Battery charger control method, device and equipment

Abstract

The invention provides a control method, device and equipment of a battery charger, which are used for accurately detecting the connection state of a battery pack. The control method of the battery charger comprises the steps of detecting a charging current of a battery pack when it is determined that the battery charger is started; if the charging current of the battery pack is less than or equal to the first preset current, monitoring the charging voltage of the battery pack; and when determining that the charging voltage of the battery pack meets the preset condition, controlling the battery charger to be turned off. With the adoption of the design, because the proportional-integral control logic is adopted by the conventional battery charger, when the battery pack is disconnected due to a fault, the integrator in the proportional-integral control logic can detect the small change of the charging current when the battery pack is disconnected and can control the battery charger to generate a charging voltage with a relatively large amplitude; when it is detected that the charging current of the battery pack is reduced, the connection state of the battery pack is accurately judged by detecting whether the charging voltage of the battery pack meets the preset condition or not.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a control method, device and equipment for a battery charger. Background Art

[0002] With the continuous development of the Internet and financial industries, the safe and reliable operation of equipment has become increasingly important. As a key power supply device, the uninterruptible power system (UPS) plays an important role.

[0003] When a power grid fails, a UPS can use the energy stored in the battery pack to continue powering the load. Therefore, the proper connection of the battery pack is essential for the UPS to maintain power supply to the load during a power grid failure. Currently, battery pack connection detection primarily detects the charging current output by the battery charger to the battery pack. However, when the battery pack is in a floating charge state, its charging current is close to zero. Therefore, this detection method cannot distinguish between the floating charge state when the battery pack is normally connected and the disconnected state due to a battery fault, which affects the battery pack connection status detection results. Summary of the Invention

[0004] The purpose of this application is to provide a control method, device and equipment for a battery charger, which are used to accurately detect the connection status of a battery pack.

[0005] In a first aspect, the present application provides a method for controlling a battery charger, the method comprising the following steps: detecting the charging current of a battery pack when the battery charger is determined to be on; monitoring the charging voltage of the battery pack if the charging current of the battery pack is less than or equal to a first preset current; and controlling the battery charger to shut down when it is determined that the charging voltage of the battery pack satisfies a preset condition. With the above design, since all battery chargers approved in the industry use proportional-integral control logic, that is, by detecting the charging current of the battery pack, comparing the charging current with a preset value, and controlling the on and off of a switching device within the battery charger based on the error between the actual charging current and the preset value, when the battery pack fails and is disconnected from the battery charger, the integrator in the proportional-integral control logic detects the slight change in the charging current when the battery pack is disconnected and controls the battery charger to generate a larger charging voltage to restore the charging current to the amplitude before the battery pack is disconnected. Therefore, the solution provided by the present application can improve the accuracy of battery pack connection status detection by additionally detecting the charging voltage of the battery pack in addition to detecting the charging current of the battery pack. In addition, the solution provided in this application detects the numerical changes in voltage and current produced during the battery charger's own control process. Compared with the industry's method of actively adjusting the output parameters of the battery charger for detection, it can further reduce the voltage fluctuation value when the battery pack is normally connected, which is beneficial to improving the service life of the battery pack.

[0006] In one possible implementation, the preset condition is that the battery's charging voltage is greater than a first preset voltage, or that the difference in the battery pack's charging voltage within a preset time period is greater than or equal to a first preset threshold. With this design, since the proportional-integral control logic within the battery charger controls the battery charger to generate a charging voltage with a larger amplitude when the battery pack is disconnected due to a fault, the battery pack's connection status can be determined by directly detecting the charging voltage. Furthermore, since the charging current of the battery pack does not increase when the battery pack is disconnected, the proportional-integral control logic controls the battery charger's charging voltage to return to a normal value upon detecting that the battery pack's charging current cannot return to the charging current before the battery pack is disconnected. This means that the battery pack's charging current undergoes a short-term increase. Therefore, detecting the difference in charging voltage within a preset time period can also be used as a criterion for determining the battery pack's connection status.

