Multifunctional low-voltage energy storage device and low-voltage energy storage system

Abstract

The invention discloses a multifunctional low-voltage energy storage device and a low-voltage energy storage system, and the device comprises a housing, a current transmission conversion unit, an energy storage control unit, an output switch unit, and an output selection switch. Wherein an alternating current inlet wire interface is embedded in the shell and used for being connected with external alternating current, outputting the alternating current to the output switch unit after the alternating current passes through the current transmission unit and / or converting the alternating current into direct current through the current transmission unit to charge the energy storage control unit, and the energy storage control unit is further connected with the output switch unit. The output selection switch is used for outputting direct current to the output switch unit, the output selection switch is used for receiving control of the energy storage control unit and controlling a working output interface in the output switch unit to be an alternating current power supply interface or a direct current power supply interface, and then direct current or alternating current is selected to be output according to the power utilization type of a load. An energy storage device is single in power supply mode, high in cost and poor in applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage equipment, and in particular to a multifunctional low-voltage energy storage device and a low-voltage energy storage system. Background Art

[0002] In the current work and life scenarios, the diversity of electrical equipment has resulted in a single DC power supply device or a single AC power supply device being unable to provide two power supply modes at the same time. This has led to users needing to have energy storage devices with two different power supply modes as backup, which has increased the user's usage costs and required a larger space for installation and use.

[0003] Therefore, how to solve the technical problems in the related technology that the energy storage device can only be powered by a single AC power supply mode or a single DC power supply mode, the high equipment cost and poor applicability when the user needs to equip two power supply modes, has become a technical difficulty that technical personnel in this field need to overcome. Summary of the invention

[0004] The present invention provides a multifunctional low-voltage energy storage device and a low-voltage energy storage system to solve the technical problems of the energy storage device in the related art, such as single power supply mode, high cost and poor applicability.

[0005] A multifunctional low-voltage energy storage device in the present invention comprises:

[0006] A shell having a cavity, wherein an AC line interface is embedded in the shell, and the AC line interface is used to connect external AC power;

[0007] A current transmission conversion unit, fixedly disposed in the cavity, connected to the AC line interface, and used to receive the external AC power;

[0008] An energy storage control unit, fixedly disposed in the cavity, connected to the current transmission and conversion unit, and configured to receive and store electrical energy, or output direct current to the current transmission and conversion unit;

[0009] An output switch unit is fixedly disposed in the cavity, wherein the input end of the output switch unit is respectively connected to the output end of the current transmission conversion unit and the charge and discharge interface of the energy storage control unit, and the output end of the output switch unit is respectively connected to the AC power supply interface and the DC power supply interface;

[0010] The output selection switch is fixedly arranged on the surface of the shell, one end of the output selection switch is connected to the control end of the energy storage control unit, and the other end of the output selection switch is connected to the control end of the output switch unit.

[0011] A multifunctional low-voltage energy storage device according to an embodiment of the present invention has at least the following beneficial effects:

[0012] The embodiment of the present invention provides a multifunctional low-voltage energy storage device, which is provided with a shell, a current transmission conversion unit, an energy storage control unit, an output switch unit and an output selection switch; wherein an AC input line interface is embedded in the shell, which is used to connect external AC power, output AC power to the output switch unit after passing through the current transmission unit and / or convert AC power into DC power through the current transmission unit to charge the energy storage control unit, the energy storage control unit is also connected to the output switch unit, and is used to output DC power to the output switch unit, the output selection switch is used to receive control of the energy storage control unit, and is used to control the working output interface in the output switch unit to be an AC power supply interface or a DC power supply interface, thereby realizing the selection of outputting DC power or AC power according to the power consumption type of the load, solving the technical problems in the related art that the energy storage device can only be powered by a single AC power supply mode or a single DC power supply mode, the equipment cost is high and the applicability is poor when the user needs to equip two power supply modes, and provides a multifunctional low-voltage energy storage device that integrates DC power supply and AC power supply, is low-cost and has strong applicability.

[0013] According to some other embodiments of the multifunctional low-voltage energy storage device of the present invention, the energy storage control unit includes an energy storage battery pack and a BMS controller;

[0014] The BMS controller is connected to the energy storage battery pack and is used to control the charge and discharge state of the energy storage battery pack;

[0015] The BMS controller is also connected to the output selection switch to control the working state of the output selection switch, and further control the working state of the output switch unit to achieve AC output or DC output.

