Power determination method and device of power battery, equipment and storage medium

Abstract

The invention provides a power determination method and device for a power battery, equipment and a storage medium, and the method comprises the steps: obtaining first state data of the power battery if a vehicle is in a driving working condition; determining first available power of the power battery according to the first state data and a power mapping table; determining second state data of the power battery according to the first state data, model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery; and performing correction processing on the first available power based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery. The first available power is corrected through the second state data and the preset power correction parameter, and the influence of the second state data of the power battery in the actual use process on the maximum available power is considered, so that the obtained first target available power is close to the actual power capability of the power battery; and the safety and the dynamic property of vehicle driving are ensured.

Description

Technical Field

[0001] The present application relates to the field of power batteries for new energy vehicles, and specifically to a method, device, equipment and storage medium for determining the power of a power battery. Background Art

[0002] With the continuous improvement of power battery technology and the increasing cost advantages, the sales share of new energy vehicles has gradually expanded. The power source has switched from traditional internal combustion engines to batteries and internal combustion engines or batteries alone. The power performance and power usage strategy of power batteries are particularly important in the development of new energy vehicles.

[0003] The power usage strategy of new energy vehicles mainly focuses on the power performance test of battery cell components, the power control strategy of the battery management system (BMS) and the power usage strategy of the whole vehicle. The first two links involve the acquisition of the actual power capacity of the power battery of new energy vehicles and the estimation of the power capacity in all scenarios throughout the life cycle. They play a vital role in the power experience and acceleration safety of new energy vehicles in use, and are the key to the technical optimization and improvement in the current power battery research and development work. In related technologies, the estimation method of power battery power capacity is mostly based on the mapping map of the BMS control strategy obtained offline, estimating the maximum available power of the power battery. However, as the mileage of new energy vehicles increases, in addition to the varying degrees of attenuation of the cruising range, the available power will also attenuate with the increase of the direct current resistance (DCR). Therefore, the method of determining the maximum available power only through the offline map table deviates from the actual power capacity of the power battery. The power capacity estimated in the use of the whole vehicle may be overpowered or too conservative, and the driving safety and power of new energy vehicles cannot be guaranteed. Summary of the invention

[0004] The present application provides a power determination method, device, equipment and storage medium for a power battery. The method can obtain a maximum available power close to the actual power capacity of the power battery, thereby ensuring the safety and power of vehicle driving.

[0005] The technical solution of this application is implemented as follows:

[0006] An embodiment of the present application provides a method for determining the power of a power battery, comprising: if a vehicle is in a driving condition, obtaining first state data of the power battery of the vehicle; determining a first available power of the power battery according to the first state data and a pre-established power mapping table; determining second state data of the power battery according to a correspondence between the first state data, model parameters of an equivalent circuit corresponding to the power battery, and the state data of the power battery; and correcting the first available power based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery.

[0007] According to the above technical means, the actual second state data of the power battery can be determined through the first state data obtained by the vehicle under driving conditions, and the correspondence between the model parameters of the corresponding equivalent circuit of the power battery and the state data of the power battery. Furthermore, the first available power is corrected according to the second state data and the preset power correction parameters, and the influence of the second state data of the power battery on the maximum available power during actual use of the power battery is taken into account, so that the obtained first target available power is close to the actual power capacity of the power battery, thereby ensuring the safety and power of vehicle driving.

[0008] Furthermore, the first available power is corrected based on the second state data and the preset power correction parameter to obtain the first target available power of the power battery, including: determining a reference power correction parameter based on the second state data; determining a target power correction parameter based on the reference power correction parameter and the preset power correction parameter; and correcting the first available power based on the target power correction parameter to obtain the first target available power.

[0009] According to the above technical means, the target power correction parameter is determined according to the reference power parameter determined by the second state data of the power battery and the preset power correction parameter, and the target correction parameter can be determined for the attenuation level of the actual vehicle by combining offline calibration with online estimation. The theoretical maximum available power of the power battery can be corrected in real time based on the target power correction parameter, which can avoid the preset power correction parameter determined offline being too strict and affecting the actual user experience.

[0010] Further, determining the target power correction parameter based on the reference power correction parameter and the preset power correction parameter includes: determining the absolute value of the difference between the preset power correction parameter and the reference power correction parameter; if the absolute value of the difference is less than a preset threshold, determining the average value of the preset power correction parameter and the reference power correction parameter as the target power correction parameter.

[0011] According to the above technical means, if the absolute value of the difference between the preset power correction parameter and the reference power correction parameter is less than the preset threshold value, it means that the preset power correction parameter and the reference power correction parameter are relatively close. By combining the preset power correction parameter determined offline and the reference power correction parameter determined according to the second state data of the battery during actual use of the power battery, the determined target power correction parameter can be made more reasonable, thereby improving the accuracy of the maximum available power of the power battery.

[0012] Furthermore, it also includes: if the absolute value of the difference is greater than the preset threshold, determining the preset power correction parameter as the target maximum available power.

[0013] According to the above technical means, if the absolute value of the difference between the preset power correction parameter and the reference power correction parameter is greater than the preset threshold, it means that the reference power correction parameter determined by the actual second state data of the power battery may be wrong. At this time, using the preset power correction parameter as the target power correction parameter can prevent the target power correction parameter from deviating too much, thereby ensuring safe driving of the vehicle.

[0014] Furthermore, it also includes: when the power battery is in a low charge state, based on the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery, estimating the second available power of the power battery; based on the first target available power and the second available power, determining the second target available power of the power battery.

[0015] According to the above technical means, the second target available power is determined by combining the first target available power after the power battery SOH is corrected and the second available power estimated based on the status data of the power battery in a low charge state. The influence of the status data of the power battery during use on the maximum available power is taken into account, so that the maximum available power that meets the actual working conditions can be obtained.

[0016] Further, determining the second target available power of the power battery based on the first target available power and the second available power includes at least one of the following: if the first target available power is less than the second available power, determining the first target available power as the second target power; if the first target available power is greater than the second available power, determining the second available power as the second target power; if the first target available power is equal to the second available power, determining the first target available power or the second available power as the second target power.

[0017] According to the above technical means, by determining the smaller value of the first target available power and the second available power as the second target available power, it is possible to avoid large deviations and ensure the safety of vehicle driving while ensuring that the determined maximum available power is close to the actual power capacity of the power battery.

[0018] Further, estimating the second available power of the power battery based on the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the status data of the power battery includes: determining third state data of the power battery in a low charge state; determining the second available power according to the third state data and the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the status data of the power battery.

[0019] According to the above technical means, combined with the third state data of the power battery in a low charge state, and the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery, it is possible to estimate the maximum available power of the power battery according to the real-time state of the power battery, and obtain a second available power that is closer to the actual maximum available power.

[0020] Furthermore, it also includes: using the test current method to test the single cell of the power battery to obtain the corresponding relationship between the first attribute parameter and the second attribute parameter of the single cell; determining the third available power of the single cell according to the corresponding relationship between the first attribute parameter and the second attribute parameter; determining the fourth available power of the power battery based on the third available power and the series-parallel coefficient of the power battery; and creating the power mapping table based on the first attribute parameter and the fourth available power.

[0021] According to the above technical means, the single cell is tested by the test current method to obtain the maximum available power of the single cell, and the maximum available power of the whole battery pack is calculated based on the maximum available power of the single cell. The power capacity of the power battery can be quickly obtained on the basis of ensuring accuracy, and the performance of the power battery can be evaluated.

[0022] Further, the power mapping table is created based on the first attribute parameter and the fourth available power, including: based on the first attribute parameter, verifying the power battery using a power test method to obtain a verification result; based on the verification result, correcting the fourth available power to obtain a corrected available power; and creating the power mapping table based on the corrected available power and the first attribute parameter.

[0023] According to the above-mentioned technical means, after the fourth available power of the whole battery pack is obtained by testing the single battery cell based on the test current method, the fourth available power that does not conform to the actual situation can be corrected by actually verifying the whole battery pack, so as to obtain a more accurate maximum available power of the power battery and improve the accuracy of the power mapping table finally established.

[0024] Furthermore, the method of testing the single cell of the power battery by using the test current method to obtain the corresponding relationship between the first attribute parameter and the second attribute parameter of the single cell includes: adjusting the single cell to a specific first attribute parameter, and performing a pulse discharge test on the single cell to obtain a specific second attribute parameter corresponding to the specific first attribute parameter; and fitting the specific first attribute parameter and the specific second attribute parameter to obtain the corresponding relationship between the first attribute parameter and the second attribute parameter of the single cell.

