Balancing Method, Device, Storage Medium and Electronic Device for Battery Hybrid Series-Parallel System

Abstract

The present invention discloses an equalization method, device, storage medium and electronic device for a battery hybrid system. The method includes: obtaining the SOC state of the single cells in the battery hybrid system; determining the equalization method for the single cells and the corresponding equalization target SOC according to the SOC of the single cells; determining the equalization capacity of the single cells according to the equalization target SOC, and calculating the equalization duration based on the equalization capacity. Based on the inconsistency problems between ternary and lithium iron phosphate single cells and between the same type of single cells, internal equalization of the same type of battery and external equalization of different types of batteries are realized, so as to realize the equalization control of the single cells. Under the condition of ensuring the normal travel of the hybrid electric vehicle, reasonable equalization management is carried out on the battery hybrid system, ensuring the safe driving of the vehicle while extending the service life of the battery.

Description

Technical Field

[0001] The present invention relates to the field of power battery control, and particularly to an equalization method, device, storage medium and electronic device for a battery hybrid system. Background Art

[0002] Ternary lithium batteries and lithium iron phosphate batteries are two types of power batteries commonly used in new energy vehicles at present. Ternary lithium batteries have the characteristics of high energy density, little influence by low temperature, and accurate prediction of SOC (State Of Charge, used to reflect the remaining capacity of the battery), while lithium iron phosphate batteries have the characteristics of more stable chemical properties, more charge and discharge cycles, and lower cost. The hybrid technology of ternary and lithium iron phosphate power batteries can combine the characteristics of both and give full play to their respective advantages.

[0003] As is well known, due to differences in internal materials and fine structures of the same type of monomer batteries when they leave the factory, there are inconsistencies in voltage, capacity, internal resistance, etc. between monomer batteries. Moreover, there are significant differences in materials and properties between the two types of batteries, which result in greater inconsistencies between the two types of batteries. And these inconsistencies will further increase with the cyclic charge and discharge of the battery pack. This not only accelerates the battery aging process but also causes phenomena such as overcharging and over-discharging of individual cells during the operation of electric vehicles, and even may lead to the risk of thermal runaway. Therefore, how to perform local charging or discharging on some monomer batteries to achieve the consistency management of lithium-ion battery packs, thereby effectively optimizing the battery pack inconsistency, improving the available charge and discharge capacity of the battery pack and the battery life, is an urgent problem to be solved in this field. Summary of the Invention

[0004] The equalization method, device, storage medium and electronic device for the battery hybrid system in the present invention achieve internal equalization of the same type of batteries and external equalization of different types of batteries, thereby realizing the equalization control of monomer batteries and improving the consistency of the battery pack. The specific solutions are as follows:

[0005] In a first aspect, an equalization method for a battery hybrid system is provided. The battery hybrid system includes ternary lithium batteries and lithium iron phosphate batteries. The method includes:

[0006] Obtain the SOC state of the monomer batteries in the battery hybrid system;

[0007] Determine the equalization method for the monomer battery and the corresponding equalization target SOC according to the SOC of the monomer battery;

[0008] Determine the equalization capacity of the monomer battery according to the equalization target SOC, and calculate the equalization duration according to the equalization capacity, so as to realize the equalization control of the monomer battery.

[0009] Further, if the SOC state of the single cell reaches the cut-off voltage, determining the equalization method of the single cell and the corresponding equalization target SOC according to the SOC of the single cell includes:

[0010] Determining the target cell type for which the equalization duration needs to be updated according to the type of the cut-off voltage and the type of the battery cell that reaches the cut-off voltage;

[0011] Determining the equalization capacity according to the external equalization target SOC of the target cell type.

[0012] Further, the method further includes:

[0013] For battery cells of other types except the target cell type, equalization is performed according to the historical equalization duration.

[0014] Further, if the type of the cut-off voltage is the charging cut-off voltage and the type of the battery cell that reaches the cut-off voltage is a ternary lithium battery, clear the historical equalization duration of all ternary single cells;

[0015] All the ternary single cells perform external equalization with the equalization duration corresponding to the equalization capacity of [(1 - a%) * SOH1 * C1], where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, and C1 is the battery capacity of the ternary lithium battery at 25°C.

[0016] Further, if the type of the cut-off voltage is the charging cut-off voltage and the type of the battery cell that reaches the cut-off voltage is a lithium iron phosphate battery, continue to perform equalization of all lithium iron single cells according to the corresponding historical equalization duration.

[0017] Further, if the type of the cut-off voltage is the discharging cut-off voltage, let Q1 = a% * SOH1 * C1, Q2 = 100% * SOH1 * C1, where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C;

[0018] If Q1 > Q2 and the type of the battery cell that reaches the cut-off voltage is a ternary lithium battery, then determine the target cell type as the lithium iron phosphate battery, and all lithium iron single cells perform external equalization with the equalization duration corresponding to the equalization capacity of Q1 - Q2;

[0019] If Q1 > Q2, and the type of battery cell that reaches the cut-off voltage is the lithium iron phosphate battery, then there is no such target battery type, and all lithium iron monomer batteries are balanced according to the historical equalization duration.

[0020] Further, the method further includes:

[0021] If Q1 < Q2, and the type of battery cell that reaches the cut-off voltage is the ternary lithium battery, then there is no such target battery type, and all ternary monomer batteries are balanced according to the historical equalization duration;

[0022] If Q1 < Q2, and the type of battery cell that reaches the cut-off voltage is the lithium iron phosphate battery, the target battery type is the ternary lithium battery, and all the ternary monomer batteries are externally balanced with the equalization duration corresponding to Q1 - Q2 as the equalization capacity.

[0023] Further, the method further includes:

[0024] If the static duration of the battery parallel-series system is greater than or equal to T, and the current after static is less than i, the method for determining the equalization method of the monomer battery according to the SOC of the monomer battery and the equalization target SOC corresponding to the equalization method include:

[0025] Judge whether all the monomer batteries meet the OCV correction condition according to the SOC of the monomer battery, and on this basis, determine the equalization method of the monomer batteries of different types and the equalization duration corresponding to the equalization method.

[0026] Further, if all the monomer batteries meet the OCV correction condition, determining the equalization method of the monomer batteries of different types and the equalization duration corresponding to the equalization method includes:

[0027] Calculate the battery capacity gap of the ternary lithium battery after internal equalization of the ternary lithium battery according to the ternary internal equalization target SOC of the ternary lithium battery, and the battery capacity gap of the lithium iron phosphate battery after internal equalization of the lithium iron phosphate battery according to the lithium iron internal equalization target SOC of the lithium iron phosphate battery;

[0028] Determine the equalization methods of the ternary lithium battery and the lithium iron phosphate battery according to the magnitude relationship between the battery capacity gap of the ternary lithium battery and the battery capacity gap of the lithium iron phosphate battery.

