Household energy storage device and system

Abstract

The invention belongs to the technical field of energy storage systems, and particularly relates to a household energy storage device and system.The household energy storage device comprises a plurality of battery modules, each battery module comprises a plurality of battery cells connected in series, a BMS module connected with the battery cells connected in series and a first shell, and the battery cells connected in series and the BMS module are integrated in the first shell; the number of the bidirectional DC / DC modules is the same as that of the battery modules, and each bidirectional DC / DC module is connected with each BMS module; and at least one bidirectional DC / AC module, wherein the bidirectional DC / AC module is connected with the plurality of bidirectional DC / DC modules. The household energy storage device is high in safety and reliability and low in maintenance cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage systems, and in particular relates to a household energy storage device and system. Background Art

[0002] In today's energy transformation context, home energy storage not only brings a lot of convenience to our daily lives, but also plays an important role in improving clean energy utilization and sustainability. The advantages of home energy storage are as follows: ①. Improve the utilization rate of clean energy. Solar photovoltaic power generation is one of the common ways for households to apply renewable energy. Household energy storage batteries are used in conjunction with solar photovoltaic systems to store excess electricity generated by photovoltaic power generation during the day for use at night or on cloudy days, thereby maximizing the use of solar energy. In addition, some households may also combine other renewable energy sources such as small wind power generation systems, in which energy storage batteries play a key role in balancing energy supply and demand. As people's environmental awareness increases, the environmental advantages of household energy storage are becoming increasingly prominent. It can promote the application of renewable energy in households, reduce dependence on traditional fossil energy, reduce carbon emissions, and contribute to the realization of sustainable development goals.

[0003] ②. Dealing with power outage risks. The impact of power outages on family life cannot be ignored, especially in some special circumstances, such as natural disasters and power grid failures. Household energy storage batteries can instantly switch to power supply mode during a power outage, providing continuous power support for families and ensuring basic living needs, such as lighting, refrigerator operation, and communication equipment charging, so that families no longer have to worry about power outages.

[0004] ③. Optimize electricity costs. By making reasonable use of the difference between peak and valley electricity prices, household energy storage batteries can save households electricity expenses. Charging during low electricity price periods and using stored electricity during peak electricity price periods can reduce electricity consumption during peak periods, thereby reducing overall electricity costs. In addition, for households with solar photovoltaic systems installed, energy storage batteries can also store excess photovoltaic power generation, further improving the utilization rate of self-generated electricity and reducing dependence on grid power supply.

[0005] Currently, household energy storage generally has a small capacity. Figure 1 The following figure shows the architecture of a 5 kWh home energy storage system. For home energy storage systems with larger capacity requirements, such as a 10 kWh energy storage system, the industry has two solutions: ①, High voltage series connection scheme. Figure 2For example, for a 10 kWh household energy storage system, the battery can be replaced with 32 strings of batteries in a 5 kWh household energy storage system, and the voltage specifications of the corresponding devices can be increased. However, this solution is not conducive to platform construction and requires large R&D investment. For example, three voltage specifications of BMS modules and three voltage specifications of bidirectional DC / DC modules are required for 5 kWh, 10 kWh, and 15 kWh. Or use the BMS module and bidirectional DC / DC module with a voltage specification of 15 kWh to be compatible with the BMS module and bidirectional DC / DC module of 5 kWh and 10 kWh, but this will increase the cost. In addition, as the battery is used, the battery will gradually age and become inconsistent. During the charging process, one of the 32 lithium batteries in series will reach the overcharge voltage first, resulting in overcharge protection, which will cause the charging of the entire battery group to stop and the entire battery group will not be fully charged; during the discharge process, one of the 32 lithium batteries in series will reach the over-discharge voltage first, resulting in undervoltage protection, which will cause the discharge of the entire battery group to stop and the entire battery group will not be fully discharged. When the battery ages, it needs to be replaced. However, this high-voltage solution with multiple batteries connected in series generally requires replacement of the entire battery, that is, all 32 cells must be replaced, which greatly increases the cost.