[0025] According to the above technical means, the correspondence between the first attribute parameter and the second attribute parameter of the single cell of the power battery can be obtained, so as to facilitate the subsequent determination of the maximum available power of the single cell according to the correspondence, thereby providing a basic condition for determining the maximum available power of the power battery.

[0026] Furthermore, the model parameters of the power battery corresponding to the equivalent circuit include multiple ones, and the state data of the power battery includes first sub-state data and second sub-state data; the process of creating the correspondence between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery includes: performing a first charge and discharge test on the single cell of the power battery to obtain the correspondence between the i-th model parameter and the first sub-state data; wherein i is greater than 0 and less than or equal to the number of model parameters; performing a second charge and discharge test on the single cell to obtain the correspondence between the i-th model parameter and the second sub-state data; based on the correspondence between the i-th model parameter and the first sub-state data and the correspondence between the i-th model parameter and the second sub-state data, obtain the correspondence between the i-th model parameter and the state data of the power battery.

[0027] According to the above technical means, the correlation between the model parameters of the equivalent circuit corresponding to the power battery and the status data of the power battery is established, and the corresponding relationship between each model parameter and the status data of the power battery is obtained, which is convenient for subsequently determining the reference correction coefficient of the power battery in actual use according to the corresponding relationship, and estimating the second available power.

[0028] The embodiment of the present application provides a power determination device for a power battery, characterized by comprising:

[0029] A first acquisition module, used for acquiring first state data of the power battery if the vehicle is in a driving condition;

[0030] a first determining module, configured to determine a first available power of the power battery according to the first state data and a pre-established power mapping table;

[0031] a second determining module, configured to determine second state data of the power battery according to a correspondence between the first state data, a model parameter of an equivalent circuit corresponding to the power battery, and the state data of the power battery;

[0032] The third determination module is used to correct the first available power based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery.

[0033] The present application provides a power determination device for a power battery, including:

[0034] A memory, used to store a power determination instruction of a power battery;

[0035] The processor is used to implement the method provided in the embodiment of the present application when executing the executable power battery power determination instruction stored in the memory.

[0036] An embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. The computer-executable instructions are configured to execute the above-mentioned method for determining the power of a power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of a flow chart of a method for determining power of a power battery provided in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of a second-order RC circuit corresponding to a power battery provided in an embodiment of the present application;

[0039] Figure 3 A flowchart illustrating a method for calculating power of a power battery of a new energy vehicle provided in an embodiment of the present application;

[0040] Figure 4 A schematic diagram of a process for obtaining a basic full-power map table provided in an embodiment of the present application;

[0041] Figure 5 A schematic diagram of a flow chart of a power correction method based on a SOH strategy provided in an embodiment of the present application;

[0042] Figure 6A schematic flow chart of a method for online estimating the maximum available power of a power battery provided in an embodiment of the present application;

[0043] Figure 7 A schematic flow chart of a method for creating a correspondence between second-order RC model parameters and power battery parameters provided in an embodiment of the present application;

[0044] Figure 8 A schematic diagram of the structure of a power determination device for a power battery provided in an embodiment of the present application;

[0045] Fig. 9 A schematic diagram of the composition structure of a power determination device for a power battery provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0047] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0048] In the following description, reference is made to “some embodiments\other embodiments”, which describe a subset of all possible embodiments, but it can be understood that “some embodiments\other embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0049] In the following description, the terms "first\second\third\fourth" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third\fourth" can be interchanged in a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0051] At present, the common power calibration methods mainly include the test power method, the fixed current method and the test current method. The test efficiency and calculation convenience are: the fixed current method > the test current method > the test power method, and the power accuracy is: the fixed current method < the test current method < the test power method. Among them, the power battery industry often uses the test current method at the single-cell level. After obtaining the DCR, the current (I) and power (P) are calculated. The advantage is that the power value under different states of charge (State of Charge, SOC), temperature and cut-off voltage can be calculated from the DCR value. This method assumes that the internal resistance is constant with the change of SOC, which will cause certain errors in the calculation of the power value. The whole package level mostly uses the test power method to accept the power capability. The advantage is that the target power value can be obtained directly, and the disadvantage is that the test time is long. Moreover, the above methods all adjust the SOC value of the power battery assembly to the target state in advance, and then conduct a current test or a power test after standing for a certain period of time. This method determines the battery health status (State of Health, SOH) strategy based on the test results obtained by the offline test method. The actual vehicle operating conditions are quite different from the test conditions and there is no clear conversion relationship, resulting in a large deviation between the SOH strategy obtained offline and the actual capacity and power attenuation. The actual vehicle operating conditions are quite different from the test conditions and there is no clear conversion relationship, resulting in a large deviation between the SOH strategy obtained offline and the actual capacity and power attenuation.

[0052] In the related technology, a method for estimating the power state (SOP) of the battery system by BMS regarding switching between peak and continuous power mainly focuses on the switching strategy between peak power and continuous power of new energy vehicles. However, the entire process mainly relies on the power map obtained by offline calibration in the BMS strategy. The entire strategy relies on the peak power and sustainable power signals in the BMS. When the peak power and sustainable power values ​​deviate from the actual capabilities, the vehicle will trigger pre-undervoltage and pre-overvoltage faults, resulting in power limitation or even power loss.

[0053] Based on the problems existing in the related art, the embodiment of the present application provides a method for determining the power of a power battery, which can obtain the maximum available power close to the actual power capacity of the power battery, thereby ensuring the safety and power of the vehicle. Figure 1 FIG. 1 is a flow chart of a method for determining power of a power battery provided in an embodiment of the present application, the method comprising the following steps:

[0054] S101. If the vehicle is in a driving condition, obtain first state data of a power battery of the new energy vehicle.

[0055] It should be noted that the vehicle can be a new energy vehicle or an electric vehicle, the driving condition can be that the vehicle is currently in an acceleration, deceleration, constant speed driving, turning and other driving states, and the first state data can be the surface temperature, SOC, etc. of the vehicle's power battery obtained during the driving process.

[0056] In some embodiments, when the vehicle is in a driving condition, the power battery may be in a discharging state or a charging state. The surface temperature of the power battery when the surface temperature reaches stability can be obtained through the vehicle's temperature sensor, and the remaining capacity of the power battery at the same time or in the same time period can be detected, and the SOC of the power battery can be determined based on the remaining capacity.

[0057] S102: Determine a first available power of the power battery according to the first state data and a pre-established power mapping table.

[0058] In some embodiments, the power mapping table may be the maximum available power corresponding to different state data obtained after testing the power battery during the development or testing phase of the power battery. The different state data may be the surface temperature and SOC of the battery determined under the test environment, that is, the power mapping table may include the battery temperature, SOC and the corresponding maximum available power.

[0059] In some embodiments, the first available power may be the maximum available power determined by the battery under the first state data, and the first available power may be the theoretical maximum available power determined according to the first state data and the power mapping table. In implementation, the first state data may be compared with the state data in the power mapping table, and if the power mapping table contains reference state data identical to the first state data, the maximum available power corresponding to the parameter state data may be determined as the first available power.

[0060] S103 . Determine second state data of the power battery according to a correspondence between the first state data, a model parameter of an equivalent circuit corresponding to the power battery, and the state data of the power battery.

[0061] In some embodiments, Figure 2 As shown, the equivalent circuit corresponding to the power battery can be a second-order RC circuit corresponding to the single cell of the power battery, wherein U1 represents the terminal voltage value of the single cell, I represents the current value, R1 represents the ohmic internal resistance, and R p1 and R p2 Represents the polarization resistance of a single cell, C p1 and C p2 Represents the polarization capacitance of a single cell, U OCV represents the open circuit voltage. The second-order RC circuit satisfies the relationship (1):

[0062]

[0063] Among them, U OCV Represents the polarization voltage.

[0064] In some embodiments, the model parameters of the power battery corresponding to the equivalent circuit may include polarization resistance, polarization capacitance, open circuit voltage, ohmic internal resistance, etc. of the equivalent circuit. The corresponding relationship between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery may include the corresponding relationship between each model parameter and the SOC, current, and initial polarization voltage of the power battery, that is, including the corresponding relationship between polarization resistance and SOC, rate, and initial polarization voltage, the corresponding relationship between polarization capacitance and SOC, current, and initial polarization voltage, the corresponding relationship between open circuit voltage and SOC, current, and initial polarization voltage, and the corresponding relationship between ohmic internal resistance and SOC, current, and initial polarization voltage.

[0065] In some embodiments, the correspondence between the model parameters of the power battery corresponding to the equivalent circuit and the status data of the power battery can be established by establishing the correspondence between each model parameter and the SOC, current, and initial polarization voltage of the power battery during the development stage, or the testing stage, or after the single cell that is normally offline undergoes a charge and discharge test.

