Active adjustable equalization battery and equalization method

Abstract

The invention provides an active adjustable equalization battery and an equalization method, and belongs to the technical field of battery management. Comprising a plurality of battery cells which are stacked in sequence, and positive electrodes and negative electrodes which are arranged at intervals are arranged on the end surfaces of the battery cells; the conversion circuit is provided with a plurality of first connection point positions and a plurality of second connection point positions which are arranged in pairs, the plurality of first connection point positions are electrically connected with the positive electrodes of the plurality of battery cells in a one-to-one correspondence manner, and the plurality of second connection point positions are electrically connected with the negative electrodes of the plurality of battery cells in a one-to-one correspondence manner; the conversion circuit is also electrically connected with the positive bus and the negative bus; the BMS is electrically connected with the plurality of battery cells and the conversion circuit and is used for acquiring single voltage of the plurality of battery cells; and the BMS also changes the switching circuit to switch the connection state of the first connection point and the second connection point of the adjacent battery cells, so that the series charging and discharging of the plurality of battery cells, the parallel charging and discharging of the plurality of battery cells, or the charging and discharging of a single battery cell are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery balancing, and particularly to an active adjustable balancing battery and a balancing method. Background Art

[0002] Lithium batteries often have undetectable defects during the production process and consistency problems during production, which are manifested as large voltage differences during later use. After the battery voltage difference is too large, it is often easy to cause a decrease in available capacity and energy efficiency, and in severe cases, it will cause safety problems. Currently, the battery is mainly monitored by setting the voltage difference threshold under different battery states, and after the voltage difference exceeds the threshold, it is adjusted by manual charging. However, this method requires personnel participation and a long construction period, and it is very troublesome to maintain.

[0003] Therefore, it is very necessary to provide an active adjustable balancing battery and a balancing method to improve the problem of inconvenient cell maintenance by introducing an integrated adjustable charging circuit. Summary of the Invention

[0004] In view of this, the present invention proposes an active adjustable balancing battery and a balancing method that can dynamically adjust the charging strategy, isolate abnormal cells, dynamically adjust the charging state of each cell, and achieve active adjustable balancing.

[0005] On the one hand, the present invention provides an active adjustable balancing battery, including:

[0006] A plurality of cells are stacked in sequence, and both end faces of the plurality of cells include a positive electrode and a negative electrode arranged at intervals;

[0007] A conversion circuit is provided with a plurality of first connection points and a plurality of second connection points arranged in pairs. The plurality of first connection points are electrically connected to the positive electrodes of the plurality of cells in one-to-one correspondence, and the plurality of second connection points are electrically connected to the negative electrodes of the plurality of cells in one-to-one correspondence; the conversion circuit is also electrically connected to the positive bus bar and the negative bus bar;

[0008] A BMS is electrically connected to the plurality of cells and the conversion circuit respectively to obtain the single-cell voltages of the plurality of cells;

[0009] Wherein, the BMS also changes the connection state of the first connection point and the second connection point of the conversion circuit to switch adjacent cells, so as to achieve series charge and discharge of the plurality of cells, parallel charge and discharge of the plurality of cells, or charge and discharge of a single cell.

[0010] Based on the above technical solutions, preferably, the conversion circuit further includes a plurality of first switching units and a plurality of second switching units. The first switching units are arranged between adjacent first connection points, and the second switching units are arranged between adjacent second connection points; one end of the first switching unit is electrically connected to the first connection point corresponding to the current battery cell, and one end of the second switching unit is electrically connected to the second connection point corresponding to the battery cell adjacent to the current battery cell. The other end of the first switching unit is rotatable relative to the first connection point, and the other end of the second switching unit is rotatable relative to the second connection point.

[0011] Preferably, the number of both the first switching units and the second switching units is N; the first switching unit includes a first connecting piece and a second connecting piece; for the k-th first switching unit, k = 1, 2,..., N, one end of the first connecting piece is fixedly connected to the k-th first connection point, and the other end of the first connecting piece is hinged to one end of the second connecting piece;

[0012] The second switching unit includes a third connecting piece and a fourth connecting piece; for the k-th second switching unit, one end of the third connecting piece is fixedly connected to the (k + 1)-th second connection point, and the other end of the third connecting piece is hinged to one end of the fourth connecting piece;

[0013] The second connecting piece rotates towards the (k + 1)-th first connection point and abuts against it, and the fourth connecting piece rotates towards the k-th second connection point and abuts against it, to achieve the parallel connection of adjacent battery cells; the second connecting piece rotates towards the direction of the (k + 1)-th second connection point, and the fourth connecting piece rotates towards the k-th first connection point, to achieve the series connection of adjacent battery cells.

