to perform step S22.

[0008] In the above technical solution, by making the cumulative discharge capacity C2 equal to the cumulative discharge capacity C1 (based on the principle of equal cumulative discharge capacity), the logical connection between the cyclic warranty life simulation and the cycle life simulation is realized. In this way, the logical relationship between the warranty life simulation and the cycle life test can be further established to facilitate obtaining the SOH R value and the SOH S value, and judging whether the SOHR value is greater than or equal to the SOHS value, so as to judge whether the warranty life of the battery system meets the requirements through the cycle life test, thereby improving the verification reliability of the warranty life of the battery system.

[0009] Further, step S24 includes: step S25: obtaining the simulated cycle number value X1 of the battery system during the cycle life simulation; step S26: obtaining the SOH corresponding to the simulated cycle number value X1 S value; step S27: obtaining the measured cycle number value X of the battery system during the cycle life test in real time; step S28: judging whether the measured cycle number value X is equal to the simulated cycle number value X1. If so, perform the step of obtaining the SOH R ; if not, perform step S27.

[0010] In the above technical solution, by obtaining the simulated value X1 of the number of cycles and the measured value X of the number of cycles, and making the simulated value X1 of the number of cycles equal to the measured value X of the number of cycles, in this way, the correlation between the cycle life simulation and the cycle life test can be established, so that the SOH can be further used R and SOH S to determine whether the warranty life of the battery system meets the requirements. Furthermore, the cycle life test can be used to determine whether the warranty life of the battery system meets the requirements, so as to improve the verification reliability of the warranty life of the battery system.

[0011] Furthermore, step S21 includes: step S211: specifying the environmental temperature parameter of the battery system, inputting the environmental temperature model, and obtaining the cell cycle aging data; step S212: inputting the cell cycle aging data into the aging model; step S213: performing cycle charge and discharge simulation on the battery system to obtain the cumulative discharge capacity C1.

[0012] In the above technical solution, by accurately obtaining the cumulative discharge capacity C1 during the cycle warranty life simulation stage, a clear test target is set for the subsequent cycle life simulation, so as to facilitate the comparison of the cumulative discharge capacity C2 with C1, thereby providing data support for the evaluation of the warranty life of the battery system.

[0013] Furthermore, step S211 includes step S2111: selecting a temperature value; step S2112: selecting a charge and discharge rate; step S2113: performing cycle charge and discharge on the battery system; step S2114: determining whether the SOH of the battery system is less than the first preset value. If so, execute the step of obtaining the number of cell cycle aging times. If not, continue to execute step S2113; step S2115: repeat steps S2111 to S2114 to obtain multiple numbers of cell cycle aging times to form the cell cycle aging data.

[0014] In the above technical solution, the operating conditions of the battery system during the simulation are further limited. The number of cell cycle aging times is obtained through the temperature value and the charge and discharge rate. The cell cycle aging data composed of multiple numbers of cell cycle aging times is used to obtain the value of the cumulative discharge capacity C1, so that the value of the cumulative discharge capacity C2 can be obtained based on the principle of equal cumulative discharge capacity, and then the simulated value X1 of the number of cycles can be further obtained, so as to facilitate the evaluation of the warranty life of the battery system.

[0015] Furthermore, step S22 includes: step S221: specifying the environmental temperature parameter of the battery system as 25°C and inputting the environmental temperature model; step S222: selecting a specified charge and discharge test step and inputting it into the vehicle operating condition model; step S223: performing cycle charge and discharge simulation on the battery system; step S224: obtaining the cumulative discharge capacity C2.

[0016] In the above technical solution, by obtaining the cumulative discharge capacity C2 and establishing the relationship between the cumulative discharge capacity C2 and the cumulative discharge capacity C1, thus, according to the principle of equivalent cumulative discharge capacity, the simulation value X1 of the number of cycles can be obtained, and based on the simulation value X1 of the number of cycles, the correlation between the cycle life simulation and the cycle life test can be established, so that the reliability of the warranty life of the battery system can be verified according to the cycle life test.

[0017] Further, after step S223 and before step S224, step S22 further includes a step of standing still the battery system.

