Charge and discharge balancing method and apparatus for battery pack

Abstract

A charge and discharge balancing method and apparatus for a battery pack. The charge and discharge balancing method for a battery pack comprises: acquiring a charging / discharging state of a battery pack and a charging / discharging state of a balancing energy storage module (S110); if the balancing energy storage module is in the charging state, balancing a cell having the maximum state of charge in the battery pack on the basis of the charging / discharging state of the battery pack, so as to balance the states of charge of a plurality of cells in the battery pack (S130); and if the balancing energy storage module is in the discharging state, balancing the states of charge of the plurality of cells in the battery pack on the basis of the charging / discharging state of the battery pack (S140).

Description

Battery Pack Charge / Discharge Equalization Method and Apparatus

[0001] This application claims priority to Chinese Patent Application No. 202411937708.X, filed with the Chinese Patent Office on December 26, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery pack technology, for example to a battery pack charge-discharge equalization method and apparatus. Background Technology

[0003] Active balancing technology addresses the "weakest link" effect in a battery pack by redistributing energy among multiple cells. This technology transfers energy from cells with high State of Charge (SOC) to cells with low SOC, avoiding energy loss due to heat and increasing the total usable energy of the battery pack.

[0004] However, cells with lower State of Health (SOH) in the battery pack undergo more charge-discharge cycles during balancing. This leads to faster aging of these low SOH cells and a shorter battery pack lifespan. Summary of the Invention

[0005] This application provides a battery pack charge-discharge balancing method and apparatus to delay the decline in the health of the battery cells and improve the service life of the battery pack.

[0006] According to one aspect of this application, a battery pack charge-discharge balancing method is provided, applied to a battery pack charge-discharge balancing device, the battery pack charge-discharge balancing device comprising: an energy storage balancing module; the battery pack charge-discharge balancing method comprising:

[0007] Obtain the charging and discharging status of the battery pack and the charging and discharging status of the equalization energy storage module;

[0008] If the equalization energy storage module is in a charging state, the cells with the largest state of charge in the battery pack are equalized according to the charging and discharging state of the battery pack, so as to equalize the state of charge of multiple cells in the battery pack.

[0009] If the equalization energy storage module is in a discharging state, the state of charge of multiple cells in the battery pack is equalized according to the charging and discharging state of the battery pack.

[0010] Optionally, the battery pack charge / discharge balancing device further includes: a balancing charging module; the step of balancing the cells with the highest state of charge in the battery pack according to the charge / discharge state of the battery pack, so as to balance the state of charge of multiple cells in the battery pack, includes:

[0011] If the battery pack is in a charging state, the cell with the largest state of charge in the battery pack is connected to the equalization energy storage module through the equalization charging module, and the cell with the largest state of charge in the battery pack is equalized according to the charging current of the battery pack.

[0012] If the battery pack is in a discharging state, the cell with the highest state of charge in the battery pack is connected to the equalization energy storage module through the equalization charging module to equalize the state of charge of multiple cells in the battery pack.

[0013] Optionally, the battery pack charge / discharge balancing device further includes: a balancing switch module; the step of connecting the cell with the highest state of charge in the battery pack to the balancing energy storage module through the balancing charging module, and balancing the cell with the highest state of charge in the battery pack according to the charging current of the battery pack, includes:

[0014] The cell with the largest state of charge in the battery pack is determined based on the state of charge of multiple cells in the battery pack.

[0015] The equalization switch module controls the connection between the battery cell with the highest state of charge in the battery pack and the equalization charging module.

[0016] The output of the equalization charging module is controlled according to the charging current to balance the state of charge of multiple cells in the battery pack.

[0017] Optionally, the battery pack charge / discharge balancing device further includes: a balancing charging module and a balancing discharging module; the step of balancing the state of charge of multiple cells in the battery pack according to the charge / discharge state of the battery pack includes:

[0018] If the battery pack is in a charging state, then determine whether the battery pack is in a constant current charging mode;

[0019] If the battery pack is in constant current charging mode, the equalization energy storage module is connected to the cell with the lowest state of charge in the battery pack through the equalization discharge module, so as to equalize the state of charge of multiple cells in the battery pack.

[0020] If the battery pack is not in constant current charging mode, the cell with the largest state of charge in the battery pack is connected to the cell with the smallest state of charge in the battery pack through the equalization charging module, the equalization energy storage module and the equalization discharging module, so as to equalize the state of charge of multiple cells in the battery pack.

[0021] If the battery pack is in a discharging state, the equalization energy storage module is connected to the cell with the lowest state of charge in the battery pack through the equalization discharge module, and the cell with the lowest state of charge in the battery pack is equalized according to the discharge current of the battery pack.

[0022] Optionally, the battery pack charge / discharge balancing device further includes: a balancing switch module; connecting the balancing energy storage module to the cell with the lowest state of charge in the battery pack through the balancing discharge module, and balancing the cell with the lowest state of charge in the battery pack according to the discharge current of the battery pack, including:

[0023] The cell with the lowest state of charge in the battery pack is determined based on the state of charge of multiple cells in the battery pack.

[0024] The equalization switch module controls the connection between the cell with the lowest state of charge in the battery pack and the equalization discharge module.

[0025] The output of the equalization discharge module is controlled according to the discharge current to equalize the state of charge of multiple cells in the battery pack.

[0026] According to another aspect of this application, a battery pack charge-discharge balancing device is also provided, wherein the battery pack includes a plurality of cells connected in series; the battery pack charge-discharge balancing device includes: a balancing switch module, a balancing charging module, a balancing discharging module, a balancing energy storage module, and a control module;

[0027] Multiple battery cells are connected to the equalization charging module and the equalization discharging module via an equalization switch module. The multiple battery cells are also connected to the control module. The equalization charging module and the equalization discharging module are both connected to the equalization energy storage module. The equalization switch module, the equalization charging module, the equalization discharging module, and the equalization energy storage module are also connected to the control module.