[0029] Further, the ternary internal equilibrium target SOC is the maximum single-cell SOC when the internal inconsistency of the ternary lithium battery is less than or equal to the ternary equilibrium target critical value, or the minimum single-cell SOC + critical value when the internal inconsistency of the ternary lithium battery is greater than the equilibrium target critical value; the lithium iron phosphate internal equilibrium target SOC is the maximum single-cell SOC when the internal inconsistency of the lithium iron phosphate battery is less than or equal to the lithium iron phosphate equilibrium target critical value, or the minimum single-cell SOC + critical value when the internal inconsistency of the ternary lithium battery is greater than the lithium iron phosphate equilibrium target critical value;

[0030] The battery capacity gap of the ternary lithium battery after internal equilibrium according to the ternary internal equilibrium target SOC of the ternary lithium battery, and the internal equilibrium of the lithium iron phosphate battery according to the lithium iron phosphate internal equilibrium target SOC of the lithium iron phosphate battery include:

[0031] Ternary single-cell batteries with SOC greater than the corresponding ternary internal equilibrium target SOC are all internally balanced for an equilibrium duration corresponding to an equilibrium amount of [(SOC - ternary internal equilibrium target SOC) * SOH1 * C1];

[0032] Lithium iron phosphate single-cell batteries with SOC greater than the corresponding lithium iron phosphate internal equilibrium target SOC are all internally balanced for an equilibrium duration corresponding to an equilibrium amount of [(SOC - lithium iron phosphate internal equilibrium target SOC) * SOH2 * C2];

[0033] Wherein, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C.

[0034] Further, if the battery capacity gap of the ternary lithium battery is greater than the battery capacity gap of the lithium iron phosphate battery, then calculate the lithium iron phosphate comprehensive equilibrium target SOC = the lithium iron phosphate internal equilibrium target SOC of the lithium iron phosphate battery - (Q3 - Q4) / (SOH2 * C2), and then all lithium iron phosphate single-cell batteries with SOC higher than the lithium iron phosphate comprehensive equilibrium target SOC are comprehensively balanced for an equilibrium duration corresponding to an equilibrium capacity of [(SOC - lithium iron phosphate comprehensive equilibrium target SOC) * (SOH2 * C2)], and the equilibrium duration of lithium iron phosphate single-cell batteries with SOC lower than the lithium iron phosphate comprehensive equilibrium target SOC is set to 0;

[0035] Ternary single-cell batteries with SOC higher than the ternary internal equilibrium target SOC are internally balanced according to the ternary internal equilibrium target SOC, and the equilibrium duration of ternary single-cell batteries with SOC lower than the ternary internal equilibrium target SOC is set to 0;

[0036] Among them, Q3 is the battery capacity difference of the ternary lithium battery, Q3 = (a% - ternary internal balance target SOC) * SOH1 * C1, Q4 is the battery capacity difference of the lithium iron phosphate battery, Q4 = (a% - lithium iron internal balance target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25°C, and a% is the external balance target SOC of the ternary lithium battery.

[0037] Further, if the battery capacity difference of the ternary lithium battery is less than the battery capacity difference of the lithium iron phosphate battery, then calculate the ternary comprehensive balance target SOC = the ternary internal balance target SOC of the ternary lithium battery - (Q4 - Q3) / (SOH1 * C1), and then perform comprehensive balancing on the ternary single cells with SOC higher than the ternary comprehensive balance target SOC for the corresponding balancing duration with the balancing amount of [(SOC - ternary comprehensive balance target SOC) * (SOH1 * C1)], and set the balancing duration of the ternary single cells with SOC lower than the ternary comprehensive balance target SOC to 0;

[0038] Perform internal balancing on the lithium iron phosphate single cells with SOC higher than the lithium iron internal balance target SOC according to the lithium iron phosphate internal balance target SOC, and set the balancing duration of the lithium iron phosphate single cells with SOC lower than the lithium iron internal balance target SOC to 0;

[0039] Among them, Q3 is the battery capacity difference of the ternary lithium battery, Q3 = (a% - ternary internal balance target SOC) * SOH1 * C1, Q4 is the battery capacity difference of the lithium iron phosphate battery, Q4 = (a% - lithium iron internal balance target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25°C.

[0040] Further, if the ternary lithium batteries all meet the OCV correction condition and the lithium iron phosphate batteries do not meet the OCV correction condition, then determine the balancing methods for the single cells of different types and the corresponding balancing durations, including:

[0041] If the ternary lithium battery is performing comprehensive balancing according to the historical balancing duration, then both the ternary lithium battery and the lithium iron phosphate battery continue to balance according to their respective historical balancing durations;

[0042] If the ternary lithium battery is not comprehensively balanced, the updated balancing duration of the ternary lithium battery is determined according to the internal balancing target SOC of the ternary, and the lithium iron phosphate batteries continue to be balanced according to their respective historical balancing durations.

[0043] Further, determining whether all the single cells satisfy the OCV correction condition according to the SOC of the single cell includes:

[0044] Interpolate the SOC using the voltage of the single cell as the OCV to obtain the relationship curve between the single cell and the SOC, so as to obtain the SOC of each single cell.

[0045] If all the lithium iron single cells of the lithium iron phosphate battery are in the "non-platform period" of the relationship curve, or some of the lithium iron single cells are in the "non-platform period", it is determined that all the single cells satisfy the OCV correction condition.

[0046] If all the lithium iron single cells of the lithium iron phosphate battery are in the "platform period" of the relationship curve, it is determined that the ternary lithium battery satisfies the OCV correction condition, and the lithium iron phosphate battery does not satisfy the OCV correction condition.

[0047] In a second aspect, there is provided a balancing device for a battery parallel-series system, the battery parallel-series system including a ternary lithium battery and a lithium iron phosphate battery, the device including:

[0048] An acquisition module for acquiring the SOC state of the single cells in the battery parallel-series system;

[0049] A determination module for determining the balancing method of the single cell and the corresponding balancing target SOC according to the SOC of the single cell;

[0050] A control module for determining the balancing capacity of the single cell according to the balancing target SOC and calculating the balancing duration according to the balancing capacity, so as to realize the balancing control of the single cell.

[0051] In a third aspect, there is provided a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the balancing method of the battery parallel-series system as described above is implemented.

[0052] In a fourth aspect, there is provided an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the balancing method of the battery parallel-series system as described above is implemented.

[0053] The present invention has the following beneficial effects:

[0054] 1. To address the issue of inconsistency between two types of single cells, namely ternary lithium batteries and lithium iron phosphate batteries, as well as among the same type of single cells, internal balancing of the same type of battery and external balancing of different types of batteries are achieved.

[0055] 2. Taking the OCV correction conditions and the judgment of whether the charge and discharge cut-off voltages are reached as the starting points, the balancing method and the balancing duration are updated in real time to ensure the safe driving of the vehicle while extending the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0057] Figure 1 It is a flowchart of the balancing method for the battery parallel-series system in the embodiments of the present invention;

[0058] Figure 2 It is a judgment logic diagram of the balancing method for the battery parallel-series system in the embodiments of the present invention:

[0059] Figure 3 It is a schematic diagram of the balancing device for the battery parallel-series system in the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0060] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0061] Throughout the specification, the reference to "one embodiment", "one example" or "example" means that the specific features, structures or characteristics described in connection with that embodiment or example are included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment", "in an embodiment", "one example" or "example" that appear throughout the specification do not necessarily all refer to the same embodiment or example. In addition, the specific features, structures or characteristics can be combined in any suitable combination and / or sub-combination in one or more embodiments or examples.

