Battery pack, control method, power utilization device, readable storage medium and vehicle

Abstract

The invention discloses a battery pack, a control method, a power utilization device, a readable storage medium and a vehicle, and relates to the technical field of batteries. The battery pack comprises a control unit, a first battery pack, a voltage converter and a second battery pack, the first battery pack is connected with the first end of the voltage converter; the second battery pack is connected with the second end of the voltage converter and is connected with the load so as to supply power to the load; the control unit is connected with the first battery pack, the voltage converter and the second battery pack and used for controlling the voltage converter to convert the voltage output by the first battery pack and output the first charging voltage to the second battery pack. Since the power supply voltage of the load is guaranteed by the second battery pack, the discharge of the first battery pack is not restricted by the power supply voltage of the load, and the first battery pack can realize full discharge, so that the first battery pack can have higher electric quantity utilization rate, and the electric quantity utilization rate of the whole battery pack can be improved.

Description

Battery pack, control method, power-consuming device, readable storage medium, and vehicle Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery pack, a control method, an electrical device, a readable storage medium, and a vehicle. Background Art

[0002] Currently, to improve the convenience and reduce the cost of using electrical devices, secondary batteries are often used to power the loads in these devices. When using batteries to power loads, the battery output voltage must match the voltage required by the load. If the battery output voltage is lower than the load's required voltage, the load will operate at a low voltage, potentially damaging the load or preventing it from fully performing.

[0003] The battery's output voltage is related to the remaining charge. The less charge remaining in the battery, the lower the output voltage. When the battery's output voltage is lower than the voltage required by the load, the load must stop operating and the battery must stop discharging to prevent it from operating at low voltage.

[0004] In the related art, when some batteries have a large amount of remaining power, the output voltage is lower than the voltage required by the load and cannot power the load. Such batteries will have a large amount of remaining power each time they are discharged, and the power utilization rate is low.

[0005] Application Contents

[0006] The purpose of the embodiments of the present application is to provide a battery pack, a control method, an electrical device, a readable storage medium and a vehicle, including but not limited to solving the problem of low battery power utilization.

[0007] In a first aspect, a battery pack is provided, comprising a control unit, a first battery pack, a voltage converter, and a second battery pack;

[0008] The first battery pack is connected to the first end of the voltage converter;

[0009] The second battery pack is connected to the second end of the voltage converter, and the second battery pack is connected to a load;

[0010] The control unit is connected to the first battery pack, the voltage converter and the second battery pack respectively, and is used to control the voltage converter to convert the voltage output by the first battery pack and output a first charging voltage to the second battery pack.

[0011] The beneficial effect of the battery pack provided by the embodiment of the present application is that: the battery pack includes a first battery group and a second battery group. In the process of supplying power to the load, the second battery group directly supplies power to the load, and the second battery group guarantees the supply voltage of the load. At the same time, the first battery group charges the second battery group through a voltage converter to indirectly supply power to the load, thereby achieving decoupling of the first battery group and the load. Since the supply voltage of the load is guaranteed by the second battery group, the discharge of the first battery group is not restricted by the supply voltage of the load. The remaining power of the first battery group during the power supply process can drop to the minimum value to achieve full discharge, so that the first battery group can have a higher power utilization rate, thereby improving the power utilization rate of the entire battery pack.

[0012] Moreover, since the power utilization rate of the battery pack is improved, the battery pack can supply power to the load for a longer time after each charge of the battery pack, which can reduce the charging frequency of the battery pack.

[0013] In some embodiments, the charge of the first battery pack is greater than or equal to the charge of the second battery pack.

[0014] In the embodiment of the present application, setting the power of the first battery group to be greater than the power of the second battery group can increase the proportion of the power of the first battery group in the total power of the battery pack, thereby making the battery pack have a higher power utilization rate.

[0015] In some embodiments, the power of the first battery pack is M times that of the second battery pack, where M is greater than or equal to 1 and less than or equal to 10.

[0016] In some embodiments, the voltage converter is a bidirectional voltage converter; the control unit is also used to control the voltage converter to convert the recovery voltage and output a second charging voltage to the first battery pack when the load outputs the recovery voltage to the second battery pack.

[0017] In an embodiment of the present application, when the voltage converter is a bidirectional voltage converter, the control unit can control the voltage converter to convert the recovery voltage of the load input to the second battery group, and input the charging voltage to the first battery group, so that the electricity fed back by the load can be recovered through the first battery group.

[0018] In some embodiments, the battery pack includes a plurality of first battery groups, and each of the first battery groups is connected to the first end of the voltage converter.

[0019] In an embodiment of the present application, when the battery pack includes multiple first battery groups, the multiple first battery groups can provide voltage to the voltage converter in turn to provide a stable first charging voltage to the second battery group.

[0020] In some embodiments, the battery pack includes a plurality of second battery groups, and each second battery group is connected to the second end of the voltage converter.

[0021] In an embodiment of the present application, when the battery pack includes multiple second battery packs, any one of the multiple second battery packs can be used to power the load, and at the same time, the control unit can conveniently charge any one of the multiple second battery packs separately through the first battery pack.

[0022] In some embodiments, the first battery pack is assembled from a plurality of sodium-ion single cells.

[0023] In the embodiment of the present application, the first battery pack is assembled from a plurality of sodium-ion single cells. Since the cost of sodium-ion batteries is relatively low, the cost of the entire battery pack can be reduced.

[0024] In some embodiments, the second battery pack is assembled from a plurality of sodium-ion single batteries or a plurality of lithium-ion single batteries.

[0025] In a second aspect, a control method is provided. The method is applied to a control unit in a battery pack. The battery pack further includes a first battery pack, a second battery pack, and a voltage converter. The first battery pack is connected to a first end of the voltage converter, the second battery pack is connected to a second end of the voltage converter, and the second battery pack is connected to a load. The control unit is connected to the first battery pack, the voltage converter, and the second battery pack, respectively. The method includes:

[0026] The control unit controls the voltage converter to convert the voltage output from the first battery pack and output a first charging voltage to the second battery pack.

[0027] In a third aspect, an electrical device is provided, wherein the electrical device includes the battery pack as described in the first aspect.

[0028] In a fourth aspect, a readable storage medium is provided, wherein the readable storage medium is used to store computer program code. When the computer program code is executed by a control unit in a battery pack, the control unit executes the method described in the second aspect.

[0029] In a fifth aspect, a vehicle is provided, comprising the battery pack as described in the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings described 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 any creative work.

[0031] FIG1 is a schematic diagram of voltage variation of a battery provided in an embodiment of the present application.

[0032] FIG2 is a schematic diagram of a power supply principle of an electrical device provided in an embodiment of the present application.

[0033] FIG3 is a schematic diagram of a power supply principle of another electrical device provided in an embodiment of the present application.

[0034] FIG4 is a schematic diagram of a power supply principle of another electrical device provided in an embodiment of the present application.

[0035] FIG5 is a schematic diagram of the circuit principle of a battery pack provided in an embodiment of the present application.

[0036] FIG6 is a schematic diagram of voltage changes of a first battery pack provided in an embodiment of the present application.

[0037] FIG7 is a schematic diagram of voltage changes of a second battery pack provided in an embodiment of the present application.

[0038] FIG8 is a schematic diagram of a power supply principle of another electrical device provided in an embodiment of the present application.

[0039] FIG9 is a schematic diagram of a power supply principle of another electrical device provided in an embodiment of the present application.

[0040] FIG10 is a schematic diagram of a power supply principle of another electrical device provided in an embodiment of the present application.

[0041] FIG11 is a flowchart of the steps of a control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the accompanying drawings are intended to cover non-exclusive inclusions.

