Different battery hybrid method based on BMS

Abstract

The BMS-based differential battery mixing method provided by the present invention is a dynamic mixing method that takes power supply balance into consideration. Before powering an electric device each time, the number of times a battery module is used as a simulated mixing object is limited by searching for a simulated mixing object, so that each battery module is first balanced in terms of the number of times used; then, by calculating the mixing effectiveness of the simulated balanced power group on the simulated mixing object and the mixing acceptance of the simulated mixing object on the simulated balanced power group, an available balanced power group constructed for each simulated mixing object is conducive to reducing the internal resistance and power supply loss of the simulated mixing object, thereby improving the rationality of screening available balanced power groups; by predicting the power demand of the electric device and taking the optimal mixing feasibility as a prerequisite, through steps C1-C3, the optimal available balanced power group for the next power supply to the electric device can be quickly identified among multiple available balanced power groups that can be mixed with the same simulated mixing object, thereby reducing power supply loss.

Description

Technical Field

[0001] The present invention relates to the field of battery application technology, and in particular to a method for mixing and merging differential batteries based on a BMS. Background Art

[0002] After the battery module is fully charged, it (defined as the hybrid object) is mixed and combined with other battery modules (defined as the balanced power source) in parallel to form a hybrid battery pack. The more times it powers electrical equipment, the less available battery capacity and the weaker the power supply capacity. Due to the increase in the internal resistance of the battery and other reasons, its power loss will gradually increase. For a single battery module, this power loss is usually small and is usually ignored in practical applications. However, when the number of battery modules in the hybrid battery pack is large and the power loss is large, ignoring the overall power loss of the battery pack will significantly increase the electricity cost in long-term applications, so it needs to be paid special attention.

[0003] However, the large power loss of the battery module does not mean that its power supply value is low. When the power demand of the power-consuming equipment is small, the battery module with large power loss and weak power supply capacity may also be able to meet the power supply demand of the power-consuming equipment. When there are fewer available battery modules, the battery module with large power loss but still has power supply value can continue to be used as the mixed object. In addition, different balanced power sources are mixed with the same mixed object. Due to the different internal resistance and available capacity of the balanced power source, the power supply capacity of the mixed battery group after mixing is usually different. The higher the power supply capacity of the mixed battery group, the higher the feasibility of mixing these balanced power sources with the mixed object, and vice versa. This is reflected in that if the power supply capacity of each balanced power source is greater than the mixed object (for example, the available capacity of the battery of the balanced power source is greater than the available capacity of the battery of the mixed object), these balanced power sources and the mixed object will be charged after switching from the power-off isolation state to the mixed state, so that the power supply capacity of the mixed object is increased and the power supply loss is reduced, but at the same time, the power supply capacity of the balanced power source is weakened and the power supply loss is increased. When the charging reaches the battery terminal voltage balance, the overall power supply capacity of the mixed battery group may be increased and the power supply loss is reduced. Therefore, even if the individual power supply capacity of the hybrid object is poor and the power supply loss is large, the hybrid battery pack after being hybridized with the balanced power source also has a high power supply value as long as it can meet the power demand of the electrical equipment.

[0004] Therefore, each time the electrical equipment is powered by a mixed mode that switches from a power-off isolation state to a mixed state, under the premise of considering power supply balance, how to screen out the mixed object that can meet the power demand of the electrical equipment from a large number of battery modules, and how to find a balanced power source with a high mixing feasibility with the mixed object from a large number of battery modules to form a mixed battery pack, have become technical problems that need to be urgently solved in this field. Summary of the invention

[0005] The present invention aims to find a mixing object that can meet the future power demand of the power equipment from a large number of battery modules with different performances, and to find a balanced power source with a high mixing feasibility with the mixing object from a large number of battery modules, so as to achieve balanced power supply to the power equipment every time, reduce battery failure rate, and reduce power supply loss. A differential battery mixing method based on BMS is provided.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A BMS-based mixed method for different batteries is provided. After each power supply to the power-consuming equipment is completed, the BMS battery management system performs the following steps:

[0008] S1, according to the historical power supply data of the difference battery group to the electrical equipment in the current charge and discharge cycle, by calculating the minimum feasibility of mixing and merging, to find the object to be mixed and merged in the difference battery group;

[0009] S2, constructing an available balanced power group for each of the proposed mixed-in objects by calculating the effectiveness of the proposed balanced power group for the proposed mixed-in objects, and calculating the acceptance of the proposed mixed-in objects for the proposed balanced power group, and adding the available balanced power group to the set of available balanced power groups respectively associated with each of the proposed mixed-in objects;

[0010] S3, according to the power demand prediction result of the power-consuming device, identifying the available balanced power group that will supply power to the power-consuming device next time from the set of available balanced power groups associated with each of the proposed mixed-and-merged objects, and then mixing and merging the proposed mixed-and-merged objects associated with the available balanced power groups to form a mixed-and-merged battery group that will supply power to the power-consuming device next time;

[0011] After each power supply is completed, the BMS battery management system switches each battery module in the difference battery pack to a power-off isolation state.

[0012] Preferably, in step S1, one charge-discharge cycle is: during the interval between two consecutive constant current full charging operations on the difference battery pack, the charge-discharge process of the difference battery pack is one charge-discharge cycle;

[0013] The method for finding the quasi-mixed object in the difference battery pack comprises the steps of:

[0014] A1, obtaining a battery pack used to calculate the minimum hybrid feasibility;

[0015] A2, calculating the minimum hybrid feasibility according to the historical hybrid data of the battery pack;

[0016] A3, simulating an excitation source according to the historical hybrid data used to calculate the minimum hybrid feasibility, and then using the excitation source to separately charge and excite each of the remaining battery modules in the difference battery pack except the dependent unit in the basis battery pack, so as to obtain the available capacity change rate of each of the battery modules after the excitation;

[0017] A4, determines whether the difference between the available capacity change rate of each battery module and the second ratio used to calculate the minimum hybrid feasibility is greater than a preset difference threshold. If so, the battery module is added to the set of simulated hybrid objects as the simulated hybrid object for powering the electrical equipment next time.

