Battery pack parallel connection method, battery management system, battery pack and electric equipment

Abstract

The embodiment of the invention relates to the technical field of batteries, for example, relates to a battery pack parallel connection method, a battery management system, a battery pack, electric equipment and a storage medium. The battery pack parallel connection method comprises the following steps: in response to the condition that a first battery pack meets a first parallel connection condition and the first battery pack is in a charging state, controlling a switch on a discharging loop to be in an off state, and performing charging parallel connection by the first battery pack. Or, in response to the condition that the first battery pack meets the first parallel connection condition and the first battery pack is in the discharging state, the switch on the charging loop is controlled to be in the off state, and the first battery pack executes discharging parallel connection. According to the embodiment of the invention, the discharging loop is in the off state when the battery pack is charged, and the charging loop is in the off state when the battery pack is discharged, so that the ring current generated by the discharging loop between the battery packs during charging and the ring current generated by the charging loop during discharging can be reduced, and the ring current between the battery packs can be reduced; and the safety of the battery pack is improved.

Description

Battery pack parallel connection method, battery management system, battery pack and electrical equipment Technical Field

[0001] The embodiments of the present application relate to the field of battery technology, and in particular to a battery pack parallel connection method, a battery management system, a battery pack, an electrical device, and a storage medium. Background Art

[0002] When powering electrical devices, battery packs can be connected in parallel to increase battery capacity and extend the life of the device. For example, a battery-powered two-wheeled vehicle can use parallel battery packs to increase the vehicle's range.

[0003] Differences in charge and discharge between battery packs, as well as differences in leakage current from the cells when not in use, can lead to voltage inconsistencies between packs. This can easily cause circulating currents when the packs are connected in parallel. Excessive circulating currents can cause excessive current in a pack, triggering current limiting protection and potentially damaging the pack.

[0004] In the current battery pack parallel connection scheme, it is easy to generate large circulating current between the battery packs, causing battery pack overcurrent.

[0005] Summary of the Invention

[0006] Embodiments of the present application provide a battery pack parallel connection method, a battery management system, a battery pack, an electrical device, and a storage medium, which can reduce the circulation current between battery packs.

[0007] In a first aspect, embodiments of the present application provide a method for connecting battery packs in parallel, the method comprising: in response to a first battery pack satisfying a first parallel condition and being in a charging state, controlling a switch on a discharge circuit to be in an off state, and causing the first battery pack to perform charging in parallel. Alternatively, in response to the first battery pack satisfying the first parallel condition and being in a discharging state, controlling a switch on the charging circuit to be in an off state, and causing the first battery pack to perform discharging in parallel. The first parallel condition may include operating data of the first battery pack satisfying the parallel condition, where the operating data includes at least one of voltage data, current data, SOC data, temperature data, and communication status.

[0008] In some embodiments, the first parallel condition includes at least one of the following:

[0009] (1) The voltage difference between the voltage of the first battery pack and the first voltage is within a first voltage difference range. When the first battery pack is in a charging state, the first voltage is the minimum voltage among the battery packs; when the first battery pack is in a discharging state, the first voltage is the maximum voltage among the battery packs.

[0010] (2) The difference between the SOC of the first battery pack and the first SOC is within a first SOC range. When the first battery pack is in a charging state, the first SOC is the minimum SOC among the battery packs; when the first battery pack is in a discharging state, the first SOC is the maximum SOC among the battery packs.

[0011] (3) The temperature of the first battery pack is within a first temperature range.

[0012] (4) The first charging current rate is within a first current rate range, or the first discharging current rate is within a second current rate range. The first charging current rate is the maximum charging current rate of the battery pack connected in parallel, and the first discharging current rate is the maximum discharging current rate of the battery pack connected in parallel.

[0013] (5) Communication status of the first battery pack. The communication status of the first battery pack is used to indicate that the first battery pack has successfully communicated with at least one of the parallel-connected battery packs.

[0014] In some embodiments, controlling the switch on the discharge circuit to be in an off state and the first battery pack to perform parallel charging includes: controlling the switch on the discharge circuit of the first battery pack and / or each parallel battery pack to be in an off state and the first battery pack to perform parallel charging.

[0015] Controlling the first battery pack and / or controlling the switches on the discharge circuits of each parallel-connected battery pack to be in an off state can cut off the parallel discharge connection between the first battery pack and the parallel-connected battery packs, thereby reducing the circulating current generated between the battery packs through the discharge circuit during charging.

[0016] In some embodiments, controlling the switch on the charging circuit to be in an off state, and the first battery pack to perform discharge in parallel, includes: controlling the switch on the charging circuit of the first battery pack and / or each parallel battery pack to be in an off state, and the first battery pack to perform discharge in parallel.

[0017] Controlling the first battery pack and / or controlling the switches on the charging circuits of each parallel battery pack to be in an off state can cut off the parallel charging connection between the first battery pack and the parallel battery packs, thereby reducing the circulating current generated between the battery packs through the charging circuit during discharge.

[0018] In some embodiments, in response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a charging state, controlling a switch on a discharge circuit to be in an open state, and the first battery pack performing parallel charging includes: in response to the first battery pack meeting the first parallel connection condition, the first battery pack sending a parallel connection request instruction; in response to the first battery pack being in a charging state, opening the switch on the discharge circuit of the first battery pack and closing the charging switch on the charging circuit of the first battery pack.

[0019] In some embodiments, in response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a charging state, controlling a switch on a discharge circuit to be in an open state, and the first battery pack performing parallel charging, includes: in response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a charging state, controlling a switch on a discharge circuit to be in an open state, and the first battery pack performing parallel charging, including: in response to the first battery pack meeting the first parallel connection condition, the first battery pack sending a parallel connection request instruction. The switch on the discharge circuit of the first battery pack is in an open state, and in response to the first battery pack being in a charging state, closing a charging switch on the charging circuit of the first battery pack.

[0020] In some embodiments, in response to a first battery pack meeting a first parallel connection condition and being in a discharging state, controlling a switch on a charging circuit to be in an off state, so that the first battery pack performs a discharging parallel connection, includes: in response to the first battery pack meeting the first parallel connection condition, the first battery pack sending a parallel connection request instruction; in response to the first battery pack being in a discharging state, disconnecting the switch on the charging circuit of the first battery pack and closing the discharge switch on the discharge circuit of the first battery pack.

[0021] In some embodiments, in response to a first battery pack meeting a first parallel connection condition and being in a discharging state, controlling a switch on a charging circuit to be in an off state, so that the first battery pack performs a discharge parallel connection, includes: in response to the first battery pack meeting the first parallel connection condition, the first battery pack sending a parallel connection request instruction; the switch on the charging circuit of the first battery pack is in an off state; and in response to the first battery pack being in a discharging state, closing a discharge switch on the discharge circuit of the first battery pack.

[0022] The parallel connection request instruction is used to notify other battery packs to join the electrical device, enabling roughly synchronous parallel operation of the first battery pack and the other battery packs. After receiving the parallel connection request instruction from the other battery packs, the battery pack can also execute the parallel connection judgment logic. This allows the battery pack to periodically execute the parallel connection judgment logic at longer intervals, reducing the amount of computation required by the battery pack. Furthermore, the parallel connection request instruction can also carry information indicating the charge and discharge status of the electrical device. Even if the battery pack cannot receive the charging signal from the charger, it can still correct its operating status using the parallel connection request instruction, reducing the possibility of the battery pack misjudging its operating status.

[0023] In some embodiments, the battery pack parallel connection method further includes: in response to the second battery pack receiving the parallel connection request instruction, disconnecting a discharge switch on the charging circuit of the second battery pack, where the second battery pack is the battery pack already connected in parallel. Disconnecting the discharge switch on the charging circuit of the battery pack already connected in parallel can disconnect the circulating current path of the battery pack already connected in parallel, thereby reducing the circulating current.

[0024] In some embodiments, closing the charging switch on the charging circuit of the first battery pack includes: closing the charging switch in response to receiving first information. The first information indicates that a discharge switch on the charging circuit of the second battery pack is in an open state, and the second battery pack is a parallel-connected battery pack. The first information ensures that the first battery pack closes the charging switch on the charging circuit only after the circulating current path of the parallel-connected battery pack is disconnected, thereby reducing circulating current.

[0025] In some embodiments, in response to a first battery pack meeting a first condition, a discharge switch on the first battery pack charging circuit is closed, and / or in response to a second battery pack meeting the first condition, a discharge switch on the second battery pack charging circuit is closed. The first condition includes at least one of the following:

[0026] (1) The charging current of the battery pack is greater than or equal to the first current threshold.

[0027] (2) The charging current of the battery pack is less than the first current threshold, and the voltage difference between the sum of the voltage of the battery pack and the second voltage is within the second voltage difference range.

[0028] The second voltage is the minimum voltage in each battery pack. Setting the first condition can limit the circulating current, and the circulating current path is closed only when the risk of a large circulating current is small.

[0029] In some embodiments, the battery pack parallel connection method further includes: in response to the first battery pack satisfying a first circulation condition, disconnecting a charging switch and a discharging switch on the charging circuit of the first battery pack. The first circulation condition includes that the absolute value of the difference between the current rate of the first battery pack and the first current rate is greater than or equal to a first current rate threshold. The first current rate is the maximum charging current rate among all the parallel-connected battery packs. The current rate of the first battery pack includes a charging current rate or a discharging current rate. The charging current rate is a positive value, and the discharging current rate is a negative value.

[0030] After the charging switch and the discharging switch on the battery pack charging circuit are closed, the circulating current risk is also judged to reduce the circulating current risk.

[0031] In some embodiments, the battery pack parallel connection method further includes: in response to the second battery pack receiving a parallel connection request, disconnecting a charging switch on a discharge circuit of the second battery pack. The second battery pack is a battery pack already connected in parallel. Disconnecting the charging switch on the discharge circuit of the battery pack already connected in parallel disconnects the circulating current path of the battery pack already connected in parallel, thereby reducing the circulating current.

[0032] In some embodiments, closing the discharge switch on the discharge circuit of the first battery pack includes: closing the discharge switch in response to receiving second information. The second information indicates that a charging switch on the discharge circuit of the second battery pack is in an off state, and the second battery pack is a parallel-connected battery pack. The second information ensures that the first battery pack closes the discharge switch on the discharge circuit only after the circulating current path of the parallel-connected battery pack is disconnected, thereby reducing the circulating current.

[0033] In some embodiments, in response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a discharging state, controlling the switch on the charging circuit of the first battery pack to be in an open state, and the first battery pack performing discharge parallel connection, further comprising: in response to the first battery pack meeting the second condition, closing the charging switch on the discharging circuit of the first battery pack, and / or, in response to the second battery pack meeting the second condition, closing the charging switch on the charging circuit of the second battery pack. The second condition includes at least one of the following:

[0034] (1) The discharge current of the battery pack is greater than or equal to the second current threshold;

[0035] (2) The discharge current of the battery pack is less than the second current threshold, and the voltage difference between the battery pack voltage and the third voltage is within the third voltage difference range.