[0066] In some embodiments, the second state data may include the actual ohmic internal resistance of the power battery, the battery capacity, etc., and the second state data of the power battery may be determined based on the current current, SOC and initial polarization voltage of the power battery when the vehicle is in the driving condition, and the correspondence between the model parameters of the equivalent circuit of the power battery obtained in advance and the state data of the power battery. For example, if the ohmic internal resistance R of the battery is obtained through an offline test and the current I, the state of charge S, the initial polarization voltage U p0 The fitting relationship is formula (2):

[0067] R(I,S,U p0 )=-aI-bS-cU p0 +C (2);

[0068] Where a, b, and c are the current I, state of charge S, and initial polarization voltage U, respectively. p0 The coefficient of C represents the capacity of the battery. The ohmic internal resistance R of the power battery can be calculated according to the current SOC of the power battery, the initial polarization voltage and formula (2).

[0069] S104 . Correct the first available power based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery.

[0070] In some embodiments, the first target available power may be the target maximum available power of the power battery. The first available power may be corrected or updated based on the second state data and a preset power correction parameter to obtain the first target available power. The preset power correction parameter may be a power correction parameter in an offline SOH parameter table in a BMS strategy. A reference power correction coefficient of the power battery during use may be determined based on the second state data, and the first available power may be corrected or updated in combination with the reference power correction coefficient and the preset correction parameter to obtain the first target available power.

[0071] In some embodiments, a target power correction coefficient can be determined based on the size relationship between a reference power correction coefficient determined by the second state data and a preset power correction coefficient, and then the first available power is corrected using the target power correction coefficient to obtain a first target available power.

[0072] In some embodiments, after obtaining the first available power, the state of the vehicle can also be judged. If it is determined that the vehicle is currently in a normal driving state, but the pre-undervoltage / pre-overvoltage, pre-overcurrent or vehicle fault alarm is triggered, the first available power can be corrected based on the BMS power limitation strategy to obtain the corrected available power. Thereafter, the corrected first available power is corrected based on the second state data and the preset power correction parameters to obtain the first target available power of the power battery.

[0073] In some embodiments, if the vehicle is in normal driving, but at least one of pre-undervoltage / pre-overvoltage, pre-overcurrent or vehicle fault alarm occurs, the first available power can be corrected using the corresponding BMS power limitation strategy. Exemplarily, if the vehicle is currently in a normal driving state and only pre-undervoltage / pre-overvoltage is triggered, the first available power can be corrected based on the pre-undervoltage / pre-overvoltage power limitation strategy of the BMS; if the vehicle is currently in a normal driving state and only pre-overcurrent is triggered, the first available power can be corrected based on the pre-overcurrent limitation strategy of the BMS; if the vehicle is currently in a normal driving state, but there is a fault alarm of the whole vehicle, the first available power can be corrected based on the vehicle fault alarm power limitation strategy of the BMS; if the vehicle is currently in a normal driving state, and pre-undervoltage / pre-overvoltage, pre-overcurrent and vehicle fault alarm are triggered at the same time, the first available power can be corrected based on the pre-undervoltage / pre-overvoltage power limitation strategy of the BMS, the pre-overcurrent power limitation strategy of the BMS and the vehicle fault alarm power limitation strategy of the BMS.

[0074] In the embodiment of the present application, if the vehicle is in a driving condition, the first state data of the power battery of the vehicle is obtained; according to the first state data and the pre-established power mapping table, the first available power of the power battery is determined; according to the correspondence between the first state data, the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery, the second state data of the power battery is determined; based on the second state data and the preset power correction parameter, the first available power is corrected to obtain the first target available power of the power battery. In this way, the actual second state data of the power battery can be determined by the first state data obtained by the vehicle under the driving condition, and the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery. Further, the first available power is corrected according to the second state data and the preset power correction parameter, and the influence of the second state data of the power battery on the maximum available power during actual use of the power battery is considered, so that the obtained first target available power is close to the actual power capacity of the power battery, ensuring the safety and power of the vehicle.

[0075] In some embodiments of the present application, the first available power is corrected based on the second state data and the preset power correction parameters to obtain the first target available power of the power battery, that is, the above-mentioned step S104 can be implemented by the following steps S1041 to S1043, and each step is described separately below.

[0076] S1041. Determine a reference power correction parameter according to the second state data.

[0077] It should be noted that the reference power correction parameter is different from the preset power correction parameter. The reference power correction parameter is not obtained offline, but is a power correction parameter determined according to the current state data of the power battery (second state data) during vehicle driving. When the power battery is in the same operating condition (such as pulse charging, pulse discharging, etc.), the reference power correction parameter and the corresponding preset power correction parameter may be the same or different.

[0078] In some embodiments, the second state data may be the ohmic internal resistance or discharge capacity of the power battery. When the vehicle is in a driving condition, if the power battery is in a DC charging or a pulse charging condition, the second state data may be the discharge capacity of the power battery. The discharge capacity may be estimated online based on the discharge efficiency and the charging capacity of the power battery. The reference power correction parameter may be determined based on the estimated discharge capacity. For example, the discharge capacity value of the battery may be determined as the reference power correction parameter. If the power battery is in a pulse discharge condition, the second state data may be the ohmic internal resistance of the power battery. The reference power correction parameter may be determined based on the ohmic internal resistance of the power battery. For example, the inverse of the ohmic internal resistance may be determined as the reference power correction parameter.

[0079] S1042: Determine a target power correction parameter based on a reference power correction parameter and a preset power correction parameter.

[0080] In some embodiments, the reference power correction parameter and the preset power correction parameter can be compared, and the target power correction parameter can be determined based on the size relationship between the reference power correction parameter and the preset power correction parameter. In implementation, the absolute value of the difference between the preset power correction parameter and the reference power correction parameter can be determined; if the absolute value of the difference is less than a preset threshold, the average value of the preset power correction parameter and the reference power correction parameter is determined as the target power correction parameter. The average value of the preset power correction parameter and the reference power correction parameter can be the arithmetic mean, weighted mean, square mean, etc. of the preset power correction parameter and the reference power correction parameter, and the preset threshold can be a pre-set power value.

[0081] According to the above technical means, if the absolute value of the difference between the preset power correction parameter and the reference power correction parameter is less than the preset threshold value, it means that the preset power correction parameter and the reference power correction parameter are relatively close. By combining the preset power correction parameter determined offline and the reference power correction parameter determined according to the second state data of the battery during actual use of the power battery, the determined target power correction parameter can be made more reasonable, thereby improving the accuracy of the maximum available power of the power battery.

[0082] In other embodiments, if the absolute value of the difference between the preset power correction parameter and the reference power correction parameter is greater than a preset threshold, the preset power correction parameter is determined as the target maximum available power. In this case, the difference between the reference power correction parameter and the preset power correction parameter is large, and the preset power correction parameter may be greater than the reference power correction parameter, or may be less than the reference power correction parameter. In this way, if the absolute value of the difference between the preset power correction parameter and the reference power correction parameter is greater than the preset threshold, it means that the reference power correction parameter determined by the actual second state data of the power battery may be wrong. At this time, using the preset power correction parameter as the target power correction parameter can prevent the target power correction parameter from having excessive deviations, thereby ensuring safe driving of the vehicle.

[0083] In some embodiments, the reference power correction parameter (determined by discharge capacity) corresponding to the power battery in pulse charging or DC charging is different from the reference power correction parameter (determined by ohmic internal resistance) corresponding to the power battery in pulse discharging, the preset power correction parameter corresponding to the power battery in pulse charging or DC charging may be different from the preset power correction parameter corresponding to the power battery in pulse discharging, and the preset threshold corresponding to the power battery in pulse charging or DC charging may be different from the preset threshold corresponding to the power battery in pulse discharging. Therefore, in implementation, it is necessary to determine the corresponding reference power correction parameter, preset power correction parameter, preset threshold and target power correction parameter in combination with the charging and discharging state of the power battery.

[0084] S1043: Correct the first available power based on the target power correction parameter to obtain a first target available power.

[0085] In some embodiments, the first power may be multiplied by the target power correction parameter to obtain the first target available power, or the first available power may be divided by the target power correction parameter to obtain the first target available power. The method of correcting the first available power based on the target power correction parameter is merely an exemplary description, and the present application does not limit this.

[0086] According to the above technical means, the target power correction parameter is determined according to the reference power parameter determined by the second state data of the power battery and the preset power correction parameter, and the target correction parameter can be determined for the attenuation level of the actual vehicle by combining offline calibration with online estimation. The theoretical maximum available power of the power battery can be corrected in real time based on the target power correction parameter, which can avoid the preset power correction parameter determined offline being too strict and affecting the actual user experience.