[0006] ②, Low voltage parallel solution. Reference Figure 3 and Figure 4 For example, for a 10-kWh household energy storage system, the battery can be changed to a parallel solution of two groups of 16 series battery groups and their BMS modules on a 5-kWh household energy storage system. In this way, when the battery is aged and inconsistent, 16 batteries can be replaced as the minimum unit, reducing the subsequent maintenance costs. However, based on this method, the industry usually connects multiple battery modules in parallel to share a DC / DC module, or makes the battery cell, BMS module, and bidirectional DC / DC module in one module. When multiple battery modules are connected in parallel to share a DC / DC module, the battery modules will charge and discharge each other, bringing the risk of circulation. If the bidirectional DC / DC module and the battery cell are made in one module, the heating of the bidirectional DC / DC module will cause the battery cell temperature to rise, and thermal runaway is one of the important failure forms of the battery system, which will lead to catastrophic accidents. In addition, whether the battery cell or the bidirectional DC / DC module is damaged, the entire group must be replaced. Because these are encapsulated in a module, in order to meet the IPxx protection level requirements, the module is difficult to open or disassemble after processing is completed. Therefore, if the battery cell fails, replacing the entire group will result in a waste of the bidirectional DC / DC module; if the bidirectional DC / DC module fails, replacing the entire group will result in a waste of the battery cell. Summary of the invention

[0007] Based on this, the purpose of the present invention is to provide a household energy storage device and system to fundamentally solve the problem that the existing household energy storage system using low-voltage parallel connection needs to connect multiple battery modules in parallel and share a DC / DC module, resulting in the risk of mutual charging and discharging between the battery modules, or the battery cell, BMS module, and bidirectional DC / DC module are made into one module, resulting in the risk of thermal runaway, and if a failure occurs, the entire group needs to be replaced, which greatly increases the cost.

[0008] The embodiment of the present invention is implemented by providing a household energy storage device, the household energy storage device comprising: A plurality of battery modules, each of which comprises a plurality of battery cells connected in series, a BMS module connected to the plurality of battery cells connected in series, and a first housing, wherein the plurality of battery cells connected in series and the BMS module are integrated in the first housing; a plurality of bidirectional DC / DC modules, the number of the bidirectional DC / DC modules is the same as the number of the battery modules, and each of the bidirectional DC / DC modules is connected to each of the BMS modules respectively; and At least one bidirectional DC / AC module, wherein the bidirectional DC / AC module is connected to a plurality of the bidirectional DC / DC modules.

[0009] In certain embodiments, the household energy storage device further includes a second shell, and the plurality of bidirectional DC / DC modules and at least one bidirectional DC / AC module are integrated in the second shell.

[0010] In some embodiments, the number of the second shell is one.

[0011] In some embodiments, the number of the bidirectional DC / AC module is one, and a plurality of the bidirectional DC / DC modules are all connected to the bidirectional DC / AC module.

[0012] In some embodiments, the number of battery cells in each battery module is n, the number of BMS modules in each battery module is 1, the number of first shells is k, and the number of battery cells included in the household energy storage device is kxn, where k and n are both natural numbers greater than or equal to 1.

[0013] An embodiment of the present invention further provides a household energy storage system, the household energy storage system comprising: A household energy storage device as described in any one of the above embodiments; a load device, the load device being connected to the bidirectional DC / AC module; and A charging device, wherein the charging device is connected to the bidirectional DC / AC module or the bidirectional DC / DC module.

[0014] In some embodiments, the charging device includes a photovoltaic source and an MPPT module connected to the photovoltaic source, and the MPPT module is connected to the bidirectional DC / DC module.

[0015] In certain embodiments, the charging device includes a photovoltaic source and an MPPT module connected to the photovoltaic source.