[0018] Preferably, the calculation in step A1 is based on the method for obtaining the battery pack, comprising the steps of:

[0019] A11, select each battery module that is used as a historical mixing object at least twice from the difference battery group, and then construct a power loss list corresponding to each of the selected battery modules, and the construction method is:

[0020] According to the historical mixing and merging sequence, the power loss of the historical mixed and merged battery group containing the battery module in supplying power to the electrical equipment is sorted to obtain the power loss list corresponding to each battery module;

[0021] A12, for each of the battery modules, determine whether the power loss of each of the power loss lists associated with the battery module increases with the increase of the number of historical mixing times.

[0022] If yes, the battery module is added to the dependent unit set for minimum hybrid feasibility calculation, and then the process goes to step A13;

[0023] If not, determining that the battery module is a non-dependent unit for minimum hybrid feasibility calculation;

[0024] A13, sort the battery modules in the dependent unit set from large to small according to the number of historical mixing and merging times to form a sorted list, and then obtain the historical mixed and merged battery group of the battery module ranked first in the sorted list at the last historical mixing and merging, as the basis battery group for calculating the minimum mixing and merging feasibility.

[0025] Preferably, the power loss is calculated by the following formula (1):

[0026]

[0027] In formula (1), The power supply loss of the historical mixed battery pack in supplying power to the electrical equipment;

[0028] The first The change in available capacity of each battery module during power supply;

[0029] Indicates the number of battery modules in the historical mixed battery pack;

[0030] Indicates the amount of electricity consumed by the electrical equipment during the power supply period.

[0031] Preferably, in step A2, the historical mixing data based on the battery group used to calculate the minimum mixing feasibility includes: the first internal resistance change of the dependent unit and the battery available capacity change when the dependent unit in the battery group and the historical balanced power group are mixed from the beginning to the battery terminal voltage balance, the second internal resistance change of the historical balanced power group, the charging time of the dependent unit from the beginning of mixing to the battery terminal voltage balance, and the discharge current of each historical balanced power supply in the historical balanced power group.

[0032] Preferably, in step A2, the minimum hybrid feasibility is: a weighted sum of a first ratio of the first internal resistance change to the second internal resistance change and a second ratio of the battery available capacity change of the dependent unit to the charging time;

[0033] The second internal resistance change is a weighted sum of the internal resistance changes of the battery modules constituting the historical balanced power supply from the beginning of mixing to the time when the battery terminal voltage is balanced.

[0034] Preferably, in step A3, the excitation source includes a plurality of charging links respectively corresponding to a historical balanced power source in the battery pack, each charging link having a charging current corresponding to the historical balanced power source for mixed charging of the dependent unit; each charging link excites each battery module with the same charging time of the dependent unit as the historical balanced power source group in the battery pack; after the charging excitation, the rate of change of the available capacity of the battery module is: the third ratio of the change in the available capacity of the battery module to the charging time.

[0035] Preferably, in step S2, the method for constructing the available balanced power supply group for each of the quasi-mixed objects comprises the following steps:

[0036] B1, specifying the quasi-mixed object used to construct the proposed balanced power source group from the quasi-mixed object set;

[0037] B2, randomly extracting the same number of battery modules as the historical balanced power sources in the historical balanced power source group in the battery group used to calculate the minimum mixed feasibility from the specified remaining set of the proposed mixed objects as the proposed balanced power sources;

[0038] B3, connecting the extracted balanced power sources to be used in parallel to form a balanced power group to be used, and then mixing the balanced power group to be used with the object to be mixed and merged, and monitoring the mixed and merged data until each battery module in the balanced power group to be used reaches a battery terminal voltage balance state;

[0039] B4, calculating the feasibility of mixing and merging the planned balanced power source group and the planned mixed and merged object according to the mixed and merged data;

[0040] B5, judging whether the mixed-merge feasibility is greater than the minimum mixed-merge feasibility,

[0041] If yes, determining that the proposed balanced power group is the available balanced power group available to the proposed mixed and merged object, and adding it to the available balanced power group set associated with the proposed mixed and merged object;

[0042] If not, the process returns to step B2 to extract battery modules again to form different balanced power groups to be used, until it is no longer possible to form different balanced power groups to be used.

[0043] Preferably, in step S3, the method of identifying the available balanced power group for supplying power to the electrical device next time from the available balanced power group set associated with each of the objects to be mixed and merged comprises the following steps:

[0044] C1, filtering out the available balanced power groups whose power supply is less than the predicted power demand in the sets of available balanced power groups respectively associated with the proposed mixed-merging objects, and then arranging the remaining available balanced power groups from high to low according to the mixed-merging feasibility with the associated proposed mixed-merging objects to form a first list;

[0045] C2, calculating the difference between the battery performance of the pseudo-mixed objects associated with each of the available balanced power groups remaining after filtering in step C1 and the dependent units in the battery group, and arranging the pseudo-mixed objects from high to low according to the difference to form a second list;

[0046] C3, for a second element in the second list having the same ranking as the first element in the first list, determining whether the number of element combinations having an association relationship between the second element and the first element is at least "1",

[0047] If so, extract the element combination at the front of the sorting list, mix and merge them, and use them as the mixed and merged battery group for supplying power to the electrical device next time;

[0048] If not, the proposed hybrid object ranked first in the first list is hybridized with the available balanced power source group with the maximum hybrid feasibility to form the hybrid battery group for the next power supply.

[0049] Preferably, it is determined whether the number of times the same battery module is added to the dependent unit set is greater than a preset number threshold, and if so, the battery module is determined to be a suspected faulty battery;

[0050] The types of battery modules in the differential battery pack include any one or more of iron-lithium batteries, ternary lithium batteries, and sodium-ion batteries.