[0087] In some embodiments of the present application, after the first target available power of the power battery is obtained, the following steps S201 to S202 may also be performed, and each step is described below.

[0088] S201: When the power battery is in a low state of charge, estimate a second available power of the power battery based on a corresponding relationship between a model parameter of an equivalent circuit corresponding to the power battery and state data of the power battery.

[0089] In some embodiments, the power battery is in a low SOC state when the percentage of the current remaining capacity of the power battery to the rated capacity of the battery is lower than a preset percentage, which may be 30%, 20%, etc. Whether the power battery is in a low SOC state may be comprehensively determined based on the power performance of the power battery, the power demand of the vehicle, and the test calibration. When it is determined that the power battery is in a low state of charge, the current actual maximum available power of the power battery may be further estimated based on the corresponding relationship between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery to obtain the second available power.

[0090] In some embodiments, in the process of estimating the second available power of the power battery based on the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the status data of the power battery, the third state data of the power battery in a low charge state can be determined; the second available power is determined based on the third state data and the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the status data of the power battery.

[0091] In some embodiments, the third state data is different from the first state data and the second state data, and the third state data may be the SOC value, polarization voltage and current of the power battery in a low state of charge, etc. The second available power may be calculated by combining the SOC value, polarization voltage and current in a low state of charge, and the corresponding relationship between the model parameters of the corresponding equivalent circuit of the power battery and the state data of the power battery.

[0092] For example, after determining the current SOC value, polarization voltage and current of the power battery, the ohmic internal resistance of the power battery in the current state can be calculated by the corresponding relationship between the ohmic internal resistance in the second-order RC circuit of the power battery and the SOC, current and initial polarization voltage of the power battery (Formula (2)). Further, Formula (3) can be obtained according to Formula (1):

[0093] U1=U ocv -U p -IR1 (3)

[0094] In the process of calculating the second available power, U1 in formula (3) can be determined as the first-level pre-undervoltage voltage cutoff value, thereby obtaining the maximum current I max , according to the maximum current I max and the ohmic internal resistance to obtain the maximum available power (the second available power).

[0095] According to the above technical means, combined with the third state data of the power battery in a low charge state, and the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery, it is possible to estimate the maximum available power of the power battery according to the real-time state of the power battery, and obtain a second available power that is closer to the actual maximum available power.

[0096] S202: Determine a second target available power of the power battery based on the first target available power and the second available power.

[0097] In some embodiments, the second target available power may be the same as or different from the first target available power. In implementation, the second target available power may be determined according to the magnitude relationship between the first target available power and the second available power.

[0098] In some embodiments, in the process of estimating the second available power of the power battery based on the correspondence between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery, if the first target available power is less than the second available power, the first target available power can be determined as the second target power; if the first target available power is greater than the second available power, the second available power can be determined as the second target power; if the first target available power is equal to the second available power, the first target available power or the second available power can be determined as the second target power. By determining the smaller value of the first target available power and the second available power as the second target available power, a large deviation can be avoided while ensuring that the determined maximum available power is close to the actual power capacity of the power battery, thereby ensuring the safety of vehicle driving.

[0099] According to the above technical means, the second target available power is determined by combining the first target available power after the power battery SOH is corrected and the second available power estimated based on the status data of the power battery in a low charge state. The influence of the status data of the power battery during use on the maximum available power is taken into account, so that the maximum available power that meets the actual working conditions can be obtained.

[0100] In some embodiments of the present application, the process of creating the power mapping table in step S102 may be implemented through the following steps S301 to S304, and each step is described below.

[0101] S301 , testing a single cell of a power battery by using a current test method to obtain a corresponding relationship between a first property parameter and a second property parameter of the single cell.

[0102] It should be noted that the first attribute parameter and the second attribute parameter are different. The first attribute parameter may be the SOC and temperature of the single cell, and the second attribute parameter may be the ohmic internal resistance of the single cell. In the process of testing the single cell, the ohmic internal resistance of the single cell at different SOCs and the ohmic internal resistance at different temperatures may be determined respectively, and then the corresponding relationship between SOC, temperature and ohmic internal resistance may be obtained based on the ohmic internal resistance at different SOCs and the ohmic internal resistance at different temperatures.

[0103] In some embodiments, in the process of testing the single cells of the power battery using the test current method to obtain the correspondence between the first attribute parameter and the second attribute parameter of the single cell, the single cell can be adjusted to a specific first attribute parameter, and a pulse discharge test can be performed on the single cell to obtain a specific second attribute parameter corresponding to the specific first attribute parameter; the specific first attribute parameter and the specific second attribute parameter can be fitted to obtain the correspondence between the first attribute parameter and the second attribute parameter of the single cell.

[0104] In some embodiments, the specific first attribute parameter may be any selected temperature and SOC, and the specific second attribute parameter may be the corresponding ohmic internal resistance determined according to the selected arbitrary temperature and SOC. There may be multiple specific first attribute parameters, and by fitting multiple specific first attribute parameters and corresponding specific second attribute parameters, the corresponding ohmic internal resistance under the full temperature range and full SOC can be obtained, that is, the corresponding relationship between the first attribute parameter and the second attribute parameter can be obtained.

[0105] In some embodiments, if the specific first attribute parameter is SOC, the SOC and the corresponding ohmic internal resistance can be processed by a linear difference method to obtain the ohmic internal resistance under the full SOC; if the specific first attribute parameter is temperature, the ohmic internal resistance under the full temperature range can be determined by formula (4)-Arrhenius formula:

[0106]

[0107] Among them, K is the reaction rate constant, A is the pre-exponential factor, Ea is the apparent activation energy, R is the molar gas constant, T is the thermodynamic temperature, C is a constant, P is the power, and DCR is the ohmic internal resistance. By fitting the relationship between Ln (1 / DCR) and 1 / T, the ohmic internal resistance value at any temperature can be calculated.

[0108] According to the above technical means, the correspondence between the first attribute parameter and the second attribute parameter of the single cell of the power battery can be obtained, so as to facilitate the subsequent determination of the maximum available power of the single cell according to the correspondence, thereby providing a basic condition for determining the maximum available power of the power battery.

[0109] S302: Determine a third available power of the single battery cell according to the corresponding relationship between the first attribute parameter and the second attribute parameter.

[0110] In some embodiments, the actual maximum current and ohmic internal resistance of the single cell can be determined according to the corresponding relationship between SOC, temperature and ohmic internal resistance, and the third available power can be calculated according to the maximum current and ohmic internal resistance. For example, the actual maximum current I of the single cell can be determined according to formula (5): max :

[0111]

[0112] Among them, U ocv is the open circuit voltage at the current SOC, U min is the primary undervoltage value of the battery cell. max Exceeding the maximum current allowed by the winding core and mechanical parts, that is, the maximum current allowed by the winding core and mechanical parts shall prevail. After determining the maximum current, the third available power P1 can be calculated by formula (6):

[0113] P1=(U ocv -I max *DCR)*I max (6);

[0114] S303: Determine a fourth available power of the power battery based on the third available power and the series-parallel coefficient of the power battery.

[0115] In some embodiments, the third available power is the maximum available power of a single cell of the power battery, and the power battery includes multiple single cells connected in series and / or in parallel. Therefore, after determining the third available power corresponding to the single cell, the fourth available power of the power battery can be calculated by combining the third available power and the series-parallel coefficient. The fourth available power can be the maximum available power of the power battery. In implementation, the product of the third available power and the series-parallel coefficient of the entire power battery pack can be used as the fourth available power.

[0116] In some embodiments, the series-parallel coefficient may include the number of series connections, the number of parallel connections, and the discount coefficient of the single cell, wherein the discount coefficient may be determined based on factors such as the consistency of the cell internal resistance, the core temperature difference, the busbar resistance, the copper bar resistance (module and module, total positive and negative and high-voltage box, high-voltage box to high-voltage output), and the high-voltage harness resistance (high-voltage output to electric drive). In the process of determining the fourth available power, the product of the third available power and the number of series connections, the number of parallel connections, and the discount coefficient of the single cell may be used as the fourth available power.

[0117] S304: Create a power mapping table based on the first attribute parameter and the fourth available power.

[0118] In some embodiments, after determining the fourth available power, a power mapping table can be established based on the first attribute parameter and the corresponding fourth available power. The power mapping table can be a relationship mapping table between the SOC, temperature and maximum available power (fourth available power) of the power battery, and the SOC, temperature and corresponding maximum available power of each group of power batteries are recorded in the mapping table.

[0119] In some embodiments, in the process of creating a power mapping table based on the first attribute parameter and the fourth available power, the power battery can be verified based on the first attribute parameter using a power test method to obtain a verification result; the fourth available power is corrected based on the verification result to obtain a corrected available power; and a power mapping table is created based on the corrected available power and the first attribute parameter.

