Battery assembly, its control method, drive system, controller and vehicle

Abstract

The present disclosure relates to the technical field of batteries, and in particular to a battery assembly, a control method thereof, a drive system, a controller, and a vehicle. The battery assembly includes a first battery unit and a second battery unit. The first battery unit includes at least one first battery cell monomer, and the second battery unit includes at least one second battery cell monomer. The second battery unit is disposed along the thickness direction of the first battery unit. The control method includes: controlling the cell states of the first battery cell monomer and the second battery cell monomer so that the cell expansion force of the battery assembly is within a preset cell expansion force range. Thus, by controlling the charge and discharge states of the first battery cell monomer and the second battery cell monomer, it is possible to make the increase in the thickness of the cells of one battery unit during charging match the decrease in the thickness of the cells of the other battery unit during discharging, so that the cell expansion force between the first battery unit and the second battery unit is within the preset cell expansion force range, thereby increasing the cycle life of the battery assembly.

Description

Technical Field

[0001] The present disclosure relates to the technical field of batteries, and in particular, to a battery assembly, a control method thereof, a drive system, a controller, and a vehicle. Background Art

[0002] The swelling force of an electrode cell refers to the force generated by the volume change of the electrode cell monomer in the battery assembly during charge and discharge due to internal chemical reactions, and generally includes the internal pressure of the electrode cell and the extrusion force between adjacent electrode cells. If the swelling force of the electrode cell is not effectively controlled, it will cause damage to the internal structure of the electrode cell monomer, such as diaphragm rupture or electrode material shedding, etc., thus affecting the cycle life of the battery assembly. Summary of the Invention

[0003] The purpose of the present disclosure is to provide a battery assembly, a control method thereof, a drive system, a controller, and a vehicle. By controlling the cell states of the first electrode cell monomer and the second electrode cell monomer, the swelling force of the battery assembly is made to be within a preset swelling force range, thereby improving the cycle life of the battery assembly.

[0004] To achieve the above purpose, in the first aspect of the present disclosure, a control method for a battery assembly is provided. The battery assembly includes a first battery unit and a second battery unit. The first battery unit includes at least one first electrode cell monomer, and the second battery unit includes at least one second electrode cell monomer. The second battery unit is disposed along the thickness direction of the first battery unit, and both the first electrode cell monomer and the second electrode cell monomer expand during charging and contract during discharging. The control method of the battery assembly includes:

[0005] Controlling the cell states of the first electrode cell monomer and the second electrode cell monomer so that the swelling force of the battery assembly is within a preset swelling force range, where the cell state includes a charging state, a discharging state, and an idle state.

[0006] Optionally, the controlling the cell states of the first electrode cell monomer and the second electrode cell monomer includes:

[0007] Obtaining the swelling force of the battery assembly;

[0008] Controlling the cell states of the first electrode cell monomer and the second electrode cell monomer according to the swelling force and the swelling force range.

[0009] Optionally, the swelling force range includes a first interval end value. The controlling the cell states of the first electrode cell monomer and the second electrode cell monomer according to the swelling force and the swelling force range includes:

[0010] When the swelling force of the battery cell is less than the endpoint value of the first interval, determine the first target battery cell with an idle state and the second target battery cell with a discharging state among the first battery cell unit and the second battery cell unit, maintain the discharging state of the second target battery cell, and control the state of the first target battery cell to change from the idle state to the charging state.

[0011] Optionally, the battery cell swelling force interval further includes a second interval endpoint value, and the second interval endpoint value is greater than the first interval endpoint value. It further includes:

[0012] When the swelling force of the battery cell is greater than the second interval endpoint value, determine the third target battery cell with a charging state and the fourth target battery cell with a discharging state among the first battery cell unit and the second battery cell unit, maintain the discharging state of the fourth target battery cell, and control the state of the third target battery cell to change from the charging state to the idle state.

[0013] Optionally, it further includes:

[0014] After controlling the state of the first target battery cell to change from the idle state to the charging state, obtain the first voltage of the first target battery cell and / or the second voltage of the second target battery cell;

[0015] When the first voltage is greater than or equal to the preset charging cut-off voltage, control the state of the first target battery cell to change from the charging state to the idle state; and / or

[0016] When the second voltage is less than or equal to the preset discharging cut-off voltage, control the state of the second target battery cell to change from the discharging state to the idle state or the charging state, and control the state of the first target battery cell to change from the charging state or the idle state to the discharging state.

[0017] Optionally, it further includes:

[0018] After controlling the state of the first target battery cell to change from the idle state to the charging state, obtain the first voltage and the ambient temperature, and determine the charging current of the first target battery cell according to the first voltage, the ambient temperature and a first preset relationship, and charge the first target battery cell based on the charging current, where the first preset relationship is used to represent the corresponding relationship among the ambient temperature, the battery cell unit voltage and the charging current.

[0019] Optionally, it further includes:

[0020] After controlling the cell state of the first target cell monomer to change from the charging state or the idle state to the discharging state, obtain the first voltage and the ambient temperature, and determine the discharging current of the first target cell monomer according to the first voltage, the ambient temperature, and a second preset relationship, where the second preset relationship is used to represent the corresponding relationship among the ambient temperature, the cell monomer voltage, and the discharging current, and perform discharging on the first target cell monomer based on the discharging current.

[0021] Optionally, the cell expansion force range is obtained by the following method:

[0022] Obtain a plurality of target acting forces, where the plurality of target acting forces are determined according to the influence degree of the acting forces applied to the battery assembly during the charge and discharge process on the life of the battery assembly;

[0023] Determine the first acting force with the largest acting force and the second acting force with the smallest acting force from the plurality of target acting forces, and determine the average acting force of the plurality of target acting forces;

[0024] Determine a first difference between the first acting force and the average acting force, and a second difference between the second acting force and the average acting force, and determine a correction value of the acting force according to the magnitudes of the first difference and the second difference;

[0025] Determine an acting force correction range according to the average acting force and the correction value, and use the acting force correction range as the cell expansion force range.

[0026] A second aspect of the present disclosure provides a battery assembly, where the battery assembly uses the method according to any one of the first aspect, and the battery assembly includes:

[0027] A first battery unit, the first battery unit includes at least one first cell monomer, and the first cell monomer expands during charging and contracts during discharging; and

[0028] A second battery unit, the second battery unit includes at least one second cell monomer, and the second cell monomer expands during charging and contracts during discharging, and the second battery unit is arranged along the thickness direction of the first battery unit.

[0029] Optionally, both the first battery unit and the second battery unit include a plurality, and the first battery unit and the second battery unit are arranged alternately, and the battery assembly further includes a first battery connecting piece and a second battery connecting piece, where a plurality of the first battery units are connected in series or in parallel through the first battery connecting piece, and a plurality of the second battery units are connected in series or in parallel through the second battery connecting piece.