[0062] The following will elaborate in detail on the balancing method, device, storage medium and electronic device of the battery parallel-series system in the present invention in conjunction with the drawings and specific embodiments.

[0063] Embodiment 1

[0064] As Figure 1 shown, this embodiment provides an equalization method for a battery parallel - series system. The battery parallel - series system includes a ternary lithium battery and a lithium iron phosphate battery. The method includes:

[0065] S101. Obtain the SOC state of the single cells in the battery parallel - series system;

[0066] S102. Determine the equalization method for the single cells and the corresponding equalization target SOC according to the SOC of the single cells;

[0067] S103. Determine the equalization capacity of the single cells according to the equalization target SOC, and calculate the equalization duration according to the equalization capacity, so as to realize the equalization control of the single cells.

[0068] In this embodiment, SOC is numerically defined as the ratio of the remaining capacity to the battery capacity, usually expressed as a percentage, and its value range is 0 - 1. When SOC = 0, it means the battery is completely discharged, and when SOC = 1, it means the battery is fully charged. The SOC state of the single cells includes whether the cut - off voltage is reached and whether the OCV (Open Circuit Voltage, the potential difference between the two poles when the battery is open - circuited without discharging) correction condition is satisfied.

[0069] Equalization control means opening the equalization implementation channels of all single cells that need to be equalized, and ensuring that the channels are in the open state during the power - on process until the equalization duration is met.

[0070] The equalization methods include internal equalization, external equalization, and comprehensive equalization. Among them, equalization refers to the discharging process of the single cells. Internal equalization means that a single cell discharges to the same type of single cells, external equalization means that a single cell discharges to different types of single cells, and comprehensive equalization means that a single cell discharges to the same type of single cells and also discharges to different types of single cells at the same time.

[0071] The equalization target refers to the external equalization of aligning the maximum single - cell SOC of the ternary lithium battery to a% (a ≤ 100) with the maximum single - cell SOC of the lithium iron phosphate battery being 100%, and the internal equalization of the inconsistency between single cells of the ternary lithium battery ≤ m% and the inconsistency between single cells of the lithium iron phosphate battery ≤ n%. Among them, the maximum single - cell SOC of the lithium iron phosphate battery being 100% in the external equalization target is to ensure that the lithium iron phosphate battery can be fully charged. Single cells that need to perform external equalization and internal equalization simultaneously can perform comprehensive equalization.

[0072] In this embodiment, the balanced target SOC includes the external balanced target SOC, the internal balanced target SOC, and the comprehensive balanced target OSC. Among them, the external balanced target means that the SOC of the ternary lithium battery and the SOC of the lithium iron phosphate battery satisfy a certain corresponding relationship. Exemplarily, the maximum SOC of the ternary monomer battery is a% (a ≤ 100), which is aligned with the external balance where the maximum SOC of the lithium iron phosphate monomer battery is 100%. Among them, the maximum SOC of the lithium iron phosphate in the external balanced target SOC is 100% to ensure that the lithium iron phosphate battery can be fully charged. The internal balanced target SOC refers to the maximum SOC of the same type of monomer battery when the internal inconsistency is less than or equal to the corresponding balanced target critical value (m% for ternary and n% for lithium iron phosphate), or the minimum SOC + critical value of the same type of monomer battery when the internal inconsistency is greater than the balanced target critical value. The comprehensive balance benchmark means that assuming that the ternary monomer battery and the lithium iron phosphate monomer battery are charged at the same current with their respective internal balanced target SOCs until they reach a% of the ternary and 100% of the lithium iron phosphate and then stop. The one that reaches first needs to perform external balance, and the SOC corresponding to subtracting the difference in battery capacity between the two from the capacity corresponding to the internal balanced target SOC of the one that reaches first is the comprehensive balanced target SOC. Exemplarily, the comprehensive balanced target SOC of lithium iron phosphate = the internal balanced target SOC of lithium iron phosphate of the lithium iron phosphate battery - (Q3 - Q4) / (SOH2 * C2), and the comprehensive balanced target SOC of ternary = the internal balanced target SOC of ternary of the ternary lithium battery - (Q4 - Q3) / (SOH1 * C1), where Q3 is the battery capacity difference of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25°C, and a% is the external balanced target SOC of the ternary lithium battery. By comparing the battery capacity differences of the two batteries, the comprehensive balanced target of the party that needs to perform external balance can be determined, and thus the balanced duration can be calculated.

[0073] The balanced capacity described in this embodiment, that is, the capacity that needs to be balanced, refers to the corresponding capacity between the SOC of the monomer battery that needs to be balanced and the balanced target SOC. The balanced duration refers to the total duration from the start of balance to reaching the balanced target during the power-on process, that is, the balanced capacity divided by the balanced current.

[0074] In this embodiment, the SOC state of the single cells in the battery hybrid system is obtained; the equalization method for the single cells and the corresponding equalization target SOC are determined according to the SOC of the single cells; the equalization capacity of the single cells is determined according to the equalization target SOC, and the equalization duration is calculated based on the equalization capacity. Based on the inconsistency problems between the ternary and lithium iron phosphate single cells and between the same type of single cells, the internal equalization of the same type of battery and the external equalization of different types of batteries are realized, so as to realize the equalization control of the single cells. Under the condition of ensuring the normal travel of the hybrid electric vehicle, the battery hybrid system is reasonably equalized and managed, ensuring the safe driving of the vehicle while extending the service life of the battery.

[0075] Further, if the SOC state of the single cell reaches the cut-off voltage, determining the equalization method for the single cell and the corresponding equalization target SOC according to the SOC of the single cell includes:

[0076] Determine the target battery type for which the equalization duration needs to be updated according to the type of the cut-off voltage and the type of the battery cell that reaches the cut-off voltage;

[0077] Determine the equalization capacity according to the external equalization target SOC of the target battery type.

[0078] In this embodiment, the types of the cut-off voltage include the charging cut-off voltage and the discharge medium voltage. Corresponding to different types of cut-off voltages and different types of battery cells that reach the cut-off voltage, the determined equalization capacities are different.

[0079] Further, the method further includes:

[0080] For other types of batteries except the target battery type, equalize according to the historical equalization duration.

[0081] Further, if the type of the cut-off voltage is the charging cut-off voltage and the type of the battery cell that reaches the cut-off voltage is the ternary lithium battery, clear the historical equalization duration of all ternary single cells;

[0082] All ternary single cells perform external equalization with the equalization duration corresponding to the equalization capacity of [(1 - a%) * SOH1 * C1], where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, and C1 is the battery capacity of the ternary lithium battery at 25°C.