[0014] Further preferably, a current-limiting resistor is also arranged on the second connecting piece.

[0015] Further preferably, the first switching units and the second switching units are microswitches or toggle switches.

[0016] On the other hand, the present invention also provides an equalization method for an active adjustable equalization battery, including the following steps:

[0017] S1: Configure an active adjustable equalization battery as described above; where the number of battery cells is N + 1, and the battery cells are stacked in sequence in the width direction; the conversion circuit has N pairs of first connection points and a plurality of second connection points. The first connection points are electrically connected to the positive electrodes of the respective battery cells one by one, the second connection points are electrically connected to the negative electrodes of the respective battery cells one by one, the (N + 1)-th first connection point is electrically connected to the positive bus, and the first second connection point is electrically connected to the negative bus;

[0018] The conversion circuit further includes a plurality of first switching units and a plurality of second switching units; the first switching unit includes a first connecting piece and a second connecting piece; for the k-th first switching unit, k = 1, 2, …, N, one end of the first connecting piece is fixedly connected to the k-th first connection point position, and the other end of the first connecting piece is hinged to one end of the second connecting piece; the second switching unit includes a third connecting piece and a fourth connecting piece; for the k-th second switching unit, one end of the third connecting piece is fixedly connected to the (k + 1)-th second connection point position, and the other end of the third connecting piece is hinged to one end of the fourth connecting piece;

[0019] S2: When the second connecting piece rotates towards the (k + 1)-th first connection point position and abuts, and the fourth connecting piece rotates towards the k-th second connection point position and abuts, parallel connection of adjacent battery cells is achieved; when the second connecting piece rotates towards the (k + 1)-th second connection point position, and the fourth connecting piece rotates towards the k-th first connection point position, series connection of adjacent battery cells is achieved; when the second connecting piece and the fourth connecting piece are in the initial position, the conversion circuit is in an open circuit state;

[0020] S3: The BMS obtains the real-time voltage of each single battery cell from the first connection point position corresponding to each battery cell and a plurality of second connection point positions respectively, and then connects the battery cells in series through the conversion circuit;

[0021] S4: If the BMS detects that at least one battery cell has an abnormal voltage, before charging, the abnormal battery cells are formed into independent circuits one by one, and the normal battery cells are skipped: if the abnormal battery cell is the n-th battery cell, n ∈ N + 1, then the second connecting pieces of each first switching unit before the n-th battery cell are placed in the initial position, the second connecting pieces of each first switching unit after the n-th battery cell are electrically connected to the adjacent first connection point positions behind, the fourth connecting pieces of each second switching unit before the n-th battery cell are electrically connected to the adjacent second connection point positions in front, the fourth connecting pieces of each second switching unit after the n-th battery cell are placed in the initial position, and the abnormal battery cells forming independent circuits are charged with the rated current until each abnormal battery cell reaches the set charging time;

[0022] S5: The BMS drives the conversion circuit to connect N + 1 battery cells in parallel. At this time, the second connecting piece of the first first switching unit is electrically connected to the second first connection point, the second connecting piece of the second first switching unit is electrically connected to the third first connection point, and so on. The second connecting piece of the Nth first switching unit is electrically connected to the (N + 1)th first connection point; meanwhile, the fourth connecting piece of the first second switching unit is electrically connected to the first second connection point, the fourth connecting piece of the second second switching unit is electrically connected to the first second connection point, and so on. The fourth connecting piece of the Nth second switching unit is electrically connected to the Nth second connection point. At this time, N + 1 battery cells are connected in parallel between the positive bus bar and the negative bus bar; maintain the current state for a period of time until the battery cells reach a static state;

[0023] S6: The BMS detects whether the static pressure difference between battery cells exceeds the static pressure difference threshold. If it exceeds the static pressure difference threshold, return to step S5; if it does not exceed the static pressure difference threshold, the BMS drives the conversion circuit to connect the battery cells in series and perform series charging;

[0024] S7: After the series charging reaches the set time, the BMS respectively detects the dynamic voltages of each battery cell. If the dynamic pressure difference between the battery cells exceeds the dynamic pressure difference threshold, return to execute step S5; if the dynamic pressure difference between the battery cells does not exceed the dynamic pressure difference threshold, it means that the charging balance is completed.