[0016] A household energy storage device provided in an embodiment of the present invention includes multiple battery modules, multiple bidirectional DC / DC modules and at least one bidirectional DC / AC module, each battery module includes multiple battery cells connected in series, a BMS module connected to the multiple battery cells connected in series and a first shell, the multiple battery cells connected in series and the BMS module are integrated in the first shell, the number of bidirectional DC / DC modules is the same as the number of battery modules, and each bidirectional DC / DC module is respectively connected to each BMS module, and the bidirectional DC / AC module is connected to multiple bidirectional DC / DC modules. After the battery modules are connected in parallel, they are respectively connected to a bidirectional DC / DC module. There is no mutual charging and discharging between the battery modules, thus avoiding the risk of circulating current. The battery module and the bidirectional DC / DC module are independently arranged, and the heating of the bidirectional DC / DC module will not affect the battery module, thus effectively avoiding the occurrence of thermal runaway. The charging and discharging of each battery module can be carried out independently, and individual control and management can be achieved, so there will be no circulating current phenomenon of mutual charging and discharging between the battery modules, thereby greatly improving the safety and reliability of the device. In addition, if the battery module, bidirectional DC / DC module, or bidirectional DC / AC module is damaged, it can be replaced separately, without causing the need to replace other undamaged components during replacement, thereby effectively reducing the maintenance cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a structural block diagram of a 5 kWh household energy storage system provided by existing technology; Figure 2 It is a structural block diagram of a 10 kWh household energy storage system using a high voltage series connection provided by the prior art; Figure 3 and Figure 4 It is a structural block diagram of a 10 kWh household energy storage system using a low voltage parallel connection method provided by the prior art; Figure 5 is a structural block diagram of a household energy storage device provided in an embodiment of the present invention; Figure 6 It is a structural block diagram of a household energy storage system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0019] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0021] refer to Figure 5 , an embodiment of the present invention provides a household energy storage device, the household energy storage device comprising: A plurality of battery modules, each of which comprises a plurality of battery cells 11 connected in series, a BMS module 12 connected to the plurality of battery cells 11 connected in series, and a first housing 10, wherein the plurality of battery cells 11 connected in series and the BMS module 12 are integrated in the first housing 10; a plurality of bidirectional DC / DC modules 21, wherein the number of the bidirectional DC / DC modules 21 is the same as the number of the battery modules, and each of the bidirectional DC / DC modules 21 is respectively connected to each of the BMS modules 12; and At least one bidirectional DC / AC module 22 , wherein the bidirectional DC / AC module 22 is connected to the plurality of bidirectional DC / DC modules 21 .

[0022] The battery cell 11 is a core component of the battery module and is a basic electrochemical unit that can convert chemical energy into electrical energy or perform a reverse electrical energy storage process through a chemical reaction. For example, the common lithium-ion battery cell 11 is mainly composed of a positive electrode, a negative electrode, a diaphragm, and an electrolyte. The positive and negative electrode materials are the key to the electrochemical reaction. The diaphragm separates the positive and negative electrodes to prevent short circuits and allow ions to pass through. The electrolyte provides a medium for ion transmission to ensure the smooth progress of the electrochemical reaction. In the present invention, the battery cell 11 is not limited to a specific material, as long as it can realize the function of converting chemical energy into electrical energy or performing a reverse electrical energy storage.

[0023] The BMS module 12 is the battery management system, which is a system for monitoring and controlling the battery module. It mainly includes the following parts: the main control unit, which is usually a microcontroller (MCU) or a microprocessor (MPU), which is equivalent to the "brain" of the entire BMS module 12, and is responsible for receiving data collected by various sensors, running various state estimation and control algorithms, coordinating the work of various parts, and communicating with external devices. The acquisition unit, which is composed of a voltage acquisition circuit, a current acquisition circuit, a temperature acquisition circuit, etc., is responsible for converting the key parameters of the battery module into electrical signals that can be recognized and processed by the main control unit to ensure that the collected data is accurate and reliable. The balancing circuit is a specific circuit module that realizes the balancing function of the battery module. The circuit structure varies according to the balancing method (active balancing or passive balancing), but its purpose is to adjust the power and voltage differences of the battery module. The communication interface has a variety of communication interfaces, such as CAN bus interface, RS485 interface, SPI interface or I2C interface, etc., which is convenient for exchanging data with external systems. The protection circuit is composed of various switch devices (such as relays, MOSFET, etc.), fuses, etc. When the battery module is detected to be overcharged, over-discharged, over-heated, short-circuited, etc., it can quickly act to cut off the relevant circuits to achieve safety protection of the battery module. In the present invention, the specific circuit structure of the BMS module 12 is not limited as long as it can achieve the corresponding functions of battery module management.

