Battery pack and management method thereof, battery management system and electric equipment

Abstract

A battery pack includes a connector and a battery management system electrically connected to the connector, the connector including a first terminal; the battery management system comprises an integrated circuit, and a current measuring unit, a charging switch and a discharging switch which are arranged on a main circuit. The integrated circuit is configured to determine that the battery pack is in a discharge state in response to the situation that the battery management system is awakened and the level on the first terminal is overturned; in response to the terminal voltage of the main circuit being greater than or equal to the voltage of the battery pack, controlling or keeping the discharge switch on and controlling or keeping the charge switch off; and / or, in response to the situation that the battery management system is awakened and the level on the first terminal is overturned, determining that the battery pack is in a discharge state; and in response to the fact that the terminal voltage of the main circuit is smaller than or equal to the voltage of the battery pack and the fluctuation value of the terminal voltage of the main circuit is within a first range and lasts for a first duration, determining that the battery pack is in a discharging state, controlling or keeping the discharging switch on, and controlling or keeping the charging switch off.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of battery technology, and in particular to battery packs and management methods thereof, battery management systems, and electrical equipment. Background Art

[0002] Multiple battery packs are usually connected in parallel to power electrical equipment to increase capacity and extend the endurance of electrical equipment. For example, multiple parallel battery packs provide power for two-wheeled vehicles to increase the mileage of two-wheeled vehicles. When electrical equipment is working, multiple battery packs are discharged in parallel; when electrical equipment is provided with charging services, multiple battery packs are charged in parallel.

[0003] Due to the differences in the charging and discharging process of each battery pack, the differences in the use of the battery cells, the battery cell performance, and the battery cell aging, it is easy to cause the voltage or capacity of each battery pack to be inconsistent. In this way, when the battery packs are connected in parallel, a circulating current may be generated. Excessive circulating current can easily cause the battery pack to be in current limiting protection, or even damage the battery pack.

[0004] Application Contents

[0005] In view of this, some embodiments of the present application provide a battery pack and a management method thereof, a battery management system and an electrical device to reduce the risk of circulating current.

[0006] In a first aspect, some embodiments of the present application provide a battery pack, which includes a connector and a battery management system electrically connected to the connector, the connector including a first terminal; the battery management system includes a current measuring unit provided on a main circuit, a charging switch and a discharging switch provided on the main circuit, and an integrated circuit. The current measuring unit is configured to measure the current of the battery pack, and the integrated circuit is configured to control the charging switch and / or the discharging switch. The integrated circuit is also configured to: in response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; in response to the terminal voltage of the main circuit being greater than or equal to the voltage of the battery pack, the discharge switch is controlled or maintained to be turned on, and the charging switch is controlled or maintained to be turned off; and / or, in response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; in response to the terminal voltage of the main circuit being less than or equal to the voltage of the battery pack, and the fluctuation value of the terminal voltage of the main circuit is within a first range and lasts for a first time, the discharge switch is controlled or maintained to be turned on, and the charging switch is controlled or maintained to be turned off.

[0007] The battery management system monitors the terminal voltage of the main circuit and the voltage of the battery pack. When the terminal voltage and the voltage of the battery pack meet any one of the first and second conditions above, the discharge switch is controlled or kept open, and the charging switch is controlled or kept off. Compared with turning on the discharge switch and the charging switch at the same time when any one of the first and second conditions above is met, the charging switch in this solution is in a disconnected state, so that the battery pack cannot be charged, reducing the risk of circulating current. In addition, based on the flipping of the level on the first terminal in the connector to wake up the battery management system and determine that the battery pack is in a discharge state, fewer hardware interface requirements are placed, reducing wiring harnesses and reducing the signal pins of the connector, thereby reducing the cost of the battery pack.

[0008] In one or more embodiments, the discharge state includes a first discharge state; I 放1 is less than or equal to the first current threshold, defined as I 放1 is the discharge current when the battery pack is in the first discharge state; wherein the first current threshold is less than zero. The integrated circuit is configured as follows: in response to the battery pack being in the first discharge state, the integrated circuit keeps the discharge switch turned on and controls the charging switch to turn on; or, in response to the battery pack being in the first discharge state and maintaining the second time length, the integrated circuit keeps the discharge switch turned on and controls the charging switch to turn on. In this way, the discharge current passes through the charging switch normally, reducing the risk of the charging switch being damaged due to overheating.

[0009] In one or more embodiments, the discharge state further includes a second discharge state; I 放2 ∈[second current threshold, third current threshold], define I 放2 is the discharge current when the battery pack is in the second discharge state; wherein the second current threshold is less than zero, and the third current threshold is ≤100mA.

[0010] The integrated circuit is configured as follows: in response to the battery pack being in the second discharge state, the integrated circuit keeps the discharge switch open and controls or keeps the charging switch off; or, in response to the battery pack being in the second discharge state and maintaining it for a third time period, the integrated circuit keeps the discharge switch open and controls or keeps the charging switch off.

[0011] In the above embodiment, the second discharge state includes a state where the battery pack is not discharged or is discharged at a relatively small current. When an old battery pack with low power is replaced by a new battery pack, the discharge switch is kept open and the charging switch is controlled or kept turned off to reduce the risk of circulating current caused by charging of other battery packs.

[0012] In one or more embodiments, the integrated circuit is configured to: in response to the current on the main circuit being greater than the maximum charging current of the battery pack and maintaining the fourth time period, control the charging switch to turn off. If the charging current of the battery pack is greater than the maximum charging current of the battery pack and maintains the fourth time period, the battery pack may have a circulating current or feedback, and the charging current of the battery pack is relatively large, and the charging switch of the battery pack is controlled to turn off, thereby reducing the risk of a large current in the main circuit impacting the charging and discharging switch and the battery, and reducing safety hazards.

[0013] In one or more embodiments, the discharge state further includes a third discharge state; the third discharge state is defined as follows: the electric energy discharged by the battery pack is greater than or equal to the sum of the electric energy required by other battery packs and the electric device. The integrated circuit is also configured to: in response to the battery pack being in the third discharge state, control the discharge switch to turn off, and control the charge switch to turn off.

[0014] The electric energy discharged by this battery pack is greater than or equal to the sum of the electric energy required by other battery packs and electrical equipment, indicating that the energy provided by this battery pack is greater than the energy absorbed by the outside world, which may cause the charging current of the battery pack connected in parallel with this battery pack to be too large, thereby controlling both the discharge switch and the charging switch to be turned off for protection and to reduce safety hazards.

[0015] In one or more embodiments, the battery management system further includes: a pre-discharge switch and a resistor, the pre-discharge switch and the resistor are connected in series and then connected in parallel with the discharge switch. The integrated circuit is further configured to: before controlling the discharge switch to be turned on, control the pre-discharge switch to be turned on; in response to satisfying one or more of the following conditions, control the discharge switch to be turned on first, and then control the pre-discharge switch to be turned off:

[0016] i) the terminal voltage of the main circuit is between a first voltage threshold V1 and a second voltage threshold V2;

[0017] Where V1=k1×V 满充 , V2=k2×V 满充 , 0<k1<k2, define V 满充 is the full charge voltage of the battery pack;

[0018] ii) within the fifth time period, the duration for which the discharge current on the pre-discharge switch is less than or equal to the fourth current threshold does not exceed the time period threshold;

[0019] Among them, the fifth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

[0020] In the above embodiment, when the integrated circuit detects that the above condition i) is met, it means that the terminal voltage of the main circuit is reasonable. When the terminal voltage is reasonable, the discharge switch is turned on to reduce the risk of electronic devices in the battery pack being damaged by excessive terminal voltage shock, thereby improving safety. When the integrated circuit detects that the above condition ii) is met, it means that the discharge current flowing through the pre-discharge switch is within a safe range, and no short circuit occurs outside the battery pack. The discharge switch is controlled to be turned on, thereby making the discharge of the battery pack safer. In addition, when the integrated circuit detects that at least one of the above conditions is met, the discharge switch is controlled to be turned on first, and then the pre-discharge switch is controlled to be turned off, so that the battery pack continues to discharge to the outside, thereby avoiding power jams in the load.

[0021] In one or more embodiments, k1∈[0.1,0.7], k2∈[1.0,3.75]. In the above embodiments, the value ranges of k1 and k2 are set based on the full charge voltages of battery packs of different specifications, so that the first voltage threshold V1 and the second voltage threshold V2 are suitable for battery packs of various specifications.

[0022] In one or more embodiments, the integrated circuit is further configured to: in response to the battery management system being awakened, the level on the first terminal is not flipped, and the terminal voltage of the main circuit is less than or equal to the third voltage threshold, control or keep the charging switch open, and control or keep the discharging switch off; define the third voltage threshold to be less than or equal to the maximum charging voltage of the battery pack. In the above manner, the discharge switch of the battery pack is in the disconnected state, so that the battery pack cannot discharge other parallel battery packs, reducing the risk of circulating current in the battery pack. In addition, it does not affect the charging of the battery pack, and improves the parallel charging efficiency.

[0023] In one or more embodiments, the integrated circuit is configured to: determine that the battery pack is in a charging state in response to the current measuring unit measuring that the charging current flows through the main circuit; the charging state includes a first charging state; I 充1 ∈[fifth current threshold, sixth current threshold], define I 充1 is the charging current when the battery pack is in the first charging state; wherein the fifth current threshold is greater than zero, and the sixth current threshold is ≤ the maximum charging current of the battery pack. The integrated circuit is also configured to: in response to the battery pack being in the first charging state, control the discharge switch to open; or, in response to the battery pack being in the first charging state and maintaining the sixth duration, control the discharge switch to open. In this way, the charging current passes through the discharge switch normally, reducing the risk of the discharge switch being damaged due to overheating.