[0016] According to some other embodiments of the multifunctional low-voltage energy storage device of the present invention, the output switch unit includes a first relay switch and a second relay switch;

[0017] The input end of the first relay is connected to the output end of the current transmission conversion unit, the output end of the first relay is connected to the AC power supply interface, and the control end of the first relay switch is connected to the output selection switch;

[0018] The input end of the second relay switch is connected to the charging and discharging interface of the energy storage control unit, the output end of the second relay switch is connected to the DC power supply interface, and the start finger end of the second relay switch is connected to the output selection switch.

[0019] According to some other embodiments of the multifunctional low-voltage energy storage device of the present invention, the current transmission conversion unit includes an inverter;

[0020] The AC input interface of the inverter is connected to the AC line interface, the AC output interface of the inverter is connected to the input end of the output switch unit, and the DC input and output interface of the inverter is connected to the charge and discharge interface of the energy storage control unit.

[0021] According to some other embodiments of the present invention, the multifunctional low-voltage energy storage device further comprises a DC fast charging interface;

[0022] The DC fast charging interface is embedded in the shell, and the DC fast charging interface is connected to the charging and discharging interface of the energy storage control unit, and is used to connect to an external DC voltage source to charge the energy storage control unit.

[0023] According to some other embodiments of the present invention, the multifunctional low-voltage energy storage device further comprises a parallel connection interface;

[0024] The parallel interface is embedded in the housing, and is connected in parallel with the AC line interface. The parallel interface is used to connect to the AC line interface of another multifunctional low-voltage energy storage device.

[0025] In a second aspect, an embodiment of the present invention further provides a low-voltage energy storage system, comprising a first multifunctional low-voltage energy storage device and a second multifunctional low-voltage energy storage device, wherein the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device are both multifunctional low-voltage energy storage devices as described above; the connection relationship between the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device includes one or more of the following:

[0026] The first multifunctional low-voltage energy storage device is connected to the second multifunctional low-voltage energy storage device via a first connecting line to increase the AC power storage capacity or DC power storage capacity of the low-voltage energy storage system;

[0027] Furthermore, the first multifunctional low-voltage energy storage device is connected to the second multifunctional low-voltage energy storage device via a second connecting line to increase the DC power supply power of the low-voltage energy storage system.

[0028] According to some other embodiments of the low-voltage energy storage system of the present invention, the first connecting line is used to connect the AC power supply interface of the first multifunctional low-voltage energy storage device and the AC incoming line interface of the second multifunctional low-voltage energy storage device.

[0029] According to some other embodiments of the low-voltage energy storage system of the present invention, the second connecting line is used to connect the DC power supply interface of the first multifunctional low-voltage energy storage device and the DC fast charging interface of the second multifunctional low-voltage energy storage device.

[0030] According to some other embodiments of the present invention, the low-voltage energy storage system further includes a third connecting line, which is used to connect the parallel interface of the first multifunctional low-voltage energy storage device and the AC input interface of the second multifunctional low-voltage energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a first embodiment of a multifunctional low-voltage energy storage device of the present invention.

[0032] Figure 2 It is a module composition intention of a specific embodiment of an energy storage control unit in a multifunctional low-voltage energy storage device of the present invention;

[0033] Figure 3 This is a second embodiment of a multifunctional low-voltage energy storage device of the present invention.

[0034] Figure 4 This is a module composition intention of the third embodiment of a multifunctional low-voltage energy storage device of the present invention;

[0035] Figure 5 This is a module composition intention of the fourth embodiment of a multifunctional low-voltage energy storage device of the present invention;

[0036] Figure 6 It is a schematic diagram of the circuit frame structure of a multifunctional low-voltage energy storage device of the present invention;

[0037] Figure 7 It is a schematic diagram of the module composition of a specific embodiment of a low-voltage energy storage system of the present invention;

[0038] Figure 8 It is a schematic diagram of the circuit framework structure of a specific embodiment of increasing the AC power storage capacity or increasing the DC power storage capacity in a low-voltage energy storage system of the present invention;

[0039] Fig. 9 It is a schematic diagram of the circuit frame composition structure of a specific embodiment of increasing DC power supply power in a low-voltage energy storage system of the present invention. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the concept of the invention and the technical effects produced in combination with the embodiments, so as to fully understand the purpose, characteristics and effects of the invention. Obviously, the described embodiments are only part of the embodiments of the invention, not all of them. Based on the embodiments of the invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the invention.