[0024] The DC / DC module is a DC-to-DC module that can convert the input DC power into DC power output of different voltage levels. It is divided into buck type (Buck), boost type (Boost), and buck-boost type (Buck-Boost). For the buck type, when the switch is turned on, the input voltage is applied to the inductor and the load, the inductor stores energy, and the current rises; when the switch is turned off, the inductor releases energy to the load through the diode to maintain the load current. By controlling the duty cycle of the switch, the output voltage can be adjusted to achieve the buck function. For the boost type, when the switch is turned on, the input voltage charges the inductor to store energy; when the switch is turned off, the induced electromotive force generated by the inductor is superimposed on the input voltage, and the capacitor is charged and the load is powered through the diode, thereby increasing the output voltage. The output voltage can also be adjusted by controlling the duty cycle. For the buck-boost type, the principles of buck and boost are combined to achieve an output voltage that can be higher or lower than the input voltage. The bidirectional DC / DC module 21 refers to a bidirectional DC / DC module. For example, in this embodiment, power can flow from one side of the battery module through the bidirectional DC / DC module 21 to one side of the bidirectional DC / AC module 22, or from one side of the bidirectional DC / AC module 22 to one side of the battery module through the bidirectional DC / DC module 21. In the present invention, the specific circuit structure of the bidirectional DC / DC module 21 is not limited, as long as the corresponding functions of the bidirectional DC / DC module can be realized.

[0025] The DC / AC module is a DC to AC module, and its basic principle is to use power electronic conversion technology to convert DC power into AC power through an inverter circuit. The inverter circuit generally includes power switching devices (such as insulated gate bipolar transistors IGBT, metal oxide semiconductor field effect transistors MOSFET, etc.). According to a certain control strategy, these switching devices are continuously turned on and off, so as to chop and synthesize the input DC voltage and output AC power. The bidirectional DC / AC module 22 refers to a DC / AC module with bidirectional flow. For example, in this embodiment, it flows from the battery module side through the bidirectional DC / AC module 22 to the load device 30 side, and it can also flow from the charging device 40 side through the bidirectional DC / AC module 22 to the battery module side. In the present invention, the specific circuit structure of the bidirectional DC / AC module 22 is not limited, as long as the corresponding functions of the DC / AC module with bidirectional flow can be realized.

[0026] Each battery module includes a plurality of battery cells 11, a BMS module 12 and a first shell 10. The plurality of battery cells 11 are connected in series, and the plurality of battery cells 11 connected in series are connected to the BMS module 12. The plurality of battery cells 11 and the BMS module 12 are integrated in the first shell 10. When a household energy storage device with different power capacity specifications is required, a unitized design can be performed, and the number of battery modules can be increased or decreased accordingly (the number of bidirectional DC / DC modules 21 can be increased or decreased accordingly), so as to prepare household energy storage devices with different power capacity specifications to meet the needs of different application scenarios and achieve application expansion. In addition, the first shell 10 can also provide a certain degree of protection for the integrated battery cells 11 and the BMS module 12.

[0027] The bidirectional DC / DC module 21 is a bidirectional DC / DC circuit board, and the bidirectional DC / AC module 22 is a bidirectional DC / AC circuit board. When the battery module is discharged, the voltage and current of the battery module flow through the bidirectional DC / DC module 21, are converted into high-voltage direct current, and then flow through the bidirectional DC / AC module 22, and are inverted into alternating current to be provided to the load device 30 for use. When the battery module is charged, the charging device 40 flows through the bidirectional DC / AC module 22, is converted into high-voltage direct current, and then flows through the bidirectional DC / DC module 21, and is converted into the voltage and current required by the battery module to be provided to the battery module for charging; or the charging device 40 flows through the bidirectional DC / DC module 21, and is converted into the voltage and current required by the battery module to be provided to the battery module for charging.