[0036] The third voltage is the maximum voltage of each battery pack. Setting the second condition can limit the circulating current, and the circulating current path is closed only when the risk of large circulating current is small.

[0037] In some embodiments, in response to the first battery pack satisfying a first parallel connection condition and the first battery pack being in a discharging state, controlling a switch on the charging circuit of the first battery pack to be in an off state, and the first battery pack performing a discharge parallel connection, further comprising: in response to the first battery pack satisfying a second circulating current condition, disconnecting the charging switch and the discharging switch on the discharging circuit of the first battery pack. The second circulating current condition includes that the absolute value of the difference between the current rate of the first battery pack and the second current rate is greater than or equal to a second current rate threshold. The second current rate is the maximum discharge current rate among all the parallel-connected battery packs. The current rate of the first battery pack includes a charging current rate or a discharging current rate, with the charging current rate being a positive value and the discharging current rate being a negative value.

[0038] After the charging switch and the discharging switch on the battery pack discharge circuit are closed, the circulating current risk is also judged, which can reduce the circulating current risk.

[0039] In some embodiments, the battery pack parallel connection method further includes: detecting the on / off status of the charging switch and / or the discharging switch on the battery pack charging circuit and sending a third information; and / or detecting the on / off status of the charging switch and / or the discharging switch on the battery pack discharging circuit and sending a fourth information. The third information is used to indicate the on / off status of the charging switch and / or the discharging switch on the charging circuit, and the fourth information is used to indicate the on / off status of the charging switch and / or the discharging switch on the discharge circuit. The third and fourth information can be referred to as checkback information. By sending the checkback information through the checkback switch, the parallel connection time of the battery pack can be accelerated as a whole, simplifying the parallel connection process.

[0040] In some embodiments, the battery pack parallel connection method further includes: a switch on the discharge circuit responding to a control signal to extend a first time period for switching on and off, and a switch on the charge circuit responding to a control signal to extend a second time period for switching on and off. Extending the time period after receiving the control signal before switching on or off ensures that the switches on the charge and discharge circuits are properly closed or opened, thereby enhancing the stability of the parallel connection of the battery packs.

[0041] In a second aspect, an embodiment of the present application also provides a battery management system, comprising at least one processor and a memory, wherein the memory is communicatively connected to the at least one processor, and the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the above-mentioned method.

[0042] In a third aspect, an embodiment of the present application further provides a battery pack comprising the above-mentioned battery management system.

[0043] In a fourth aspect, an embodiment of the present application further provides an electrical device, comprising a load and the above-mentioned battery pack, wherein the battery pack is used to power the load.

[0044] In a fifth aspect, an embodiment of the present application further provides a storage medium storing computer-executable instructions. When the computer-executable instructions are executed by a machine, the machine executes the above-mentioned method.

[0045] Compared to the prior art, the embodiments of the present application disconnect the discharge circuit when the battery pack is charging, and disconnect the charging circuit when the battery pack is discharging. This can reduce the circulating current generated between the battery packs through the discharge circuit during charging, and the circulating current generated through the charging circuit during discharging, thereby reducing the circulating current between the battery packs and improving the safety of the battery pack. When the battery pack is discharging, the switch on the charging circuit is controlled to be in the off state, which can reduce the voltage at the charging port. When the charging circuits of the first battery pack and all the parallel battery packs are disconnected, the charging port can be de-energized. This improves the safety of the charging port and reduces the risk of electric shock from contact with the charging port.

[0046] Furthermore, when the device switches from discharging to charging, this embodiment can directly control the switch on the discharge circuit to the off state, enabling parallel charging. This allows for convenient transitions between operating states, eliminating the need to shut down and restart the device, or to unparallel each battery pack and then re-parallelize it, simplifying the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] One or more embodiments are exemplarily described by the figures in the accompanying drawings, which are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0048] Figures 1a-1c are schematic structural diagrams of electrical equipment according to an embodiment of the present application;

[0049] Figures 2a-2c and 3 are schematic structural diagrams of a battery pack according to an embodiment of the present application;

[0050] 4a-4c are working state diagrams of the discharge circuit of the battery pack according to an embodiment of the present application;

[0051] Figures 5a-5c are working state diagrams of the charging circuit of the battery pack according to an embodiment of the present application;

[0052] Figures 6a-6d are schematic diagrams of the switch structure of the charge and discharge control part of the BMS according to an embodiment of the present application;

[0053] FIG7 is a schematic diagram of the hardware structure of the controller in the BMS embodiment of the present application;

[0054] FIG8 is a flow chart of an embodiment of a method for connecting battery packs in parallel according to the present application;

[0055] FIG9 is a schematic diagram of the switch structure of the charge and discharge control part of the BMS according to an embodiment of the present application;

[0056] FIG10 is a flow chart of charging in one embodiment of the battery pack parallel connection method of the present application;

[0057] FIG11 is a flow chart of discharging in one embodiment of the battery pack parallel connection method of the present application;

[0058] Figures 12a to 12d are schematic diagrams of the working states of each stage during charging in one embodiment of the battery pack parallel connection method of the present application;

[0059] FIG13 is a schematic diagram of the interactive process of charging the battery packs in parallel according to an embodiment of the present application;

[0060] Figures 14a to 14d are schematic diagrams of the working states of each stage during charging in one embodiment of the battery pack parallel connection method of the present application;

[0061] FIG15 is a schematic diagram of the interactive process during discharge of a battery pack in parallel according to an embodiment of the present application;

[0062] FIG16 is a schematic diagram of the interactive process when charging the battery packs in parallel according to an embodiment of the present application. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and detailedly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. The technical features involved in the various embodiments of the present application described below do not conflict with each other and can be combined with each other.

[0064] In addition, although the functional modules are divided in the device schematics and the logical order is shown in the flowcharts, in some cases, the modules may be divided differently from those in the device, or the steps may be performed in an order different from that shown in the flowcharts.

[0065] When an element is referred to as being “connected to” another element, it can be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0066] In some electrical devices, using parallel-connected battery packs can increase battery capacity, thereby extending the device's operating time. Figure 1a shows the battery-related structure of an electrical device 1000. The device 1000 includes N parallel-connected battery packs 100, designated Battery Pack 1 through Battery Pack N. N is a natural number ≥ 2, and each battery pack 100 serves as an energy module for the device.

[0067] The electrical device 1000 may be an electric vehicle, or other equipment that can be powered by a parallel battery pack, such as an electric two-wheeled vehicle, an electric three-wheeled vehicle, etc.

[0068] The power-consuming device 1000 may include a charging and discharging port, through which the battery pack 100 of the power-consuming device 1000 can be charged and discharged. In one embodiment of the present application, the charging and discharging ports of the power-consuming device 1000 may adopt a different port solution. This different port solution can be understood as the charging port and the discharging port being different ports. In one specific implementation, the charging and discharging ports may be different connection ports on a connector.

[0069] As shown in Figure 1a, each battery pack shares a single negative port. That is, the negative charging port C- and the negative discharge port P- of the power-consuming device 1000 are the same port on the connector, while the positive charging port C+ and the positive discharge port P+ of the power-consuming device 1000 are different ports on the connector. It is understood that in the embodiment shown in Figure 1a, the negative charging port C- and the negative discharge port P- are the same port, while the positive charging port C+ and the positive discharge port P+ are different ports.

[0070] 1b , the discharge port of the electrical device 1000 is used to electrically connect to a load 200 of the electrical device 1000 to supply power to the load 200. For example, in the case where the electrical device is an electric vehicle, the load may be electrical components on the electric vehicle, such as a motor, an instrument, or a vehicle controller.

[0071] The charging port of the electric device 1000 is used to electrically connect to the charger 2000 , and the charger is used to connect to an external power source to charge the electric device 1000 , specifically the battery pack 100 .

[0072] The battery pack 100 may be provided with corresponding electrical connection terminals (e.g., connectors or connection harnesses) for respectively electrically connecting to the charging and discharging ports of the power-consuming device 1000. In an embodiment where the power-consuming device 1000 has a port C+, a port P+, and a port P-(C-), correspondingly, referring to FIG. 2a , the battery pack 100 has a C+ terminal, a P+ terminal, and a P-(C-) terminal, for respectively electrically connecting to the C+, P+, and P-(C-) ports of the power-consuming device 1000.

[0073] In other embodiments of the power-consuming device 1000 with different charging and discharging ports, each battery pack may share a common positive terminal, a single positive terminal P+ (C+). The positive charging port C+ and the positive discharging port P+ of the power-consuming device 1000 are the same port on the connector, while the negative charging port C- and the negative discharging port P- of the power-consuming device 1000 are different ports on the connector.

[0074] In the embodiment where the electric device 1000 has a port P+(C+), a port C- and a port P-, correspondingly, please refer to Figure 2b, the battery pack 100 has a P+(C+) terminal, a C- terminal and a P- terminal, which are used to electrically connect to the port P+(C+), port C- and port P- of the electric device 1000, respectively.

[0075] In other embodiments with different charging and discharging ports, the battery packs may not share ports. The charging port includes port C+ and port C-, and the discharging port includes port P+ and port P-.

[0076] In the embodiment where the electrical device 1000 has port C+, port C-, port P+ and port P-, correspondingly, please refer to Figure 2c, the battery pack 100 respectively has a C+ terminal, a C- terminal, a P+ terminal and a P- terminal, which are used to electrically connect to the port C+, port C-, port P+ and port P- of the electrical device respectively.

[0077] Those skilled in the art will appreciate that the above is merely an example of the connection relationship between the battery pack and the charging port and the discharge port of the electrical device. In other embodiments, other connection methods may also be used. For example, the battery pack has a C+ terminal, a C- terminal, a P+ terminal, and a P- terminal as shown in FIG2c. The C+ terminal may be electrically connected to the port C+, the P+ terminal may be electrically connected to the port P+, and the C- terminal and the P- terminal may be electrically connected to the port P-(C-). For another example, the battery pack has a C+ terminal, a P+ terminal, and a P-(C-) terminal as shown in FIG2a. The C+ terminal may be electrically connected to the port C+, the P+ terminal may be electrically connected to the port P+, and the P-(C-) terminal may be electrically connected to the port C- and the port P-, respectively.

[0078] The charging port and / or the discharging port may be configured as a connection port or connector. In other embodiments, since the discharging port does not need to be connected to an external device but only needs to be connected to a load within the electrical device, a connection port or connector may not be required, and the battery pack may be directly electrically connected to the corresponding load using a connecting harness.

[0079] 1 c , 2 a - 2 c , and 3 , each battery pack 100 includes a battery management system (BMS) 10 and an energy module 20 (eg, a cell module).

[0080] The energy module 20 includes multiple battery cells for storing and providing electrical energy. The multiple battery cells can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to the electrical connection of the battery cells being connected in both series and parallel. The BMS 10 is used to detect, manage, control, and / or protect the energy module 20. For example, the BMS 10 can detect operating data of the energy module 20 and / or the communication status of the battery pack, such as voltage, current, temperature, and State of Charge (SOC) data.