[0044] In the description of the embodiments of this application, the terms "first," "second," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0045] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated 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 simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0046] To improve the convenience and reduce the cost of using electrical devices, secondary batteries (hereinafter referred to as batteries) are often installed in these devices to power the loads within them. Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after discharge to activate the active materials within the battery and continue to power the load.

[0047] When a battery is used to power a load, the battery's output voltage must match the load's required supply voltage. The output voltage is the voltage between the battery's positive and negative terminals during discharge, while the supply voltage is the voltage applied to the load. To prevent the load from operating at low voltage, the load must be disconnected and the battery must stop discharging when the battery's output voltage falls below the load's supply voltage.

[0048] During the use of electrical devices, in order to avoid frequent battery charging, the power in the battery must be used to power the load as much as possible. The higher the power utilization rate, the longer the battery can power the load after each charge, and the lower the battery charging frequency.

[0049] After each charge, the battery's output voltage changes with the battery's state of charge (SOC). SOC represents the ratio of the remaining charge in the battery to the total battery capacity, and also indicates the amount of remaining charge in the battery. The less charge remaining in the battery, the lower the battery's output voltage. Different types of batteries have different trends in how their output voltage changes with SOC.

[0050] The following uses the voltage variation trends of lithium-ion batteries and sodium-ion batteries as examples to illustrate the variation process of the battery's output voltage.

[0051] Figure 1 is a schematic diagram of voltage variation of a battery provided by an embodiment of the present application. In Figure 1 , the horizontal axis represents the battery's state of charge, the vertical axis represents the battery's output voltage, curve 11 represents the voltage variation curve for a lithium-ion battery, and curve 12 represents the voltage variation curve for a sodium-ion battery.

[0052] As shown in Figure 1, when a lithium-ion battery is fully charged, its charge reaches its maximum. At this point, the battery's SOC is 100%, and its output voltage reaches its maximum value, VH1. As it supplies power to a load, the remaining charge in the battery decreases, and its output voltage gradually decreases. When the remaining charge drops to 5%, the output voltage drops to VL1. Furthermore, when the remaining charge in the battery drops beyond 5%, the output voltage drops sharply, rendering it unable to supply power to the load. This 5% remaining charge is referred to as the lithium-ion battery's discharge cutoff capacity. This capacity is the remaining charge in the battery when its output voltage approaches or equals the load's supply voltage during discharge. This capacity value can also be referred to by other names.

[0053] Similarly, when a sodium-ion battery is fully charged, the amount of charge in the battery reaches its maximum, and the output voltage of the battery reaches its maximum value, VH2. As the battery supplies power to a load, the remaining charge in the battery decreases, and the output voltage gradually decreases. When the remaining charge drops to 30%, the output voltage of the battery drops to VL1. When the remaining charge in the battery drops beyond 30%, the output voltage drops sharply, and the battery is unable to supply power to the load. As shown in Figure 1, the discharge cutoff capacity of the sodium-ion battery is 30%.

[0054] As shown in Figure 1, although the sodium-ion battery can no longer power the load after its remaining charge drops to 30%, it can still continue to discharge. When the remaining charge of the sodium-ion battery drops to the lower limit, the sodium-ion battery needs to be charged. The lower limit is the minimum amount of charge that can remain in the battery during discharge. The lower limit of the sodium-ion battery's charge can be close to or equal to 5% of the sodium-ion battery's charge.

[0055] It should be noted that FIG1 is only an example. In actual applications, the discharge cut-off capacity of lithium-ion batteries is close to or equal to 5%, and the discharge cut-off capacity of sodium-ion batteries is close to or equal to 30%. There are certain differences in the discharge cut-off capacity of batteries of the same type.

[0056] Typically, the lower limit of the load's required supply voltage is VL1. When a lithium-ion battery is used to power the load, the battery's output voltage matches the load's required supply voltage until the remaining charge drops to 5%, allowing the load to continue to be powered. When the remaining charge drops to 5%, the load must cease operation, and the lithium-ion battery stops discharging. Understandably, a lithium-ion battery retains a 5% remaining charge during each discharge. This 5% remaining charge represents a relatively small portion of the battery's total capacity, resulting in a relatively high power utilization rate.

[0057] When sodium-ion batteries are used to power loads, if the remaining charge drops to 30%, the battery can no longer supply power to the load and must stop supplying power. Only after the battery is recharged can it supply power to the load again. Understandably, each time a sodium-ion battery discharges, 30% of its charge remains. This 30% remaining charge accounts for a significant portion of the battery's total charge, resulting in low power utilization.

[0058] Due to the low power utilization rate, during the charging and discharging process of the sodium-ion battery, the sodium-ion battery needs to be charged again when the remaining power drops to 30%, resulting in a high charging frequency of the sodium-ion battery during use.

[0059] It should be noted that batteries with low power utilization include but are not limited to sodium-ion batteries, and may also be other batteries similar to sodium-ion batteries.

[0060] To address the technical issue of low power utilization in sodium-ion batteries and other similar battery types, one alternative approach is to redesign the loads in the electrical device. Figure 2 is a schematic diagram of the power supply principle of an electrical device provided in an embodiment of the present application. The electrical device includes a battery and multiple loads, and may also include other components, which are not limited in this embodiment.

[0061] The battery shown in Figure 2 is, for example, a sodium-ion battery or other similar battery. Each load in Figure 2 has a relatively wide supply voltage range. As shown in Figure 1, the maximum supply voltage to the load can reach VH2, and the minimum can reach VL2. In this case, the sodium-ion battery can continue to power the load even after the remaining charge drops to 30%. During the power supply process, the remaining charge of the sodium-ion battery can drop to 5%, resulting in a high power utilization rate.

[0062] While the approach shown in Figure 2 can address the issue of low power utilization, it requires redesigning each load in the electrical device, and the loads' supply voltage range is relatively wide. This wide range of load supply voltages increases design complexity, design cycles, and design costs. Furthermore, redesigning loads to accommodate a specific battery type is not practically feasible.

[0063] To address the technical issue of low battery power utilization, another approach is to install a voltage converter between the battery and the load. Figure 3 is a schematic diagram of the power supply principle of another power-consuming device provided in an embodiment of the present application. The power-consuming device includes a battery, a voltage converter, and multiple loads. Other components may also be included, which are not limited in this embodiment.

[0064] In the electrical device shown in Figure 3, the input of the voltage converter is connected to the battery, and the output is connected to each load. The voltage converter has a wide input voltage range, with a maximum value of VH2 (shown in Figure 1) and a minimum value of VL2. When the battery is a sodium-ion battery or other similar battery, the voltage converter converts the battery's output voltage to obtain and output the supply voltage to each load. Due to the wide input voltage range of the voltage converter, the remaining battery charge can be reduced to 5% during the load power supply process, resulting in high power utilization.

[0065] While the method shown in Figure 3 can address the issue of low power utilization, the voltage converter must be adapted to the load. When the load's power is high, the voltage converter must be a high-power converter. Furthermore, to meet the load's power demands during peak operating conditions, the voltage converter must have a high level of redundancy.

[0066] For example, when the power consumer is an electric vehicle, the loads include high-power loads such as heat pumps, air conditioning compressors, and electric drive systems. In this case, a high-power voltage converter is required for the battery to meet the loads' power demands. Furthermore, because the peak power of each load is higher than its rated power, the voltage converter's power needs to be higher than the rated power of each load. Typically, the voltage converter's power is three times the rated power of the load.