[0041] In the description of the embodiments of the present invention, if "several" is involved, it means more than one, if "multiple" is involved, it means more than two, if "greater than", "less than" or "exceed" is involved, it should be understood as not including the number itself, if "above", "below" or "within" is involved, it should be understood as including the number itself. If "first" or "second" is involved, it should be understood as being used to distinguish technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0042] Reference Figure 1 , an embodiment of the present invention provides a multifunctional low-voltage energy storage device, which includes a shell, a current transmission conversion unit, an energy storage control unit, an output switch unit and an output selection switch; wherein the shell is provided with a cavity, the current transmission conversion unit, the energy storage control unit, and the output switch unit are respectively fixedly arranged in the cavity, and the surface of the shell is embedded with an AC input line interface, a DC power supply interface and an AC power supply interface. In this embodiment, the AC input line interface is connected to the current transmission conversion unit for connecting external AC power to the current transmission conversion unit, the current transmission conversion unit is connected to the charging and discharging interface of the energy storage control unit, the output end (AC output end) of the current transmission conversion unit is connected to the input end of the output switch unit, the output end of the output switch unit is connected to the AC power supply interface, the control end of the energy storage control unit is connected to one end of the output selection switch, and the other end of the output selection switch is connected to the output switch unit. When AC power needs to be output externally, the output selection switch state is switched to AC power output, and then, after connecting to external AC power through the current transmission conversion unit, AC power can be output externally, and DC power is output to the energy storage control unit for charging at the same time; when external AC power is not connected and the external load needs AC power supply, the energy storage control unit outputs DC power to the current transmission conversion unit, and the current transmission conversion unit converts the received DC power into AC power and transmits it to the AC power supply interface through the output switch unit, thereby providing AC power supply to the external load; when the external load needs DC power supply, the output selection switch state is switched to DC power output, and then the charging and discharging interface of the energy storage control unit outputs DC power to the input end of the output switch unit, and then transmits it to the DC power supply interface through the output switch unit, thereby providing DC power supply to the external load. The embodiment of the present invention is a multifunctional low-voltage energy storage device, which selects to output DC power or AC power according to the power consumption type of the load, and solves the technical problems in the related art that the energy storage device can only be powered by a single AC power supply mode or a single DC power supply mode, the power supply mode is single, the equipment cost is high when the user needs to equip two power supply modes, and the applicability is poor.

[0043] Reference Figure 2In some embodiments, in order to ensure the stability of the operation of the energy storage control unit, the energy storage control unit is ensured to be safely and accurately controlled during charging and discharging. In this embodiment, the energy storage control unit includes an energy storage battery pack and a BMS controller; wherein the BMS controller is connected to the energy storage battery pack, and the energy storage battery pack is provided with a charge and discharge interface, and the charge and discharge interface is respectively connected to the current transmission conversion unit and the output switch unit, and the BMS controller is used to control the charge and discharge state of the energy storage battery pack, and can also monitor the power information of the energy storage battery pack, and can prevent the energy storage battery pack from being overcharged or over-discharged. In this embodiment, the BMS controller is also connected to the output selection switch, and when the output selection switch selects the power supply state (DC output or AC output), the BMS controller can control the output switch unit to close to the corresponding DC power supply interface or AC power supply interface.

[0044] In some embodiments, in order to satisfy the functions of AC power transmission and AC-to-DC conversion of the current transmission conversion unit in the above embodiments. In this embodiment, the current transmission conversion unit includes an inverter; wherein the AC input interface is connected to the AC input interface of the inverter, the AC output interface of the inverter is connected to the input end of the output switch unit, and the DC input and output interface of the inverter is connected to the charging and discharging interface of the energy storage control unit, which is used to convert AC power into DC power to charge the energy storage control unit, or to receive the DC power output by the energy storage control unit and convert it into AC power and then transmit it to the AC power supply interface through the output switch unit, thereby realizing AC power supply for the external load.