[0081] The BMS10 on each battery pack 100 can be communicatively connected to each other. For example, as shown in FIG1c , each BMS10 is communicatively connected via a communication bus 300 . Through the communication bus 300 , each battery pack 100 can exchange instructions and data (such as the aforementioned operating data).

[0082] In some embodiments, the charger can also be communicatively connected with the BMS10 of each battery pack, for example, by being communicatively connected with the BMS10 of each battery pack through a communication bus, and sending a charging signal to each battery pack. The charging signal can be used to instruct the battery pack to perform a charging operation.

[0083] Among them, the communication bus 300 is such as a CAN communication bus, an RS485 communication bus, etc. In addition, the BMS10 and the charger and the BMS10 can also be connected through other wired or wireless methods, such as Wi-Fi communication, mobile communication technology or Bluetooth communication technology.

[0084] The energy modules 20 of each battery pack 100 can be electrically connected in parallel to supply power to the electrical device 1000 , thereby increasing the battery capacity of the electrical device 1000 .

[0085] In some embodiments, the energy module 20 can be connected in parallel with other energy modules through the BMS 10. Electrical connection terminals for connecting to the charging and discharging ports of electrical equipment (such as the C+ terminal, P+ terminal, and P-(C-) terminal in Figure 2a) can be provided on the BMS 10. One end of the electrical connection terminal is used to connect to the energy module 20, and the other end is used to connect to the charging and discharging ports. By connecting the electrical connection terminals on the BMS 10 to the corresponding charging and discharging ports, the energy modules 20 are connected in parallel.

[0086] The C+, P+, and P+(C+) terminals of the electrical connection terminals are used to connect to the positive electrode of the energy module 20, and the C-, P-, and P-(C-) terminals are used to connect to the negative electrode of the energy module 20. The electrical connection terminals can be configured as connection ports or connectors, or can also be a section of connecting wiring harness.

[0087] In some specific implementations of the present application, the BMS 10 may be presented in the form of a printed circuit board. A switch may also be provided on the BMS 10 circuit board, for example, between the energy module 20 and the electrical connection terminal. The BMS 10 may control the switch to integrate the energy module 20 into or disconnect the energy module 20 from the electrical device 1000. When the BMS 10 controls the switch to establish a connection between the energy module 20 and the electrical connection terminal, the energy module 20 is integrated into the electrical device 1000. When the BMS 10 controls the switch to disconnect the energy module 20 from the electrical connection terminal, the energy module 20 is disconnected from the electrical device 1000.

[0088] For the convenience of description below, the integration or disconnection of the energy module 20 into or out of the electrical equipment is referred to as the integration or disconnection of the battery pack into or out of the electrical equipment, and the parallel connection of the energy modules 20 is referred to as the parallel connection of the battery packs.

[0089] In the charging and discharging differential port scheme, different circuits can be used to charge and discharge the battery pack 100, respectively. The charging circuit is used to charge the battery pack 100, and the discharging circuit is used to discharge the battery pack 100. The charging circuit is electrically connected to the charging port of the electrical device, and the discharging circuit is electrically connected to the discharging port of the electrical device.

[0090] Switches may be provided on the charging circuit and the discharging circuit respectively. For example, at least one switch may be provided on the charging circuit to control the on and off of the charging circuit, and at least one switch may be provided on the discharging circuit to control the on and off of the discharging circuit.

[0091] By closing or opening the switch on the BMS 10, the battery pack 100 is connected to or disconnected from the electrical device 1000. When the BMS 10 controls the switch to conduct the charging circuit, the battery pack is connected to the electrical device and the battery pack is "charged in parallel". When the BMS 10 controls the switch to conduct the discharging circuit, the battery pack is connected to the electrical device and the battery pack is "discharged in parallel".

[0092] When the BMS10 controls the switch to disconnect the charging circuit, the "charging parallel" of the battery pack is disconnected, and the connection between the battery pack and the charging port is disconnected. When the BMS10 controls the switch to disconnect the discharging circuit, the "discharging parallel" of the battery pack is disconnected, and the connection between the battery pack and the discharge port is disconnected.

[0093] Figure 3 shows a structure of the charge and discharge control part of the BMS 10. It is understandable that the figure only shows the switch structure of the charge and discharge control part of the BMS, and does not show other structures such as the main control part and the detection part.

[0094] In the embodiment shown in Figure 3, the discharge circuit of BMS10 includes a charging switch CHG1 and a discharging switch DSG1 connected in series. In one specific embodiment, the charging switch CHG1 and the discharging switch DSG1 may be field-effect transistors, with the charging switch CHG1 including a body diode D1 and the discharging switch DSG1 including a body diode D2. In other embodiments, the charging switch CHG1 is connected in parallel with a diode D1, and the discharging switch DSG1 is connected in parallel with a diode D2, with diodes D1 and D2 sharing a common cathode. The charging switch CHG1, the discharging switch DSG1, the diode D1, and the diode D2 may serve as part of the discharge circuit, and the charging switch CHG1 and the discharging switch DSG1 are used to control the operating state of the discharge circuit.

[0095] Referring to Figure 4a , when discharge switch DSG1 is closed and charge switch CHG1 is open, the discharge path of energy module 20 is open, and energy module 20 can discharge to the load through this discharge path and discharge ports P+ and P- (C-). The current direction is: anode of energy module 20 → diode D1 → discharge switch DSG1 → P+ → load (not shown) → P- (C-) → cathode of energy module 20.

[0096] Referring to Figure 4b , when the discharge switch DSG1 is off and the charging switch CHG1 is closed, the circulation path of the energy module 20 is open. When the energy module 20 is connected in parallel with other energy modules and the voltage of the other energy modules is higher than that of the energy module 20, the other energy modules 20 can charge the energy module 20 through this circulation path and the discharge ports P+ and P-(C-). The current direction is: positive electrode of other energy module → P+ → diode D2 → charging switch CHG1 → positive electrode of energy module 20 → negative electrode of energy module 2020 → P-(C-) → negative electrode of other energy module.

[0097] Referring to FIG. 4 c , when the discharge switch DSG1 and the charge switch CHG1 are both closed, the discharge path and the circulation path are both conductive, and current can flow in two directions.

[0098] When the discharge switch DSG1 and the charge switch CHG1 are both turned off, the discharge path and the circulation path are both disconnected, and no current flows in the circuit.

[0099] The charging circuit of BMS10 may include a charging switch CHG2 and a discharging switch DSG2 connected in series. In one specific embodiment, the charging switch CHG2 and the discharging switch DSG2 may be field-effect transistors. The charging switch CHG2 includes a body diode D3, and the discharging switch DSG2 includes a body diode D4. In other embodiments, the charging switch CHG2 is connected in parallel with a diode D3, and the discharging switch DSG2 is connected in parallel with a diode D4, with diodes D3 and D4 sharing a common cathode. The charging switch CHG2, the discharging switch DSG2, the diode D3, and the diode D4 may serve as part of the charging circuit, and the charging switch CHG2 and the discharging switch DSG2 are used to control the operating state of the charging circuit.

[0100] Referring to Figure 5a , when the charging switch CHG2 is closed and the discharging switch DSG2 is open, the charging path of the energy module 20 is open, and the external power supply can charge the energy module 20 through this charging path and the charging ports C+ and P- (C-). The current direction is: external power supply positive electrode → C+ → diode D4 → charging switch CHG2 → energy module 20 positive electrode → energy module 20 negative electrode → P- (C-) → external power supply negative electrode.

[0101] Referring to Figure 5b , when the charging switch CHG2 is off and the discharging switch DSG2 is closed, the circulating current path of energy module 20 is open. When energy module 20 is connected in parallel with other energy modules and the voltage of the other energy modules is lower than that of energy module 20, energy module 20 can discharge to the other energy modules through this circulating current path and charging ports C+ and P- (C-). The current direction is: positive electrode of energy module 20 → diode D3 → discharge switch DSG2 → C+ → positive electrode of other energy modules → negative electrode of other energy modules → P- (C-) → negative electrode of energy module 20.

[0102] 5 c , when the charging switch CHG2 and the discharging switch DSG2 are both closed, the charging path and the circulating path are both conductive, and current can flow in two directions.

[0103] When the discharge switch DSG2 and the charge switch CHG2 are both turned off, the charging path and the circulating current path are both disconnected, and no current flows in the circuit.

[0104] Figures 6a and 6b illustrate the switch structure of the charge and discharge control section when two battery packs share a common negative electrode, using two battery packs as an example. Figures 6c and 6d illustrate the switch structure of the charge and discharge control section when two battery packs share a common positive electrode, using two battery packs as an example. For ease of description, the following embodiments are all based on the example of a battery pack sharing a common negative electrode.

[0105] In some embodiments, referring to Figures 6b and 6d , the BMS 10 may further include pre-discharge switches (PDSG1, PDSG2) and current-limiting resistors (R1, R2), with the pre-discharge switches connected in series with the current-limiting resistors. In a specific embodiment, the pre-discharge switches may be field-effect transistors, each including a body diode (D9, D10). In other embodiments, the pre-discharge switches may be connected in parallel with the diodes (D9, D10).

[0106] The current-limiting resistor limits the discharge current. When the battery pack is ready to discharge, directly closing the discharge switch in the discharge circuit will result in a large discharge current, which can damage both the discharge and charging switches. Therefore, when the battery pack is ready to discharge, the BMS10 can control the pre-discharge switch to close first, while keeping the discharge switch open. This allows the discharge current to flow through the current-limiting resistor, reducing the risk of damage to the discharge and charging switches. After a period of discharge, the discharge switch is closed again, and the pre-discharge switch is opened.

[0107] Those skilled in the art will appreciate that the above is merely an example of the structure of the charge and discharge control portion of the BMS. In other embodiments, the charge and discharge control portion may also adopt other switch structures, for example, the charging circuit includes only one switch, and / or the discharging circuit includes only one switch.

[0108] In other embodiments, more than one charging switch and / or more than one discharging switch may be provided on the charging circuit. More than one charging switch and / or more than one discharging switch may also be provided on the discharging circuit.

[0109] The charging switch and / or the discharging switch may be a transistor, a field effect transistor, a signal relay, an insulated gate bipolar transistor (IGBT), or other controllable switches capable of controlling the on / off of a circuit.

[0110] The BMS 10 may further include a switch driving circuit and at least one controller for controlling the closing and opening operations of the above-mentioned switches to perform the steps in any method embodiment of the present application.

[0111] FIG7 schematically shows the hardware structure of the controller. As shown in FIG7 , the controller includes a processor 11 and a memory 12 .

[0112] Memory 12 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs and non-volatile computer-executable program instructions. Memory 12 can include a program storage area and a data storage area. The program storage area can store an operating system and application programs required for at least one function; the data storage area can store data generated based on the use of BMS 10.

[0113] In addition, the memory 12 may include a high-speed random access memory and a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 12 may optionally include a memory remotely located relative to the processor 11, and such remote memory may be connected to the BMS 10 via a network.

[0114] Examples of the aforementioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0115] The processor 11 uses various interfaces and lines to connect various parts of the entire BMS 10, and performs various functions of the BMS 10 and processes data by running or executing software programs stored in the memory 12 and calling data stored in the memory 12, such as implementing the method described in any embodiment of the present application.

