Integral photovoltaic energy storage assembly

Abstract

The invention relates to an integral type photovoltaic energy storage assembly, belongs to the field of solar photovoltaic power generation, and aims to solve the problems that an existing photovoltaic energy storage product is complex in structure and installation, high in cost, low in efficiency and high in safety risk. The integrated photovoltaic energy storage assembly comprises a solar cell panel, an alternating current and direct current multidirectional conversion device and an energy storage battery. The AC-DC multidirectional conversion device and the energy storage battery are installed on the back surface of the solar cell panel, and the extension height does not exceed the back side end surface of the frame of the solar cell panel. The alternating current and direct current multidirectional conversion device comprises three groups of connecting ends, a plurality of voltage converters, a plurality of switch elements and a control chip, the three groups of connecting ends are electrically connected to a solar cell panel, an energy storage battery and an alternating current power grid respectively, and the control chip is configured to selectively switch on at least one switch element in different working modes of the integral photovoltaic energy storage assembly so as to control the three groups of connecting ends. A voltage conversion path is established between the respective two sets of connection terminals by means of at least one voltage converter.

Description

Technical Field

[0001] The present invention relates to the field of solar photovoltaic power generation, and more specifically to an integrated photovoltaic energy storage component that integrates photovoltaic power generation, energy storage and power conversion equipment (or converter equipment). Background Art

[0002] With the increase of global energy demand and the concern for environmental protection, solar photovoltaic power generation has been increasingly developed and applied as a renewable clean energy technology. Photovoltaic power generation technology uses photovoltaic cell modules to convert solar energy into electrical energy and supply power to the power grid or power loads. In order to solve the intermittent and volatile problems of solar power generation, photovoltaic power generation is generally combined with photovoltaic energy storage to form a photovoltaic power generation and energy storage system.

[0003] However, current photovoltaic power generation and energy storage power stations are often in an independent operation state, that is, the direct current generated by photovoltaic cell modules or solar panels is first converted into alternating current through an inverter and then combined with the direct current energy storage battery through a converter, so that the electric energy undergoes multiple conversions and the efficiency is greatly reduced.

[0004] The string inverter equipped for each photovoltaic string is a commonly used photovoltaic inverter at present. It has Maximum Power Point Tracking (MPPT) on the DC side and is connected to the grid in parallel on the AC side. However, the string inverter does not have the single-board MPPT adjustment function, has a short board effect, and has relatively low efficiency. In addition, the string inverter will be subjected to DC high voltage, and there is also the problem of long-distance DC high voltage transmission. After long-term use and aging, it is easy to cause DC arc and cause safety hazards such as fire. Although it is now possible to improve MPPT and cut off DC high voltage after a fire by adding optimizers and circuit breakers, which is conducive to eliminating the problem of electric shock for firefighters during rescue, the root cause of long-distance DC high voltage has not been solved, the probability of fire is still very high, and adding circuit breakers and optimizers does not have an advantage in terms of cost.

[0005] Compared with string inverters, traditional micro inverters (micro inverters) solve the problem that long-distance DC high-voltage transmission is prone to cause DC arcs and fire hazards, and can realize MPPT adjustment of a single solar panel, avoiding the short board effect of string inverters, but the cost per watt is high and the installation is complicated - it is necessary to install micro inverters one by one on the track before installing solar panels, and then connect solar panels and micro inverters, which will greatly increase the installation cost (especially in harsh outdoor high-altitude installation environments). In addition, the combination with the energy storage system requires the configuration of a separate inverter, which makes the system complex and the cost rises significantly. There is also the problem of low efficiency caused by multiple conversions of electric energy.

[0006] In addition, in the current form of photovoltaic power generation and energy storage products, photovoltaic modules, inverters and energy storage batteries are independent products. Customers can only purchase each product separately and then rely on professional installers to combine the products. This not only greatly increases the cost of customer acquisition, but also greatly reduces the convenience of product acquisition. Customers can only obtain non-standard customized product combinations from qualified channel dealers. The products lack versatility and ease of use. The costs of sales, transportation, installation and maintenance are very high. There are also great construction risks and safety hazards in use. Summary of the invention

[0007] The object of the present invention is to solve at least one of the above problems and / or other defects in the prior art.

[0008] The present invention provides an integrated photovoltaic energy storage component, which includes a solar panel, an AC / DC multidirectional conversion device and an energy storage battery. The solar panel is equipped with a frame extending toward the back side thereof, and the AC / DC multidirectional conversion device and the energy storage battery are installed on the back side of the solar panel and the extension height does not exceed the back side end face of the frame. The AC / DC multidirectional conversion device includes three groups of connection terminals, a plurality of voltage converters, a plurality of switch elements and a control chip. The three groups of connection terminals are electrically connected to the solar panel, the energy storage battery and the AC power grid respectively. Each switch element is configured to electrically connect a corresponding one of the plurality of voltage converters with another converter of the plurality of voltage converters, or to electrically connect a corresponding one of the three groups of connection terminals. The control chip is configured to selectively connect at least one of the plurality of switch elements in different working modes of the integrated photovoltaic energy storage component, so as to establish a voltage conversion path between corresponding two of the three groups of connection terminals with the help of at least one of the plurality of voltage converters.