[0067] It is understandable that in the method shown in Figure 3, the greater the power of the load, the greater the power of the voltage converter. However, high-power voltage converters are more expensive, consume more power during use, and have poor reliability.

[0068] The electrical devices mentioned in the above examples may include, but are not limited to, mobile phones, tablets, laptop computers, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0069] It should be noted that the battery in an electrical device can be a single cell (battery cell) or a battery pack composed of multiple cells connected in series and / or in parallel. When the load in the electrical device is a low-voltage load, the battery can be a single cell; when the load in the electrical device is a high-voltage load, the battery can be a battery pack. The output voltage of a single cell varies with the remaining charge in the cell. Similarly, the output voltage of a battery pack composed of multiple cells will also vary with the remaining charge in the pack.

[0070] In order to solve the problem of low power utilization, an embodiment of the present application provides a battery pack, which includes a control unit, a first battery pack, a voltage converter, and a second battery pack. In the process of supplying power to the load, the second battery pack is connected to the load to supply power to the load and provide a stable power supply voltage for the load. The control unit controls the voltage converter to convert the output voltage of the first battery pack, and outputs a charging voltage to the second battery pack to charge the second battery pack, so as to indirectly supply power to the load, thereby realizing the decoupling of the first battery pack and the load. The power supply voltage of the load is guaranteed by the second battery pack, so the discharge of the first battery pack is not restricted by the power supply voltage of the load, and the remaining power of the first battery pack during the power supply process can be reduced to the minimum value to fully discharge, so that the first battery pack has a higher power utilization rate, thereby improving the power utilization rate of the entire battery pack.

[0071] In the present application, the battery pack includes a control unit, a first battery group, a voltage converter and a second battery group; the first battery group is connected to the first end of the voltage converter; the second battery group is connected to the second end of the voltage converter, and the second battery group is connected to the load; the control unit is respectively connected to the first battery group, the voltage converter and the second battery group, and is used to control the voltage converter to convert the voltage output by the first battery group and output the first charging voltage to the second battery group.

[0072] To facilitate understanding of the technical solutions in the embodiments of the present application, the composition and principle of the battery pack are exemplarily explained below using the application of the battery pack in an electric vehicle as an example.

[0073] Figure 4 is a schematic diagram of the power supply principle of another electrical device provided in an embodiment of the present application. The electric vehicle includes a battery pack for powering the entire electric vehicle. The battery pack includes a first battery pack, a voltage converter, a second battery pack, and a control unit. The electric vehicle includes multiple loads, including, but not limited to, a heat pump, an air conditioning compressor, and an electric drive system. The electric vehicle may also include other components, which are not detailed in this embodiment.

[0074] In some embodiments, the first battery pack may include one or more battery modules, each of which is composed of multiple single cells connected in series and / or in parallel. When the first battery pack includes multiple battery modules, the multiple battery modules may be connected in series and / or in parallel. Similarly, the second battery pack may include one or more battery modules, each of which is composed of multiple single cells connected in series and / or in parallel. When the second battery pack includes multiple battery modules, the multiple battery modules may be connected in series and / or in parallel.

[0075] In some embodiments, the voltage converter is a unidirectional direct current to direct current converter (DC / DC). The first end of the voltage converter is an input end, and the second end is an output end, the input end includes a positive input end and a negative input end, and the output end includes a positive output end and a negative output end.

[0076] For example, when the output voltage of the first battery pack is lower than the input voltage of the second battery pack, the DC-DC converter may be a DC boost circuit that can boost the output voltage of the first battery pack to obtain and output a first charging voltage to the second battery pack. When the output voltage of the first battery pack is higher than the input voltage of the second battery pack, the DC-DC converter may be a DC buck circuit that can buck the output voltage of the first battery pack to obtain and output the first charging voltage to the second battery pack. Specific types of voltage converters may include, but are not limited to, the above examples.

[0077] Figure 5 is a schematic diagram of the circuit principles of a battery pack provided in an embodiment of the present application. A first battery pack 51 includes a battery module 511 and a cell monitoring unit (CMU) 512 corresponding to the battery module 511. The CMU 512 is configured to monitor parameters such as the voltage, current, and temperature of the battery module 511, but is not limited thereto.

[0078] The positive terminal (P+) of the first battery pack 51 can be led outward through a wire, and the negative terminal (P-) of the first battery pack 51 can be led outward through a wire. The positive terminal is connected to the positive input terminal of the first terminal 531 of the voltage converter 53, and the negative terminal is connected to the negative input terminal of the first terminal 531 of the voltage converter 53.

[0079] The first battery pack 51 may further include a current sensor 513 . The current sensor 513 is disposed in the charge and discharge circuit of the first battery pack 51 and is used to monitor the current of the first battery pack 51 during the charge and discharge process.

[0080] Among them, the charging and discharging circuit can be understood as a circuit through which current flows during the charging and discharging process. The charging and discharging circuit of the first battery group 51 is a circuit that passes through the positive end of the first battery group 51, the battery module 511, the current sensor 513, the negative end of the first battery group 51, and finally returns to the positive end of the first battery group 51.

[0081] In practical applications, the first battery pack 51 may include multiple battery modules 511 and a battery monitoring unit 512 corresponding to each battery module 511. When the first battery pack 51 includes multiple battery modules 511, the multiple battery modules 511 may be connected in series and / or in parallel. The first battery pack 51 may also include other components as needed, which are not limited in this embodiment.

[0082] Similarly, the second battery pack 52 includes a battery module 521, a battery monitoring unit 522 corresponding to the battery module 521, and a current sensor 523 disposed in the charge and discharge circuit of the second battery pack 52. The circuit structure of the second battery pack 52 is the same as that of the first battery pack 51 and is not further described in this embodiment.

[0083] As shown in FIG5 , the positive terminal of the second battery pack 52 is connected to the positive terminal of the load 55, and the positive terminal of the second battery pack 52 is connected to the positive output terminal of the voltage converter 53. The negative terminal of the second battery pack 52 is connected to the negative terminal of the load 55, and can supply power to the load 55. The negative terminal of the second battery pack 52 is also connected to the negative output terminal of the voltage converter 53. The load 55 is the various loads shown in FIG4 , including the electric drive system, the air conditioning compressor, and the heat pump.

[0084] In an electric vehicle, the control unit may be a battery management system (BMS) 54. As shown in FIG5 , the BMS is connected to a current sensor 513, which can be used to collect the current value in the charge and discharge circuit of the first battery pack 51. Similarly, the BMS is connected to a current sensor 523, which can be used to collect the current value in the charge and discharge circuit of the second battery pack 52.

[0085] It should be noted that in other electrical devices, the control unit may be another circuit module with control functions. For example, when the electrical device is a power tool, the power tool includes an integrated circuit board for controlling the operation of the power tool, and the control unit may be a battery management module integrated on the integrated circuit board. For another example, when the electrical device is an electric toy, the electric toy includes a control circuit for controlling the operation of the electric toy, and the functions of the control unit are implemented by a processor integrated in the control circuit. In this case, the control circuit is the control unit. The specific implementation of the control unit in different electrical devices may include, but is not limited to, the examples above, and this embodiment does not limit this.

[0086] Taking the voltage converter 53 as a unidirectional voltage converter as an example, the positive terminal of the first battery pack 51 is connected to the positive input terminal of the first terminal 531 of the voltage converter 53, and the negative terminal is connected to the negative input terminal of the first terminal 531 of the voltage converter 53. Simultaneously, the positive terminal of the second battery pack 52 is connected to the positive output terminal of the second terminal 532 of the voltage converter 53, and the negative terminal is connected to the negative output terminal of the second terminal 532 of the voltage converter 53. After startup, the voltage converter 53 can convert the output voltage of the first battery pack 51 and output a voltage to the second battery pack 52. This voltage can be referred to as a first charging voltage.