[0024] In one or more embodiments, the integrated circuit is further configured to: in response to the battery pack being in a fully charged state, or in response to the battery pack being in a trickle charging state, or in response to the current of the battery pack being in a current interval and lasting for a seventh period of time, control the charging switch to be disconnected; wherein the current interval is defined as [eighth current threshold, ninth current threshold], the eighth current threshold ∈ [-100mA, 0], the ninth current threshold ∈ (0mA, 600mA]; the trickle charging state is defined: the charging current of the battery pack ∈ [0.05C, 0.1C].

[0025] When the battery pack is fully charged or nearly fully charged when monitored in the above manner, the charging switch is controlled to be turned off, thereby reducing battery health problems caused by the battery pack being fully charged but kept in a charging state for a long time, such as capacity loss, aging or life decay, and reducing safety hazards, such as battery heating or circuit abnormalities.

[0026] In one or more embodiments, the first terminal is configured to wake up the battery management system in response to a voltage level on the first terminal being flipped.

[0027] In one or more embodiments, the connector further includes a positive terminal and a negative terminal, and the positive terminal and the negative terminal are configured to wake up the battery management system in response to a change in a voltage signal between the positive terminal and the negative terminal.

[0028] In one or more embodiments, the current measurement unit is further configured to wake up the battery management system in response to a change in the current signal on the main circuit.

[0029] Compared with the solution that relies on multiple hardware signals or external signals for parallel operation, the solution for waking up the BMS in one or more of the above embodiments has fewer hardware requirements, which is beneficial to reducing wiring harness costs and system complexity.

[0030] In one or more embodiments, the battery management system further includes: a voltage detection circuit electrically connected to the integrated circuit, the voltage detection circuit electrically connected to the positive terminal and / or the negative terminal; the voltage detection circuit is configured to wake up the battery management system in response to a change in the voltage of the positive terminal and / or the negative terminal. The battery management system is awakened by the voltage detection circuit, and then the battery pack is managed in parallel. Compared with relying on communication between battery packs for parallel operation, communication terminals are no longer provided on the connector of the battery pack, and communication circuits are no longer designed and laid out for the battery pack and the power-consuming equipment, thereby reducing the cost of the entire system. In addition, this awakening method allows the battery management system to be awakened even if communication fails, so as to manage the battery pack in parallel.

[0031] In a second aspect, some embodiments of the present application provide a battery pack management method, which is applied to the battery pack provided in the first aspect.

[0032] The method includes: in response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; in response to the terminal voltage of the main circuit being greater than or equal to the voltage of the battery pack, the discharge switch is controlled or kept open, and the charging switch is controlled or kept closed; and / or, in response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; in response to the terminal voltage of the main circuit being less than or equal to the voltage of the battery pack, and the fluctuation value of the terminal voltage of the main circuit is within a first range and lasts for a first time period, the discharge switch is controlled or kept open, and the charging switch is controlled or kept closed.

[0033] In one or more embodiments, the discharge state includes a first discharge state; I 放1 is less than or equal to the first current threshold, defined as I 放1 is the discharge current when the battery pack is in the first discharge state; wherein the first current threshold is less than zero. The method further includes: in response to the battery pack being in the first discharge state, keeping the discharge switch open and controlling the charge switch to be open; or, in response to the battery pack being in the first discharge state and maintaining the second time length, keeping the discharge switch open and controlling the charge switch to be open.

[0034] In one or more embodiments, the discharge state includes a second discharge state; I 放2 ∈[second current threshold, third current threshold], define I 放2 is the discharge current when the battery pack is in the second discharge state; wherein the second current threshold is less than zero and the third current threshold is ≤100mA. The method further includes: in response to the battery pack being in the second discharge state, keeping the discharge switch open and controlling or keeping the charge switch closed; or, in response to the battery pack being in the second discharge state and maintaining the third time length, keeping the discharge switch open and controlling or keeping the charge switch closed.

[0035] In one or more embodiments, the method further includes: in response to the current on the main circuit being greater than the maximum charging current of the battery pack and maintained for a fourth time period, controlling the charging switch to turn off.

[0036] In one or more embodiments, the discharge state further includes a third discharge state; the third discharge state is defined as follows: the electric energy discharged by the battery pack is greater than or equal to the sum of the electric energy required by other battery packs and the electrical device. The method further includes: in response to the battery pack being in the third discharge state, controlling the discharge switch to turn off, and controlling the charge switch to turn off.

[0037] In one or more embodiments, the battery management system further includes: a pre-discharge switch and a resistor, the pre-discharge switch and the resistor are connected in series and then connected in parallel with the discharge switch; before controlling the discharge switch to turn on, the method further includes: controlling the pre-discharge switch to turn on; in response to satisfying one or more of the following conditions, first controlling the discharge switch to turn on, and then controlling the pre-discharge switch to turn off:

[0038] i) the terminal voltage of the main circuit is between a first voltage threshold V1 and a second voltage threshold V2;

[0039] Where V1=k1×V 满充 , V2=k2×V 满充 , 0<k1<k2, define V 满充 is the full charge voltage of the battery pack;

[0040] ii) within the fifth time period, the duration during which the discharge current on the pre-discharge switch is less than or equal to the fourth current threshold does not exceed the time period threshold; wherein the fifth time period is greater than the time period threshold, and the fourth current threshold is a negative value.

[0041] In one or more embodiments, k1∈[0.1,0.7], k2∈[1.0,3.75].

[0042] In one or more embodiments, the method further includes: in response to the battery management system being awakened, the level on the first terminal has not flipped, and the terminal voltage of the main circuit is less than or equal to a third voltage threshold, controlling or keeping the charging switch open, and controlling or keeping the discharging switch open; defining the third voltage threshold to be less than or equal to the maximum allowable charging voltage of the battery pack.

[0043] In one or more embodiments, the method further includes: in response to the current measuring unit measuring that the charging current flows through the main circuit, determining that the battery pack is in a charging state; the charging state includes a first charging state; I 充1 ∈[fifth current threshold, sixth current threshold], define I 充1 is the charging current when the battery pack is in the first charging state; wherein the fifth current threshold is greater than zero, and the sixth current threshold is ≤ the maximum charging current of the battery pack. The method further includes: in response to the battery pack being in the first charging state, controlling the discharge switch to open; or, in response to the battery pack being in the first charging state and maintaining the sixth time length, controlling the discharge switch to open.

[0044] In one or more embodiments, the method further includes: in response to the battery pack being in a fully charged state, or in response to the battery pack being in a trickle charging state, or in response to the current of the battery pack being in a current interval and lasting for a seventh period of time, controlling the charging switch to disconnect; wherein the current interval is defined as [eighth current threshold, ninth current threshold], the eighth current threshold ∈ [-100mA, 0], the ninth current threshold ∈ (0mA, 600mA]; the trickle charging state is defined: the charging current of the battery pack ∈ [0.05C, 0.1C].

[0045] In a third aspect, some embodiments of the present application provide a battery management system, including an integrated circuit and a memory, the memory being used to store instructions, and the integrated circuit being used to execute the aforementioned instructions to implement the battery pack management method according to the second aspect.

[0046] In a fourth aspect, some embodiments of the present application provide an electrical device, including the battery pack in the first aspect or the battery management system in the third aspect.

[0047] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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.

[0049] Figure 1 This is a schematic diagram of the structure of a battery pack in some embodiments of the present application;

[0050] Figure 2 A schematic diagram of a circuit for discharging two battery packs in parallel in some embodiments of the present application;

[0051] Figure 3 A schematic diagram of a control scheme of an integrated circuit in some embodiments of the present application;

[0052] Figure 4 This is a control schematic diagram of a battery pack in a discharge state in some embodiments of the present application;

[0053] Figure 5 This is a control schematic diagram of a battery pack in a discharge state in some embodiments of the present application;

[0054] Figure 6 This is a control schematic diagram of a battery pack in a first discharge state in some embodiments of the present application;

[0055] Figure 7 This is a control schematic diagram of a battery pack in a second discharge state in some embodiments of the present application;

[0056] Figure 8 This is a control schematic diagram of a battery pack in a third discharge state in some embodiments of the present application;

[0057] Fig. 9 This is a control schematic diagram of a battery pack in a certain state in some embodiments of the present application;

[0058] Fig.10 A schematic diagram of a circuit for discharging two battery packs in parallel in some embodiments of the present application;

[0059] Fig.11 A schematic diagram of a control scheme of an integrated circuit in some embodiments of the present application;

[0060] Fig.12 This is a control schematic diagram of a battery pack in a charging state in some embodiments of the present application;

[0061] Fig.13 This is a control schematic diagram of a battery pack in a first charging state in some embodiments of the present application;

[0062] Fig.14 This is a schematic diagram of the structure of a battery pack in some embodiments of the present application;

[0063] Fig.15A and 15B This is a flowchart of a battery pack management method in some embodiments of the present application. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and in detail in combination 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 used to limit the present application.

[0065] It should be noted that when an element is described as "connected" to another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0066] At present, secondary batteries are widely used in electric bicycles, electric motorcycles, drones, electric vehicles and other electrical equipment. The inventors of this application noticed that in order to expand the capacity and improve the endurance of the electrical equipment, two or more battery packs in the electrical equipment will be used in parallel. When the battery packs are connected in parallel, if the voltages between the battery packs are inconsistent or the difference is large, a circulating current will be generated between the battery packs. If the circulating current is large, it may cause irreversible damage to the battery cells.

[0067] In the related technology, during the parallel connection of battery packs, multiple hardware signals are relied on, such as charging detection signals or communication signals. When a signal interface fails, the parallel connection of the battery pack cannot be reliably managed, and the circulation risk cannot be controlled. In addition, relying on multiple hardware signals requires a communication harness to achieve the connection between the battery pack and the power-consuming device or charging device, and a communication circuit needs to be designed, which will increase the cost of the battery pack and the complexity of the system.