[0018] In the above technical solution, the standing still process can reduce the temperature of the battery and reduce the measurement error caused by the thermal effect. In this way, the measurement accuracy of the cumulative discharge capacity C2 can be improved.

[0019] Further, step S10 includes: step S11: performing a warranty life simulation on the battery system to obtain a simulation value of capacity fade; step S12: determining whether the simulation value of capacity fade meets the design index. If so, outputting the simulation value of capacity fade. If not, performing the step of optimizing the battery system and then performing step S11.

[0020] In the above technical solution, it is determined whether the battery system meets the design index according to the simulation value of capacity fade. Only when the battery system meets the design requirements can the warranty life of the battery system be evaluated. If the battery system does not meet the design index, then the battery system is optimized and then judged again.

[0021] Further, step S11 includes: performing a warranty life simulation on the battery system by means of simulation of a cell thermal model, an electrical model, an aging model, a pressure model, a vehicle operating condition model, and an ambient temperature model.

[0022] In the above technical solution, by combining a cell thermal model, an electrical model, an aging model, a pressure model, a vehicle operating condition model, and an ambient temperature model, various factors affecting the battery life can be comprehensively considered, so as to perform a more accurate and comprehensive simulation evaluation of the warranty life of the battery system.

[0023] Further, specifying the charge and discharge test steps includes inputting the provisions of the "GB / T 31484-2015" standard in the vehicle operating condition model, or inputting the charge and discharge test steps specified by the vehicle manufacturer and the battery supplier in the vehicle operating condition model.

[0024] In the above technical solution, by inputting the charging and discharging test steps specified by the standard or designated in the vehicle operating condition model, the present invention can more scientifically simulate the charging and discharging behavior of the battery system in the actual use scenario. In this way, not only the accuracy and reliability of the verification result of the warranty life are improved, but also the verification process is closer to the actual use situation.

[0025] Applying the technical solution of the present invention, by establishing the logical relationship between the warranty life simulation and the cycle life test, the SOH S value and the SOH R value are obtained and the magnitudes of the two are judged. According to whether the SOH R value is greater than or equal to the SOH S value to judge whether the warranty life of the battery system meets the requirements. Compared with the prior art in which there is no logical correlation between the warranty life simulation and the cycle life test of the battery system, in the present invention, the logical correlation between the warranty life simulation and the cycle life test is established, and the difference between the two is eliminated. It is possible to more reliably evaluate whether the warranty life of the battery system is accurate through the cycle life test. In this way, on the one hand, the uncertainty in the verification process of the battery system can be reduced, thereby improving the verification accuracy of the battery system; on the other hand, not only the test time is saved, but also the test efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 The schematic diagram of the simulation result of the embodiment of the method for verifying the warranty life of the battery system of the present invention is shown;

[0028] Figure 2 The schematic flow diagram of the method for verifying the warranty life of the battery system of the present invention is shown;

[0029] Figure 3 The schematic flow diagram of step S20 of the method for verifying the warranty life of the battery system of the present invention is shown;

[0030] Figure 4 The schematic flow diagram of step S24 of the method for verifying the warranty life of the battery system of the present invention is shown;

[0031] Figure 5 The schematic flow diagram of step S21 of the method for verifying the warranty life of the battery system of the present invention is shown;

[0032] Figure 6 The schematic flow diagram of step S211 of the method for verifying the warranty life of the battery system of the present invention is shown;

[0033] Figure 7 Shows the schematic flow chart of step S22 of the method for verifying the warranty life of the battery system of the present invention;

[0034] Figure 8 Shows the schematic flow chart of step S10 of the method for verifying the warranty life of the battery system of the present invention;

[0035] Figure 9 Shows the relationship diagram between the number of cycles and the cumulative discharge capacity C1 of the method for verifying the warranty life of the battery system of the present invention. Detailed implementation manners

[0036] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0037] As Figure 2 shown, the embodiment of the present invention provides a method for verifying the warranty life of a battery system. The method for verifying the warranty life of a battery system includes: Step S10: performing a warranty life simulation on the battery system and making the simulation value of the battery system meet the design index; Step S20: establishing a logical relationship between the warranty life simulation and the cycle life test, and performing a cycle life test on the battery system to obtain the SOH S value and the SOH R value; Step S30: judging whether the SOH R value is greater than or equal to the SOH S value. If so, it is judged that the battery system meets the warranty life requirement. If not, the step of optimizing the battery system is executed, and Step S10 is continued to be executed.