[0007] In a possible implementation, before determining that the battery charger is turned on, the method further includes: monitoring the voltage of the battery pack, and controlling the battery charger to turn on when it is determined that the voltage of the battery pack is lower than or equal to a second preset voltage.

[0008] In one possible design, the method further includes controlling the battery charger to shut down when it is determined that the difference in the battery pack's charging current within a preset time period is greater than or equal to a second preset threshold. With this design, if the battery pack's charging current rapidly increases or decreases within a short period of time, it indicates a short circuit or other fault in the battery pack or battery charger. To ensure the safety of the battery charger and other devices connected to the battery charger, the battery charger can be controlled to shut down.

[0009] In a second aspect, an embodiment of the present application provides a control device for a battery charger, the device comprising: a detection unit and a control unit.

[0010] Specifically, the control unit is used to control the detection unit to detect the charging current of the battery pack when it is determined that the battery charger is turned on; and to control the detection unit to detect the charging voltage of the battery pack when it is determined that the charging current of the battery pack is less than or equal to a first preset current; the control unit is also used to control the battery charger to be turned off when it is determined that the charging voltage of the battery pack meets a preset condition.

[0011] In a possible implementation, the preset condition is that the charging voltage of the battery is greater than a first preset voltage or the charging voltage difference of the battery pack within a preset time period is greater than or equal to a first preset threshold.

[0012] In a possible implementation, the control unit is further configured to: control the detection unit to detect the voltage of the battery pack, and when it is determined that the voltage of the battery pack is lower than or equal to a second preset voltage, control the battery charger to start.

[0013] In a possible implementation, the control unit is further configured to: when it is determined that the charging current difference of the battery pack within the preset time period is greater than or equal to a second preset threshold, control the battery charger to be turned off.

[0014] In a third aspect, an embodiment of the present application provides a control device for a battery charger, the device comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method provided in the first aspect of the present application and any possible design thereof.

[0015] In addition, the technical effects brought about by the second to third aspects and any possible designs thereof can refer to the technical effects brought about by the different designs in the first aspect of the embodiment of the present application, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings introduced below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 A schematic structural diagram of a battery charger provided in an embodiment of the present application;

[0018] Figure 2 A flow chart of a control method for a battery charger provided in an embodiment of the present application Figure 1 ;

[0019] Figure 3 A battery charger output parameter fluctuation diagram when a battery pack is disconnected provided in an embodiment of the present application;

[0020] Figure 4 A flow chart of a control method for a battery charger provided in an embodiment of the present application Figure 2 ;

[0021] Figure 5 A flow chart of a control method for a battery charger provided in an embodiment of the present application Figure 3 ;

[0022] Figure 6 A schematic structural diagram of a control device for a battery charger provided in an embodiment of the present application;

[0023] Figure 7 A schematic structural diagram of a battery charger control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0025] The terms used in the implementation methods section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application. Obviously, the embodiments described are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0026] The application scenarios of the control method of the battery charger in the embodiment of the present application are described in detail below with reference to the accompanying drawings.

[0027] The battery charger control method of the present invention can be executed by a controller within a battery charger. The battery charger is connected between the battery pack and the DC bus in the UPS, converting the DC bus voltage into a charging voltage for the battery pack and charging the battery pack. The battery pack may include multiple batteries, which may be connected in parallel or in series.

[0028] See also Figure 1 As shown in FIG, a structural diagram of a battery charger is shown. Figure 1 As shown in the figure, BUS+ is the high-level potential of the DC bus in the UPS system, BUS- is the low-level potential of the DC bus, Bat+ is the positive terminal of the battery pack, and Bat- is the negative terminal of the battery pack. The battery charger is connected between the high-level potential of the DC bus BUS+ and the positive terminal of the battery pack Bat+, and between the low-level potential of the DC bus BUS- and the negative terminal of the battery pack Bat-.