[0116] The processor 11 may include a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) device, etc. The processor 11 may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core, or any other such configuration.

[0117] Those skilled in the art will appreciate that FIG7 uses one processor 11 and one memory 12 as an example. In cases where the BMS 10 includes a multi-level management unit, or where multiple processors are required to work together, the BMS 10 may also include multiple processors, and the multiple processors may work together to implement the method described in any embodiment of the present application. Similarly, the memory may be one or more, and the processor 11 and memory 12 may be connected via a bus or other means. In the embodiment shown in FIG7 , the processor 11 and memory 12 are connected via a bus.

[0118] An embodiment of the present application also provides a battery pack parallel connection method, which can be applied to the BMS in any of the above embodiments, wherein "battery pack parallel connection" and "battery pack parallel operation" can mean that the battery pack is integrated into the electrical equipment.

[0119] Referring to FIG8 , the battery pack parallel connection method includes:

[0120] 101: In response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a charging state, controlling the switch on the discharge circuit to be in an off state, and the first battery pack performs parallel charging.

[0121] and / or,

[0122] 102: In response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a discharging state, controlling the switch on the charging circuit to be in an off state, so that the first battery pack performs a discharging parallel connection.

[0123] When battery packs are connected in parallel, if there are differences between the packs, such as voltage or SOC differences, current can flow from one pack to another through the connecting lines, creating a circulating current. Excessive circulating current can cause excessive current in one pack, potentially causing an overcurrent fault or even damaging the pack.

[0124] In this embodiment of the present application, when charging a battery pack, by controlling the switch on the discharge circuit to be in the off state, the discharge circuit is disconnected, thereby isolating the battery pack from the "discharge parallel connection" with other battery packs and reducing the circulating current generated between the battery packs through the discharge circuit during charging. When discharging a battery pack, by controlling the switch on the charging circuit to be in the off state, thereby isolating the battery pack from the "charge parallel connection" with other battery packs and reducing the circulating current generated through the charging circuit during discharge.

[0125] Moreover, when the electrical device switches from a discharge state to a charge state, some embodiments of the present application can directly control the switch on the discharge circuit to be in an off state, executing a charge-in-parallel connection. When the electrical device switches from a charge state to a discharge state, some embodiments of the present application can directly control the switch on the charge circuit to be in an off state, executing a discharge-in-parallel connection. This allows for convenient switching of the battery pack's operating state without having to shut down and restart, or after each battery pack has been disconnected from parallel connection and then reconnected, making the process much simpler.

[0126] Taking the first battery pack as an example, the following describes how to control the switch on the discharge circuit to be in the off state during charging. This is to disconnect the "parallel discharge" connection formed between the first battery pack and the other battery packs via the discharge circuit. Therefore, controlling the switch on the discharge circuit to be in the off state can mean controlling the switch on the discharge circuit of the first battery pack to be in the off state.

[0127] For the first battery pack, the BMS of the first battery pack disconnects its discharge circuit. For other battery packs, when they meet the first parallel connection condition and are in the charging state, the BMSs of the other battery packs can also disconnect their discharge circuits. This ensures that the discharge circuits of all battery packs in parallel charging are disconnected, cutting off the "discharge parallel connection" between the battery packs and reducing the circulating current generated in the discharge circuit.

[0128] Please refer to Figure 9. When the discharge circuits of battery pack BT1 and battery pack BT2 are in a disconnected state, the "discharge parallel" of battery pack BT1 and battery pack BT2 is disconnected, and battery pack BT1 cannot receive the circulating current of battery pack BT2 through the discharge circuit, or output the circulating current to battery pack BT2 through the discharge circuit.

[0129] In other embodiments, when the first battery pack is charging, the switch on the discharge circuit is controlled to be in the off state. Alternatively, the switches on the discharge circuits of each parallel-connected battery pack may be controlled to be in the off state. When the discharge circuits of each parallel-connected battery pack are in the off state, the "discharge parallel connection" formed by the discharge circuits of the first battery pack and the parallel-connected battery packs is disconnected, thereby reducing the circulating current generated by the discharge circuits. The "parallel-connected battery pack" here can refer to a battery pack whose discharge circuit switches are closed and connected to an electrical device.

[0130] As a specific implementation manner, when the first battery pack is charging, a control instruction may be transmitted to the BMS of each parallel-connected battery pack, instructing the BMS of each parallel-connected battery pack to control the switch on its discharge circuit to be in an off state.

[0131] Please refer to the embodiment shown in Figure 9. When the discharge circuit of the battery pack BT2 is in a disconnected state, the "discharge parallel" of the battery pack BT1 and the battery pack BT2 is disconnected, and the battery pack BT1 cannot receive the circulating current of the battery pack BT2 through the discharge circuit, or output the circulating current to the battery pack BT2 through the discharge circuit.

[0132] Of course, when the first battery pack is charging, the switch on the discharge circuit is controlled to be in the off state, or the switches on the discharge circuits of the first battery pack and each of the parallel-connected battery packs are controlled to be in the off state. Alternatively, when each battery pack in the electrical device determines that it is in the charging state, the switch on its own discharge circuit is controlled to be in the off state, thereby achieving the effect of having the switches on the discharge circuits of each battery pack in the electrical device be in the off state.

[0133] When the first battery pack is discharging, the switch on the charging circuit is controlled to be in the off state. This is to disconnect the "parallel charging" formed by the first battery pack and other battery packs through the charging circuit. Therefore, controlling the switch on the charging circuit to be in the off state may mean controlling the switch on the charging circuit of the first battery pack to be in the off state.

[0134] For the first battery pack, the BMS of the first battery pack disconnects its charging circuit. For other battery packs, when they meet the first parallel connection condition and are in the discharge state, the BMSs of the other battery packs can also disconnect their charging circuits. This allows the charging circuits of all the battery packs in the discharge-parallel connection to be disconnected, cutting off the "charging parallel connection" between the battery packs and reducing the circulating current generated in the charging circuit.

[0135] Please refer to Figure 9. When the charging circuits of battery pack BT1 and battery pack BT2 are in a disconnected state, the "charging in parallel" of battery pack BT1 and battery pack BT2 is disconnected, and battery pack BT1 cannot receive the circulating current of battery pack BT2 through the charging circuit, or output the circulating current to battery pack BT2 through the charging circuit.

[0136] Furthermore, when the charging circuit is disconnected, the connection between the battery pack and the charging port is disconnected, making the charging port uncharged. This improves the safety of the charging port and reduces the risk of electric shock caused by contact with the charging port.

[0137] In other embodiments, when the first battery pack is discharging, the switch on the charging circuit is controlled to be in the off state. Alternatively, the switches on the charging circuits of each parallel-connected battery pack may be controlled to be in the off state. When the charging circuits of each parallel-connected battery pack are in the off state, the "parallel charging" formed by the charging circuits of the first battery pack and the parallel-connected battery packs is disconnected, thereby reducing the circulating current generated in the charging circuits.

[0138] Furthermore, disconnecting the parallel-connected battery pack from the charging port reduces the voltage at the charging port, improving port safety and reducing the risk of electric shock. The "parallel-connected battery pack" here refers to a battery pack whose charging circuit switch is closed and connected to an electrical device.

[0139] As a specific implementation manner, when the first battery pack is discharging, a control instruction may be transmitted to the BMS of each parallel-connected battery pack, instructing the BMS of each parallel-connected battery pack to control the switch on its charging circuit to be in an off state.

[0140] Please refer to Figure 9. When the charging circuit of the battery pack BT2 is in the disconnected state, the "charging in parallel" of the battery pack BT1 and the battery pack BT2 is disconnected, and the battery pack BT1 cannot receive the circulating current of the battery pack BT2 through the charging circuit, or output the circulating current to the battery pack BT2 through the charging circuit.

[0141] Of course, when the first battery pack is discharging, the switch on the charging circuit is controlled to be in the off state. It is also possible to control the switches on the charging circuits of the first battery pack and each parallel battery pack to be in the off state. Alternatively, when each battery pack in the electrical equipment determines that it is in the discharging state, the switch on its own charging circuit is controlled to be in the off state, so as to achieve the effect that the switches on the charging circuits of each battery pack in the electrical equipment are all in the off state.

[0142] It will be appreciated that controlling the switch in the battery pack discharge circuit to be in the off state may involve controlling each switch in the battery pack discharge circuit to be in the off state. For example, where the discharge circuit includes a single switch, that switch is controlled to be in the off state. In the embodiment shown in FIG3 , both the charge switch CHG1 and the discharge switch DSG1 are controlled to be in the off state.

[0143] Controlling the switches in the battery pack charging circuit to be in the off state may involve controlling each switch in the battery pack charging circuit to be in the off state. For example, where the charging circuit includes a single switch, the switch is controlled to be in the off state. In the embodiment shown in FIG3 , the charging switch CHG2 and the discharging switch DSG2 are controlled to be in the off state.

[0144] In some embodiments, to improve safety when a battery pack is integrated into an electrical device, the battery pack's operating data is checked to see if it meets the first parallel connection condition. The battery pack is only integrated when it meets the first parallel connection condition. The operating data includes at least one of voltage data, current data, SOC data, temperature data, and communication status.

[0145] Specifically, in some embodiments, the first parallel connection condition includes at least one of the following:

[0146] (1) A voltage difference between the voltage of the first battery pack and the first voltage is within a first voltage difference range.

[0147] When the voltage difference between the battery packs is large, the circulating current between the battery packs is correspondingly large. When the voltage difference between the battery packs is small, the circulating current between the battery packs is correspondingly small. Maintaining the voltage difference between the first battery pack voltage and the first voltage within a certain voltage difference range can further reduce the circulating current between the battery packs.

[0148] The first voltage may be the average voltage of the battery packs, or the maximum voltage or minimum voltage of the battery packs. In some embodiments, when the first battery pack is in a charging state, the first voltage is the minimum voltage of the battery packs, and when the first battery pack is in a discharging state, the first voltage is the maximum voltage of the battery packs.

[0149] The value of the first voltage distinguishes the charge and discharge states. In the charge state, the first voltage is the minimum voltage, and in the discharge state, the first voltage is the maximum voltage, which can further reduce the circulation current between the battery packs.

[0150] If the battery packs are charging and operating in parallel, and the voltage difference between the battery pack with the lowest voltage is small, the charging and discharging currents between the battery packs can be effectively limited, thereby limiting the circulating current between the battery packs. If the battery packs are discharging and operating in parallel, and the voltage difference between the battery pack with the highest voltage is small, the charging and discharging currents between the battery packs can be effectively limited, thereby limiting the circulating current between the battery packs. The charging and discharging currents between battery packs refer to the fact that when two battery packs are connected in parallel, the battery pack with the higher voltage will discharge to the battery pack with the lower voltage, thereby forming a discharge current, and the battery pack with the lower voltage will be charged by the battery pack with the higher voltage, thereby forming a charging current.

[0151] The battery packs may be all the battery packs in the electrical device, or may be battery packs connected in parallel.