[0051] The present invention has the following beneficial effects:

[0052] 1. The BMS-based differential battery mixing method provided in this embodiment is a dynamic mixing method that considers power supply balance. Before powering the electrical equipment each time, the number of times the battery module is used as the object of mixing is limited by searching for the object of mixing, so that each battery module in the differential battery group after each full charge is first balanced in the number of times used; then, by calculating the mixing effectiveness of the proposed balanced power group for the object of mixing, and the mixing acceptance of the proposed balanced power group by the proposed mixed object, the available balanced power group constructed for each proposed mixed object is conducive to reducing the internal resistance and power supply loss of the proposed mixed object, and improving the rationality of the screening of available balanced power groups; by predicting the power demand of the electrical equipment and taking the optimal mixing feasibility as the premise, through steps C1-C3, the optimal available balanced power group for the next power supply to the electrical equipment can be quickly identified among the multiple available balanced power groups that can be mixed by the same proposed mixed object, thereby reducing the power supply loss.

[0053] 2. With the restriction condition of full constant current charging of the difference battery group, through steps A11-A13, the historical mixed-merge object (dependent unit) with poor current power supply capacity and large power loss is found, and the basis battery group with the minimum mixed-merge feasibility with the historical mixed-merge object is found. In order to achieve balanced power supply of each battery module in the difference battery group and reduce power loss, in the next power supply to the power-consuming equipment, on the condition of meeting the next power demand of the power-consuming equipment, in the set of quasi-mixed objects with higher power supply capacity than the dependent unit and lower power loss than the dependent unit, the battery module with a battery performance difference degree higher than the difference degree threshold with the dependent unit is preferentially selected as the quasi-mixed object, and an available balanced power group set is constructed for each quasi-mixed object through steps B1-B5, and then an available balanced power group that can meet the next power demand of the power-consuming equipment is matched through steps C1-C5, so as to achieve balanced power supply of each battery module in the difference battery group to the power-consuming equipment.

[0054] 3. The minimum feasibility of mixing and merging is calculated based on the effectiveness of the historical balanced power group in reducing the internal resistance of the dependent unit (characterized by the first ratio) and the acceptance of the dependent unit to the historical balanced power group to reduce its internal resistance (characterized by the second ratio) when the historical balanced power group in the battery group is mixed and merged with the dependent unit in the battery group until the battery terminal voltage is balanced. This expresses the minimum requirement for mixing and merging the difference batteries under the condition of meeting the historical power demand of the power-consuming equipment. That is, in the next mixed and merged battery group that supplies power to the power-consuming equipment, the effectiveness of the formed available balanced power group in reducing the internal resistance of the selected object to be mixed and merged is higher than the first ratio, and the acceptance of the object to be mixed and merged to reduce its internal resistance by the available balanced power group is higher than the second ratio. In this way, in each power supply to the power-consuming equipment, by reducing the selection of battery modules with poor power supply capacity and large power supply loss, each difference battery can achieve balanced power supply to the same power-consuming equipment, thereby extending the service life of each battery module.

[0055] 4. In the process of searching for the quasi-mixing object, the dependent unit in the battery pack used to calculate the minimum feasibility of mixing is used as a reference, and the battery module with similar or higher battery performance than the dependent unit is searched in the difference battery pack as the quasi-mixing object. The search is realized by charging each battery module. The excitation source performs separate charging excitations on each battery module for different charging currents and the same charging time of the dependent unit according to each historical balanced power source in the battery pack, and expresses the degree of acceptance of the battery module for charging excitation using the same charging conditions of the dependent unit through the rate of change of available capacity, so as to evaluate the similarity of the battery module's current battery performance with that of the dependent unit. Then, the battery module with similar or higher battery performance than the dependent unit is used as the quasi-mixing object, so as to avoid the problem that the power supply times of each battery module in the difference battery pack become more and more unbalanced and the power supply loss becomes larger and larger due to the use of battery modules with worse performance than the dependent unit in the next power supply to the electrical equipment.

[0056] 5. Through steps B1-B5, the effectiveness of the proposed balanced power supply group for the proposed mixed object and the acceptance of the proposed mixed object to the proposed balanced power supply group are calculated, so as to realize the rapid and accurate search for the available balanced power supply group for the proposed mixed object, which is beneficial to improve the balance of the power supply to the electrical equipment by the mixed battery group found in the subsequent steps C1-C3.

[0057] 6. Through steps C1-C3, a rapid and accurate search is achieved for the hybrid battery pack that will power the electrical equipment next time.

[0058] 7. When the number of times the same battery module is added to the dependent unit set is greater than the preset number threshold, the battery module can be determined to be a suspected faulty battery. Before each power supply to the electrical equipment, the dependent unit is found as the basis for judging whether the battery is suspected of having a fault in the process of searching for the quasi-mixed objects in steps A1-A4, so that the process of finding a suspected faulty battery is simplified to counting the number of times the same battery module is added to the dependent unit set, and finding a suspected faulty battery is simpler, more efficient, and more intelligent. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0060] Figure 1 It is a diagram of the implementation steps of the BMS-based differential battery mixing method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0061] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0062] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on this patent; in order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0063] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0064] In the description of the present invention, unless otherwise clearly specified and limited, if the term "connection" or the like appears to indicate the connection relationship between components, the term should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] The embodiment of the present invention provides a method for mixing and merging different batteries based on a BMS (BATTERY MANAGEMENT SYSTEM). After each power supply to the power-consuming device is completed, the BMS battery management system executes the following steps: Figure 1 The following steps are shown:

[0066] S1, according to the historical power supply data of the difference battery group to the power-consuming equipment in the current charge and discharge cycle, by calculating the minimum feasibility of mixing and merging, to find the object to be mixed and merged in the difference battery group;

[0067] It should be noted that one charge-discharge cycle is: during the interval between two consecutive constant current full charge operations on the difference battery pack, the charge-discharge process of the difference battery pack is one charge-discharge cycle. At this moment, the BMS controls the external power supply to perform constant current full charging on each battery module in the differential battery pack. After full charging, based on the prediction results of each power demand of the power-consuming equipment, the BMS takes balanced power supply as the goal, and selects the battery modules that will power the power-consuming equipment next time from the differential battery pack to form a mixed battery pack. In this way, through repeated predictions of the power supply demand of power-consuming equipment and repeated construction of mixed battery packs, the BMS's power supply calls for each battery module in the differential battery pack will become more and more balanced. When the differential battery pack meets the conditions for constant current full charging again, the BMS controls the external power supply to The constant current full charging operation is performed again on the different battery packs at any time. Constant current full charging starts from the moment the full charging is completed until The constant current full charging operation is performed again at this moment, and this period is one charge and discharge cycle.