[0029] It should be noted that in Figure 1 In the battery charger shown, the battery pack has two batteries. In practice, the number of batteries in the battery pack is not limited to two. The specific value can be set according to the requirements of the back-end connected load on the backup time and backup power. Figure 1 In the embodiment, two batteries of the battery pack are connected in series. In practice, multiple batteries in the battery pack can also be connected in parallel.

[0030] To ensure the battery pack has sufficient energy to power the load in the event of a grid failure, when the grid is operating normally and the DC bus is supplied with grid-transmitted energy, the battery charger can use this energy to charge the battery pack and fully charge it, ensuring that the stored energy in the battery pack can meet the load's power needs in the event of a grid failure. When the battery charger is turned on, under normal circumstances, as the battery pack charges over time, the battery pack voltage gradually increases and the charging current gradually decreases. At this point, if the battery pack fails and is disconnected from the battery charger, the charging current during the float charge state and the current on the line when the battery pack is disconnected due to a fault are both near zero. Therefore, the charge controller cannot detect whether the current state is the float charge state (as seen when the battery pack is normally connected) or the fault state (as seen when the battery pack is disconnected).

[0031] In order to solve the problem of inaccurate detection of battery pack connection status and ensure the power supply stability of the UPS, the present application proposes a control method for a battery charger, which is described in detail below in conjunction with specific embodiments.

[0032] Need to explain yes, Figure 1 The structure of the battery charger shown is only an example. In practice, the battery charger may adopt other circuit structures commonly used in the industry. In addition, in some embodiments, the battery charger and the battery discharger are two independent devices. In other embodiments, the battery charger and the battery discharger are an integral device, namely a battery charger and discharger. When the battery pack needs to be charged, the battery charger and discharger performs a step-down process to step down the voltage of the DC bus to the charging voltage of the battery pack, thereby charging the battery pack. When the battery pack needs to be discharged, the battery charger and discharger performs a step-up function to step up the voltage of the battery pack to the rated voltage of the DC bus, and supplies power to the load connected to the back end of the DC bus through the DC bus. The following is an example of a battery charger and discharger. Figure 1 Taking the battery charger shown in the figure as an example, the process of detecting the connection status of the battery pack is described.

[0033] like Figure 2 FIG. 1 is a flow chart of a control method for a battery charger provided by the present application. The control method for the battery charger is executed by a controller in the battery charger and includes the following steps:

[0034] Step S201: When it is determined that the battery charger is turned on, the charging current of the battery pack is detected.

[0035] In one example, a controller in a battery charger is connected to an external current sensor and obtains the charging current of the battery pack through the external current sensor.

[0036] In another example, a current sensor for detecting the charging current of the battery pack is provided in the battery charger, and the controller in the battery charger is connected to the current sensor and monitors the charging current of the battery pack through the connected current sensor.

[0037] In one possible implementation, before determining that the battery charger is turned on, the battery charger is in the off state or the battery pack is in the floating charge state. If the battery charger is in the off state, in order to ensure that the battery pack has sufficient power, the controller can monitor the voltage of the battery pack. When it is determined that the voltage of the battery pack is lower than or equal to the second preset voltage, it is determined that the remaining power of the battery pack is insufficient, and the battery charger can be controlled to turn on. After the battery charger is turned on, the battery pack is charged. If the battery pack is in the floating charge state, the charging current of the battery pack is close to zero, and the voltage of the battery pack can be detected. When it is determined that the voltage of the battery pack is greater than the third preset voltage, the battery pack may have an open circuit or other fault, and a battery pack fault alarm can be issued. Among them, the second preset voltage can be set according to the remaining capacity of the battery pack and the application scenario of the battery pack, and this application does not make too many restrictions here. The third preset voltage can be the maximum voltage of the battery pack when the battery pack is in the floating charge state, and its specific value can be selected according to the specifications of the battery pack. Among them, the voltage of the battery pack used by the controller to detect whether it is started can be the positive pole voltage of the battery pack.