[0120] In some embodiments, in the process of verifying the power battery by using the power test method, the temperature and SOC can be given, and the power battery can be discharged for a fixed time at the fourth available power corresponding to the temperature and SOC to obtain the voltage value of the power battery, that is, the verification result; then, in the process of correcting the fourth available power based on the verification result, it can be determined whether the voltage value reaches the first level pre-undervoltage value. If it reaches the first level pre-undervoltage value, the first level pre-undervoltage power limit strategy of the BMS can be triggered to correct the fourth available power and obtain the corrected maximum available power; finally, a mapping table is created according to the first attribute parameter (SOC, temperature) and the corrected maximum available power. In this way, after the fourth available power of the whole pack of batteries is obtained by testing the single cell based on the current test method, the fourth available power that does not conform to the actual situation can be corrected by actually verifying the whole pack of batteries, thereby obtaining a more accurate maximum available power of the power battery and improving the accuracy of the power mapping table finally established.

[0121] According to the above technical means, the single cell is tested by the test current method to obtain the maximum available power of the single cell, and the maximum available power of the whole battery pack is calculated based on the maximum available power of the single cell. The power capacity of the power battery can be quickly obtained on the basis of ensuring accuracy, and the performance of the power battery can be evaluated.

[0122] In some embodiments of the present application, the model parameters of the power battery corresponding to the equivalent circuit include multiple, and the state data of the power battery includes first sub-state data and second sub-state data. The first sub-state data may be the current and SOC of the power battery, and the second sub-state data may be the initial polarization voltage of the power battery. Based on this, the correspondence between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery may be realized through the following steps S401 to S403, and each step is described below.

[0123] S401 . Perform a first charge and discharge test on a single cell of a power battery to obtain a corresponding relationship between an i-th model parameter and first sub-state data.

[0124] It should be noted that i is a positive integer greater than 0, and i is less than or equal to the total number of model parameters. When the model parameters include polarization capacitance, polarization resistance, ohmic internal resistance, and open circuit voltage, the i-th model parameter may be any one of polarization capacitance, polarization resistance, ohmic internal resistance, and open circuit voltage.

[0125] In some embodiments, during the first charge and discharge test of a single cell of a power battery, the discharge data of the single cell at different currents and different SOCs can be determined. The discharge data can be the i-th model parameter. Then, the relationship between the current, SOC and model parameters is fitted to obtain the corresponding relationship between the i-th model parameter and the current and SOC.

[0126] S402 , performing a second charge and discharge test on the single cell to obtain a corresponding relationship between the i th model parameter and the second sub-state data.

[0127] In some embodiments, the second charge and discharge test is different from the first charge and discharge test. The single cell can be charged or discharged with different currents to establish different initial polarization voltages. The relationship between the initial polarization voltage and the model parameters is then fitted to obtain the corresponding relationship between the i-th model parameter and the initial polarization voltage.

[0128] S403 . Obtain a corresponding relationship between the ith model parameter and the state data of the power battery based on a corresponding relationship between the ith model parameter and the first sub-state data and a corresponding relationship between the ith model parameter and the second sub-state data.

[0129] In some embodiments, after obtaining the correspondence between the i-th model parameter and the first sub-state data, and the correspondence between the i-th model parameter and the second sub-state data, these two correspondences can be analyzed separately and combined to determine the correspondence between the SOC, current, initial polarization voltage and the i-th model parameter of the power battery.

[0130] According to the above technical means, the correlation between the model parameters of the equivalent circuit corresponding to the power battery and the status data of the power battery is established, and the corresponding relationship between each model parameter and the status data of the power battery is obtained, which is convenient for subsequently determining the reference correction coefficient of the power battery in actual use according to the corresponding relationship, and estimating the second available power.

[0131] In the embodiment of the present application, if the vehicle is in a driving condition, the first state data of the power battery of the vehicle is obtained; according to the first state data and the pre-established power mapping table, the first available power of the power battery is determined; according to the correspondence between the first state data, the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery, the second state data of the power battery is determined; based on the second state data and the preset power correction parameter, the first available power is corrected to obtain the first target available power of the power battery. In this way, the actual second state data of the power battery can be determined by the first state data obtained by the vehicle under the driving condition, and the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery. Further, the first available power is corrected according to the second state data and the preset power correction parameter, and the influence of the second state data of the power battery on the maximum available power during actual use of the power battery is considered, so that the obtained first target available power is close to the actual power capacity of the power battery, ensuring the safety and power of the vehicle.

[0132] Next, the implementation process of the application embodiment in the actual application scenario is introduced.

[0133] Figure 3 A flowchart of a method for calculating the power of a new energy vehicle power battery provided in an embodiment of the present application is provided. The method can be implemented through the following steps S501 to S511, and each step is described separately below.

[0134] S501. Determine whether the new energy vehicle is in a driving condition.

[0135] If the vehicle is not in driving condition, the process ends; otherwise, step S502 to step S511 are executed.

[0136] S502: Look up the basic full power Map table (equivalent to the "power mapping table" in other embodiments) to confirm P0 (equivalent to the "first available power" in other embodiments).

[0137] According to the current SOC and T values, the corresponding power is found from the basic full power map. Figure 4 As shown, the basic full power Map table can be obtained through steps S601 to S605, and each step is described below.

[0138] S601. Obtain the DC internal resistance DCR (equivalent to the "second attribute parameter" in other embodiments) of the battery cell at a typical temperature and SOC (equivalent to the "first attribute parameter" in other embodiments) by a current test method.

[0139] Select a single cell that is normally offline for pulse discharge test, adjust the cell SOC to a fixed value and place it in a temperature box until the temperature is in equilibrium state T, discharge it with a certain current I for t time, when the discharge time is less than t, the cut-off voltage Umin is reached, reduce the current and discharge again, when the discharge time is greater than t, the cut-off voltage Umin is reached, increase the current and discharge again, until the cut-off voltage Umin is reached in just t time, use formula (7) to calculate the ohmic internal resistance value at this SOC and temperature T, and so on, you can get the ohmic internal resistance value at typical SOC and temperature, including but not limited to -10℃, 0℃, 25℃, 40℃ corresponding to each SOC point, SOC point including but not limited to SOCmin, 5% SOC, 10% SOC, 50% OC, 90% SOC, SOCmax. If the current I exceeds the maximum current allowed by the winding core and mechanical parts, test with the current limit value I.

[0140]

[0141] S602. Derive the DCR Map table of the core at all temperatures and all SOCs.

[0142] In this step, the DCR of the full SOC and full temperature range can be derived from the ohmic internal resistance value at the typical SOC and temperature T. The DCR between different SOCs can be directly linearly interpolated. The DCR between different temperatures conforms to the principle of the Arrhenius formula. The relationship between Ln(1 / DCR) and 1 / T can be fitted by formula (3) to calculate the ohmic internal resistance value at any temperature. Based on the DCR of the full SOC and full temperature range, a DCR Map table of the battery cell at full temperature and full SOC can be established (equivalent to the "correspondence between the first attribute parameter and the second attribute parameter of the single battery cell" in other embodiments).

[0143] S603, derive the current map table of the conductive core.

[0144] In this step, the maximum current Imax can be derived by formula (5) to obtain the maximum current Imax of the single cell at different temperatures and SOCs. Based on the temperature, SOC and the current Imax of the single cell, the current map of the cell can be established.

[0145] S604: derive a power map of the core.

[0146] In this step, the maximum available power can be derived through formula (6) to obtain the maximum available power of the single cell at different temperatures and SOCs (equivalent to the "third available power of the single cell" in other embodiments). Based on the temperature, SOC and the maximum available power of the single cell, a power map of the cell can be established.

[0147] S605: derive a power map of the entire battery pack.

[0148] In this step, the maximum available power of the whole pack of batteries is calculated based on the number of batteries in series and parallel and the discount factor, that is, the maximum available power P = P 电芯 * number of series * number of parallel * discount coefficient (equivalent to "determining the fourth available power of the power battery based on the third available power and the series-parallel coefficient of the power battery" in other embodiments), where P 电芯 Indicates the maximum available power of the single cell obtained in step S604. The discount coefficient needs to take into account the consistency of the cell internal resistance, the temperature difference of the winding core, the busbar resistance, the copper bar resistance (module and module, total positive and negative and high-voltage box, high-voltage box to high-voltage output) and the high-voltage harness resistance (high-voltage output to electric drive). Through this step, the maximum available power of the whole pack of batteries under different temperatures and SOCs can be obtained, thereby establishing the basic full power map of the whole pack of batteries.