[0009] According to an exemplary configuration of the present invention, in the above-mentioned integrated photovoltaic energy storage assembly, the AC / DC multi-directional conversion device and the energy storage battery can be installed on the back of the solar panel by an integrated lattice-shaped bracket fixed to the frame within the frame.

[0010] According to an exemplary configuration of the present invention, in an integrated photovoltaic energy storage assembly as described in any of the above items, the energy storage battery may include a battery module composed of a plurality of blade batteries, a plurality of soft-pack batteries or a plurality of solid-state batteries.

[0011] According to an exemplary configuration of the present invention, in any of the above-described integrated photovoltaic energy storage components, the integrated photovoltaic energy storage component may further include a battery management system that is integrated in the AC / DC multi-directional conversion device or is separately provided from the AC / DC multi-directional conversion device.

[0012] According to an exemplary configuration of the present invention, in the integrated photovoltaic energy storage assembly as described in any of the above items, the multiple voltage converters include a first DC / DC converter, a second DC / DC converter and a bidirectional AC / DC converter, wherein the input side of the first DC / DC converter is electrically connected to the solar panel, the input side of the second DC / DC converter is electrically connected to the energy storage battery, and the AC side of the bidirectional AC / DC converter is electrically connected to the AC grid; the multiple switch elements include first to third switch elements, wherein the first switch element is assigned to the first DC / DC converter, the second switch element is assigned to the second DC / DC converter, and the third switch element is assigned to the bidirectional AC / DC converter, wherein the control chip is further configured to selectively connect corresponding two switch elements of the first to third switch elements, so as to realize different working modes of the integrated photovoltaic energy storage assembly with the help of the first DC / DC converter, the second DC / DC converter and the corresponding two converters of the bidirectional AC / DC converter.

[0013] According to an exemplary configuration of the present invention, in the integrated photovoltaic energy storage assembly as described in any of the above items, the working modes of the integrated photovoltaic energy storage assembly may include a solar power supply mode, a DC charging mode, an AC charging mode and a battery power supply mode, wherein the control chip may be further configured to: in the solar power supply mode, turn on the first and third switching elements and make the bidirectional AC / DC converter work in an inverter state, so as to convert the first DC power from the solar panel into the first AC power for supplying power to the AC power grid with the help of the first DC / DC converter and the bidirectional AC / DC converter; in the DC charging mode, turn on the first and second switching elements, so as to make the first DC / DC converter work in an inverter state, so as to convert the first DC power from the solar panel into the first AC power for supplying power to the AC power grid with the help of the first DC / DC converter; and the second DC / DC converter converts the first direct current from the solar panel into the second direct current for charging the energy storage battery; in the AC charging mode, the second and third switching elements are turned on and the bidirectional AC / DC converter is operated in a rectifying state, so as to convert the first alternating current from the AC power grid into the second direct current for charging the energy storage battery with the help of the bidirectional AC / DC converter and the second DC / DC converter; and in the battery power supply mode, the second and third switching elements are turned on and the bidirectional AC / DC converter is operated in an inversion state, so as to convert the second direct current from the energy storage battery into the first alternating current for powering the AC power grid with the help of the second DC / DC converter and the bidirectional AC / DC converter.

[0014] According to an exemplary configuration of the present invention, in any of the above integrated photovoltaic energy storage components, the first and second DC / DC converters may each be implemented as any one of a Boost circuit, a Buck circuit, and a Boost-Buck circuit.

[0015] According to an exemplary configuration of the present invention, in an integrated photovoltaic energy storage assembly as described in any of the above items, the Boost-Buck step-up and step-down circuit may include a first switch tube arranged at the input side of the corresponding DC / DC converter, a second switch tube arranged at the output side of the corresponding DC / DC converter, and an energy storage inductor arranged between the first switch tube and the second switch tube, wherein the control chip may be configured to control the duty cycle of the first and second switch tubes based on the output voltage of the solar panel and the charging voltage of the energy storage battery, so that the corresponding DC / DC converter operates in a boost mode or a buck mode.

[0016] According to an exemplary configuration of the present invention, in the integrated photovoltaic energy storage assembly as described in any one of the above items, the first and second DC / DC converters may each include a first capacitor module, and the first capacitor module is composed of at least one electrolytic capacitor and at least one chip capacitor.

[0017] According to an exemplary configuration of the present invention, in the integrated photovoltaic energy storage assembly as described in any one of the above items, the capacity of each electrolytic capacitor is 800μF-3000μF, the capacity of each chip capacitor is 1-10μF, and the diameter of each electrolytic capacitor is less than 17mm.

[0018] According to an exemplary configuration of the present invention, in an integrated photovoltaic energy storage component as described in any of the above items, the bidirectional AC / DC converter may include an inductor, an isolation transformer, a first switching circuit and a second switching circuit, wherein the input side of the first switching circuit is electrically connected to the DC side of the bidirectional AC / DC converter, the inductor is arranged between the secondary side of the isolation transformer and the input side of the second switching circuit, and the output side of the second switching circuit is electrically connected to the AC side of the bidirectional AC / DC converter, wherein the first and second switching circuits respectively adopt a full-bridge topology structure, the four bridge arms of the first switching circuit are respectively composed of a single switch tube, the first upper bridge arm and the first lower bridge arm of the second switching circuit are respectively composed of two switch tubes connected in series in a back-to-back manner, and the second upper bridge arm and the second lower bridge arm of the second switching circuit are respectively composed of a single capacitor.

