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

Abstract

The battery pack comprises a connector and a battery management system electrically connected with the connector, the connector includes a communication terminal configured to communicate with an external device; the battery management system comprises a current measuring unit arranged on the main circuit, a charging switch and a discharging switch arranged 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 further configured to respond to the situation that the battery management system is awakened, the integrated circuit receives a first signal sent by the electric equipment, and the integrated circuit determines that the battery pack is in a discharging state and controls or keeps the discharging switch to be turned on and controls or keeps the charging switch to be turned off in response to the situation that the battery management system is awakened; and / or, in response to the situation that the battery management system is awakened, the integrated circuit receives a second signal sent by the charging equipment, and the integrated circuit determines that the battery pack is in a charging state and controls or keeps the charging switch to be turned on and controls or keeps the discharging switch to be turned 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. If the circulating current is too large, it is easy to cause the battery pack to be protected by current limiting, 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, so that the risk of circulating current can be reduced.

[0006] In a first aspect, an embodiment of the present application provides a battery pack, including a connector and a battery management system electrically connected to the connector; the connector includes a communication terminal, and the communication terminal is configured to communicate with an external device; 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 integrated circuit receives a first signal sent by the power-consuming device, the integrated circuit determines that the battery pack is in a discharging state, and controls or keeps the discharging switch on, and controls or keeps the charging switch off; and / or, in response to the battery management system being awakened, the integrated circuit receives a second signal sent by the charging device, the integrated circuit determines that the battery pack is in a charging state, and controls or keeps the charging switch on, and controls or keeps the discharging switch off.

[0007] In the above embodiment, when the battery pack is in the discharging state, the discharge switch is in the closed state, so that the battery pack can be prepared for discharge in advance and the battery capacity and power can be expanded; the charging switch is in the disconnected state, so that the battery pack cannot be charged by other parallel battery packs, reducing the risk of circulating current. When the battery pack is in the charging state, the discharge switch is in the disconnected state, so that the battery pack cannot discharge to other parallel battery packs, reducing the risk of circulating current in the battery pack. In addition, the charging switch is in the open state, which does not affect the charging of the battery pack, thereby improving the parallel charging efficiency. In addition, based on the communication signal received by the communication terminal to wake up the battery management system and determine the status of the battery pack, fewer hardware interface requirements are required, 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 first duration, 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. 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 charge switch off; or, in response to the battery pack being in the second discharge state and maintaining the second time length, the integrated circuit keeps the discharge switch open and controls or keeps the charge switch off.

[0010] 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.

[0011] In one or more embodiments, the integrated circuit is further configured to: in response to the current on the main circuit being greater than the maximum charging current of the battery pack, control the charging switch to turn off; or, in response to the current on the main circuit being greater than the maximum charging current of the battery pack and maintaining the third time period, control the charging switch to turn off. If the current on the main circuit is greater than the maximum charging current of the battery pack, the battery pack may have a circulating current or feedback, and the charging current of the battery pack is relatively large, the charging switch of the battery pack is controlled to turn off, thereby reducing the risk of a large current on the main circuit impacting the charging and discharging switch and the battery, and reducing safety hazards.

[0012] 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: in response to the battery pack being in a discharge state, before controlling the discharge switch to be turned on, control the pre-discharge switch to be turned on; in response to one or more of the following conditions being met, control the discharge switch to be turned on first, and then control the pre-discharge switch to be turned off:

[0013] i) the terminal voltage of the main circuit is between a first voltage threshold V1 and a second voltage threshold V2;

[0014] 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;

[0015] ii) within the fourth 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;

[0016] The fourth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

[0017] 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.

[0018] 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.

[0019] In one or more embodiments, the integrated circuit is further configured to: in response to the battery pack being in a charging state and the charging current of the battery pack being less than or equal to the maximum charging current of the battery pack, 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.

[0020] In one or more embodiments, in response to the current on the main circuit being greater than the maximum charging current of the battery pack, the charging switch is controlled to be turned off; or, in response to the current on the main circuit being greater than the maximum charging current of the battery pack and lasting for a fifth period of time, the charging switch is controlled to be turned off.

[0021] The integrated circuit detects that the current in the main circuit is greater than the maximum charging current of the battery pack, or the current in the main circuit is greater than the maximum charging current of the battery pack and lasts for the fifth period of time. The battery pack may have circulating current or charging abuse, and the charging current of the battery pack is large. The charging switch of the battery pack is controlled to be turned off, reducing the risk of large current in the main circuit impacting the charging and discharging switches and batteries, thereby reducing safety hazards.