[0025] Preferably, in step S4, the BMS stores the battery cells with abnormal voltages. If any of the following situations of the battery cells with abnormal voltages reaches a specific number of times, it prompts to replace the corresponding battery cell:

[0026] 1) Each time the same battery cell needs to be balanced during charging and the balanced charge is greater than 0.3% of the rated capacity;

[0027] 2) Each time the same battery cell needs to be balanced during charging, and the balancing actions are all discharges;

[0028] 3) Each time the same battery cell needs to be balanced during charging, and the charging or discharging capacity deviates from that of normal battery cells by more than 3%.

[0029] Preferably, the charging time set in step S4 is The overvoltage capacity of the lithium battery is xC, where C is the charging current multiple.

[0030] Preferably, the static pressure difference threshold described in step S6 is 10 mV.

[0031] Preferably, the dynamic pressure difference threshold described in step S7 is 100 mV.

[0032] An active adjustable equalization battery and equalization method provided by the present invention have the following beneficial effects compared with the prior art:

[0033] (1) The BMS system monitors the voltage of each battery cell and automatically adjusts the series and parallel connection modes of the battery pack according to voltage abnormalities, realizing dynamic adjustment of the charging state of the battery pack. This active adjustment not only improves the utilization efficiency of the battery but also extends the service life of the battery; accurately controls the switching states of the first switching unit and the second switching unit, and flexibly realizes the series and parallel charging and discharging of the battery cells. Especially when detecting voltage abnormalities in the battery, the BMS can independently handle the problematic battery cells. The independent charging and dynamic balancing technology of the abnormal battery cells ensures that the battery pack can specifically correct the power differences of the battery cells during the charging process, improving the reliability of the battery;

[0034] (2) The BMS detects the voltage state of the battery cells during each charging. Through the set charging time threshold and dynamic / static voltage difference threshold, the solution can accurately determine whether the battery has reached the ideal charging state, and decide whether to continue charging or adjust the battery configuration according to the voltage difference situation, and automatically trigger the adjustment or alarm mechanism when detecting voltage abnormalities. This helps to timely detect the battery cells with degraded performance or faults, and avoid battery damage or safety accidents caused by overcharging or over-discharging. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a block diagram of the battery structure of an active adjustable balanced battery and a balancing method according to the present invention;

[0037] Figure 2 It is a schematic diagram of the conversion circuit of an active adjustable balanced battery and a balancing method according to the present invention in the initial state;

[0038] Figure 3 It is a schematic diagram of the conversion circuit of an active adjustable balanced battery and a balancing method according to the present invention connecting each battery cell in series;

[0039] Figure 4 It is a schematic diagram of the conversion circuit of an active adjustable balanced battery and a balancing method according to the present invention connecting each battery cell in parallel;

[0040] Figure 5 It is a wiring schematic diagram of the conversion circuit of an active adjustable balanced battery and a balancing method according to the present invention forming an independent circuit for the abnormal battery cells;

[0041] Figure 6 This is the flowchart of the steps of an active adjustable equalization battery and an equalization method according to the present invention. Specific embodiments

[0042] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] As Figure 1 shown, the present invention provides an active adjustable equalization battery, including:

[0044] A number of battery cells are stacked in sequence, and both ends of each of the number of battery cells include a positive electrode and a negative electrode arranged at intervals;

[0045] A conversion circuit is provided with a number of first connection points and a number of second connection points arranged in pairs. The number of first connection points are electrically connected to the positive electrodes of the number of battery cells in one-to-one correspondence, and the number of second connection points are electrically connected to the negative electrodes of the number of battery cells in one-to-one correspondence; the conversion circuit is also electrically connected to the positive bus bar and the negative bus bar;

[0046] A BMS is electrically connected to the number of battery cells and the conversion circuit respectively to obtain the individual voltages of the number of battery cells;

[0047] Among them, the BMS also changes the connection state of the first connection point and the second connection point of the conversion circuit to switch adjacent battery cells, so as to achieve series charge and discharge of the number of battery cells, parallel charge and discharge of the number of battery cells, or charge and discharge of a single battery cell.