[0045] Reference Figure 3In some embodiments, in order to stably provide AC or DC power to an external load, in this embodiment, the output switch unit includes a first relay switch and a second relay switch, and then by setting two relay switches for controlling AC output and DC output respectively, the physical isolation output of AC and DC can be achieved. In this embodiment, the input end of the first relay switch is connected to the AC output end of the inverter (current transmission conversion unit), the output end of the first relay switch is connected to the AC power supply interface, and the control end of the first relay switch is connected to the output selection switch. Then, when the output selection switch is switched to the AC output state, the BMS controller can control the first relay switch to close. At this time, the AC output by the inverter is output to the AC power supply interface through the first relay switch, so as to provide AC power to the external load. The input end of the second relay switch is connected to the charging and discharging interface in the energy storage control unit, the output end of the second relay switch is connected to the DC power supply interface, and the control end of the second relay switch is connected to the output selection switch. Furthermore, when the output selection switch is switched to the DC output state, the BMS controller in the energy storage control unit can control the second relay switch to close. At this time, the BMS controller controls the energy storage battery pack to output DC power to the second relay switch, and provides DC power supply to the external load through the DC power supply interface.

[0046] In some embodiments, the output selection switch described in the above embodiments is implemented by a manual switch, which is embedded and fixed on the surface of the shell. When the user uses the multifunctional low-voltage energy storage device proposed in the embodiment of the present invention, the user can slide the manual switch to the corresponding output state according to the power supply type required by the external load.

[0047] Reference Figure 4 In some embodiments, in order to facilitate users to perform fast charging, the use efficiency of the multifunctional low-voltage energy storage device proposed in the embodiment of the present invention is improved, and a good user experience is given to users. In this embodiment, the multifunctional low-voltage energy storage device also includes a DC fast charging interface, which is embedded in the surface of the shell, and the DC fast charging interface is connected to the charging and discharging interface in the energy storage control unit. When the DC fast charging interface is connected to an external DC voltage source, the energy storage battery pack in the energy storage control unit can be quickly charged, so that the stored power of the energy storage battery pack can be charged to a preset value in a shorter time.

[0048] Reference Figure 5In some embodiments, in order to enhance the applicability of the multifunctional low-voltage energy storage device provided by the embodiment of the present invention and meet the user's demand for higher power using DC power supply, the multifunctional low-voltage energy storage device in this embodiment also includes a parallel interface, which is connected in parallel with the AC input interface, and the parallel interface is used to connect to the AC input interface of another multifunctional low-voltage energy storage device. When external AC power is connected, the upper multifunctional low-voltage energy storage device outputs AC power from the parallel interface to the AC input interface of the lower multifunctional low-voltage energy storage device, thereby charging the lower multifunctional low-voltage energy storage device. This realizes that when using an external AC power input, multiple multifunctional low-voltage energy storage devices can be charged at the same time, and after the DC outputs of multiple multifunctional low-voltage energy storage devices are connected in series, high-power DC power supply is provided to the load.

[0049] Reference Figure 6 The specific working process of the multifunctional low-voltage energy storage device proposed in the embodiment of the present invention is described below through a specific embodiment:

[0050] In this embodiment, when AC power is supplied, the manual switch K1 is turned to the AC power output state. At this time, the BMS controller controls the first relay switch KM1 to be in a closed state (the switch state is initially in an open state), and the AC input interface is used to connect to the external AC220V AC power. After passing through the inverter PCS, the inverter PCS outputs the received AC power to the AC power supply interface through the first relay switch KM1, thereby providing AC power to the external load AC220V. At the same time, the inverter PCS also converts the received AC power into DC power to charge the energy storage battery pack PACK; when the external AC power is not connected and AC power needs to be provided to the load, the BMS controller controls the energy storage battery pack PACK to output DC power to the inverter PCS, and the inverter PCS converts the received DC power into AC power and outputs it to the AC power supply interface through the first relay switch KM1, thereby providing AC power to the external load AC220V. When supplying DC power, by turning the manual switch K1 to the DC output state, the BMS controller controls the second relay switch KM2 to be in a closed state, and the BMS controller controls the energy storage battery pack PACK to output DC power through the second relay switch KM2 to the DC power supply interface, thereby providing DC power supply for the external load DC48V; at the same time, the DC fast charging interface can quickly charge the battery pack PACK when connected to an external DC voltage source.