[0038] In the above technical solution, by establishing a logical relationship between the warranty life simulation and the cycle life test, obtaining the SOH S value and the SOH R value and judging the magnitudes of the two, according to whether the SOH R value is greater than or equal to the SOH S value to judge whether the warranty life of the battery system meets the requirement. Compared with the prior art where there is no logical correlation between the warranty life simulation and the cycle life test of the battery system, in the present invention, a logical connection is established between the warranty life simulation and the cycle life test, and the difference between the two is eliminated. It is possible to more reliably evaluate whether the warranty life of the battery system is accurate through the cycle life test. In this way, on the one hand, the uncertainty in the verification process of the battery system can be reduced, thereby improving the verification accuracy of the battery system; on the other hand, not only the test time is saved, but also the test efficiency is improved.

[0039] Specifically, in the embodiments of the present invention, by comparing the SOH R value with the SOH S value, the present invention provides a clear judgment criterion, which can clearly judge whether the battery system meets the requirements of the warranty life, and enhances the objectivity and accuracy of the verification result.

[0040] Specifically, in the embodiments of the present invention, the battery system is a vehicle-mounted lithium-ion battery system.

[0041] It should be noted that in the embodiments of the present invention, there is no sequence order between step S10 and step S20. Step S10 and step S20 can be in a parallel relationship, or step S10 can be before step S20, or step S20 can be before step S10.

[0042] Specifically, in the embodiments of the present invention, optimizing the battery system means adjusting the design parameters of the lithium-ion battery. For example, improving the energy density of the lithium-ion battery.

[0043] As Figure 3 shown, in the embodiments of the present invention, step S20 includes: step S21: performing a cyclic warranty life simulation on the battery system to obtain the discharge cumulative capacity C1 value; step S22: performing a cyclic life simulation on the battery system to obtain the discharge cumulative capacity C2 value; step S23: judging whether the discharge cumulative capacity C2 is equal to the discharge cumulative capacity C1. If so, execute step S24 of obtaining the SOH S value and the SOH R value, and then execute step S30. If not, continue to execute step S22.

[0044] In the above technical solution, by making the discharge cumulative capacity C2 equal to the discharge cumulative capacity C1 (based on the principle of equal discharge cumulative capacity), the logical association between the cyclic warranty life simulation and the cyclic life simulation is realized. In this way, the logical relationship between the warranty life simulation and the cyclic life test can be further established, so as to obtain the SOH R value and the SOH S value, and judge whether the SOH R value is greater than or equal to the SOH S value, so as to judge whether the warranty life of the battery system meets the requirements through the cyclic life test, and further improve the verification reliability of the warranty life of the battery system.

[0045] As Figure 4 shown, in the embodiments of the present invention, step S24 includes: step S25: obtaining the cyclic number simulation value X1 of the battery system during the cyclic life simulation; step S26: obtaining the SOH SValue; Step S27: Obtain the actual measured value X of the number of cycles during the cycle life test of the battery system in real time; Step S28: Determine whether the actual measured value X of the number of cycles is equal to the simulated value X1 of the number of cycles. If so, execute the step of obtaining the SOH R ; If not, execute Step S27.

[0046] In the above technical solution, by obtaining the simulated value X1 of the number of cycles and the actual measured value X of the number of cycles, and making the simulated value X1 of the number of cycles equal to the actual measured value X of the number of cycles, in this way, a correlation can be established between the cycle life simulation and the cycle life test, so that the SOH R and SOH S can be further used to determine whether the warranty life of the battery system meets the requirements. Furthermore, the cycle life test can be used to determine whether the warranty life of the battery system meets the requirements, so as to improve the verification reliability of the warranty life of the battery system.