[0149] After obtaining the basic full-power Map table for the entire pack of batteries, the basic full-power Map table can also be subjected to a test power positive verification, that is, at a specific SOC and temperature T, the entire pack of batteries is discharged at a specific maximum power for a fixed time to confirm whether the first-level pre-undervoltage strategy is triggered. If the first-level pre-undervoltage strategy is triggered, the power in the basic full-power Map table for the entire pack of batteries is corrected based on the strategy.

[0150] After step S502, if it is determined that the vehicle is in a normal driving state, the following steps may be performed:

[0151] S503: Determine whether at least one of a pre-undervoltage / pre-overvoltage, pre-overcurrent, and vehicle fault alarm is triggered.

[0152] If yes, then execute the following steps S504 to S505; otherwise, execute the following step S506. The order of judging whether to trigger the pre-undervoltage / pre-overvoltage, pre-overcurrent and vehicle fault alarm is not in particular order and can be performed in parallel.

[0153] S504 , limiting P0 based on the corresponding BMS power limiting strategy to obtain P1 .

[0154] In this step, if it is confirmed that pre-undervoltage / pre-overvoltage is triggered, P0 is limited based on the BMS pre-undervoltage / pre-overvoltage strategy to obtain P11; if it is confirmed that only pre-overcurrent is triggered, P0 is limited based on the BMS pre-undervoltage / pre-overvoltage strategy to obtain P12; if it is confirmed that only the vehicle fault alarm is triggered, P0 is limited based on the BMS vehicle fault alarm strategy to obtain P13. The pre-undervoltage strategy and pre-overcurrent strategy are voltage protection strategies with different gradients set according to the cell cut-off voltage, and different power batteries can be set according to performance and safety margins.

[0155] If the pre-undervoltage / pre-overvoltage, pre-overcurrent, and vehicle fault alarm are triggered at the same time, the three power limit strategies can be used in no particular order, and the minimum value of P11, P12, and P13 obtained by power limit can be determined as the final maximum available power P1; if only the pre-undervoltage / pre-overvoltage is triggered, P11 can be determined as P1; if only the pre-overcurrent is triggered, P12 can be determined as P1; if only the vehicle fault alarm is triggered, P13 can be determined as P1. If the pre-undervoltage / pre-overvoltage and pre-overcurrent are triggered, the smaller value of P11 and P12 can be determined as P1; if the pre-overcurrent and vehicle fault alarm are triggered, the smaller value of P12 and P13 can be determined as P1.

[0156] S505 . Modify P1 based on the SOH strategy to obtain P2.

[0157] like Figure 5 As shown, step S505 can be implemented through steps S5051 to S5057, and each step is described below.

[0158] S5051. Determine whether the vehicle is in a slow charging state.

[0159] If so, the process ends; otherwise, the following steps S5052 to S5058 are executed.

[0160] S5052: Determine whether the vehicle is in a DC charging or pulse charging state.

[0161] If so, execute the following steps S5053 and S5054a, or the following steps S5053 and S5054b; otherwise, execute step S5055.

[0162] S5053. Determine whether the difference between the charging correction coefficient in the offline SOH strategy table (equivalent to the "preset power correction parameter" in other embodiments) and the online charging attenuation coefficient (equivalent to the "reference power correction coefficient" in other embodiments) is less than the first threshold value X1 (equivalent to the "preset threshold value" in other embodiments).

[0163] If so, execute the following step S5054a; otherwise, execute the following step S5054b.

[0164] S5054a, based on the charging correction coefficient in the offline SOH strategy table and the average value of the online charging attenuation coefficient, P1 is corrected to obtain P2. That is, the attenuation coefficient is jointly determined by the offline SOH parameter table in the BMS strategy and the online predicted attenuation coefficient.

[0165] S5054b. Correct P1 based on the charging correction coefficient in the offline SOH strategy table to obtain P2.

[0166] This step shows that when the difference between the charging correction coefficient in the offline SOH strategy table and the online charging attenuation coefficient is greater than a given value X1, the online prediction may be biased and correction is performed based on the offline SOH strategy table.

[0167] The attenuation of DC charging current and pulse charging current is affected by the loss of active materials in the battery cell, the growth of SEI film, battery side reactions, etc., and shows the same trend as the attenuation of rated capacity. There is a certain relationship between discharge capacity, charging capacity, DCR and temperature, and the relationship between them can be fitted using basic battery cycle data. If the slow charging condition in the vehicle's operating conditions is certain, the discharge capacity can be estimated online based on the charging capacity, thereby calculating the attenuation of the rated capacity, and predicting the online rated capacity attenuation level.

[0168] S5055. Confirm whether the vehicle is in a pulse discharge state.

[0169] If so, execute the following steps S5056, S5057a, or S5056, S5057b; otherwise, end the process.

[0170] S5056. Confirm whether the difference between the discharge correction coefficient in the offline SOH strategy table (equivalent to the "preset power correction coefficient" in other embodiments) and the online discharge attenuation coefficient (equivalent to the "reference power correction coefficient" in other embodiments) is less than the second threshold value X2 (equivalent to the "preset threshold value" in other embodiments).

[0171] If yes, then execute the following step S5057a; otherwise, execute the following step S5057b. The second threshold value X2 can be determined comprehensively by the acceleration cycle, storage test, working condition test and vehicle reliability test.

[0172] S5057a. Correct P1 based on the discharge correction coefficient in the offline SOH strategy table and the average value of the online discharge attenuation coefficient to obtain P2.

[0173] In this step, the online discharge attenuation coefficient can be determined by the online predicted DCR, so the discharge SOH correction coefficient can be determined by the SOH correction table in the BMS strategy and the online predicted DCR. The theoretical basis of this correction strategy is that the pulse discharge power is limited by the discharge cut-off voltage, and the power capacity depends on the level of the ohmic internal resistance DCR. The online DCR prediction method can be obtained through the following steps S5071 to S5073.

[0174] S5057b. Correct P1 based on the discharge correction coefficient in the offline SOH strategy table to obtain P2.

[0175] Correction based on the offline SOH strategy combined with the real-time estimated DCR and tested battery capacity in the vehicle's operating conditions can greatly improve the user's vehicle experience throughout its life cycle.

[0176] S506: Modify P0 based on the SOH strategy to obtain P2.

[0177] S507: Determine whether the power battery is currently in a low charge state.

[0178] If so, execute the following steps S508, S509 and S510, or S508, S509 and S511; otherwise, execute the following step S511.

[0179] S508. Online estimation of maximum available power P3 (equivalent to the “second available power” in other embodiments).

[0180] like Figure 6 As shown, the maximum available power P3 can be estimated through the following steps S5081 to S5084, and each step is described below.

[0181] S5081. Obtain the current SOC of the power battery using the ampere-hour integration method.

[0182] S5082. Obtain the corresponding relationship between the second-order RC model parameters and the power battery parameters (equivalent to the “corresponding relationship between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery” in other embodiments).

[0183] like Figure 7 As shown, the correspondence between the second-order RC model parameters and the power battery parameters can be determined through steps S701 to S703.

[0184] S701 , obtaining the corresponding relationship between each parameter of the second-order RC model and the current I and SOC.

[0185] Among them, the parameters of the second-order RC model include the open circuit voltage U ocv , ohmic internal resistance R0, polarization internal resistance R p And polarization capacitance C p Etc. The corresponding relationship between the model parameters and current I and SOC can be determined through the following steps:

[0186] 1) Place the battery cell in a 25°C incubator and let it stand for 2 hours (h);

[0187] 2) Charge the cell with 1 / 3C current to the cut-off voltage Umax, then charge with constant voltage Umax until the current is less than 0.05C, and let stand for 30 minutes (min);

[0188] 3) Discharge the battery cell to 5% SOC with 1 / 3C current and let it stand for 2 hours;

[0189] 4) Discharge for 10 seconds (s) with the maximum current Imax in step S603, record the discharged capacity C1, and charge the capacity C1 with 1 / 3C, and let it stand for 30 minutes;

[0190] 5) Repeat step 4), reduce the current I and set different gradients, including different current values ​​in actual road conditions of new energy vehicles;

[0191] 6) Repeat steps 3) to 5) 20 times.

[0192] From the above steps, the voltage after standing for 2 hours at different SOC can be obtained: U ocv and SOC, U after standing under completely depolarized conditions ocv , the influence of current I can be ignored;

[0193] From the above steps, the discharge data of different currents under different SOCs can be used to obtain the basic data of ohmic internal resistance, SOC, and current I by step formula (7), and the corresponding relationship DCR (I, SOC) can be fitted by MATLAB.

[0194] From the above steps, the polarization voltage U under different conditions can be separated by the second-order RC model formula in step 4). p Based on Kirchhoff's law (polarization voltage as a function of time) formula (8) and using MATLAB, R can be fitted P1 , C P1 , R P2 and C P2 The specific value of .