[0152] (2) The difference between the SOC of the first battery pack and the first SOC is within the first SOC range.

[0153] When the SOC differences between battery packs are large, the circulating currents between them are correspondingly large. When the SOC differences between battery packs are small, the circulating currents between them are correspondingly small. Maintaining the SOC difference between the first battery pack and the second SOC within a certain SOC range can further reduce the circulating currents between the battery packs.

[0154] The first SOC may be the average SOC of the battery packs, or the maximum SOC or minimum SOC of the battery packs. In some embodiments, when the first battery pack is in a charging state, the first SOC is the minimum SOC of the battery packs, and when the first battery pack is in a discharging state, the first SOC is the maximum SOC of the battery packs.

[0155] The value of the first SOC distinguishes the charge and discharge states. In the charge state, the first SOC is the minimum SOC, and in the discharge state, the first SOC is the maximum SOC, which can further reduce the circulation between the battery packs.

[0156] If the battery packs are charging and operating in parallel, and the SOC difference between the battery pack and the battery pack with the smallest SOC value is small, the charging and discharging currents between the battery packs can be effectively limited, thereby limiting the circulating currents between the battery packs. If the battery packs are discharging and operating in parallel, and the SOC difference between the battery pack and the battery pack with the largest SOC value is small, the charging and discharging currents between the battery packs can be effectively limited, thereby limiting the circulating currents between the battery packs.

[0157] The battery packs may be all the battery packs in the electrical device, or may be battery packs connected in parallel.

[0158] (3) The temperature of the first battery pack is within the first temperature range.

[0159] Limiting the temperature of the first battery pack to within a first temperature range can reduce damage to other battery packs caused by excessively high or low temperatures, or reduce the risk of thermal runaway caused by parallel operation.

[0160] (4) The first charging current rate is within a first current rate range, or the first discharging current rate is within a second current rate range. The first charging current rate is the maximum charging current rate of the battery packs connected in parallel, and the first discharging current rate is the maximum discharging current rate of the battery packs connected in parallel.

[0161] When the first battery pack is connected to an electrical device, if the existing parallel battery packs are experiencing high charging or discharging currents, a large circulating current may flow into the first battery pack, damaging the switching components within the first battery pack. Furthermore, the high charging or discharging currents may cause the voltage and power levels of the battery pack to be affected by the load, leading to inaccurate measurements. Parallel operation also carries certain risks.

[0162] To improve the safety of integrating the first battery pack, during discharge, the maximum discharge current rate of each battery pack connected in parallel is obtained. If the maximum discharge current rate exceeds the second current rate range, the first battery pack is not integrated. During charging, the maximum charge current rate of each battery pack connected in parallel is obtained. If the maximum charge current rate exceeds the first current rate range, the first battery pack is not integrated.

[0163] In other embodiments, whether to perform the parallel connection operation on the first battery pack can also be determined based on the charging current value or the discharging current value. That is, the first parallel connection condition includes the first charging current being within a first current range, or the first discharging current being within a second current range. The first charging current is the maximum charging current of the parallel battery packs, and the first discharging current is the maximum discharging current of the parallel battery packs.

[0164] The first battery pack can obtain the charging current rate or discharging current rate, charging current value or discharging current value of other battery packs by communication, for example, through a communication bus.

[0165] (5) Communication status of the first battery pack.

[0166] The communication status of the first battery pack indicates successful communication between the first battery pack and at least one of the other battery packs. Specifically, when the first battery pack receives a message from any other battery pack, it can be considered that the first battery pack has successfully communicated with the other battery pack, and the parallel connection operation (including determining whether the first parallel connection condition is met) can be performed.

[0167] In some embodiments, when the first battery pack does not receive a message from any battery pack, the first battery pack does not determine whether the first battery pack meets the first parallel condition, but is directly integrated into the power-consuming device and operates as a single pack.

[0168] It is understood that the first parallel connection condition may include one of the above conditions, or at least two of the above conditions at the same time. When the first parallel connection condition includes at least two of the above conditions, the first battery pack must meet at least two conditions at the same time before the first battery pack can perform the parallel connection operation.

[0169] The first pressure difference range, the first SOC range, the first temperature range, the first current rate range, and the second current rate range can be set according to specific application conditions, for example, according to the applicability of the battery pack, including: the characteristics of the battery cells in the battery pack (including the maximum allowable charge and discharge rate and / or time of the battery cells), the overcurrent capacity of the connector or connecting harness, the voltage resistance and overcurrent capacity of the electrical equipment, the performance of the components in the battery pack (such as switches), and other settings.

[0170] In some embodiments, the first pressure difference range can be set according to the internal resistance of the battery pack and the ability to withstand the maximum circulation current. The pressure difference range can be roughly the product of the tolerable circulation current size and the internal resistance of the battery pack. For example, the first pressure difference range can be [-1V, 1V], [-0.5V, 0.5V], etc. The first pressure difference range is not a limitation to this application.

[0171] The SOC difference between the battery packs can affect the circulation time between the battery packs. The greater the SOC difference between the two battery packs, the longer the circulation time will be after the two battery packs are connected in parallel. Therefore, the SOC range can be set according to the circulation time that the battery pack can withstand. In a specific implementation, the first SOC range can be set to [-5%, 5%].

[0172] In a specific implementation, the first temperature range may be set to [-10, 50° C.], the first current magnification range may be set to 0.2-0.3° C., and the second current magnification range may be set to 2-3° C.

[0173] Among them, when the electric device is connected to the charger, it can be considered that the electric device and the battery pack are in a charging state. When the electric device is not connected to the charger, it can be considered that the electric device and the battery pack are in a discharging state. Discharging can include discharging electronic components in the BMS (for example, powering the MCU on the BMS circuit board) and discharging the load of the electric device (for example, discharging loads such as the motor of an electric vehicle). The discharge state of the battery pack includes standby state and working state.

[0174] The battery pack can confirm that it is in a charging state through a charging signal. In one implementation, when the charger is connected to the charging port, the charger sends a charging signal to the battery pack through data communication. After the battery pack receives the charging signal, it can confirm that the battery pack is in a charging state.

[0175] In another implementation, a hardware detection circuit may be provided on the BMS to detect whether a charger is plugged into the charging port. Before and after the charger is plugged in, the hardware detection circuit outputs different level signals. After the controller on the BMS detects the flip of the level signal, it can be determined that the charger has been plugged into the charging port and the electrical device and battery pack are in a charging state.

[0176] If no charging signal is received, for example, if no charging signal is received within a preset time, it can be considered that the electrical device and the battery pack are in a discharging state.

[0177] In some embodiments, in order to ensure that the battery packs that meet the parallel connection conditions are connected in parallel approximately synchronously, a parallel connection request instruction is also sent when the battery pack is connected to the electrical equipment.

[0178] FIG10 shows an embodiment of a method for connecting battery packs in parallel during charging, the method comprising:

[0179] 101a: In response to the first battery pack meeting the first parallel connection condition, the first battery pack sends a parallel connection request instruction.

[0180] 101b: In response to the first battery pack being in a charging state, opening the switch on the discharge circuit of the first battery pack and closing the charging switch on the charging circuit of the first battery pack.

[0181] As a specific implementation, the first battery pack executes parallel connection determination logic (including determining whether the battery pack meets a first parallel connection condition). When the first battery pack meets the first parallel connection condition, the first battery pack sends a parallel connection request instruction. When the first battery pack is in a charging state, the switch on the first battery pack's discharge circuit is opened, thereby disconnecting the discharge circuit. The charging switch on the first battery pack's charging circuit is closed, thereby connecting the charging path of the charging circuit, allowing the first battery pack to charge through this charging path.

[0182] It is understandable that when the electrical equipment is just turned on, the switches on the charging circuit and the discharging circuit of the first battery pack are in the disconnected state. At this time, the microcontroller of the BMS10 of the first battery pack does not need to send an instruction to disconnect the switch on the discharge circuit. In this scenario, 101b may also include: in response to the first battery pack being in the charging state, closing the charging switch on the charging circuit of the first battery pack.

[0183] Taking the embodiment shown in FIG9 as an example, in response to the first battery pack BT1 meeting the first parallel connection condition, the first battery pack BT1 sends a parallel connection request instruction. In response to the first battery pack BT1 being in a charging state, the charging switch CHG1 and the discharging switch DSG1 are opened, and the charging switch CHG2 is closed.

[0184] FIG11 shows an embodiment of a method for connecting battery packs in parallel during discharge, the method comprising:

[0185] 102a: In response to the first battery pack meeting the first parallel connection condition, the first battery pack sends a parallel connection request instruction.

[0186] 102b: In response to the first battery pack being in a discharging state, disconnect the switch on the charging circuit of the first battery pack and close the discharge switch on the discharging circuit of the first battery pack.

[0187] As a specific implementation, the first battery pack executes parallel connection determination logic. When the first battery pack meets the first parallel connection condition, the first battery pack sends a parallel connection request instruction. When the first battery pack is in a discharging state, the switch on the first battery pack's charging circuit is opened, disconnecting the charging circuit. The discharge switch on the first battery pack's discharging circuit is closed, connecting the discharge path of the discharge circuit, allowing the first battery pack to discharge through this discharge path.

[0188] It is understandable that when the electrical equipment is just turned on, the switches on the charging circuit and the discharging circuit of the first battery pack are both in the disconnected state. At this time, the microcontroller of the BMS10 of the first battery pack does not need to send an instruction to disconnect the switch on the charging circuit. In this scenario, 102b may also include: in response to the first battery pack being in the discharging state, closing the discharge switch on the discharge circuit of the first battery pack.

[0189] Taking the embodiment shown in FIG9 as an example, in response to the first battery pack meeting the first parallel connection condition, the first battery pack sends a parallel connection request instruction. In response to the first battery pack being in a discharging state, the charging switch CHG2 and the discharging switch DSG2 are opened, and the discharging switch DSG1 is closed.

[0190] The parallel connection request instruction can be used to notify other battery packs to be connected to the power-consuming device. When the other battery packs also meet the first parallel connection condition, the other battery packs are also connected to the power-consuming device, so that the first battery pack and the other battery packs are roughly synchronized in parallel.

[0191] In some embodiments, the battery pack in an electrical device can periodically execute the parallel connection determination logic at regular intervals (e.g., 1s, 2s, etc.). The battery pack also executes the parallel connection determination logic after receiving a parallel connection request instruction from another battery pack. Because the parallel connection request instruction triggers the battery pack to execute the parallel connection determination logic, the battery pack can periodically execute the parallel connection determination logic at longer intervals, reducing the amount of computation required by the battery pack.

[0192] On the other hand, the parallel connection request command can also carry information indicating the charge and discharge status of the electrical device. A battery pack may misjudge the charge and discharge status. For example, battery pack A remains in the discharge state because it hasn't received the charging signal from the charger. If battery pack A can receive the parallel connection request command sent by other battery packs, it can correct its operating state and change it to the charging state. In other words, the parallel connection request command can reduce the possibility of battery packs misjudging their operating status.