[0087] In this embodiment, during the process of charging the battery pack, the first battery pack and the second battery pack may be charged simultaneously, or the first battery pack may be charged first and then the second battery pack.

[0088] As shown in FIG5 , in some embodiments, the BMS includes a charging management module, which is connected to the onboard charger of the electric vehicle. During the charging process, the charging management module first controls the onboard charger to connect to the positive and negative terminals of the first battery pack 51 to charge the first battery pack 51. After the first battery pack 51 is fully charged, the charging management module controls the onboard charger to disconnect from the first battery pack 51 and then controls the onboard charger to connect to the positive and negative terminals of the second battery pack 52 to charge the second battery pack 52. After the second battery pack is fully charged, charging ends.

[0089] In other embodiments, during the charging process, the charging management module controls the onboard charger to connect to the first battery pack 51. After detecting that the onboard charger is charging the first battery pack 51 and the first battery pack 51 is fully charged, the BMS can control the voltage converter 53 to start operating. After starting operation, the voltage converter 53 converts the output voltage of the first battery pack 51 to obtain and output a charging voltage to the second battery pack 52 to charge the second battery pack 52. In this case, the output voltage of the first battery pack 51 is the voltage input by the onboard charger to the positive and negative terminals of the first battery pack 51.

[0090] The above examples are merely illustrative and do not limit the charging method of the battery pack. The charging method of the first battery pack 51 and the second battery pack 52 may include but is not limited to the above examples.

[0091] In this embodiment, during the process of supplying power to the load through the battery pack, the second battery pack directly supplies power to the load, and the control unit can control the voltage converter to start at a corresponding time point to charge the second battery pack.

[0092] In some embodiments, the BMS is in communication with the vehicle control unit (VCU) in the electric vehicle. After the electric vehicle is started, the VCU can control the BMS to start running. In the first control method of the battery pack, after the BMS starts running, it directly controls the voltage converter to start.

[0093] As shown in Figure 5, the output voltage of the first battery group 51 is input to the input end of the voltage converter 53. After starting up, the voltage converter 53 can convert the output voltage of the first battery group 51 to obtain a converted voltage, which is the first charging voltage. The first charging voltage is input to the positive and negative terminals of the second battery group 52.

[0094] The voltage converter 53 can control the magnitude of the first charging voltage based on the output voltage of the second battery pack 52, so that the first charging voltage is within a reasonable voltage range. When the first charging voltage is within the reasonable voltage range, the first charging voltage is greater than the output voltage of the second battery pack 52, and the second battery pack 52 can be charged without damaging the second battery pack 52. The specific method for controlling the voltage converter 53 to output the first charging voltage can be set as required and is not limited in this embodiment.

[0095] It is understood that when the first charging voltage is input to the positive and negative terminals of the second battery pack 52, the current in the charge-discharge circuit of the second battery pack 52 maintains a dynamic balance. As shown in Figure 5, when the first charging voltage is input to the positive and negative terminals of the second battery pack 52, if the current required by the load 55 is greater than the current provided by the first charging voltage, the first charging voltage and the output voltage of the second battery pack 52 simultaneously input current into the charge-discharge circuit of the second battery pack 52 to provide current to the load 55 and meet the load's power demand. At this point, it is equivalent to the voltage converter 53 and the second battery pack 52 simultaneously supplying power to the load 55, that is, the first battery pack 51 and the second battery pack 52 simultaneously supply power to the load 55.

[0096] If the current required by the load 55 is less than the current provided by the first charging voltage, part of the current input by the first charging voltage into the charging and discharging circuit of the second battery group 52 is transmitted to the load 55 to power the load 55, and the other part is input into the second battery group 52 to charge the second battery group 52. At this time, the first battery group 51 charges the second battery group 52 through the voltage converter 53 and supplies power to the load 55.

[0097] If the current required by the load 55 is equal to the current provided by the first charging voltage, the current input by the first charging voltage into the charge and discharge circuit of the second battery pack 52 is transmitted to the load 55 to supply power to the load 55. At this time, the first battery pack 51 alone supplies power to the load 55 through the voltage converter 53, and the remaining power of the second battery pack 52 remains unchanged.

[0098] It is understandable that in the first control mode, the BMS directly starts the voltage converter 53 after starting operation, and the battery pack supplies power to the load 55 through the first battery group 51 and the second battery group 52 at the same time.

[0099] When the battery pack is controlled to supply power to the load using the first control method, the control unit directly controls the operation of the voltage converter after startup, and does not need to determine the remaining power in the first battery pack and the second battery pack. The control method is relatively simple.

[0100] In the second control mode of the battery pack, the BMS can control the voltage converter 53 to start operation at an appropriate time based on the remaining charge of the first battery pack 51. For example, when the BMS determines that the remaining charge of the second battery pack 52 has dropped to a first preset threshold, it controls the voltage converter 53 to convert the voltage output by the first battery pack 51 and output a first charging voltage to the second battery pack 52. When the remaining charge of the second battery pack 52 drops to the first preset threshold, the voltage output by the second battery pack 52 is no less than the supply voltage of the load 55.

[0101] In practical applications, the first preset threshold can be set based on the battery type in the second battery pack 52. As shown in Figure 1, if the cells in the second battery pack 52 are sodium-ion single cells, when the remaining charge of the second battery pack 52 drops to 30%, the voltage of the second battery pack 52 will be lower than the supply voltage of the load 55. To prevent the voltage input to the load 55 from falling below the supply voltage VL1 of the load 55, the second preset threshold can be a value higher than the discharge cutoff charge (30%) of the sodium-ion single cell, such as 50% or 60%. Furthermore, when the remaining charge of the second battery pack 52 is not lower than the first preset threshold, the second battery pack 52 can independently power the load for a certain period of time. The first preset threshold can be set based on the power demand of the load 55 in a short period of time.

[0102] Similarly, if the cells in the second battery pack 52 are lithium-ion cells, when the remaining charge of the second battery pack 52 drops to 5%, the voltage of the second battery pack 52 will be lower than the supply voltage of the load 55. To prevent the voltage input to the load 55 from falling below the supply voltage VL1 of the load 55, the first preset threshold value may be a value higher than 5%, such as 20% or 40%.

[0103] In the second control mode, the BMS does not directly start the voltage converter 53 after starting operation. The battery pack first supplies power to the load 55 separately through the second battery pack 52. In the process of supplying power to the load 55 through the second battery pack 52, the BMS obtains the current value in the charge and discharge circuit of the second battery pack 52 through the current sensor 523, and calculates the SOC value of the second battery pack 52 based on the current value. When the SOC value of the second battery pack 52 drops to a first preset threshold value (for example, 60%), the BMS starts the voltage converter 53 to convert the output voltage of the first battery pack 51, obtains and outputs a first charging voltage to the second battery pack 52. After the voltage converter 53 is started, the first battery pack 51 and the second battery pack 52 simultaneously supply power to the load 55.

[0104] When the battery pack is controlled to supply power to the load through the second control method, the second battery pack supplies power to the load alone when the remaining power of the second battery pack is greater than the first preset threshold. At this time, the first battery pack and the voltage converter are in a stopped state, which can avoid power consumption generated by the operation of the voltage converter, thereby reducing the power loss of the first battery pack.