[0047] Specifically, in the embodiment of the present invention, the simulated value X1 of the number of cycles corresponds to the SOH S value, that is, when the cumulative discharge capacity C2 is equal to the cumulative discharge capacity C1, the simulated value X1 of the number of cycles and the SOH S value of the battery system are obtained.

[0048] As Figure 5 shown, in the embodiment of the present invention, Step S21 includes: Step S211: Specify the environmental temperature parameter of the battery system, input the environmental temperature model, and obtain the cell cycle aging data; Step S212: Input the cell cycle aging data into the aging model; Step S213: Perform cycle charge and discharge simulation on the battery system to obtain the cumulative discharge capacity C1.

[0049] In the above technical solution, by accurately obtaining the cumulative discharge capacity C1 during the cycle warranty life simulation stage, a clear test target is set for the subsequent cycle life simulation, so as to facilitate the comparison of the cumulative discharge capacity C2 with C1, thereby providing data support for the warranty life assessment of the battery system.

[0050] Specifically, in the embodiment of the present invention, specifying the environmental temperature parameter of the battery system means specifying the temperature of the battery system, that is, by means of artificially setting the temperature, the battery temperature is set to the seasonal temperature in Sanya area.

[0051] Specifically, in the embodiment of the present invention, the cumulative discharge capacity C1 is the total amount of electricity released by the battery system during multiple discharges, and the cumulative discharge capacity C1 is obtained by technicians through calculation (that is, the cumulative discharge capacity C1 is obtained by integrating the discharge current of the battery system over time using the ampere-hour integration method).

[0052] As Figure 6As shown, in the embodiment of the present invention, step S211 includes step S2111: selecting a temperature value; step S2112: selecting a charge-discharge rate; step S2113: performing cyclic charge and discharge on the battery system; step S2114: determining whether the SOH of the battery system is less than a first preset value. If so, execute the step of obtaining the number of cycle aging of the battery cells. If not, continue to execute step S2113; step S2115: repeat steps S2111 to S2114 to obtain multiple numbers of cycle aging of the battery cells to form cycle aging data of the battery cells.

[0053] In the above technical solution, the operating conditions of the battery system during the simulation process are further defined. The number of cycle aging of the battery cells is obtained through the temperature value and the charge-discharge rate. The cycle aging data of the battery cells composed of multiple numbers of cycle aging of the battery cells is used to obtain the value of the cumulative discharge capacity C1, so that the value of the cumulative discharge capacity C2 can be obtained based on the principle of equivalent cumulative discharge capacity, and then the simulation value X1 of the number of cycles is further obtained to facilitate the evaluation of the warranty life of the battery system.

[0054] Specifically, in the embodiment of the present invention, the cycle aging data of the battery cells is data composed of multiple numbers of cycle aging of the battery cells, and the number of cycle aging of the battery cells is obtained through steps S3111 to S3114.

[0055] Preferably, in the embodiment of the present invention, the first preset value is 70%.

[0056] Specifically, in the embodiment of the present invention, the number of cycle aging of the battery cells refers to the number of cycles of performing cyclic charge and discharge on the battery system when the SOH of the battery system is less than the first preset value.

[0057] Preferably, in the embodiment of the present invention, the temperature and the charge rate are set manually by technicians, and among them, the selected temperature value needs to be above 25°C.

[0058] As Figure 7 shown, in the embodiment of the present invention, step S22 includes: step S221: designating the ambient temperature parameter of the battery system as 25°C and inputting the ambient temperature model; step S222: selecting a designated charge-discharge test step and inputting it into the vehicle operating condition model; step S223: performing cyclic charge and discharge simulation on the battery system; step S224: obtaining the cumulative discharge capacity C2.

[0059] In the above technical solution, by obtaining the cumulative discharge capacity C2 and establishing the relationship between the cumulative discharge capacity C2 and the cumulative discharge capacity C1, in this way, according to the principle of equivalent cumulative discharge capacity, the simulated value X1 of the number of cycles can be obtained, and the correlation between the simulated cycle life and the cycle life test can be established based on the simulated value X1 of the number of cycles, so that the reliability of the warranty life of the battery system can be verified according to the cycle life test.