[0019] According to an exemplary configuration of the present invention, in an integrated photovoltaic energy storage assembly as described in any of the above items, when the isolation transformer is in the frequency range of 8KHz to 300KHz, the number of turns of the primary coil of the isolation transformer is set to 3 to 6 turns, the number of turns of the secondary coil is set to 9 to 18 turns, the turns ratio is set to between 2 and 4, the primary inductance is between 50μH and 1.5mH, the secondary leakage inductance is between 5μH and 200μH, and the height of the isolation transformer is set to less than 17mm.

[0020] According to an exemplary configuration of the present invention, in an integrated photovoltaic energy storage assembly as described in any of the above items, the bidirectional AC / DC converter may also include a second capacitor module arranged between the second switching circuit and the AC power grid, and the second capacitor module is composed of 1 to 3 safety capacitors with a height of less than 17 mm.

[0021] According to an exemplary configuration of the present invention, in an integrated photovoltaic energy storage assembly as described in any of the above items, the bidirectional AC / DC converter may include a bidirectional full-bridge converter composed of four switching tubes and an LC resonator, the DC side of the bidirectional full-bridge converter is electrically connected to the second end of the third switching element, and the LC resonator is arranged between the AC side of the bidirectional full-bridge converter and the AC power grid.

[0022] According to an exemplary configuration of the present invention, in the integrated photovoltaic energy storage assembly as described in any of the above items, the bidirectional AC / DC converter may also include a third capacitor module arranged between the LC resonator and the AC power grid, and the third capacitor module is composed of 1 to 3 safety capacitors with a height of less than 17 mm.

[0023] The integrated photovoltaic energy storage assembly according to the present invention has at least the following beneficial effects: 1. The integrated photovoltaic energy storage component integrates photovoltaic power generation, energy storage and power conversion equipment into an organic whole, realizing the integration of function and structure. In this way, the realization of photovoltaic energy storage products is simplified. Compared with the traditional photovoltaic components, inverters and energy storage units that are separated, users do not need to purchase these devices separately, nor do they need professional qualified personnel to match and install these devices separately. The complex customized design configuration has become a simple component selection, which greatly reduces the user's purchase and use threshold, brings great convenience to transportation, installation and maintenance, and greatly reduces the labor cost of transportation, installation and maintenance of photovoltaic energy storage products. The integrated integrated photovoltaic energy storage component does not increase the volume or change the appearance on the basis of a single solar panel, which is also conducive to the storage, transportation and installation of photovoltaic energy storage products.

[0024] 2. The single solar panel in the integrated photovoltaic energy storage component directly realizes conversion, energy storage and grid connection through the DC end. Its DC stage always works at a low voltage state of less than 80V, which completely eliminates the risk of arcing in the circuit of the DC high voltage string inverter and traditional energy storage power station when working for a long time and aging. It can greatly reduce the probability of fire in the photovoltaic energy storage power station, and the safety is much better than the traditional conversion, energy storage and grid connection scheme.

[0025] 3. The AC / DC multi-directional conversion device in the integrated photovoltaic energy storage component directly charges the electrical energy into the energy storage battery through a DC converter. Compared with the traditional photovoltaic energy storage component that converts the electrical energy into AC power and then rectifies the AC power into DC power to charge the energy storage battery, it reduces the two conversion processes from DC to AC and then from AC to DC, and the conversion efficiency is greatly improved.

[0026] 4. The AC / DC multi-directional conversion device in the integrated photovoltaic energy storage component integrates various power conversion functions such as DC step-up and step-down conversion and AC / DC conversion, and can automatically switch and adapt to different working modes according to the power demand, light conditions and grid status at different time periods: (1) photovoltaic power generation grid-connected power supply, power storage, and power supply to loads; (2) energy storage power grid-connected power supply and power supply to loads; (3) grid power generation device charging energy storage batteries, etc. Compared with traditional solar power stations and energy storage power stations, the power dispatching and distribution switching between them requires multiple authorizations from the grid and the owner, long-distance transmission, and consideration of complex grid-connected interest games. The present invention has obvious advantages in terms of dispatching efficiency, convenience, and transmission loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The features and advantages of the present invention will be clearly understood through the detailed description provided below with reference to the accompanying drawings. It should be understood that the following drawings are only schematic and not necessarily drawn to scale, and thus cannot be regarded as limiting the present invention, wherein: Figure 1 An overall schematic diagram of the connection between the integrated photovoltaic energy storage assembly according to the present invention and the power grid is shown.

[0028] Figure 2-1 A rear view of an integrated photovoltaic energy storage assembly according to a first exemplary embodiment of the present invention is shown.

[0029] Figure 2-2 A cross-sectional view of an integrated photovoltaic energy storage assembly according to a first exemplary embodiment of the present invention is shown.

