WO2024077707A1 - Battery pack, heating control method thereof, and electronic device - Google Patents

Abstract

A battery pack, comprising: a switch unit, a battery unit, a heating unit, a buck unit and an interface unit. In addition to the heating unit, the buck unit is additionally arranged in the battery pack to be used for controlling the working voltage of the heating unit. When the battery pack is at a low temperature, the buck unit is regulated to output a constant voltage to supply power to the heating unit when a power supply is connected and the switch unit is in an off state. When the voltage supplied by the power supply decreases, the output voltage output to the heating unit is decreased by means of the buck unit.

Description

Battery pack and heating control method thereof, and electronic device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to the Chinese patent application filed with the China Patent Office on October 13, 2022, with application number 202211256938.0 and invention name “Battery Pack and Heating Control Method and Electronic Device”, the entire contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of battery heating technology, and in particular to a battery pack and a heating control method thereof, and an electronic device.

Background technique

The statements herein merely provide background information related to the present application and do not necessarily constitute exemplary techniques.

Batteries (such as lithium iron phosphate batteries) are often used in household energy storage, mobile energy storage, solar and wind power generation and energy storage equipment, etc. They have the advantages of fast charging and high temperature resistance. However, the battery performance is poor at low temperatures, resulting in the equipment using the battery not being able to work properly at low temperatures. For rechargeable lithium batteries, it is impossible to charge the lithium battery at low temperatures, so a heating device is often added to heat the battery.

However, when heating the battery, the related solutions may fail to heat normally when the external energy provided is low. For example, they may not be able to heat continuously or need to consume battery energy to heat themselves, which may easily damage the battery and reduce battery performance.

Summary of the invention

According to various embodiments of the present application, a battery pack and a heating control method thereof, an electronic device, a computer-readable storage medium, and a computer program product are provided.

According to one aspect of the embodiment of the present application, a battery pack is provided, comprising a switch unit, a battery unit, a heating unit, a buck unit, an interface unit and a controller; the interface unit is used to connect to a power supply or a load; the battery unit is used to connect to the interface unit via the switch unit; the two ends of the heating unit are connected in parallel to the output end of the buck unit; the input end of the buck unit is connected to the interface unit, the buck unit is used to convert the input voltage of the power supply into an output voltage and then output it to the heating unit; the heating unit is used to heat the battery pack under the control of the output voltage. The controller is used to: when the temperature of the battery pack is less than a first preset temperature, obtain the access state of the power supply and the on-off state of the switch unit; when the power supply is connected and the switch unit is in the off state, control the output voltage of the buck unit to maintain at the first preset voltage; when the input voltage of the buck unit is less than or equal to the first voltage threshold, control the output voltage of the buck unit to decrease from the first preset voltage until the input voltage of the buck unit is greater than or equal to the second voltage threshold; the second voltage threshold is greater than the first voltage threshold, and the second voltage threshold is greater than the reference voltage of the battery pack.

According to one aspect of an embodiment of the present application, a battery pack heating control method is also provided, including: when the temperature of the battery pack is lower than a first preset temperature, obtaining the connection status of the power supply and the on-off status of the switch unit; when the power supply is connected and the switch unit is in the off state, controlling the output voltage of the step-down unit to remain at a first preset voltage; when the input voltage of the step-down unit is lower than or equal to a first voltage threshold, controlling the output voltage of the step-down unit to decrease from the first preset voltage until the input voltage of the step-down unit is greater than or equal to a second voltage threshold; the second voltage threshold is greater than the first voltage threshold, and the second voltage threshold is greater than the reference voltage of the battery pack.

According to one aspect of an embodiment of the present application, there is also provided an electronic device, comprising: one or more processors; a battery pack as described above; and a storage device for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the electronic device implements the battery pack heating control method as described above.

According to one aspect of an embodiment of the present application, a computer-readable storage medium stores computer-readable instructions thereon. When the computer-readable instructions are executed by a processor of a computer, the computer executes the battery pack heating control method as described above.

According to one aspect of the embodiments of the present application, a computer program product or a computer program is provided, the computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the battery pack heating control method provided in the above various optional embodiments.

The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims.

It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. Obviously, the accompanying drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

FIG1 is a schematic diagram of an implementation environment involved in the present application.

FIG. 2 is a schematic structural diagram of a battery pack according to an exemplary embodiment of the present application.

FIG. 3 is a schematic diagram of a circuit structure of a battery pack according to an exemplary embodiment of the present application.

FIG. 4 is a flow chart of a battery pack heating control method implemented by a controller of a battery pack according to an exemplary embodiment of the present application.

FIG. 5 is a flow chart of step S402 in the embodiment shown in FIG. 4 in an exemplary embodiment.

FIG. 6 is a flow chart of step S403 in the embodiment shown in FIG. 4 in an exemplary embodiment.

FIG. 7 is a flow chart of a battery pack heating control method implemented by a controller of a battery pack according to another exemplary embodiment of the present application.

FIG8 is a flowchart of the steps of controlling the heating unit to stop working in a battery pack heating control method of the present application in an exemplary embodiment.

FIG9 is a flow chart of the steps of controlling the heating unit to stop working in a battery pack heating control method of the present application in an exemplary embodiment.

FIG. 10 is a schematic diagram of the structure of an electronic device suitable for implementing an embodiment of the present application.

Detailed ways

Here, exemplary embodiments will be described in detail, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and/or processor devices and/or microcontroller devices.

The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations/steps, nor must they be executed in the order described. For example, some operations/steps can be decomposed, and some operations/steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

The term "plurality" used in this application refers to two or more than two. "And/or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and/or B can represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. The character "/" generally indicates that the related objects are in an "or" relationship.