[0028] The equalization switch module is configured to control the connection between the multiple battery cells and the equalization charging module or the equalization discharging module; the equalization charging module is configured to charge the equalization energy storage module; the equalization discharging module is configured to discharge the equalization energy storage module; the equalization energy storage module is configured to equalize the multiple battery cells through charging and discharging; the control module is configured to execute the battery pack charge-discharge equalization method.

[0029] Optionally, the equalization switch module includes: an equalization switch unit, a charging switch unit, and a discharging switch unit;

[0030] The plurality of battery cells are all connected to the equalization switch unit. The first and second ends of the charging switch unit are both connected to the equalization switch unit. The first end of the discharging switch unit is connected to the first end of the charging switch unit. The second end of the discharging switch unit is connected to the second end of the charging switch unit. The third and fourth ends of the charging switch unit are both connected to the equalization charging module. The third and fourth ends of the discharging switch unit are both connected to the equalization discharging module.

[0031] The equalization switch unit is configured to control the connection between the plurality of battery cells and the charging switch unit or the discharging switch unit; the charging switch unit is configured to change the polarity of the battery cells and control the connection between the equalization switch unit and the equalization charging module; the discharging switch unit is configured to change the polarity of the battery cells and control the connection between the equalization switch unit and the equalization discharging module.

[0032] Optionally, the equalization switching unit includes: a plurality of first switches and a plurality of second switches;

[0033] The first ends of the plurality of first switches are connected to the first end of the charging switch unit, the first ends of the plurality of second switches are connected to the second end of the charging switch unit, the second ends of the plurality of first switches and the second ends of the plurality of second switches are connected to the plurality of battery cells in an alternating manner, and the two ends of each battery cell are respectively connected to the first switch and the second switch.

[0034] Optionally, the charging switch unit includes: a first charging switch, a second charging switch, a first charging reversing switch, and a second charging reversing switch;

[0035] The first end of the first charging switch serves as the first end of the charging switch unit, the second end of the first charging switch serves as the third end of the charging switch unit, the first end of the second charging switch serves as the second end of the charging switch unit, the second end of the second charging switch serves as the fourth end of the charging switch unit, the first end of the first charging reversing switch is connected to the first end of the first charging switch, the second end of the first charging reversing switch is connected to the second end of the second charging switch, the first end of the second charging reversing switch is connected to the first end of the second charging switch, and the second end of the second charging reversing switch is connected to the second end of the first charging switch.

[0036] Optionally, the discharge switch unit includes: a first discharge switch, a second discharge switch, a first discharge reversing switch, and a second discharge reversing switch;

[0037] The first end of the first discharge switch serves as the first end of the discharge switch unit, the second end of the first discharge switch serves as the third end of the discharge switch unit, the first end of the second discharge switch serves as the second end of the discharge switch unit, the second end of the second discharge switch serves as the fourth end of the discharge switch unit, the first end of the first discharge reversing switch is connected to the first end of the first discharge switch, the second end of the first discharge reversing switch is connected to the second end of the second discharge switch, the first end of the second discharge reversing switch is connected to the first end of the second discharge switch, and the second end of the second discharge reversing switch is connected to the second end of the first discharge switch. Attached Figure Description

[0038] Figure 1 is a schematic diagram of a battery pack charge-discharge equalization device provided in an embodiment of this application;

[0039] Figure 2 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application;

[0040] Figure 3 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application;

[0041] Figure 4 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application;

[0042] Figure 5 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application;

[0043] Figure 6 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application;

[0044] Figure 7 is a flowchart of a battery pack charge-discharge equalization method provided in an embodiment of this application;

[0045] Figure 8 is a flowchart of another battery pack charge-discharge equalization method provided in an embodiment of this application;

[0046] Figure 9 is a flowchart of another battery pack charge-discharge equalization method provided in an embodiment of this application. Detailed Implementation

[0047] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. The described embodiments are only some of the embodiments of this application, and not all of them.

[0048] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Such data may be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0049] This application provides a battery pack charge-discharge equalization device. The device includes an equalization switch module, an equalization charging module, an equalization discharging module, an equalization energy storage module, and a control module. The control module can be used to execute the battery pack charge-discharge equalization method provided in any embodiment of this application. To facilitate understanding of the battery pack charge-discharge equalization method provided in this application, the electrical structure of the battery pack charge-discharge equalization device using this method is described.

[0050] Figure 1 is a schematic diagram of a battery pack charge-discharge balancing device provided in an embodiment of this application. Referring to Figure 1, the battery pack includes multiple cells 10 connected in series, and the battery pack charge-discharge balancing device includes: a balancing switch module 110, a balancing charging module 120, a balancing discharging module 130, a balancing energy storage module 140, and a control module 150.

[0051] Multiple battery cells 10 are connected to an equalization charging module 120 and an equalization discharging module 130 via an equalization switch module 110. The multiple battery cells 10 are also connected to the control module 150. Both the equalization charging module 120 and the equalization discharging module 130 are connected to an equalization energy storage module 140. The equalization switch module 110, equalization charging module 120, equalization discharging module 130, and equalization energy storage module 140 are also connected to the control module 150. The equalization switch module 110 is configured to control the connection between the multiple battery cells 10 and the equalization charging module 120 or the equalization discharging module 130. The equalization charging module 120 is configured to charge the equalization energy storage module 140. The equalization discharging module 130 is configured to discharge the equalization energy storage module 140. The equalization energy storage module 140 is configured to discharge or charge the battery cells 10 to equalize the multiple battery cells 10. The control module 150 is configured to drive the equalization switch module 110, control the current of the equalization charging module 120 and the equalization discharging module 130, and control the charging and discharging state of the equalization energy storage module 140.

[0052] The control module 150 acquires the charging and discharging status of the battery pack and the charging and discharging status of the equalization energy storage module 140, and determines the equalization method of multiple cells 10 in the battery pack based on the charging and discharging status of the battery pack and the charging and discharging status of the equalization energy storage module 140.