[0060] Specifically, in the embodiments of the present invention, since the battery system has the characteristics of constant test environment temperature and fast charge and discharge frequency during the cycle life test; in order to eliminate the environmental temperature difference between the warranty life condition and the cycle life condition and the calendar aging difference caused by the charge and discharge frequency, the present invention adjusts the temperature input value during the warranty life simulation process, and performs cyclic charge and discharge on the battery system without inputting the calendar aging data of the battery cells, and solves this difference problem by adopting a more stringent environmental temperature model and aging model.

[0061] It should be noted that in the embodiments of the present invention, the cumulative discharge capacity C2 is the total amount of electricity released by the battery system during multiple discharges, and the cumulative discharge capacity C2 is calculated by those skilled in the art (that is, the cumulative discharge capacity C2 is obtained by integrating the change of the discharge current of the battery system with time in the form of ampere-hour integration).

[0062] As Figure 7 shown, in the embodiments of the present invention, after step S223 and before step S224, step S22 further includes a step of statically placing the battery system.

[0063] In the above technical solution, the static process can reduce the temperature of the battery and reduce the measurement error caused by the thermal effect. In this way, the measurement accuracy of the cumulative discharge capacity C2 can be improved.

[0064] Preferably, in the embodiments of the present invention, after the battery system finishes charging and discharging, the battery system needs to be statically placed for 1 hour.

[0065] As Figure 8 shown, in the embodiments of the present invention, step S10 includes: step S10 includes: step S11: performing a warranty life simulation on the battery system to obtain a simulated value of capacity fade; step S12: determining whether the simulated value of capacity fade meets the design index. If so, output the simulated value of capacity fade. If not, perform the step of optimizing the battery system and perform step S11.

[0066] In the above technical solution, it is determined whether the battery system meets the design index according to the simulated value of capacity fade. Only when the battery system meets the design requirements can the warranty life of the battery system be evaluated. If the battery system does not meet the design index, then the battery system is optimized and then judged again.

[0067] Specifically, in the embodiments of the present invention, if the simulation value does not meet the design index, steps S11 and S12 are continuously executed until the simulation value meets the design index. This closed-loop process ensures that the design of the battery system can be continuously iterated and optimized until its performance meets the design index. Through this process, the designer can take corresponding measures for improvement, thereby improving the overall performance and reliability of the battery system.

[0068] Specifically, in the embodiments of the present invention, the simulation value of capacity fade is SOH, where SOH is the ratio of the current capacity to the initial capacity of a lithium-ion battery. The design index in step S10 refers to that the SOH of the lithium-ion battery after the warranty life simulation is greater than or equal to a second preset value of the SOH (state of health) of the lithium-ion battery. The above-mentioned second preset value is set artificially by technicians (specified by vehicle manufacturers).

[0069] As Figure 8 shown, in the embodiments of the present invention, step S11 includes: performing a warranty life simulation on the battery system by means of simulation of a cell thermal model, an electrical model, an aging model, a pressure model, a vehicle operating condition model, and an ambient temperature model.

[0070] In the above technical solution, by combining a cell thermal model, an electrical model, an aging model, a pressure model, a vehicle operating condition model, and an ambient temperature model, various factors affecting the battery life can be comprehensively considered, so as to perform a more accurate and comprehensive simulation evaluation on the warranty life of the battery system.

[0071] Specifically, in the embodiments of the present invention, step S11 can adopt the existing technology, which will not be elaborated here.

[0072] It should be noted that in the embodiments of the present invention, the cell thermal model is used to simulate the influence of the thermal behavior of the battery system at different temperatures on its life, the electrical model is used to simulate the influence of the electrical behavior of the battery system under different conditions on its life, the aging model is used to simulate the influence of the performance degradation of the battery system during long-term use on its life, the pressure model is used to simulate the influence of different mechanical stresses when multiple cells are stacked on the life of the battery system, the vehicle operating condition model is used to simulate the load and environmental changes of the battery system under real operating conditions, and the ambient temperature model is used to simulate the influence of the battery system at different temperatures on its life.