In the related art, energy storage batteries such as lithium iron phosphate batteries are often used in household energy storage, mobile energy storage, solar and wind power generation energy storage equipment and other equipment, and have the advantages of fast charging and high temperature resistance. However, the battery performance is poor at low temperatures, resulting in the equipment using the battery not being able to work properly at low temperatures. Taking lithium iron phosphate batteries as an example, the performance on the charged lithium iron phosphate batteries is: the lithium iron phosphate battery cannot be charged under low temperature conditions. Because when charging at low temperatures, the embedding and lithium plating reactions of lithium ions on the graphite electrodes in the battery exist simultaneously and compete with each other, and the diffusion of lithium ions in graphite is inhibited under low temperature conditions, which reduces the conductivity of the electrolyte, thereby reducing the embedding rate and making the lithium plating reaction more likely to occur on the graphite surface.

In order to charge the battery normally under low temperature conditions, an external heating device is often used to heat the battery and raise the battery temperature so that the battery is at a temperature value that can be charged normally. However, this method requires a large amount of external energy to heat the battery, otherwise the battery energy will be consumed to the heating device, or the heating will be stopped directly. The above operations will cause the battery to fail to heat normally, which is easy to damage the battery and reduce the battery performance and service life.

In order to solve the above problems, the embodiments of the present application propose a battery pack and a heating control method thereof, an electronic device, and a computer-readable storage medium, which mainly relate to battery heating technology. These embodiments will be described in detail below.

First, please refer to FIG. 1, which is a schematic diagram of an implementation environment involved in the present application. The implementation environment includes a power supply 10 and a battery pack 20. The power supply 10 is provided with a battery interface, and the battery pack 20 can be connected to the power supply 10 through the battery interface. When the battery pack is connected and the battery pack 20 needs to be charged, the power supply 10 can charge the battery pack 20.

In some embodiments, the power supply 10 is also provided with a load interface (not shown in FIG. 1 ) for connecting to a load. When the battery pack 20 and the load are connected at the same time, the battery pack 20 can supply power to the load via the power supply 10 .

It can be understood that the battery pack 20 includes a controller (not shown in FIG. 1 ), and the charge and discharge control and heating control of the battery pack 20 can be performed by the controller.

It can be understood that in some embodiments, the power supply 10 is directly connected to the load, and the power supply 10 directly supplies power to the load, which is not limited in the present application.

It can be understood that in some embodiments, the power supply 10 may include a DC power supply such as a solar photovoltaic panel, or an AC power supply such as a mains power supply, and the present application does not impose any limitation on this.

Please refer to FIG. 2 , which is a schematic diagram of a circuit structure of a battery pack 20 according to an exemplary embodiment of the present application.

As shown in FIG2 , the battery pack 20 includes a switch unit 21, a battery unit 22, a heating unit 23, a voltage reduction unit 24, and an interface unit 25. The interface unit 25 is used to connect to the power supply 10, and can connect the power supply 10 to the battery pack 20. The battery unit 22 is connected to the interface unit 25 via the switch unit 21, and the on and off of the charge and discharge circuit of the battery unit 22 is realized by controlling the on and off of the switch unit 21. The two ends of the heating unit 23 are connected in parallel to the output end of the voltage reduction unit 24. The heating unit 23 is used to receive the output voltage of the voltage reduction unit 24 and heat the battery pack 20 according to the output voltage. The input end of the voltage reduction unit 24 is connected to the interface unit 25. The voltage reduction unit 24 is used to convert the input voltage of the power supply 10 and output it to the heating unit 23. The voltage reduction unit 24 controls the voltage output to the heating unit 23 during the voltage conversion process to control the heating power of the heating unit 23.

In the above embodiment, in addition to the heating unit 23, the battery pack 20 also has a step-down unit 24, and the controller controls the working voltage of the heating unit 23 through the step-down unit 24. When the temperature of the battery pack is lower than the first preset temperature, the controller controls the step-down unit 24 to output a constant voltage to power the heating unit 23. When the heating unit 23 receives the constant voltage, it can heat the battery cell 22 with a constant power to quickly heat it up. When the voltage provided by the power supply 10 decreases, the power provided by the power supply 10 decreases. At this time, the controller controls the output voltage of the step-down unit 24 to reduce the heating power of the heating unit 23 to the battery cell 22, so that the power supply 10 can meet the power demand of the heating unit 23, avoid consuming the energy of the battery cell 22 to the heating unit 23, and at the same time, maintain the heating unit 23 to continue working, so that the temperature of the battery cell 22 does not drop and cannot be charged normally, thereby protecting the battery cell 22 to the greatest extent and maintaining the battery performance while the battery cell 22 continues to be heated.

Please refer to FIG. 3 , which is a schematic diagram of an equivalent circuit structure of the battery pack 20 and the power supply 10 in the implementation environment shown in FIG. 1 in one embodiment.

The battery pack 20 includes a switch unit 21, a battery unit 22, a heating unit 23, a voltage reduction unit 24 and an interface unit 25, and the connection relationship between the units is consistent with that shown in FIG2. The power supply 10 includes a voltage conversion unit 11 and a photovoltaic panel 14. The power supply 10 is provided with a battery interface 12 for connecting the battery pack 20, and the battery pack 20 is connected to the voltage conversion unit 11 via the battery interface 12. The voltage conversion unit 11 is provided with a power input interface 13 for connecting to the photovoltaic panel 14. The DC voltage output by the photovoltaic panel 14 can be used to charge the battery pack 20 or supply power to the load after the voltage conversion unit 11 performs voltage conversion.

In one embodiment, the voltage conversion unit 11 may be integrated with the battery pack 20 on the same device, or may be integrated on an independent power conversion device.

In some embodiments, the power supply 10 also includes a load interface (not shown) for connecting to a load. When the load is connected, it is equivalent to connecting to both ends of the battery interface 12. It can be powered by the battery pack 20, or by the power supply 10, or by both at the same time.

It can be understood that in some embodiments, the voltage conversion unit 11 can be omitted in the power supply 10. In this case, the power supply 10 directly provides the voltage output by the photovoltaic panel 14 to the battery pack 20 or the load.

In some embodiments, a capacitor C2 is connected in parallel to the battery interface 12 of the power supply 10, and the capacitor C2 is referred to as a port capacitor in the present application. When the power supply 10 supplies power to a load or charges the battery pack 20, the voltage of the port capacitor is the output voltage of the power supply 10. A current sensing device, such as the current sensing resistor R2 in FIG. 3 , may be provided on the output circuit of the port capacitor C2 to detect the output current of the power supply 10. Similarly, a current sensing device, such as the current sensing resistor R1 in FIG. 3 , may also be provided on the charge and discharge circuit of the battery pack 20 to detect the charge and discharge current of the battery pack 20.