[0030] Optionally, the cell type of the first cell unit may be the same as or different from that of the second cell unit.

[0031] Optionally, a detection component is further included, and at least one of the detection components is disposed on a target expansion surface of a target cell unit for detecting the cell expansion force of the battery component, where the target cell unit is a cell unit disposed at an edge position of the battery component, and the target expansion surface is an expansion surface of the target cell unit away from an adjacent cell unit.

[0032] A third aspect of the present disclosure provides a drive system, and the drive system includes the battery component according to any one of the second aspect.

[0033] A fourth aspect of the present disclosure provides a controller, and the controller includes:

[0034] A processor;

[0035] A memory for storing instructions executable by the processor;

[0036] Wherein, the processor is configured to execute the steps of the method according to any one of the first aspect.

[0037] A fifth aspect of the present disclosure provides a vehicle, including the battery component according to any one of the second aspect, the drive system according to the third aspect, or the controller according to the fourth aspect.

[0038] A sixth aspect of the present disclosure provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method according to any one of the first aspect are implemented.

[0039] A seventh aspect of the present disclosure provides a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the method according to any one of the first aspect are implemented.

[0040] Through the above technical solutions, by controlling the charging state and discharging state of the first cell unit in the first battery unit and the second cell unit in the second battery unit, it can be ensured that the increased thickness or expanded thickness of the first cell unit during charging matches the decreased thickness or shrunk thickness of the second cell unit during discharging in the second battery unit, or the shrunk thickness of the first cell unit during discharging matches the expanded thickness of the second cell unit during charging in the second battery unit, so that the cell expansion force between the first battery unit and the second battery unit is within a preset cell expansion force range, avoiding the influence of inappropriate cell expansion force on the cycle service life of the cell unit, and further increasing the cycle life of the cell.

[0041] Other features and advantages of the present disclosure will be described in detail in the following detailed description section. Description of the Drawings

[0042] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0043] Figure 1 is a schematic diagram of a battery assembly shown according to an exemplary embodiment of the present disclosure;

[0044] Figure 2 is a schematic diagram of another battery assembly shown according to an exemplary embodiment of the present disclosure;

[0045] Figure 3 is a schematic diagram of the installation position of a detection assembly in a battery assembly shown according to an exemplary embodiment of the present disclosure;

[0046] Figure 4 is a flowchart of a control method for a battery assembly shown according to an exemplary embodiment of the present disclosure;

[0047] Figure 5 is a flowchart of another control method for a battery assembly shown according to an exemplary embodiment of the present disclosure;

[0048] Figure 6 is a block diagram of a control device for a battery assembly shown according to an exemplary embodiment of the present disclosure;

[0049] Figure 7 is a schematic diagram of a drive system shown according to an exemplary embodiment of the present disclosure;

[0050] Figure 8 is a schematic diagram of a power battery system shown according to an exemplary embodiment of the present disclosure;

[0051] Figure 9 shows a schematic diagram of a drive system in the related art;

[0052] Figure 10 shows a schematic diagram of another drive system in the related art.

[0053] Description of the Reference Numerals

[0054] 1. First battery unit; 2. Second battery unit; 3. First battery connection piece; 4. Second battery connection piece; 5. Detection component; 6. First positive terminal; 7. First negative terminal; 8. First power output terminal; 9. First distribution box; 10. Second positive terminal; 11. Second negative terminal; 12. Second power output terminal; 13. Second distribution box; 14. First battery management system; 15. Second battery management system. Detailed implementation manners

[0055] The following will explain in detail the specific implementation manners of the present disclosure with reference to the accompanying drawings. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0056] In the present disclosure, unless otherwise stated, the orientation terms such as "upper" and "lower" are defined according to the actual arrangement state of the battery assembly, and the orientation terms such as "inner" and "outer" are defined for the contour of the corresponding component. The purpose of using terms such as "first" and "second" is to distinguish different components, and they do not have sequence and importance. In addition, in the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings represent the same or similar elements.

[0057] As described in the background art, the swelling force of the battery cell refers to the force generated by the volume change of the battery cell monomer in the battery assembly during charging and discharging due to internal chemical reactions, and generally can include the internal pressure of the battery cell and the extrusion force between adjacent battery cells. The cycle life of the battery cell is closely related to the swelling force of the battery cell. If the swelling force of the battery cell is not effectively controlled, it will cause damage to the internal structure of the battery cell monomer, such as diaphragm rupture or electrode material shedding, etc., thus affecting the cycle life of the battery cell monomer and the battery assembly.

[0058] Exemplarily, in a lithium-ion battery assembly, since the negative electrode of the battery cell is composed of graphite, during charging, lithium ions are embedded in the graphite, and at this time, the negative electrode becomes thicker due to the embedding of lithium ions, and externally, the outer shell of the battery cell becomes thicker in the swelling direction. During discharging, lithium ions are detached from the graphite of the negative electrode of the battery cell, and at this time, the negative electrode becomes thinner due to the detachment of lithium ions, and externally, the outer shell of the battery cell becomes thinner in the swelling direction. And since the battery cell monomer is generally arranged in the closed cavity of the battery pack, therefore, when the thickness of the battery cell increases, due to the constraint of the battery cell monomer in the battery pack, the swelling size will also be restricted, and the swelling force of the battery cell will increase. When the swelling force of the battery cell increases to a certain extent, lithium plating will occur during charging of the battery cell, resulting in a reduction in the cycle life of the battery cell.

[0059] To overcome the above technical problems, in related technologies, the swelling force of the battery cells is generally constrained by the fixed-distance method. That is, a certain distance is provided between battery cell monomers so that when the volume of the battery cell monomers changes, the swelling force of the battery cells will not be further increased due to the mutual extrusion of adjacent battery cell monomers. However, as the number of charge and discharge cycles of the battery cell monomers increases, the particles of the positive electrode material will be rearranged, resulting in an increase in thickness. At the same time, side reactions at the negative electrode will also form a thicker surface film. These changes will cause the overall thickness of the battery cell to increase and gradually fill the originally reserved swelling space. As the battery cell monomers continue to be cycled, the swelling force of the battery cells will gradually increase, and ultimately will still cause damage to the internal structure of the battery cell monomers, such as diaphragm rupture or electrode material detachment, etc., thereby affecting the cycle life of the battery cell monomers.

[0060] In view of this, embodiments of the present disclosure provide a battery assembly, a control method thereof, a drive system, a controller, and a vehicle to solve the above technical problems.

[0061] The following further explains embodiments of the present disclosure with reference to the accompanying drawings.