[0073] As Figure 7 shown, in the embodiments of the present invention, specifying the charge and discharge test steps includes inputting the provisions of the "GB / T 31484-2015" standard in the vehicle operating condition model, or inputting the charge and discharge test steps specified by the vehicle manufacturer and the battery supplier in the vehicle operating condition model.

[0074] In the above technical solution, by inputting the charge and discharge test steps specified by the standard or designated in the vehicle operating condition model, the present invention can more scientifically simulate the charge and discharge behavior of the battery system in the actual use scenario. In this way, not only the accuracy and reliability of the warranty life verification result are improved, but also the verification process is closer to the actual use situation.

[0075] Specifically, in the embodiments of the present invention, inputting the provisions of the "GB / T 31484-2015" standard in the vehicle operating condition model means adopting either the standard cycle life or the working condition cycle life, and the user can select according to actual needs. The standard cycle life refers to the number of charge and discharge cycles experienced when the SOH of the battery system decays to a preset value under standard test conditions; the working condition cycle life refers to the number of charge and discharge cycles experienced when the SOH of the battery system decays to a preset value under actual use conditions.

[0076] Specifically, in the embodiments of the present invention, when the provisions of the "GB / T 31484-2015" standard cannot meet the user's needs, the user can choose to input the charge and discharge test steps designated by the vehicle enterprise and the battery supplier, and the above charge and discharge test steps are artificially set by the vehicle enterprise and the battery supplier.

[0077] Specifically, in the embodiments of the present invention, the battery system is assembled from 160Ah battery cells in a combination form of 1 parallel and 134 series. The following is an embodiment of the warranty life verification method for the battery system. This life verification method includes the following steps:

[0078] Step 1: Use simulation means including "battery cell thermal model, electrical model, aging model, pressure model, vehicle operating condition model, ambient temperature model" to conduct warranty life simulation on the battery system. Through simulation, it is obtained that the SOH of the battery system operating at a specified working condition in Sanya area for 8 years and 150,000 kilometers is 82%, meeting the design index requirements;

[0079] Step 2: Adjust the parameters of the temperature module and the vehicle operating condition module of the warranty life simulation to facilitate the simulation of the cycle life test of the battery system, that is, specify the parameters of the ambient temperature model and the aging model mentioned in Step 1. Specifically: select the four-season temperatures in Sanya area as the input value of the ambient temperature model; in the aging model, only select the battery cell cycle aging data as the input value in the aging model, and do not select the calendar aging data of the battery cell;

[0080] Step 3: Record the cumulative discharge capacity C1 = 62631Ah, the cumulative discharge power E1 = 27827kWh, and the SOH1 = 94.49% of the battery system during the simulation process;

[0081] Step 4: Conduct cycle life simulation on the battery system. The cycle life simulation is evolved by regulating the environmental temperature model and vehicle operating condition model of the warranty life simulation. Among them, 25°C is selected as the input value of the environmental temperature model, and the battery system is charged and discharged in a step cycle of 1C charging and 1C discharging. The charging and discharging test steps specified in the "GB / T 31484-2015" standard or specified by the vehicle enterprise and battery supplier are input into the vehicle operating condition model; after charging and discharging, the battery system needs to be static for 1 hour to make the highest temperature inside the battery system reach the temperature adapted to the environment;

[0082] Step 5: Control the cumulative discharge capacity C2 of the battery system during the cycle simulation to be equal to the cumulative discharge capacity C1 in Step 3, that is, when C2 = C1, SOH S = 92.8%, and the simulation value X1 of the cycle times of the battery system = 408 times; The cycle number of the battery system based on the equal cumulative discharge capacity is shown in Figure 9 ;

[0083] Step 6: Conduct an actual cycle life test on the battery system. The steps of the cycle life test (i.e., charging and discharging the battery system) are the same as those in Step 4; After the cycle times of the battery system reach 408 cycles, that is, X = X1, the actual measured SOH R = 93.4% > SOH S = 92.8% (see the summary results in Figure 1 ), which proves that the battery system can meet the warranty life requirements.