[0068] There are two types of discharge in a charge-discharge cycle: 1. The discharge of the hybrid battery pack to power the electrical equipment; 2. The discharge of the balanced power group in the hybrid battery pack as the hybrid object. In the following content, the definitions of the hybrid object and the balanced power group will be explained.

[0069] There are also two types of charging in a charge-discharge cycle: 1. When the mixed object is mixed with the balanced power group, the balanced power group charges the mixed object; 2. The simulated excitation source is the simulated charging of the mixed object.

[0070] In step S1, the method for finding the quasi-mixing object in the difference battery pack includes the following steps:

[0071] A1, obtaining a battery pack for calculating the minimum hybrid feasibility, wherein the obtaining method specifically comprises the following steps:

[0072] A11, select each battery module that has been used as a historical mixing object at least twice from the difference battery group, and then construct a power loss list corresponding to each selected battery module, and the construction method is:

[0073] According to the historical mixing and merging sequence, the power loss of the historical mixed and merged battery group containing the battery modules for powering the electrical equipment is sorted to obtain a power loss list corresponding to each battery module;

[0074] For example, during one charge and discharge cycle, at the current time point when predicting the next power demand of the power-consuming device, the battery modules 005, 001, and 002 in the difference battery group have been used as historical mixed objects 3 times, 2 times, and 2 times respectively. Then, the battery modules 005, 001, and 002 are screened out from the difference battery group, and then the power loss lists corresponding to the battery modules 005, 001, and 002 are constructed. The construction method is as follows:

[0075] Suppose that the historical mixed-and-combined battery groups containing battery module 005 are (battery module 001, battery module 003, battery module 005), (battery module 001, battery module 002, battery module 005), and (battery module 002, battery module 004, battery module 005), among which the historical mixed-and-combined battery group (battery module 001, battery module 003, battery module 005) is mixed the earliest during this charge and discharge cycle, followed by (battery module 001, battery module 002, battery module 005), and finally (battery module 002, battery module 004, battery module 005). Suppose also that the power supply losses of the historical mixed-and-combined battery groups (battery module 001, battery module 003, battery module 005), (battery module 001, battery module 002, battery module 005), and (battery module 002, battery module 004, battery module 005) to the same electrical equipment are respectively , , , then according to the above sorting rules, the power loss list corresponding to the battery module 005 is expressed in the following Table 1:

[0076] Table 1

[0077]

[0078] The power loss list corresponding to battery module 001 is expressed in Table 2 below:

[0079] Table 2

[0080]

[0081] The power loss list corresponding to the battery module 002 is expressed in the following Table 3:

[0082] Table 3

[0083]

[0084] A12, for each battery module, determine whether each power loss in the associated power loss list increases with the increase of its historical mixing times.

[0085] If yes, then add the battery module to the dependent unit set for minimum hybrid feasibility calculation, and then go to step A13;

[0086] If not, the battery module is determined to be a non-dependent unit with minimum hybrid feasibility;

[0087] Assumptions , then according to the judgment rule of step A12, each power loss in the power loss list associated with battery module 005 does not increase with the increase of its historical mixing times, indicating that when the historical mixing battery group containing battery module 005 is used to power the power-consuming device for multiple times, the mixing feasibility of battery module 005 and each historical balanced power group does not decrease successively with the increase of the historical mixing times, indicating that in each historical mixing, there is at least one experience of successfully saving the battery module 005 whose power supply capacity decreases with the increase of the mixing times by constructing the historical available balanced power group of battery module 005, indicating that the power supply value of battery module 005 to the power-consuming device is not the lowest among the battery modules in the difference battery group. Therefore, battery module 005 is not added to the dependent unit set.

[0088] It should be noted here that the construction of the dependent unit set has two purposes: first, to find the basis battery group for calculating the minimum hybrid feasibility; second, to judge whether the battery module is a suspected faulty battery based on the number of times the same battery module is added to the dependent unit set, so as to realize the rapid identification of the suspected faulty battery.

[0089] Similarly, according to the judgment rule of step A12, each power loss in the power loss list associated with battery module 001 does not increase with the increase of its historical mixing times, so battery module 001 is also not added to the dependent unit set. However, each power loss in the power loss list associated with battery module 002 increases with the increase of its historical mixing times, so battery module 002 is added to the dependent unit set.

[0090] A13, sort the battery modules in the dependent unit set according to the number of historical mixing and merging times from large to small to form a sorted list, and then obtain the historical mixed and merged battery group of the battery module ranked first in the sorted list at the last historical mixing and merging time, as the basis battery group for calculating the minimum mixing and merging feasibility.

[0091] For example, assuming that after step A12, the battery modules in the dependent unit set include battery modules 002 and 008, wherein the historical mixing times of battery module 002 is "2", and the historical mixing times of battery module 008 is "2", then the formed sorting list is shown in Table 4 below:

[0092] Table 4

[0093]

[0094] According to the extraction rule of the historical mixed battery group in step A13, extract the historical mixed battery group of battery module 002 or 008 at the last time in history. Assuming that the historical mixed battery group of battery module 002 at the last time in history is (battery module 002, battery module 004, battery module 005), then extract the historical mixed battery group (battery module 002, battery module 004, battery module 005) as the basis battery group for calculating the minimum mixed feasibility.