[0053] When both the battery pack and the balancing energy storage module 140 are charging, the control module 150 determines the cell with the highest state of charge (SOC) within the battery pack based on a comparison of the SOCs of the multiple cells 10. The control module 150 then controls the balancing switch module 110 to connect the cell with the highest SOC to the balancing charging module 120, effectively opening a circuit between the cell with the highest SOC and the balancing charging module 120. At this time, the cell with the highest SOC is essentially connected in parallel with the balancing energy storage module 140, reducing its charging current and slowing down the change in its SOC, thus achieving balancing of the multiple cells 10 within the battery pack. The control module 150 also acquires the charging current of the battery pack and controls the current flowing through the balancing charging module 120 based on this current. The charging current of the cell with the highest SOC charges the balancing energy storage module 140 through the balancing charging module 120. The current output by the cell with the highest SOC is less than or equal to the charging current of the battery pack.

[0054] When the battery pack is charging and the equalization energy storage module 140 is discharging, the control module 150 determines the charging mode of the battery pack. When the battery pack is in constant current charging mode, the control module 150 determines the cell with the lowest state of charge in the battery pack based on a comparison of the states of charge of multiple cells 10. The control module 150 controls the equalization switch module 110 to connect the cell with the lowest state of charge to the equalization discharge module 130, that is, controls the equalization switch module 110 to open the circuit between the cell with the lowest state of charge and the equalization discharge module 130. At this time, the cell 10 with the lowest state of charge (SOC) is essentially connected in parallel with the balancing energy storage module 140. The discharge current of the balancing energy storage module 140 assists in charging the cell with the lowest SOC through the balancing discharge module 130. The cell 10 with the lowest SOC receives the additional discharge current from the balancing energy storage module 140 on top of the charging current of the battery pack. This increases the charging current of the cell 10 with the lowest SOC and accelerates the change in SOC of the cell 10, thereby achieving balancing of the multiple cells 10 within the battery pack. When the battery pack is in constant voltage charging mode, the control module 150 determines the cell 10 with the lowest SOC and the cell 10 with the highest SOC based on the comparison of the SOCs of the multiple cells 10. At this time, within the preset charging time, the control module 150 controls the balancing switch module 110 to connect the battery cell 10 with the highest state of charge (SOC) to the balancing energy storage module 140 through the balancing charging module 120, and controls the balancing energy storage module 140 to switch from a discharging state to a charging state to store the electrical energy output by the battery cell with the highest SOC. After the preset charging time ends, the control module 150 controls the connection between the battery cell 10 with the highest SOC and the balancing energy storage module 140 to disconnect, and controls the balancing energy storage module 140 to switch back to a discharging state. At this time, the control module 150 also controls the battery cell 10 with the lowest SOC to connect to the balancing energy storage module 140 through the balancing discharging module 130 to increase the charging current of the battery cell 10 with the lowest SOC, thereby accelerating the change in SOC of the battery cell 10 with the lowest SOC. The preset charging time is the pre-set charging time of the balancing energy storage module 140, which can be set according to actual needs in practical applications. This embodiment does not impose any restrictions on this.

[0055] When both the battery pack and the equalization energy storage module 140 are in a discharging state, the control module 150 determines the cell with the lowest state of charge (SOC) within the battery pack based on a comparison of the SOCs of the multiple cells 10. The control module 150 then controls the equalization switch module 110 to connect the cell with the lowest SOC to the equalization discharge module 130, effectively opening a circuit between the cell with the lowest SOC and the equalization discharge module 130. At this time, the cell with the lowest SOC is essentially connected in parallel with the equalization energy storage module 140. The equalization energy storage module 140 provides auxiliary discharge to the cell with the lowest SOC through the equalization discharge module 130. This provides a portion of the current for the discharge of the cell with the lowest SOC, reducing the discharge current and slowing down the change in SOC of the cell, thereby achieving equalization of the multiple cells 10 within the battery pack. The control module 150 also acquires the discharge current of the battery pack and controls the current flowing through the equalization discharge module 130 based on the discharge current of the battery pack. Specifically, the current output by the cell with the lowest state of charge is less than or equal to the discharge current of the battery pack.

[0056] When the battery pack is discharging and the balancing energy storage module 140 is charging, the control module 150 determines the cell with the highest state of charge (SOC) within the battery pack based on a comparison of the SOCs of the multiple cells 10. The control module 150 then controls the balancing switch module 110 to connect the cell with the highest SOC to the balancing charging module 120, effectively opening a circuit between the cell with the highest SOC and the balancing charging module 120. At this time, the cell with the highest SOC is essentially connected in parallel with the balancing energy storage module 140. The cell with the highest SOC, in addition to discharging externally, also charges the balancing energy storage module 140 through the balancing charging module 120, accelerating the change in SOC of the cell and thus achieving balancing of the multiple cells 10 within the battery pack. The control module 150 also acquires the charging current of the battery pack and controls the current flowing through the balancing charging module 120 based on this charging current.

[0057] This embodiment controls the connection between multiple battery cells 10 and the equalization charging module 120 or the equalization discharging module 130 through the equalization switch module 110, thereby controlling the connection between multiple battery cells 10 and the equalization energy storage module 140. The charging current of the battery cells 10 is shunted to the equalization energy storage module 140 through the equalization charging module 120 to charge the equalization energy storage module 140, or the equalization energy storage module 140 outputs to the battery cells 10 through the equalization discharging module 130 to assist in discharging the battery cells 10, so as to achieve equalization of multiple battery cells 10. This embodiment controls the connection between multiple battery cells 10 in the battery pack and the equalization charging module 120 or the equalization discharging module 130 through the equalization switch module 110, and realizes the charging and discharging of the equalization energy storage module 140 through the equalization charging module 120 and the equalization discharging module 130, respectively, so as to adjust the state of charge of the battery cells 10 in the battery pack, which helps to delay the decline of the health status of the battery cells 10 and improve the service life of the battery pack.