[0038] Step 202 : If the charging current of the battery pack is less than or equal to the first predetermined current, monitor the charging voltage of the battery pack.

[0039] In one example, a controller in a battery charger is connected to an external voltage sensor, and obtains a charging voltage amplitude of the battery pack through the external voltage sensor.

[0040] In another example, a voltage sensor for detecting the charging voltage of the battery pack is provided in the battery charger, and the controller is connected to the voltage sensor and monitors the charging voltage of the battery pack through the voltage sensor.

[0041] In one possible implementation, when the controller detects that the charging current of the battery pack is greater than a first preset current, if the controller detects that the charging current difference of the battery pack within a preset time period is greater than or equal to a second preset threshold, that is, the charging current of the battery pack drops or rises rapidly in a short period of time, it can be determined that an internal component of the battery charger is faulty, resulting in the battery charger being unable to charge the battery pack normally. For example, Figure 1Taking the battery charger shown in the figure as an example, when the switch Q1 connected to the DC bus is turned off, although the energy storage element in the battery charger will continue to flow, the charging current of the battery pack will still drop rapidly. When a short circuit occurs in the battery pack or battery charger, the charging current of the battery pack will rise rapidly. In order to protect the safety of the battery charger and other connected devices, the battery charger can be controlled to shut down. The second preset threshold value can be set according to the device parameters in the battery charger, which will not be described in detail in this application.

[0042] Step 203: When it is determined that the charging voltage of the battery pack meets a preset condition, control the battery charger to be turned off.

[0043] When judging the connection status of the battery pack, when the battery pack is connected normally, the proportional-integral controller in the controller will detect the charging current of the battery pack, compare the detected charging current with the given value, and control the on and off of the switch inside the battery charger based on the error between the actual charging current and the given value, thereby adjusting the charging current of the battery pack to the given value. When the battery pack fails and is disconnected from the battery charger, the battery charger and the battery pack are in an open circuit state, and the charging current of the battery pack is reduced to zero. See Figure 3 As shown, the integrator in the proportional-integral controller detects the error in the charging current when the battery pack is disconnected due to a fault. To ensure that the battery pack's charging current is consistent with a given value, the PI controller within the controller automatically controls the battery charger to generate a charging voltage with a larger amplitude. The controller can determine that the battery pack is disconnected due to a fault if it detects an increase in the battery pack's charging voltage, or a significant increase in the charging voltage within a short period of time. Therefore, the preset condition can be set as the battery pack's charging voltage being greater than a second preset voltage, or the battery pack's charging voltage difference within a preset time period being greater than or equal to a first preset threshold.

[0044] The second preset voltage can be set by parameters of a PI controller in the controller. The first preset difference can be set according to a preset time length and parameters of the PI controller.

[0045] In combination with the above description, according to different battery pack connection judgment conditions, the embodiment of the present application can adopt two methods to control the operation process of the battery charger, which are introduced below with reference to the accompanying drawings.

[0046] See also Figure 4 As shown in FIG, a control flow chart of a battery charger is shown, which specifically includes the following steps:

[0047] Step S401 , detect the voltage of the battery pack, and then proceed to step 402 .

[0048] Step S402 , determining whether the voltage of the battery pack is equal to or lower than a second preset voltage; if so, executing step S403 ; otherwise, executing step S409 .

[0049] Step S403: Control the battery charger to start, and execute step S404.

[0050] Step S404: Detect the charging current of the battery pack, and then execute step S405.

[0051] Step S405 , determining whether the charging current of the battery pack is less than or equal to a first preset current; if so, executing step S406 ; otherwise, executing step S408 .

[0052] Step S406 , determining whether the charging voltage of the battery pack is greater than or equal to the first preset voltage; if so, executing step S407 ; otherwise, executing step S404 .

[0053] Step S407: Control the battery charger to be turned off.

[0054] Step S408 , determining whether the charging current difference of the battery pack within the preset time period is greater than or equal to a second preset threshold; if so, executing step S407 ; otherwise, executing step S404 .