[0022] 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: in response to the battery management system being awakened and the battery pack not receiving the first signal sent by the power-consuming device and the second signal sent by the charging device, control the pre-discharge switch to open.

[0023] When the state of the battery pack cannot be determined, the pre-discharge switch is controlled to open so that the discharge path of the main circuit is turned on, and the battery pack is prepared for discharge in advance, so that the integrated circuit can determine the state of the battery pack based on the current in the main circuit. For example, when the integrated circuit detects that the current in the main circuit is less than zero, it determines that the battery pack is in a discharging state, first controls the discharge switch to open, and then controls the pre-discharge switch to turn off, and then determines whether the battery pack is in the first discharge state or the second discharge state in the aforementioned embodiment, controls the charging switch to open or turn off, and expands the battery capacity and power in time.

[0024] In one or more embodiments, in response to the communication terminal receiving the communication signal, the battery management system is awakened.

[0025] In one or more embodiments, the connector further comprises a positive terminal and a negative terminal; in response to a voltage change between the positive terminal and the negative terminal, the battery management system is awakened.

[0026] In one or more embodiments, the battery management system is awakened in response to a change in current on the main circuit.

[0027] 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.

[0028] In one or more embodiments, the battery pack also includes a voltage detection circuit electrically connected to the integrated circuit, the connector also includes a positive terminal and a negative terminal, and the voltage detection circuit is electrically connected to the positive terminal and / or the negative terminal; in response to changes in the voltage on the positive terminal and / or the negative terminal, the battery management system is awakened.

[0029] 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 of the present application.

[0030] The management method includes: in response to the battery management system being awakened, the integrated circuit receives a first signal sent by the power-consuming device, the integrated circuit determines that the battery pack is in a discharging state, and controls or keeps the discharging switch open, and controls or keeps the charging switch off; and / or, in response to the battery management system being awakened, the integrated circuit receives a second signal sent by the charging device, the integrated circuit determines that the battery pack is in a charging state, and controls or keeps the charging switch open, and controls or keeps the discharging switch off.

[0031] 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 management method further includes: 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 first time length, the integrated circuit keeps the discharge switch turned on and controls the charge switch to turn on.

[0032] 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2is 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 management method further includes: in response to the battery pack being in the second discharge state, the integrated circuit keeps the discharge switch turned on and controls or keeps the charge switch turned off; or, in response to the battery pack being in the second discharge state and maintaining the second time length, the integrated circuit keeps the discharge switch turned on and controls or keeps the charge switch turned off.

[0033] In one or more embodiments, the management method further includes: in response to the current on the main circuit being greater than the maximum charging current of the battery pack, controlling the charging switch to turn off; or, in response to the current on the main circuit being greater than the maximum charging current of the battery pack and maintaining it for a third time period, controlling the charging switch to turn off.

[0034] In one or more embodiments, the battery management system further includes: 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.

[0035] The management method further includes: in response to the battery pack being in a discharging state, 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, first controlling the discharge switch to be turned on, and then controlling the pre-discharge switch to be turned off:

[0036] i) the terminal voltage of the main circuit is between a first voltage threshold V1 and a second voltage threshold V2;

[0037] 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;

[0038] ii) within the fourth 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;

[0039] The fourth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

[0040] In one or more embodiments, k1∈[0.1,0.7], k2∈[1.0,3.75].

[0041] In one or more embodiments, the management method further includes: in response to the battery pack being in a charging state and the charging current of the battery pack being less than or equal to the maximum charging current of the battery pack, controlling the discharge switch to open.

[0042] In one or more embodiments, the management method also includes: in response to the current in the main circuit being greater than the maximum charging current of the battery pack, controlling the charging switch to turn off; or, in response to the current in the main circuit being greater than the maximum charging current of the battery pack and lasting for a fifth period of time, controlling the charging switch to turn off.

[0043] In one or more embodiments, the pre-discharge switch and the resistor are connected in series and then connected in parallel with the discharge switch. The management method also includes: in response to the battery management system being awakened and the battery pack not receiving the first signal sent by the power-consuming device and the second signal sent by the charging device, controlling the pre-discharge switch to open.

[0044] 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.

[0045] 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.