[0051] Reference Figure 7The embodiment of the present invention further provides a low-voltage energy storage system, which includes a first multifunctional low-voltage energy storage device and a second multifunctional low-voltage energy storage device, wherein the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device are both multifunctional low-voltage energy storage devices as described in the above embodiment. In this embodiment, the connection relationship between the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device includes one or more of the following:

[0052] The first multifunctional low-voltage energy storage device is connected to the second multifunctional low-voltage energy storage device via a first connecting line, thereby increasing the AC power storage capacity or DC power storage capacity of the low-voltage energy storage system of the embodiment of the present invention;

[0053] Furthermore, the first multifunctional low-voltage energy storage device is connected to the second multifunctional low-voltage energy storage device via a second connecting line, thereby increasing the DC power supply power of the low-voltage energy storage system of the embodiment of the present invention.

[0054] The low-voltage energy storage system of the embodiment of the present invention solves the technical problems of the energy storage system in the related art that only a single AC power supply or a single DC power supply is provided, the equipment cost is high when the user needs to equip two power supply modes, and the applicability is poor by providing a first multifunctional low-voltage energy storage device and a second multifunctional low-voltage energy storage device.

[0055] The following is a detailed description of a low-voltage energy storage system composed of two multifunctional low-voltage energy storage devices through specific embodiments. Obviously, the low-voltage energy storage system can also be combined with a larger number of multifunctional low-voltage energy storage devices according to needs, which are not listed here:

[0056] Reference Figure 8In some embodiments, the first connecting line is used to connect the AC power supply interface of the first multifunctional low-voltage energy storage device and the AC incoming line interface of the second multifunctional low-voltage energy storage device. Then, when providing AC power to the external load AC220V, the manual switch of the first multifunctional low-voltage energy storage device and the manual switch of the second multifunctional low-voltage energy storage device are both turned to the AC output state, and then the first relay switch KM1 of the first multifunctional low-voltage energy storage device and the first relay switch KM1 of the second multifunctional low-voltage energy storage device are both in a closed state. When the external AC200V is not connected, the power supply of the external load AC220V is jointly supplied by the energy storage battery pack PACK of the first multifunctional low-voltage energy storage device and the energy storage battery pack PACK of the second multifunctional low-voltage energy storage device, thereby increasing the AC power storage capacity of the low-voltage energy storage system and being able to provide a longer power supply for the external load AC220V. Similarly, when providing DC power to an external load AC220V, the manual switches of the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device are both turned to the DC output state. Without external AC200V, the external load DC48V is powered by the energy storage battery pack PACK of the first multifunctional low-voltage energy storage device and the energy storage battery pack PACK of the second multifunctional low-voltage energy storage device, thereby increasing the DC power storage capacity of the low-voltage energy storage system and being able to provide a longer duration of power supply to the external load DC48V.

[0057] Reference Fig. 9 In some embodiments, the second connecting line is used to connect the DC power supply interface of the first multifunctional low-voltage energy storage device and the DC fast charging interface of the second multifunctional low-voltage energy storage device, thereby realizing the combined output of the DC power output by the first multifunctional low-voltage energy storage device and the DC power output by the second multifunctional low-voltage energy storage device, providing DC power supply for a high-power external load, and preventing the DC power output by a single multifunctional low-voltage energy storage device from having a current that is too small to meet the needs of the high-power external load.

[0058] Reference Fig. 9 In some embodiments, in order to realize charging the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device at the same time, the low-voltage energy storage system in this embodiment also includes a third connecting line; the third connecting line is used to connect the parallel interface of the first multifunctional low-voltage energy storage device and the AC input interface of the second multifunctional low-voltage energy storage device, and then when the AC input interface of the first multifunctional low-voltage energy storage device is connected to the external AC power AC220V, the external AC power AC220V can charge the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device at the same time.