[0048] The conversion circuit can sequentially connect the first connection points at the same end of each battery cell to the positive electrode of the vector battery cell, and sequentially connect the second connection points at the other end of each battery cell to the negative electrode of the vector battery cell to achieve parallel connection of each battery cell; the conversion circuit can also electrically connect the first connection point of each battery cell to the second connection point of the adjacent battery cell, so as to achieve series connection of each battery cell.

[0049] From Figure 1 this, it can be seen that the conversion circuit can be integrated on a circuit board and arranged on one side of the battery cell provided with positive and negative terminals, and various components of the conversion circuit can be integrated in the form of a circuit board. Figure 1The shown 1+, 1-, 2+, 2-, ……, (N+1)+, (N+1)- are respectively the first connection points and the second connection points corresponding to the positive and negative electrodes of N+1 battery cells. The conversion circuit further includes a plurality of first switching units 100 and a plurality of second switching units 200. The first switching units 100 are arranged between adjacent first connection points, and the second switching units 200 are arranged between adjacent second connection points; one end of the first switching unit 100 is electrically connected to the first connection point corresponding to the current battery cell, one end of the second switching unit 200 is electrically connected to the second connection point corresponding to the battery cell adjacent to the current battery cell, the other end of the first switching unit 100 is rotatable relative to the first connection point, and the other end of the second switching unit 200 is rotatable relative to the second connection point. The first switching units 100 and the second switching units 200 are arranged between adjacent battery cells, so the number of both the first switching units 100 and the second switching units 200 is N.

[0050] As Figure 2 , Figure 3 and Figure 4 shown, the number of both the first switching units 100 and the second switching units 200 is N; the first switching unit 100 includes a first connecting piece 101 and a second connecting piece 102; for the k-th first switching unit 100, k = 1, 2, …, N, one end of the first connecting piece 101 is fixedly connected to the k-th first connection point, and the other end of the first connecting piece 101 is hinged to one end of the second connecting piece 102;

[0051] The second switching unit 200 includes a third connecting piece 201 and a fourth connecting piece 202; for the k-th second switching unit 200, one end of the third connecting piece 201 is fixedly connected to the (k+1)-th second connection point, and the other end of the third connecting piece 201 is hinged to one end of the fourth connecting piece 202;

[0052] The second connecting piece 102 rotates towards the (k+1)-th first connection point and abuts, and the fourth connecting piece 202 rotates towards the k-th second connection point and abuts, to realize the parallel connection of adjacent battery cells; the second connecting piece 102 rotates towards the direction of the (k+1)-th second connection point, and the fourth connecting piece 202 rotates towards the k-th first connection point, to realize the series connection of adjacent battery cells.

[0053] A current-limiting resistor is further arranged on the second connecting piece 102. Specifically, the setting position of the current-limiting resistor is between the overlapping position of the second connecting piece 102 and the fourth connecting piece 202 and the end of the second connecting piece 102 far from the first connecting piece 101. When adjacent battery cells are connected in parallel, the current-limiting resistor is connected into the circuit to play a role in current limiting to prevent the phenomenon of explosion and fire; when adjacent battery cells are connected in parallel, the overlapping position bypasses the current-limiting resistor, and at this time the current-limiting resistor will not be connected into the circuit, preventing the current-limiting resistor from being connected into the series circuit and affecting the performance of the battery.

[0054] As shown in Figure 2 , Figure 3 , Figure 4 Figure, the first switching unit 100 and the second switching unit 200 are microswitches or toggle switches. By an external electric push rod or a displacement mechanism, the second connecting piece 102 and the fourth connecting piece 202 are pushed to rotate clockwise or counterclockwise relative to the initial position, so as to achieve the formation of a series connection or a parallel connection of multiple battery cells.

[0055] As another embodiment, referring to the attached Figure 6 , the present invention also provides a balancing method for an active adjustable balanced battery, including the following steps:

[0056] S1: Configure an active adjustable balanced battery as described above; where the number of battery cells is N + 1, and the battery cells are stacked in sequence in the width direction; the conversion circuit has N first connection points and several second connection points arranged in pairs. The first connection points are electrically connected to the positive electrodes of the respective battery cells one by one, the second connection points are electrically connected to the negative electrodes of the respective battery cells one by one, the (N + 1)th first connection point is electrically connected to the positive busbar, and the first second connection point is electrically connected to the negative busbar; in order to distinguish different battery cells and the corresponding connection points, they are respectively marked, such as the battery cells are marked as 1, 2,..., N + 1; different first connection points and second connection points are marked as 1+, 1-, 2+, 2-,..., (N + 1)+, (N + 1)-.