[0046] 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

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

[0048] Figure 1 This is a schematic diagram of the structure of a battery pack in some embodiments of the present application;

[0049] Figure 2 A schematic diagram of two battery packs being discharged in parallel in some embodiments of the present application;

[0050] Figure 3 A schematic diagram of a control scheme of an integrated circuit in some embodiments of the present application;

[0051] Figure 4 This is a control schematic diagram of a battery pack in a discharge state in some embodiments of the present application;

[0052] Figure 5 This is a control schematic diagram of a battery pack in a discharge state in some embodiments of the present application;

[0053] Figure 6This is a control schematic diagram of a battery pack in a first discharge state in some embodiments of the present application;

[0054] Figure 7 This is a control schematic diagram of a battery pack in a second discharge state in some embodiments of the present application;

[0055] Figure 8 This is a control schematic diagram of a battery pack in a certain state in some embodiments of the present application;

[0056] Fig. 9 A schematic diagram of a circuit for discharging two battery packs in parallel in some embodiments of the present application;

[0057] Fig.10 This is a control schematic diagram of a battery pack in a charging state in some embodiments of the present application;

[0058] Fig.11 This is a control schematic diagram of a battery pack in a normal charging state in some embodiments of the present application;

[0059] Fig.12 This is a control schematic diagram of a battery pack in a certain state in some embodiments of the present application;

[0060] Fig.13 This is a schematic diagram of the structure of a battery pack in some embodiments of the present application;

[0061] Fig.14A and Fig. 14B This is a flowchart of a battery pack management method in some embodiments of the present application. DETAILED DESCRIPTION

[0062] 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.

[0063] 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.

[0064] 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.

[0065] In the related art, during the parallel connection of battery packs, multiple signal terminals are set on the connector of the battery pack. For example, the charging detection signal terminal is used to detect whether the battery pack is connected to a charging device, and the power-consuming device enable signal terminal is used to detect whether the battery pack is connected to a power-consuming device. When a signal interface fails, the battery pack cannot accurately determine its own status and cannot reliably manage the parallel connection of the battery pack to control the circulation risk.

[0066] To this end, the embodiments of the present application provide a battery pack and management method thereof, a battery management system and an electrical device to reduce the risk of circulating current. 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.

[0067] Battery Pack

[0068] 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).

[0069] 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. 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.

[0070] The connector 10 also includes a communication terminal 13, which is a terminal for transmitting communication signals, and the communication terminal 13 is communicatively connected to the BMS30. When the connector 10 is connected to an electrical device (not shown), the BMS30 is communicatively connected to the electrical device through the communication terminal 13. In this embodiment, the communication terminal 13 is used to transmit communication signals for interaction between the BMS30 and the electrical device. When the connector 10 is connected to a charging device (not shown), the BMS30 is communicatively connected to the charging device through the communication terminal 13. In this embodiment, the communication terminal 13 is used to transmit communication signals for interaction between the BMS30 and the charging device.

[0071] In some embodiments, the communication terminal 13 is also used for transmitting signals of multiple battery packs. For example, when multiple battery packs are connected in parallel, the signals of the battery packs are transmitted through the communication terminal 13, the communication circuit provided on the BMS 30, and the communication signal line.

[0072] 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-.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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, voltage and temperature of the battery cell.

[0078] 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.

[0079] 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 .

[0080] 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.

[0081] In some embodiments, the integrated circuit 34 includes a MCU 341 (Micro Controller Unit, MCU) and an AFE 342 connected to the MCU 341 .

[0082] 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.

[0083] 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.

[0084] 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.

[0085] In some other 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.

[0086] 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.

[0087] It is understandable that MCU341 also includes input / output ports, timers, analog-to-digital converters (ADCs) or digital-to-analog converters (DACs), etc.

[0088] 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.

[0089] 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.

[0090] The integrated circuit 34 controls the switch on the main circuit to open or close, and establish or cut off the electrical connection between the battery pack 100 and the external device. The external device includes a charging device or an 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 external 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] In some embodiments of the present application, the connector of the battery pack only includes a positive terminal, a negative terminal and a communication terminal, and does not include other signal terminals, such as a charging detection signal terminal, an enable (ON) terminal, etc., or the connector includes a charging detection signal terminal and an enable (ON) terminal, but the battery management system is not provided with a communication circuit and an enable circuit corresponding to the charging detection signal terminal and the enable (ON) terminal, and is unable to monitor whether the battery pack is connected to an external device. From another perspective, these terminals are regarded as "fake terminals".

[0095] In some embodiments, when the connector is connected to an electric device, the communication terminal receives a communication signal sent by the electric device to wake up the BMS. In some embodiments, when the connector is connected to a charging device, the communication terminal receives a communication signal sent by the charging device to wake up the BMS. In other embodiments, the wake-up of the BMS includes other methods, which will be introduced below. This application does not limit the wake-up method of the BMS.