It is understood that in some embodiments, the power supply 10 may be composed of a voltage conversion device and an external power supply. In this case, the photovoltaic panel 14 is an independent power supply, and the voltage conversion unit 10 may be a voltage conversion device such as a DC-DC conversion device, a DC-AC bidirectional conversion device, etc., which is not limited in this application.

As shown in FIG3 , the power source in the power supply 10 may be a photovoltaic panel. Of course, the power supply 10 is not limited to photovoltaic panels, and may be other power sources in actual applications, such as a DC power supply, an AC power supply, or a combination of the above different types of power inputs.

As shown in FIG3 , the switch unit 21 includes a first switch tube Q1 and a second switch tube Q2. It can be understood that in the present application, the switch tube can be a MOS tube (MOSFET, Metal-Oxide-Semiconductor Field-Effect Transistor, Metal-Oxide Semiconductor Field-Effect Transistor, referred to as MOSFET), IGBT tube (Insulated Gate Bipolar Transistor, Insulated Gate Bipolar Transistor) and other switch tubes with switching functions, and the present application does not limit this, and the following description will be continued by taking the MOS tube as an example.

It can be understood that, as shown in FIG3 , the switch unit 21 is formed by the first switch tube Q1 and the second switch tube Q2 connected in reverse series to form a bidirectional switch, which can achieve bidirectional cutoff to control the conduction or disconnection of the charging and discharging circuit of the battery unit 22. When it is detected that the temperature of the battery pack 20 is lower than the first preset temperature, the on-off state of the switch unit 21 is obtained, and the access state of the power supply 10 is received at the power supply 10. When the temperature of the battery pack 20 is lower than the first preset temperature, the switch unit 21 will disconnect the charging circuit to avoid charging the battery pack 20.

It should be noted that when the switch unit 21 includes two MOS tubes, the conduction state of the switch unit 21 represents the situation where the first switch tube Q1 and the second switch tube Q2 are turned on at the same time. When accepting charging, the switch unit 21 is turned off, which represents the situation where the first switch tube Q1 is turned on and the second switch tube Q2 is turned off. At this time, the charging circuit is cut off, but discharging is allowed. In one embodiment, the switch unit 21 can also be turned off as the first switch tube Q1 and the second switch tube Q2 are both turned off. At this time, the battery is not allowed to be charged or discharged.

Please continue to refer to FIG. 3 . As shown in the figure, the battery unit 22 may include one or more single cells, for example, formed by connecting a plurality of single cells in parallel or in series, and the present application does not impose any limitation on this.

Please continue to refer to Figure 3. As shown in the figure, the heating unit 23 is arranged in the battery pack 20, and is used to heat the battery pack 20. The heating unit 23 is formed by a heating resistor R3. It can be understood that in some embodiments, the heating unit 23 may also include a switch connected in series with the heating resistor R3. The number of heating resistors and switches can be one or more. By setting the switch, the operation or non-operation of the heating unit 23 can be controlled to further ensure that the heating unit 23 is connected or disconnected from the circuit. When the heating unit 23 is prohibited from working, the control switch is disconnected, and the heating unit 23 is not connected to the circuit. When the heating unit 23 is allowed to work, the control switch is turned on, and the heating unit 23 is connected to the circuit to work.

Please continue to refer to Figure 3. As shown in the figure, the buck unit 24 is arranged between the interface unit 25 of the battery pack and the heating unit 23, and is used to convert the voltage input by the power supply 10 through the interface unit 25 to supply power to the heating unit 23. In some embodiments, the buck unit 24 includes a BUCK circuit composed of two switch tubes Q3 and Q4, an inductor L1 and a capacitor C1 as shown in Figure 3. It can be understood that in other embodiments, the buck circuit can also have other composition forms. For example, the switch tube Q3 can be replaced by a diode, and this application does not limit this.

As shown in FIGS. 1 to 3, in one embodiment, a temperature sensor (not shown) is further provided in the battery pack for detecting the temperature of the battery pack itself. The controller (not shown) of the battery pack 20 is used to obtain the access state of the power supply 10 and the on-off state of the switch unit 21 of the battery pack 20 when the temperature sensor detects that its temperature is less than the first preset temperature. When the power supply 10 is connected and the switch unit 21 is in the off state, the output voltage of the voltage reduction unit 24 is controlled to be maintained at the first preset voltage. At this time, the heating unit 23 works at the first preset voltage to heat the battery pack. When the energy provided by the power supply 10 is reduced, so that the input voltage of the voltage reduction unit 24 drops to less than or equal to the first voltage threshold, the output voltage of the voltage reduction unit 24 is controlled to decrease from the first preset voltage until the input voltage of the voltage reduction unit 24 rises again to greater than or equal to the second voltage threshold. In this way, through the operation of the above-mentioned control circuit, it is avoided that when the input of the power supply 10, such as the photovoltaic panel, is too low or the input is unstable, the heating unit 23 directly fails to work normally, and the energy of the battery unit 22 needs to be consumed to supply the heating unit 23, thereby damaging the battery.

In the embodiment of the present application, not only a resistive heating unit 23 is provided to increase the temperature of the battery cell 22, but also a buck unit 24 is added between the heating unit 23 and the external interface of the battery pack. In this way, after receiving the external input voltage, the buck unit 24 can regulate the input voltage so that it outputs a suitable output voltage to the heating unit 23 to drive the heating unit 23 to work. When the power supply 10 is powered normally, the controller can output a constant voltage to power the heating unit 23 by regulating the output voltage of the buck unit 24, so that the battery cell 22 is quickly heated. When the voltage provided by the power supply 10 decreases, the power supply that the power supply 10 can provide decreases. The controller can reduce the output voltage output to the heating unit 23 through the buck unit 24 to reduce the heating power of the heating unit 23, so that the power supply 10 can support the power demand of the heating unit 23, avoid consuming battery energy to heat the heating unit 23 for itself, and at the same time maintain the heating unit 23 to continue working. In this way, while the battery pack 20 is continuously heated, the battery is protected to the greatest extent and the battery performance is maintained.