[0057] The conversion circuit further includes several first switching units 100 and several second switching units 200; the first switching unit 100 includes a first connecting piece 101 and a second connecting piece 102; for the kth first switching unit 100, k = 1, 2,..., N, one end of the first connecting piece 101 is fixedly connected to the kth first connection point, and the other end of the first connecting piece 101 is hinged to one end of the second connecting piece 102; the second switching unit 200 includes a third connecting piece 201 and a fourth connecting piece 202; for the kth second switching unit 200, one end of the third connecting piece 201 is fixedly connected to the (k + 1)th second connection point, and the other end of the third connecting piece 201 is hinged to one end of the fourth connecting piece 202;

[0058] S2: When the second connecting piece 102 rotates towards the (k + 1)th first connection point and abuts, and the fourth connecting piece 202 rotates towards the kth second connection point and abuts, the parallel connection of adjacent battery cells is achieved; when the second connecting piece 102 rotates towards the direction of the (k + 1)th second connection point, and the fourth connecting piece 202 rotates towards the kth first connection point, the series connection of adjacent battery cells is achieved; when the second connecting piece 102 and the fourth connecting piece 202 are in the initial position, the conversion circuit is in an open state; as shown in Figure 2 ,Figure 3 and Figure 4 as shown Figure 2 winning the open - circuit state of the conversion circuit Figure 3 corresponds to the series state of the conversion circuit Figure 4 corresponds to the parallel state of the conversion circuit

[0059] S3: The BMS obtains the real - time voltage of each single cell from the first connection point corresponding to each cell and several second connection points respectively, and then connects the cells in series through the conversion circuit;

[0060] S4: If the BMS detects that at least one cell has an abnormal voltage, before charging, the abnormal cells are formed into independent circuits one by one, and the normal cells are skipped. If the abnormal cell is the nth cell, n ∈ N + 1, then the second connecting pieces 102 of each first switching unit 100 before the nth cell are placed in the initial position, the second connecting pieces 102 of each first switching unit 100 after the nth cell are electrically connected to the adjacent first connection point behind, the fourth connecting pieces 202 of each second switching unit 200 before the nth cell are electrically connected to the adjacent second connection point in front, the fourth connecting pieces 202 of each second switching unit 200 after the nth cell are placed in the initial position, and the abnormal cells forming independent circuits are charged with the rated current until each abnormal cell reaches the set charging time;

[0061] such as Figure 5 as shown, the figure shows the state of the conversion circuit when the voltage of a single cell is abnormal. Assuming that the voltage of the third cell is abnormal, each first switching unit 100 after the third cell electrically connects the adjacent first connection points respectively, and each first switching unit 100 before the third cell electrically connects the adjacent second connection points, and the remaining first connection points and second connection points are open - circuit. That is, between the positive bus bar and the negative bus bar, currently only the abnormal third cell forms a loop, and the third cell is charged and balanced alone. For example, charging is carried out with the rated charging voltage and current of the single cell. The set charging time mentioned here is The over - voltage capacity of the lithium - ion battery is xC, where C is the charging current multiple. That is, when charging the battery at the charging current multiple C, it can be fully charged in 1 hour.

[0062] During the execution of step S4, the BMS stores the cells with abnormal voltage. If any of the following situations of the cells with abnormal voltage reaches a specific number of times, it prompts to replace the corresponding cell:

[0063] 1) Each time the same cell needs to be balanced during charging and the balanced charge is greater than 0.3% of the rated capacity;

[0064] 2) Each charge of the same battery cell requires balancing, and the balancing actions are all manifested as discharging;

[0065] 3) Each charge of the same battery cell requires balancing, and it is manifested as the charging power or the discharged power deviating from that of a normal battery cell by more than 3%.

[0066] Here, reaching a specific number of times can be continuous abnormal reaching times, is the ceiling symbol.

[0067] S5: The BMS drives the conversion circuit to connect N + 1 battery cells in parallel. At this time, the second connecting piece 102 of the first first switching unit 100 is electrically connected to the second first connection point, the second connecting piece 102 of the second first switching unit 100 is electrically connected to the third first connection point, and so on. The second connecting piece 102 of the Nth first switching unit 100 is electrically connected to the (N + 1)th first connection point; at the same time, the fourth connecting piece 202 of the first second switching unit 200 is electrically connected to the first second connection point, the fourth connecting piece 202 of the second second switching unit 200 is electrically connected to the first second connection point, and so on. The fourth connecting piece 202 of the Nth second switching unit 200 is electrically connected to the Nth second connection point. At this time, N + 1 battery cells are connected in parallel between the positive bus bar and the negative bus bar; maintain the current state for a period of time until the battery cells reach a static state; when the battery cells reach a static state, usually N + 1 battery cells need to be connected in parallel and maintained for at least 10 minutes.