[0193] The following describes the parallel charging and parallel discharging methods for battery packs, that is, the control of the charging circuit when the battery pack is charged, and the control of the discharging circuit when the battery pack is discharged.

[0194] In some embodiments, charging the first battery pack in parallel includes closing a charging switch on the first battery pack's charging circuit. Alternatively, the method includes closing both the charging switch and the discharging switch on the first battery pack's charging circuit. If other battery packs are already connected in parallel, the other battery packs may transmit circulating current to the first battery pack through their circulating current paths.

[0195] 9 , when the battery pack BT1 is not connected in parallel and the battery pack BT2 is connected in parallel, if the voltage of BT2 is higher than that of BT1, a circulating current may be transmitted to BT1 through the circulating current path.

[0196] In other embodiments, to reduce circulating current, the battery packs performing parallel charging also include operating the circulating current path. For example, in the embodiment shown in FIG9 , the power-consuming device is in a charging state, battery pack BT1 is not incorporated (battery pack BT1 can represent a battery pack that is not charged in parallel), and battery pack BT2 is incorporated (battery pack BT2 can represent one or more charged battery packs that are in parallel). Please refer to FIG12a for the status of battery packs BT1 and BT2.

[0197] The battery pack BT1 performs parallel charging, which can include the following four stages:

[0198] Phase 1: Disconnect the circulation path of BT2.

[0199] The conduction and disconnection of the circulation path in the charging circuit can be controlled by the discharge switch. Disconnecting the circulation path can be by disconnecting the discharge switch in the charging circuit. Taking the embodiment shown in Figure 9 as an example, disconnecting the circulation path of BT2 includes disconnecting the discharge switch DSG4 of BT2. Before closing the switch on the charging circuit of the battery pack BT1, the battery pack BT2 can be cut off from transmitting the circulation current to the battery pack BT1 through the circulation path. Please refer to Figure 12b.

[0200] As a specific implementation manner, the battery pack BT2 disconnects the discharge switch on the charging circuit of the battery pack BT2 in response to receiving the parallel request instruction (in this embodiment, receiving the parallel request instruction sent by BT1).

[0201] In this embodiment, BT2 is in a charged parallel state. In order to reduce the circulation between the first battery pack BT1 and the second battery pack BT2, the circulation path of BT2 is first disconnected, and then the charging path of BT1 is closed. In other embodiments, when the electrical equipment is just turned on, the charging circuit and the discharging circuit of each battery pack are in a disconnected state, and the circulation path of each battery pack is in a disconnected state. This stage 1 can be omitted, and stage 2 can be directly skipped. In some other embodiments of the present application, the circulation path of the second battery pack BT2 can be disconnected by executing the operation of stage 1.

[0202] Phase 2: Turn on the charging path of BT1.

[0203] The charging path within the charging circuit can be turned on and off by a charging switch. Turning on the charging path can be controlling the charging switch within the closed charging circuit. For example, in the embodiment shown in FIG9 , turning on the charging path for BT1 includes closing BT1's charging switch CHG2. Battery pack BT1 can be charged via the charging path, as shown in FIG12c .

[0204] In some embodiments, to confirm that the circulation path of the parallel battery packs is disconnected and reduce the circulating current, battery pack BT1 closes the charging switch on the charging circuit in response to receiving the first information. The first information is used to indicate that the circulation path of battery pack BT2 is disconnected. In this embodiment of the present application, it can be that the discharge switch on the charging circuit of battery pack BT2 is in the open state.

[0205] Phase 3: Turn on the circulation path of BT1 and BT2.

[0206] The conductive loop path can be achieved by closing the discharge switch in the charging circuit. Taking the embodiment shown in Figure 9 as an example, the conductive loop path of BT1 includes closing the discharge switch DSG2, and the conductive loop path of BT2 includes closing the discharge switch DSG4 of BT2. Please refer to Figure 12d.

[0207] To limit circulating current, in some embodiments, stage 3 further includes: closing a discharge switch on the charging circuit of battery pack BT1 in response to operating data of battery pack BT1 satisfying a first condition, and / or closing a discharge switch on the charging circuit of battery pack BT2 in response to operating data of battery pack BT2 satisfying a first condition. The first condition represents a condition for limiting circulating current and may include at least one of the following conditions:

[0208] (1) The charging current of the battery pack is greater than or equal to the first current threshold.

[0209] (2) The charging current of the battery pack is less than the first current threshold, and the voltage difference between the voltage of the battery pack and the second voltage is within the second voltage difference range.

[0210] Taking battery pack BT1 as an example, according to I = V / R, if the internal resistance remains constant, the greater the current I, the greater the voltage V. When the battery pack BT1 is charging, assuming the internal resistance of the battery pack is roughly constant, the greater the charging current, the greater the voltage difference between the battery pack BT1 and the charger, and the lower the battery pack voltage.

[0211] If the charging current of the battery pack BT1 is greater than or equal to the first current threshold, the voltage difference between the battery pack and the charger is large, the voltage of the battery pack is small, and the battery pack with a small voltage needs to be charged first. Because charging the battery pack with a small voltage first can reduce the voltage difference between the battery packs, it can be considered that the battery pack BT1 meets the circulation limit conditions.

[0212] If the charging current of battery pack BT1 is less than the first current threshold, the voltage difference between the battery pack and the charger is small, the battery pack voltage is large, and the battery pack voltage is closer to the charger. Battery pack BT1 may discharge to other battery packs (i.e., a circulating current occurs). In this case, further combined with other operating data can be used to determine whether battery pack BT1 has a circulating current risk.

[0213] Therefore, when the charging current of the battery pack BT1 is greater than or equal to the first current threshold, it can be considered that the first battery pack meets the circulation restriction condition, its circulation path can be opened, and the discharge switch on the charging circuit of the battery pack BT1 can be closed.

[0214] When the charging current of the battery pack BT1 is less than the first current threshold, it can be further determined whether the voltage difference between the battery pack BT1 and the second voltage is within the second voltage difference range. If the voltage difference is within the second voltage difference range, the voltage difference between the battery packs is small, and the risk of large circulation is small. The circulation path can be turned on and the discharge switch on the charging circuit of the battery pack BT1 can be closed.

[0215] Among them, those skilled in the art can understand that "large circulation" means that the circulation value between the battery pack BT1 and other battery packs is larger, and conversely, "small circulation" means that the circulation value between the battery pack BT1 and other battery packs is smaller.

[0216] If the charging current of the battery pack BT1 is less than the first current threshold, and the voltage difference between the BT1 voltage and the second voltage exceeds the second voltage difference range, the discharge switch on the charging circuit is not closed. In some embodiments, the determination may be repeated after a period of time.

[0217] The second voltage may be an average voltage of each battery pack, or a maximum voltage or a minimum voltage of each battery pack. In some embodiments, the second voltage is the minimum voltage of each battery pack.

[0218] The second pressure differential range can be set based on specific application conditions, such as the applicability of the battery pack, the performance of components (e.g., switches) in the battery pack, etc. The second pressure differential range can be the same as or different from the first pressure differential range. In some embodiments, the second pressure differential range is within the first pressure differential range and is smaller than the first pressure differential range.

[0219] The first current threshold can be set based on specific application scenarios, for example, based on the maximum allowable charging current and / or time of the battery cells in the battery pack, the model and specifications of the charger, the overcurrent capacity of the connector or connecting harness, the withstand voltage and overcurrent capacity of the electrical equipment, and the performance of components in the battery pack (such as switches). In one specific implementation of the present application, the first current threshold can be 2A.

[0220] Phase 4: If there is a risk of circulating current, disconnect the charging circuit of BT1 or just disconnect the circulating current path. If there is no risk of circulating current, complete the charging and parallel operation.

[0221] To further reduce circulating current, after the charging and discharging switches on the battery pack BT1 charging circuit are closed, a further step of determining the risk of circulating current is included. If a circulating current risk exists, the discharging and charging switches on the battery pack BT1 charging circuit are disconnected, or only the discharging switch on the battery pack BT1 charging circuit can be disconnected. If no circulating current risk exists, the circulating current path of the battery pack BT1 is kept open. In other embodiments, the battery packs may be charged in parallel without including stage 4.

[0222] Whether there is a circulating current risk between battery packs can be determined by determining whether the battery pack meets a first circulating current condition, wherein the first circulating current condition includes that the absolute value of the difference between the current magnification of the first battery pack and the first current magnification is greater than or equal to a first current magnification threshold.

[0223] The first current rate is the maximum charging current rate among the battery packs connected in parallel. As a specific implementation method, the charging current of each battery pack connected in parallel can be obtained, and then the maximum charging current rate can be selected as the first current rate.

[0224] When the current directions of two battery packs are opposite, for example, the current of one battery pack is positive and the current of the other battery pack is negative, it can be considered that one battery pack is charging and the other battery pack is discharging, and the risk of circulating current between the battery packs is relatively high. When the currents of the two battery packs are both positive or both negative, but the values ​​differ significantly, the risk of circulating current between the battery packs is also relatively high. The embodiment of the present application uses the maximum charging current rate (i.e., the first current rate) of each battery pack connected in parallel as a benchmark, and uses the absolute value of the difference between the current rate of the first battery pack and the first current rate as the judgment condition, which can effectively identify the risk of circulating current.

[0225] For example, the discharge current can be set as negative and the charge current as positive. When the current of the battery pack BT1 is the discharge current, the current magnification of the battery pack BT1 is negative, the first current magnification is positive, and the absolute value of the difference between the two is large. When the current of the battery pack BT1 is the charge current, the current magnification of the battery pack BT1 and the first current magnification are both positive. If the current magnification of the battery pack BT1 differs significantly from the first current magnification, the absolute value of the difference between the two is also large. In some other embodiments, the discharge current can also be set as positive and the charge current can be set as negative.

[0226] In other embodiments, the presence of a circulating current risk can also be determined by the charging current value. The first circulating current condition can also include: the absolute value of the difference between the current of the first battery pack and the first current is greater than or equal to a first current threshold. The first current is the maximum charging current of all parallel battery packs.

[0227] The first current rate threshold can be set according to the specific application situation, for example, it can be determined based on the maximum charging current and / or time allowed for the battery cells in the battery pack, the model and specifications of the charger, the overcurrent capacity of the connector or connecting harness, the voltage resistance and overcurrent capacity of the electrical equipment, and the performance of the components in the battery pack (such as switches).

[0228] FIG13 shows a flow chart of a specific embodiment of parallel charging of battery packs.

[0229] In some embodiments, discharging the first battery pack in parallel includes closing a discharge switch on the first battery pack's discharge circuit. Alternatively, the method includes closing a charge switch and a discharge switch on the first battery pack's discharge circuit. If other battery packs are already connected in parallel, the first battery pack may transmit circulating current to the other battery packs through the circulating current paths of the other battery packs.

[0230] 9 , when the battery pack BT1 is not connected in parallel and the battery pack BT2 is connected in parallel, if the voltage of BT1 is higher than that of BT2, a circulating current may be transmitted to BT2 through the circulating current path.