[0068] To this end, the embodiments of the present application provide a battery pack and management method thereof, a battery management system and an electric device to reduce the risk of circulating current. A single signal is retained to effectively control the risk of circulating current. In this way, fewer hardware interface requirements are required, which is conducive to reducing wiring harnesses and communication circuits, reducing the cost of battery packs, and facilitating the design and layout of battery management systems.

[0069] Below, in order to facilitate understanding of the solutions of the embodiments of the present application, the structure of the battery pack in some embodiments of the present application is first introduced.

[0070] Battery Pack

[0071] In some embodiments, see Figure 1 The battery pack 100 includes a connector 10, a battery cell module 20 and a BMS 30 (BATTERY MANAGEMENT SYSTEM).

[0072] The connector 10 includes a positive terminal 11 and a negative terminal 12. The positive terminal 11 of the connector 10 is electrically connected to the positive electrode B+ of the battery cell module 20, and the negative terminal 12 of the connector 10 is electrically connected to the negative electrode B- of the battery cell module 20. The positive terminal 11 and the negative terminal 13 are used to transmit electrical energy and power. In this embodiment, the charging terminal and the discharging terminal of the battery pack 100 are the same port scheme, that is, the positive discharge terminal P+ of the battery pack 100 and the positive charging terminal C+ of the battery pack are the same terminal. In other embodiments, the charging terminal and the discharging terminal of the battery pack 100 are different port schemes, that is, the positive discharge terminal P+ of the battery pack 100 and the positive charging terminal C+ of the battery pack 100 are not the same terminal, and the negative discharge terminal P- of the battery pack 100 and the negative charging terminal C- of the battery pack 100 are the same terminal.

[0073] The connector 10 also includes a first terminal 13, which is a signal terminal. The first terminal 13 is electrically connected to the BMS 30. When the connector 10 is connected to an electrical device (not shown), the BMS 30 is electrically connected to the electrical device through the first terminal 13. In this embodiment, the first terminal is used for the interaction of discharge signals between the BMS 30 and the electrical device.

[0074] It is understandable that the main circuit of the battery pack 100 is the power circuit of the battery pack 100, which is used to transmit electrical energy. When the battery pack 100 is discharged, the current path on the main circuit is: positive electrode B+ of the battery cell module 20 → positive electrode discharge terminal P+ → load → negative electrode discharge terminal P- → negative electrode B- of the battery cell module; when the battery pack 100 is charged, the current path on the main circuit is: positive electrode charging terminal C+ → positive electrode B+ of the battery cell module 20 → battery cell module 20 → negative electrode B- of the battery cell module 20 → negative electrode charging terminal C-.

[0075] The battery cell module 20 includes a plurality of battery cells, and the plurality of battery cells are connected in series and / or in parallel.

[0076] In some embodiments, the BMS 30 is presented in the form of a printed circuit board, and switches are set on the BMS 30 circuit board. For example, the charging switch and the discharging switch are set on the current path between the battery module 20 and the connector 10, and the BMS 30 establishes an electrical connection between the battery module 20 and the electrical device (not shown) or cuts off the electrical connection between the battery module 20 and the electrical device by controlling the switch. It is understandable that in some embodiments of the present application, the switch provided on the main circuit is also called a power switch, including: a charging switch and a discharging switch.

[0077] In some embodiments, the BMS 30 includes a current measuring unit 31 , a charging switch 32 , a discharging switch 33 , and an integrated circuit 34 disposed on a main circuit.

[0078] The current measuring unit 31 is used to measure the current of the battery pack 100. For example, the current measuring unit 31 is a shunt resistor or a Hall sensor.

[0079] In some embodiments, the integrated circuit 34 includes an analog front end (AFE) 342, which is electrically connected to the current measurement unit 31 to monitor the current of the battery pack. As a specific example, the AFE 342 is an analog front end chip for monitoring the current on the main circuit and the temperature and voltage of the battery cell.

[0080] The charging switch 32 and the discharging switch 33 are connected in series to the main circuit. In some embodiments, the charging switch 32 and the discharging switch 33 are connected in series between the positive electrode B+ of the battery module 20 and the positive terminal of the connector 10. In other embodiments, the charging switch 32 and the discharging switch 33 are connected in series between the negative electrode B- of the battery module 20 and the negative terminal of the connector 10.

[0081] As a specific implementation, the charging switch 32 and the discharging switch 33 are field effect transistors. The charging switch 32 includes a body diode D1 , and the discharging switch 33 includes a body diode D2 .

[0082] The integrated circuit 34 is configured to control the charging switch 32 and / or the discharging switch 32 to turn on or off the main circuit.

[0083] In some embodiments, the integrated circuit 34 includes a MCU 341 (Micro Controller Unit, MCU) and an AFE 342 connected to the MCU 341 .

[0084] The MCU 341 receives the current of the battery pack 100 monitored by the AFE 342 to determine whether the battery pack 100 is in an overcurrent state, and outputs an instruction to open or close the charge and discharge switch.

[0085] In some embodiments, AFE342 is electrically connected to the charging switch 32 and the discharging switch 33, and MCU341 transmits the above instructions to AFE342. After receiving the above instructions, AFE342 drives the charging and discharging switches to open or close, thereby turning on or off the main circuit.

[0086] In other embodiments, the charge and discharge switch is electrically connected to MCU341 through a drive circuit (not shown). MCU341 transmits the above instructions to the drive circuit. After receiving the above instructions, the drive circuit drives the charge and discharge switch to open or close, thereby turning on or off the main circuit.

[0087] In some embodiments, the BMS 30 includes an AND gate, the input ends of the AND gate are electrically connected to the MCU 341 and the AFE 342, respectively, and the output end of the AND gate is electrically connected to the charge and discharge switch through the drive circuit. In this embodiment, the instructions output by the MCU 341 and the instructions output by the AFE 342 jointly control the opening or closing of the charge and discharge switch.

[0088] In some embodiments, there are multiple charging switches 32 and multiple discharging switches 33 . Multiple charging switches 32 are connected in parallel, and multiple discharging switches 33 are connected in parallel.

[0089] It is understandable that MCU341 also includes input / output ports, timers, analog-to-digital converters (ADCs) or digital-to-analog converters (DACs), etc.

[0090] In the present application, the integrated circuit 34 includes multiple chips or processors and other components, and these components in the integrated circuit 34 cooperate to complete the control of the charging switch 32 and the discharging switch 33. Based on this idea, different control schemes are adopted, which are all protection schemes of the present application or equivalent variation schemes of the present application and belong to the protection scope of the present application.

[0091] In other embodiments, the charging switch 32 and / or the discharging switch 33 is a transistor, a field effect transistor, a relay, an insulated gate bipolar transistor (IGBT), or other controllable switches that can control the main circuit to be turned on or off.

[0092] The integrated circuit 34 controls the switch on the main circuit to open or close, thereby establishing or disconnecting the electrical connection between the battery pack 100 and the electrical device. Figure 1 , the integrated circuit 34 controls the discharge switch 33 and the charge switch 32 on the main circuit to open, and the battery pack 100 establishes an electrical connection with the electrical device. The terminal voltage of the main circuit is lower than the voltage of the battery pack 100, and the battery pack 100 discharges to the outside. The terminal voltage of the main circuit is higher than the voltage of the battery pack 100, and the battery pack 100 is charged.

[0093] In some embodiments of the present application, the battery pack 100 is electrically connected to an electrical device, or the battery pack 100 is electrically connected to a charging device, and the terminal voltage of the main circuit is defined as the voltage difference between the positive terminal 11 and the negative terminal 12 of the connector 10 in the battery pack 100.

[0094] Considering the influence of the terminal voltage of the main circuit, circulating current problems may occur when the battery packs are connected in parallel or during the connection process. Figure 2 As shown, if battery pack 1# and battery pack 2# are connected in parallel to supply power to the vehicle load 200 (e.g., a motor), the power of battery pack 1# is greater than that of battery pack 2#. When the power of battery pack 1# is greater than the power required by the vehicle load 200, battery pack 1# will also charge battery pack 2#, forming a circulation between the battery packs. Figure 2 The charge and discharge switches and the positive and negative terminals are shown, but other components in the battery pack BMS are not shown.

[0095] When developing the parallel technology and products for battery packs, the inventors of this application comprehensively considered: how to reduce the risk of electrical circulating current, improve user experience, reduce wiring harnesses and reduce signal pins of connectors to achieve parallel operation, so as to achieve cost savings. The above technical requirements are met by designing the opening and closing logic of the charging switch and the discharging switch. The technical solution of this application is described in detail below.

[0096] In some embodiments of the present application, the connector of the battery pack only includes a positive terminal, a negative terminal and a first terminal, and does not include other signal terminals, such as a communication terminal, a charging detection terminal, etc., or the connector includes a communication terminal and a charging detection terminal, but the battery management system does not provide a communication circuit corresponding to the communication terminal, and a charging detection circuit corresponding to the charging detection terminal, so that the communication between the battery pack and the electrical equipment cannot be realized, and the function of monitoring whether the battery pack is connected to the charging device cannot be realized. From another perspective, these terminals are regarded as "fake terminals".

[0097] In some embodiments, when the connector is electrically connected to the electrical device, the level on the first terminal flips to wake up the BMS. The level flipping includes: the level flipping from a low level to a high level, or the level flipping from a high level to a low level. In other embodiments, the wake-up of the BMS includes other methods, which will be introduced below, and this application does not limit the wake-up method of the BMS.