[0083] In this embodiment, the type of battery cell that reaches the cut-off voltage is a ternary lithium battery, indicating that the ternary lithium battery is first fully charged. Therefore, the external equalization target SOC of the ternary lithium battery is set to a%. Before equalizing the ternary battery cells, first clear the historical equalization duration of the ternary battery cells, retain the historical equalization duration of the lithium iron phosphate battery cells, and the lithium iron phosphate battery cells continue to be equalized according to the historical equalization duration.

[0084] Further, if the type of cut-off voltage is the charging cut-off voltage and the type of battery cell that reaches the cut-off voltage is the lithium iron phosphate battery, then all the lithium iron phosphate battery cells continue to be equalized according to the corresponding historical equalization duration.

[0085] In this embodiment, if the type of cut-off voltage is the charging cut-off voltage and the type of battery cell that reaches the cut-off voltage is the lithium iron phosphate battery, it means that the lithium iron phosphate battery cells are already fully charged, and the external equalization target SOC of the lithium iron phosphate battery cells is 100%. Therefore, continue to equalize according to the corresponding historical equalization duration.

[0086] Further, if the type of cut-off voltage is the discharging cut-off voltage, let Q1 = a% * SOH1 * C1, Q2 = 100% * SOH1 * C1, where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C;

[0087] If Q1 > Q2 and the type of battery cell that reaches the cut-off voltage is the ternary lithium battery, then determine that the target battery type is the lithium iron phosphate battery, and all the lithium iron phosphate battery cells perform external equalization with the equalization duration corresponding to Q1 - Q2;

[0088] If Q1 > Q2 and the type of battery cell that reaches the cut-off voltage is the lithium phosphate battery, then there is no target battery type, and all the lithium iron phosphate battery cells are equalized according to the historical equalization duration.

[0089] In this embodiment, if Q1 > Q2 and the type of battery cell that reaches the cut-off voltage is the ternary lithium battery, it means that the lithium iron phosphate battery needs to be discharged, and the equalization duration of the lithium iron phosphate battery cells needs to be updated. If Q1 > Q2 and the type of battery cell that reaches the cut-off voltage is the lithium phosphate battery, then the equalization duration of the lithium iron phosphate battery cells does not need to be updated.

[0090] Further, the method further includes:

[0091] If Q1 < Q2 and the type of battery cell that reaches the cut-off voltage is a ternary lithium battery, then there is no target battery type, and all ternary battery cells are equalized according to the historical equalization duration.

[0092] If Q1 < Q2 and the type of battery cell that reaches the cut-off voltage is a lithium iron phosphate battery, the target battery type is a ternary lithium battery, and all ternary battery cells are externally equalized with the equalization duration corresponding to Q1 - Q2 as the equalization capacity.

[0093] In this embodiment, if Q1 < Q2 and the type of battery cell that reaches the cut-off voltage is a ternary lithium battery, then it is not necessary to update the equalization duration of the ternary battery cells. If Q1 < Q2 and the type of battery cell that reaches the cut-off voltage is a lithium iron phosphate battery, then it is necessary to update the equalization duration of the ternary lithium battery.

[0094] Further, the method further includes:

[0095] If the static duration of the battery parallel-series system is greater than or equal to T and the current after static is less than i, determining the equalization method of the battery cells according to the SOC of the battery cells and the equalization target SOC corresponding to the equalization method includes:

[0096] Judging whether all battery cells satisfy the OCV correction condition according to the SOC of the battery cells, and on this basis, determining the equalization method of different types of battery cells and the equalization duration corresponding to the equalization method.

[0097] Further, if all battery cells satisfy the OCV correction condition, determining the equalization method of different types of battery cells and the equalization duration corresponding to the equalization method includes:

[0098] Calculating the battery capacity difference of the ternary lithium battery after internal equalization of the ternary lithium battery according to the ternary internal equalization target SOC of the ternary lithium battery, and the battery capacity difference of the lithium iron phosphate battery after internal equalization of the lithium iron phosphate battery according to the lithium iron internal equalization target SOC of the lithium iron phosphate battery;

[0099] Determining the equalization method of the ternary lithium battery and the lithium iron phosphate battery according to the magnitude relationship between the battery capacity difference of the ternary lithium battery and the battery capacity difference of the lithium iron phosphate battery.

[0100] Further, the ternary internal equilibrium target SOC is the maximum single-cell SOC when the internal inconsistency of the ternary lithium battery is less than or equal to the ternary equilibrium target critical value, or the minimum single-cell SOC + critical value when the internal inconsistency of the ternary lithium battery is greater than the equilibrium target critical value; the lithium iron phosphate internal equilibrium target SOC is the maximum single-cell SOC when the internal inconsistency of the lithium iron phosphate battery is less than or equal to the lithium iron phosphate equilibrium target critical value, or the minimum single-cell SOC + critical value when the internal inconsistency of the ternary lithium battery is greater than the lithium iron phosphate equilibrium target critical value;

[0101] The battery capacity gap of the ternary lithium battery after internal equilibrium according to the ternary internal equilibrium target SOC of the ternary lithium battery, and the internal equilibrium of the lithium iron phosphate battery according to the lithium iron phosphate internal equilibrium target SOC of the lithium iron phosphate battery include:

[0102] All ternary single cells with SOC greater than the corresponding ternary internal equilibrium target SOC are internally balanced for an equilibrium duration corresponding to an equilibrium capacity of [(SOC - ternary internal equilibrium target SOC) * SOH1 * C1];

[0103] All lithium iron phosphate single cells with SOC greater than the corresponding lithium iron phosphate internal equilibrium target SOC are internally balanced for an equilibrium duration corresponding to an equilibrium capacity of [(SOC - lithium iron phosphate internal equilibrium target SOC) * SOH2 * C2];

[0104] Wherein, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C.

[0105] In this embodiment, during internal equilibrium, ternary single cells with SOC greater than the corresponding ternary internal equilibrium target SOC are internally balanced, while ternary single cells with SOC less than the corresponding ternary internal equilibrium target SOC are not internally balanced. Similarly, lithium iron phosphate single cells with SOC greater than the corresponding lithium iron phosphate internal equilibrium target SOC are internally balanced, while lithium iron phosphate single cells with SOC less than the corresponding lithium iron phosphate internal equilibrium target SOC are not internally balanced.

[0106] Further, if the battery capacity gap of the ternary lithium battery is greater than the battery capacity gap of the lithium iron phosphate battery, then calculate the lithium iron phosphate comprehensive equilibrium target SOC = lithium iron phosphate internal equilibrium target SOC of the lithium iron phosphate battery - (Q3 - Q4) / (SOH2 * C2), and all lithium iron phosphate single cells with SOC higher than the lithium iron phosphate comprehensive equilibrium target SOC are comprehensively balanced for an equilibrium duration corresponding to an equilibrium capacity of [(SOC - lithium iron phosphate comprehensive equilibrium target SOC) * (SOH2 * C2)], and the equilibrium duration of lithium iron phosphate single cells with SOC lower than the lithium iron phosphate comprehensive equilibrium target SOC is set to 0;

[0107] For ternary single cells with an SOC higher than the ternary internal equilibrium target SOC, perform internal equilibrium according to the ternary internal equilibrium target SOC, and set the equilibrium duration of ternary single cells with an SOC lower than the ternary internal equilibrium target SOC to 0;

[0108] Among them, Q3 is the battery capacity difference of the ternary lithium battery, Q3 = (a% - ternary internal equilibrium target SOC) * SOH1 * C1, Q4 is the battery capacity difference of the lithium iron phosphate battery, Q4 = (a% - lithium iron internal equilibrium target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25 °C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25 °C, and a% is the external equilibrium target SOC of the ternary lithium battery.