[0095] It should also be noted that the power loss of the hybrid battery pack is calculated using the following formula (1):

[0096]

[0097] In formula (1), The power supply loss of the historical hybrid battery pack to power the electrical equipment;

[0098] The first in the history of mixed battery packs The change in available capacity of each battery module during power supply;

[0099] Indicates the number of battery modules in the historical mixed battery pack;

[0100] Indicates the amount of electricity consumed by an electrical device during the power supply period.

[0101] After going through steps A11-A13, after obtaining the reference battery group for calculating the minimum hybrid feasibility, the method of finding the quasi-hybrid object in the difference battery group proceeds to step:

[0102] A2, calculate the minimum hybrid feasibility based on the historical hybrid data of the battery pack;

[0103] The historical mixing data based on the battery group used to calculate the minimum mixing feasibility includes: the first internal resistance change of the dependent unit and the battery available capacity change from the start of mixing to the battery terminal voltage balance between the dependent unit in the battery group and the historical balanced power group in the battery group, the second internal resistance change of the historical balanced power group, the charging time of the dependent unit from the start of mixing to the battery terminal voltage balance, and the discharge current of each historical balanced power supply in the historical balanced power group.

[0104] The following is an example of the historical mixed data of the battery pack:

[0105] For example, the battery module 002 is determined to be a dependent unit after steps A11-A12, and the historical mixed battery group (battery module 002, battery module 004, battery module 005) is the basis battery group for calculating the minimum mixed feasibility, and battery modules 004 and 005 constitute a historical balanced power group mixed with battery module 002 as a dependent unit. After battery modules 004 and 005 are historically mixed with battery module 002 as a dependent unit, the historical balanced power group begins to discharge battery module 002, and battery module 002 is charged from the historical balanced power group. When the three battery modules reach a balance in battery terminal voltage, the charging time is assumed to be When battery modules 004 and 005 are discharged at a constant voltage, the discharge currents are assumed to be , At the beginning of hybridization, the internal resistance of battery module 002 is assumed to be , when the battery terminal voltage is balanced, assuming the internal resistance is , the first internal resistance change is At the beginning of the hybrid, the internal resistance of the historical balanced power group composed of battery modules 004 and 005 is assumed to be When the battery terminal voltage is balanced, the internal resistance of the historical balanced power group is assumed to be , then the second internal resistance change is The change in available battery capacity of battery module 002 is assumed to be (the difference between the available battery capacity when the battery terminal voltage is balanced and the available battery capacity when the mixing starts), then the historical mixing data of the battery pack includes , , , , , .

[0106] In step A2, the calculation of the minimum feasibility of mixing and merging is determined by two factors: first, the effectiveness of the historical balanced power group in the battery pack in reducing the internal resistance of the dependent unit; second, the acceptance of the dependent unit to the historical balanced power group for reducing its internal resistance. Since the types and performances of the battery modules in the difference battery pack are different, the dependent unit has different acceptance of mixing and merging of the historical balanced power groups composed of battery modules of different types and performances. This acceptance, in this embodiment, is defined as the acceptance of the dependent unit to reduce its internal resistance by the historical balanced power group.

[0107] The first of the two factors that determine the minimum hybrid feasibility is characterized by the ratio of the first internal resistance change to the second internal resistance change (defined as the first ratio) in this embodiment; the second factor is characterized by the ratio of the battery available capacity change of the dependent unit to the charging time (defined as the second ratio). The minimum hybrid feasibility is expressed as the weighted sum of the first ratio and the second ratio. For example, in the above example, and The ratio (first ratio) and and It should be noted here that when calculating the weighted sum, the weights assigned to the first ratio and the second ratio can be obtained by solving the historical mixed data of each historical mixed battery pack through relevant functions and algorithms. Since the weighting method of the first ratio and the second ratio is not within the scope of the rights protection claimed by the present invention, it will not be described in detail.

[0108] After step A2, after calculating the minimum hybrid feasibility, the method of finding the quasi-hybrid objects in the different battery groups proceeds to step:

[0109] A3, simulate the excitation source according to the historical hybrid data used to calculate the minimum hybrid feasibility, and then use the simulated excitation source to charge and stimulate each battery module in the difference battery pack except the dependent unit in the battery pack separately to obtain the change rate of the available capacity of each battery module after the stimulation.

[0110] It should be noted here that the excitation source includes several charging links corresponding to a historical balanced power source in the battery pack, and one charging link has a charging current for mixed charging of dependent units with the corresponding historical balanced power source; each charging link excites each battery module with the same charging time of the dependent unit based on the historical balanced power source group in the battery pack; after the charging excitation, the rate of change of the available capacity of the battery module is: the third ratio of the change in the available capacity of the battery module to the charging time.

[0111] For example, in the above-mentioned example, the historical balanced power supply group includes historical balanced power supplies 004 and 005, and the historical balanced power supplies 004 and 005 are the charging currents of the battery module 002 as the dependent unit for historical mixed charging, respectively. , , then the discharge currents output by the two charging links simulated by the excitation source are , The charging time for each battery module in the difference battery pack except the battery module 002 as the dependent unit is The calculation method of the change rate of the available battery capacity of each battery module after charging stimulation has been explained in the above example and will not be repeated here.

[0112] After step A3, the available capacity change rate of each battery module is obtained through charging stimulation, and the method of finding the quasi-mixing object in the difference battery group is transferred to step:

[0113] A4, determining the ratio of the available capacity change rate of each battery module to the second ratio used to calculate the minimum hybrid feasibility ( and is greater than a preset difference threshold; if so, the battery module is added to the set of quasi-mixed objects as a quasi-mixed object for supplying power to the electrical device next time.

[0114] It should be noted here that if the difference is greater than the difference threshold, it means that the power supply performance of the battery module is suspected to be better than that of the dependent unit. The greater the difference is greater than the difference threshold, the more excellent the performance of the battery module is compared with the dependent unit. Using these batteries as the simulated mixed-in objects for the next power supply can avoid using battery modules that have been mixed-in too many times as mixed-in objects again, and reduce the reuse of these battery modules that usually have large power supply losses and obvious performance degradation, so as to achieve balanced power supply to each battery module in the difference battery pack.