[0195]

[0196] S702: Obtain the corresponding relationship between each parameter of the second-order RC model and the initial polarization voltage.

[0197] The corresponding relationship between the model parameters and the initial polarization voltage can be determined by the following steps:

[0198] 1) Place the battery cell in a 25°C incubator for 2 hours;

[0199] 2) Charge the cell with 1 / 3C current to the cut-off voltage Umax, then charge with constant voltage Umax until the current is less than 0.05C, and let stand for 30 minutes;

[0200] 3) Discharge the battery to different SOCs with 1 / 3C current and leave it for 2 hours;

[0201] 4) Charge with 0.5C current for 10s / 20s / 30s / 40s / 50s and let stand for 2h;

[0202] 5) Discharge with 1C / 2C / 3C / 4C / 5C current for 5s to establish polarization voltage;

[0203] 6) Discharge to the cut-off voltage using the maximum current Imax of step S603.

[0204] Through the above steps, the basic data of ohmic internal resistance and initial polarization voltage can be obtained, and the model relationship between the two can be fitted by MATLAB. Similarly, the relationship between polarization resistance, polarization capacitance and initial polarization voltage can be obtained.

[0205] S703 , obtaining the corresponding relationship between each parameter of the second-order RC model and the SOC, current and initial polarization voltage.

[0206] Combining the model relationship obtained in step S701 and step S702, the model parameters (open circuit voltage U ocv , ohmic internal resistance R0, polarization internal resistance R p And polarization capacitance C p ) and SOC, current and initial polarization voltage (U p0 ) model relationship, namely R(I,SOC,U p0 ), R p1 (I,SOC,U p0 ), R p2 (I,SOC,U p0 ), C p1 (I,SOC,U p0 ), C p2 (I,SOC,U p0 ).

[0207] S5083. Estimate the DC internal resistance based on the correspondence between the second-order RC model parameters and the power battery parameters and the actual SOC and current I.

[0208] Input any current I into the corresponding relationship between the second-order RC model parameters and the power battery parameters, and U can be calculated. OCV , R0, R p1 , R p2 , C p1 and C p2 For example, R and I, SOC, U can be obtained by offline testing. p0 The fitting relationship is R(I,SOC,U p0 )=-aI-bSOC-cU p0 +C, where a, b, c are all constants, C is the battery capacity, SOC, U p0According to the current battery status, it can be directly obtained. The DC internal resistance can be inferred by determining any current value. The initial polarization voltage Up0 is determined by the difference between the current dynamic voltage and the static voltage.

[0209] S5084: Perform online power estimation based on the DC internal resistance to obtain a maximum available power estimation value.

[0210] The maximum current when the terminal voltage U1 is the cut-off value of the first-level pre-undervoltage voltage can be calculated, thereby obtaining the estimated value of the maximum available power in this state.

[0211] S509 , determining whether the online estimated maximum available power P3 is less than the maximum available power P2 corrected based on the SOH strategy (equivalent to the “first target available power” in other embodiments).

[0212] If so, execute the following step S509; otherwise, execute the following step S510.

[0213] S510. Determine P3 as the target maximum available power (equivalent to the “second target available power” in other embodiments).

[0214] S511. Determine P2 as the target maximum available power.

[0215] Under low SOC conditions, the battery power is low and the DCR is large, resulting in a sharp drop in available power (more obvious under low temperature and low SOC conditions). At this time, the power value of the Map table is obtained by calibrating the steady-state condition using the offline test current or test power method, without considering the impact of the initial cumulative voltage on the available power. This causes the vehicle to frequently trigger a pre-undervoltage fault when used near the available power boundary. Therefore, for low SOC conditions, based on the traditional Map method, the available power can be corrected in combination with an online second-order RC model.

[0216] After obtaining the target maximum available power, when the actual power usage of the VCU or PCU exceeds the target maximum available power of the battery (SOP boundary capability), the BMS can actively limit the power to avoid undervoltage faults caused by long-term over-boundary use.

[0217] The power calculation method of the power battery of the new energy vehicle provided in the present application, combined with the power test method of the battery cell and the whole package, comprehensively utilizes the test current, test power, Arrhenius formula, etc., to provide an efficient and relatively accurate offline power test method, which is used as the basis of the power Map table lookup method; further, the relationship between each typical parameter and SOC, rate and polarization voltage in the second-order RC model is obtained through offline testing, which is used as the basis for online DCR and power estimation. On the one hand, DCR will gradually deteriorate during the use of new energy vehicles and thus affect the available discharge power. The SOH coefficient can be further corrected by using online DCR prediction; on the other hand, the accuracy of the maximum available power in actual use affects the user experience and safe driving of new energy vehicles. The maximum available power obtained by the BMS power Map table does not take into account the actual use conditions of new energy vehicles, and the initial cumulative activation brought by the continuous driving scene in the actual working conditions will bring a large deviation to the maximum available power, especially in the low charge state. Therefore, by performing online estimation and correction of the available power in the low charge state, the maximum available power of the new energy vehicle can be predicted more accurately, avoiding the problem of power limitation or even power loss caused by inaccurate estimation in actual use.

[0218] The present application provides a power determination device for a power battery. Figure 8 A schematic diagram of the structure of a power determination device for a power battery provided in an embodiment of the present application is shown in FIG. Figure 8 As shown, the power determination device 800 of the power battery includes:

[0219] A first acquisition module 801 is used to acquire first state data of the power battery if the vehicle is in a driving condition;

[0220] A first determining module 802, configured to determine a first available power of the power battery according to the first state data and a pre-established power mapping table;

[0221] A second determining module 803, configured to determine second state data of the power battery according to a correspondence between the first state data, a model parameter of an equivalent circuit corresponding to the power battery, and the state data of the power battery;

[0222] The third determination module 804 is configured to correct the first available power based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery.

[0223] In some embodiments, the third determination module 804 includes:

[0224] A first determining submodule, configured to determine a reference power correction parameter according to the second state data;

[0225] A second determination submodule, configured to determine a target power correction parameter based on the reference power correction parameter and the preset power correction parameter;

[0226] The first correction submodule is used to correct the first available power based on the target power correction parameter to obtain the first target available power.

[0227] In some embodiments, the first determining submodule includes:

[0228] A first determining unit, configured to determine an absolute value of a difference between the preset power correction parameter and a reference power correction parameter;

[0229] The second determining unit is configured to determine an average value of the preset power correction parameter and the reference power correction parameter as the target power correction parameter if the absolute value of the difference is less than a preset threshold.

[0230] In some embodiments, the first determining submodule further includes:

[0231] The third determining unit is configured to determine the preset power correction parameter as the target maximum available power if the absolute value of the difference is greater than the preset threshold.

[0232] In some embodiments, the power battery power determination device 800 further includes:

[0233] a first estimating module, configured to estimate, when the power battery is in a low state of charge, a second available power of the power battery based on a corresponding relationship between a model parameter of an equivalent circuit corresponding to the power battery and state data of the power battery;

[0234] The fourth determination module is used to determine a second target available power of the power battery based on the first target available power and the second available power.

[0235] In some embodiments, the fourth determining module includes:

[0236] a third determining submodule, configured to determine the first target available power as the second target power if the first target available power is less than the second available power;

[0237] a fourth determining submodule, configured to determine the second available power as the second target power if the first target available power is greater than the second available power;

[0238] A fifth determining submodule is configured to determine the first target available power or the second available power as the second target power if the first target available power is equal to the second available power.

[0239] In some embodiments, the first estimation module includes:

[0240] a sixth determining submodule, configured to determine third state data of the power battery being in a low charge state;

[0241] The seventh determination submodule is used to determine the second available power according to the third state data and the corresponding relationship between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery.

[0242] In some embodiments, the power battery power determination device 800 further includes:

[0243] A second acquisition module is used to test the single cell of the power battery by using a test current method to obtain a corresponding relationship between the first attribute parameter and the second attribute parameter of the single cell;

[0244] A fifth determining module, configured to determine a third available power of the single battery cell according to a corresponding relationship between the first attribute parameter and the second attribute parameter;

[0245] a sixth determining module, configured to determine a fourth available power of the power battery based on the third available power and a series-parallel coefficient of the power battery;

[0246] The first creation module is used to create the power mapping table based on the first attribute parameter and the fourth available power.

[0247] In some embodiments, the first creation module includes:

[0248] A first verification submodule, configured to verify the power battery by using a power test method based on the first attribute parameter to obtain a verification result;

[0249] A second correction submodule, used for correcting the fourth available power based on the verification result to obtain a corrected available power;

[0250] The first creation submodule is used to create the power mapping table based on the corrected available power and the first attribute parameter.