[0098] When the battery pack is connected to an electrical device, the level on the first terminal flips. In some embodiments, when the battery pack is disconnected from the electrical device, the first terminal of the connector presents a high level, and when the battery pack is connected to the electrical device, the level of the first terminal is pulled down by the electrical device and flipped to a low level. In some other embodiments, when the battery pack is disconnected from the electrical device, the first terminal of the connector presents a low level; when the battery pack is connected to the electrical device, the level of the first terminal is pulled up by the electrical device and flipped to a high level.

[0099] In this embodiment, the level on the first terminal is reversed, indicating that the battery pack is connected to the power-consuming device and is ready for discharge. Figure 3 After the BMS is awakened, the integrated circuit responds to the level on the first terminal flipping, determines that the battery pack is in a discharging state, and the terminal voltage of the main circuit is greater than or equal to the voltage of the battery pack, controls or keeps the discharge switch open, and controls or keeps the charge switch off.

[0100] Combination Figure 2 For example, the integrated circuit of battery pack 1# responds to the level on the first terminal flipping, indicating that battery pack 1# is connected to the power-consuming device; the terminal voltage V of its main circuit is monitored. p / c (the voltage between the positive terminal P+ / C+ and the negative terminal P- / C-) is greater than or equal to the voltage V of battery pack 1# b1 When Figure 4 As shown, the integrated circuit of the battery pack controls or keeps the discharge switch 33 of battery pack 1# open, and controls or keeps the charge switch 32 closed.

[0101] The terminal voltage of the main circuit is V p / cGreater than or equal to the voltage V of battery pack 1# b1 , one situation is that battery pack 2# is connected in parallel with battery pack 1#, the voltage of battery pack 2# is greater than the voltage of battery pack 1#, the discharge switch 33 of battery pack 2# is turned on or its discharge switch 33 and charging switch 22 are both turned on, then the discharge switch 33 of battery pack 1# is controlled to be turned on. The discharge switch of battery pack 1# is controlled to be turned on because in some scenarios, for example, the electric vehicle needs to accelerate or go uphill, and more electric energy is needed. At this time, the power supply of battery pack 2# alone may be insufficient. First, the discharge switch of battery pack 1# is controlled to be turned on (i.e. closed), so that battery pack 1# can provide electric energy to the outside in time to avoid finding that the power supply of battery pack 2# is insufficient. Then, the delay caused by the opening of the discharge switch of battery pack 1# (including the delay of the software program and the time of the switch closing) is controlled to reduce the jamming of the electric vehicle and improve the user experience. At this time, battery pack 1# discharges to the outside, and the current flows as follows: positive electrode B+ of the cell module → P+ / C+ → load → P- / C- → discharge switch 33 → D2 → negative electrode B- of the cell module. In other scenarios, the power output of battery pack 2# meets the needs of the electric vehicle, battery pack 1# does not discharge temporarily, and there is no current in the main circuit of battery pack 1#. When the power of battery pack 2# is insufficient or the terminal voltage drops to a level close to that of battery pack 1#, battery pack 1# starts to discharge, and there is a discharge current in the main circuit of battery pack 1#.

[0102] In the first case, when the terminal voltage of the main circuit is detected to be greater than or equal to the voltage of battery pack 1#, the discharge switch 33 of battery pack 1# is controlled to open, and the low-voltage battery pack 1# will not charge the high-voltage battery pack 2#, thus reducing the risk of circulating current. In addition, the charging switch 32 of battery pack 1# is controlled to be turned off, and battery pack 2# will not charge battery pack 1#, further reducing the risk of circulating current. In addition, the discharge switch 33 of battery pack 1# is turned on, and battery pack 1# is prepared for discharge in advance, and the battery capacity and power are expanded, so that battery pack 1# can supply power in time when the voltage of battery pack 2# drops to a level close to that of battery pack 1# or the power consumption of the vehicle load 200 increases. If the discharge switch 33 of battery pack 1# is controlled to open only when the voltage of battery pack 2# drops to a level close to that of battery pack 1# or the power consumption of the vehicle load 200 increases, considering the delay in the control response, it may cause untimely power supply, affect the operation of the vehicle load 200, and reduce the user experience. For example, when the vehicle load 200 is traveling at a relatively low speed, battery pack 2# supplies power and battery pack 1# does not. When the vehicle load 200 accelerates, more power is required. The power output by battery pack 2# is insufficient to supply the vehicle load 200. If the discharge switch 33 of battery pack 1# is not opened in advance, power may not be replenished in time, causing the vehicle load 200 to fail to accelerate.

[0103] In some embodiments, please refer to Figure 3The integrated circuit detects that the level on the first terminal is flipped, determines that the battery pack is in a discharging state, the terminal voltage of the main circuit is less than or equal to the voltage of the battery pack, and the fluctuation value of the terminal voltage of the main circuit is within a first range and lasts for a first time period, controls or keeps the discharge switch on, and controls or keeps the charge switch off.

[0104] The terminal voltage of the main circuit is less than or equal to the voltage of the battery pack, which may be due to: no other battery packs are connected in parallel with the battery pack, or other battery packs are connected in parallel with the battery pack, and the voltage of the battery pack is greater than that of other battery packs. Further, after determining that the fluctuation value of the terminal voltage of the main circuit is within the first range and lasts for a first period of time, it means that the terminal voltage of the main circuit is stable, the other battery packs connected in parallel are not in a discharging state or a charging state, and their charging switches are disconnected, and the discharge switch of the battery pack is controlled or kept open, and the battery pack will not charge other battery packs connected in parallel, thereby reducing the risk of circulating current.

[0105] It is understandable that the fluctuation value of the terminal voltage of the main circuit refers to the terminal voltage of the main circuit at the current moment minus the terminal voltage of the main circuit at the previous moment. The voltage difference threshold range set by those skilled in the art based on the specifications of the battery pack and the actual situation of the electrical equipment, for example, the first range is [-1V, 1V] or [-2V, 2V]. The time range set by those skilled in the art based on the actual situation of the battery pack and the electrical equipment, for example, the first time length is 1s, 2s, 3s or 5s, etc.

[0106] Combination Figure 2 For example, when the integrated circuit of battery pack 1# detects the terminal voltage V p / c Less than or equal to the voltage V of battery pack 1# b1 , and the terminal voltage of the main circuit V p / c The fluctuation value is within [-1V, 1V] and lasts for 1s, such as Figure 5 As shown, the discharge switch 33 of battery pack 1# is controlled or kept open, and the charging switch 32 is controlled or kept closed. Considering that battery pack 2# is not connected in parallel or has been connected in parallel but the voltage of battery pack 2# is lower than that of battery pack 1#, when the vehicle load 200 has a power demand, battery pack 1# is discharged, and the current path is: positive electrode B+ of battery cell module 20→P+ / C+→load→P- / C-→discharge switch 33→D2→negative electrode B- of battery cell module 20. If the vehicle load 200 has no power demand, battery pack 1# will not be discharged temporarily.

[0107] In the second case, due to the terminal voltage V p / c Less than or equal to the voltage V of battery pack 1# b1 , and the terminal voltage of the main circuit V p / cThe fluctuation value of is within the first range and lasts for the first time, indicating that the terminal voltage of the main circuit is stable, battery pack 2# is not in parallel or is in parallel but not in charging state, and its charging switch is in the off state. Based on this, the discharge switch 33 of battery pack 1# is turned on, and battery pack 1# will not charge battery pack 2#, thereby reducing the risk of circulating current. In addition, the charging switch 32 of battery pack 1# is turned off, and battery pack 2# will not charge battery pack 1#, further reducing the risk of circulating current.

[0108] The battery management system monitors the terminal voltage of the main circuit and the voltage of the battery pack. When the terminal voltage and the voltage of the battery pack meet any one of the first and second conditions above, the discharge switch is controlled or kept open, and the charging switch is controlled or kept off. Compared with turning on the discharge switch and the charging switch at the same time when any one of the first and second conditions above is met, the charging switch in this solution is in a disconnected state, so that the battery pack cannot be charged, reducing the risk of circulating current. In addition, based on the flipping of the level on the first terminal in the connector to determine that the battery pack is in a discharge state, fewer hardware interface requirements are placed, reducing wiring harnesses and reducing the signal pins of the connector, thereby reducing the cost of the battery pack.

[0109] It is understandable that when the battery pack leaves the factory, the status of the discharge switch and the charging switch have default settings. In some embodiments, for a battery pack with a blind release setting, when the battery pack leaves the factory, the discharge switch is turned on and the charging switch is turned off by default. When the integrated circuit detects any of the above two situations, it keeps the discharge switch on and keeps the charging switch off. In some embodiments, for a battery pack with a blind release and blind charging setting, when the battery pack leaves the factory, the discharge switch and the charging switch are both turned on by default. When the integrated circuit detects any of the above two situations, it keeps the discharge switch on and controls the charging switch to be turned off. In some embodiments, when the battery pack leaves the factory, the discharge switch and the charging switch are both turned off by default. When the integrated circuit detects any of the above two situations, it controls the discharge switch to be turned on and keeps the charging switch off. It can be seen that the scheme of the integrated circuit controlling the charging switch and the discharge switch in this scheme is applicable to battery packs with a variety of default settings and has a wide range of applications.

[0110] After completing the above control, the discharge path on the main circuit is turned on, and the current measurement unit measures the current on the main circuit, that is, the current of the battery pack. The integrated circuit determines the state of the battery pack based on the current of the battery pack. Based on the state of the battery pack, the discharge switch and / or the charging switch are further controlled to reduce the risk of circulating current.

[0111] In some embodiments, the discharge state includes a first discharge state. Definition I 放1 is the discharge current of the battery pack when it is in the first discharge state, I 放1 is less than or equal to the first current threshold.