[0084] Specifically, in the embodiment of the present invention, the present invention provides a method for verifying the warranty life of a battery system, as Figures 2 to 8 shown. This method includes: constructing a logical association between the warranty life simulation and the cycle life simulation, and then verifying the reliability of the warranty life result through the cycle life test result. Specifically: (1) Using simulation technologies including "cell thermal model, electrical model, aging model, pressure model, vehicle operating condition model, environmental temperature model" to predict the warranty life simulation result of the battery system, and this simulation result needs to meet the design index requirements; (2) Regulating the parameters of the environmental temperature model and aging model of the warranty life simulation to obtain the cumulative discharge capacity C1 of the warranty life simulation after adjusting the working conditions; (3) Conducting cycle life simulation on the battery system, controlling the cumulative discharge capacity value C2 of the cycle life simulation to be the same as C1, and obtaining the charge and discharge times X1 and capacity retention rate (the ratio of the actual available power to the initial capacity of the battery system after cyclic charge and discharge) SOH S ; (4) Conducting cycle life test on the battery system. When the charge and discharge times X are the same as X1, if the capacity retention rate SOH R is greater than or equal to SOH S, it is determined that the battery system meets the quality assurance life requirements, and the quality assurance life simulation results are reliable. The present invention proposes a verification method for verifying the quality assurance life of a battery system based on the cycle life results, which can be applied to the life verification of all power batteries for new energy vehicles. The life verification method has strong versatility and accurate and reliable results.

[0085] Specifically, in the embodiments of the present invention, first, since the battery system has the characteristics of constant test environment temperature and fast charge and discharge frequency during the cycle life test, in order to eliminate the environmental temperature difference between the quality assurance life and the cycle life and the calendar aging difference caused by the charge and discharge frequency, the present invention adjusts the temperature input value during the quality assurance life simulation and performs cyclic charge and discharge on the battery system without inputting the calendar aging data of the battery cells, and solves this difference problem by adopting a more stringent environmental temperature model and aging model; second, on the basis of eliminating the working condition differences between the two, the present invention proposes a principle based on the equivalence of the cumulative discharge capacity (C1 equals C2), realizing the logical connection between the quality assurance life simulation and the cycle life simulation; further, as long as the charge and discharge test steps or standards specified by the vehicle enterprise and the battery supplier (such as national standards or international standards) are used to perform the cycle life test on the battery system to be tested, and the cycle life test results are compared with the cycle life simulation values, it can be verified whether the quality assurance life of the battery system to be tested meets the design requirements, while also saving the test time and improving the test efficiency; third, the quality assurance life verification method of the battery system of the present invention can be applied to the life verification of all power batteries for new energy vehicles, and has strong versatility.

[0086] Specifically, as Figure 9 shown, in the embodiments of the present invention, a cyclic quality assurance life simulation is performed on the battery system (the operating time of the battery system is 8 years), and the cumulative discharge capacity C1 is obtained as 62631 Ah. Based on the principle of equivalence of the cumulative discharge capacity, the cumulative discharge capacity C2 is made equal to 62631 Ah. When the cumulative discharge capacity C2 is equal to 62631 Ah, the simulated cycle number X1 is obtained as 408 times.

[0087] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: by establishing a logical relationship between the quality assurance life simulation and the cycle life test, obtaining the SOH S value and the SOH R value and judging the size of the two, and according to whether the SOH R value is greater than or equal to the SOH SUse the value to determine whether the warranty life of the battery system meets the requirements. Compared with the lack of logical relevance between the warranty life simulation and the cycle life test of the battery system in the prior art, in the present invention, a logical connection is established between the warranty life simulation and the cycle life test, and the difference between the two is eliminated. It is possible to more reliably evaluate whether the warranty life of the battery system is accurate through the cycle life test. In this way, on the one hand, the uncertainty during the verification process of the battery system can be reduced, thereby improving the verification accuracy of the battery system; on the other hand, not only the test time is saved, but also the test efficiency is improved.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for verifying the warranty life of a battery system, characterized in that, Including: Step S10: Conduct a warranty life simulation on the battery system, and make the simulation value of the battery system meet the design specifications; Step S20: Establish the logical relationship between the warranty life simulation and the cycle life test, and perform the cycle life test on the battery system to obtain the SOH S value and SOH R value; Step S30: Determine the SOH R value is greater than or equal to the SOH S value. If so, determine that the battery system meets the warranty life requirement. If not, perform the steps to optimize the battery system and continue to execute step S10.