[0109] In this embodiment, the battery capacity difference of the ternary lithium battery refers to the capacity difference corresponding to the difference between the external equilibrium target SOC and the ternary internal equilibrium target SOC, and the battery capacity difference of the lithium iron phosphate battery refers to the capacity difference corresponding to the difference between the external equilibrium target SOC and the lithium iron internal equilibrium target SOC. If Q3 > Q4, it means that the lithium iron phosphate battery needs to perform external equilibrium. Therefore, it is necessary to first determine the lithium iron comprehensive equilibrium target SOC. For lithium iron single cells with an SOC higher than the lithium iron comprehensive equilibrium target SOC, perform comprehensive equilibrium. It should be emphasized here that comprehensive equilibrium includes internal and external equilibrium. Therefore, for these lithium iron single cells, after clearing the historical equilibrium duration, only comprehensive equilibrium is required, and no further internal equilibrium is needed. For lithium iron single cells with an SOC lower than the lithium iron comprehensive equilibrium target SOC, no equilibrium is required.

[0110] For the ternary lithium battery, perform internal equilibrium on ternary single cells with an SOC higher than the ternary internal equilibrium target SOC. Specifically, perform internal equilibrium with the equilibrium duration corresponding to [(SOC - ternary internal equilibrium target SOC) * SOH1 * C1]. For ternary single cells with an SOC lower than the ternary internal equilibrium target SOC, no equilibrium is required.

[0111] Further, if the battery capacity difference of the ternary lithium battery is less than that of the lithium iron phosphate battery, calculate the ternary comprehensive equilibrium target SOC = the ternary internal equilibrium target SOC of the ternary lithium battery - (Q4 - Q3) / (SOH1 * C1). Then, for all ternary single cells in the ternary lithium battery with SOC higher than the ternary comprehensive equilibrium target SOC, perform comprehensive equilibrium with the equilibrium duration corresponding to the equilibrium amount of [(SOC - ternary comprehensive equilibrium target SOC) * (SOH1 * C1)]. For all ternary single cells in the ternary lithium battery with SOC lower than the ternary comprehensive equilibrium target SOC, set the equilibrium duration to 0;

[0112] Perform internal equilibrium according to the lithium iron phosphate internal equilibrium target SOC for all lithium iron phosphate single cells in all lithium iron phosphate batteries with SOC higher than the lithium iron phosphate internal equilibrium target SOC, and set the equilibrium duration of all lithium iron phosphate single cells in all lithium iron phosphate batteries with SOC lower than the lithium iron phosphate internal equilibrium target SOC to 0;

[0113] Among them, Q3 is the battery capacity difference of the ternary lithium battery, Q3 = (a% - ternary internal equilibrium target SOC) * SOH1 * C1, Q4 is the battery capacity difference of the lithium iron phosphate battery, Q4 = (a% - lithium iron phosphate internal equilibrium target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C.

[0114] In this embodiment, if Q3 < Q4, it indicates that the ternary lithium battery needs external equilibrium. Therefore, it is necessary to first determine the ternary comprehensive equilibrium target SOC. For the ternary single cells with SOC higher than the ternary comprehensive equilibrium target SOC, perform comprehensive equilibrium. It should be emphasized here that comprehensive equilibrium includes both internal and external equilibrium. Therefore, for these ternary single cells, after clearing the historical equilibrium duration, only comprehensive equilibrium is required, and no further internal equilibrium is needed. For ternary single cells with SOC lower than the ternary comprehensive equilibrium target SOC, no equilibrium is required.

[0115] For the lithium iron phosphate battery, perform internal equilibrium on the lithium iron phosphate single cells with SOC higher than the lithium iron phosphate internal equilibrium target SOC. Specifically, perform internal equilibrium with the equilibrium duration corresponding to [(SOC - lithium iron phosphate internal equilibrium target SOC) * SOH1 * C1]. For lithium iron phosphate single cells with SOC lower than the lithium iron phosphate internal equilibrium target SOC, no equilibrium is required.

[0116] Further, if the ternary lithium battery all meets the OCV correction conditions and the lithium iron phosphate battery does not meet the OCV correction conditions, determine the equilibrium methods for different types of single cells and the equilibrium durations corresponding to the equilibrium methods, including:

[0117] If the ternary lithium battery is undergoing comprehensive equalization according to the historical equalization duration, both the ternary lithium battery and the lithium iron phosphate battery continue to equalize according to their respective historical equalization durations;

[0118] If the ternary lithium battery does not undergo comprehensive equalization, the updated equalization duration of the ternary lithium battery is determined according to the internal equalization target SOC of the ternary battery, and the lithium iron phosphate batteries continue to equalize according to their respective historical equalization durations.

[0119] In this embodiment, the updated equalization duration of the ternary lithium battery is the equalization duration corresponding to [(SOC - internal equalization target SOC of the ternary battery) * SOH1 * C1].

[0120] Further, determining whether all single cells meet the OCV correction condition according to the SOC of the single cell includes:

[0121] Using the voltage of the single cell as the OCV for SOC interpolation to obtain the relationship curve between the voltage of the single cell and the SOC, so as to obtain the SOC of each single cell;

[0122] If all the lithium iron single cells of the lithium iron phosphate battery are in the "non - plateau period" of the relationship curve, or some of the lithium iron single cells are in the "non - plateau period", it is determined that all single cells meet the OCV correction condition;

[0123] If all the lithium iron single cells of the lithium iron phosphate battery are in the "plateau period" of the relationship curve, it is determined that the ternary lithium battery meets the OCV correction condition, and the lithium iron phosphate battery does not meet the OCV correction condition.

[0124] In this embodiment, the relationship curve of the ternary lithium battery is relatively steep, similar to y = cx + d, and the relationship curve of the lithium iron phosphate battery has a plateau period and a non - plateau period. In the plateau period, the relationship curve is similar to y = e, and in the non - plateau period, the relationship curve is similar to y = cx + d. Therefore, if all the lithium iron single cells of the lithium iron phosphate battery are in the "non - plateau period" of the relationship curve, or some of the lithium iron single cells are in the "non - plateau period", it is determined that all single cells meet the OCV correction condition, and the single cells in the "plateau period" are processed according to the SOC corresponding to the boundary of the "plateau period".

[0125] In this embodiment, taking the OCV correction point and the judgment of whether the charge - discharge cut - off voltage is reached as the entry point, the equalization strategy is updated in real time to ensure the safe driving of the vehicle while extending the service life of the battery.