[0231] In other embodiments, to reduce circulating current, the battery pack discharge parallel connection also includes operations on the circulating current path. For example, the embodiment shown in FIG9 illustrates that the electrical device is in a discharging state, battery pack BT1 is not connected (battery pack BT1 can represent a non-discharged parallel battery pack), and battery pack BT2 is connected (battery pack BT2 can represent one or more discharged parallel battery packs). Please refer to FIG14a for the status of battery packs BT1 and BT2.

[0232] The battery pack BT1 performs discharge parallel connection, which can include the following four stages:

[0233] Phase 1: Disconnect the circulation path of BT2.

[0234] The conduction and disconnection of the circulation path in the discharge circuit can be controlled by the charging switch. Disconnecting the circulation path can be done by disconnecting the charging switch in the discharge circuit. Taking the embodiment shown in Figure 9 as an example, disconnecting the circulation path of BT2 includes disconnecting the charging switch CHG3 of BT2, so that the battery pack BT1 cannot transmit the circulation current to the battery pack BT2 through the circulation path, which can further reduce the circulation current. Please refer to Figure 14b.

[0235] As a specific implementation manner, the battery pack BT2 disconnects the charging switch on the discharge circuit of the battery pack BT2 in response to receiving the parallel request instruction (in this embodiment, receiving the parallel request instruction sent by BT1).

[0236] In this embodiment, BT2 is in a discharged parallel state. In order to reduce the circulation between the first battery pack BT1 and the second battery pack BT2, the circulation path of BT2 is first disconnected, and then the discharge path of BT1 is turned on. In other embodiments, when the electrical equipment is just turned on, the switches on the charging circuit and the discharging circuit of each battery pack can be considered to be in the disconnected state, and the circulation path of each battery pack is in the disconnected state. In this case, stage 1 can be omitted, and stage 1 can be directly skipped to execute stage 2. In some other embodiments of the present application, the circulation path of the second battery pack BT2 can be disconnected by executing the operation of stage 1.

[0237] Phase 2: Turn on the discharge path of BT1.

[0238] The discharge path in the discharge circuit can be turned on and off by a discharge switch. Turning on the discharge path can be achieved by closing the discharge switch in the discharge circuit. For example, in the embodiment shown in Figure 9 , turning on the discharge path of BT1 includes closing BT1's discharge switch DSG1. Battery pack BT1 can be charged via the discharge path, as shown in Figure 14c.

[0239] In an embodiment including a pre-discharge switch, such as the embodiment shown in FIG6b and FIG6d, before closing the discharge switch, the pre-discharge switch may be closed first, and then the pre-discharge switch may be opened after a certain time interval, and then the discharge switch may be closed.

[0240] In some embodiments, to confirm that the circulation path of the parallel battery packs is disconnected and reduce the circulating current, battery pack BT1 closes the discharge switch on the discharge circuit in response to receiving the second information. The second information is used to indicate that the circulation path of battery pack BT2 is disconnected. In this embodiment of the present application, this may be the disconnection of the charging switch on the discharge circuit of battery pack BT2.

[0241] Phase 3: Turn on the circulation path of BT1 and BT2.

[0242] The conductive loop path can be achieved by closing the charging switch in the discharge loop. Taking the embodiment shown in Figure 9 as an example, the conductive loop path of BT1 includes closing the charging switch CHG1, and the conductive loop path of BT2 includes closing the charging switch CHG3 of BT2, please refer to Figure 14d.

[0243] To limit the circulating current, in some specific embodiments, stage 3 may further include: in response to the operating data of the battery pack BT1 satisfying a second condition, closing the charging switch on the discharge circuit of the battery pack BT1, and / or, in response to the operating data of the battery pack BT2 satisfying a second condition, closing the charging switch on the discharge circuit of the battery pack BT2. The second condition is used to indicate the condition for limiting the circulating current, and may include at least one of the following conditions:

[0244] (1) The discharge current of the battery pack is greater than or equal to the second current threshold.

[0245] (2) The discharge current of the battery pack is less than the second current threshold, and the voltage difference between the voltage of the battery pack and the third voltage is within the third voltage difference range.

[0246] Taking battery pack BT1 as an example, according to I = V / R, if the internal resistance remains constant, the greater the current I, the greater the voltage V. When the battery pack BT1 is in a discharging state, assuming the internal resistance of the battery pack is roughly constant, the greater the discharge current, the greater the voltage difference between the battery pack BT1 and the load, and the greater the battery pack voltage.

[0247] If the discharge current of the battery pack BT1 is greater than or equal to the second current threshold, the voltage difference between the battery pack and the load is large, and the voltage of the battery pack is large. The battery pack with a large voltage needs to be discharged first, because discharging the battery pack with a large voltage first can reduce the voltage difference between the battery packs. Therefore, it can be considered that the battery pack BT1 meets the circulation limit conditions.

[0248] If the discharge current of battery pack BT1 is less than the second current threshold, the voltage difference between the battery pack and the load is small, the battery pack voltage is small, and the battery pack voltage is closer to the load. Other battery packs may be discharging into battery pack BT1 (i.e., circulating current is occurring). In this case, further judgment can be made based on other electrical parameters.

[0249] Therefore, when the discharge current of the battery pack BT1 is greater than or equal to the second current threshold, it can be considered that the first battery pack meets the circulation restriction condition, its circulation path can be turned on, and the charging switch on the discharge loop can be closed.

[0250] When the discharge current of the battery pack BT1 is less than the second current threshold, it can be further determined whether the voltage difference between the battery pack BT1 and the third voltage is within the third voltage difference range. If the voltage difference is within the third voltage difference range, the voltage difference between the battery packs is small, and the risk of large circulation is small. The circulation path can be turned on and the charging switch on the discharge circuit of the battery pack BT1 can be closed.

[0251] Among them, those skilled in the art can understand that "large circulation" means that the circulation value between the battery pack BT1 and other battery packs is larger, and conversely, "small circulation" means that the circulation value between the battery pack BT1 and other battery packs is smaller.

[0252] If the discharge current of the battery pack BT1 is less than the second current threshold, and the voltage difference between the BT1 voltage and the third voltage exceeds the third voltage difference range, the charging switch on the discharge circuit is not closed. In some embodiments, the determination may be repeated after a period of time.

[0253] The third voltage may be an average voltage of each battery pack, or a maximum voltage or a minimum voltage of each battery pack. In some embodiments, the third voltage is the maximum voltage of each battery pack.

[0254] The third pressure differential range can be set based on specific application circumstances, for example, based on the maximum allowable charging current and / or time of the battery cells in the battery pack, the model and specifications of the charger, the current capacity of the connector or wiring harness, the voltage and current capacity of the electrical equipment, and the performance of components in the battery pack (e.g., switches). The third pressure differential range and the first pressure differential range can be the same or different. In some embodiments, the third pressure differential range is within the first pressure differential range and is smaller than the first pressure differential range.

[0255] The second current threshold can be set based on specific application scenarios, for example, based on the maximum allowable charging current and / or time of the battery cells in the battery pack, the model and specifications of the charger, the overcurrent capacity of the connector or connecting harness, the withstand voltage and overcurrent capacity of the electrical equipment, and the performance of components in the battery pack (such as switches). In one specific implementation of the present application, the second current threshold can be 2A.

[0256] Phase 4: If there is a risk of circulating current, disconnect the discharge circuit of BT1, or just disconnect the circulating current path. If there is no risk of circulating current, complete the charging and parallel operation.

[0257] To further reduce circulating current, after the charging and discharging switches on the discharge circuit of battery pack BT1 are closed, a step is included to determine the risk of circulating current. If a circulating current risk exists, the charging and discharging switches on the discharge circuit of battery pack BT1 are disconnected. Alternatively, only the charging switch may be disconnected. If no circulating current risk exists, the circulating current path of battery pack BT1 is kept open. In other embodiments, the battery pack discharge in parallel may also not include stage 4.

[0258] Whether there is a circulating current risk between battery packs can be determined by determining whether the battery packs meet a second circulating current condition, where the second circulating current condition includes the absolute value of the difference between the current magnification of the first battery pack and the second current magnification being greater than or equal to a second current magnification threshold.

[0259] The second current rate is the maximum discharge current rate among the battery packs connected in parallel. As a specific implementation, the discharge currents of the battery packs connected in parallel can be obtained, and then the maximum discharge current rate can be selected as the second current rate.

[0260] When the current directions of two battery packs are opposite, for example, the current of one battery pack is positive and the current of the other battery pack is negative, it can be considered that one battery pack is charging and the other battery pack is discharging, and the risk of circulation between the battery packs is relatively high. When the currents of the two battery packs are both positive or both negative, but the values ​​differ greatly, the risk of circulation between the battery packs is also relatively high. The embodiment of the present application uses the maximum discharge current rate (i.e., the second current rate) of each battery pack connected in parallel as a benchmark, and uses the absolute value of the difference between the current rate of the first battery pack and the second current rate as a judgment condition, which can well identify situations where there is a large circulation risk.

[0261] For example, the discharge current can be set as negative and the charge current as positive. When the current of battery pack BT1 is the charge current, the current magnification of battery pack BT1 is positive, the second current magnification is negative, and the absolute value of the difference between the two is large. When the current of battery pack BT1 is the discharge current, the current magnification of battery pack BT1 and the first current magnification are both negative. If the current magnification of battery pack BT1 differs significantly from the first current magnification, the absolute value of the difference between the two is also large.

[0262] In some other implementations, the discharge current may be positive and the charge current may be negative.

[0263] In other embodiments, the presence of a circulating current risk can also be determined by the discharge current value. The first circulating current condition can also include: the absolute value of the difference between the current of the first battery pack and the second current is greater than or equal to a second current threshold. The second current is the maximum discharge current of all parallel battery packs.

[0264] The second current threshold can be set according to specific application conditions, for example, according to the large circulating current tolerance of the battery pack.

[0265] FIG15 shows a flow chart of a specific embodiment of parallel charging of battery packs.

[0266] In some embodiments, the battery pack parallel connection method also includes detecting the on / off status of the charging switch and / or the discharging switch on the battery pack charging circuit and sending a third message, and / or detecting the on / off status of the charging switch and / or the discharging switch on the battery pack discharging circuit and sending a fourth message.

[0267] The third information is used to indicate the on / off status of the charging switch and / or the discharging switch on the charging circuit, and the fourth information is used to indicate the on / off status of the charging switch and / or the discharging switch on the discharging circuit. In some embodiments of the present application, the third information and the fourth information may be referred to as checkback information.

[0268] As a specific implementation, after the BMS sends a closing or opening signal to the charging or discharging switch, it detects the on / off status of the charging or discharging switch and transmits this status to other battery packs. By receiving the third or fourth information indicating the on / off status of the switch, the other battery packs can know the on / off status of the switch of the sending battery pack, clarify the specific stage of the battery pack in the parallel process, and provide a reference for the next stage of operation.

[0269] For example, taking the embodiment in which parallel charging includes four stages as an example, when the discharge switches on the charging circuits of battery pack BT1 and battery pack BT2 are in the disconnected state, the parallel process is in the first stage. Each battery pack can clearly identify the current stage as the first stage through the received feedback information and can enter the second stage (closing the charging switch on the BT1 charging circuit).