[0030] Figure 3-1 A rear view of an integrated photovoltaic energy storage assembly according to a second exemplary embodiment of the present invention is shown.

[0031] Figure 3-2A cross-sectional view of an integrated photovoltaic energy storage assembly according to a second exemplary embodiment of the present invention is shown.

[0032] Figure 4 The internal structure diagram of an AC / DC multi-directional conversion device in an integrated photovoltaic energy storage assembly according to an exemplary embodiment of the present invention is shown.

[0033] Figure 5-1 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the solar power supply mode is shown.

[0034] Figure 5-2 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the DC charging mode is shown.

[0035] Figure 5-3 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the AC charging mode is shown.

[0036] Figure 5-4 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the battery power supply mode is shown.

[0037] Figure 6 A schematic diagram showing an output voltage waveform of a solar panel in an integrated photovoltaic energy storage assembly according to the present invention.

[0038] Figure 7-1 An internal circuit diagram of a first or second DC / DC converter implemented as a Boost circuit is shown.

[0039] Figure 7-2 An internal circuit diagram of the first or second DC / DC converter implemented as a Buck step-down circuit is shown.

[0040] Figure 7-3 An internal circuit diagram of a first or second DC / DC converter implemented as a Boost-Buck step-up / step-down circuit is shown.

[0041] Figure 8-1 A schematic diagram showing the internal circuit structure of a bidirectional AC / DC converter using an isolated transformer structure is shown.

[0042] Figure 8-2 A schematic diagram showing the internal circuit structure of a bidirectional AC / DC converter using a non-isolated transformer structure. DETAILED DESCRIPTION

[0043] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, many specific details are set forth so that those skilled in the art can more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that the present invention may be implemented without some of these specific details. In addition, it should be understood that the present invention is not limited to the specific embodiments described. On the contrary, any combination of the features and elements described below may be considered to implement the present invention, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are intended for illustration only and should not be considered as elements or limitations of the claims unless explicitly stated in the claims.

[0044] In the following, terms such as "first", "second", etc. are used to describe the elements of the present application. These terms are only used to distinguish the various elements, and are not used to limit the nature, order or number of these elements. The terms "including" and "having" are used to express an open-ended inclusive meaning, and mean that there may be additional elements / components in addition to the listed elements / components.

[0045] Figure 1 The circuit connection diagram of the integrated photovoltaic energy storage assembly according to the present invention is schematically shown. The integrated photovoltaic energy storage assembly includes a photovoltaic cell assembly as a basic element, and the photovoltaic cell assembly in this application specifically refers to a single solar cell panel 1, which can have a lower open circuit voltage of less than 80V. In addition, the integrated photovoltaic energy storage assembly also includes an AC / DC multi-directional conversion device 2 and an energy storage battery 3. Figure 1 As shown, the AC / DC multidirectional conversion device 2 connects the solar panel 1, the energy storage battery 3 and the AC power grid 4 to each other, and is configured to be able to perform the desired power conversion between the three in pairs as needed. For example, the AC / DC multidirectional conversion device 2 performs DC step-up and step-down conversion between the solar panel 1 and the energy storage battery 3, or the AC / DC multidirectional conversion device 2 performs AC / DC conversion between each of the solar panel 1 and the energy storage battery 3 and the AC power grid 4. In other words, the AC / DC multidirectional conversion device 2 is a multi-purpose power conversion unit that integrates a variety of different power conversion functions. In the present application, the AC power grid 4 includes not only an ordinary large power grid, but also a microgrid or other power electrical equipment that can receive or provide power.

[0046] The integrated photovoltaic energy storage assembly according to the present invention is an integrated structure in which a solar cell panel 1, an AC / DC multidirectional conversion device 2 and an energy storage battery 3 are integrated in hardware. Figure 2-1 and Figure 2-2 A rear view and a cross-sectional view are respectively shown of a first exemplary configuration of such an integrated structure, wherein Figure 2-2 The cross-sectional view is along Figure 2-1 It is taken from the AA line in . Figure 2-1 and Figure 2-2 The illustrated integrated photovoltaic energy storage assembly includes a solar panel 1, an AC / DC multidirectional conversion device 2, and an energy storage battery 3 installed together. More specifically, the AC / DC multidirectional conversion device 2 and the energy storage battery 3 are both installed on the back of a single solar panel 1. As described above, the AC / DC multidirectional conversion device 2 is a multi-purpose power conversion unit, so it is advantageously packaged in a single housing. The energy storage battery 3 can be a battery module composed of a plurality of battery cells, and can be, for example, a blade battery, a soft pack battery, or a solid-state battery.

[0047] The solar cell panel 1 is provided with Figure 2-1 points out of the page in the rear view, or Figure 2-2 The AC / DC multi-directional conversion device 2 and the energy storage battery 3 are installed in place on the back of the solar panel 1. The extended height (referring to the maximum height that any part of them can reach in the direction toward the back side of the solar panel 1) does not exceed the back side end surface of the frame 11 (at the back side of the solar panel 1). Figure 2-1 1 is shown as a rectangular frame located at the outer periphery of the solar cell panel 1).