It can be understood that the circuit structures shown in Figures 1, 2 and 3 are only for illustration, and the circuit structures of the battery pack 20 and the power supply 10 may include more or fewer electrical components than those shown in Figures 1 to 3, or have components different from those shown in Figures 1 to 3. Each component shown in Figures 1 to 3 can be implemented by hardware, software or a combination thereof.

In the embodiments provided in the present application, control of the battery pack 20 and each functional unit and device in the corresponding circuit can be achieved through a controller in the battery pack 20 .

Please refer to FIG. 4, which is a flow chart of a controller implementing a battery pack heating control method shown in an exemplary embodiment of the present application. The method can be applied to the implementation environment shown in FIG. 1 or FIG. 3, and is specifically executed by the controller in the battery pack in the embodiment environment shown in FIG. 1. In other implementation environments, the method can be executed by devices in other implementation environments, and this embodiment does not limit this.

The following describes the battery pack heating control scheme of the embodiment of the present application by taking the execution of the controller in the battery pack as an example.

As shown in FIG. 4 , in an exemplary embodiment, the battery pack heating control method may include steps S401 to S403, which are described in detail as follows:

Step S401, when the temperature of the battery pack is lower than a first preset temperature, obtaining the connection status of the power supply and the on/off status of the switch unit.

During the charging process of the battery cells, the temperature of the battery pack will be detected in real time, for example, by setting a temperature sensor on the battery pack to detect the temperature in real time. When it is detected that the temperature of the battery pack is lower than the first preset temperature, that is, the battery pack is in a low temperature state, the battery pack will be in a poor charging performance due to the low temperature, so that the current battery cannot be charged normally. To avoid charging failures, the controller controls the switch unit to be in the off state to perform charging low temperature protection, that is, the charging circuit of the battery cell is cut off, the first switch tube of the switch unit remains on, and the second switch tube remains off. At this time, the battery pack heating control method provided in the present application can be implemented to control the heating of the battery pack.

When it is detected that the temperature of the battery pack is lower than the first preset temperature, the access status of the power supply and the on/off status of the switch unit are obtained, and the heating unit is controlled by the access status and the on/off status. The specific value of the first preset temperature can be set according to actual needs. For example, the first preset temperature can be 2 degrees Celsius, 5 degrees Celsius or other temperature values, as long as it meets the temperature threshold that can reflect the poor low-temperature characteristics of the lithium iron carbonate battery, and no specific restrictions are made here.

Step S402: when the power supply is connected and the switch unit is in the off state, the output voltage of the voltage reduction unit is controlled to be maintained at a first preset voltage.

The access status of the power supply and the on-off status of the switch unit can be obtained directly or indirectly. Taking the structure of the battery pack in the embodiment shown in Figures 2 and 3 as an example, the access status of the power supply can be confirmed according to the access status of the power input interface. For example, when the photovoltaic panel is connected, the access status of the power input interface in the power supply is characterized as PV power access, indicating that the power supply is connected at this time. When the power supply is detected to be connected, it means that there is a power supply that can charge the battery pack, and at the same time, it is detected that the switch unit is in the off state, indicating that the battery pack is in a low temperature state, resulting in the charging circuit of the battery unit not forming a path, that is, the power supply does not charge the battery unit. Based on this, when it is detected that the power supply is connected and the switch unit is in the off state, the controller controls the output voltage of the step-down unit to remain at the first preset voltage, so that the heating unit works based on the constant power corresponding to the first preset voltage to heat the battery unit and quickly increase the temperature of the battery pack. Among them, the specific value of the first preset voltage can be set according to actual needs, or it can be set according to conventional settings, and there is no limitation here.

Step S403, when the input voltage of the step-down unit is less than or equal to the first voltage threshold, controlling the output voltage of the step-down unit to decrease from the first preset voltage until the input voltage of the step-down unit is greater than or equal to the second voltage threshold.

After controlling the output voltage of the step-down unit to maintain at the first preset voltage, the controller will monitor the output voltage of the power supply, that is, the input voltage of the step-down unit, and compare the input voltage of the step-down unit with the preset first voltage threshold. The output voltage of the power supply is positively correlated with the power supply of the power supply. When the power supply of the power supply decreases, the input voltage of the step-down unit will also decrease accordingly. When the input voltage of the step-down unit is less than or equal to the first voltage threshold, the output voltage of the step-down unit is controlled to decrease from the first preset voltage until the input voltage of the step-down unit is greater than or equal to the second voltage threshold, and then the control of the output voltage of the step-down unit is stopped. In this way, by reducing the output voltage of the step-down unit, the working voltage of the heating unit is reduced to reduce the heating power, which can avoid consuming battery energy for self-heating. At the same time, it can also avoid the heating unit from stopping working, and the battery pack temperature cannot be maintained and drops again.

It can be understood that in some embodiments, when the controller starts to control the heating of the battery pack, it will obtain the reference voltage of the battery pack. The reference voltage can be determined based on the minimum voltage across the battery cell after the battery pack is connected to the power supply to activate the battery. The voltage is generally determined by the voltage of the battery pack during stable charging and discharging, that is, the platform voltage of the battery pack. It can be understood that after the battery is activated, the target output voltage of the power supply, that is, the target input voltage of the buck unit is generally greater than the reference voltage, for example, the target input voltage of the buck unit V _{in_ref} =V _bat +1, where V _bat is the reference voltage of the battery pack. In the embodiment of the present application, the first voltage threshold and the second voltage threshold are pre-set based on the reference voltage, wherein the reference voltage value is less than the second voltage threshold, and the second voltage threshold is greater than the first voltage threshold, and the first voltage threshold and the second voltage threshold can be specific values, or can be a threshold range including a maximum value and a minimum value, and the existence of an error value is allowed, which is not limited here. For example, the first voltage threshold can be V ₁ =V _{in_ref} -1 =V _{bat, and} the second voltage threshold can be V ₂ =V _{in_ref} +1.