[0270] When the charging switches on the charging circuits of battery pack BT1 and battery pack BT2 are in the closed state and the discharging switches are in the open state, the parallel process is in the second stage. Each battery pack can determine that the current stage is the second stage through the received feedback information and can enter the third stage (closing the discharging switches on the BT1 and BT2 charging circuits).

[0271] When the charging switches on the charging circuits of battery pack BT1 and battery pack BT2 are in the closed state and the discharging switches are in the closed state, the parallel process is in the third stage. Each battery pack can confirm that the current stage is the third stage through the received feedback information and can enter the fourth stage.

[0272] In some embodiments of the present application, there is no step of detecting the on / off check information of the charging switch and / or the discharging switch during the parallel operation of the battery pack. Instead, a delay time is set for the on / off of the charging switch and / or the discharging switch. For example, after the BMS sends a control signal to open or close the charging switch and / or the discharging switch, it extends a period of time (for example, 1s) to ensure that the switch is normally closed or opened. It can be understood that in the embodiment of the present application where there is a detection of the on / off of the charging switch and / or the discharging switch, it is not necessary to set a delay time, which is beneficial to shortening the parallel operation time of the battery pack. In addition, when a problem is encountered in the parallel operation process, a reset method is often used to restart the parallel operation process. The use of the back-check switch and the sending of back-check information can ensure the status of each stage, thereby ensuring to a certain extent that the predetermined parallel operation process can be executed and the parallel operation can be completed.

[0273] FIG16 takes charging as an example and shows a flow chart of an embodiment of a battery pack parallel connection method including a backcheck step. The switch backcheck operation during discharge can be referred to FIG16 and will not be described in detail here.

[0274] An embodiment of the present application also provides a storage medium storing computer-executable instructions, which are executed by one or more processors, such as a processor 11 in Figure 7, so that the one or more processors can execute the battery pack parallel connection method in any of the above method embodiments, for example, executing method steps 101 and 102 in Figure 8 described above.

[0275] The present application also provides a computer program product, comprising a computer program stored on a non-volatile computer-readable storage medium, the computer program including program instructions that, when executed by a machine (e.g., a BMS), cause the machine to perform the above-described method for connecting battery packs in parallel. For example, steps 101 and 102 of the method described above in FIG. 8 are performed.

[0276] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0277] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Based on the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, and the steps may be implemented in any order. A person skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some of the technical features may be replaced by equivalents. However, such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery pack parallel connection method, characterized in that: In response to the first battery pack meeting the first parallel connection condition and being in a charging state, controlling the switch on the discharge circuit to be in an off state, so that the first battery pack performs parallel charging; or, In response to the first battery pack meeting the first parallel connection condition and being in a discharging state, controlling the switch on the charging circuit to be in an off state, so that the first battery pack performs discharging parallel connection; The first parallel condition includes that the operating data of the first battery pack meets the parallel condition, and the operating data includes at least one of voltage data, current data, SOC data, temperature data, and communication status.

2. The battery pack parallel connection method according to claim 1, characterized in that: The first parallel connection condition includes at least one of the following: A voltage difference between the voltage of the first battery pack and the first voltage is within a first voltage difference range; The difference between the SOC of the first battery pack and the first SOC is within a first SOC range; The temperature of the first battery pack is within a first temperature range; The first charging current rate is within a first current rate range, or the first discharging current rate is within a second current rate range; the communication status of the first battery pack; Among them, when the first battery pack is in a charging state, the first voltage is the minimum voltage among all battery packs, and the first SOC is the minimum SOC among all battery packs; when the first battery pack is in a discharging state, the first voltage is the maximum voltage among all battery packs, and the first SOC is the maximum SOC among all battery packs; the first charging current rate is the maximum charging current rate among the battery packs connected in parallel, and the first discharging current rate is the maximum discharging current rate among the battery packs connected in parallel. The communication status of the first battery pack is used to indicate that the first battery pack has successfully communicated with at least one of the battery packs.

3. The battery pack parallel connection method according to claim 1, characterized in that: The controlling the switch on the discharge circuit to be in an off state, and the first battery pack to perform parallel charging, includes: controlling the switches on the discharge circuits of the first battery pack and / or each parallel-connected battery pack to be in an off state, and the first battery pack to perform parallel charging; The control of the switch on the charging circuit being in an off state and the first battery pack performing discharge in parallel includes: controlling the switches on the charging circuits of the first battery pack and / or each parallel battery pack to be in an off state and the first battery pack performing discharge in parallel.

4. The battery pack parallel connection method according to any one of claims 1 to 3, characterized in that: In response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a charging state, controlling the switch on the discharge circuit to be in an off state, so that the first battery pack performs charging in parallel, includes: in response to the first battery pack meeting the first parallel connection condition, the first battery pack sending a parallel connection request instruction; In response to the first battery pack being in a charging state, opening a switch on a discharging circuit of the first battery pack and closing a charging switch on a charging circuit of the first battery pack; or, The switch on the discharging circuit of the first battery pack is in an open state. In response to the first battery pack being in a charging state, the charging switch on the charging circuit of the first battery pack is closed.

5. The battery pack parallel connection method according to claim 4, characterized in that: Closing the charging switch on the charging circuit of the first battery pack includes: closing the charging switch in response to receiving first information, wherein the first information is used to indicate that the discharge switch on the charging circuit of the second battery pack is in an open state, and the second battery pack is a battery pack connected in parallel.

6. The battery pack parallel connection method according to claim 4, characterized in that: In response to the second battery pack receiving the parallel connection request instruction, the discharge switch on the charging circuit of the second battery pack is disconnected, and the second battery pack is a parallel connected battery pack.

7. The battery pack parallel connection method according to any one of claim 4, characterized in that: In response to the first battery pack satisfying the first parallel connection condition and the first battery pack being in a charging state, controlling the switch on the discharge circuit of the first battery pack to be in an open state, so that the first battery pack performs parallel charging, further comprising: in response to the first battery pack satisfying the first condition, closing the discharge switch on the charging circuit of the first battery pack, and / or, in response to the second battery pack satisfying the first condition, closing the discharge switch on the charging circuit of the second battery pack, so that the second battery pack is the parallel connected battery pack; The first condition includes at least one of the following: The charging current of the battery pack is greater than or equal to the first current threshold; The charging current of the battery pack is less than the first current threshold, and the voltage difference between the voltage of the battery pack and the second voltage is within a second voltage difference range, and the second voltage is the minimum voltage of each battery pack.

8. The battery pack parallel connection method according to claim 7, characterized in that: The battery pack parallel connection method further includes: in response to the first battery pack meeting a first circulation condition, disconnecting a charging switch and a discharging switch on a charging circuit of the first battery pack; Among them, the first circulation condition includes that the absolute value of the difference between the current rate of the first battery pack and the first current rate is greater than or equal to the first current rate threshold; the first current rate is the maximum charging current rate among all the battery packs connected in parallel, and the current rate of the first battery pack includes a charging current rate or a discharging current rate, the charging current rate is a positive value, and the discharging current rate is a negative value.

9. The battery pack parallel connection method according to any one of claims 1 to 3, characterized in that: In response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a discharging state, controlling the switch on the charging circuit to be in an off state, so that the first battery pack performs discharge parallel connection, includes: in response to the first battery pack meeting the first parallel connection condition, the first battery pack sending a parallel connection request instruction; In response to the first battery pack being in a discharging state, opening a switch on a charging circuit of the first battery pack and closing a discharge switch on a discharging circuit of the first battery pack; or, The switch on the charging circuit of the first battery pack is in an open state. In response to the first battery pack being in a discharging state, the discharge switch on the discharging circuit of the first battery pack is closed.

10. The battery pack parallel connection method according to claim 9, characterized in that: Closing the discharge switch on the discharge loop of the first battery pack includes: closing the discharge switch in response to receiving second information, wherein the second information is used to indicate that the charging switch on the discharge loop of the second battery pack is in an open state, and the second battery pack is a battery pack connected in parallel.

11. The battery pack parallel connection method according to claim 9, characterized in that: Also includes: In response to the second battery pack receiving the parallel connection request instruction, the charging switch on the discharge circuit of the second battery pack is disconnected, and the second battery pack is a parallel connected battery pack.

12. The battery pack parallel connection method according to any one of claim 9, characterized in that: In response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a discharging state, controlling a switch on a charging circuit of the first battery pack to be in an off state, so that the first battery pack performs a discharging parallel connection, further comprising: In response to the first battery pack meeting a second condition, closing a charging switch on a discharge circuit of the first battery pack, and / or, in response to the second battery pack meeting a second condition, closing a charging switch on a charging circuit of the second battery pack, where the second battery pack is a parallel-connected battery pack; The second condition includes at least one of the following: The discharge current of the battery pack is greater than or equal to the second current threshold; The discharge current of the battery pack is less than the second current threshold, and a voltage difference between the voltage of the battery pack and a third voltage is within a third voltage difference range, where the third voltage is the maximum voltage of each battery pack.

13. The battery pack parallel connection method according to claim 12, characterized in that: In response to the first battery pack meeting the first parallel connection condition and the first battery pack being in a discharging state, controlling a switch on a charging circuit of the first battery pack to be in an off state, so that the first battery pack performs a discharging parallel connection, further comprising: In response to the first battery pack meeting a second circulation condition, disconnecting a charging switch and a discharging switch on a discharge circuit of the first battery pack; Among them, the second circulation condition includes that the absolute value of the difference between the current rate of the first battery pack and the second current rate is greater than or equal to the second current rate threshold, wherein the second current rate is the maximum discharge current rate among all the battery packs connected in parallel, and the current rate of the first battery pack includes a charging current rate or a discharging current rate, the charging current rate is a positive value, and the discharging current rate is a negative value.

14. The battery pack parallel connection method according to claim 1, characterized in that: Also includes: detecting whether a charging switch and / or a discharging switch on a charging circuit of a battery pack is on or off, and sending third information, where the third information is used to indicate the on or off status of the charging switch and / or the discharging switch on the charging circuit; and / or, Detect the on / off status of the charging switch and / or the discharging switch on the battery pack discharging circuit, and send fourth information, where the fourth information is used to indicate the on / off status of the charging switch and / or the discharging switch on the discharging circuit.

15. The battery pack parallel connection method according to claim 1, characterized in that: The switch on the discharge circuit responds to the control signal and extends the first time to perform on-off. The switch on the charge circuit responds to the control signal and extends the second time to perform on-off.

16. A battery management system, characterized in that: include at least one processor, and A memory, the memory being communicatively connected to the at least one processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the at least one processor so that the at least one processor can execute the method according to any one of claims 1 to 15.

17. A battery pack comprising: The battery management system as claimed in claim 16.

18. An electrical device, characterized in that: include: load; as well as The battery pack according to claim 17, wherein the battery pack is used to power the load.

19. A storage medium, characterized in that: The storage medium stores computer-executable instructions, and when the computer-executable instructions are executed by a machine, the machine is caused to execute the method according to any one of claims 1 to 15.

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