[0055] Step S409 , determining whether the voltage of the battery pack is greater than the third preset voltage; if so, executing step S410 ; otherwise, returning to executing step S401 .

[0056] Step S410: Battery pack failure alarm.

[0057] See also Figure 5 As shown, it is another logic diagram of the battery charger control method provided by the embodiment of the present application, as shown Figure 5 As shown, the specific steps include:

[0058] Step S501: Detect the voltage of the battery pack, and then proceed to step S502.

[0059] Step S502 , determining whether the voltage of the battery pack is equal to or lower than a second preset voltage; if so, executing step S503 ; otherwise, executing step S509 .

[0060] Step S503: Control the battery charger to start, and execute step S504.

[0061] Step S504: Detect the charging current of the battery pack, and execute step S505.

[0062] Step S505 , determining whether the charging current of the battery pack is less than or equal to a first preset current; if so, executing step S506 ; otherwise, executing step S508 .

[0063] Step S506 , determining whether the charging voltage difference of the battery pack within the preset time period is greater than or equal to a first preset threshold; if so, executing step S507 ; otherwise, executing step S504 .

[0064] Step S507: Control the battery charger to be turned off.

[0065] Step S508 , determining whether the charging current difference of the battery pack within the preset time period is greater than or equal to a second preset threshold; if so, executing step S507 ; otherwise, executing step S504 .

[0066] Step S509 , determining whether the voltage of the battery pack is greater than the third preset voltage; if so, executing step S510 ; otherwise, returning to executing step S501 .

[0067] Step S510: Battery pack failure alarm.

[0068] Based on the same inventive concept, an embodiment of the present application further provides a structural diagram of a control device for a battery charger. The device can execute the process of the control method for the battery charger, and the device specifically includes: a detection unit 601 and a control unit 602.

[0069] The control unit 602 is configured to control the detection unit 601 to detect the charging current of the battery pack when the battery charger is determined to be on; and to control the detection unit 601 to detect the charging voltage of the battery pack when the battery charger is determined to be less than or equal to a first preset current. The control unit 602 is further configured to control the battery charger to be off when the battery charger is determined to be on.

[0070] In a possible implementation, the preset condition stored in the control unit 602 is that the charging voltage of the battery is greater than a first preset voltage or the charging voltage difference of the battery pack within a preset time period is greater than or equal to a first preset threshold.

[0071] In a possible implementation, the control unit 602 is further configured to: control the detection unit 602 to detect the voltage of the battery pack, and control the battery charger to start when it is determined that the voltage of the battery pack is lower than or equal to a second preset voltage.

[0072] In a possible implementation, the control unit 602 is further configured to: when it is determined that the charging current difference of the battery pack within the preset time period is greater than or equal to a second preset threshold, control the battery charger to be turned off.

[0073] Based on the same inventive concept, the present application also provides a battery charger control device in an embodiment, which can realize the functions of the aforementioned battery charger control device. Figure 7 , electronic equipment includes:

[0074] At least one processor 701, and a memory 702 connected to the at least one processor 701. The specific connection medium between the processor 701 and the memory 702 is not limited in the embodiment of the present application. Figure 7 In the example, the processor 701 and the memory 702 are connected via a bus 700. Figure 7 The bus 700 can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, Figure 7 The diagram is represented by only one thick line, but this does not mean that there is only one bus or one type of bus. Alternatively, the processor 701 may also be referred to as a controller, without limitation to the name.

[0075] In the embodiment of the present application, the memory 702 stores instructions that can be executed by at least one processor 701. The at least one processor 701 can execute the battery parallel management method discussed above by executing the instructions stored in the memory 702. The processor 701 can implement Figure 6 The functions of each module in the device shown.

[0076] Among them, the processor 701 is the control center of the device, which can use various interfaces and lines to connect the various parts of the entire control device, and monitor the device as a whole by running or executing instructions stored in the memory 702 and calling data stored in the memory 702, the various functions of the device and processing data.