[0096] When the battery pack is connected to an electric device, the communication terminal receives a first signal sent by the electric device and transmits the first signal to the BMS. After receiving the first signal, the integrated circuit in the BMS determines that the battery pack is in a discharging state.

[0097] Taking the electric equipment as the whole vehicle load as an example, in some embodiments, the whole vehicle load and the battery pack BMS use the CAN protocol to communicate, and the first signal is the CAN message sent by the whole vehicle load based on the whole vehicle protocol. The CAN message includes the battery pack ID (Identity Document) and the vehicle load ID. The BMS obtains the battery pack ID and the vehicle load ID in the CAN message, verifies that the battery pack ID recorded in the CAN message is the ID of the battery pack to which it belongs, identifies the vehicle load ID, and determines that the battery pack is connected to the vehicle load, indicating that the battery pack has the discharge condition, and then determines that the battery pack is in the discharge state.

[0098] In some embodiments, the vehicle load and the battery pack BMS communicate using the UART protocol, and the first signal is a UART data frame sent by the vehicle load based on the vehicle protocol, and the UART data frame includes the protocol device address of the battery pack and the protocol device address of the vehicle load. The BMS obtains the protocol device address of the battery pack and the protocol device address of the vehicle load in the UART data frame, verifies that the protocol device address in the UART data frame is the protocol device address of the battery pack in which it is located, identifies the protocol address of the vehicle load, and determines that the battery pack is connected to the vehicle load, indicating that the battery pack has discharge conditions, and then determines that the battery pack is in a discharge state.

[0099] See also Figure 3 After the integrated circuit determines that the battery pack is in a discharging state, it controls or keeps the discharge switch open and controls or keeps the charge switch off. In this way, the discharge switch is in a closed state, so that the battery pack can be prepared for discharge in advance, expanding the battery capacity and power; the charge switch is in an open state, so that the battery pack cannot be charged by other parallel battery packs, reducing the risk of circulating current.

[0100] Taking into account 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 parallel process. In one or more embodiments, the integrated circuit controls the opening or closing of the discharge switch and the charging switch in combination with the terminal voltage of the main circuit.

[0101] In some embodiments, after determining that the battery pack is in a discharging state, the integrated circuit monitors that 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.

[0102] Combination Figure 2 For example, the integrated circuit of battery pack 1# receives the first signal sent by the vehicle load 200, determines that battery pack 1# is connected to the power-consuming device, and that battery pack 1# is in a discharging state, and monitors the terminal voltage V 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 1# controls or keeps the discharge switch 33 of the battery pack 1# open, and controls or keeps the charge switch 32 closed.

[0103] The terminal voltage of the main circuit V p / c Greater 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#.

[0104] 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 the 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.

[0105] In some embodiments, after determining that the battery pack is in a discharging state, the integrated circuit monitors that 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 period of time t, controls or keeps the discharge switch open, and controls or keeps the charging switch off.

[0106] The terminal voltage of the main circuit is less than or equal to the voltage of the battery pack, which may be: there are no other battery packs connected in parallel with this battery pack, or there are other battery packs connected in parallel with this battery pack, and the voltage of this battery pack is greater than that of other battery packs, etc. Further, after determining that the fluctuation value of the terminal voltage of the main circuit is within the first range and lasts for a period of time t, it means that the terminal voltage of the main circuit is stable, and 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 this battery pack is controlled or kept open, and this battery pack will not charge other battery packs connected in parallel, thereby reducing the risk of circulating current.

[0107] 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 duration t is 1s, 2s, 3s or 5s, etc.

[0108] Combination Figure 2 For example, when the integrated circuit of battery pack 1# receives the first signal sent by the vehicle load 200, it is determined that the battery pack 1# is connected to the power-consuming device and the battery pack 1# is in a discharging state, and 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.

[0109] 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 Vp / c The fluctuation value of is within the first range and lasts for a period of time t, 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.

[0110] In the above embodiment, the battery management system monitors the terminal voltage of the main circuit and the voltage of the battery pack, and 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 closed. 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.

[0111] It is understandable that when the battery pack leaves the factory, the states of the discharge switch and the charge switch have default settings.

[0112] In some embodiments, for a battery pack with a blind discharge setting, when the battery pack leaves the factory, the discharge switch is turned on and the charge switch is turned off by default. After determining that the battery pack is in a discharge state, the integrated circuit keeps the discharge switch on and the charge switch off.