[0062] Figure 1 is a schematic diagram of a battery assembly shown according to an exemplary embodiment of the present disclosure. Referring to Figure 1 , the battery assembly may include a first battery unit 1 and a second battery unit 2. The first battery unit 1 includes at least one first battery cell monomer, and the second battery unit 2 includes at least one second battery cell monomer. The second battery unit 2 is arranged along the thickness direction of the first battery unit 1, and both the first battery cell monomer and the second battery cell monomer expand during charging and contract during discharging. Thus, by controlling the charging state and discharging state of the first battery cell monomer in the first battery unit 1 and the second battery cell monomer in the second battery unit 2, it can be made that the increased thickness or swelling thickness of the first battery cell monomer in the first battery unit 1 during charging matches the decreased thickness or contraction thickness of the second battery cell monomer in the second battery unit 2 during discharging, or the contraction thickness of the first battery cell monomer in the first battery unit 1 during discharging matches the swelling thickness of the second battery cell monomer in the second battery unit 2 during charging, so that the swelling force between the first battery unit 1 and the second battery unit 2 is within a preset swelling force range, avoiding the influence of inappropriate swelling force on the cycle service life of the battery cell monomers, and thus increasing the cycle life of the battery cells.

[0063] It should be understood that when a battery cell includes a plurality of single battery cells, in order to ensure the overall performance and safety of the battery cell, the states of the single battery cells in the battery cell are generally the same. Thus, when the first battery cell 1 includes a plurality of first single battery cells, controlling the state of the first single battery cell means synchronously controlling the states of all the first single battery cells in the first battery cell 1. For example, controlling the state of the first single battery cell to change from the charging state to the discharging state means controlling the states of all the first single battery cells in the first battery cell 1 to change from the charging state to the discharging state. Similarly, when the second battery cell 2 includes a plurality of second single battery cells, controlling the state of the second single battery cell means synchronously controlling the states of all the second single battery cells in the second battery cell 2. For example, controlling the state of the second single battery cell to change from the discharging state to the idle state means controlling the states of all the second single battery cells in the second battery cell 2 to change from the discharging state to the idle state.

[0064] It should be further understood that in this embodiment, the first battery cell 1 and the second battery cell 2 can be set to one or multiple. When the first battery cell 1 and the second battery cell 2 are set to multiple, the multiple first battery cells 1 can be connected in parallel or in series. Similarly, the multiple second battery cells 2 can be connected in parallel or in series. At the same time, in order to better match the expansion thickness and the contraction thickness of the single battery cell, so as to better control the expansion force of the battery cell in the battery assembly, and thus make the expansion force of the battery cell in the battery assembly fall within a preset expansion force range of the battery cell, the first battery cell 1 and the second battery cell 2 can be arranged alternately. That is to say, in a possible way, both the first battery cell 1 and the second battery cell 2 can include multiple, and the first battery cell 1 and the second battery cell 2 are arranged alternately. Correspondingly, the battery assembly can further include a first battery connection piece 3 and a second battery connection piece 4, wherein the multiple first battery cells 1 are connected in series or in parallel through the first battery connection piece 3, and the multiple second battery cells 2 are connected in series or in parallel through the second battery connection piece 4.

[0065] Exemplarily, the first battery cell 1 can include battery cells a1 - a20, and the second battery cell 2 can include battery cells b1 - b20. Thus, after the first battery cell 1 and the second battery cell 2 are arranged alternately, the arrangement order of the battery cells in the battery assembly can be: battery cell a1, battery cell b1, battery cell a2, battery cell b2, battery cell a3, battery cell b3,..., battery cell a20, battery cell b20, as Figure 2 shown. Among them, Figure 2The battery cells marked with black rectangles are battery cells a1 - a20, and the battery cells marked with black circles are battery cells b1 - b20. Correspondingly, when multiple first battery cells 1 are connected in parallel through the first battery connection piece 3, the first battery connection piece 3 may include a battery connection piece a1 and a battery connection piece a2. Among them, the battery connection piece a1 is respectively connected to the positive electrodes of the battery cells a1 - a20, and the battery connection piece a2 is respectively connected to the negative electrodes of the battery cells a1 - a20. When multiple first battery cells 1 are connected in series through the first battery connection piece 3, the first battery connection piece 3 may include battery connection pieces a3 - a19. Among them, the battery connection piece a3 is respectively connected to the positive electrode of the battery cell a1 and the negative electrode of the battery cell a2, the battery connection piece a4 is respectively connected to the positive electrode of the battery cell a2 and the negative electrode of the battery cell a3,..., and the battery connection piece a19 is respectively connected to the positive electrode of the battery cell a19 and the negative electrode of the battery cell a20.

[0066] Among them, the way that multiple second battery cells 2 are connected in series or in parallel through the second battery connection piece 4 refers to the way that multiple first battery cells 1 are connected in series or in parallel through the first battery connection piece 3, which will not be elaborated here.

[0067] Furthermore, in order to better match the expansion thickness and contraction thickness of the single battery cells, the number of the first single battery cells and the second single battery cells can be set to one or two, so that each first single battery cell can be adjacent to at least one second single battery cell, and further, the expansion thickness of the first single battery cell can be matched with the contraction thickness of the second single battery cell, or the contraction thickness of the first single battery cell can be matched with the expansion thickness of the second single battery cell.

[0068] Furthermore, the cell type of the first single battery cell and the cell type of the second single battery cell can be the same or different.

[0069] Exemplarily, when the cell type of the first single battery cell is the same as the cell type of the second single battery cell, the first single battery cell and the second single battery cell can both be lithium iron phosphate single battery cells, or can both be ternary single battery cells. Of course, it can also be others, and the embodiments of the present disclosure do not impose any restrictions on this.

[0070] When the cell type of the first single battery cell is different from the cell type of the second single battery cell, the first single battery cell can be a lithium iron phosphate single battery cell, and the second single battery cell can be a ternary single battery cell. Or the first single battery cell can be a sodium ion single battery cell, and the second single battery cell can be a lithium iron phosphate single battery cell. Of course, it can also be others, and the embodiments of the present disclosure do not impose any restrictions on this.

[0071] Further, in order to be able to detect the swelling force of the battery cells of the battery assembly, so that the swelling force of the battery cells of the battery assembly can be controlled to be within a preset battery cell swelling force range according to the detected swelling force of the battery cells, the battery assembly may further include a detection component 5, and at least one of the detection components 5 is disposed on the target swelling surface of the target battery cell for detecting the swelling force of the battery cells of the battery assembly, wherein the target battery cell is a battery cell disposed at the edge position of the battery assembly, and the target swelling surface is the swelling surface of the target battery cell away from the adjacent battery cells.

[0072] In this embodiment, the detection component 5 may be a pressure sensor, a displacement sensor, or others, and the embodiments of the present disclosure do not impose any restrictions thereon. When the detection component 5 is a pressure sensor, the pressure value detected by the pressure sensor can be directly determined as the swelling force of the battery cells of the battery assembly. When the detection component 5 is a displacement sensor, the product of the displacement value detected by the displacement sensor and the elastic modulus of the battery cell material can be calculated to obtain the swelling force of the battery cells of the battery assembly.