[0112] In the present application, the first current threshold is less than zero, and is used to distinguish between the first discharge state and other states in which a larger current is used to supply power to a first load with high power consumption such as a motor. Exemplarily, the first current threshold is -500mA, -700mA or -1A, etc. Those skilled in the art set the first current threshold according to the specific situation of the first load in the electrical equipment. It is understandable that the first current threshold of the battery pack applied to an electric two-wheeled vehicle (e.g., -500mA) is greater than the first current threshold of the battery pack applied to an electric vehicle (e.g., -1A).

[0113] When the integrated circuit monitors that the current of the battery pack is less than or equal to a first negative current threshold, it is determined that the battery pack is in a first discharge state, and the battery pack supplies power to a first load with relatively large power consumption in the electrical device.

[0114] In some embodiments, the integrated circuit is configured to keep the discharge switch open and control the charge switch to open in response to the battery pack being in the first discharge state.

[0115] In some other embodiments, the integrated circuit is configured to keep the discharge switch turned on and control the charging switch to turn on in response to the battery pack being in the first discharge state and maintaining the second time length. That is, the integrated circuit detects that the battery pack is in the first discharge state and maintains the second time length, and the battery pack normally supplies power to the first load with large power consumption. Among them, setting the second time length is conducive to reducing misjudgment. The second time length is specifically set based on the battery pack or the power-consuming device. Exemplarily, the second time length is 1s or 2s, etc.

[0116] When battery pack 1# is normally supplying power to the first load with large power consumption, please refer to Figure 6 , keep the discharge switch 33 open, control the charging switch 32 to open, so that the discharge current passes through the charging switch 32 normally, reducing the risk of the charging switch 32 being damaged due to overheating.

[0117] Taking an electric two-wheeled vehicle as an example of an electrical equipment, in some operating conditions, the electric two-wheeled vehicle is ignited and powered on to start driving, and the battery pack is in the first discharge state for supplying power to the first load with larger power consumption. In other operating conditions, the electric two-wheeled vehicle parks after normal driving, for example, stops to talk to someone, but does not shut down the engine, and the battery pack supplies power to a second load such as an instrument panel with smaller power consumption. In some other operating conditions, the electric two-wheeled vehicle stops driving, shuts down the engine, and the battery pack does not discharge at all and is in a power-off state. In some other operating conditions, the electric two-wheeled vehicle is ignited and powered on, but does not drive, and the battery pack supplies power to a second load such as an instrument panel with smaller power consumption.

[0118] In some embodiments, in order to identify the operating condition where the battery pack is supplying power to a second load such as a dashboard with low power consumption or a condition where there is no discharge at all, a current threshold interval is set: [second current threshold, third current threshold].

[0119] I 放2 ∈[second current threshold, third current threshold], define I 放2 It is the discharge current when the battery pack is in the second discharge state. It is understandable that in some embodiments of the present application, the second discharge state includes a state where the battery pack supplies power to a second load with less power consumption in the power-consuming device or a state where the battery pack is not discharged at all.

[0120] The second current threshold is less than zero, and the second current threshold is used as an indicator to distinguish the current threshold when the battery pack supplies power to a first load with large power consumption, such as a motor, with a larger current and supplies power to a second load with small power consumption, such as an instrument panel, with a smaller current. When the battery pack supplies power to a first load with small power consumption, such as an instrument panel, there is a discharge current, and the discharge current value is relatively small. In some embodiments, the second current threshold is greater than or equal to the first current threshold in the above embodiments.

[0121] The technicians in this field set the second current threshold value based on actual experience and the actual situation of the battery pack supplying power to the electrical equipment. For example, if the electrical equipment is an electric two-wheeled vehicle, and the battery pack supplies power to a second load with relatively low power consumption, such as the instrument panel on the electric two-wheeled vehicle, the discharge current value is about -400mA, and the second current threshold value is determined to be -500mA. If the electrical equipment is an electric vehicle, and the battery pack supplies power to more electronic devices with relatively low power consumption on the electric vehicle, such as the central control system, air conditioning, audio or electric windows, the discharge current value is approximately close to -1A, and the second current threshold value is determined to be -1A, -1.5A or -2A.

[0122] The third current threshold is less than or equal to 100 mA. In some embodiments, the third current threshold is used as an indicator: a current threshold for distinguishing a charging current from a no current.

[0123] Taking into account the accuracy of the current measurement unit or the current zero drift, the threshold for distinguishing the discharge current is defined as a negative value, such as -50mA or -100mA. Exemplarily, when the current of the battery pack is less than or equal to -100mA, it is determined that the discharge current flows through the main circuit. The threshold for distinguishing the charging current is defined as a positive value, such as 50mA or 100mA. Exemplarily, when the current of the battery pack is greater than or equal to 100mA, it is determined that the charging current flows through the main circuit. When the current of the battery pack is between ±100mA, it is determined that no current flows through the main circuit.

[0124] In some embodiments, the third current threshold ∈(second current threshold, 100mA]. Exemplarily, the third current threshold is -50mA, -10mA, 0mA, 10mA, 50mA, 80mA or 100mA, etc. In this embodiment, taking into account the measurement error and the current zero drift caused by temperature change or unstable battery pack voltage, the third current threshold is limited to be less than or equal to 100mA, so that the third current threshold is accurate, which is conducive to accurately monitoring that the battery pack is in the second discharge state, turning off the charging switch in time, and reducing the risk of circulating current.

[0125] In some embodiments, the integrated circuit is configured to keep the discharge switch open and control or keep the charging switch off in response to the battery pack being in the second discharge state. In some embodiments, the integrated circuit is configured to keep the discharge switch open and control or keep the charging switch off in response to the battery pack being in the second discharge state and maintaining a third time length. Among them, setting the third time length is conducive to reducing misjudgment, and the third time length is specifically set based on the battery pack or the electrical device. For example, the third time length is 1s or 2s.

[0126] See also Figure 7 When the integrated circuit monitors that the discharge current value of battery pack 1# is between the second current threshold and the third current threshold, it indicates that the battery pack is discharging with a smaller current or not discharging, and it is determined that the battery pack is in the second discharge state (not discharging or discharging with a smaller current).

[0127] In the second discharge state, taking the electrical equipment as a two-wheeled vehicle as an example, the corresponding working conditions include: when the two-wheeled vehicle is parked or just started, the battery pack only supplies power to devices with low power consumption such as the instrument panel, or the two-wheeled vehicle is turned off and powered off. When the electrical equipment is in these working conditions, this battery pack may be connected in parallel with other battery packs. When it is detected that the battery pack is in the second discharge state or the battery pack is in the second discharge state and maintains the third time, the discharge switch is kept open and the charging switch is controlled or kept turned off to reduce the risk of circulating current caused by other battery packs being connected in parallel with this battery pack and charging this battery pack.

[0128] The following example is used to illustrate: If a rider finds that a battery pack is low on power, he drives to a battery swap station, parks the vehicle to replace the battery, or inserts a battery pack into the battery compartment of the vehicle. At this time, the two-wheeled vehicle may be in a powered-off or powered-on state. When a new battery pack is connected, it often has a higher voltage. If the charging switch of the current battery pack is not turned off, the new battery pack may charge the current battery pack, forming a circulation. Therefore, if Figure 7As shown, in this solution, when it is found that battery pack 1# is in the second discharge state or in the second discharge state and maintained for the third time, the charging switch 32 of the battery pack is controlled or kept turned off, thereby reducing the risk of circulating current due to the charging of the battery pack by the new battery pack. In addition, keeping the discharge switch 33 open does not affect the battery pack to continue to supply power to the outside.

[0129] In some scenarios, if battery pack 1# discharges to an electrical device and / or battery pack 2#, the discharge switch of battery pack 1# is turned on, or both the discharge switch and the charge switch of battery pack 1# are turned on. Considering that in the case where the energy provided by battery pack 1# is greater than the energy absorbed from the outside, battery pack 1# charging battery pack 2# may cause the charging current of battery pack 2# to be too large, in some embodiments, the discharge state of the battery pack is set to include a third discharge state. Definition of the third discharge state: The electrical energy provided by the battery pack to the outside is greater than or equal to the sum of the electrical energy required by other battery packs and electrical devices.

[0130] When the integrated circuit detects that the electric energy discharged by the battery pack is greater than or equal to the sum of the electric energy required by other battery packs and electrical devices, the integrated circuit is also configured to: control the discharge switch to turn off, and control the charging switch to turn off. Figure 8 As shown, battery pack 1# is in the third discharge state, and the discharge switch 33 and the charge switch 32 of battery pack 1# are both turned off.

[0131] In this embodiment, the electric energy discharged by the battery pack is greater than or equal to the sum of the electric energy required by other battery packs and electrical equipment, indicating that the energy provided by the battery pack is greater than the energy absorbed from the outside, which may cause the charging current of the battery pack connected in parallel with the battery pack to be too large, thereby controlling both the discharge switch and the charging switch to be turned off for protection and to reduce safety hazards.

[0132] Taking the electric vehicle as an example, some embodiments of the present application include some scenarios, in which the charging switch and the discharging switch of the battery pack are both turned on during the driving of the electric vehicle, and when the electric vehicle brakes or passes through a downhill section, energy is recovered and converted into electrical energy, and the generated feedback current is used to charge the battery pack. At this time, the battery pack is in a charging state. That is, the battery pack is charged during the driving of the electric vehicle.

[0133] In other scenarios, when the driver finds that the power of a battery pack is too low while the electric vehicle is driving, the electric vehicle may be stopped for a short time to replace the battery pack with low power among multiple battery packs. When a new battery pack is connected in parallel with the current battery pack, and the power or voltage of the new battery pack is greater than the power or voltage of the current battery pack, and the power provided by the new battery pack is greater than the power required by the electric vehicle, the new battery pack charges the current battery pack, generating a circulating current. In this case, the current battery pack will also be charged.