[0058] Figure 2 is a schematic diagram of another battery pack charge / discharge equalization device provided in an embodiment of this application. Optionally, based on the above embodiments and referring to Figure 2, the equalization switch module 110 includes: an equalization switch unit 111, a charging switch unit 112, and a discharging switch unit 113.

[0059] Multiple battery cells 10 are connected to an equalization switch unit 111. The first and second ends of a charging switch unit 112 are both connected to the equalization switch unit 111. The first end of a discharging switch unit 113 is connected to the first end of a charging switch unit 112, and the second end of a discharging switch unit 113 is connected to the second end of a charging switch unit 112. The third and fourth ends of a charging switch unit 112 are both connected to an equalization charging module 120, and the third and fourth ends of a discharging switch unit 113 are both connected to an equalization discharging module 130. The equalization switch unit 111 is configured to control the connection between the multiple battery cells 10 and the charging switch unit 112 or the discharging switch unit 113. The charging switch unit 112 is configured to change the polarity of the battery cells 10 and control the connection between the equalization switch unit 111 and the equalization charging module 120. The discharging switch unit 113 is configured to change the polarity of the battery cells 10 and control the connection between the equalization switch unit 111 and the equalization discharging module 130.

[0060] In some embodiments, the equalization charging module and the equalization discharging module can be integrated into one module, namely the equalization charging and discharging module. The equalization switch module is connected to the equalization energy storage module through the equalization charging and discharging module.

[0061] The equalization switch unit 111 is connected to multiple battery cells 10, and each battery cell 10 can be connected to the charging switch unit 112 and the discharging switch unit 113 through the equalization switch unit 111. The on / off state of the charging switch unit 112 and the discharging switch unit 113 is controlled by the control module 150. When the charging switch unit 112 is on, the charging current of the battery cell 10 is diverted to the equalization energy storage module 140 through the equalization charging module 120; when the discharging switch unit 113 is on, the equalization energy storage module 140 discharges through the equalization discharging module 130 to achieve auxiliary discharge of the battery cell 10. Optionally, referring to Figure 2, a battery pack current sensor 20 is also provided in the battery pack. The battery pack current sensor 20 is connected in series with the multiple battery cells 10 in the battery pack. The battery pack current sensor 20 is also connected to the control module 150. The battery pack current sensor 20 is configured to acquire the charging current and the discharging current of the battery pack.

[0062] Figure 3 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application. Optionally, based on the above embodiments and referring to Figure 3, the equalization switch unit 111 includes: a plurality of first switches K1 and a plurality of second switches K2.

[0063] The first ends of multiple first switches K1 are connected to the first end of charging switch unit 112, the first ends of multiple second switches K2 are connected to the second end of charging switch unit 112, and the second ends of multiple first switches K1 and multiple second switches K2 are connected to multiple battery cells 10 in an alternating manner. The two ends of each battery cell 10 are respectively connected to the first switch K1 and the second switch K2.

[0064] The first switch K1 and the second switch K2 are configured to control whether the battery cell 10 is connected to the charging switch unit 112 and the discharging switch unit 113. The first switch unit K1 and the second switch unit K2 are respectively connected to the two ends of the battery cell 10, namely the positive terminal and the negative terminal of the battery cell 10. When both the first switch K1 and the second switch K2 are closed, the battery cell 10 connected between the first end of the first switch K1 and the first end of the second switch K2 is connected to the charging switch unit 112 and the discharging switch unit 113.

[0065] Figure 4 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application. Optionally, based on the above embodiments, referring to Figure 4, the charging switch unit 112 includes: a first charging switch K3, a second charging switch K4, a first charging reversing switch K5, and a second charging reversing switch K6.

[0066] The first end of the first charging switch K3 serves as the first end of the charging switch unit 112, the second end of the first charging switch K3 serves as the third end of the charging switch unit 112, the first end of the second charging switch K4 serves as the second end of the charging switch unit 112, the second end of the second charging switch K4 serves as the fourth end of the charging switch unit 112, the first end of the first charging reversing switch K5 is connected to the first end of the first charging switch K3, the second end of the first charging reversing switch K5 is connected to the second end of the second charging switch K4, the first end of the second charging reversing switch K6 is connected to the first end of the second charging switch K4, and the second end of the second charging reversing switch K6 is connected to the second end of the first charging switch K3.

[0067] Based on the above embodiments, optionally, referring to FIG4, the discharge switch unit 113 includes: a first discharge switch K7, a second discharge switch K8, a first discharge reversing switch K9, and a second discharge reversing switch K10.

[0068] The first end of the first discharge switch K7 serves as the first end of the discharge switch unit 113, the second end of the first discharge switch K7 serves as the third end of the discharge switch unit 113, the first end of the second discharge switch K8 serves as the second end of the discharge switch unit 113, the second end of the second discharge switch K8 serves as the fourth end of the discharge switch unit 113, the first end of the first discharge reversing switch K9 is connected to the first end of the first discharge switch K7, the second end of the first discharge reversing switch K9 is connected to the second end of the second discharge switch K8, the first end of the second discharge reversing switch K10 is connected to the first end of the second discharge switch K8, and the second end of the second discharge reversing switch K10 is connected to the second end of the first discharge switch K7.

[0069] Referring to Figures 3 and 4, the polarity of the battery cell 10 varies depending on its position when connected to the charging switch unit 112 and the discharging switch unit 113. When the positive terminal of the battery cell 10 is connected to the first terminal of the charging switch unit 112 and the negative terminal is connected to the second terminal of the charging switch unit 112, the battery cell 10 is positively connected; when the negative terminal of the battery cell 10 is connected to the first terminal of the charging switch unit 112 and the positive terminal is connected to the second terminal of the charging switch unit 112, the battery cell 10 is reversed. When the battery cell 10 is reversed, its polarity needs to be reversed. For example, multiple battery cells 10 within the battery pack are connected in series. The positive or reverse connection of a battery cell 10 can be determined by its position. When a battery cell 10 is connected in series at an odd-numbered position within the battery pack, it is positively connected; when a battery cell 10 is connected in series at an even-numbered position within the battery pack, it is reversed.