[0059] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A multifunctional low-voltage energy storage device, characterized in that: include: A housing, wherein the housing is provided with a cavity, and an AC line interface is embedded in the housing, and the AC line interface is used to connect external AC power; A current transmission conversion unit, fixedly disposed in the cavity, connected to the AC line interface, and used to receive the external AC power; An energy storage control unit, fixedly disposed in the cavity, connected to the current transmission and conversion unit, and configured to receive and store electrical energy, or output direct current to the current transmission and conversion unit; An output switch unit is fixedly disposed in the cavity, wherein the input end of the output switch unit is respectively connected to the output end of the current transmission conversion unit and the charge and discharge interface of the energy storage control unit, and the output end of the output switch unit is respectively connected to the AC power supply interface and the DC power supply interface; The output selection switch is fixedly arranged on the surface of the shell, one end of the output selection switch is connected to the control end of the energy storage control unit, and the other end of the output selection switch is connected to the control end of the output switch unit.

2. The multifunctional low-voltage energy storage device according to claim 1, characterized in that: The energy storage control unit includes an energy storage battery pack and a BMS controller; The BMS controller is connected to the energy storage battery pack and is used to control the charge and discharge state of the energy storage battery pack; The BMS controller is also connected to the output selection switch to control the working state of the output selection switch, and further control the working state of the output switch unit to achieve AC output or DC output.

3. The multifunctional low-voltage energy storage device according to claim 1 or 2, characterized in that ,, the output switch unit includes a first relay switch and a second relay switch; The input end of the first relay is connected to the output end of the current transmission conversion unit, the output end of the first relay is connected to the AC power supply interface, and the control end of the first relay switch is connected to the output selection switch; The input end of the second relay switch is connected to the charging and discharging interface of the energy storage control unit, the output end of the second relay switch is connected to the DC power supply interface, and the start finger end of the second relay switch is connected to the output selection switch.

4. The multifunctional low-voltage energy storage device according to claim 1 or 2, characterized in that: The current transmission conversion unit includes an inverter; The AC input interface of the inverter is connected to the AC line interface, the AC output interface of the inverter is connected to the input end of the output switch unit, and the DC input and output interface of the inverter is connected to the charge and discharge interface of the energy storage control unit.

5. The multifunctional low-voltage energy storage device according to claim 1, characterized in that: The multifunctional low-voltage energy storage device also includes a DC fast charging interface; The DC fast charging interface is embedded in the shell, and the DC fast charging interface is connected to the charging and discharging interface of the energy storage control unit, and is used to connect to an external DC voltage source to charge the energy storage control unit.

6. The multifunctional low-voltage energy storage device according to claim 5, characterized in that: The multifunctional low-voltage energy storage device also includes a parallel connection interface; The parallel interface is embedded in the housing, and is connected in parallel with the AC line interface. The parallel interface is used to connect to the AC line interface of another multifunctional low-voltage energy storage device.

7. A low-voltage energy storage system, characterized in that: The invention comprises a first multifunctional low-voltage energy storage device and a second multifunctional low-voltage energy storage device, wherein the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device are both multifunctional low-voltage energy storage devices according to any one of claims 1 to 6; and the connection relationship between the first multifunctional low-voltage energy storage device and the second multifunctional low-voltage energy storage device includes one or more of the following: The first multifunctional low-voltage energy storage device is connected to the second multifunctional low-voltage energy storage device via a first connecting line to increase the AC power storage capacity or DC power storage capacity of the low-voltage energy storage system; Furthermore, the first multifunctional low-voltage energy storage device is connected to the second multifunctional low-voltage energy storage device via a second connecting line to increase the DC power supply power of the low-voltage energy storage system.

8. The low-voltage energy storage system according to claim 7, characterized in that: The first connecting line is used to connect the AC power supply interface of the first multifunctional low-voltage energy storage device and the AC incoming line interface of the second multifunctional low-voltage energy storage device.

9. The multifunctional low-voltage energy storage system according to claim 7 or 8, characterized in that: The second connecting line is used to connect the DC power supply interface of the first multifunctional low-voltage energy storage device and the DC fast charging interface of the second multifunctional low-voltage energy storage device.

10. The low-voltage energy storage system according to claim 9, characterized in that: It also includes a third connecting line, which is used to connect the parallel interface of the first multifunctional low-voltage energy storage device and the AC input interface of the second multifunctional low-voltage energy storage device.

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