[0251] In some embodiments, the first acquisition module includes:

[0252] A first acquisition submodule is used to adjust the value of the single battery cell to a specific first attribute parameter, and perform a pulse discharge test on the single battery cell to obtain a specific second attribute parameter corresponding to the specific first attribute parameter;

[0253] The first fitting processing submodule is used to perform fitting processing on the specific first attribute parameter and the specific second attribute parameter to obtain a corresponding relationship between the first attribute parameter and the second attribute parameter of the single battery cell.

[0254] In some embodiments, the model parameters of the power battery corresponding to the equivalent circuit include multiple ones, the state data of the power battery includes first sub-state data and second sub-state data; the power determination device 800 of the power battery also includes:

[0255] a third acquisition module, configured to perform a first charge and discharge test on a single cell of the power battery to obtain a corresponding relationship between an i-th model parameter and the first sub-state data; wherein i is greater than 0 and less than or equal to the total number of model parameters;

[0256] a fourth acquisition module, configured to perform a second charge and discharge test on the single cell to obtain a corresponding relationship between the i-th model parameter and the second sub-state data;

[0257] A fifth acquisition module is used to obtain the correspondence between the i-th model parameter and the state data of the power battery based on the correspondence between the i-th model parameter and the first sub-state data and the correspondence between the i-th model parameter and the second sub-state data.

[0258] It should be noted that the description of the power determination device of the power battery in the embodiment of the present application is similar to the description of the corresponding method embodiment above, and has similar beneficial effects as the method embodiment, so it is not repeated here. For technical details not disclosed in the embodiment of the device, please refer to the description of the method embodiment of the present application for understanding.

[0259] It should be noted that in the embodiment of the present application, if the power determination method of the power battery described above is implemented in the form of a software function module and is sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application can be essentially or partly reflected in the form of a software product that contributes to the relevant solution. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a U disk, a mobile hard disk, a read-only memory (ROM), a disk or an optical disk. In this way, the embodiment of the present application is not limited to any specific combination of hardware and software.

[0260] Accordingly, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for determining the power of a power battery provided in the above embodiment is implemented.

[0261] An embodiment of the present application also provides a device for determining the power of a power battery. Fig. 9 A schematic diagram of the composition structure of a power determination device for a power battery provided in an embodiment of the present application is as follows: Fig. 9 As shown, the power battery power determination device 900 includes: a memory 901, a processor 902, a communication interface 903 and a communication bus 904. The memory 901 is used to store an executable power battery power determination instruction; the processor 902 is used to execute the executable power battery power determination instruction stored in the memory 901 to implement the power battery power determination method provided in the above embodiment.

[0262] The description of the power determination device and storage medium embodiment of the power battery is similar to the description of the method embodiment, and has similar beneficial effects as the method embodiment. For technical details not disclosed in the power determination device and storage medium embodiment of the power battery of the present application, please refer to the description of the method embodiment of the present application for understanding.

[0263] It should be noted that, in this article, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises at least one ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0264] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0265] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0266] In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0267] A person of ordinary skill in the art can understand that: all or part of the steps of implementing the above-mentioned method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above-mentioned method embodiment; and the aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROM, disks or optical disks.

[0268] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application can essentially or in other words, the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a product to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks or optical disks.

[0269] The above is only an implementation method of the present application, but the protection scope of the present application is not limited thereto. Any technical object familiar with the technical field can be easily conceived of within the technical scope disclosed in the present application. Changes or substitutions should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for determining the power of a power battery, characterized in that: include: If the vehicle is in a driving condition, obtaining first state data of a power battery of the vehicle; Determining a first available power of the power battery according to the first state data and a pre-established power mapping table; determining second state data of the power battery according to a correspondence between the first state data, a model parameter of an equivalent circuit corresponding to the power battery, and the state data of the power battery; The first available power is corrected based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery.

2. The method according to claim 1, characterized in that: The correcting the first available power based on the second state data and the preset power correction parameter to obtain the first target available power of the power battery includes: determining a reference power correction parameter according to the second state data; Determining a target power correction parameter based on the reference power correction parameter and the preset power correction parameter; The first available power is corrected based on the target power correction parameter to obtain the first target available power.

3. The method according to claim 2, characterized in that The determining of the target power correction parameter based on the reference power correction parameter and the preset power correction parameter includes: Determining an absolute value of a difference between the preset power correction parameter and a reference power correction parameter; If the absolute value of the difference is smaller than a preset threshold, an average value of the preset power correction parameter and the reference power correction parameter is determined as the target power correction parameter.

4. The method according to claim 3, characterized in that The method further comprises: If the absolute value of the difference is greater than the preset threshold, the preset power correction parameter is determined as the target maximum available power.

5. The method according to claim 1, characterized in that The method further comprises: When the power battery is in a low state of charge, estimating a second available power of the power battery based on a corresponding relationship between a model parameter of an equivalent circuit corresponding to the power battery and state data of the power battery; Based on the first target available power and the second available power, a second target available power of the power battery is determined.

6. The method according to claim 5, characterized in that The determining, based on the first target available power and the second available power, the second target available power of the power battery includes at least one of the following: If the first target available power is less than the second available power, determining the first target available power as the second target power; If the first target available power is greater than the second available power, determining the second available power as the second target power; If the first target available power is equal to the second available power, the first target available power or the second available power is determined as the second target power.

7. The method according to claim 5, characterized in that The estimating the second available power of the power battery based on the correspondence between the model parameters of the equivalent circuit corresponding to the power battery and the state data of the power battery includes: Determining third state data of the power battery in a low charge state; The second available power is determined according to the third state data and a corresponding relationship between a model parameter of an equivalent circuit corresponding to the power battery and the state data of the power battery.

8. The method according to claim 1, characterized in that The method further comprises: Testing the single cell of the power battery by using a current test method to obtain a corresponding relationship between a first property parameter and a second property parameter of the single cell; Determining a third available power of the single battery cell according to a corresponding relationship between the first attribute parameter and the second attribute parameter; Determining a fourth available power of the power battery based on the third available power and a series-parallel coefficient of the power battery; The power mapping table is created based on the first attribute parameter and the fourth available power.

9. The method according to claim 8, characterized in that The creating the power mapping table based on the first attribute parameter and the fourth available power includes: Based on the first property parameter, verifying the power battery using a power test method to obtain a verification result; Correcting the fourth available power based on the verification result to obtain corrected available power; The power mapping table is created based on the corrected available power and the first attribute parameter.

10. The method according to claim 8, characterized in that The method of testing the single cell of the power battery by using the current test method to obtain the corresponding relationship between the first property parameter and the second property parameter of the single cell includes: The single cell is adjusted to a specific first property parameter, and a pulse discharge test is performed on the single cell to obtain a specific second property parameter corresponding to the specific first property parameter; The specific first property parameter and the specific second property parameter are fitted to obtain a corresponding relationship between the first property parameter and the second property parameter of the single battery cell.

11. The method according to claim 1, characterized in that: The model parameters of the power battery corresponding to the equivalent circuit include a plurality of parameters, and the state data of the power battery includes first sub-state data and second sub-state data; The process of creating a corresponding relationship between the model parameters of the power battery corresponding to the equivalent circuit and the state data of the power battery includes: Performing a first charge and discharge test on a single cell of the power battery to obtain a corresponding relationship between an i-th model parameter and the first sub-state data; wherein i is greater than 0 and less than or equal to the total number of model parameters; Performing a second charge-discharge test on the single cell to obtain a corresponding relationship between the i-th model parameter and the second sub-state data; Based on the corresponding relationship between the i-th model parameter and the first sub-state data and the corresponding relationship between the i-th model parameter and the second sub-state data, the corresponding relationship between the i-th model parameter and the state data of the power battery is obtained.

12. A power determination device for a power battery, characterized in that: include: A first acquisition module, used for acquiring first state data of the power battery if the vehicle is in a driving condition; a first determining module, configured to determine a first available power of the power battery according to the first state data and a pre-established power mapping table; a second determining module, configured to determine second state data of the power battery according to a correspondence between the first state data, a model parameter of an equivalent circuit corresponding to the power battery, and the state data of the power battery; The third determination module is used to correct the first available power based on the second state data and a preset power correction parameter to obtain a first target available power of the power battery.

13. A power determination device for a power battery, characterized in that: include: processor and memory; wherein, The memory is used to store a computer program that can be run on the processor; The processor is configured to execute the method according to any one of claims 1 to 11 when running the computer program.

14. A computer-readable storage medium, characterized in that: The storage medium stores computer program code, and when the computer program code is executed by a computer, the method according to any one of claims 1 to 11 is executed.

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