[0115] After finding the target to be mixed and merged in the difference battery group through the above step S1, the difference battery mixing and merging method based on BMS provided in this embodiment is as follows: Figure 1 As shown, proceed to step:

[0116] S2, by calculating the effectiveness of the proposed balanced power group on the proposed mixed object, and calculating the acceptance of the proposed mixed object to the proposed balanced power group, construct an available balanced power group for each proposed mixed object, and add it to the available balanced power group set associated with each proposed mixed object.

[0117] Specifically, the method for constructing an available balanced power supply group for each quasi-mixed object includes the following steps:

[0118] B1. Specify the simulated mixed objects used to construct the simulated balanced power group from the simulated mixed object set. For example, assuming that the simulated mixed object set includes battery modules 009, 010, 011, and 012, when it is necessary to construct the simulated balanced power group for battery module 009, first specify battery module 009 from the simulated mixed object set.

[0119] B2, randomly extract the same number of battery modules as the historical balanced power sources in the historical balanced power source group in the basis battery group used to calculate the minimum mixed feasibility from the specified remaining set of objects to be mixed and merged as the balanced power sources to be used. For example, the historical balanced power source group in the basis battery group in the above example includes battery modules 004 and 005, and the number of historical balanced power sources in the basis battery group is "2", then randomly extract 2 battery modules from the example set of objects to be mixed and merged as the balanced power sources to be used for the object to be mixed and merged 009, such as extracting battery modules 010 and 011, or 010 and 012, or 011 and 012 as the balanced power sources to be used for the battery module 009.

[0120] B3, connect the extracted balanced power sources to be used in parallel to form a balanced power group to be used, for example, connect the extracted battery modules 010 and 011 in parallel to form a balanced power group to be used. Then, after the balanced power group to be used is mixed and merged with the object to be mixed and merged, the mixed and merged data is monitored until the battery modules in the balanced power group to be used reach a balanced state of battery terminal voltage.

[0121] What data the mixed data includes has been explained in the above example of the historical mixed data of the battery pack, and will not be repeated here.

[0122] B4, the feasibility of mixing and merging the proposed balanced power source group and the proposed mixed and merging object is calculated according to the mixed and merging data. The calculation method of the mixed and merging feasibility is the same as the calculation method of the minimum mixed and merging feasibility in the above example, which will not be repeated.

[0123] B5, determine whether the mixed feasibility is greater than the minimum mixed feasibility,

[0124] If so, the proposed balanced power supply group is determined to be an available balanced power supply group available to the proposed mixed-merging object, and is added to the set of available balanced power supply groups associated with the proposed mixed-merging object;

[0125] If not, return to step B2 and re-extract battery modules to form a different intended balanced power group, for example, extract battery modules 010 and 012 to form a proposed balanced power group different from the intended balanced power group composed of 010 and 011, until it is no longer possible to continue to form different intended balanced power groups.

[0126] Through the above steps B1-B5, a set of available balanced power groups associated with each object to be mixed and merged is formed. However, the set of available balanced power groups includes at least one available balanced power group. In order to further improve the balance of power supply of different battery groups, it is particularly important to select the best available balanced power group from the set of available balanced power groups and combine it with the corresponding object to be mixed and merged to form a mixed battery group to power the electrical equipment next time. In order to select the best available balanced power group, in this embodiment, by predicting the demand for power consumption of the electrical equipment next time, and taking the condition that the demand for power consumption of the electrical equipment next time can be met after mixing and merging, and taking the premise that the object to be mixed and merged has the highest acceptance of the available balanced power group to prompt it to reduce its internal resistance, and the available balanced power group has the greatest effectiveness in reducing the internal resistance of the object to be mixed and merged, the technical problem is solved through step S3. Specifically:

[0127] After step S2, the available balanced power supply group set associated with each of the objects to be mixed and merged is found. Figure 1 As shown, the BMS-based mixed battery method provided in this embodiment is transferred into the steps:

[0128] S3, based on the prediction result of the power demand of the power-consuming device for the next time, identify the available balanced power group that will supply power to the power-consuming device next time from the set of available balanced power groups associated with each proposed mixed-and-merged object, and then mix and merge the proposed mixed-and-merged objects associated with the available balanced power group to form a mixed-and-merged battery group that will supply power to the power-consuming device next time.

[0129] It should be noted that there are many existing methods for predicting the next power demand of electrical equipment, such as predicting by curve fitting based on historical power consumption data. Since the power consumption prediction method for electrical equipment is not within the scope of the present invention, it will not be explained.

[0130] In this embodiment, the method for identifying an available balanced power group for supplying power to an electric device next time from the available balanced power group set associated with each to-be-mixed object includes the following steps:

[0131] C1, filtering out the available balanced power groups whose power supply is less than the predicted power demand in the set of available balanced power groups associated with each proposed mixed-merging object, and then arranging the remaining available balanced power groups from high to low according to the mixed-merging feasibility with the associated proposed mixed-merging object to form a first list;

[0132] For example, assume that the available balanced power supply groups associated with the proposed mixed objects such as battery modules 009, 010, 011, and 012 are expressed as X, Y, Z, and W, respectively, where set X includes 2 available balanced power supply groups, x1 and x2; set Y includes 1 available balanced power supply group, y1; set Z includes 3 available balanced power supply groups, z1, z2, and z3; and set W includes 2 available balanced power supply groups, w1 and w2. Assuming that the predicted power demand is Q, and the power supply of x2, z2, z3, and w2 is less than Q, x2, z2, z3, and w2 are filtered out, and the remaining x1, y1, z1, and w1 are arranged from high to low according to the mixed feasibility with the respectively associated proposed mixed objects 009, 010, 011, and 012, to form the first list. Assuming that the feasibility of the combination of 009 and x1 is greater than the feasibility of the combination of 010 and y1, the feasibility of the combination of 011 and z1, and the feasibility of the combination of 012 and w1, the first table is expressed as shown in Table 5 below:

[0133] Table 5

[0134]

[0135] C2, calculating the difference between the pseudo-mixed objects associated with each available balanced power group remaining after filtering in step C1 and the battery performance of the dependent unit in the battery group, and arranging each pseudo-mixed object from high to low according to the difference to form a second list;

[0136] For example, the battery performance difference between the battery module 009 in Table 5 and the battery module 002 as the dependent unit is greater than the battery performance difference between the battery module 011 and the battery module 002, greater than the difference between the battery module 010 and the battery module 002, and greater than the difference between the battery module 012 and the battery module 002. Then, according to the rule of step C2, the second table is expressed as shown in Table 6 below:

[0137] Table 6

[0138]

[0139] It should be noted here that the battery performance difference described in step C2 is the absolute value of the difference between the third ratio of the above-mentioned simulated mixed object and the second ratio of the above-mentioned dependent unit. The larger the absolute value of the difference, the greater the difference between the two, otherwise the smaller it is.

[0140] C3, for the second element in the second list that has the same ranking as the first element in the first list, determine whether the number of element combinations that have an association relationship between the second element and the first element is at least "1",

[0141] If yes, extract the top-ranked element combination and mix and merge them as the mixed and merged battery group to power the electrical device next time;

[0142] If not, the proposed hybrid object ranked first in the first list is hybridized with the available balanced power source group with the maximum hybrid feasibility to form a hybrid battery group for the next power supply.

[0143] For example, the second element "009" in the second list expressed in Table 6 has the same ranking as the first element "x1" in the first list, and both are ranked first in the list, and the second element "012" has the same ranking as the first element "w1" in the first list, and both are ranked last in the list. In addition, the battery module 009 and the available balanced power group x1, as well as the battery module 012 and the available balanced power group w1 have been subjected to mixed feasibility calculations, indicating that there is an association relationship between 009 and x1, and there is an association relationship between 012 and w1. Then step C3 determines that the number of element combinations that have an association relationship with the first element is "2", and the element combination with the first ranking is extracted, that is, the battery module 009 and the available balanced power group x1 are used as the mixed battery group to power the electrical equipment next time.

[0144] Assuming that the number of element combinations is "0", the first-ranked simulated mixed object, that is, battery module 009, is extracted from the first list, and mixed with the available balanced power supply group (assuming it is x2) with the maximum mixing feasibility to form a mixed battery group that will power the electrical device next time.

[0145] After the above steps S1-S3, this embodiment can also quickly identify suspected faulty batteries by determining whether the number of times the same battery module is added to the dependent unit set is greater than a preset number threshold. If so, the battery module is determined to be a suspected faulty battery.

[0146] In addition, in this embodiment, the types of battery modules in the difference battery pack include any one or more of iron-lithium batteries, ternary lithium batteries, and sodium-ion batteries. After each power supply to the power-consuming equipment, the BMS controls each battery module in the difference battery pack to switch to a power-off isolation state, in order to obtain mixed data after predicting the power demand of the power-consuming equipment, so that it is possible to screen the mixed battery pack.

[0147] In summary, the BMS-based differential battery mixing method provided in the present application is a dynamic mixing method that takes power supply balance into consideration. Before each power supply to the electrical equipment, the number of times the battery module is used as the object of mixing is limited by searching for the object of mixing, so that each battery module is first balanced in the number of times used; then, by calculating the mixing effectiveness of the proposed balanced power group for the object of mixing, and the mixing acceptance of the proposed balanced power group by the proposed mixed object, the available balanced power group constructed for each proposed mixed object is conducive to reducing the internal resistance and power supply loss of the proposed mixed object, improving the rationality of the screening of available balanced power groups, and helping to reduce the overall power supply loss of the mixed battery group; by predicting the power demand of the electrical equipment, and taking the optimal mixing feasibility as the premise, through steps C1-C3, the optimal available balanced power group for the next power supply to the electrical equipment can be quickly identified among the multiple available balanced power groups that can be mixed by the same proposed mixed object, thereby reducing the power supply loss.

[0148] It should be noted that the above specific implementations are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art should understand that various modifications, equivalent substitutions, changes, etc. can be made to the present invention. However, as long as these changes do not deviate from the spirit of the present invention, they should be within the scope of protection of the present invention. In addition, some terms used in the specification and claims of this application are not restrictive, but are only for the convenience of description.