[0028] The number of battery modules and bidirectional DC / DC modules 21 is the same, and they cooperate with each other to form a group, that is, when the battery module is discharged, the voltage and current of the battery module flow through the corresponding bidirectional DC / DC module 21 connected thereto. When the battery module is charged, the voltage and current of the bidirectional DC / DC module 21 flow through the corresponding battery module connected thereto. Specifically, the BMS module 12 of the battery module is connected to the bidirectional DC / DC module 21, and the battery cell 11 of the non-battery module is connected to the bidirectional DC / DC module 21. Only in this way can the battery control function of the BMS module 12 be realized.

[0029] In some embodiments, the capacity of each battery cell 11 is in the range of 100Ah to 300Ah. In some embodiments, the capacity of each battery cell 11 is 100Ah.

[0030] In some embodiments, the first housing 10 is made of metal or plastic. The metal material is, for example, conductive silver, aluminum, iron, etc. The plastic material is not conductive, but can be connected by wires to achieve conductivity between components, and the cost of plastic is lower than that of metal.

[0031] In the household energy storage device provided by the present invention, it includes multiple battery modules, multiple bidirectional DC / DC modules 21 and at least one bidirectional DC / AC module 22. Each battery module includes multiple battery cells 11 connected in series, a BMS module 12 connected to the multiple battery cells 11 connected in series, and a first shell 10. The multiple battery cells 11 connected in series and the BMS module 12 are integrated in the first shell 10. The number of bidirectional DC / DC modules 21 is the same as the number of battery modules, and each bidirectional DC / DC module 21 is respectively connected to each BMS module 12. The bidirectional DC / AC module 22 connects multiple bidirectional DC / DC modules 21. After the battery modules are connected in parallel, they are respectively connected to a bidirectional DC / DC module 21. There is no mutual charging and discharging between the battery modules, thus avoiding the risk of circulating current. The battery module and the bidirectional DC / DC module 21 are independently arranged, and the heating of the bidirectional DC / DC module 21 will not affect the battery module, thus effectively avoiding the occurrence of thermal runaway. The charging and discharging of each battery module can be carried out independently, and individual control and management can be achieved, so there will be no circulating current phenomenon of mutual charging and discharging between the battery modules, thereby greatly improving the safety and reliability of the device. In addition, if the battery module, the bidirectional DC / DC module 21, and the bidirectional DC / AC module 22 are damaged, they can be replaced separately, without causing the need to replace the remaining undamaged components during replacement, thereby effectively reducing the maintenance cost of the device.

[0032] refer to Figure 5 In some specific embodiments of the present invention, the household energy storage device further includes a second shell 20 , in which a plurality of the bidirectional DC / DC modules 21 and at least one bidirectional DC / AC module 22 are integrated.

[0033] Multiple bidirectional DC / DC modules 21 and at least one bidirectional DC / AC module 22 are integrated in the second housing 20. In some embodiments, each bidirectional DC / DC module 21 and bidirectional DC / AC can be independently disassembled and independently installed. In some embodiments, by disassembling and installing the second housing 20, the overall disassembly and installation of multiple bidirectional DC / DC modules 21 and at least one bidirectional DC / AC module 22 are achieved. The second housing 20 can provide a certain protection for the integrated bidirectional DC / DC modules 21 and bidirectional DC / AC modules 22.

[0034] In some embodiments, the second housing 20 is made of metal or plastic. The metal material is, for example, conductive silver, aluminum, iron, etc. The plastic material is not conductive, but can be connected by wires to achieve conductivity between components, and the cost of plastic is lower than that of metal.

[0035] refer to Figure 5In some specific embodiments of the present invention, the number of the second housing 20 is one. A plurality of bidirectional DC / DC modules 21 and at least one bidirectional DC / AC module 22 are integrated in the second housing 20 .

[0036] refer to Figure 5 In some specific embodiments of the present invention, the number of the bidirectional DC / AC module 22 is one, and a plurality of the bidirectional DC / DC modules 21 are connected to the bidirectional DC / AC module 22 .