[0126] As Figure 2 shown, it is the judgment logic diagram of the equalization method for the battery parallel - series system in this embodiment:

[0127] S21. After power-on, determine whether the voltage of a single cell reaches the cut-off voltage;

[0128] S22. When the voltage of a single cell reaches the cut-off voltage, determine whether there is a single cell that needs external equalization;

[0129] S221. When there is a single cell that needs external equalization, update the equalization duration of the single cell that needs external equalization, and the others inherit the historical equalization duration;

[0130] S222. When there is no single cell that needs external equalization, determine whether to power off;

[0131] S23. When no single cell voltage reaches the cut-off voltage, determine whether all single cells meet the OCV correction conditions;

[0132] S231. When all single cells meet the OCV correction conditions, clear the historical equalization duration of the single cells that need equalization, and perform comprehensive equalization or internal equalization;

[0133] S232. When not all single cells meet the OCV correction conditions, determine whether only ternary lithium batteries meet the OCV correction conditions;

[0134] S2321. If only ternary lithium batteries meet the OCV correction conditions, determine whether the ternary lithium batteries are performing comprehensive equalization;

[0135] S23211. If so, both the ternary lithium batteries and the lithium iron phosphate batteries continue to equalize according to the historical equalization duration;

[0136] S23212. If not, clear the equalization duration of the ternary lithium batteries, and perform internal equalization on the ternary lithium batteries, and the lithium iron phosphate batteries inherit the historical equalization duration;

[0137] S2322. If not only ternary lithium batteries meet the OCV correction conditions, determine whether to power off;

[0138] S24. After power-off, save the remaining equalization duration.

[0139] Embodiment 2

[0140] As Figure 3 shown, this embodiment provides an equalization device for a battery parallel-series system. The battery parallel-series system includes ternary lithium batteries and lithium iron phosphate batteries. The device includes:

[0141] An acquisition module 301, configured to acquire the SOC state of the single cells in the battery parallel-series system;

[0142] A determination module 302, configured to determine an equalization method for a single battery and an equalization target SOC corresponding to the equalization method according to the SOC of the single battery;

[0143] A control module 303, configured to determine an equalization capacity of the single battery according to the equalization target SOC, and calculate an equalization duration according to the equalization capacity, so as to implement equalization control of the single battery.

[0144] Further, the determination module 302 is further configured to:

[0145] Determine a target battery type for which the equalization duration needs to be updated according to the type of cut-off voltage and the type of battery cell that reaches the cut-off voltage;

[0146] Determine an equalization capacity according to the external equalization target SOC of the target battery type.

[0147] Further, the determination module 302 is further configured to:

[0148] For battery types other than the target battery type, perform equalization according to the historical equalization duration.

[0149] Further, if the type of cut-off voltage is a charging cut-off voltage and the type of battery cell that reaches the cut-off voltage is a ternary lithium battery, the control module 303 is further configured to: clear the historical equalization duration of all ternary single battery cells;

[0150] All ternary single battery cells perform external equalization with an equalization duration corresponding to an equalization capacity of [(1 - a%) * SOH1 * C1], where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, and C1 is the battery capacity of the ternary lithium battery at 25°C.

[0151] Further, if the type of cut-off voltage is a charging cut-off voltage and the type of battery cell that reaches the cut-off voltage is a lithium iron phosphate battery, the control module 303 is further configured to: continue to perform equalization on all lithium iron phosphate single battery cells according to the corresponding historical equalization duration.

[0152] Further, if the type of cut-off voltage is a discharging cut-off voltage, let Q1 = a% * SOH1 * C1, Q2 = 100% * SOH1 * C1, where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C;

[0153] If Q1 > Q2, and the type of the battery cell that reaches the cut-off voltage is a ternary lithium battery, the control module 303 is further configured to: determine that the target battery type is a lithium iron phosphate battery, and all lithium iron monomer batteries perform external balancing with the balancing duration corresponding to the balancing capacity of Q1 - Q2;

[0154] If Q1 > Q2, and the type of the battery cell that reaches the cut-off voltage is a lithium phosphate battery, the control module 303 is further configured to: there is no target battery type, and all lithium iron monomer batteries perform balancing according to the historical balancing duration.

[0155] Further, the method further includes:

[0156] If Q1 < Q2, and the type of the battery cell that reaches the cut-off voltage is a ternary lithium battery, the control module 303 is further configured to: there is no target battery type, and all ternary monomer batteries perform balancing according to the historical balancing duration;

[0157] If Q1 < Q2, and the type of the battery cell that reaches the cut-off voltage is a lithium phosphate battery, the control module 303 is further configured to: determine that the target battery type is a ternary lithium battery, and all ternary monomer batteries perform external balancing with the balancing duration corresponding to the balancing capacity of Q1 - Q2.

[0158] Further, the method further includes:

[0159] If the static duration of the battery parallel-series system is greater than or equal to T, and the current after static is less than i, the determination module 302 is further configured to:

[0160] Judge whether all monomer batteries meet the OCV correction condition according to the SOC of the monomer battery, and on this basis, determine the balancing method for different types of monomer batteries and the balancing duration corresponding to the balancing method.

[0161] Further, the control module 303 is further configured to:

[0162] Calculate the battery capacity difference of the ternary lithium battery after internal balancing of the ternary lithium battery according to the ternary internal balancing target SOC of the ternary lithium battery, and the battery capacity difference of the lithium iron phosphate battery after internal balancing of the lithium iron phosphate battery according to the lithium iron internal balancing target SOC of the lithium iron phosphate battery;

[0163] Determine the balancing method for the ternary lithium battery and the lithium iron phosphate battery according to the magnitude relationship between the battery capacity difference of the ternary lithium battery and the battery capacity difference of the lithium iron phosphate battery.

[0164] Further, the ternary internal equilibrium target SOC is the maximum single-cell SOC when the internal inconsistency of the ternary lithium battery is less than or equal to the ternary equilibrium target critical value, or the minimum single-cell SOC + the critical value when the internal inconsistency of the ternary lithium battery is greater than the equilibrium target critical value; the lithium iron phosphate internal equilibrium target SOC is the maximum single-cell SOC when the internal inconsistency of the lithium iron phosphate battery is less than or equal to the lithium iron phosphate equilibrium target critical value, or the minimum single-cell SOC + the critical value when the internal inconsistency of the ternary lithium battery is greater than the lithium iron phosphate equilibrium target critical value;

[0165] The control module 303 is further configured to:

[0166] Perform internal equilibrium on the ternary single-cell batteries with SOC greater than the corresponding ternary internal equilibrium target SOC for an equilibrium duration corresponding to the equilibrium amount of [(SOC - ternary internal equilibrium target SOC) * SOH1 * C1];

[0167] Perform internal equilibrium on the lithium iron phosphate single-cell batteries with SOC greater than the corresponding lithium iron phosphate internal equilibrium target SOC for an equilibrium duration corresponding to the equilibrium amount of [(SOC - lithium iron phosphate internal equilibrium target SOC) * SOH2 * C2];

[0168] Wherein, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C.