It can be understood that by setting the first voltage threshold and the second voltage threshold, it is possible to avoid the input voltage of the buck unit fluctuating around the reference voltage, and to avoid the controller repeatedly adjusting the duty cycle of the drive signal and stopping adjusting the duty cycle of the drive signal, thereby affecting the normal operation of the circuit.

When the input voltage of the step-down unit is less than the first voltage threshold, that is, it may be less than the battery cell voltage, if the heating unit still maintains the first preset voltage to work, and the power required is greater than the power provided by the power supply, the input voltage of the step-down unit will be continuously reduced, so that the battery cell voltage is higher than the input voltage of the step-down unit. Due to the existence of the voltage difference, the battery cell will inevitably supply power to the heating unit, thereby causing a discharge current to appear in the charge and discharge circuit. The discharge current passes through the body diode of the second switch tube Q2. To protect the device, the second switch tube Q2 of the switch unit will be turned on. At this time, the energy of the battery cell will continue to be consumed. Therefore, when the input voltage of the step-down unit is less than or equal to the first voltage threshold, the controller adjusts the output voltage of the step-down unit to reduce it, and the working power of the heating unit is reduced. At this time, the input voltage of the step-down unit will rise again until it is higher than the voltage of the battery cell, and the switch unit can restore the shutdown state under low temperature protection to avoid consuming the energy of the battery cell for heating.

In addition, in the battery pack heating control method provided in the embodiment of the present application, the reason why the voltage provided by the power supply drops, causing the input voltage of the step-down unit to also decrease, may be that the input energy provided by the power supply is unstable, or that a load is connected to the battery pack or the power supply. At this time, the input voltage of the step-down unit will also be lowered.

In some embodiments, the controller is further used to implement the following steps: when the temperature of the battery pack is lower than a first preset temperature, the switch unit is controlled to be turned off.

During the charging process of the battery cell, the temperature of the battery pack is detected in real time, for example, by setting a temperature sensor on the battery pack to detect the temperature in real time. When it is detected that the temperature of the battery pack is lower than the first preset temperature, that is, when the battery pack is in a low temperature state, the battery pack will be in a poor charging performance due to the low temperature, so that the current battery cannot be charged normally. To avoid malfunctions, the controller controls the switch unit to be in the off state for charging low temperature protection, that is, the charging circuit of the battery unit is cut off, the first switch tube Q1 of the switch unit remains on, and the second switch tube Q2 remains off.

In some embodiments, the controller can obtain the on-off state of the switch unit by executing the following steps: monitoring the real-time discharge current value of the battery unit; if it is detected that the real-time discharge current value is less than or equal to the preset current threshold, determining that the switch unit is in the off state.

Specifically, under low temperature conditions, the second switch tube Q2 of the switch unit is in the off state. After the power supply is connected, the power supply power is small, resulting in its output voltage being lower than the battery unit voltage. The battery unit can discharge to the outside through the body diode of the second switch tube, but the discharge current is extremely small. If the discharge current exceeds the preset current threshold, in order to avoid high temperature damage to the MOS tube, the second switch tube will usually be turned on. At this time, the discharge current is much larger than the current when discharging through the body diode. Therefore, if it is detected that the real-time discharge current value is less than or equal to the preset current threshold, it can be confirmed that the switch unit is in the off state.

It can also be understood that in some embodiments, when the controller controls the output voltage of the step-down unit to remain at the first preset voltage, if the load interface of the power supply or the battery pack is connected to the load, the load requires power to operate, and the power of the power supply is insufficient to supply the load and the heating unit. Therefore, the battery unit will consume its own energy to the load, causing the switch unit to turn on.

Please refer to Figure 5, which is a flow chart of step S402 in an exemplary embodiment of the embodiment shown in Figure 4. As shown in Figure 5, step S402 may specifically include steps S501 to S503, and the controller controls the output voltage of the buck unit to remain at the first preset voltage through the above steps, which are described in detail as follows:

Step S501, obtaining the output voltage of the buck circuit.

The controller can control the output voltage of the buck circuit by deviation adjustment, that is, according to the output voltage at the current moment and the target voltage, that is, the voltage difference between the output voltage at the current moment and the first preset voltage, the drive signal of the switch tube of the buck circuit is adjusted by deviation adjustment, so that the output voltage at the next moment is closer to the first preset voltage, so that the output voltage is stabilized near the first preset voltage. The current output voltage of the buck circuit can be obtained by sampling the current output voltage of the buck circuit. For example, taking Figure 3 as an example, the current output voltage of the buck circuit can be obtained by sampling the voltage on both sides of the capacitor C1, so as to adjust the output voltage at the next moment based on the current output voltage.

Step S502, adjusting the duty cycle of the driving signal based on the first preset voltage, the output voltage of the buck circuit and the first deviation adjustment algorithm.

The output voltage of the buck circuit can be regulated based on a preset first deviation adjustment algorithm when the power supply is normal, so as to adjust the duty cycle of the driving signal and thus change the output of the buck circuit.

In some embodiments, the preset first deviation adjustment algorithm can be a proportional integral (proportional integral) adjustment algorithm, which is implemented by a PI regulator, and its transfer function is: H(s)=Kp+Ki/s, wherein Kp is a proportional parameter of the PI controller, Ki is an integral parameter of the PI regulator, and s is a pull variable.

After obtaining the current output voltage of the buck circuit, the voltage difference between the output voltage and the first preset voltage is input as the deviation to the PI regulator, so that the duty cycle of the adjusted drive signal can be obtained, and then the drive of the buck circuit switch tube at the next moment can be determined. It can be understood that adjusting the parameters Ki and Kp of the PI regulator can control the adjustment step of the duty cycle, and then control the adjustment amplitude of the output voltage. For example, each time the duty cycle adjustment step is controlled, each step of adjustment reduces or increases the BUCK output voltage by 0.2V.

Step S503 , driving the buck circuit by using the adjusted driving signal so that the buck circuit outputs a first preset voltage.