[0113] In some embodiments, for a battery pack with blind discharge and blind charge settings, when the battery pack leaves the factory, the discharge switch and the charge switch are both turned on by default. After the integrated circuit determines that the battery pack is in a discharge state, the discharge switch is kept turned on and the charge switch is controlled to be turned off.

[0114] In some embodiments, when the battery pack leaves the factory, the discharge switch and the charging switch are both turned off by default. After the integrated circuit detects that the battery pack is in a discharging state, it controls the discharge switch to be turned on and keeps the charging switch off. In some embodiments, when the battery pack leaves the factory, the discharge switch is turned off and the charging switch is turned on by default. After the integrated circuit detects that the battery pack is in a discharging state, it controls the discharge switch to be turned on and the charging switch to be turned off.

[0115] It can be seen that the solution of the integrated circuit controlling the charging switch and the discharging switch in the present application is applicable to battery packs with various default settings and has a wide range of applications.

[0116] 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. Based on the current of the battery pack, the integrated circuit further determines the state of the battery pack and controls the discharge switch and / or the charging switch to reduce the risk of circulating current.

[0117] 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.

[0118] 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).

[0119] 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.

[0120] 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.

[0121] 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 first time length. That is, the integrated circuit detects that the battery pack is in the first discharge state and maintains the first time length, and the battery pack normally supplies power to the first load with large power consumption. Among them, setting the first time length is conducive to reducing misjudgment. The first time length is specifically set based on the battery pack or the power-consuming device. Exemplarily, the first time length is 1s or 2s, etc.

[0122] 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.

[0123] 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.

[0124] 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].

[0125] 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 and a state where the battery pack is not discharged at all.

[0126] 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 aforementioned embodiments.

[0127] 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 low power consumption, such as the instrument panel on the electric two-wheeled vehicle, the discharge current value is small, for example, 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 low power consumption on the electric vehicle, such as the central control system, air conditioning, audio or electric windows, the discharge current value is small, for example, about close to -1A, and the second current threshold value is determined to be -1A, -1.5A or -2A.

[0128] 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.

[0129] 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 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 100mA, it is determined that the charging current is flowing through the main circuit. When the current of the battery pack is between ±100mA, it is determined that no current is flowing through the main circuit.

[0130] 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.

[0131] 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 the second time length. Among them, setting the second time length is conducive to reducing misjudgment, and the second time length is specifically set based on the battery pack or the electrical device. For example, the second time length is 1s or 2s.

[0132] 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).

[0133] 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 second 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.

[0134] 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 7 As shown, in the present application, it is found that the battery pack 1# is in the second discharge state or in the second discharge state and maintained for the second time, and the charging switch 32 of the battery pack is controlled or kept turned off, so as to reduce the risk of circulating current caused by 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.

[0135] 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.

[0136] In other scenarios, when the driver finds that the power of a battery pack is too low while the electric vehicle is driving, he may stop the electric vehicle and 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 is also charged.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] Based on the above considerations, in some embodiments, from the perspective of current, if the current on the main circuit is greater than the maximum charging current of the battery pack, the charging switch is controlled to be turned off. 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.

[0142] In some embodiments, from the perspective of electric energy, monitor whether the electric energy provided by the feedback current or circulating current to the battery pack exceeds the battery pack's tolerance. Set a third duration, the integrated circuit detects that the current on the main circuit is greater than the maximum charging current of the battery pack, and maintains the third duration to control the charging switch to turn off. The third duration is related to the magnitude of the maximum charging current. Setting the third duration and monitoring from the perspective of electric energy is beneficial to the accuracy of monitoring.

[0143] See also Figure 8 , 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 a third period of time, 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.

[0144] In some embodiments, see Fig. 9 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 .

[0145] 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.

[0146] 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.

[0147] 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. On the one hand, the terminal voltage of the main circuit is 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:

[0148] i) Terminal voltage V of the main circuit p / c between a first voltage threshold V1 and a second voltage threshold V2;

[0149] 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;

[0150] ii) within the fourth 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;

[0151] The fourth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

[0152] 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, indicating that the terminal voltage of the battery pack is within the tolerance range of the battery pack, such as within the tolerance range of the battery module, switch, and some other electronic devices.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] For the above condition ii), within the fourth 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 fourth 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.

[0157] 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 within a safe range and no short circuit occurs outside the battery pack. The discharge switch is then controlled to open, making the battery pack discharge safer.