[0070] When cell 10 is reverse-connected, the first charging reversing switch K5 and the second charging reversing switch K6 are closed to connect cell 10 to charging switch unit 112, or the first discharging reversing switch K9 and the second discharging reversing switch K10 are closed to connect cell 10 to discharging switch unit 113; when cell 10 is positive-connected, the first charging switch K3 and the second charging switch K4 are closed to connect cell 10 to charging switch unit 112, or the first discharging switch K7 and the second discharging switch K8 are closed to connect cell 10 to discharging switch unit 113.

[0071] Figure 5 is a schematic diagram of another battery pack charge-discharge equalization device provided in an embodiment of this application. Optionally, based on the above embodiments and referring to Figure 5, the equalization charging module 120 includes: a charging current sensor 121 and a charging DC transformer 122.

[0072] The input terminal of the charging current sensor 121 is connected to the equalization switch module 110, the output terminal of the charging current sensor 121 is connected to the positive input terminal of the charging DC transformer 122, the negative input terminal of the charging DC transformer 122 is connected to the equalization switch module 110, and both the positive and negative output terminals of the charging DC transformer 122 are connected to the equalization energy storage module 140.

[0073] Based on the above embodiments, optionally, referring to FIG5, the equalization discharge module 130 includes: a discharge current sensor 131 and a discharge DC transformer 132.

[0074] The positive and negative input terminals of the discharge DC transformer 132 are both connected to the equalization energy storage module 140. The positive output terminal of the discharge DC transformer 132 is connected to the input terminal of the discharge current sensor 131. The output terminal of the discharge current sensor 131 is connected to the equalization switch module 110. The negative output terminal of the discharge DC transformer 132 is connected to the equalization switch module 110.

[0075] The charging current sensor 121 is configured to detect the current when the battery cell 10 charges the equalization energy storage module 140. The control module 150 acquires the current detected by the charging current sensor 121 and controls the charging DC transformer 122 based on this current. When the current detected by the charging current sensor 121 is greater than the preset charging current, the control module 150 controls the charging DC transformer 122 to limit the current and reduce its magnitude.

[0076] The discharge current sensor 131 is configured to detect the current magnitude when the equalization energy storage module 140 charges the battery cell 10. The control module 150 acquires the current detected by the discharge current sensor 131 and controls the discharge DC transformer 132 based on this current. When the current detected by the discharge current sensor 131 is greater than the preset charging current, the control module 150 controls the discharge DC transformer 132 to limit the current, thereby reducing the current magnitude.

[0077] Figure 6 is a schematic diagram of another battery pack charge / discharge balancing device provided in an embodiment of this application. Optionally, based on the above embodiments, referring to Figure 6, the balancing energy storage module 140 includes: a plurality of balancing cells 141; the plurality of balancing cells 141 are connected in parallel. The positive and negative terminals of the plurality of balancing cells 141 are both connected to the balancing charging module 120 and the balancing discharging module 130.

[0078] This application provides a battery pack charge / discharge equalization method. This method is applied to a battery pack charge / discharge equalization device. It controls the connection between multiple cells within the battery pack and the equalization charging or discharging module by controlling an equalization switch module. The equalization charging and discharging modules respectively charge and discharge the equalization energy storage module, thereby adjusting the state of charge of the cells within the battery pack. This helps to slow down the decline in the health of the cells and improve the lifespan of the battery pack.

[0079] Figure 7 is a flowchart of a battery pack charge-discharge equalization method provided in an embodiment of this application. This battery pack charge-discharge equalization method is executed by the control module of the battery pack charge-discharge equalization device provided in any of the above embodiments. The battery pack charge-discharge equalization device includes: an equalization switch module, an equalization charging module, an equalization discharging module, an equalization energy storage module, and a control module. Referring to Figure 7, the battery pack charge-discharge equalization method includes:

[0080] S110: Obtain the charging and discharging status of the battery pack and the charging and discharging status of the equalization energy storage module.

[0081] For example, the state of charge / discharge of the battery pack can be obtained by monitoring the voltage of each cell and the entire battery pack. During charging, the voltage gradually increases as the charge increases; during discharging, the voltage gradually decreases. The state of charge / discharge of the equalization energy storage module can be obtained by detecting the voltage of the equalization energy storage module. During charging, the voltage of the equalization energy storage module rises; during discharging, the voltage of the equalization energy storage module falls.

[0082] S120. Determine the charging and discharging state of the equalization energy storage module; if the equalization module is in the charging state, execute S130; if the equalization module is in the discharging state, execute S140.

[0083] When the state of charge (SBC) of the balancing energy storage module is less than the charging threshold, it switches to charging mode, during which it only charges. When the SBC of the balancing energy storage module is greater than the discharging threshold, it switches to discharging mode, during which it only discharges. The charging threshold is the threshold value for charging the balancing energy storage module, and the discharging threshold is the threshold value for discharging the balancing energy storage module. In practical applications, the charging threshold and discharging threshold can be set according to actual needs; this embodiment does not impose any restrictions on this.

[0084] S130. The cells with the highest state of charge in the battery pack are balanced according to the charging and discharging state of the battery pack, so as to balance the state of charge of multiple cells in the battery pack.

[0085] The control module determines the cell with the highest state of charge (SOC) within the battery pack by comparing the SOC of multiple cells. The control module then controls the balancing switch module to connect this SOC to the balancing charging module, effectively establishing a circuit between the SOC and the balancing charging module. At this point, the SOC is essentially connected in parallel with the balancing energy storage module. When the battery pack is charging, the balancing energy storage module diverts a portion of the charging current, reducing the charging current of the SOC and slowing the increase in SOC, thus achieving balancing among the multiple cells in the battery pack. When the battery pack is discharging, the SOC, while discharging externally, also outputs additional current to charge the balancing energy storage module, increasing its discharge current and accelerating the decrease in SOC, further achieving balancing among the multiple cells in the battery pack.