[0073] In this embodiment, the detection component 5 may include one or multiple. When there is one, the detection component 5 is disposed on the target swelling surface of the target battery cell, so that the detection component 5 can obtain the swelling force between all battery cells. When the detection component 5 includes multiple, one of the detection components 5 can be disposed on the target swelling surface of the target battery cell, and the other detection components 5 can be disposed at any position of the battery cell. On the one hand, more comprehensive swelling information of the battery cells can be obtained through the other detection components 5. On the other hand, when one of the detection components 5 fails, the other detection components 5 can be used to collect the swelling force of the battery cells, increasing the fault tolerance of the battery assembly. Exemplarily, as Figure 3 shown, the detection component 5 can be set as two pressure sensors, and the two pressure sensors are respectively disposed on the two end faces of the battery assembly. Thus, the pressure value collected by any one of the pressure sensors can be used as the swelling force of the battery cells, or the maximum pressure value collected by the two pressure sensors can be used as the swelling force of the battery cells, or the average value of the pressure values collected by the two pressure sensors can also be calculated and then used as the swelling force of the battery cells.

[0074] The control method of the battery assembly will be described below:

[0075] Figure 4 is a flowchart of a control method of a battery assembly shown according to an exemplary embodiment of the present disclosure. Referring to Figure 4 , the control method of the battery assembly may include the following steps:

[0076] 401: Control the cell states of the first cell unit and the second cell unit so that the cell expansion force of the battery assembly is within a preset cell expansion force range, where the cell states include a charging state, a discharging state, and an idle state.

[0077] As described above, in this embodiment, both the first cell unit and the second cell unit expand during charging and contract during discharging, that is, the cell thickness of the cell unit increases during charging and decreases during discharging. Thus, by controlling the charging state and discharging state of the first cell unit in the first battery unit 1 and the second cell unit in the second battery unit 2, it is possible to make the increased thickness or expansion thickness of the first cell unit in the first battery unit 1 during charging match the decreased thickness or contraction thickness of the second cell unit in the second battery unit 2 during discharging, or make the contraction thickness of the first cell unit in the first battery unit 1 during discharging match the expansion thickness of the second cell unit in the second battery unit 2 during charging, so that the cell expansion force between the first battery unit 1 and the second battery unit 2 is within a preset cell expansion force range, thereby avoiding the influence of inappropriate cell expansion force on the cycle service life of the cell unit, and further increasing the cycle life of the cell.

[0078] It should be understood that for different types of cell units, the corresponding cell expansion force ranges may be different. Therefore, the cell expansion force range can be determined according to the actual situation, and the embodiments of the present disclosure do not impose any restrictions on this. In a possible manner, the cell expansion force range can be obtained in the following way:

[0079] Obtain a plurality of target acting forces, where the plurality of target acting forces are determined according to the influence degree of the acting forces applied to the battery assembly during the charge and discharge process on the life of the battery assembly; from the plurality of target acting forces, determine the first acting force with the largest acting force and the second acting force with the smallest acting force, and determine the average acting force of the plurality of target acting forces; determine the first difference between the first acting force and the average acting force, and the second difference between the second acting force and the average acting force, and determine the correction value of the acting force according to the magnitudes of the first difference and the second difference; determine the acting force correction range according to the average acting force and the correction value, and use the acting force correction range as the cell expansion force range.

[0080] Exemplarily, a plurality of identical battery assemblies can be preset, and a fixed acting force is applied to each battery assembly, where the magnitudes of the fixed acting forces applied to each battery assembly are different. Then, when performing a cycle life test experiment on the battery assemblies with the fixed acting forces applied, the cycle life of each battery assembly is obtained, and the top N battery assemblies with the largest cycle life are selected therefrom according to the cycle life of each battery assembly. Thus, the fixed acting forces corresponding to the top N battery assemblies can be used as the target acting forces, where N is a positive integer.

[0081] After obtaining N target acting forces, the average acting force D of the N target acting forces can be calculated. After obtaining the average acting force D, the first acting force F1 with the largest acting force and the second acting force F2 with the smallest acting force are selected from the N target acting forces. Then, the difference between the first acting force F1 and the average acting force D is calculated to obtain the first difference d1, and the difference between the average acting force D and the second acting force F2 is calculated to obtain the second difference d2. If the first difference d1 is greater than the second difference d2, the second difference d2 is used as the correction value, and thus the acting force correction interval [D - d2, D + d2] can be obtained, that is, the cell expansion force interval is [D - d2, D + d2]. If the first difference d1 is less than the second difference d2, the second difference d1 is used as the correction value, and thus the acting force correction interval [D - d1, D + d1] can be obtained, that is, the cell expansion force interval is [D - d1, D + d1].

[0082] After obtaining the cell expansion force interval, the cell states of the first cell unit and the second cell unit can be controlled, so that the cell expansion force of the battery assembly is within the preset cell expansion force interval.

[0083] In a possible way, controlling the cell states of the first cell unit and the second cell unit may include:

[0084] Obtain the cell expansion force of the battery assembly; control the cell states of the first cell unit and the second cell unit according to the cell expansion force and the cell expansion force interval.

[0085] Exemplarily, a pressure sensor can be installed on the expansion surface of the battery assembly, so that the cell expansion force of the battery assembly can be collected through the pressure sensor. After collecting the cell expansion force, by judging whether the cell expansion force is within the cell expansion force interval, the cell states of the first cell unit and the second cell unit can be controlled to make the cell expansion force of the battery assembly within the cell expansion force interval.

[0086] In a possible way, the cell expansion force interval may include the first interval endpoint value. Correspondingly, controlling the cell states of the first cell unit and the second cell unit according to the cell expansion force and the cell expansion force interval may include:

[0087] When the cell expansion force is less than the first interval endpoint value, determine the first target cell unit with the cell state being the idle state and the second target cell unit with the cell state being the discharging state among the first cell unit and the second cell unit, keep the cell state of the second target cell unit as the discharging state, and control the cell state of the first target cell unit to change from the idle state to the charging state.

[0088] It should be understood that the charging speed of the battery cell is generally faster than the discharging speed of the battery cell, that is to say, the thickness increase speed of the first battery cell unit is faster than the thickness decrease speed of the second battery cell unit. Thus, when the swelling force of the battery cell is less than the first interval endpoint value, by changing the cell state of the first target battery cell unit from the idle state to the charging state, the swelling force of the battery module can be increased, so that the swelling force of the battery module is within the battery cell swelling force interval.