[0105] In the third control mode for the battery pack, the BMS can control the voltage converter 53 to start operation at an appropriate time based on the remaining charge of the first battery pack 51 and the remaining charge of the second battery pack 52. For example, when the BMS determines that the remaining charge of the second battery pack 52 has dropped to a first preset threshold and the remaining charge of the first battery pack 51 is not less than a second preset threshold, it controls the voltage converter 53 to convert the voltage output by the first battery pack 51 and output a first charging voltage to the second battery pack 52. The second preset threshold is not less than the lower limit of the charge of the first battery pack. The first preset threshold is the same as the first preset threshold in the second control mode.

[0106] In practical applications, the second preset threshold value can be set based on the battery type of the first battery pack 51. As shown in Figure 1, if the cells in the first battery pack 51 are sodium-ion cells, the lower limit of the power level can be 5%, or a value close to 5%. When the remaining power level of the first battery pack 51 during each discharge process is equal to or close to 5%, the remaining power level in the first battery pack 51 is low, and the power utilization rate is high.

[0107] In the third control mode, the BMS does not directly start the voltage converter 53 after startup. The battery pack first supplies power to the load 55 through the second battery pack 52. During this process, the BMS obtains the current value in the charge and discharge circuit of the second battery pack 52 through the current sensor 523 and calculates the SOC value of the second battery pack 52 based on the current value. Simultaneously, the BMS obtains the current value in the charge and discharge circuit of the first battery pack 51 through the current sensor 513 and calculates the SOC value of the first battery pack 51 based on the current value.

[0108] When the remaining power in the second battery pack 52 drops to a first preset threshold and the remaining power in the first battery pack 51 is not lower than a second preset threshold, the BMS starts the voltage converter 53 to convert the output voltage of the first battery pack 51 to obtain and output a first charging voltage to the second battery pack 52.

[0109] When the battery pack is controlled to supply power to the load through the third control method, the voltage converter is started when the remaining power of the first battery pack is not less than the second preset threshold and the remaining power of the second battery pack drops to the first preset threshold. This can avoid starting the voltage converter when the first battery pack can no longer discharge, thereby reducing the power consumption of the entire battery pack during operation.

[0110] In some embodiments, after starting the voltage converter 53, the BMS may monitor the remaining power in the first battery pack 51. When the remaining power in the first battery pack 51 drops to a lower power limit, the voltage converter 53 may be stopped. At this time, the second battery pack 52 alone supplies power to the load 55. When the remaining power in the second battery pack 52 approaches the discharge cutoff power of the second battery pack 52, the BMS may send a notification message to the VCU. Upon receiving the notification message, the VCU prompts the user that the battery pack is low and needs to be charged.

[0111] The above are merely illustrative examples. The specific control method of the battery pack can be set according to needs, and this embodiment does not limit this.

[0112] It should be noted that the above is only a brief introduction to the composition and principles of battery packs using the application of battery packs in electric vehicles as an example, and does not limit the scope of application of battery packs. Battery packs can also be used in other electrical devices, and this embodiment does not impose any restrictions on this.

[0113] In summary, during the process of supplying power to the load, the second battery pack directly supplies power to the load, and the second battery pack ensures the load's supply voltage. Simultaneously, the first battery pack charges the second battery pack via a voltage converter to indirectly supply power to the load, thereby decoupling the first battery pack from the load. Because the load's supply voltage is guaranteed by the second battery pack, the discharge of the first battery pack is not constrained by the load's supply voltage. The remaining charge of the first battery pack during power supply can be reduced to a minimum value, achieving full discharge. This allows the first battery pack to have a higher power utilization rate, thereby improving the power utilization rate of the entire battery pack.

[0114] As shown in Figure 1, when the cells in the first battery pack are sodium-ion cells or other similar cells, after the remaining charge of the first battery pack drops below 30%, the voltage converter can still convert the output voltage of the first battery pack and output the first charging voltage to the second battery pack, thereby indirectly supplying power to the load. During the entire discharge process, the remaining charge of the first battery pack can drop to 5% or even lower, thereby achieving a high power utilization rate for the first battery pack.

[0115] Figure 6 is a schematic diagram of voltage variations in a first battery pack according to an embodiment of the present application. When the first battery pack is fully charged, it begins discharging after the voltage converter is activated. Because the discharge of the first battery pack does not necessarily require consideration of the load's supply voltage, the remaining charge in the first battery pack can drop to a lower limit of 5%. The BMS controls the voltage converter to stop operating when the charge drops to 5%. Throughout the discharge process, the charge in the first battery pack varies from 100% to 5%.

[0116] Meanwhile, throughout the discharge process of the first battery pack, the output voltage of the first battery pack gradually decreases from a maximum value VH2 to a minimum value VL2, with the voltage variation range of the first battery pack being VH2 to VL2. Even if the output voltage of the first battery pack drops below VH2, the voltage converter can still convert the output voltage of the first battery pack so that the first charging voltage is within a reasonable voltage range.

[0117] After starting the voltage converter, the BMS can also keep the voltage converter in operation. Because the first battery pack is equipped with a corresponding protection circuit, when the output voltage of the first battery pack falls below the discharge cutoff voltage of the first battery pack, the discharge circuit of the first battery pack is automatically disconnected, and the first battery pack stops discharging. Therefore, when the voltage converter is always in operation, it will not cause excessive discharge of the first battery pack 51 and will not damage the first battery pack.

[0118] As described above, the battery pack provided in the embodiment of the present application has a high power utilization rate. Since the power utilization rate of the battery pack is improved, the battery pack can power the load for a longer time after each charging of the battery pack, which can reduce the charging frequency of the battery pack.

[0119] Moreover, compared to the method shown in FIG2 , the embodiment of the present application does not require redesigning the load. Compared to the method shown in FIG3 , in the embodiment of the present application, since the load supply voltage is guaranteed by the second battery pack, a lower power voltage converter can be selected. The voltage converter has lower cost, higher reliability, and lower power consumption during use.

[0120] In some embodiments, during the process of charging the second battery pack via the first battery pack, the remaining power of the second battery pack can be controlled to not exceed a third preset threshold. The third preset threshold can be a level lower than the power of the second battery pack. Furthermore, when the remaining power of the second battery pack approaches or equals the third preset threshold, the second battery pack can independently power the load for a certain period of time. The third preset threshold can be set as required.

[0121] FIG7 is a schematic diagram of voltage changes in a second battery pack according to an embodiment of the present application. Taking FIG5 as an example, the third preset threshold value may be 80% of the charge level of the second battery pack. When the BMS controls the voltage converter 53 to output the first charging voltage to the second battery pack 52, upon detecting that the SOC of the second battery pack 52 reaches 80%, the BMS controls the voltage converter 53 to stop operating or disconnects the charging circuit of the second battery pack 52, thereby stopping charging the second battery pack 52. It is understood that when the charging circuit of the second battery pack 52 is disconnected, the discharge circuit of the second battery pack 52 is not disconnected, and the second battery pack 52 can still supply power to the load.

[0122] In the process of controlling the first battery group 51 to output the first charging voltage to the second battery group 52, the voltage converter 53 is stopped when the remaining power in the second battery group 52 reaches the third preset threshold value, so that the first battery group 51 can stop charging the second battery group 52, thereby avoiding the first battery group 51 from charging a large amount of power to the second battery group 52, thereby reducing the power loss caused by the first battery group 51 charging the second battery group 52.

[0123] As shown in Figure 7, when the cells in the second battery pack 52 are sodium-ion single cells, the discharge cutoff capacity of the second battery pack 52 is 30%. During operation of the electric vehicle, when the remaining capacity in the first battery pack 51 drops to 5%, the voltage converter 53 stops operating, and the second battery pack 52 alone supplies power to the load 55. After the second battery pack 52 alone supplies power to the load 55, if the remaining capacity of the second battery pack 52 drops to 30%, the voltage provided by the battery pack to the load 55 falls below the load's operating voltage, the load stops operating, and the second battery pack 52 stops discharging.