2. The method for verifying the warranty life of the battery system according to claim 1, wherein The step S20 includes: Step S21: Conduct a cyclic warranty life simulation on the battery system to obtain the discharged cumulative capacity C1 value; Step S22: Conduct a cyclic life simulation on the battery system to obtain the discharged cumulative capacity C2 value; Step S23: Determine whether the cumulative discharge capacity C2 is equal to the cumulative discharge capacity C1. If so, execute step S24 to obtain the SOH S value and SOH R value, and then execute step S30. If not, continue to execute step S22.

3. The method for verifying the warranty life of the battery system according to claim 2, wherein The step S24 includes: Step S25: Obtain the cyclic number simulation value X1 of the battery system during the cyclic life simulation; Step S26: Obtain the SOH value corresponding to the simulation value X1 of the number of cycles S value; Step S27: Real-time obtain the measured cyclic number X of the battery system during the cyclic life test; Step S28: Determine whether the measured value X of the number of cycles is equal to the simulated value X1 of the number of cycles. If so, execute the step of obtaining the SOH R ; if not, execute step S27.

4. The method for verifying the warranty life of the battery system according to claim 2, wherein The step S21 includes: Step S211: Specify the environmental temperature parameter of the battery system, input it into the environmental temperature model, and obtain the cell cyclic aging data; Step S212: Input the cell cyclic aging data into the aging model; Step S213: Conduct a cyclic charge and discharge simulation on the battery system to obtain the discharged cumulative capacity C1.

5. The method for verifying the warranty life of the battery system according to claim 4, wherein The step S211 includes Step S2111: Select a temperature value; Step S2112: Select a charge and discharge rate; Step S2113: Conduct a cyclic charge and discharge on the battery system; Step S2114: Determine whether the SOH of the battery system is less than the first preset value. If so, execute the step of obtaining the cell cyclic aging times. If not, continue to execute the step S2113; Step S2115: Repeat the steps S2111 to S2114 to obtain multiple cell cyclic aging times to form the cell cyclic aging data.

6. The method for verifying the warranty life of the battery system according to claim 2, wherein The step S22 includes: Step S221: Specify the environmental temperature parameter of the battery system as 25°C and input it into the environmental temperature model; Step S222: Select a specified charge and discharge test step and input it into the vehicle operating condition model; Step S223: Conduct a cyclic charge and discharge simulation on the battery system; Step S224: Obtain the discharged cumulative capacity C2.

7. The method for verifying the warranty life of the battery system according to claim 6, characterized in that After the step S223 and before the step S224, the step S22 further includes a step of statically placing the battery system.

8. The method for verifying the warranty life of the battery system according to any one of claims 1 to 7, characterized in that, The step S10 includes: Step S11: Conduct a warranty life simulation on the battery system to obtain a capacity attenuation simulation value; Step S12: Determine whether the capacity attenuation simulation value meets the design specifications. If so, output the capacity attenuation simulation value. If not, execute the step of optimizing the battery system and execute the step S11.

9. The method for verifying the warranty life of the battery system according to claim 8, characterized in that, The step S11 includes: Conduct a warranty life simulation on the battery system by means of simulation of a cell thermal model, an electrical model, an aging model, a pressure model, a vehicle operating condition model, and an environmental temperature model.

10. The method for verifying the warranty life of the battery system according to claim 6, wherein, Specifying the charge and discharge test steps includes inputting the provisions of the "GB / T 31484-2015" standard in the vehicle operating condition model, or inputting the charge and discharge test steps specified by the vehicle manufacturer and the battery supplier in the vehicle operating condition model.

Images