Based on the adjusted driving signal obtained above, the switch tube of the buck circuit is controlled to enter the next round of regulation process, so that the output voltage of the buck circuit will be stabilized at the first preset voltage.

It can be understood that the buck circuit outputs the first preset voltage means that the output voltage of the buck circuit is stable near the first preset voltage. For example, if the first preset voltage is V ₀ , then the buck circuit outputs (V ₀ -V _er ) to (V ₀ +V _err ) can be considered as outputting the first preset voltage, _Verr error value. It can be understood that the first preset voltage is less than the target input voltage of the buck circuit, that is, _{Vin_ref mentioned in the previous embodiment.}

In this embodiment, when the power supply to the battery pack is normal, the controller controls the buck circuit output of the step-down unit to maintain a first preset voltage, and controls the heating unit to heat the battery cell based on the first preset voltage, thereby being able to heat the battery pack based on constant power to quickly heat it up.

Please refer to FIG. 6, which is a flow chart of step S403 in an exemplary embodiment of the embodiment shown in FIG. 4. As shown in FIG. 6, step S403 may specifically include steps S601 to S602, and the controller controls the output voltage of the buck unit to decrease from the first preset voltage until the input voltage of the buck unit rises to the second voltage threshold through the above steps, which are described in detail as follows:

Step S601, based on the first voltage threshold, the input voltage of the buck circuit and the second deviation adjustment algorithm, the duty cycle of the driving signal is adjusted, and the duty cycle of the driving signal after the adjustment is smaller than the duty cycle before the adjustment.

When it is determined that the input voltage of the buck circuit of the step-down unit is less than or equal to the first voltage threshold, it means that the input voltage of the buck circuit is already less than the reference voltage of the battery pack, the power supply power connected to the battery pack decreases, and the battery pack may discharge to the outside for the heating unit to work, thereby consuming the battery pack energy for heating.

At this time, the second deviation adjustment algorithm can be used to adjust the duty cycle of the driving signal of the buck circuit. The duty cycle is adjusted based on the deviation between the current input voltage and the first voltage threshold to reduce the duty cycle. When the duty cycle decreases, the output voltage of the buck circuit decreases. After the output voltage decreases, the power consumed by the heating unit decreases, and the input voltage of the buck circuit will increase accordingly. In this way, the input voltage of the buck circuit can be gradually increased by continuously adjusting the duty cycle.

It can be understood that, here, the second deviation adjustment algorithm can be the same adjustment algorithm as the first deviation adjustment, for example, it can be a proportional integral (proportional integral) adjustment algorithm, which is implemented by a PI regulator, and its transfer function is: H(s)=Kp+Ki/s, wherein Kp is the proportional parameter of the PI controller, Ki is the integral parameter of the PI regulator, and s is a pull variable.

It can be understood that the duty cycle after adjustment by the PI regulator is generally decreasing compared to the duty cycle when the buck circuit output voltage is the first preset voltage, but the duty cycle may increase during the entire process of the output voltage recovering to the second voltage threshold.

Step S602 , driving the buck circuit according to the adjusted duty cycle of the driving signal, and stopping adjusting the duty cycle of the driving signal after the input voltage of the buck circuit rises to a second voltage threshold.

The output voltage of the buck circuit will decrease as the duty cycle of the driving signal decreases. When the duty cycle of the driving signal decreases, the output voltage also decreases. After the output voltage decreases, the power consumed by the heating unit decreases, and the input voltage of the buck circuit will increase accordingly. In this way, by continuously adjusting the duty cycle of the driving signal to gradually decrease it, the input voltage of the buck circuit can be gradually increased. When the input voltage of the buck circuit rises to the second voltage threshold, at this time, the voltage value is greater than the reference voltage of the battery pack, which can ensure that the battery pack no longer supplies power to the heating unit, and then the duty cycle of the driving signal can be stopped.

In the above embodiment, when the input voltage of the buck circuit drops, the buck circuit driving signal is adjusted through deviation adjustment, so that the input voltage of the buck circuit can be quickly restored to the second voltage threshold. Even if the switch unit is turned on because the battery cell voltage is greater than the buck circuit input voltage, causing the battery cell to discharge externally, the controller can also quickly adjust to restore the buck circuit input voltage, thereby restoring the switch unit to the shutdown protection state under low temperature, thereby preventing the battery pack from consuming its own energy for heating.

Please refer to Figure 7, which is a flow chart of a battery pack heating control method implemented by a controller according to another exemplary embodiment of the present application. As shown in Figure 7, after the input voltage of the buck circuit rises to the second voltage threshold, the controller stops adjusting the duty cycle of the driving signal and is further used to perform the following step S701.

Step S701, obtaining the output voltage of the buck circuit, and when the duration during which the output voltage does not change reaches a preset duration threshold, increasing the duty cycle of the buck circuit drive signal by using a third deviation adjustment algorithm.

When the duration of no change in the output voltage of the buck circuit reaches a preset duration threshold, it means that the heating unit has been working at a stable heating power for at least the preset duration, indicating that the input power provided by the power supply has been stable and the heating unit has been working stably at a certain power. Then, the duty cycle of the driving signal can be adjusted again to restore the output voltage of the buck circuit to the first preset voltage.

It can be understood that the fact that the output voltage of the buck circuit has not changed means that the fluctuation of its output voltage is within a preset range. For example, if the output voltage fluctuates within 0.1V, it can be considered that there is no change.

It can be understood that the third deviation adjustment algorithm can be the same as the first deviation adjustment algorithm, both of which stabilize the buck circuit output at the first preset voltage through deviation adjustment.

It can be understood that if it is found again during the adjustment process that the buck circuit input voltage drops to the first voltage threshold, the above steps S601 to S602 are repeatedly executed to increase the input voltage.

It can be understood that the specific value of the preset duration threshold can be set according to actual needs, for example, 1 minute, 2 minutes, etc. are not limited here.

The above technical solution adjusts the duty cycle of the buck circuit again to increase its heating power after the heating unit has worked continuously for at least a preset time with a stable heating power, so that efficient heating can be achieved after the power supply is restored.