[0124] It is understood that when the remaining power of the second battery pack 52 is not greater than 80% while supplying power to the load 55, the BMS stops the voltage converter 53 upon detecting that the remaining power of the second battery pack 52 reaches 80%. At the same time, when the remaining power of the second battery pack 52 is not less than 30%, the BMS controls the second battery pack 52 to stop discharging when the remaining power of the second battery pack 52 drops to 30%.

[0125] Therefore, when the battery cells in the second battery pack 52 are sodium-ion single cells, when the second battery pack 52 supplies power to the load, the output voltage of the second battery pack 52 is not higher than VH3 and not lower than VL1, which can ensure that the voltage input to the load 55 is not lower than the power supply voltage of the load 55.

[0126] It should be noted that when the battery pack is charged by the onboard charger, the charge in the second battery pack 52 can reach or approach 100%, and the output voltage of the second battery pack 52 can reach or approach VH2. That is, after the second battery pack 52 is fully charged and has been supplying power to the load 55 for a period of time, the remaining charge in the second battery pack 52 drops below a third preset threshold. When the remaining charge in the second battery pack 52 drops below the third preset threshold, the BMS controls the voltage converter 53 to output the first charging voltage to the second battery pack 52, ensuring that the remaining charge in the second battery pack 52 does not exceed the third preset threshold.

[0127] In some embodiments, the capacity of the first battery pack is greater than the capacity of the second battery pack. The capacity of the first battery pack is the total amount of electricity that can be stored in the first battery pack, and the capacity of the second battery pack is the total amount of electricity that can be stored in the second battery pack. Exemplarily, the capacity of the first battery pack can be M times the capacity of the second battery pack, where M is greater than 1. For example, if the first battery pack is composed of N battery modules connected in parallel, and the second battery pack is composed of L battery modules connected in parallel, and the capacity of each battery module is C, then the capacity of the first battery pack is N×C, and the capacity of the second battery pack is L×C, where M=N / L.

[0128] When M is greater than 1, the power of the first battery pack can be greater than the power of the second battery pack. M can be 1.5, 2.7, 4, 6.5, 7, 8.4, 9, 10, etc., which is not limited in this embodiment.

[0129] It is understandable that the power of the first battery pack can meet the power demand of the load in the electrical device in a short period of time, and the total power of the first battery pack and the second battery pack can be set by the power demand of the electrical device in a longer period of time.

[0130] Among them, the total power of the battery pack is equal to the sum of the power of the first battery group and the second battery group. Since the power utilization rate of the first battery group is higher, the higher the proportion of the power of the first battery group in the total power of the battery pack, the higher the power utilization rate of the entire battery pack.

[0131] In the embodiment of the present application, setting the power of the first battery group to be greater than the power of the second battery group can increase the proportion of the power of the first battery group in the total power of the battery pack, thereby making the battery pack have a higher power utilization rate.

[0132] In some embodiments, the power of the first battery pack and the power of the second battery pack may be the same. For example, the first battery pack and the second battery pack may include the same number of battery modules, and the power of each battery module is the same.

[0133] In some embodiments, the voltage converter is a bidirectional voltage converter; the control unit is further configured to control the voltage converter to convert the recovered voltage and output a second charging voltage to the first battery pack when the load outputs the recovered voltage to the second battery pack.

[0134] As shown in FIG5 , when the voltage converter 53 is a bidirectional voltage converter, the first terminal 531 of the voltage converter 53 has not only a voltage input function but also a voltage output function. Similarly, the second terminal 532 has not only a voltage output function but also a voltage input function.

[0135] When the voltage converter 53 is a bidirectional voltage converter, the BMS can control the voltage converter 53 to convert the output voltage of the first battery group 51 to obtain and input the first charging voltage to the second battery group 52. Alternatively, the BMS can control the voltage converter 53 to convert the output voltage of the second battery group 52 to obtain and input the second charging voltage to the first battery group 51.

[0136] Taking an electric vehicle as an example, the electric drive system includes a drive motor and a motor controller. During the braking process of the electric vehicle, the wheels can drive the drive motor to rotate, and the drive motor becomes an AC generator to output current. The motor controller rectifies the current output by the drive motor into direct current and inputs a voltage to the positive and negative terminals of the second battery pack 52. This voltage is the recovery voltage.

[0137] In some embodiments, when the BMS detects that the motor controller inputs a recovery voltage to the second battery pack 52, it first detects the amount of power in the first battery pack 51. When the power in the first battery pack 51 is not full and can continue to be charged, the BMS controls the voltage converter 53 to convert the recovery voltage, obtains and inputs a charging voltage (the charging voltage is the second charging voltage) to the first battery pack 51 to charge the first battery pack 51.

[0138] For example, the BMS can detect the current flow direction in the charge and discharge circuit of the second battery pack 52 through the current sensor 523. When the current flow direction is opposite to the current flow direction during the discharge process, the motor controller determines that the motor controller starts to input the regenerative voltage to the second battery pack 52. At this time, the BMS can control the voltage converter 53 to convert the regenerative voltage to obtain and input the second charging voltage to the first battery pack 51.

[0139] In some embodiments, when the BMS detects that the motor controller is inputting a regenerative voltage to the second battery pack 52, it first detects the remaining power in the second battery pack 52. When the remaining power in the second battery pack 52 reaches or approaches 100%, it controls the voltage converter 53 to convert the regenerative voltage to charge the first battery pack 51. If the second battery pack 52 is not fully charged and can continue to be charged, the voltage converter 53 is not controlled to convert the regenerative voltage, and the regenerative voltage is used to charge the second battery pack 52.

[0140] As shown in Figure 7, after the second battery pack 52 has supplied power to the load 55 for a period of time, the remaining charge in the second battery pack 52 is no more than 80%. Therefore, when the BMS detects that the motor controller is inputting a regenerative voltage to the second battery pack 52, it may initially disable control of the voltage converter 53 to convert the regenerative voltage, allowing the regenerative voltage to charge the second battery pack 52 first. When the remaining charge in the second battery pack 52 approaches or equals 100%, the voltage converter 53 is activated to convert the regenerative voltage, inputting the first charging voltage to the first battery pack 51, and charging the first battery pack 51.

[0141] It can be understood that after the remaining power in the second battery pack 52 drops to the third preset threshold value, the remaining power in the second battery pack 52 is controlled not to be higher than the third preset threshold value. When the load inputs the recovery voltage to the second battery pack 52, the recovery voltage can be used to charge the second battery pack first, which can avoid the recovery voltage directly charging the first battery pack, thereby reducing the power loss caused by the operation of the voltage converter.

[0142] It is understandable that electrical devices include but are not limited to electric vehicles. In other electrical devices, when the voltage converter is a bidirectional voltage converter and the load can input a recovery voltage to the second battery pack, the control unit can control the voltage converter to convert the recovery voltage and input the second charging voltage to the first battery pack to charge the first battery pack.

[0143] In an embodiment of the present application, when the voltage converter is a bidirectional voltage converter, the control unit can control the voltage converter to convert the recovery voltage of the load input to the second battery group, and input the charging voltage to the first battery group, so that the electricity fed back by the load can be recovered through the first battery group.

[0144] It should be noted that when the voltage converter is unidirectional, if the load inputs a recovered voltage to the second battery pack and the remaining charge in the second battery pack is high, the charge input by the load to the second battery pack will be discarded. However, when the voltage converter is bidirectional, this charge can be input to the first battery pack through the voltage converter, thereby improving the recovery rate of the charge fed back by the load.