[0089] In a possible manner, the battery cell swelling force interval further includes a second interval endpoint value, and the second interval endpoint value is greater than the first interval endpoint value. Accordingly, according to the battery cell swelling force and the battery cell swelling force interval, controlling the cell states of the first battery cell unit and the second battery cell unit may further include:

[0090] When the battery cell swelling force is greater than the second interval endpoint value, determine a third target battery cell unit with a charging cell state and a fourth target battery cell unit with a discharging cell state among the first battery cell unit and the second battery cell unit, keep the cell state of the fourth target battery cell unit as the discharging state, and control the cell state of the third target battery cell unit to change from the charging state to the idle state.

[0091] As mentioned above, the charging speed of the battery cell is generally faster than the discharging speed of the battery cell, that is to say, the thickness increase speed of the first battery cell unit is faster than the thickness decrease speed of the second battery cell unit. Thus, when the battery cell swelling force is greater than the second interval endpoint value, by changing the cell state of the first target battery cell unit from the charging state to the idle state, the continuous increase in the thickness of the first battery cell unit can be avoided, so that the swelling force of the battery module is within the battery cell swelling force interval.

[0092] In a possible manner, it may further include:

[0093] After controlling the cell state of the first target battery cell unit to change from the idle state to the charging state, obtain the first voltage of the first target battery cell unit and / or the second voltage of the second target battery cell unit; when the first voltage is greater than or equal to the preset charging cut-off voltage, control the cell state of the first target battery cell unit to change from the charging state to the idle state; and / or, when the second voltage is less than or equal to the preset discharging cut-off voltage, control the cell state of the second target battery cell unit to change from the discharging state to the idle state or the charging state, and control the cell state of the first target battery cell unit to change from the charging state or the idle state to the discharging state.

[0094] It should be understood that, in order to prevent the single battery cell from being damaged or affecting its lifespan due to overcharging or over-discharging, a charging cut-off voltage and a discharging cut-off voltage are generally set for the single battery cell. Thus, after controlling the cell state of the first target single battery cell to change from the idle state to the charging state, the real-time voltage of the first target single battery cell can be obtained in real time, and when the real-time voltage of the first target single battery cell is greater than or equal to the preset charging cut-off voltage, the cell state of the first target single battery cell is controlled to change from the charging state to the idle state, thereby avoiding damage to the first target single battery cell or affecting its cycle life due to overcharging the first target single battery cell. Similarly, during the discharging process of the second target single battery cell, the real-time voltage of the second target single battery cell can also be obtained in real time, and when the real-time voltage of the second target single battery cell is less than or equal to the preset discharging cut-off voltage, the cell state of the second target single battery cell is controlled to change from the discharging state to the idle state or the charging state, and the cell state of the first target single battery cell is controlled to change from the charging state or the idle state to the discharging state. On the one hand, this can avoid damage to the second target single battery cell or affecting its cycle life due to over-discharging the second target single battery cell, and on the other hand, it can also maintain the working state of the battery unchanged.

[0095] In addition, it should be understood that when the battery unit includes multiple single battery cells, in order to ensure the overall performance and safety of the battery unit, the electrical performance parameters of the multiple single battery cells in the battery unit, such as voltage, charging cut-off voltage, discharging cut-off voltage, charging current, and / or discharging current, etc., are generally the same. Thus, obtaining the first voltage of the first target single battery cell can be obtaining the first voltage of any one of the first target single battery cells, or of course, it can also be obtaining the average value of the voltages of multiple first target single battery cells. The embodiments of the present disclosure do not impose any restrictions on this. Similarly, obtaining the second voltage of the second target single battery cell can be obtaining the second voltage of any one of the second target single battery cells, or obtaining the average value of the voltages of multiple second target single battery cells.

[0096] In a possible way, it may further include:

[0097] After controlling the cell state of the first target single battery cell to change from the idle state to the charging state, obtain the first voltage and the ambient temperature, and determine the charging current of the first target single battery cell according to the first voltage, the ambient temperature, and a first preset relationship, where the first preset relationship is used to represent the corresponding relationship among the ambient temperature, the single battery cell voltage, and the charging current, and charge the first target single battery cell based on the charging current.

[0098] It should be understood that when the single battery cell is charged too quickly, that is, when the charging current is greater than the preset charging current threshold, lithium plating will occur inside the single battery cell. After lithium plating, the single battery cell will accelerate the capacity decay of the battery cell, and further accelerate the decay of the cycle life. In addition, since the charging current thresholds corresponding to the single battery cell are generally different under different ambient temperatures and different single battery cell voltages, therefore, to avoid excessive charging current and affect the cycle life of the single battery cell, in this embodiment, the corresponding relationship between the ambient temperature, the single battery cell voltage, and the charging current is preset, so that when charging the single battery cell, the charging current of the single battery cell can be determined according to the real-time voltage of the single battery cell, the real-time ambient temperature where the single battery cell is located, and the corresponding relationship, thereby further improving the cycle life of the battery.

[0099] In this embodiment, the charging current corresponding to the first preset relationship can be the maximum charging current of the single battery cell, or can be a current less than the maximum charging current determined based on the maximum charging current and the current correction value. Of course, it can also be other, and the embodiments of the present disclosure do not make any restrictions on this. When the charging current corresponding to the first preset relationship is the maximum charging current of the single battery cell, the charging current corresponding to the first preset relationship can be determined based on the lithium plating experiment.

[0100] Exemplarily, at temperature T, a force in the range of [D - d1, D + d1] can be applied to N single battery cells with an initial voltage of V1, and the N single battery cells are charged with different current magnitudes, and the current magnitudes increase in sequence. When the voltage of the single battery cell changes to V2, disassemble the single battery cell to check whether lithium plating occurs in the single battery cell under the above current, and determine the maximum charging current corresponding to the single battery cell without lithium plating as the charging current corresponding to temperature T and voltage V1. Repeat the above process to obtain the corresponding relationship between the ambient temperature, the single battery cell voltage, and the charging current.

[0101] In a possible way, it may further include:

[0102] After controlling the battery cell state of the first target single battery cell to change from the charging state or the idle state to the discharging state, obtain the first voltage and the ambient temperature, and determine the discharging current of the first target single battery cell according to the first voltage, the ambient temperature, and the second preset relationship, and discharge the first target single battery cell based on the discharging current, where the second preset relationship is used to represent the corresponding relationship between the ambient temperature, the single battery cell voltage, and the discharging current.