Please refer to FIG8, which is a flowchart of the steps of controlling the heating unit to stop working in the battery pack heating control method of the present application in an exemplary embodiment. As shown in FIG8, based on the above embodiment, the battery pack heating control method may also include steps S801 to S803. The above steps are used to determine whether the battery pack meets the pre-set exit heating conditions, which are described in detail as follows.

Step S801, obtaining the temperature of the battery pack.

When the battery cell is used, the temperature of the battery pack is obtained in real time. It is understood that here, the temperature of the battery pack can be obtained directly by detecting the temperature of the entire battery cell. For example, a temperature sensor is set on the battery pack to detect the overall temperature of the battery pack. The temperature of the battery pack can also be obtained by detecting the temperature of each battery cell in the battery cell separately and calculating the average value, or the temperature of the battery cell with the highest temperature is used as the battery pack temperature. This application does not limit this.

Step S802 , if the temperature of the battery pack is greater than the second preset temperature, the voltage reduction unit is controlled to stop outputting the output voltage to the heating unit.

Among them, the second preset temperature is greater than the first preset temperature. In this embodiment, the second preset temperature can be regarded as the temperature condition for the battery unit to resume normal charging, that is, the temperature of the battery pack is raised to a temperature exceeding the second preset temperature by heating the heating unit or increasing the ambient temperature. At this temperature, the battery pack can be charged and discharged normally. In this embodiment, the second preset temperature can be set to 10 degrees Celsius, or a temperature value greater than 10, as long as it meets the temperature threshold condition that can reflect the restoration of normal charging of the battery, and no specific limitation is made here.

Step S803, when the temperature difference between any two battery cells is greater than the temperature difference threshold, the voltage reduction unit is controlled to stop outputting voltage to the heating unit.

As mentioned above, the battery unit of the battery pack includes multiple battery cells. Heating the battery pack by the heating unit is the heating of multiple battery cells. When it is detected that the temperature difference between any two battery cells is greater than the temperature difference threshold, it means that the battery cells are heated unevenly or the battery cells are faulty. Regardless of the reason for the temperature difference, continuing to heat the battery cells and using multiple battery cells will pose a safety hazard, so the step-down unit is controlled to stop output, that is, the heating unit is controlled to stop working.

It should be noted that there is no temporal order relationship between step S802 and step S803. As long as at least one of the above-mentioned conditions for exiting heating is met at any time, the heating unit can be controlled to stop working.

In this way, this embodiment obtains the temperature of the battery pack and multiple battery cells in the battery pack in real time, and determines whether the obtained temperature of the battery pack or multiple battery cells meets the conditions for exiting heating based on the second preset temperature and the temperature difference threshold. When the conditions for exiting heating are met, the heating unit is immediately controlled to stop working, saving resources and avoiding battery damage.

Please refer to FIG. 9, which is a flowchart of the steps of controlling the heating unit to stop working in the battery pack heating control method of the present application in an exemplary embodiment. As shown in FIG. 9, based on the above embodiment, the battery pack heating control method may also include steps S901 to S903. The above steps are used to determine whether the battery pack meets the pre-set exit heating conditions, which are described in detail as follows.

Step S901, when the heating unit is working, counting the working time of the heating unit and determining the working state of the heating unit.

When the heating unit is controlled to start working, the working time of the heating unit is counted, and the real-time working status of the heating unit is determined, wherein the working status includes normal heating and heating failure.

Step S902: When the working time is longer than the preset heating time, the heating unit is controlled to stop working.

When the working time is longer than the preset heating time, it means that the temperature of the battery pack has not reached the temperature required for normal charging at normal temperature through the heating of the heating unit within the preset heating time, and continuing to control the heating unit to work will cause a waste of resources and costs, so the heating unit is controlled to stop working.

Step S903, when the working state is heating failure, control the heating unit to stop working.

When the working state of the heating unit is a heating failure, for example, the heating unit itself has poor contact or the device is damaged and cannot work, it means that the heating unit is no longer suitable to continue working. Continuing to work will result in poor heating effect or even safety hazards, so the heating unit is controlled to stop working.

It should be noted that the statistics of working time and the confirmation of the working status of the heating unit in step S901 are started and continued at the same time, so there is no time sequence between step S902 and step S903. At any time when the heating unit is controlled to work, as long as at least one of the conditions for exiting heating is met, the heating unit can be controlled to stop working.

In this way, after controlling the heating unit to start working, this embodiment determines whether the heating unit meets the conditions for exiting heating based on the working time and working status of the heating unit, and immediately controls the heating unit to stop working when the conditions for exiting heating are met.

An embodiment of the present application also provides an electronic device, comprising: one or more processors; a battery pack; and a storage device for storing one or more programs. When the one or more programs are executed by one or more processors, the electronic device implements the battery pack heating control method provided in the above-mentioned embodiments.

It can be understood that the above-mentioned electronic device can be an independent battery pack, and the battery pack can form an energy storage system with the power supply shown in Figure 2 or Figure 3. The above-mentioned electronic device can also be any energy storage device including a battery pack, and the device has a power conversion device integrated inside. The energy storage device can form a microgrid system with an external power supply such as an AC power supply or a DC power supply. The present application does not limit the product form of the electronic device. Any device that includes or requires a suitable battery can implement the battery pack heating control method in the above-mentioned embodiments through an internally integrated or externally connected processor.

Fig. 10 shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiment of the present application. It should be noted that the computer system 1000 of the electronic device shown in Fig. 10 is only an example and should not bring any limitation to the function and scope of use of the embodiment of the present application.

As shown in FIG. 10 , the computer system 1000 includes a central processing unit (CPU) 1001, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 1002 or the program loaded from the storage part 1008 to the random access memory (RAM) 1003, such as executing the method in the above embodiment. In the RAM 1003, various programs and data required for system operation are also stored. The CPU 1001, the ROM 1002, and the RAM 1003 are connected to each other through the bus 1004. The input/output (I/O) interface 1005 is also connected to the bus 1004.