[0145] In some embodiments, when the ambient temperature in the environment in which the battery pack is located is low and the load is in a stopped state, the BMS can control the voltage converter to convert the voltage output by one of the first battery pack and the second battery pack, obtain and output the charging voltage to the other battery pack, so that the entire battery pack is in an operating state, thereby increasing the temperature of the battery pack.

[0146] As shown in Figure 5, the VCU can send a heating signal to the BMS when the vehicle is stopped and the ambient temperature is below a preset temperature. After receiving the heating signal, the BMS first obtains the remaining charge in the first battery pack 51 and the remaining charge in the second battery pack 52. It then determines the target battery pack from the first and second battery packs 51, 52 whose remaining charge is below a fourth preset threshold. The BMS then activates the voltage converter to convert the output voltage of the other battery pack, obtains the charging voltage, and outputs it to the target battery pack to charge it.

[0147] The fourth preset threshold is the power value at which the battery pack can continue to be charged, and the fourth preset threshold can be specifically set according to needs.

[0148] When the remaining power of the first battery pack 51 and the second battery pack 52 are both lower than a fourth preset threshold, any one of the battery packs can be selected as the target battery pack.

[0149] It should be noted that when the voltage converter is a unidirectional voltage converter, if the ambient temperature in the battery pack's environment is low and the load is in an idle state, the control unit may control the voltage converter to convert the output voltage of the first battery pack and output a charging voltage to the second battery pack when the remaining charge of the second battery pack is below a fourth preset threshold. When the voltage converter is a bidirectional voltage converter, the voltage converter may select the battery pack with the remaining charge below the fourth preset threshold from the first and second battery packs as the target battery pack.

[0150] Charging the second battery group 52 through the first battery group 51 and / or charging the first battery group 51 through the second battery group 52 can put the first battery group 51 and the second battery group 52 in a charging or discharging state, thereby increasing the temperature of the first battery group 51 and the second battery group 52 and heating the battery pack.

[0151] During the heating of the battery pack, the BMS may control the voltage converter 53 to input a first charging voltage for a preset duration to the second battery pack 52, thereby charging the second battery pack 52 for a preset duration. Alternatively, the BMS may control the voltage converter 53 to input a second charging voltage for a preset duration to the first battery pack 51, thereby charging the first battery pack 51 for a preset duration.

[0152] Alternatively, the BMS may control the voltage converter to charge the first battery group 51 and the second battery group 52 alternately, with each battery group being charged for a certain period of time.

[0153] In an embodiment of the present application, the battery pack includes a first battery group and a second battery group. The control unit can charge the first battery group and the second battery group with each other when the battery pack stops supplying power to the load and the ambient temperature is lower than a preset temperature, so that the two battery groups are in an operating state, thereby heating the battery pack.

[0154] In some embodiments, the battery pack includes a plurality of first battery groups, and each first battery group is respectively connected to the first end of the voltage converter. Figure 8 is a schematic diagram of the power supply principle of another electrical device provided in an embodiment of the present application. The battery pack includes a first battery group 1 and a first battery group 2, as well as a control unit, a voltage converter and a second battery group, and the second battery group is used to connect to the load to supply power to the load. The voltage converter has multiple first ends (the first end has a voltage input function or has a voltage input and output function), such as the input end I1 and the input end I2 shown in Figure 8. The first battery group 1 is connected to the input end I1, and the first battery group 2 is connected to the input end I2.

[0155] In the process of controlling the voltage converter to input the first charging voltage to the second battery group, the control unit can select a first battery group with a remaining power greater than the lower limit value from the first battery group 1 and the second battery group 2, convert the output voltage of the selected first battery group, obtain and input the first charging voltage to the second battery group.

[0156] In some embodiments, the voltage converter can be composed of multiple voltage conversion modules, such as the DC boost circuit or DC buck circuit in the above examples, or a boost-buck circuit with both boost and buck functions. The types of voltage conversion modules include but are not limited to the above examples.

[0157] Each voltage conversion module has a first end and a second end, the first end being connected to one of the first battery packs, and the second end being connected to the second battery pack. When controlling the voltage converter to output the first charging voltage to the second battery pack, the control unit may determine, from the plurality of first battery packs, a first battery pack having a remaining charge greater than a lower charge limit, and activate the corresponding voltage conversion module to convert the output voltage of the determined first battery pack to obtain and output the first charging voltage to the second battery pack.

[0158] Among them, when the battery pack includes multiple first battery groups, in the process of controlling the voltage converter to input the second charging voltage to the first battery group, the control unit can select a first battery group whose remaining power is lower than a fourth preset threshold from the multiple first battery groups, and input the second charging voltage to the first battery group.

[0159] In some embodiments, the battery pack includes a plurality of second battery groups, each of which is connected to a second terminal of the voltage converter. Exemplarily, the voltage converter has a plurality of second terminals, and each of the second battery groups is connected to one of the second terminals.

[0160] FIG9 is a schematic diagram of the power supply principle of another electrical device provided in an embodiment of the present application. The battery pack includes a first battery pack, a control unit and a voltage converter, as well as a second battery pack 1 and a second battery pack 2. The second battery pack 1 and the second battery pack 2 are used to connect to a load to supply power to the load. The voltage converter has multiple second terminals (the second terminals have a voltage output function or a voltage input and output function), such as the output terminal O1 and the output terminal O2 shown in FIG9. The second battery pack 1 is connected to the output terminal O1, and the second battery pack 2 is connected to the output terminal O2.

[0161] In the process of controlling the second battery pack 1 and the second battery pack 2 to supply power to the load, the control unit may select a second battery pack from the second battery pack 1 and the second battery pack 2 whose remaining power is greater than a first preset threshold value to supply power to the load. At the same time, when the remaining power of either of the second battery pack 1 and the second battery pack 2 drops to the first preset threshold value, the control unit may control the voltage converter to start operating to input a first charging voltage to the battery pack.

[0162] It can be understood that when the battery pack includes multiple second battery groups, the control unit can control one of the second battery groups to power the load, and at the same time control the voltage converter to convert the output voltage of the first battery group, obtain and output the first charging voltage to other second battery groups to charge the other second battery groups.

[0163] In some embodiments, the battery pack includes a plurality of first battery groups and a plurality of second battery groups, each first battery group is respectively connected to a first end of the voltage converter, and each second battery group is respectively connected to a second end of the voltage converter.

[0164] As shown in Figure 10, Figure 10 is a schematic diagram of the power supply principle of another electrical device provided in an embodiment of the present application. The battery pack includes a first battery group 1, a first battery group 2, a control unit and a voltage converter, as well as a second battery group 1 and a second battery group 2. The second battery group 1 and the second battery group 2 are used to connect to a load to supply power to the load. The voltage converter has an input terminal I1 and an input terminal I2. The first battery group 1 is connected to the input terminal I1, and the first battery group 2 is connected to the input terminal I2. At the same time, the voltage converter has an output terminal O1 and an output terminal O2. The second battery group 1 is connected to the output terminal O1, and the second battery group 2 is connected to the output terminal O2.

[0165] Among them, when the battery pack includes multiple first battery groups, in the process of outputting the first charging voltage to the second battery group, the control unit can determine a first battery group whose remaining power is greater than the lower limit value of power from the multiple first battery groups, and control the voltage converter to convert the output voltage of the determined first battery group to obtain and output the first charging voltage to the second battery group.