[0103] It should be understood that when the single battery cell discharges too quickly, that is, when the discharge current is greater than the preset discharge current threshold, it will cause the ions on the electrode surface to quickly de-embed or embed, resulting in a large local current density. This rapid ion migration may cause an increase in the stress of the electrode material, leading to particle breakage or structural deformation of the electrode material, thereby damaging the active material interface. After the loss of the active material interface, if the single battery cell is charged, ions may not be able to normally embed into the negative electrode material but deposit on the surface of the negative electrode, thereby affecting the cycle life of the single battery cell. In addition, since the discharge current thresholds corresponding to the single battery cell are generally different under different ambient temperatures and different single battery cell voltages, thus, to avoid excessive discharge current and affect the cycle life of the single battery cell, in this embodiment, by presetting the corresponding relationship between the ambient temperature, the single battery cell voltage, and the discharge current, when discharging the single battery cell, the discharge current of the single battery cell can be determined according to the real-time voltage of the single battery cell, the real-time ambient temperature where the single battery cell is located, and the corresponding relationship, thereby further improving the cycle life of the battery.

[0104] In this embodiment, the discharge current corresponding to the second preset relationship can be the maximum discharge current of the single battery cell, or a current less than the maximum discharge current determined based on the maximum discharge current and the current correction value. Of course, it can also be other, and the embodiments of the present disclosure do not make any restrictions on this. When the discharge current corresponding to the second preset relationship is the maximum discharge current of the single battery cell, the discharge current corresponding to the second preset relationship can be determined based on the lithium plating experiment.

[0105] Exemplarily, at temperature T, a force in the range of [D - d1, D + d1] can be applied to N single battery cells with an initial voltage of V3, and the N single battery cells are discharged with different current magnitudes, and the current magnitudes increase in sequence. When the voltage of the single battery cell changes to V4, the N single battery cells are then charged with different current magnitudes, and the current magnitudes increase in sequence. When the voltage of the single battery cell changes to V4, the single battery cell is disassembled to check whether lithium plating occurs in the above N single battery cells, and the maximum discharge current corresponding to the single battery cell without lithium plating is determined as the discharge current corresponding to temperature T and voltage V3. Repeat the above process to obtain the corresponding relationship characterizing the ambient temperature, the single battery cell voltage, and the discharge current.

[0106] To facilitate understanding of the control method of the battery assembly provided by the present disclosure, a possible implementation manner of the present disclosure is described below:

[0107] Exemplarily, such as Figure 5As shown, when controlling the discharge of the first battery cell in the battery assembly, first obtain the ambient temperature and the real-time voltage of the first battery cell, and determine the discharge current of the first battery cell according to the ambient temperature, the real-time voltage of the first battery cell, and the second preset relationship. Then, control the first battery cell to discharge based on this discharge current. After that, on the one hand, the expansion force of the battery cells in the battery assembly is detected in real time by a pressure sensor, and it is determined whether the expansion force F of the battery cells is less than the first interval endpoint value D - d. On the other hand, the real-time voltage of the first battery cell is detected in real time, and it is determined whether the real-time voltage Va of the first battery cell is greater than the discharge cut-off voltage V1. When the real-time voltage Va of the first battery cell is greater than the discharge cut-off voltage V1, if the expansion force F of the battery cells is less than the first interval endpoint value D - d, then obtain the ambient temperature and the real-time voltage of the second battery cell, and determine the charging current of the second battery cell according to the ambient temperature, the real-time voltage of the second battery cell, and the first preset relationship. Then, control the first battery cell to charge based on this charging current. After that, on the one hand, the real-time voltage Vb of the second battery cell is detected in real time, and it is determined whether the real-time voltage Vb of the second battery cell is greater than the charging cut-off voltage V2. On the other hand, the expansion force of the battery cells in the battery assembly is detected in real time by a pressure sensor, and it is determined whether the expansion force F of the battery cells is greater than the second interval endpoint value D + d. When the real-time voltage Vb of the second battery cell is greater than the charging cut-off voltage V2, or when it is detected that the expansion force F of the battery cells is greater than the second interval endpoint value D + d, stop charging the second battery cell. When the real-time voltage Va of the first battery cell is less than the discharge cut-off voltage V1, on the one hand, stop discharging the first battery cell, and on the other hand, obtain the ambient temperature and the real-time voltage of the second battery cell, and determine the discharge current of the second battery cell according to the ambient temperature, the real-time voltage of the second battery cell, and the second preset relationship. Then, control the second battery cell to discharge based on this discharge current.

[0108] Based on the same concept, an embodiment of the present disclosure further provides a control device for a battery assembly. The battery assembly includes a first battery unit 1 and a second battery unit 2. The first battery unit 1 includes at least one first battery cell, and the second battery unit 2 includes at least one second battery cell. The second battery unit 2 is arranged along the thickness direction of the first battery unit 1, and both the first battery cell and the second battery cell expand during charging and contract during discharging. Correspondingly, the control device for the battery assembly can be as Figure 6 shown, including:

[0109] A control module 601, configured to control the cell states of the first battery cell and the second battery cell so that the expansion force of the battery cells in the battery assembly is within a preset expansion force interval of the battery cells, where the cell states include a charging state, a discharging state, and an idle state.

[0110] In a possible way, the control module 601 may include:

[0111] A first acquisition unit, configured to acquire the swelling force of the battery cells of the battery assembly;

[0112] A first control unit, configured to control the cell states of the first cell unit and the second cell unit according to the swelling force of the battery cells and the swelling force range.

[0113] In a possible manner, the swelling force range includes a first range end value. Correspondingly, the first control unit is configured to, when the swelling force of the battery cells is less than the first range end value, determine, among the first cell unit and the second cell unit, a first target cell unit with a cell state of idle state and a second target cell unit with a cell state of discharging state, maintain the cell state of the second target cell unit as the discharging state, and control the cell state of the first target cell unit to change from the idle state to the charging state.

[0114] In a possible manner, the swelling force range further includes a second range end value, and the second range end value is greater than the first range end value. Correspondingly, the first control unit is further configured to, when the swelling force of the battery cells is greater than the second range end value, determine, among the first cell unit and the second cell unit, a third target cell unit with a cell state of charging state and a fourth target cell unit with a cell state of discharging state, maintain the cell state of the fourth target cell unit as the discharging state, and control the cell state of the third target cell unit to change from the charging state to the idle state.

[0115] In a possible manner, the control module 601 may further include:

[0116] A second acquisition unit, configured to acquire the first voltage of the first target cell unit and / or the second voltage of the second target cell unit after controlling the cell state of the first target cell unit to change from the idle state to the charging state;

[0117] A second control unit, configured to control the cell state of the first target cell unit to change from the charging state to the idle state when the first voltage is greater than or equal to a preset charging cut-off voltage; and / or

[0118] A third control unit, configured to control the cell state of the second target cell unit to change from the discharging state to the idle state or the charging state, and control the cell state of the first target cell unit to change from the charging state or the idle state to the discharging state when the second voltage is less than or equal to a preset discharging cut-off voltage.