[0037] In this embodiment, multiple bidirectional DC / DC modules 21 are connected to bidirectional DC / AC modules 22. Each bidirectional DC / DC module 21 is connected to a battery module, and the electricity transmitted from each battery module to each bidirectional DC / DC module 21 is transmitted to the bidirectional DC / AC module 22, inverted into AC power by the bidirectional DC / AC module 22, and then transmitted to the load device 30; during charging, if the charging device 40 is connected to the bidirectional DC / AC module 22, the electricity of the charging device 40 is transmitted to the bidirectional DC / AC module 22, then passes through each bidirectional DC / DC module 21, and finally transmitted to each battery module.

[0038] refer to Figure 5 In some specific embodiments of the present invention, the number of the battery cells 11 of each battery module is n, the number of the BMS modules 12 of each battery module is 1, the number of the first shells 10 is k, and the number of the battery cells 11 included in the household energy storage device is kxn, where k and n are both natural numbers greater than or equal to 1.

[0039] For example, the number of the battery cells 11 of each battery module is 15, 16, 30, 32, 45 or 48, and the number of the BMS module 12 of each battery module is 1. If the number of the first shells 10 is 2, the number of the battery cells 11 included in the household energy storage device is 30, 32, 60, 64, 90 or 96; if the number of the first shells 10 is 3, the number of the battery cells 11 included in the household energy storage device is 45, 48, 90, 96, 135 or 144.

[0040] In some embodiments, the number of cells 11 in each battery module is 16. Although the figure shows 16 strings, 16 and 16 strings refer to the same meaning. In addition, to avoid ambiguity, it should be noted that Figure 5 and Figure 6 The 16 strings shown refer to a total of 16 strings of battery cells 11 , rather than 16 strings of battery cells 11 plus 2 strings of illustrated battery cells 11 .

[0041] In this embodiment, the number of BMS modules 12 in each battery module is 1, and each BMS module 12 can control multiple battery cells 11 connected thereto. For example, if the number of battery cells 11 is 16, and the 16 battery cells 11 are connected in series, each BMS module 12 can control the 16 battery cells 11 connected thereto.

[0042] refer to Figure 6 , an embodiment of the present invention further provides a household energy storage system, the household energy storage system comprising: A household energy storage device as described in any one of the above embodiments; a load device 30 connected to the bidirectional DC / AC module 22; and A charging device 40 , wherein the charging device 40 is connected to the bidirectional DC / AC module 22 or the bidirectional DC / DC module 21 .

[0043] When the battery module is discharged, the voltage and current of the battery module flows through the bidirectional DC / DC module 21, is converted into high-voltage direct current, and then flows through the bidirectional DC / AC module 22, is inverted into alternating current, and is provided to the load device 30. When the battery module is charged, the charging device 40 flows through the bidirectional DC / AC module 22, is converted into high-voltage direct current, and then flows through the bidirectional DC / DC module 21, is converted into the voltage and current required by the battery module, and is provided to the battery module for charging; or the charging device 40 flows through the bidirectional DC / DC module 21, is converted into the voltage and current required by the battery module, and is provided to the battery module for charging.

[0044] In this embodiment, the household energy storage system includes a household energy storage device, which includes multiple battery modules, multiple bidirectional DC / DC modules 21 and at least one bidirectional DC / AC module 22. Each battery module includes multiple battery cells 11 connected in series, a BMS module 12 connected to the multiple battery cells 11 connected in series, and a first shell 10. The multiple battery cells 11 connected in series and the BMS module 12 are integrated in the first shell 10. The number of bidirectional DC / DC modules 21 is the same as the number of battery modules, and each bidirectional DC / DC module 21 is respectively connected to each BMS module 12. The bidirectional DC / AC module 22 connects multiple bidirectional DC / DC modules 21. After the battery modules are connected in parallel, they are respectively connected to a bidirectional DC / DC module 21. There is no mutual charging and discharging between the battery modules, thus avoiding the risk of circulating current. The battery module and the bidirectional DC / DC module 21 are independently arranged, and the heating of the bidirectional DC / DC module 21 will not affect the battery module, thus effectively avoiding the occurrence of thermal runaway. The charging and discharging of each battery module can be carried out independently, and individual control and management can be achieved, so there will be no circulating current phenomenon of mutual charging and discharging between the battery modules, thereby greatly improving the safety and reliability of the device. In addition, if the battery module, the bidirectional DC / DC module 21, and the bidirectional DC / AC module 22 are damaged, they can be replaced separately, without causing the need to replace the remaining undamaged components during replacement, thereby effectively reducing the maintenance cost of the device.