[0169] Further, if the battery capacity gap of the ternary lithium battery is greater than the battery capacity gap of the lithium iron phosphate battery, the control module 303 is further configured to: calculate the lithium iron phosphate comprehensive equilibrium target SOC = the lithium iron phosphate internal equilibrium target SOC of the lithium iron phosphate battery - (Q3 - Q4) / (SOH2 * C2), perform comprehensive equilibrium on the lithium iron phosphate single-cell batteries with SOC higher than the lithium iron phosphate comprehensive equilibrium target SOC for an equilibrium duration corresponding to the equilibrium capacity of [(SOC - lithium iron phosphate comprehensive equilibrium target SOC) * (SOH2 * C2)], and set the equilibrium duration of the lithium iron phosphate single-cell batteries with SOC lower than the lithium iron phosphate comprehensive equilibrium target SOC to 0;

[0170] Perform internal equilibrium on the ternary single-cell batteries with SOC higher than the ternary internal equilibrium target SOC according to the ternary internal equilibrium target SOC, and set the equilibrium duration of the ternary single-cell batteries with SOC lower than the ternary internal equilibrium target SOC to 0;

[0171] Among them, Q3 is the battery capacity gap of the ternary lithium battery, Q3 = (a% - ternary internal balance target SOC) * SOH1 * C1, Q4 is the battery capacity gap of the lithium iron phosphate battery, Q4 = (a% - lithium iron internal balance target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25 °C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25 °C, and a% is the external balance target SOC of the ternary lithium battery.

[0172] Further, if the battery capacity gap of the ternary lithium battery is less than that of the lithium iron phosphate battery, the control module 303 is further configured to: calculate the ternary comprehensive balance target SOC = ternary internal balance target SOC of the ternary lithium battery - (Q4 - Q3) / (SOH1 * C1), and perform comprehensive balancing on the ternary single cells with SOC higher than the ternary comprehensive balance target SOC for a balance duration corresponding to the balance amount of [(SOC - ternary comprehensive balance target SOC) * (SOH1 * C1)], and set the balance duration of the ternary single cells with SOC lower than the ternary comprehensive balance target SOC to 0;

[0173] Perform internal balancing on the lithium iron phosphate single cells with SOC higher than the lithium iron internal balance target SOC according to the lithium iron phosphate internal balance target SOC, and set the balance duration of the lithium iron phosphate single cells with SOC lower than the lithium iron internal balance target SOC to 0;

[0174] Among them, Q3 is the battery capacity gap of the ternary lithium battery, Q3 = (a% - ternary internal balance target SOC) * SOH1 * C1, Q4 is the battery capacity gap of the lithium iron phosphate battery, Q4 = (a% - lithium iron internal balance target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25 °C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25 °C.

[0175] Further, the control module 303 is further configured to:

[0176] If the ternary lithium battery is performing comprehensive balancing according to the historical balance duration, both the ternary lithium battery and the lithium iron phosphate battery continue to balance according to their respective historical balance durations;

[0177] If the ternary lithium battery does not perform comprehensive balancing, determine the updated balance duration of the ternary lithium battery according to the ternary internal balance target SOC, and continue to balance the lithium iron phosphate batteries according to their respective historical balance durations.

[0178] Further, the control module 303 is further configured to:

[0179] Interpolate the SOC using the voltage of the single cell as the OCV to obtain the relationship curve between the single cell and the SOC, so that the SOC of each single cell can be obtained;

[0180] If all the lithium iron phosphate single cells of the lithium iron phosphate battery are in the "non-platform period" of the relationship curve, or some of the lithium iron phosphate single cells are in the "non-platform period", it is determined that all single cells meet the OCV correction conditions;

[0181] If all the lithium iron phosphate single cells of the lithium iron phosphate battery are in the "platform period" of the relationship curve, it is determined that the ternary lithium battery meets the OCV correction conditions, and the lithium iron phosphate battery does not meet the OCV correction conditions.

[0182] Embodiment III

[0183] This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the balancing method as in Embodiment I.

[0184] Embodiment IV

[0185] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, it implements the balancing method as in Embodiment I.

[0186] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative labor.

[0187] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, also by hardware. Based on this understanding, the above technical solutions, in essence, or the parts that contribute to the prior art can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An equalization method for a battery series-parallel system, the battery series-parallel system including a ternary lithium battery and a lithium iron phosphate battery, characterized in that, The equalization method includes: Obtaining the SOC state of the single cells in the battery parallel-series system; Determining the equalization method for the single cell and the corresponding equalization target SOC according to the SOC of the single cell; Determining the equalization capacity of the single cell according to the equalization target SOC, and calculating the equalization duration according to the equalization capacity, so as to realize the equalization control of the single cell; Wherein, if the SOC state of the single cell reaches the cut-off voltage, determining the equalization method for the single cell and the corresponding equalization target SOC according to the SOC of the single cell includes: Determining the target cell type for which the equalization duration needs to be updated according to the type of the cut-off voltage and the type of the cell single body that reaches the cut-off voltage; Determining the equalization capacity according to the external equalization target SOC of the target cell type; If the type of the cut-off voltage is the charging cut-off voltage and the type of the cell single body that reaches the cut-off voltage is a ternary lithium battery, clear the historical equalization duration of all ternary single cells; All the ternary single cells perform external equalization with the equalization duration corresponding to the equalization capacity of [(1 - a%) * SOH1 * C1], where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, and C1 is the battery capacity of the ternary lithium battery at 25°C; If the type of the cut-off voltage is the charging cut-off voltage and the type of the cell single body that reaches the cut-off voltage is a lithium iron phosphate battery, continue to equalize all the lithium iron single cells according to the corresponding historical equalization duration; If the type of the cut-off voltage is the discharging cut-off voltage, let Q1 = a% * SOH1 * C1, Q2 = 100% * SOH2 * C2, where a% is the external equalization target SOC of the ternary lithium battery, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, and C2 is the battery capacity of the lithium iron phosphate battery at 25°C; If Q1 > Q2 and the type of the cell single body that reaches the cut-off voltage is a ternary lithium battery, then determine that the target cell type is the lithium iron phosphate battery, and all the lithium iron single cells perform external equalization with the equalization duration corresponding to the equalization capacity of Q1 - Q2; If Q1 > Q2 and the type of the cell single body that reaches the cut-off voltage is the lithium iron phosphate battery, then there is no target cell type, and all the lithium iron single cells are equalized according to the historical equalization duration; If Q1 < Q2 and the type of the cell single body that reaches the cut-off voltage is a ternary lithium battery, then there is no target cell type, and all the ternary single cells are equalized according to the historical equalization duration; If Q1 < Q2 and the type of the cell single body that reaches the cut-off voltage is the lithium iron phosphate battery, the target cell type is the ternary lithium battery, and all the ternary single cells perform external equalization with the equalization duration corresponding to the equalization capacity of Q2 - Q1.