[0119] In a possible manner, the control module 601 may further include:

[0120] A fourth control unit is configured to, after controlling the cell state of the first target cell monomer to change from the idle state to the charging state, obtain a first voltage and an ambient temperature, and determine a charging current of the first target cell monomer according to the first voltage, the ambient temperature, and a first preset relationship, and charge the first target cell monomer based on the charging current, where the first preset relationship is used to represent the corresponding relationship among the ambient temperature, the cell monomer voltage, and the charging current.

[0121] In a possible manner, the control module 601 may further include:

[0122] A fourth control unit is configured to, after controlling the cell state of the first target cell monomer to change from the charging state or the idle state to the discharging state, obtain a first voltage and an ambient temperature, and determine a discharging current of the first target cell monomer according to the first voltage, the ambient temperature, and a second preset relationship, and discharge the first target cell monomer based on the discharging current, where the second preset relationship is used to represent the corresponding relationship among the ambient temperature, the cell monomer voltage, and the discharging current.

[0123] In a possible manner, the cell expansion force range is obtained in the following way:

[0124] Obtain a plurality of target acting forces, where the plurality of target acting forces are determined according to the influence degree of the acting forces applied to the battery assembly during the charge and discharge process on the life of the battery assembly;

[0125] Determine a first acting force with the largest acting force and a second acting force with the smallest acting force from the plurality of target acting forces, and determine the average acting force of the plurality of target acting forces;

[0126] Determine a first difference between the first acting force and the average acting force, and a second difference between the second acting force and the average acting force, and determine a correction value of the acting force according to the magnitudes of the first difference and the second difference;

[0127] Determine an acting force correction range according to the average acting force and the correction value, and use the acting force correction range as the cell expansion force range.

[0128] Regarding the control device 600 of the battery assembly in the above embodiments, the specific manners in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0129] Based on the same concept, an embodiment of the present disclosure further provides a drive system, and the drive system may include the battery assembly of any one of the above.

[0130] Exemplarily, the drive system may be as Figure 7As shown, it includes a range extender system, an electronic control system, an electric motor drive system, and a power battery system. Among them, the power battery system can be as Figure 8 shown, including a battery assembly, a first battery management system 14 (Battery Management System, BMS), a second battery management system 15, a first distribution box 9, and a second distribution box 13. Among them, the battery assembly includes a plurality of first battery cells 1, a plurality of second battery cells 2, and two detection components 5, denoted as the first detection component and the second detection component. After a plurality of first battery cells 1 are connected in series through a first battery connection piece 3, a first positive terminal 6, a first negative terminal, and a first power output terminal 8 are formed. The first power output terminal 8 is connected to the electronic control system, and both the first positive terminal 6 and the first negative terminal 7 are connected to the first distribution box 9. After a plurality of second battery cells 2 are connected in series through a second battery connection piece 4, a second positive terminal 10, a second negative terminal 11, and a second power output terminal 12 are formed. The second power output terminal 12 is connected to the electronic control system, and both the second positive terminal 10 and the second negative terminal 11 are connected to the second distribution box 13. The first detection component 5 is arranged on the left end face of the battery assembly and is connected to the first battery management system 14. The second detection component 5 is arranged on the right end face of the battery assembly and is connected to the second battery management system 15. The range extender system can include an engine and a generator. Among them, both the engine and the generator are connected to the electronic control system, and the electronic control system is respectively connected to the electric motor drive system and the power battery system. Thus, during the vehicle driving process, the first battery cell in the first battery unit 1 in the power battery system can provide electric energy to the electric drive system through the electronic control system, thereby driving the vehicle to travel. As the first battery cell discharges, the thickness of the first battery cell will decrease, resulting in a gradual decrease in the cell expansion force. When the detection components 5 arranged on both sides of the battery assembly detect that the cell expansion force is less than the first interval endpoint value D - d, the electronic control system commands the range extender system to charge the second battery cell in the second battery unit 2. When it is detected that the cell expansion force is greater than the second interval endpoint value D + d, or when it is detected that the real-time voltage of the second battery cell reaches the charging cut-off voltage, the charging of the second battery cell is stopped. When the first battery cell reaches the discharge cut-off voltage, the first battery cell is controlled to stop discharging externally, and the second battery cell that has been fully charged discharges externally. Similarly, as the second battery cell discharges, the thickness of the second battery cell will decrease, resulting in a gradual decrease in the cell expansion force. When the detection component 5 detects that the cell expansion force is less than the first interval endpoint value D - d, the electronic control system commands the range extender system to charge the first battery cell in the first battery unit 1. When the cell expansion force is greater than D + d or reaches the charging cut-off voltage, the first battery cell is controlled to stop charging. This process is repeated to ensure that the cell expansion force of the battery assembly is always within the preset range, thereby improving the cycle life of the battery assembly.

[0131] It should be understood that in the drive system in the related art, in order to improve the endurance, a main battery pack and an extended-range battery pack are generally provided. By way of example, as Figure 9 and Figure 10 shown, the drive system may include two battery packs, one is a traditional main battery pack, and the other is an extended-range battery pack that can be replaced with electricity, so that when the main battery pack has insufficient power, the extended-range battery pack can charge the main battery pack and supply power to the main motor; when the extended-range battery pack has insufficient power, the energy of the extended-range battery pack can be quickly replenished by replacing the extended-range battery pack.

[0132] In this kind of drive system, since traditional battery components are used, that is, there is no obvious constraint on the expansion force of the battery cells, there is a problem of low battery cycle life. In addition, since when the main battery pack is in a low-power state, the extended-range battery pack needs to charge the main battery pack on the one hand and drive the whole vehicle on the other hand, there will be a situation where the acceleration and climbing kinetic energy are insufficient. In addition, since the extended-range battery pack needs to be disassembled, on the one hand, the design of the extended-range battery pack is more complicated, and handles, slots, fixing brackets, sliding devices, etc. need to be designed, which increases the cost of the whole vehicle; on the other hand, non-professionals manually install the extended-range battery pack, which is easy to be installed in place, thus there is a problem of potential safety hazards.

[0133] In the drive system of this embodiment, since the expansion force of the battery cells of the battery assembly can be restricted by controlling the charge and discharge states of the first battery cell and the second battery cell, the expansion force of the battery cells can always be within a preset expansion force range of the battery cells, thereby improving the cycle life of the battery. In addition, in the drive system of this embodiment, the endurance is not achieved by the extended-range battery pack, but by the extended-range generator system. That is, when the battery pack has insufficient power, on the one hand, the extended-range generator system can burn fuel to complete the endurance, and on the other hand, the extended-range generator system can also burn fuel to supplement electric energy for the battery pack. Therefore, there are no problems such as insufficient power, high cost of the whole vehicle, and potential safety hazards. In addition, since the battery pack in this embodiment includes the first battery cell and the second battery cell that can work independently, in complex working conditions, such as sudden acceleration or climbing, the first battery cell and the second battery cell can be controlled to supply power to the motor drive system through the electronic control system at the same time for a short time, or the extended-range generator, the first battery cell and the second battery cell can supply power to the motor drive system through the electronic control system at the same time to achieve an ideal acceleration ability, etc.