[0086] S140. Balance the state of charge of multiple cells in the battery pack according to the charging and discharging state of the battery pack.

[0087] When the equalization energy storage module is in a discharging state, the equalization method of multiple cells in the battery pack needs to be determined according to the charging and discharging state of the battery pack.

[0088] When the battery pack is charging, the balancing method for the multiple cells within the pack is determined based on the charging mode. The charging modes are divided into constant current charging mode and constant voltage charging mode. In constant current charging mode, the charging current remains constant. In this mode, the balancing energy storage module can be connected in parallel to the cell with the lowest state of charge (SOC), providing additional charging current to accelerate the charging of this cell and thus balancing the SOC of the multiple cells. In constant voltage charging mode, the charging voltage remains constant. In this mode, the energy from the cell with the highest SOC can be transferred to the cell with the lowest SOC to balance the SOC of the multiple cells.

[0089] When the battery pack is in a discharging state, the equalization energy storage module can be connected in parallel to the cell with the lowest state of charge in the battery pack. This provides a portion of the discharge current to the cell with the lowest state of charge, reducing its own external discharge current and thus slowing down the rate of energy reduction of the cell with the lowest state of charge. This, in turn, balances the state of charge of multiple cells in the battery pack.

[0090] This application embodiment determines the cells within the battery pack that need to be balanced based on the charge / discharge state of the battery pack and the charge / discharge state of the balancing energy storage module. It also determines the balancing method for the cells within the battery pack based on the charge / discharge state of the battery pack and the charge / discharge state of the balancing energy storage module. By charging and discharging the cells within the battery pack that need to be balanced, the state of charge of the cells within the battery pack is adjusted, which helps to delay the decline in the health of the cells and improve the service life of the battery pack.

[0091] Figure 8 is a flowchart of another battery pack charge-discharge balancing method provided in an embodiment of this application. Optionally, based on the above embodiments and referring to Figure 8, the cells with the highest state of charge within the battery pack are balanced according to the charge-discharge state of the battery pack, in order to balance the state of charge of multiple cells within the battery pack, including:

[0092] S131. Determine the charging / discharging state of the battery pack; if the battery pack is charging, execute S132; if the battery pack is discharging, execute S133.

[0093] For example, the state of charge / discharge of the battery pack can be obtained based on the change in the state of charge of the battery pack or the change in the state of charge of multiple cells within the battery pack. If the state of charge of the battery pack increases, the battery pack is in a charging state; if the state of charge of the battery pack decreases, the battery pack is in a discharging state.

[0094] S132. Connect the cell with the highest state of charge in the battery pack to the equalization energy storage module through the equalization charging module, and equalize the cell with the highest state of charge in the battery pack according to the charging current of the battery pack.

[0095] The state of charge (SOC) of multiple cells within the battery pack is detected. The SOC of the cells can be obtained from the open-circuit voltage of each cell. The cell with the highest SOC in the battery pack is determined based on its SOC. For example, when determining the cell with the highest SOC, the cells can be sorted according to their SOC to obtain the cell with the highest SOC in the battery pack.

[0096] After identifying the cell with the highest state of charge (SOC) within the battery pack, the control module controls the balancing switch module to connect the cell with the SOC to the balancing charging module. For example, the control module generates a connection control signal, and the balancing switch module, based on this signal, connects the cell with the highest SOC to the balancing charging module. At this point, the cell with the highest SOC is connected to the balancing charging module via the balancing switch module, and subsequently to the balancing energy storage module.

[0097] When the cell with the highest state of charge (SOC) in the battery pack is connected to the balancing energy storage module, the control module controls the output of the balancing charging module based on the charging current, thereby balancing the SOC of multiple cells within the battery pack. The balancing current of the cell with the highest SOC is related to the charging current of the battery pack. When there is no charging current in the battery pack (i.e., the charging current is zero), the balancing charging module is turned off, and its output current is zero. When the charging current of the battery pack is not zero, the battery pack is actually charging, and the output current of the balancing charging module depends on the charging current of the battery pack; the output current of the balancing charging module is less than or equal to the charging current of the battery pack.

[0098] S133. Connect the cell with the highest state of charge in the battery pack to the equalization energy storage module through the equalization charging module to equalize the state of charge of multiple cells in the battery pack.

[0099] The control module determines the cell with the highest state of charge (SOC) within the battery pack by comparing the SOC of multiple cells. The control module then controls the balancing switch module to connect this SOC to the balancing charging module, effectively establishing a circuit between the SOC and the balancing charging module. At this point, the SOC is essentially connected in parallel with the balancing energy storage module. While discharging externally, the SOC also charges the balancing energy storage module through the balancing charging module. This increases the discharge current of the SOC and accelerates its SOC change, thereby achieving balancing of the multiple cells within the battery pack.

[0100] Figure 9 is a flowchart of another battery pack charge-discharge balancing method provided in an embodiment of this application. Optionally, based on the above embodiments, referring to Figure 9, the state of charge of multiple cells within the battery pack is balanced according to the charge-discharge state of the battery pack, including:

[0101] S141. Determine the charging / discharging state of the battery pack; if the battery pack is charging, execute S142; if the battery pack is discharging, execute S143.

[0102] For example, the state of charge / discharge of the battery pack can be obtained based on the change in the state of charge of the battery pack or the change in the state of charge of multiple cells within the battery pack. If the state of charge of the battery pack increases, the battery pack is in a charging state; if the state of charge of the battery pack decreases, the battery pack is in a discharging state.

[0103] S142. Determine whether the battery pack is in constant current charging mode; if the battery pack is in constant current charging mode, execute S1421; if the battery pack is not in constant current charging mode, execute S1422.