[0166] Among them, when the battery pack includes multiple second battery groups, in the process of outputting the first charging voltage to the second battery group, the control unit can determine the second battery group whose remaining power drops to a first preset threshold from the multiple second battery groups, and control the voltage conversion unit to output the first charging voltage to the second battery group whose remaining power drops to the first preset threshold.

[0167] In an embodiment of the present application, when the battery pack includes multiple first battery packs, the multiple first battery packs can take turns providing voltage to the voltage converter to provide the first charging voltage to the second battery pack. When the battery pack includes multiple second battery packs, any one of the multiple second battery packs can power the load.

[0168] In some embodiments, the first battery pack can be assembled from multiple sodium-ion single cells connected in series and / or in parallel. When supplying power to a load, the first battery pack is not restricted by the load's supply voltage during discharge, so the first battery pack can fully discharge. When the first battery pack is assembled from multiple sodium-ion single cells, the power utilization rate of the first battery pack is not affected. At the same time, because sodium-ion batteries are lower in cost and have a higher discharge rate than lithium-ion batteries, the cost of the entire battery pack can be reduced.

[0169] It should be noted that the first battery pack can also be assembled from multiple lithium-ion single cells in series and / or parallel. Since the discharge process of the first battery pack is not restricted by the supply voltage of the load, when the first battery pack is composed of multiple lithium-ion single cells, the discharge capacity of the first battery pack can drop below the discharge cutoff capacity (5%), and full discharge can be achieved. Compared with other battery packs composed of lithium-ion single cells, the embodiment of the present application can also improve the power utilization rate of the battery pack.

[0170] In some embodiments, the second battery pack may be assembled from a plurality of sodium-ion cells or a plurality of lithium-ion cells. As can be seen from the above examples, when the second battery pack is composed of a plurality of sodium-ion cells, the cost of the second battery pack can be reduced, thereby reducing the cost of the entire second battery pack.

[0171] When the second battery pack is assembled from multiple lithium-ion single cells, the lithium-ion cells have a lower discharge cut-off capacity, so the second battery pack can be fully discharged during the discharge process, thereby improving the power utilization rate of the second battery pack and thus improving the power utilization rate of the entire battery pack.

[0172] The present application also provides a control method, which is applied to the control unit of the battery pack in the above example. As shown in Figure 11, Figure 11 is a flowchart of the steps of a control method provided by the present application. The method may include the following steps:

[0173] Step 111: The control unit controls the voltage converter to convert the voltage output by the first battery pack and output a first charging voltage to the second battery pack.

[0174] In some embodiments, before step 111, the method may further include: a control unit determines that the remaining power in the second battery pack drops to a first preset threshold; wherein, when the remaining power in the second battery pack drops to the first preset threshold, the voltage output by the second battery pack is not lower than the power supply voltage of the load.

[0175] In some embodiments, before step 111, the method may further include: a control unit determines that the remaining power in the second battery pack drops to a first preset threshold value, and the remaining power in the first battery pack is not lower than a second preset threshold value; wherein, when the remaining power in the second battery pack drops to the first preset threshold value, the voltage output by the second battery pack is not lower than the power supply voltage of the load, and the second preset threshold value is not lower than the lower limit value of the power of the first battery pack.

[0176] In some embodiments, the method may further include: when the load outputs the recovery voltage to the second battery pack, the control unit controls the voltage converter to convert the recovery voltage and output a second charging voltage to the first battery pack.

[0177] In some embodiments, the method may further include: when the ambient temperature is lower than a preset temperature and the load stops running, the control unit controls the voltage converter to convert the voltage output by one of the first battery pack and the second battery pack to obtain and output a charging voltage to the other battery pack.

[0178] Among them, the understanding of the control method can be connected to the introduction of the principle of the battery pack in the above example, and this embodiment will not be repeated here.

[0179] An embodiment of the present application further provides an electrical device, which includes the battery pack described above.

[0180] An embodiment of the present application also provides a readable storage medium, which is used to store a computer program. When the computer program code is executed by a control unit in the battery pack, the battery management system executes the control method described above.

[0181] An embodiment of the present application also provides a vehicle, comprising the battery pack described above.

[0182] The above are merely optional embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A battery pack, wherein: The battery pack includes a control unit, a first battery pack, a voltage converter and a second battery pack; The first battery pack is connected to the first end of the voltage converter; The second battery pack is connected to the second end of the voltage converter, and the second battery pack is connected to a load; The control unit is connected to the first battery pack, the voltage converter and the second battery pack respectively, and is used to control the voltage converter to convert the voltage output by the first battery pack and output a first charging voltage to the second battery pack.

2. The battery pack according to claim 1, wherein: The power of the first battery pack is greater than or equal to the power of the second battery pack.

3. The battery pack according to claim 2, wherein: The power of the first battery pack is M times that of the second battery pack, where M is greater than or equal to 1 and less than or equal to 10.

4. The battery pack according to any one of claims 1 to 3, wherein: The voltage converter is a bidirectional voltage converter; The control unit is further configured to control the voltage converter to convert the recovered voltage and output a second charging voltage to the first battery pack when the load outputs the recovered voltage to the second battery pack.

5. The battery pack according to any one of claims 1 to 4, wherein: The battery pack includes a plurality of first battery groups, and each of the first battery groups is connected to the first end of the voltage converter.

6. The battery pack according to any one of claims 1 to 5, wherein: The battery pack includes a plurality of second battery groups, and each of the second battery groups is connected to the second end of the voltage converter.

7. The battery pack according to any one of claims 1 to 6, wherein: The first battery pack is assembled from a plurality of sodium ion single batteries.

8. The battery pack according to any one of claims 1 to 7, wherein: The second battery pack is assembled from a plurality of sodium ion single batteries or a plurality of lithium ion single batteries.

9. A control method, wherein: A control unit applied to a battery pack, the battery pack further comprising a first battery pack, a second battery pack, and a voltage converter, the first battery pack being connected to a first end of the voltage converter, the second battery pack being connected to a second end of the voltage converter, the second battery pack being connected to a load, the control unit being connected to the first battery pack, the voltage converter, and the second battery pack, respectively, the method comprising: The control unit controls the voltage converter to convert the voltage output from the first battery pack and output a first charging voltage to the second battery pack.

10. The control method according to claim 9, wherein: Before controlling the voltage converter to convert the voltage output by the first battery pack, the method further includes: The control unit determines that the remaining power of the second battery pack drops to a first preset threshold; When the remaining power of the second battery pack drops to the first preset threshold, the voltage output by the second battery pack is not lower than the power supply voltage of the load.

11. The control method according to claim 9 or 10, wherein: Before controlling the voltage converter to convert the voltage output by the first battery pack, the method further includes: The control unit determines that the remaining power of the first battery pack is not lower than a second preset threshold value, and the second preset threshold value is not lower than a lower limit value of the power of the first battery pack.

12. The control method according to any one of claims 9 to 11, wherein: The method further comprises: When the load outputs a recovery voltage to the second battery pack, the control unit controls the voltage converter to convert the recovery voltage and output a second charging voltage to the first battery pack.

13. The method according to any one of claims 9 to 12, wherein: The method further comprises: When the ambient temperature is lower than a preset temperature and the load stops running, the control unit controls the voltage converter to convert the voltage output by one of the first battery pack and the second battery pack to obtain and output a charging voltage to the other battery pack.

14. An electrical device, wherein: The electrical device comprises the battery pack according to any one of claims 1 to 8.

15. A readable storage medium, wherein: The readable storage medium is used to store computer program code, and when the computer program code is executed by a control unit in the battery pack, the control unit executes the method according to any one of claims 9 to 13.

16. A vehicle, wherein The vehicle includes the battery pack according to any one of claims 1 to 8.

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