[0048] In addition to the solar cell panel 1, the AC / DC multidirectional conversion device 2 and the energy storage battery 3 are the entire photovoltaic energy storage component in the thickness direction ( Figure 2-1 in a direction perpendicular to the paper, or Figure 2-2 The components that occupy the most space in the left and right directions (in the left and right directions), and their extension height on the back of the solar panel 1 will not exceed the back side end surface of the frame 11 of the solar panel, so the thickness of the entire photovoltaic energy storage assembly is equal to the thickness of the original solar panel 1 (including its frame 11), thereby maintaining the regular shape of the single solar panel 1. In this way, it is particularly convenient for multiple integrated photovoltaic energy storage assemblies according to the present invention to be stacked on each other, thereby facilitating the storage, transportation and installation of photovoltaic energy storage assembly products in a space-saving and cost-saving manner. In the integrated photovoltaic energy storage assembly according to the present invention, as described in more detail below, in particular, the structure and / or arrangement of the AC / DC multi-directional conversion device 2 and the energy storage battery 3 can be designed so that even after the AC / DC multi-directional conversion device 2 and the energy storage battery 3 are integrated on the conventional solar panel 1, the thickness of the single solar panel 1 will not be increased and its shape will not be changed. Advantageously, the integrated photovoltaic energy storage assembly according to the present invention can be implemented without increasing the thickness of existing mainstream photovoltaic assemblies (the overall thickness of mainstream photovoltaic assemblies is not greater than 36 mm; the back gap height is not greater than 28 mm, and the back gap height refers to the distance between the back side of the solar cell panel in the photovoltaic assembly and the back side end face of its frame).

[0049] like Figure 2-1 and Figure 2-2 As shown, the AC / DC multi-directional conversion device 2 and the energy storage battery 3 can be installed on the back of the solar panel 1 through a bracket 12. The bracket 12 can be fixed on the frame 11 within the frame 11, and can be formed into various suitable configurations for facilitating the installation of the AC / DC multi-directional conversion device 2 and the energy storage battery 3, such as but not limited to the integrated grid-shaped bracket shown in the figure, which defines a plurality of grids, so that the AC / DC multi-directional conversion device 2 and the energy storage battery 3 can be respectively installed in different grids. Figure 2-1 and Figure 2-2 In the first embodiment shown, the AC / DC multidirectional conversion device 2 is installed in the central position of the bracket 12, and the multiple battery cells of the energy storage battery 3 (such as the blade batteries shown in the figure) are placed on both sides of the AC / DC multidirectional conversion device 2. Compared with the AC / DC multidirectional conversion device 2 and the energy storage battery 3, the bracket 12, which is much simpler in structure and function, also has a more compact size. Therefore, after being fixed in place on the frame 11, the extension height of the bracket 12 will not exceed the back side end surface of the frame 11. The bracket 12 can be fixed to the frame 11 by various appropriate methods, such as but not limited to screw fixing, riveting fixing or screw pressing block fixing.

[0050] In order to reduce the thickness, the energy storage battery 3 can be a battery module formed by multiple blade batteries, multiple soft-pack batteries or multiple solid-state batteries. In order to minimize the thickness of the energy storage battery 3 to avoid its extension height exceeding the back end surface of the frame 11 of the solar panel, the multiple battery cells (such as multiple blade batteries or multiple soft-pack batteries or multiple solid-state batteries) constituting the energy storage battery 3 can be arranged in a single-layer flat form. However, if the thickness requirements are met, at least a portion of the multiple battery cells can also be arranged in a stacked manner (for example, for blade batteries whose battery cell thickness is already small). The individual battery cells in the energy storage battery 3 can be divided into different modules and arranged flexibly according to the configuration of the bracket 12 and the spatial layout in the frame 11. The number and layout position of the modules and the number and arrangement of the battery cells in each module can be flexibly adjusted, so that energy storage batteries 3 of different capacities and photovoltaic energy storage component products of different specifications can be formed.

[0051] As an example, the energy storage battery 3 may also be equipped with a battery management system (BMS), which is used to monitor and manage the charging and discharging process of each battery cell in the energy storage battery, thereby ensuring the safe operation of the energy storage battery, preventing overcharging or overdischarging, and realizing the balance control inside the battery. The battery management system can communicate with the energy storage battery 3 and its battery cells via wired or wireless means. Figure 2-1 and Figure 2-2In the illustrated embodiment, the battery management system can be integrated in the AC / DC multi-directional conversion device 2 so as not to occupy additional space, and the extension height of the AC / DC multi-directional conversion device 2 including the battery management system on the back side of the solar panel 1 will not exceed the back side end surface of the frame 11.