[0158] It can be seen from the above embodiments that the integrated circuit responds to the battery management system being awakened and receiving the first signal sent by the power-consuming device, determines that the battery pack is in a discharging state, and controls the pre-discharge switch to open; after monitoring that at least one of the above conditions i) and ii) is met, first controls the discharge switch to open, and then controls the pre-discharge switch to turn off, 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, allowing the battery pack to continue to discharge to the outside, and avoiding power jams in the load.

[0159] In some other embodiments, the integrated circuit controls the pre-discharge switch to open in response to the battery management system being awakened and the battery pack not receiving the first signal sent by the power-consuming device and the second signal sent by the charging device.

[0160] In the above embodiment, the battery management system is awakened in response to a change in the voltage between the positive terminal and the negative terminal, or the battery management system is awakened in response to a change in the voltage on the positive terminal and / or the negative terminal. The above awakening method will be described below and will not be described in detail here.

[0161] If the battery pack does not receive the first signal sent by the power-consuming device and the second signal sent by the charging device, the state of the battery pack cannot be determined. When the state of the battery pack cannot be determined, the pre-discharge switch is controlled to open so that the discharge path of the main circuit is turned on. Based on the current limiting effect of the resistor, the current in the main circuit is within a safe range. In this way, the battery pack is prepared for discharge in advance, and it does not affect the subsequent determination of the state of the battery pack based on the first signal or the second signal by the integrated circuit for subsequent control.

[0162] For example, the integrated circuit receives a first signal sent by an electric device, determines that the battery pack is in a discharging state, and after monitoring that at least one of the above conditions i) and ii) is met, first controls the discharge switch to be turned on, and then controls the pre-discharge switch to be turned off. For another example, the integrated circuit receives a second signal sent by a charging device, determines that the battery pack is in a charging state, first controls the pre-discharge switch to be turned off, and then controls the charging switch to be turned on, and keeps the discharge switch turned off.

[0163] In addition, when the state of the battery pack cannot be determined, the pre-discharge switch is controlled to open so that the discharge path of the main circuit is turned on, which facilitates the integrated circuit to determine the state of the battery pack based on the current on the main circuit. For example, when the integrated circuit detects that the current on the main circuit is less than zero, it determines that the battery pack is in a discharging state, first controls the discharge switch to open, and then controls the pre-discharge switch to turn off, and then determines whether the battery pack is in the first discharge state or the second discharge state in the aforementioned embodiment, controls the charging switch to open or turn off, and expands the battery capacity and power in time.

[0164] In some scenarios, battery pack 1# and battery pack 2# are charged in parallel by a charging device. When the battery pack is connected to the charging device, the communication terminal receives a second signal sent by the charging device and transmits the second signal to the BMS. After the integrated circuit in the BMS receives the second signal, it determines that the battery pack is in a charging state.

[0165] The charging device is a charging pile, a charger or a charging gun. Taking the charging device as a charging pile as an example, in some embodiments, the charging pile and the battery pack BMS communicate using the CAN protocol, and the second signal is a CAN message sent by the charging pile based on the charging protocol. The CAN message includes the battery pack ID (Identity Document) and the charging pile ID. The BMS obtains the battery pack ID and the charging pile ID in the CAN message, verifies that the battery pack ID recorded in the CAN message is the ID of the battery pack to which it belongs, identifies the charging pile ID, and determines that the battery pack is connected to the charging pile, indicating that the battery pack has charging conditions, and then determines that the battery pack is in a charging state.

[0166] In some embodiments, the charging pile and the battery pack BMS communicate using the UART protocol, and the first signal is a UART data frame sent by the charging pile based on the charging protocol, and the UART data frame includes the protocol device address of the battery pack and the protocol device address of the charging pile. The BMS obtains the protocol device address of the battery pack and the protocol device address of the charging pile in the UART data frame, verifies that the protocol device address in the UART data frame is the protocol device address of the battery pack in which it is located, identifies the protocol device address of the charging pile, and determines that the battery pack is connected to the charging pile, indicating that the battery pack has charging conditions, and then determines that the battery pack is in a charging state.

[0167] Please refer again Figure 3The integrated circuit receives the second signal sent by the charging device, determines that the battery pack is in a charging state, and then controls or keeps the charging switch turned on and controls or keeps the discharging switch turned off.

[0168] When the integrated circuit of battery pack 1# receives the second signal sent by the charging device, the integrated circuit determines that battery pack 1# is in a charging state. Fig.10 As shown, 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.