[0134] In some embodiments of the present application, a feedback current or a circulating current that is less than or equal to the tolerable charging current of the battery pack is allowed. In this case, the present battery pack is charged by a new battery pack within the allowable charging current range.

[0135] In some other embodiments of the present application, the feedback current or circulating current is greater than the battery pack's tolerable charging current. In a short period of time, the electrical energy they provide to the battery pack is within the battery pack's tolerable capacity, that is, a brief impact on the battery pack is allowed.

[0136] In some other embodiments of the present application, when the feedback current or the circulating current is greater than the tolerable charging current and the electrical energy provided by the feedback current or the circulating current to the battery pack exceeds the tolerable capacity of the battery pack, it may cause the battery cell to overheat or polarize, causing damage to the battery pack. This situation is not allowed.

[0137] In some embodiments of the present application, the tolerable charging current is determined based on the overcurrent capability of the device or battery cell in the battery pack. When the charging current is greater than the tolerable charging current, the battery cell or device in the battery pack has an extreme case of being broken down.

[0138] Based on the above considerations, in some embodiments, from the perspective of the maximum charging current and the fourth duration of the battery pack, it is monitored whether the electric energy provided by the feedback current or the circulating current to the battery pack exceeds the tolerance of the battery pack. The maximum charging current refers to the maximum continuous current allowed when the battery pack is charged. Those skilled in the art will look up and determine the maximum charging current in the product manual or nameplate of the battery pack. The fourth duration is related to the magnitude of the maximum charging current. Setting the fourth duration and monitoring from the perspective of electric energy is beneficial to the accuracy of monitoring.

[0139] See also Fig. 9 , the integrated circuit of battery pack 1# detects that the charging current on its main circuit is greater than the maximum charging current of battery pack 1# and lasts for the fourth time period, and the battery pack 1# may have a circulation or feedback, and the charging current of battery pack 1# is large, so the charging switch 32 of battery pack 1# is controlled to be turned off. Disconnecting the charging path of this battery pack 1# reduces the risk of large current in the main circuit impacting the charging and discharging switch and the battery, and reduces safety hazards.

[0140] In some embodiments, see Fig.10 The BMS 30 further includes a pre-discharge switch 35 and a resistor 36 . The pre-discharge switch 35 and the resistor 36 are connected in series and then connected in parallel with the discharge switch 33 .

[0141] As a specific implementation, the pre-discharge switch 35 is a field effect transistor, and the pre-discharge switch 35 includes a body diode D5. In some other embodiments, the pre-discharge switch 35 is connected in parallel with the diode D5.

[0142] Resistor 36 is used as a current limiter to limit the discharge current. For example, resistor 36 is a thermistor. When the battery pack is discharged to the outside, if the discharge switch 33 in the discharge loop is directly closed, the battery pack will output a large discharge current, and the large current may damage the discharge switch 33 and the charging switch 32. Therefore, when the battery pack is ready to discharge, BMS30 first controls the pre-discharge switch 35 to close, controls or keeps the discharge switch 33 off, and the discharge current flows through resistor 36 to limit the discharge current and reduce the risk of damage to the discharge switch 33 and the charging switch 32. In addition, a smaller discharge current has less impact on the load and a smaller risk of circulating current.

[0143] In response to at least one of the following conditions being met, the integrated circuit 35 first controls the discharge switch 33 to open, and then controls the pre-discharge switch 35 to close, so that the terminal voltage of the main circuit tends to be consistent with the battery pack voltage, reducing the impact of the terminal voltage on the battery pack; on the other hand, the battery pack continues to discharge to the outside to avoid power jams in the load. The conditions include:

[0144] i) Terminal voltage V of the main circuit p / c between a first voltage threshold V1 and a second voltage threshold V2;

[0145] Where V1=k1×V 满充 , V2=k2×V 满充 , 0<k1<k2, define V 满充 is the full charge voltage of the battery pack;

[0146] ii) within the fifth time period, the duration during which the discharge current on the pre-discharge switch 35 is less than or equal to the fourth current threshold does not exceed the time period threshold;

[0147] Among them, the fifth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

[0148] For the above condition i), when the terminal voltage V p / c ∈[k1×V 满充 , k2×V 满充 ], indicating that the terminal voltage of the main circuit is reasonable. It is safer to first control the discharge switch 33 to open and then control the pre-discharge switch 35 to close. It can be understood that the terminal voltage of the main circuit is reasonable, and the terminal voltage is within the tolerance range of the battery pack, such as within the tolerance range of the battery module, the switch, and some other electronic devices.

[0149] If the terminal voltage of the main circuit exceeds the second voltage threshold V2, opening the discharge switch 33 may cause the devices in the battery pack to be damaged due to the impact of the excessively high terminal voltage, for example, the device may be short-circuited, broken down, or open-circuited. In the event of a short circuit in the device, the excessively high terminal voltage impacts the battery cells in the battery pack, causing severe polarization of the battery cells and increased temperature rise, posing a safety hazard; or, the charging and discharging of the battery pack is uncontrolled, posing a safety hazard. In the event of an open circuit in the device, the working process of the battery pack is affected.

[0150] In some embodiments, k1∈[0.1,0.7], k2∈[1.0,3.75]. It is understandable that the value ranges of k1 and k2 are set based on the full charge voltages of battery packs of different specifications, so that the first voltage threshold V1 and the second voltage threshold V2 are suitable for battery packs of various specifications.

[0151] When the integrated circuit detects that the above condition i) is met, it means that the terminal voltage of the main circuit is reasonable, and the discharge switch is controlled to open. When the terminal voltage is reasonable, the discharge switch is turned on, so that the risk of breakdown of electronic devices in the battery pack is reduced, which is safer.

[0152] For the above condition ii), within the fifth time period, for example 1s or 2s, the duration of the discharge current on the pre-discharge switch being less than or equal to the fourth current threshold does not exceed the time threshold, for example, the fourth current threshold is -1A or -2A, and the fifth time period is 100ms, 250ms or 500m, indicating that the discharge current on the pre-discharge switch is small and no external short circuit occurs. The discharge switch 33 is first controlled to be opened, and then the pre-discharge switch 35 is controlled to be turned off.

[0153] That is, when the integrated circuit detects that the above condition ii) is met, it means that the discharge current flowing through the pre-discharge switch is small and no short circuit occurs outside the battery pack. Then the discharge switch is controlled to open, thereby making the discharge of the battery pack safer.

[0154] In some scenarios, battery pack 1# and battery pack 2# are charged in parallel by charging device 300. In some embodiments, see Fig.11 In response to the level on the first terminal not flipping and the terminal voltage of the main circuit being less than or equal to a third voltage threshold, the integrated circuit controls or keeps the charging switch turned on and controls or keeps the discharging switch turned off. The third voltage threshold is less than or equal to the maximum charging voltage of the battery pack.

[0155] As can be seen from the above, when the connector of the battery pack is not electrically connected to the power-consuming device, the level on the first terminal will not flip. If the power-consuming device is not electrically connected, the possible situations are: the battery pack is connected to the charging device, or the battery pack is not electrically connected to the external device, then it is determined that the battery pack is not in a discharging state. Further monitor whether the terminal voltage of the main circuit is less than or equal to the third voltage threshold.

[0156] The third voltage threshold is less than or equal to the maximum charging voltage of the battery pack. The maximum charging voltage refers to the highest voltage value that the battery pack withstands during the charging process. The maximum charging voltage is obtained from the battery pack label, battery module label, packaging, user manual, instruction manual, advertisement, marketing or other supporting documents. If the terminal voltage of the main circuit is less than or equal to the third voltage threshold, it means that the terminal voltage of the main circuit is within the safe range. Then try to control or keep the charging switch open, and control or keep the discharging switch off, so as to further determine the state of the battery pack based on the current.

[0157] like Fig.12 As shown, the level on the first terminal of battery pack 1# has not flipped, and the terminal voltage of the main circuit is less than or equal to the third voltage threshold, and the integrated circuit of battery pack 1# controls or keeps the charging switch 32 turned on, and controls or keeps the discharging switch 33 turned off. The discharging switch 33 of battery pack 1# is in the disconnected state, so that battery pack 1# cannot discharge and cannot charge battery pack 2#, reducing the risk of circulating current in the battery pack. In addition, it does not affect the charging of battery pack 1#, and improves the parallel charging efficiency.

[0158] After completing the above control, the charging path on the main circuit is turned on, and the current measurement unit measures the charging current flowing through the main circuit, determining that the battery pack is in a charging state, which facilitates further control of the charging switch and / or the discharging switch to improve charging safety.

[0159] In some embodiments, the charging state includes a first charging state. Definition I 充1 is the charging current when the battery pack is in the first charging state, I 充1 ∈[fifth current threshold, sixth current threshold], where the fifth current threshold is greater than zero and the sixth current threshold is ≤ the maximum charging current of the battery pack.

[0160] The fifth current threshold is greater than zero, and the fifth current threshold serves as an indicator: a current threshold for distinguishing a charging current from no current. Taking into account the accuracy of the current measurement unit or the current zero drift, the threshold for distinguishing the discharge current is defined as a negative value, such as -50mA or -100mA. Exemplarily, when the current of the battery pack is less than or equal to -50mA, it is determined that a discharge current is flowing through the main circuit. The threshold for distinguishing the charging current is defined as a positive value, such as 50mA or 100mA. Exemplarily, when the current of the battery pack is greater than or equal to 50mA, it is determined that a charging current is flowing through the main circuit. When the current of the battery pack is between ±50mA, it is determined that no current is flowing through the main circuit.