2. The equalization method according to claim 1, wherein If the static time of the battery parallel - series system is greater than or equal to T and the current after static is less than i, the method for determining the equalization of the single - cell battery according to the SOC of the single - cell battery and the equalization target SOC corresponding to the equalization method include: Judge whether all the single - cell batteries meet the OCV correction condition according to the SOC of the single - cell battery, and on this basis, determine the equalization methods for different types of the single - cell batteries and the equalization duration corresponding to the equalization method.

3. The equalization method according to claim 2, characterized in that, If all the single - cell batteries meet the OCV correction condition, determining the equalization methods for different types of the single - cell batteries and the equalization duration corresponding to the equalization method includes: Calculate the battery capacity difference of the ternary lithium battery after internal equalization according to the ternary internal equalization target SOC of the ternary lithium battery, and the battery capacity difference of the lithium iron phosphate battery after internal equalization according to the lithium iron internal equalization target SOC of the lithium iron phosphate battery; Determine the equalization methods for the ternary lithium battery and the lithium iron phosphate battery according to the magnitude relationship between the battery capacity difference of the ternary lithium battery and the battery capacity difference of the lithium iron phosphate battery; The ternary internal equalization target SOC is the maximum single - cell SOC when the internal inconsistency of the ternary lithium battery is less than or equal to the ternary equalization target critical value, or the minimum single - cell SOC + critical value when the internal inconsistency of the ternary lithium battery is greater than the equalization target critical value; the lithium iron internal equalization target SOC is the maximum single - cell SOC when the internal inconsistency of the lithium iron phosphate battery is less than or equal to the lithium iron equalization target critical value, or the minimum single - cell SOC + critical value when the internal inconsistency of the lithium iron phosphate battery is greater than the lithium iron equalization target critical value; The battery capacity difference of the ternary lithium battery after internal equalization according to the ternary internal equalization target SOC of the ternary lithium battery, and the internal equalization of the lithium iron phosphate battery according to the lithium iron internal equalization target SOC of the lithium iron phosphate battery include: Internal - equalize all ternary single - cell batteries with SOC greater than the corresponding ternary internal equalization target SOC for an equalization duration corresponding to an equalization amount of [(SOC - ternary internal equalization target SOC)*SOH1*C1]; Internal - equalize all lithium - iron single - cell batteries with SOC greater than the corresponding lithium - iron internal equalization target SOC for an equalization duration corresponding to an equalization amount of [(SOC - lithium - iron internal equalization target SOC)*SOH2*C2]; If the battery capacity difference of the ternary lithium battery is greater than the battery capacity difference of the lithium iron phosphate battery, calculate the integrated lithium iron balance target SOC = the internal lithium iron balance target SOC of the lithium iron phosphate battery - (Q3 - Q4) / (SOH2 * C2), and then perform integrated balancing on all lithium iron monomer batteries with SOC higher than the integrated lithium iron balance target SOC for an equilibrium duration corresponding to the equilibrium capacity of [(SOC - integrated lithium iron balance target SOC) * (SOH2 * C2)], and set the equilibrium duration of lithium iron monomer batteries with SOC lower than the integrated lithium iron balance target SOC to 0; Perform internal balancing on ternary monomer batteries with SOC higher than the ternary internal balance target SOC according to the ternary internal balance target SOC, and set the equilibrium duration of ternary monomer batteries with SOC lower than the ternary internal balance target SOC to 0; If the battery capacity difference of the ternary lithium battery is less than the battery capacity difference of the lithium iron phosphate battery, calculate the integrated ternary balance target SOC = the ternary internal balance target SOC of the ternary lithium battery - (Q4 - Q3) / (SOH1 * C1), and then perform integrated balancing on all ternary monomer batteries with SOC higher than the integrated ternary balance target SOC for an equilibrium duration corresponding to the equilibrium capacity of [(SOC - integrated ternary balance target SOC) * (SOH1 * C1)], and set the equilibrium duration of ternary monomer batteries with SOC lower than the integrated ternary balance target SOC to 0; Perform internal balancing on lithium iron monomer batteries with SOC higher than the lithium iron internal balance target SOC according to the lithium iron phosphate internal balance target SOC, and set the equilibrium duration of lithium iron monomer batteries with SOC lower than the lithium iron internal balance target SOC to 0; Among them, Q3 is the battery capacity difference of the ternary lithium battery, Q3 = (a% - ternary internal balance target SOC) * SOH1 * C1, Q4 is the battery capacity difference of the lithium iron phosphate battery, Q4 = (1 - lithium iron internal balance target SOC) * SOH2 * C2, SOH1 is the SOH of the ternary lithium battery, C1 is the battery capacity of the ternary lithium battery at 25°C, SOH2 is the SOH of the lithium iron phosphate battery, C2 is the battery capacity of the lithium iron phosphate battery at 25°C, and a% is the external balance target SOC of the ternary lithium battery.

4. The equalization method according to claim 2, characterized in that, If the ternary lithium battery satisfies the OCV correction condition and the lithium iron phosphate battery does not satisfy the OCV correction condition, determine the balancing method for different types of the monomer batteries and the equilibrium duration corresponding to the balancing method, including: If the ternary lithium battery is performing integrated balancing according to the historical equilibrium duration, both the ternary lithium battery and the lithium iron phosphate battery continue to balance according to their respective historical equilibrium durations; If the ternary lithium battery has not performed integrated balancing, determine the updated equilibrium duration of the ternary lithium battery according to the ternary internal balance target SOC, and the lithium iron phosphate battery continues to balance according to its respective historical equilibrium durations.

5. The equalization method according to any one of claims 2 to 4, characterized in that Determining whether all the single cells satisfy the OCV correction condition according to the SOC of the single cells includes: Interpolating the SOC using the voltage of the single cell as the OCV to obtain the relationship curve between the single cell and the SOC, so as to obtain the SOC of each single cell; If all the lithium iron phosphate single cells of the lithium iron phosphate battery are in the "non-plateau period" of the relationship curve, or some of the lithium iron phosphate single cells are in the "non-plateau period", it is determined that all the single cells satisfy the OCV correction condition; If all the lithium iron phosphate single cells of the lithium iron phosphate battery are in the "plateau period" of the relationship curve, it is determined that the ternary lithium battery satisfies the OCV correction condition, and the lithium iron phosphate battery does not satisfy the OCV correction condition.

6. An equalization device for a battery series-parallel system, the battery series-parallel system comprising a ternary lithium battery and a lithium iron phosphate battery, characterized in that, The equalization device implements the equalization method of the battery parallel-series system as described in claim 1, including: An acquisition module, configured to acquire the SOC state of the single cells in the battery parallel-series system; A determination module, configured to determine the equalization method of the single cells and the equalization target SOC corresponding to the equalization method according to the SOC of the single cells; A control module, configured to determine the equalization capacity of the single cells according to the equalization target SOC, and calculate the equalization duration according to the equalization capacity, so as to implement the equalization control of the single cells.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the equalization method of the battery parallel-series system as described in any one of claims 1-5.

8. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the equalization method of the battery parallel-series system as described in any one of claims 1 to 5.

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