[0045] refer to Figure 6 In some specific embodiments of the present invention, the charging device 40 includes a photovoltaic source 41 and an MPPT module 42 connected to the photovoltaic source 41 , and the MPPT module 42 is connected to the bidirectional DC / DC module 21 .

[0046] The MPPT module 42, whose full name is Maximum Power Point Tracking module, is an electrical module that plays an important role in photovoltaic systems. The MPPT module 42 monitors the voltage and current output of the solar panel in real time, and uses a specific algorithm to adjust the load impedance of the panel, so as to find and track the working point that can make the solar panel output the maximum power. Commonly used MPPT control algorithms include perturbation observation method, incremental conductance method, constant voltage tracking method, etc. For example, the perturbation observation method periodically changes the load impedance and observes the change in power. If the power increases, the impedance continues to change in the same direction, otherwise it changes direction, and repeats this process, eventually stabilizing the system near the maximum power point. In the present invention, the specific circuit structure of the MPPT module 42 is not limited, as long as it can realize the corresponding function of tracking the maximum power point in the photovoltaic system.

[0047] When the battery module is charged, the photovoltaic source 41 transmits electricity to the bidirectional DC / DC module 21 through the MPPT module 42, and converts it into the voltage and current required by the battery module to provide charging for the battery module. During the charging process, the MPPT module 42 tracks the maximum power point to maintain the maximum power, thereby ensuring the charging efficiency.

[0048] In some embodiments, the battery module can also be charged by using external AC power as the charging device 40. Specifically, the external AC current is converted into high-voltage DC power by the bidirectional DC / AC module 22, and then flows through the bidirectional DC / DC module 21 to be converted into the voltage and current required by the battery module to provide the battery module for charging.

[0049] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0050] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A household energy storage device, characterized in that: The household energy storage device comprises: A plurality of battery modules, each of which comprises a plurality of battery cells connected in series, a BMS module connected to the plurality of battery cells connected in series, and a first housing, wherein the plurality of battery cells connected in series and the BMS module are integrated in the first housing; a plurality of bidirectional DC / DC modules, the number of the bidirectional DC / DC modules is the same as the number of the battery modules, and each of the bidirectional DC / DC modules is connected to each of the BMS modules respectively; and At least one bidirectional DC / AC module, wherein the bidirectional DC / AC module is connected to a plurality of the bidirectional DC / DC modules.

2. The household energy storage device according to claim 1, characterized in that: The household energy storage device further includes a second shell, in which the plurality of bidirectional DC / DC modules and at least one bidirectional DC / AC module are integrated.

3. The household energy storage device according to claim 2, characterized in that: The number of the second shell is one.

4. The household energy storage device according to claim 2, characterized in that: The number of the bidirectional DC / AC module is one, and a plurality of the bidirectional DC / DC modules are all connected to the bidirectional DC / AC module.

5. The household energy storage device according to claim 1, characterized in that: The number of battery cells in each battery module is n, the number of BMS modules in each battery module is 1, the number of first shells is k, and the number of battery cells included in the household energy storage device is kxn, where k and n are both natural numbers greater than or equal to 1.

6. A household energy storage system, characterized in that: The household energy storage system comprises: A household energy storage device as described in any one of claims 1 to 5; a load device, the load device being connected to the bidirectional DC / AC module; and A charging device, wherein the charging device is connected to the bidirectional DC / AC module or the bidirectional DC / DC module.

7. The household energy storage system according to claim 6, characterized in that: The charging device includes a photovoltaic source and an MPPT module connected to the photovoltaic source, and the MPPT module is connected to the bidirectional DC / DC module.

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