[0104] The battery pack offers two charging modes: constant current charging and constant voltage charging. In constant current charging, the charging current within the battery pack remains constant; in constant voltage charging, the charging voltage across the battery pack remains constant. When the battery pack is in constant current charging mode, the control module determines the cell with the lowest state of charge (SOC) by comparing the SOCs of multiple cells. The control module then controls the balancing switch module to connect the balancing discharge module to the cell with the lowest SOC, effectively establishing a circuit between the balancing discharge module and the cell with the lowest SOC, thus connecting the balancing energy storage module to the cell with the lowest SOC. When the battery pack is in constant voltage charging mode, the control module determines the cell with the lowest SOC and the cell with the highest SOC by comparing the SOCs of multiple cells. At this time, within a preset charging time, the control module controls the balancing switch module to connect the cell with the highest SOC to the balancing energy storage module through the balancing charging module, and controls the balancing energy storage module to switch from a discharging state to a charging state to store the energy output by the cell with the highest SOC. After the preset charging time has elapsed, the control module disconnects the cell with the highest state of charge from the balancing energy storage module and controls the balancing energy storage module to revert to a discharging state. The control module also connects the balancing energy storage module to the cell with the lowest state of charge via the balancing discharge module, allowing the balancing discharge module to charge the cell with the lowest state of charge, increasing the charging current and accelerating the change in state of charge of that cell.

[0105] S1421. Connect the equalization energy storage module to the cell with the lowest state of charge in the battery pack through the equalization discharge module, so as to equalize the state of charge of multiple cells in the battery pack.

[0106] The cell with the lowest state of charge is connected in parallel with the balancing energy storage module. The balancing energy storage module assists the cell with the lowest state of charge in charging through the balancing discharge module. At this time, the charging current of the cell with the lowest state of charge consists of the actual charging current of the cell with the lowest state of charge and the discharge current of the balancing energy storage module. As the charging current of the cell with the lowest state of charge increases, the state of charge of the cell with the lowest state of charge changes faster, thereby achieving the balancing of multiple cells in the battery pack.

[0107] S1422. Connect the cell with the highest state of charge in the battery pack to the cell with the lowest state of charge in the battery pack through the equalization charging module, the equalization energy storage module and the equalization discharging module, so as to equalize the state of charge of multiple cells in the battery pack.

[0108] The electrical energy of the cell with the highest state of charge in the battery pack is transferred to the cell with the lowest state of charge in the battery pack through the equalization charging module, equalization energy storage module and equalization discharging module, so as to achieve equalization of multiple cells in the battery pack.

[0109] S143. Connect the equalization energy storage module to the cell with the lowest state of charge in the battery pack through the equalization discharge module, and equalize the cell with the lowest state of charge in the battery pack according to the discharge current of the battery pack.

[0110] The state of charge (SOC) of multiple cells within the battery pack is detected. The SOC of the cells can be obtained from the open-circuit voltage of each cell. The cell with the lowest SOC in the battery pack is determined based on the SOC of the multiple cells. For example, when determining the cell with the highest SOC, the cells can be sorted according to their SOC to obtain the cell with the lowest SOC.

[0111] After identifying the cell with the lowest state of charge (SOC) within the battery pack, the control module controls the balancing switch module to establish a connection between that cell and the balancing discharge module. For example, the control module generates a connection control signal, and the balancing switch module, based on this signal, establishes a connection between the cell with the lowest SOC and the balancing discharge module. At this point, the cell with the lowest SOC is connected to the balancing discharge module via the balancing switch module, thereby establishing a connection between the balancing energy storage module and the cell with the lowest SOC within the battery pack.

[0112] When the cell with the lowest state of charge (SOC) in the battery pack is connected to the balancing energy storage module, the control module controls the output of the balancing discharge module based on the discharge current, thereby balancing the SOC of multiple cells in the battery pack. The current of the cell with the lowest SOC during balancing is related to the discharge current of the battery pack. When there is no discharge current in the battery pack, that is, when the discharge current is zero, the balancing discharge module is turned off, and its output current is zero. When the charging current of the battery pack is not zero, the battery pack is actually discharging. In this case, the output current of the balancing discharge module depends on the discharge current of the battery pack, and the output current of the balancing discharge module is less than or equal to the discharge current of the battery pack.

[0113] This application also provides a battery pack. The battery pack includes: a plurality of cells connected in series and the battery pack charge / discharge equalization device provided in any of the above embodiments. The battery pack provided in this embodiment has the beneficial effects of the battery pack charge / discharge equalization device provided in any of the above embodiments, which will not be elaborated further here.

[0114] The various processes shown above can be used to rearrange, add, or delete steps. For example, the multiple steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

Claims

1. A battery pack charge-discharge equalization method, applied to a battery pack charge-discharge equalization device, the battery pack charge-discharge equalization device comprising: Balanced energy storage module; The battery pack charge / discharge equalization method includes: Obtain the charging and discharging status of the battery pack and the charging and discharging status of the equalization energy storage module; In response to the equalization energy storage module being in a charging state, the cells with the largest state of charge in the battery pack are balanced according to the charging and discharging state of the battery pack, so as to balance the state of charge of multiple cells in the battery pack. In response to the equalization energy storage module being in a discharging state, the state of charge of the multiple cells in the battery pack is equalized according to the charging and discharging state of the battery pack.

2. The method according to claim 1, wherein, The battery pack charge / discharge equalization device further includes: an equalization charging module; the step of equalizing the state of charge of the cells with the highest state of charge in the battery pack according to the charge / discharge state of the battery pack, so as to equalize the state of charge of multiple cells in the battery pack, includes: In response to the battery pack being in a charging state, the cell with the largest state of charge in the battery pack is connected to the equalization energy storage module through the equalization charging module, and the cell with the largest state of charge in the battery pack is equalized according to the charging current of the battery pack. In response to the battery pack being in a discharging state, the cell with the highest state of charge in the battery pack is connected to the equalization energy storage module through the equalization charging module to equalize the state of charge of the multiple cells in the battery pack.