[0052] Figure 3-1 and Figure 3-2 The rear views of the integrated photovoltaic energy storage assembly according to the second exemplary embodiment of the present invention are shown respectively. Figure 3-2 The cross-sectional view is along Figure 3-1 It is taken from the AA line in the figure. Figure 3-1 and Figure 3-2 In the second embodiment shown, the battery management system 31 can also be arranged separately from the AC / DC multi-directional conversion device 2. Figure 3-1 and Figure 3-2 As shown in FIG. 1 , the battery management system 31 is also mounted on the back of the solar panel 1 through the bracket 12. Figure 2-1 and Figure 2-2 Compared with the first embodiment shown, the structure of the integrated grid-shaped bracket 12 is slightly adjusted, and an assembly grid is also provided for the battery management system 31. Here, the independent battery management system 31 has a smaller size than the AC / DC multi-directional conversion device 2, and after being installed on the back of the solar panel 1 through the bracket 12, its extended height will not exceed the back side end surface of the frame 11.

[0053] Under the condition that the overall size requirements of the photovoltaic energy storage assembly of the present invention are met, it includes Figure 2-1 , Figure 2-2 and Figure 3-1 , Figure 3-2 Various configurations of the battery management system, including the embodiments shown, are feasible and will not affect the overall performance of the photovoltaic energy storage assembly.

[0054] After the installation of the various components of the above-mentioned integrated photovoltaic energy storage assembly, including the AC / DC multidirectional conversion module 2, the energy storage battery 3 and its battery management system, the bracket 12, and various connecting wires and fixing structures, the extension height of the back of the solar panel 1 will not exceed the back side end surface of the frame 11, so that the appearance of the entire photovoltaic energy storage assembly is the same as that of a single solar panel 1. Such an integrated photovoltaic energy storage assembly can also be conveniently equipped with a protective film or protective shell to protect various components from damage during transportation and installation, and can also be used for waterproofing and dustproofing to resist the influence of the external use environment.

[0055] The following describes in detail an AC / DC multidirectional conversion device in an integrated photovoltaic energy storage assembly according to an exemplary embodiment of the present invention, which is the core of the photovoltaic energy storage assembly. Figure 4The internal structure diagram of the AC / DC multi-directional conversion device is shown.

[0056] like Figure 4 As shown in , the AC / DC multi-directional conversion device includes three groups of connection terminals, multiple voltage converters, multiple switching elements and a control chip. The three groups of connection terminals are respectively a first group of connection terminals electrically connected to the positive and negative poles PV+ and PV- of the solar panel 1, a second group of connection terminals electrically connected to the positive and negative poles BAT+ and BAT- of the energy storage battery 3, and a third group of connection terminals electrically connected to the neutral and live wires L and N of the AC power grid.

[0057] The multiple voltage converters may include a DC buck-boost converter (i.e., a DC / DC module) and an AC / DC bidirectional converter (i.e., a bidirectional AC / DC module). The DC / DC module may be composed of one or more of a boost circuit Boost, a buck circuit Buck, and a boost-buck circuit Boost-Buck, and the bidirectional AC / DC module may include a rectifier circuit and an inverter circuit, and the rectifier circuit and the inverter circuit may be the same hardware circuit or different hardware circuits.

[0058] Each switch element plays a key role in connecting various modules inside the AC / DC multi-directional conversion device. Specifically, under the control of the control chip 7, depending on the different working modes of the integrated photovoltaic energy storage component, each switch element can electrically connect the corresponding voltage converter with another voltage converter or with the corresponding connection end, thereby establishing the required voltage conversion path between the corresponding two groups of connection ends. For example, when it is necessary to transmit the electric energy of the solar panel to the energy storage battery, the output side of the solar panel is connected to the DC / DC converter by controlling the corresponding switch element, and then the output of the DC / DC converter is connected to the input side of the energy storage battery through another switch element, thereby realizing the transmission of electric energy from the solar panel to the energy storage battery.

[0059] The control chip 7 is the "brain" of the entire conversion device. It can monitor the circuit state of the conversion device in real time, selectively control the on-off state of each switch element and the working state of each conversion module, so as to realize various voltage conversion functions of the AC-DC bidirectional conversion device. The control chip can realize the multidirectional voltage conversion function of the AC-DC bidirectional conversion device from AC to DC, from DC to AC, or from DC to DC by controlling the switch elements and different switch tube combinations in the AC-DC multidirectional conversion device. Furthermore, the AC-DC bidirectional conversion device can realize at least four working modes of the integrated photovoltaic energy storage component, including solar power supply mode, DC charging mode, AC charging mode and battery power supply mode.

[0060] Here, "solar power supply mode" refers to the use of solar panels to generate electricity for the AC grid or to supply power to the microgrid. In this mode, the DC power output by the solar panel needs to be converted into AC power by means of a DC / DC converter and a bidirectional AC / DC converter, and finally transmitted to the AC grid. "DC charging mode" refers to the use of solar panels to charge energy storage batteries. In this mode, the DC power output by the solar panel needs to be stepped up or stepped down by a DC / DC converter, and finally transmitted to the energy storage battery. "AC charging mode" refers to the use of power generation devices in the AC grid to charge energy storage batteries. In this mode, the AC power of the AC grid needs to be converted into DC power by means of a bidirectional AC / DC converter and a DC / DC converter, and then stepped up or stepped down, and finally transmitted to the energy storage battery. "Battery power supply" refers to the use of energy storage batteries to supply power to the AC grid (or microgrid). In this mode, the DC power output by the energy storage battery needs to be stepped up or stepped down by a DC / DC converter and a bidirectional AC / DC converter, and then converted into AC power, and finally transmitted to the AC grid.