[0169] After the above control is completed, the charging path on the main circuit is turned on, and the current measurement unit measures the charging current on the main circuit. The integrated circuit further controls the charging switch and / or the discharging switch based on the charging current to improve charging safety.

[0170] In some embodiments, the battery pack is in a charging state, and the integrated circuit detects that the charging current of the battery pack is less than or equal to the maximum charging current of the battery pack, and controls the discharge switch to open.

[0171] The maximum charge current refers to the maximum continuous current allowed when charging the battery pack. The maximum charge current can be obtained from the battery pack label, battery module label, packaging, user manual, instructions, advertising, marketing or other supporting documents.

[0172] The charging current of the battery pack is less than or equal to its maximum charging current, indicating that the battery pack is in a normal charging state.

[0173] See also Fig.11 When the battery pack 1# is charged normally, the charging switch 32 is kept open and the discharging switch 33 is controlled to be 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.

[0174] In some scenarios, the aging conditions of each battery pack are different, and multiple battery packs connected in parallel have different internal resistances or temperatures during the charging process. Each battery pack receives a different charging current, and some battery packs may receive a charging current greater than they can withstand.

[0175] In other scenarios, the battery pack is charged by a charger that does not match the battery pack, that is, the battery pack is abused by charging, which may cause the charging current of the battery pack to be greater than the charging current it can withstand.

[0176] In some embodiments of the present application, a charging current less than or equal to the tolerable charging current of the battery pack is allowed, which is beneficial to improving the charging efficiency. In other embodiments, a charging current greater than the tolerable charging current of the battery pack provides the battery pack with electrical energy within the tolerable capacity of the battery pack in a short period of time.

[0177] In some other embodiments, when the charging current is greater than the tolerable charging current and the electrical energy they provide to the battery pack exceeds the battery pack's tolerance, it causes overheating or polarization of the battery cells, causing damage to the battery pack. This situation is not allowed.

[0178] 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.

[0179] Based on the above considerations, in some embodiments, the integrated circuit detects that the charging current on the main circuit is greater than the maximum charging current of the battery pack, and controls the charging switch to turn off. In some embodiments, the integrated circuit detects that the current on the main circuit is greater than the maximum charging current of the battery pack and lasts for the fifth time period, and controls the charging switch to turn off. The fifth time period is related to the magnitude of the maximum charging current. Setting the fifth time period and monitoring from the perspective of electric energy is conducive to the accuracy of monitoring.

[0180] See also Fig.12 , the integrated circuit of battery pack 1# detects that the current on its main circuit is greater than the maximum charging current of the battery pack, or the current on the main circuit is greater than the maximum charging current of the battery pack and lasts for the fifth period of time, battery pack 1# may have overcharging or charging abuse, 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 battery pack 1#, reducing the risk of large current in the main circuit impacting the charging and discharging switches and batteries, and reducing safety hazards.

[0181] In some embodiments, the communication terminal is configured to wake up the battery management system in response to the communication terminal receiving a communication signal. For example, after the battery pack is connected to a charging device, the communication terminal receives a second signal sent by the charging device, thereby waking up the battery management system and further determining that the battery pack is in a charging state.

[0182] 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.

[0183] 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.

[0184] 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 or the pre-discharge switch is turned on by default. When the battery pack is connected to an electrical device or a charging 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.

[0185] 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.

[0186] 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.

[0187] like Fig.13 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.

[0188] 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.

[0189] 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 connection, a communication terminal is retained on the connector of the battery pack. The battery pack and the power-consuming equipment no longer need to design and layout more communication circuits, reducing the cost of the entire system.

[0190] Battery Pack Management Method

[0191] 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.14A and Fig. 14B , I will not go into details here.

[0192] Battery Management System

[0193] 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.

[0194] 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.

[0195] Electrical equipment

[0196] 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.

[0197] 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.

[0198] 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 communication terminal configured to communicate with an external device; 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 is configured to control the charging switch and / or the discharging switch; characterized in that: The integrated circuit is configured to: In response to the battery management system being awakened, the integrated circuit receives a first signal sent by the power-consuming device, the integrated circuit determines that the battery pack is in a discharging state, and controls or keeps the discharging switch turned on, and controls or keeps the charging switch turned off; and / or, In response to the battery management system being awakened, the integrated circuit receives a second signal sent by a charging device, the integrated circuit determines that the battery pack is in a charging state, and controls or keeps the charging switch turned on, and controls or keeps the discharging switch turned off.

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 first 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 second 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 further configured to: In response to the current in the main circuit being greater than the maximum charging current of the battery pack, controlling the charging switch to turn off; or, 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 third period of time, the charging switch is controlled to be turned off.