[0134] Based on the same concept, an embodiment of the present disclosure further provides a controller, which includes:

[0135] a processor;

[0136] a memory for storing instructions executable by the processor;

[0137] Wherein, the processor is configured to: execute the steps of the above-mentioned control method of the battery assembly.

[0138] Based on the same concept, an embodiment of the present disclosure further provides a vehicle, including the battery assembly of any one of the above, the drive system of the above, or the controller of the above.

[0139] Based on the same concept, an embodiment of the present disclosure further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the above-mentioned control method of the battery assembly.

[0140] Based on the same concept, an embodiment of the present disclosure further provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the steps of the above-mentioned control method of the battery assembly.

[0141] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0142] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, without conflict, they can be combined in any appropriate manner. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0143] In addition, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A method for controlling a battery assembly, characterized in that: The battery assembly includes a first battery unit and a second battery unit, the first battery unit includes at least one first battery cell, the second battery unit includes at least one second battery cell, the second battery unit is arranged along the thickness direction of the first battery unit, and the first battery cell and the second battery cell both expand during charging and shrink during discharging, and the control method of the battery assembly includes: According to the cell expansion force of the battery assembly and a preset cell expansion force range, the cell states of the first cell monomer and the second cell monomer are controlled so that the cell expansion force of the battery assembly is located in the cell expansion force range, wherein the cell states of the first cell monomer and the second cell monomer are different, and the cell states include a charging state, a discharging state and an idle state, and the cell expansion force of the battery assembly is suitable for being determined by a detection component arranged on an end face of the battery assembly and used to detect the cell expansion force of the battery assembly.

2. The control method of the battery assembly according to claim 1, characterized in that: The battery cell expansion force interval includes a first interval endpoint value, and controlling the battery cell states of the first battery cell monomer and the second battery cell monomer according to the battery cell expansion force and the battery cell expansion force interval includes: When the cell expansion force is less than the first interval endpoint value, determine a first target cell whose cell state is an idle state and a second target cell whose cell state is a discharged state among the first cell and the second cell, keep the cell state of the second target cell in the discharged state, and control the cell state of the first target cell to change from an idle state to a charged state.

3. The control method of the battery assembly according to claim 2, characterized in that: The cell expansion force interval also includes a second interval endpoint value, and the second interval endpoint value is greater than the first interval endpoint value, and further includes: When the cell expansion force is greater than the endpoint value of the second interval, determine that among the first cell and the second cell, a third target cell whose cell state is a charging state and a fourth target cell whose cell state is a discharging state, keep the cell state of the fourth target cell in a discharging state, and control the cell state of the third target cell to change from a charging state to an idle state.

4. The control method of the battery assembly according to claim 2, characterized in that: Also includes: After controlling the cell state of the first target cell to change from an idle state to a charging state, obtaining a first voltage of the first target cell and / or a second voltage of the second target cell; When the first voltage is greater than or equal to a preset charge cut-off voltage, controlling the cell state of the first target cell monomer to change from a charging state to an idle state; and / or When the second voltage is less than or equal to the preset discharge cut-off voltage, the cell state of the second target cell is controlled to change from the discharge state to the idle state or the charge state, and the cell state of the first target cell is controlled to change from the charge state or the idle state to the discharge state.

5. The control method of the battery assembly according to claim 4, characterized in that: Also includes: After controlling the cell state of the first target battery cell to change from an idle state to a charging state, the first voltage and ambient temperature are obtained, and the charging current of the first target battery cell is determined according to the first voltage, the ambient temperature and a first preset relationship, and the first target battery cell is charged based on the charging current, wherein the first preset relationship is used to characterize the correspondence between the ambient temperature, the battery cell voltage and the charging current.

6. The control method of the battery assembly according to claim 4, characterized in that: Also includes: After controlling the cell state of the first target battery cell to change from a charging state or an idle state to a discharging state, the first voltage and the ambient temperature are obtained, and the discharge current of the first target battery cell is determined according to the first voltage, the ambient temperature and a second preset relationship, and the first target battery cell is discharged based on the discharge current, wherein the second preset relationship is used to characterize the correspondence between the ambient temperature, the battery cell voltage and the discharge current.

7. The control method of the battery assembly according to any one of claims 1 to 6, characterized in that: The cell expansion force range is obtained by: Acquire a plurality of target forces, wherein the plurality of target forces are determined according to the influence of the force applied to the battery assembly during the charging and discharging process of the battery assembly on the life of the battery assembly; Determine a first force with the largest force and a second force with the smallest force from the multiple target forces, and determine an average force of the multiple target forces; Determine a first difference between the first force and the average force, and a second difference between the second force and the average force, and determine a correction value of the force according to the magnitude of the first difference and the second difference; A force correction interval is determined according to the average force and the correction value, and the force correction interval is used as the battery cell expansion force interval.

8. A battery assembly, characterized in that: The battery assembly uses the control method of the battery assembly according to any one of claims 1 to 7, and the battery assembly comprises: a first battery unit, the first battery unit comprising at least one first battery cell, the first battery cell expanding during charging and shrinking during discharging; and The second battery unit includes at least one second battery cell, the second battery cell expands during charging and contracts during discharging, and the second battery unit is arranged along the thickness direction of the first battery unit.

9. The battery assembly according to claim 8, characterized in that: The first battery cells and the second battery cells each include a plurality, and the first battery cells and the second battery cells are alternately arranged, and the battery assembly also includes a first battery connecting plate and a second battery connecting plate, wherein the plurality of the first battery cells are connected in series or in parallel through the first battery connecting plate, and the plurality of the second battery cells are connected in series or in parallel through the second battery connecting plate.

10. The battery assembly according to claim 8 or 9, characterized in that: The cell type of the first cell monomer is the same as or different from the cell type of the second cell monomer.

11. The battery assembly according to claim 8 or 9, characterized in that: It also includes detection components, at least one of which is arranged on the target expansion surface of the target battery cell to detect the battery cell expansion force of the battery assembly, wherein the target battery cell is a battery cell arranged at the edge of the battery assembly, and the target expansion surface is the expansion surface of the target battery cell away from the adjacent battery cell.

12. A drive system, characterized in that: The driving system comprises the battery assembly according to any one of claims 8-11.

13. A controller, characterized in that: The controller comprises: processor; a memory for storing processor-executable instructions; The processor is configured to: execute the steps of the method described in any one of claims 1-7.

14. A vehicle, characterized in that: It comprises the battery assembly described in any one of claims 8 to 11, the drive system described in claim 12 or the controller described in claim 13.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

16. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1 to 7.

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