The following components are connected to the I/O interface 1005: an input section 1006 including a keyboard, a mouse, etc.; an output section 1007 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1008 including a hard disk, etc.; and a communication section 1009 including a network interface card such as a LAN (Local Area Network) card, a modem, etc. The communication section 1009 performs communication processing via a network such as the Internet. A drive 1010 is also connected to the I/O interface 1005 as needed. A removable medium 1011, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 1010 as needed so that a computer program read therefrom is installed into the storage section 1008 as needed.

In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication part 1009, and/or installed from a removable medium 1011. When the computer program is executed by a central processing unit (CPU) 1001, various functions defined in the system of the present application are executed.

It should be noted that the computer-readable medium shown in the embodiment of the present application may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable computer program. This propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. A computer program contained on a computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present application. Among them, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the above-mentioned module, a program segment or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

The units involved in the embodiments described in this application may be implemented by software or hardware, and the units described may also be set in a processor. The names of these units do not, in some cases, constitute limitations on the units themselves.

Another aspect of the present application further provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the battery pack heating control method as described above is implemented. The computer-readable storage medium may be included in the electronic device described in the above embodiment, or may exist independently without being assembled into the electronic device.

Another aspect of the present application also provides a computer program product or a computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device executes the battery pack heating control method provided in each of the above embodiments.

The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (10)

1. A battery pack, comprising a switch unit, a battery unit, a heating unit, a voltage reduction unit, an interface unit and a controller;

   The interface unit is used to connect to a power supply;

   The battery unit is used to connect to the interface unit via the switch unit;

   Two ends of the heating unit are connected in parallel to the output end of the voltage reduction unit;

   The input end of the step-down unit is connected to the interface unit, and the step-down unit is used to convert the input voltage of the power supply into an output voltage and output it to the heating unit;

   The heating unit is used to heat the battery pack under the control of the output voltage;

   The controller is used to:

   When the temperature of the battery pack is lower than a first preset temperature, obtaining a connection state of the power supply and an on/off state of the switch unit;

   When the power supply is connected and the switch unit is in an off state, controlling the output voltage of the voltage reduction unit to remain at a first preset voltage;

   When the input voltage of the buck unit is less than or equal to a first voltage threshold, the output voltage of the buck unit is controlled to decrease from the first preset voltage until the input voltage of the buck unit is greater than or equal to a second voltage threshold; the second voltage threshold is greater than the first voltage threshold, and the second voltage threshold is greater than the reference voltage of the battery pack.
2. The battery pack according to claim 1, wherein the controller is further configured to:

   When the temperature of the battery pack is lower than the first preset temperature, the switch unit is controlled to be turned off.
3. The battery pack according to claim 2, wherein the controller is used to obtain the on/off state of the switch unit, comprising:

   Monitoring the real-time discharge current value of the battery unit;

   If it is detected that the real-time discharge current value is less than or equal to the preset current threshold, it is determined that the switch unit is in the off state.
4. The battery pack according to claim 3, wherein the step-down unit comprises a buck circuit; and the controller is used to control the output voltage of the step-down unit to remain at a first preset voltage, comprising:

   Obtaining the output voltage of the buck circuit;

   Adjusting the duty cycle of the driving signal based on the first preset voltage, the output voltage of the buck circuit and a first deviation adjustment algorithm;

   The buck circuit is driven by the adjusted driving signal so that the buck circuit outputs the first preset voltage.
5. The battery pack according to claim 1, wherein the step-down unit comprises a buck circuit; and the controller is used to control the output voltage of the step-down unit to decrease from the first preset voltage until the input voltage of the step-down unit rises to a second voltage threshold, comprising:

   Based on the first voltage threshold, the input voltage of the buck circuit and the second deviation adjustment algorithm, the duty cycle of the driving signal is adjusted, wherein the duty cycle of the driving signal after the adjustment is less than the duty cycle before the adjustment;

   The buck circuit is driven according to the adjusted driving signal, and the duty cycle of the driving signal is stopped from being adjusted after the input voltage of the buck circuit rises to a second voltage threshold.
6. The battery pack according to claim 5, wherein, after controlling the output voltage of the step-down unit to rise to the second voltage threshold, the controller is further configured to:

   The output voltage of the buck circuit is obtained, and when the duration during which the output voltage of the buck circuit does not change reaches a preset duration threshold, the duty cycle of the buck circuit driving signal is increased by a third deviation adjustment algorithm.
7. The battery pack according to claim 1, wherein the controller is further configured to:

   Acquiring the temperature of the battery pack;

   If the temperature of the battery pack is greater than a second preset temperature, the voltage reduction unit is controlled to stop outputting the output voltage to the heating unit.
8. The battery pack according to any one of claims 1 to 6, wherein the controller is further used for:

   Acquire the reference voltage of the battery pack, where the reference voltage value is greater than the first voltage threshold and less than a second voltage threshold;

   When the input voltage of the step-down unit is less than the reference voltage, the switch unit is controlled to be turned on.
9. A method for controlling heating of a battery pack, the battery pack comprising a switch unit, a battery unit, a heating unit, a voltage reduction unit and an interface unit; the interface unit is used to connect to a power supply; the battery unit is used to connect to the interface unit via the switch unit; both ends of the heating unit are connected in parallel to the output end of the voltage reduction unit; the input end of the voltage reduction unit is connected to the interface unit; the method comprises:

   When the temperature of the battery pack is lower than a first preset temperature, obtaining a connection state of the power supply and an on/off state of the switch unit;

   When the power supply is connected and the switch unit is in an off state, controlling the output voltage of the voltage reduction unit to remain at a first preset voltage;

   When the input voltage of the buck unit is less than or equal to a first voltage threshold, the output voltage of the buck unit is controlled to decrease from the first preset voltage until the input voltage of the buck unit is greater than or equal to a second voltage threshold; the second voltage threshold is greater than the first voltage threshold, and the second voltage threshold is greater than the reference voltage of the battery pack.
10. An electronic device, comprising:

    one or more processors;

    The battery pack according to any one of claims 1 to 8;

    A storage device for storing one or more programs, which, when executed by the one or more processors, enables the electronic device to implement the battery pack heating control method as described in claim 9.

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