5. The battery pack according to any one of claims 1 to 4, 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: In response to the battery pack being in a discharging state, before controlling the discharging switch to be turned on, controlling the pre-discharging 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 fourth 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 fourth duration is greater than the duration threshold, and the fourth current threshold is a negative value.

6. The battery pack according to claim 5, characterized in that: k1∈[0.1,0.7], k2∈[1.0,3.75].

7. The battery pack according to any one of claims 1 to 6, characterized in that: The integrated circuit is further configured to: In response to the battery pack being in the charging state and the charging current of the battery pack being less than or equal to the maximum charging current of the battery pack, the discharge switch is controlled to be opened.

8. The battery pack according to claim 7, characterized in that: In response to the current in the main circuit being greater than the maximum charging current of the battery pack, controlling the charging switch to turn off; or, In response to the current in the main circuit being greater than the maximum charging current of the battery pack and lasting for a fifth period of time, the charging switch is controlled to be turned off.

9. The battery pack according to any one of claims 1 to 8, 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: in response to the battery management system being awakened and the battery pack not receiving the first signal sent by the power-consuming device and the second signal sent by the charging device, control the pre-discharge switch to open.

10. The battery pack according to any one of claims 1 to 9, characterized in that: In response to the communication terminal receiving a communication signal, waking up the battery management system; and / or, The connector also includes a positive terminal and a negative terminal; waking up the battery management system in response to a change in voltage between the positive terminal and the negative terminal; and / or, In response to a change in current on the main circuit, waking up the battery management system; and / or, The battery pack further comprises a voltage detection circuit electrically connected to the integrated circuit, the connector further comprises a positive terminal and a negative terminal, the voltage detection circuit is electrically connected to the positive terminal and / or the negative terminal; In response to a change in voltage on the positive terminal and / or the negative terminal, the battery management system is awakened.

11. A battery pack management method, characterized in that: Applicable to a battery pack as claimed in any one of claims 1 to 9; The method comprises: In response to the battery management system being awakened, the integrated circuit receives a first signal sent by the power-consuming device, the integrated circuit determines that the battery pack is in a discharging state, and controls or keeps the discharging switch turned on, and controls or keeps the charging switch turned off; and / or, In response to the battery management system being awakened, the integrated circuit receives a second signal sent by a charging device, the integrated circuit determines that the battery pack is in a charging state, and controls or keeps the charging switch turned on, and controls or keeps the discharging switch turned off.

12. The method according to claim 11, 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 comprises: 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 first time period, the integrated circuit keeps the discharge switch turned on and controls the charge switch to turn on.

13. The method according to claim 11 or 12, 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 comprises: 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 second time period, the integrated circuit keeps the discharge switch open, and controls or keeps the charge switch closed.

14. The method according to claim 12, characterized in that The method further comprises: In response to the current in the main circuit being greater than the maximum charging current of the battery pack, controlling the charging switch to turn off; or, 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 third period of time, the charging switch is controlled to be turned off.

15. The method according to any one of claims 11 to 14, 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 method further comprises: In response to the battery pack being in a discharging state, before controlling the discharging switch to be turned on, controlling the pre-discharging 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 fourth time period, the duration for which the discharge current on the pre-discharge switch is less than or equal to the fifth current threshold does not exceed the time period threshold; The fourth duration is greater than the duration threshold, and the fifth current threshold is a negative value.

16. The method according to claim 15, characterized in that k1∈[0.1,0.7], k2∈[1.0,3.75].

17. The method according to any one of claims 11 to 16, characterized in that The method further comprises: In response to the battery pack being in the charging state and the charging current of the battery pack being less than or equal to the maximum charging current of the battery pack, the discharge switch is controlled to be opened.

18. The method according to claim 17, characterized in that The method further comprises: In response to the current in the main circuit being greater than the maximum charging current of the battery pack, controlling the charging switch to turn off; or, In response to the current in the main circuit being greater than the maximum charging current of the battery pack and lasting for a fifth period of time, the charging switch is controlled to be turned off.

19. The method according to any one of claims 11 to 18, 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 method further comprises: In response to the battery management system being awakened and not receiving the first signal sent by the power-consuming device and the second signal sent by the charging device, the pre-discharge switch is controlled to be turned on.

20. 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 11 to 19.

21. An electrical device, characterized in that: Comprising the battery pack according to any one of claims 1 to 10 or the battery management system according to claim 20.

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