[0068] S6: The BMS detects whether the static pressure difference between each battery cell exceeds the static pressure difference threshold. If it exceeds the static pressure difference threshold, return to step S5; if it does not exceed the static pressure difference threshold, the BMS drives the conversion circuit to connect each battery cell in series and perform series charging;

[0069] In one embodiment, the static pressure difference threshold is 10 mV.

[0070] S7: After the series charging reaches the set time, the BMS respectively detects the dynamic voltages of each battery cell. If the dynamic pressure difference between each battery cell exceeds the dynamic pressure difference threshold, return to execute step S5; if the dynamic pressure difference between each battery cell does not exceed the dynamic pressure difference threshold, it means that the charging balance is completed.

[0071] In one embodiment, the dynamic pressure difference threshold is 100 mV.

[0072] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An active adjustable balancing battery, characterized in that: include: A plurality of battery cells are stacked in sequence, and each of the end faces of the battery cells includes a positive electrode and a negative electrode spaced apart; The conversion circuit is provided with a plurality of first connection points and a plurality of second connection points arranged in pairs, wherein the plurality of first connection points are electrically connected to the positive electrodes of the plurality of battery cells in a one-to-one correspondence, and the plurality of second connection points are electrically connected to the negative electrodes of the plurality of battery cells in a one-to-one correspondence; the conversion circuit is also electrically connected to the positive busbar and the negative busbar; The BMS is electrically connected to the battery cells and the conversion circuit to obtain the single cell voltages of the battery cells; Among them, the BMS also changes the connection status of the first connection point and the second connection point of the conversion circuit to switch the adjacent battery cells, so as to realize the series charging and discharging of several battery cells, the parallel charging and discharging of several battery cells, or the charging and discharging of a single battery cell.

2. The active adjustable balancing battery according to claim 1, characterized in that: The conversion circuit also includes a plurality of first switching units and a plurality of second switching units, the first switching units are arranged between adjacent first connection points, and the second switching units are arranged between adjacent second connection points; one end of the first switching unit is electrically connected to the first connection point corresponding to the current battery cell, and one end of the second switching unit is electrically connected to the second connection point corresponding to the battery cell adjacent to the current battery cell, the other end of the first switching unit is rotatable relative to the first connection point, and the other end of the second switching unit is rotatable relative to the second connection point.

3. The active adjustable balancing battery according to claim 2, characterized in that: The number of the first switching unit and the second switching unit is N; the first switching unit includes a first connecting piece and a second connecting piece; for the kth first switching unit, k=1, 2, ..., N, one end of the first connecting piece is fixedly connected to the kth first connection point, and the other end of the first connecting piece is hinged to one end of the second connecting piece; The second switching unit includes a third connecting piece and a fourth connecting piece; for the kth second switching unit, one end of the third connecting piece is fixedly connected to the k+1th second connection point, and the other end of the third connecting piece is hinged to one end of the fourth connecting piece; The second connecting piece rotates and abuts toward the k+1th first connecting point, and the fourth connecting piece rotates and abuts toward the kth second connecting point, to achieve parallel connection of adjacent battery cells; the second connecting piece rotates toward the k+1th second connecting point, and the fourth connecting piece rotates toward the kth first connecting point, to achieve series connection of adjacent battery cells.

4. The active adjustable balancing battery according to claim 3, characterized in that: A current limiting resistor is also provided on the second connecting piece.

5. The active adjustable balancing battery according to claim 3, characterized in that: The first switching unit and the second switching unit are micro switches or toggle switches.