Claims

1. A method for mixing and merging different batteries based on BMS, characterized in that: After each power supply to the electrical equipment is completed, the BMS battery management system performs the following steps: S1, according to the historical power supply data of the difference battery group to the electrical equipment in the current charge and discharge cycle, by calculating the minimum feasibility of mixing and merging, to find the object to be mixed and merged in the difference battery group; S2, constructing an available balanced power group for each of the quasi-mixed objects, and adding the group to the available balanced power group set associated with each of the quasi-mixed objects; S3, according to the power demand prediction result of the power-consuming device, identifying the available balanced power group that will supply power to the power-consuming device next time from the set of available balanced power groups associated with each of the proposed mixed-and-merged objects, and then mixing and merging the proposed mixed-and-merged objects associated with the available balanced power groups to form a mixed-and-merged battery group that will supply power to the power-consuming device next time; After each power supply is completed, the BMS battery management system switches each battery module in the difference battery pack to a power-off isolation state; In step S1, one charge-discharge cycle is: during the interval between two consecutive constant current full charging operations on the difference battery pack, the charge-discharge process of the difference battery pack is one charge-discharge cycle; The method for finding the quasi-mixed object in the difference battery pack comprises the steps of: A1, obtaining a battery pack used to calculate the minimum hybrid feasibility; A2, calculating the minimum hybrid feasibility according to the historical hybrid data of the battery pack; A3, simulating an excitation source according to the historical hybrid data used to calculate the minimum hybrid feasibility, and then using the excitation source to separately charge and excite each of the remaining battery modules in the difference battery pack except the dependent unit in the basis battery pack, so as to obtain the available capacity change rate of each of the battery modules after the excitation; A4, determining whether the difference between the available capacity change rate of each battery module and the second ratio used to calculate the minimum hybrid feasibility is greater than a preset difference threshold, and if so, adding the battery module as the simulated hybrid object for supplying power to the electrical device next time to the simulated hybrid object set; The calculation in step A1 is based on the method for obtaining the battery pack, comprising the steps of: A11, select each battery module that is used as a historical mixing object at least twice from the difference battery group, and then construct a power loss list corresponding to each of the selected battery modules, and the construction method is: According to the historical mixing and merging sequence, the power loss of the historical mixed and merged battery group containing the battery module in supplying power to the electrical equipment is sorted to obtain the power loss list corresponding to each battery module; A12, for each of the battery modules, determine whether the power loss of each of the power loss lists associated with the battery module increases with the increase of the number of historical mixing times. If yes, the battery module is added to the dependent unit set for minimum hybrid feasibility calculation, and then the process goes to step A13; If not, determining that the battery module is a non-dependent unit for minimum hybrid feasibility calculation; A13, sorting the battery modules in the dependent unit set from large to small according to the number of historical mixing and merging times to form a sorted list, and then obtaining the historical mixed and merged battery group of the battery module ranked first in the sorted list at the last historical mixing and merging time as the basis battery group for calculating the minimum mixing and merging feasibility; In step A2, the historical mixing data based on the battery group used to calculate the minimum mixing feasibility includes: the first internal resistance change amount and the battery available capacity change amount of the dependent unit from the start of mixing to the battery terminal voltage balance between the dependent unit and the historical balanced power group in the battery group, the second internal resistance change amount of the historical balanced power group, the charging time of the dependent unit from the start of mixing to the battery terminal voltage balance, and the discharge current of each historical balanced power source in the historical balanced power group; In step A2, the minimum hybrid feasibility is: a weighted sum of a first ratio of the first internal resistance change to the second internal resistance change and a second ratio of the battery available capacity change of the dependent unit to the charging time; The second internal resistance change is a weighted sum of the internal resistance changes of the battery modules constituting the historical balanced power supply from the beginning of mixing to the time when the battery terminal voltage is balanced; In step S2, the method for constructing the available balanced power supply group for each of the pseudo-mixed objects comprises the following steps: B1, specifying the quasi-mixed object used to construct the proposed balanced power source group from the quasi-mixed object set; B2, randomly extracting the same number of battery modules as the historical balanced power sources in the historical balanced power source group in the battery group used to calculate the minimum mixed feasibility from the specified remaining set of the proposed mixed objects as the proposed balanced power sources; B3, connecting the extracted balanced power sources to be used in parallel to form a balanced power group to be used, and then mixing the balanced power group to be used with the object to be mixed and merged, and monitoring the mixed and merged data until each battery module in the balanced power group to be used reaches a battery terminal voltage balance state; B4, calculating the feasibility of mixing and merging the planned balanced power source group and the planned mixed and merged object according to the mixed and merged data; B5, judging whether the mixed-merge feasibility is greater than the minimum mixed-merge feasibility, If yes, determining that the proposed balanced power group is the available balanced power group available to the proposed mixed and merged object, and adding it to the available balanced power group set associated with the proposed mixed and merged object; If not, the process returns to step B2 to extract battery modules again to form different balanced power groups to be used, until it is no longer possible to form different balanced power groups to be used.

2. The method for mixing and merging different batteries based on BMS according to claim 1, characterized in that: The power loss is calculated by the following formula (1): In formula (1), The power supply loss of the historical mixed battery pack in supplying power to the electrical equipment; The first The change in available capacity of each battery module during power supply; Indicates the number of battery modules in the historical mixed battery pack; Indicates the amount of electricity consumed by the electrical equipment during the power supply period.

3. The method for mixing and merging different batteries based on BMS according to claim 1, characterized in that: In step A3, the excitation source includes a plurality of charging links corresponding to a historical balanced power source in the battery pack, each charging link having a charging current corresponding to the historical balanced power source for mixed charging of the dependent unit; each charging link excites each battery module with the same charging time as the historical balanced power source group in the battery pack for the dependent unit; after the charging excitation, the rate of change of the available capacity of the battery module is: a third ratio of the change in the available capacity of the battery module to the charging time.

4. The method for mixing and merging different batteries based on BMS according to claim 1, characterized in that: In step S3, the method of identifying the available balanced power group for supplying power to the electric device next time from the available balanced power group set associated with each of the objects to be mixed and merged comprises the following steps: C1, filtering out the available balanced power groups whose power supply is less than the predicted power demand in the sets of available balanced power groups respectively associated with the proposed mixed-merging objects, and then arranging the remaining available balanced power groups from high to low according to the mixed-merging feasibility with the associated proposed mixed-merging objects to form a first list; C2, calculating the difference between the battery performance of the pseudo-mixed objects associated with each of the available balanced power groups remaining after filtering in step C1 and the dependent units in the battery group, and arranging the pseudo-mixed objects from high to low according to the difference to form a second list; C3, for a second element in the second list having the same ranking as the first element in the first list, determining whether the number of element combinations having an association relationship between the second element and the first element is at least "1", If so, extract the element combination at the front of the sorting list, mix and merge them, and use them as the mixed and merged battery group for supplying power to the electrical device next time; If not, the proposed hybrid object ranked first in the first list is hybridized with the available balanced power source group with the maximum hybrid feasibility to form the hybrid battery group for the next power supply.

5. The method for mixing and merging different batteries based on BMS according to claim 1, characterized in that: Determine whether the number of times the same battery module is added to the dependent unit set is greater than a preset number threshold, and if so, determine that the battery module is a suspected faulty battery; The types of battery modules in the differential battery pack include any one or more of iron-lithium batteries, ternary lithium batteries, and sodium-ion batteries.

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