[0061] Optionally, the control chip 7 can also monitor the output current and output voltage generated by the solar panel in real time, and calculate the MPPT to achieve maximum power point tracking, so that the solar panel 1 is in the highest working efficiency state when it is connected to the grid for power generation or charging the energy storage battery. Among them, the power supply (PS) circuit of the control chip 7 can automatically match the power supply output of the solar panel or the energy storage battery.

[0062] Figure 5-1 to Figure 5-4 Schematic diagrams showing different circuit states of the AC / DC multi-directional conversion device under different working modes of the integrated photovoltaic energy storage assembly according to the present invention are shown respectively. Figure 5-1 to Figure 5-4 To elaborate on the circuit state and working principle of the AC / DC multi-directional conversion device in different working modes.

[0063] Figure 5-1 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the solar power supply mode is shown. Figure 5-2 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the DC charging mode is shown. Figure 5-3 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the AC charging mode is shown. Figure 5-4 The circuit state diagram of the AC / DC multi-directional conversion device in the integrated photovoltaic energy storage assembly according to the present invention in the battery power supply mode is shown.

[0064] like Figure 5-1 to Figure 5-4As shown in , the AC / DC multi-directional conversion device has three sets of connection terminals, which are respectively connected to the positive and negative poles PV+ and PV- of the solar panel, the positive and negative poles BAT+ and BAT- of the energy storage battery, and the neutral and live wires L and N of the AC power grid (or microgrid).

[0065] The core part of the AC / DC multi-directional conversion device is composed of multiple voltage converters and multiple switch elements. Depending on the working mode to be achieved by the integrated photovoltaic energy storage component, by selectively connecting the corresponding switch elements and controlling the working state of each voltage converter with the help of the control chip 7, a corresponding voltage conversion path can be established between the corresponding two groups of connection terminals.

[0066] The AC / DC multi-directional conversion device has a first DC / DC converter 8, a second DC / DC converter 9 and a bidirectional AC / DC converter 10, as well as first, second and third switching elements S1, S2, S3, each switching element being assigned to a corresponding switching element in the AC / DC multi-directional conversion device, for example, the first switching element S1 is assigned to the first DC / DC converter 8, the second switching element S2 is assigned to the second DC / DC converter 9, and the third switching element S3 is assigned to the bidirectional AC / DC converter 10.

[0067] In this article, the expression "assigned to" describes the specific association configuration / assignment relationship between the switching element and the converter, that is, the switching element is assigned or designated to work with a specific converter. This "assignment" relationship indicates that although the specific position of the switching element can be flexibly set in the circuit, its main function is to serve the voltage converter to which it is "assigned" and to achieve different working modes of the photovoltaic energy storage component by controlling the current flow path associated with the converter. Therefore, the expression "assigned to" in this article is not intended to limit the physical position of the switching element, but to emphasize its startup control relationship with a specific voltage converter in the system control logic.

[0068] exist Figure 5-1 to Figure 5-4In the circuit diagram shown, an exemplary connection relationship between each switch element and each converter is shown. Among them, the input side of the first DC / DC converter 8 is electrically connected to the positive and negative poles PV+ and PV- of the solar panel, and the input side of the second DC / DC converter 9 is electrically connected to the positive and negative poles BAT+ and BAT- of the energy storage battery. The first switch element S1 connects the output side of the first DC / DC converter 8 to the first end of the third switch element S3, and the second switch element S2 connects the output side of the second DC / DC converter 9 to the first end of the third switch element S3. The DC side of the bidirectional AC / DC converter 10 is connected to the second end of the third switch element S3, and its AC side is connected to the AC power grid (or microgrid). The on-off state of these switch elements, the working state (boost or buck) of the DC / DC converter, and the working state (inversion or rectification) of the AC / DC converter are controlled by the control chip as a whole, so as to finally realize different working modes of the photovoltaic energy storage component.

[0069] exist Figure 5-1 In the solar power supply mode, the photovoltaic energy storage component works in the solar power supply mode, and the control chip 7 turns on the first and third switch elements S1 and S3, so that the first direct current generated by the solar panel is regulated in voltage (boosted or bucked) by the first DC / DC converter 8, and then inverted and converted into the first alternating current by the bidirectional AC / DC converter 10, and finally supplies power to the AC power grid. In this solar power supply mode, the switch elements S1 and S3 are closed, S2 is disconnected, and the bidirectional AC / DC converter 10 is in the inverter state, and the electric energy of the solar panel can be used to realize grid-connected power generation or power supply for the microgrid.

[0070] exist Figure 5-2 In the embodiment, the photovoltaic energy storage component works in the DC charging mode, and the control chip 7 turns on the first and second switch elements S1 and S2, so that the first DC power generated by the solar panel is converted into an intermediate DC power through the first DC / DC converter 8, and then converted into a second DC power suitable for charging the energy storage battery through the second DC / DC converter 9. At this time, the first and second DC / DC converters are in a DC boost or buck state, depending on the output voltage of the solar panel and the charging requirement voltage of the energy storage battery. In this DC charging mode, the switch elements S1 and S2 are closed, S3 is disconnected, and the bidirectional AC / DC converter 10 does not work, which can realize the efficient charging of the energy storage battery using the electric energy of the solar panel.