[0161] In some embodiments, the fifth current threshold is determined with reference to the above threshold for distinguishing the charging current. Exemplarily, the fifth current threshold is greater than or equal to the above threshold for distinguishing the charging current. For example, the fifth current threshold is 50mA or 100mA, etc.

[0162] The sixth current threshold is less than or equal to the maximum charging current of the battery pack. The maximum charging current refers to the maximum continuous current allowed when the battery pack is charged. The maximum charging current is obtained from the battery pack label, battery module label, packaging, user manual, instruction manual, advertisement, marketing or other supporting documents.

[0163] I 充1 ∈[fifth current threshold, sixth current threshold], indicating that the battery pack is charged at a current not exceeding the maximum charging current and is in the first charging state. When the integrated circuit detects that the current of the battery pack is greater than or equal to the fifth current threshold and less than or equal to the sixth current threshold, it is determined that the battery pack is in the first charging state, that is, the normal charging state.

[0164] In some embodiments, the integrated circuit is configured to control the discharge switch to open in response to the battery pack being in the first charging state. In some other embodiments, the integrated circuit is configured to control the discharge switch to open in response to the battery pack being in the first charging state and maintaining the sixth time length. Among them, setting the sixth time length is conducive to reducing misjudgment. The sixth time length is specifically set based on the battery pack. Exemplarily, the sixth time length is 1s or 2s, etc.

[0165] When battery pack 1# is charged normally, please refer to Fig.13 , keep the charging switch 32 open, control the discharging switch 33 to open, so that the charging current passes through the discharging switch 33 normally, reducing the risk of the discharging switch 33 being damaged due to overheating.

[0166] As the charging process progresses, the power level of the battery pack increases. In some embodiments, in order to reduce battery health problems (such as capacity loss, aging, or life attenuation) or safety hazards (such as heating or circuit abnormality, etc.) caused by the battery pack being fully charged but remaining in a charging state for a long time, the integrated circuit controls the charging switch to turn off when at least one of the following conditions is detected:

[0167] 1) The battery pack is fully charged;

[0168] 2) The battery pack is in a trickle charge state. The trickle charge state is defined as: the charging current of the battery pack∈[0.05C, 0.1C];

[0169] 3) The current of the battery pack is in the current interval and lasts for the seventh period of time, and the current interval is defined as [eighth current threshold, ninth current threshold], the eighth current threshold ∈ [-100mA, 0], and the ninth current threshold ∈ (0mA, 600mA].

[0170] The battery pack reaches its maximum capacity, indicating that the battery pack is in a fully charged state. The charging switch is controlled to be turned off, thereby reducing battery health problems or safety hazards caused by the battery pack being fully charged but remaining in a charged state for a long time.

[0171] The integrated circuit detects that the charging current is in the range of [0.05C, 0.1C], indicating that the battery pack is charged at a low current and enters a trickle charging state. The battery pack is in a trickle charging state, indicating that the battery pack is close to being fully charged. Therefore, the battery pack is detected to be in a trickle charging state, and the charging switch is controlled to be turned off, reducing the battery health problems or safety hazards caused by the battery pack being fully charged but kept in a charging state for a long time.

[0172] Similarly, the current interval [eighth current threshold, ninth current threshold] is set, the eighth current threshold ∈ [-100mA, 0], the ninth current threshold ∈ (0mA, 600mA]; the integrated circuit detects that the current of the battery pack is within the current interval. Possible situations: there is no current or the current is small in the main circuit of the battery pack, indicating that the battery pack is not charged (for example, disconnected from the charging device), or the battery pack may be close to full charge. Thus, the charging switch is controlled to be turned off, reducing the battery health problems or safety hazards caused by the battery pack being fully charged but remaining in the charging state for a long time. Among them, setting the seventh time length is conducive to reducing misjudgment. The seventh time length is specifically set based on the battery pack. Exemplarily, the seventh time length is 1s or 2s, etc.

[0173] In some embodiments, the first terminal is configured to wake up the battery management system in response to a flip in the level on the first terminal. For example, after the battery pack is connected to the power-consuming device, the first terminal flips from a low level to a high level or from a high level to a low level, thereby waking up the battery management system and further determining that the battery pack is in a discharge state.

[0174] In some embodiments, the positive terminal and the negative terminal are configured to respond to a change in the voltage signal between the positive terminal and the negative terminal to wake up the battery management system. For example, when a battery pack is placed in a battery compartment of an electrical device, the connector of the battery pack is plugged into the connector in the battery compartment, and the voltage signal on the positive terminal of the connector of the battery pack changes.

[0175] For example, the low level changes to a high level, thereby waking up the battery management system. For another example, when the battery pack is connected to a charging device, the voltage of the positive terminal increases, and the voltage signal between the positive terminal and the negative terminal changes, waking up the battery management system.

[0176] In some embodiments, the current measurement unit is configured to wake up the battery management system in response to a change in the current signal on the main circuit. When the battery pack leaves the factory, the discharge switch is turned on by default. When the battery pack is connected to an electrical device, the current measurement unit senses a change in the current signal of the main circuit and wakes up the battery management system to perform parallel management of the battery pack.

[0177] Compared with the solution relying on multiple hardware signals or external signals for parallel operation, the method of waking up the BMS in one or more of the aforementioned embodiments has fewer hardware requirements and is beneficial to reducing wiring harness costs and system complexity.

[0178] In some embodiments, the battery management system further comprises: a voltage detection circuit electrically connected to the integrated circuit, the voltage detection circuit electrically connected to the positive terminal and / or the negative terminal. The voltage detection circuit is configured to wake up the battery management system in response to a change in the voltage of the positive terminal and / or the negative terminal.

[0179] like Fig.14 As shown, the voltage detection circuit includes a first voltage detection circuit and / or a second voltage detection circuit. In some embodiments, the voltage of the negative terminal is detected by the first voltage detection circuit, and a first detection signal for characterizing the voltage of the negative terminal is output to the integrated circuit, so that when the voltage of the negative terminal changes, the first detection signal changes, and the integrated circuit is awakened, that is, the battery management system is awakened. In other embodiments, the voltage of the positive terminal is detected by the second voltage detection circuit, and a second detection signal for characterizing the voltage of the positive terminal is output to the integrated circuit, so that when the voltage of the positive terminal changes, the second detection signal changes, and the integrated circuit is awakened, that is, the battery management system is awakened.

[0180] The first voltage detection circuit and the second voltage detection circuit can refer to the relevant description in patent application CN115313582A, which will not be introduced in detail here.

[0181] The battery management system is awakened by the voltage detection circuit to manage the battery packs in parallel. Compared with relying on communication between battery packs for parallel operation, communication terminals are no longer provided on the connector of the battery pack, and communication circuits are no longer designed and laid out for the battery pack and the electrical equipment, thereby reducing the cost of the entire system. In addition, this awakening method allows the battery management system to be awakened even if communication fails, so as to manage the battery packs in parallel.

[0182] Battery Pack Management Method

[0183] Some embodiments of the present application also provide a battery pack management method, which is applied to the battery pack in the aforementioned embodiment. The battery pack management method is consistent with the logic of the integrated chip controlling the charging switch and / or the discharging switch in the aforementioned embodiment. For the specific process, please refer to Fig.15A and Fig. 15B , I will not go into details here.

[0184] Battery Management System

[0185] Based on the same inventive concept, an embodiment of the present application also provides a battery management system, including an integrated circuit and a memory, the memory is used to store instructions, and the integrated circuit is used to execute the aforementioned instructions to implement the battery pack management method in the above embodiment.

[0186] The integrated circuit and the memory are described in the above battery pack embodiment. It is understandable that in other embodiments, the battery management system also includes other components, which can be referred to the description of the battery management system in the above battery pack embodiment, and will not be described in detail here.

[0187] Electrical equipment

[0188] Based on the same inventive concept, an embodiment of the present application further provides an electrical device, including the battery pack in the above embodiment, or the battery management system in the above embodiment.

[0189] The electrical equipment of the present application is not particularly limited. In some embodiments, the electrical equipment may include energy storage systems, electric motorcycles, electric bicycles, electric tricycles, electric vehicles, power tools, sweeping robots, drones, electric vacuum cleaners, automated guided vehicles (AGVs), uninterruptible power supplies (UPSs), etc.

[0190] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A battery pack, comprising: A connector including a first terminal; A battery management system electrically connected to the connector includes: A current measuring unit, provided on the main circuit and configured to measure the current of the battery pack; A charging switch and a discharging switch provided on the main circuit; an integrated circuit electrically connected to the current measuring unit, configured to control the charging switch and / or the discharging switch; Characterized in that the integrated circuit is further configured as: In response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; In response to the terminal voltage of the main circuit being greater than or equal to the voltage of the battery pack, controlling or keeping the discharge switch open, and controlling or keeping the charge switch closed; and / or, In response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; In response to the terminal voltage of the main circuit being less than or equal to the voltage of the battery pack, and the fluctuation value of the terminal voltage of the main circuit being within a first range and lasting for a first time period, the discharge switch is controlled or kept open, and the charge switch is controlled or kept closed.

2. The battery pack according to claim 1, characterized in that: The discharge state includes a first discharge state; I 放1 is less than or equal to the first current threshold, defined as I 放1 is the discharge current of the battery pack when it is in the first discharge state; Wherein, the first current threshold is less than zero; The integrated circuit is configured to: In response to the battery pack being in the first discharge state, the integrated circuit keeps the discharge switch turned on and controls the charge switch to turn on; or, In response to the battery pack being in the first discharge state and maintaining the state for a second time period, the integrated circuit keeps the discharge switch turned on and controls the charge switch to turn on.