3. The method according to claim 2, wherein, The battery pack charge / discharge balancing device further includes: a balancing switch module; the step of connecting the cell with the highest state of charge in the battery pack to the balancing energy storage module through the balancing charging module, and balancing the cell with the highest state of charge in the battery pack according to the charging current of the battery pack, includes: The cell with the largest state of charge in the battery pack is determined based on the state of charge of the plurality of cells in the battery pack. The equalization switch module controls the connection between the battery cell with the highest state of charge in the battery pack and the equalization charging module. The output of the equalization charging module is controlled according to the charging current to balance the state of charge of the multiple cells in the battery pack.

4. The method according to claim 1, wherein, The battery pack charge / discharge balancing device further includes: a balancing charging module and a balancing discharging module; the step of balancing the state of charge of the multiple cells in the battery pack according to the charge / discharge state of the battery pack includes: In response to the battery pack being in a charging state, determine whether the battery pack is in a constant current charging mode; In response to the battery pack being in the constant current charging mode, the equalization energy storage module is connected to the cell with the lowest state of charge in the battery pack through the equalization discharge module, so as to equalize the state of charge of the multiple cells in the battery pack. In response to the battery pack not being in the constant current charging mode, the cell with the largest state of charge in the battery pack is connected to the cell with the smallest state of charge in the battery pack through the equalization charging module, the equalization energy storage module and the equalization discharging module, so as to equalize the state of charge of the multiple cells in the battery pack. In response to the battery pack being in a discharging state, the equalization energy storage module is connected to the cell with the lowest state of charge in the battery pack through the equalization discharge module, and the cell with the lowest state of charge in the battery pack is equalized according to the discharge current of the battery pack.

5. The method according to claim 4, wherein, The battery pack charge / discharge balancing device further includes: a balancing switch module; the step of connecting the balancing energy storage module to the cell with the lowest state of charge in the battery pack through the balancing discharge module, and balancing the cell with the lowest state of charge in the battery pack according to the discharge current of the battery pack, includes: The cell with the lowest state of charge in the battery pack is determined based on the state of charge of the plurality of cells in the battery pack. The equalization switch module controls the connection between the cell with the lowest state of charge in the battery pack and the equalization discharge module. The output of the equalization discharge module is controlled according to the discharge current to equalize the state of charge of the multiple cells in the battery pack.

6. A battery pack charge-discharge equalization device, wherein the battery pack includes a plurality of cells connected in series; the battery pack charge-discharge equalization device includes: Equalization switch module, equalization charging module, equalization discharging module, equalization energy storage module, and control module; Multiple battery cells are connected to the equalization charging module and the equalization discharging module through the equalization switch module. The multiple battery cells are also connected to the control module. The equalization charging module and the equalization discharging module are both connected to the equalization energy storage module. The equalization switch module, the equalization charging module, the equalization discharging module, and the equalization energy storage module are also connected to the control module. The equalization switch module is configured to control the connection between the plurality of battery cells and the equalization charging module or the equalization discharging module; the equalization charging module is configured to charge the equalization energy storage module; the equalization discharging module is configured to discharge the equalization energy storage module; the equalization energy storage module is configured to equalize the plurality of battery cells through charging and discharging; the control module is configured to execute the battery pack charge-discharge equalization method as described in any one of claims 1 to 5.

7. The apparatus according to claim 6, wherein, The equalization switch module includes: an equalization switch unit, a charging switch unit, and a discharging switch unit; The plurality of battery cells are all connected to the equalization switch unit. The first and second ends of the charging switch unit are both connected to the equalization switch unit. The first end of the discharging switch unit is connected to the first end of the charging switch unit. The second end of the discharging switch unit is connected to the second end of the charging switch unit. The third and fourth ends of the charging switch unit are both connected to the equalization charging module. The third and fourth ends of the discharging switch unit are both connected to the equalization discharging module. The equalization switch unit is configured to control the connection between the plurality of battery cells and the charging switch unit or the discharging switch unit; the charging switch unit is configured to change the polarity of the plurality of battery cells and control the connection between the equalization switch unit and the equalization charging module; the discharging switch unit is configured to change the polarity of the plurality of battery cells and control the connection between the equalization switch unit and the equalization discharging module.

8. The apparatus according to claim 7, wherein, The equalization switching unit includes: a plurality of first switches and a plurality of second switches; The first ends of the plurality of first switches are connected to the first end of the charging switch unit, the first ends of the plurality of second switches are connected to the second end of the charging switch unit, the second ends of the plurality of first switches and the second ends of the plurality of second switches are connected to the plurality of battery cells in an alternating manner, and the two ends of each battery cell are respectively connected to the first switch and the second switch.

9. The apparatus according to claim 7, wherein, The charging switch unit includes: a first charging switch, a second charging switch, a first charging reversing switch, and a second charging reversing switch; The first end of the first charging switch serves as the first end of the charging switch unit, the second end of the first charging switch serves as the third end of the charging switch unit, the first end of the second charging switch serves as the second end of the charging switch unit, the second end of the second charging switch serves as the fourth end of the charging switch unit, the first end of the first charging reversing switch is connected to the first end of the first charging switch, the second end of the first charging reversing switch is connected to the second end of the second charging switch, the first end of the second charging reversing switch is connected to the first end of the second charging switch, and the second end of the second charging reversing switch is connected to the second end of the first charging switch.

10. The apparatus according to claim 7, wherein, The discharge switch unit includes: a first discharge switch, a second discharge switch, a first discharge reversing switch, and a second discharge reversing switch; The first end of the first discharge switch serves as the first end of the discharge switch unit, the second end of the first discharge switch serves as the third end of the discharge switch unit, the first end of the second discharge switch serves as the second end of the discharge switch unit, the second end of the second discharge switch serves as the fourth end of the discharge switch unit, the first end of the first discharge reversing switch is connected to the first end of the first discharge switch, the second end of the first discharge reversing switch is connected to the second end of the second discharge switch, the first end of the second discharge reversing switch is connected to the first end of the second discharge switch, and the second end of the second discharge reversing switch is connected to the second end of the first discharge switch.

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