[0077] In one possible design, processor 701 may include one or more processing units. Processor 701 may integrate an application processor and a modem processor. The application processor primarily processes the operating system, user interface, and application programs, while the modem processor primarily processes wireless communications. It is understood that the modem processor may not be integrated into processor 701. In some embodiments, processor 701 and memory 702 may be implemented on the same chip. In some embodiments, they may also be implemented on separate chips.

[0078] The processor 701 can be a general-purpose processor, such as a central processing unit (CPU), a digital signal processor, an application-specific integrated circuit, a field-programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this application. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the battery parallel management method disclosed in the embodiments of this application can be directly implemented as a hardware processor, or can be implemented using a combination of hardware and software modules in the processor.

[0079] The memory 702 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules. The memory 702 may include at least one type of storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory, a random access memory (Random Access Memory, RAM), a static random access memory (Static Random Access Memory, SRAM), a programmable read-only memory (Programmable Read Only Memory, PROM), a read-only memory (Read Only Memory, ROM), an electrically erasable programmable read-only memory (Electrically Erasable Programmable Read-Only Memory, EEPROM), a magnetic memory, a disk, an optical disk, etc. The memory 702 is any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer, but is not limited thereto. The memory 702 in the embodiment of the present application can also be a circuit or any other device that can realize a storage function, for storing program instructions and / or data.

[0080] By designing and programming the processor 701, the code corresponding to the battery parallel management method described in the above embodiment can be fixed into the chip, so that the chip can execute the code when running. Figure 3 The steps of the battery parallel management method of the embodiment shown are as follows: How to design and program the processor 701 is well known to those skilled in the art and will not be described in detail here.

[0081] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0082] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0083] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0084] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0085] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for controlling a battery charger, characterized in that: include: When it is determined that the battery charger is turned on, detecting a charging current of the battery pack; If the charging current of the battery pack is less than or equal to a first preset current, monitoring the charging voltage of the battery pack; When it is determined that the charging voltage of the battery pack meets a preset condition, the battery charger is controlled to be turned off.

2. The method according to claim 1, characterized in that The preset condition is that the charging voltage of the battery is greater than a first preset voltage or the charging voltage difference of the battery pack within a preset time period is greater than or equal to a first preset threshold.

3. The method according to claim 1 or 2, characterized in that Before determining that the battery charger is turned on, the method further includes: The voltage of the battery pack is monitored, and when it is determined that the voltage of the battery pack is lower than or equal to a second preset voltage, the battery charger is controlled to start.

4. The method according to claim 1 or 2, characterized in that The method further comprises: When it is determined that the charging current difference of the battery pack within the preset time period is greater than or equal to a second preset threshold, the battery charger is controlled to be turned off.

5. A control device for a battery charger, characterized in that: The device comprises: a detection unit and a control unit; The control unit is configured to control the detection unit to detect the charging current of the battery pack when it is determined that the battery charger is turned on; and control the detection unit to detect the charging voltage of the battery pack when it is determined that the charging current of the battery pack is less than or equal to a first preset current; The control unit is further configured to control the battery charger to be turned off when it is determined that the charging voltage of the battery pack meets a preset condition.

6. The device according to claim 5, characterized in that The preset condition is that the charging voltage of the battery is greater than a first preset voltage or the charging voltage difference of the battery pack within a preset time period is greater than or equal to a first preset threshold.

7. The device according to claim 5 or 6, characterized in that The control unit is further configured to: The detection unit is controlled to detect the voltage of the battery pack, and when it is determined that the voltage of the battery pack is lower than or equal to a second preset voltage, the battery charger is controlled to be turned on.

8. The device according to claim 5 or 6, characterized in that The control unit is further configured to: When it is determined that the charging current difference of the battery pack within the preset time period is greater than or equal to a second preset threshold, the battery charger is controlled to be turned off.

9. A control device for a battery charger, characterized in that: include: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the battery charger control method according to any one of claims 1 to 4.

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