3. The battery pack according to claim 1 or 2, characterized in that: The discharge state also includes a second discharge state; I 放2 ∈[second current threshold, third current threshold], define I 放2 is the discharge current of the battery pack when it is in the second discharge state; Wherein, the second current threshold is less than zero, and the third current threshold is ≤100mA; The integrated circuit is configured to: In response to the battery pack being in the second discharge state, the integrated circuit keeps the discharge switch open and controls or keeps the charge switch off; or, In response to the battery pack being in the second discharge state and maintaining the state for a third time period, the integrated circuit keeps the discharge switch open and controls or keeps the charge switch closed.

4. The battery pack according to claim 2, characterized in that: The integrated circuit is configured to: In response to the current on the main circuit being greater than the maximum charging current of the battery pack and being maintained for a fourth time period, the charging switch is controlled to be turned off.

5. The battery pack according to claim 1 or 2, characterized in that: The discharge state also includes a third discharge state; The third discharge state is defined as follows: the electric energy discharged by the battery pack is greater than or equal to the sum of the electric energy required by other battery packs and the electric device; The integrated circuit is further configured to: In response to the battery pack being in the third discharge state, the discharge switch is controlled to be turned off, and the charge switch is controlled to be turned off.

6. The battery pack according to any one of claims 1 to 5, characterized in that: The battery management system further comprises: A pre-discharge switch and a resistor, wherein the pre-discharge switch and the resistor are connected in series and then connected in parallel with the discharge switch; The integrated circuit is further configured to: Before controlling the discharge switch to be turned on, controlling the pre-discharge switch to be turned on; In response to one or more of the following conditions being met, the discharge switch is first controlled to be turned on, and then the pre-discharge switch is controlled to be turned off: i) the terminal voltage of the main circuit is between a first voltage threshold V1 and a second voltage threshold V2; Where V1=k1×V 满充 , V2=k2×V 满充 , 0<k1<k2, define V 满充 is the full charge voltage of the battery pack; ii) within the fifth time period, the duration for which the discharge current on the pre-discharge switch is less than or equal to the fourth current threshold does not exceed the time period threshold; The fifth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

7. The battery pack according to claim 6, characterized in that: k1∈[0.1,0.7], k2∈[1.0,3.75].

8. The battery pack according to any one of claims 1 to 7, characterized in that: The integrated circuit is further configured to: In response to the battery management system being awakened, the level on the first terminal is not flipped, and the terminal voltage of the main circuit is less than or equal to a third voltage threshold, controlling or keeping the charging switch turned on, and controlling or keeping the discharging switch turned off; The third voltage threshold is defined to be less than or equal to the maximum charging voltage of the battery pack.

9. The battery pack according to claim 8, characterized in that: The integrated circuit is configured to: determine that the battery pack is in a charging state in response to the current measuring unit measuring that a charging current flows through the main circuit; The charging state includes a first charging state; I 充1 ∈[fifth current threshold, sixth current threshold], define I 充1 is the charging current when the battery pack is in the first charging state; Wherein, the fifth current threshold is greater than zero, and the sixth current threshold is ≤ the maximum charging current of the battery pack; The integrated circuit is further configured to: In response to the battery pack being in the first charging state, controlling the discharge switch to open; or, In response to the battery pack being in the first charging state and maintaining the first charging state for a sixth time period, controlling the discharge switch to open.

10. The battery pack according to claim 8 or 9, characterized in that: The integrated circuit is further configured to: In response to the battery pack being in a fully charged state, or in response to the battery pack being in a trickle charge state, or in response to the current of the battery pack being in a current interval and lasting for a seventh time period, controlling the charging switch to be turned off; The current interval is defined as [eighth current threshold, ninth current threshold], the eighth current threshold ∈ [-100mA, 0], and the ninth current threshold ∈ (0mA, 600mA]; The trickle charging state is defined as follows: the charging current ∈ [0.05C, 0.1C] of the battery pack.

11. The battery pack according to any one of claims 1 to 10, characterized in that: The first terminal is configured to wake up the battery management system in response to a level on the first terminal being flipped; and / or, The connector further includes a positive terminal and a negative terminal, wherein the positive terminal and the negative terminal are configured to wake up the battery management system in response to a change in a voltage signal between the positive terminal and the negative terminal; and / or, The current measurement unit is further configured to wake up the battery management system in response to a change in the current signal on the main circuit; and / or, The battery management system further comprises: a voltage detection circuit electrically connected to the integrated circuit, the voltage detection circuit electrically connected to the positive terminal and / or the negative terminal; The voltage detection circuit is configured to wake up the battery management system in response to a change in the voltage of the positive terminal and / or the negative terminal.

12. A battery pack management method, characterized in that: Applicable to a battery pack according to any one of claims 1 to 12; the method comprising: In response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; In response to the terminal voltage of the main circuit being greater than or equal to the voltage of the battery pack, controlling or keeping the discharge switch open, and controlling or keeping the charge switch closed; and / or, In response to the battery management system being awakened, the level on the first terminal is flipped, and it is determined that the battery pack is in a discharging state; In response to the terminal voltage of the main circuit being less than or equal to the voltage of the battery pack, and the fluctuation value of the terminal voltage of the main circuit being within a first range and lasting for a first time period, the discharge switch is controlled or kept open, and the charge switch is controlled or kept closed.

13. The method according to claim 12, characterized in that The discharge state includes a first discharge state; I 放1 is less than or equal to the first current threshold, defined as I 放1 is the discharge current of the battery pack when it is in the first discharge state; Wherein, the first current threshold is less than zero; The method further comprises: In response to the battery pack being in the first discharge state, keeping the discharge switch turned on and controlling the charge switch to turn on; or, In response to the battery pack being in the first discharge state and maintaining the first discharge state for a second time period, the discharge switch is kept turned on and the charge switch is controlled to be turned on.

14. The method according to claim 12 or 13, characterized in that The discharge state also includes a second discharge state; I 放2 ∈[second current threshold, third current threshold], define I 放2 is the discharge current of the battery pack when it is in the second discharge state; Wherein, the second current threshold is less than zero, and the third current threshold is ≤100mA; The method further comprises: In response to the battery pack being in the second discharge state, keeping the discharge switch open, and controlling or keeping the charge switch closed; or, In response to the battery pack being in the second discharge state and maintaining the state for a third time period, the discharge switch is kept open, and the charge switch is controlled or kept closed.

15. The method according to claim 13, characterized in that The method further comprises: In response to the current on the main circuit being greater than the maximum charging current of the battery pack and being maintained for a fourth time period, the charging switch is controlled to be turned off.

16. The method according to claim 12 or 13, characterized in that The discharge state also includes a third discharge state; The third discharge state is defined as follows: the electric energy discharged by the battery pack is greater than or equal to the sum of the electric energy required by other battery packs and the electric device; The method further comprises: In response to the battery pack being in the third discharge state, the discharge switch is controlled to be turned off, and the charge switch is controlled to be turned off.

17. The method according to any one of claims 12 to 16, characterized in that: The battery management system further comprises: A pre-discharge switch and a resistor, wherein the pre-discharge switch and the resistor are connected in series and then connected in parallel with the discharge switch; Before controlling the discharge switch to open, the method further includes: Controlling the pre-discharge switch to open; In response to one or more of the following conditions being met, the discharge switch is first controlled to be turned on, and then the pre-discharge switch is controlled to be turned off: i) the terminal voltage of the main circuit is between a first voltage threshold V1 and a second voltage threshold V2; Where V1=k1×V 满充 , V2=k2×V 满充 , 0<k1<k2, define V 满充 is the full charge voltage of the battery pack; ii) within the fifth time period, the duration for which the discharge current on the pre-discharge switch is less than or equal to the fourth current threshold does not exceed the time period threshold; The fifth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

18. The method according to claim 17, characterized in that k1∈[0.1,0.7], k2∈[1.0,3.75].

19. The method according to any one of claims 12 to 18, characterized in that: The method further comprises: In response to the battery management system being awakened, the level on the first terminal is not flipped, and the terminal voltage of the main circuit is less than or equal to a third voltage threshold, controlling or keeping the charging switch turned on, and controlling or keeping the discharging switch turned off; The third voltage threshold is defined to be less than or equal to the maximum allowable charging voltage of the battery pack.

20. The method according to claim 19, characterized in that The method further includes: in response to the current measuring unit measuring that a charging current flows through the main circuit, determining that the battery pack is in a charging state; The charging state includes a first charging state; I 充1 ∈[fifth current threshold, sixth current threshold], define I 充1 is the charging current when the battery pack is in the first charging state; Wherein, the fifth current threshold is greater than zero, and the sixth current threshold is ≤ the maximum charging current of the battery pack; The method further comprises: In response to the battery pack being in the first charging state, controlling the discharge switch to open; or, In response to the battery pack being in the first charging state and maintaining the first charging state for a sixth time period, the discharge switch is controlled to be opened.

21. The method according to claim 19 or 20, characterized in that The method further comprises: In response to the battery pack being in a fully charged state, or in response to the battery pack being in a trickle charge state, or in response to the current of the battery pack being in a current interval and lasting for a seventh time period, controlling the charging switch to be turned off; The current interval is defined as [eighth current threshold, ninth current threshold], the eighth current threshold ∈ [-100mA, 0], and the ninth current threshold ∈ (0mA, 600mA]; The trickle charging state is defined as follows: the charging current ∈ [0.05C, 0.1C] of the battery pack.

22. A battery management system, characterized in that: It comprises an integrated circuit and a memory, wherein the memory is used to store instructions, and the integrated circuit is used to execute the instructions to implement the battery pack management method according to any one of claims 12 to 21.

23. An electrical equipment, characterized in that: Comprising a battery pack as described in any one of claims 1 to 12 or a battery management system as described in claim 22.

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