6. A method for balancing an active adjustable balancing battery, characterized in that: The steps include: S1: An active adjustable balancing battery according to any one of claims 1 to 5 is configured; wherein the number of battery cells is N+1, and the battery cells are stacked sequentially in the width direction; the conversion circuit has N first connection points and a plurality of second connection points arranged in pairs, wherein the first connection points are electrically connected to the positive electrodes of the battery cells in a one-to-one correspondence, the second connection points are electrically connected to the negative electrodes of the battery cells in a one-to-one correspondence, the N+1th first connection point is electrically connected to the positive busbar, and the first second connection point is electrically connected to the negative busbar; The conversion circuit further includes a plurality of first switching units and a plurality of second switching units; the first switching unit includes a first connecting piece and a second connecting piece; for the kth first switching unit, k=1, 2, ..., N, one end of the first connecting piece is fixedly connected to the kth first connection point, and the other end of the first connecting piece is hingedly connected to one end of the second connecting piece; the second switching unit includes a third connecting piece and a fourth connecting piece; for the kth second switching unit, one end of the third connecting piece is fixedly connected to the k+1th second connection point, and the other end of the third connecting piece is hingedly connected to one end of the fourth connecting piece; S2: When the second connecting piece rotates toward and abuts the k+1th first connection point, and the fourth connecting piece rotates toward and abuts the kth second connection point, adjacent battery cells are connected in parallel; when the second connecting piece rotates toward the k+1th second connection point, and the fourth connecting piece rotates toward the kth first connection point, adjacent battery cells are connected in series; when the second connecting piece and the fourth connecting piece are in the initial position, the conversion circuit is in an open circuit state; S3: The BMS obtains the real-time voltage of each battery cell from the first connection point and several second connection points corresponding to each battery cell, and then connects the battery cells in series through the conversion circuit; S4: If the BMS detects that at least one battery cell has a voltage abnormality, before charging, the abnormal battery cells are formed into independent circuits one by one, and the normal battery cells are skipped: if the abnormal battery cell is the nth battery cell, n∈N+1, the second connecting piece of each first switching unit before the nth battery cell is placed in the initial position, the second connecting piece of each first switching unit after the nth battery cell is electrically connected to the first connecting point adjacent to the rear, the fourth connecting piece of each second switching unit before the nth battery cell is electrically connected to the second connecting point adjacent to the front, and the fourth connecting piece of each second switching unit after the nth battery cell is placed in the initial position, and the abnormal battery cells that form the independent circuit are charged with the rated current until each abnormal battery cell reaches the set charging time; S5: The BMS drives the conversion circuit to connect N+1 cells in parallel. At this time, the second connecting piece of the first first switching unit is electrically connected to the second first connection point, the second connecting piece of the second first switching unit is electrically connected to the third first connection point, and so on. The second connecting piece of the Nth first switching unit is electrically connected to the N+1th first connection point; at the same time, the fourth connecting piece of the first second switching unit is electrically connected to the first second connection point, the fourth connecting piece of the second second switching unit is electrically connected to the first second connection point, and so on. The fourth connecting piece of the Nth second switching unit is electrically connected to the Nth second connection point. At this time, N+1 cells are arranged in parallel between the positive bus and the negative bus; maintain the current state for a period of time until the cell reaches a static state; S6: The BMS detects whether the static pressure difference of each battery cell exceeds the static pressure difference threshold. If so, the process returns to step S5. If not, the BMS drives the conversion circuit to connect the battery cells in series and charge them in series. S7: After the series charging reaches the set time, the BMS detects the dynamic voltage of each battery cell respectively. If the dynamic voltage difference of each battery cell exceeds the dynamic voltage difference threshold, it returns to step S5; if the dynamic voltage difference of each battery cell does not exceed the dynamic voltage difference threshold, it means that charging balancing is completed.

7. The method for balancing an active adjustable balancing battery according to claim 6, characterized in that: In step S4, the BMS stores the cells with abnormal voltages. If the cells with abnormal voltages have any of the following conditions for a certain number of times, it will prompt you to replace the corresponding cells: 1) Each charge of the same battery cell needs to be balanced and the balanced charge must be greater than 0.3% of the rated capacity; 2) Each charge of the same battery cell requires balancing, and the balancing action is always manifested as discharge; 3) Each charge of the same battery cell needs to be balanced, and the performance is that the charging capacity or discharged capacity deviates from the normal battery cell by more than 3%.

8. The active adjustable balancing battery balancing method according to claim 6, characterized in that: The charging time set in step S4 is The overvoltage capability of a lithium battery is xC, where C is the charge current rate.

9. The active adjustable balancing battery balancing method according to claim 6, characterized in that: The static voltage difference threshold in step S6 is 10 mV.

10. The active adjustable balancing battery balancing method according to claim 6, characterized in that: The dynamic voltage difference threshold in step S7 is 100 mV.

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