[0071] exist Figure 5-3In the embodiment, the photovoltaic energy storage component works in the AC charging mode, the control chip 7 turns on the second and third switch elements S2 and S3, and makes the bidirectional AC / DC converter 10 work in the rectification state. At this time, the first AC power from the AC power grid is rectified by the bidirectional AC / DC converter 10 and converted into DC power, and the DC power is then converted into the second DC power suitable for charging the energy storage battery after voltage regulation by the second DC / DC converter 9. In this AC charging mode, the bidirectional AC / DC converter 10 is in the rectification state, S2 and S3 are closed, and S1 is disconnected, so that the AC power of the AC power grid can be used to charge the energy storage battery.

[0072] exist Figure 5-4 In the embodiment, the photovoltaic energy storage component works in the battery power supply mode, the control chip 7 turns on the second and third switch elements S2 and S3, and makes the bidirectional AC / DC converter 10 work in the inverter state. At this time, the DC power generated by the energy storage battery is voltage regulated (boosted or bucked) by the second DC / DC converter 9, and then inverted and converted into the first AC power by the bidirectional AC / DC converter 10, and finally supplies power to the AC power grid. In this battery power supply mode, the bidirectional AC / DC converter 10 is in the inverter state, S2 and S3 are closed, and S1 is disconnected, so that the DC power of the energy storage battery can be used to supply power to the AC power grid.

[0073] By Figure 5-1 to Figure 5-4 The integrated photovoltaic energy storage assembly of the present invention can flexibly switch between the four working modes shown in the figure, and can achieve efficient utilization of solar panels, flexible charging and discharging of energy storage batteries, and stable interaction with the AC power grid, and can adapt to different operating scenarios.

[0074] Although Figure 5-1 to Figure 5-4 It is shown that the switch elements S1-S3 are respectively arranged between each voltage converter, but this arrangement is only schematic and is not the only feasible implementation method. In fact, the positions of these switch elements can be flexibly adjusted. For example, they can also be arranged on the side of the connection end of the AC / DC multi-directional conversion device to directly control the connection and disconnection of the connection end. This arrangement can also achieve effective control of the voltage conversion path, thereby realizing the flexible switching of the current flow path of the photovoltaic energy storage component under different working modes. Therefore, even if the setting position of the switch elements changes, as long as they can selectively connect or disconnect the relevant conversion path according to the instructions of the control chip 7, the expected working mode of the photovoltaic energy storage component can be achieved.

[0075] It is important that no matter where the switch element is set, it can be implemented by using a variety of types of switch devices, including but not limited to metal oxide semiconductor field effect transistors (referred to as "MOSFET"), triodes, relays or insulated gate bipolar transistors (referred to as "IGBT"), etc. These switch devices can be selected according to the specific needs of the AC / DC multi-directional conversion device due to their different characteristics and applicable scenarios to ensure efficient, safe and reliable operation of the converter. In addition, the switch elements S1-S3 can be either independently set switches or switch tubes shared with the DC / DC converter or the bidirectional AC / DC converter. The switch tube is selected from a group including diodes, triodes, thyristors, MOS tubes and IGBTs.

[0076] In the AC / DC multi-directional conversion device, the first and second DC / DC converters can adopt a highly flexible circuit design to adapt to different voltage conversion requirements. The first and second DC / DC converters are each implemented as any one of a Boost circuit, a Buck circuit, and a Boost-Buck circuit.

[0077] Figure 6 FIG. 1 is a schematic diagram showing the output voltage waveform of the solar panel in the integrated photovoltaic energy storage assembly according to the present invention. Figure 6 As shown in , the output voltage of the solar panel is not a stable DC voltage, but is doped with high-frequency or low-frequency noise signals. Therefore, before performing a step-up and step-down operation on the output voltage of the solar panel, it is necessary to filter it with the help of a filtering module, which can be integrated in the first DC / DC converter, for example.

[0078] Figure 7-1 The internal circuit diagram of the first or second DC / DC converter implemented as a Boost boost circuit is shown. The Boost boost circuit is suitable for situations where the output voltage of the solar panel is lower than the charging voltage of the energy storage battery. First, in order to filter out the noise signal in the output voltage of the solar panel, the Boost boost circuit includes a first capacitor module on the input side. The capacitor module is composed of electrolytic capacitors C1-C4 and chip capacitors C6-C9 connected in parallel. Among them, the electrolytic capacitors C1-C4 have a diameter less than 17mm, the number is 4-8, the capacitance is 800μF-3000μF, the number of chip capacitors C6-C9 is 4-14, and the capacitance is 1-10μF.

[0079] The electrolytic capacitors C1-C4 and the chip capacitors C6-C9 can better suppress the ripple and high-order harmonic interference in the input signal of the boost circuit. Among them, the electrolytic capacitor can effectively suppress the low-frequency filtering part, and the chip capacitor can make up for the lack of electrolytic capacitor filtering on the high-frequency part, so that the diameter of the electrolytic capacitor is reduced and the life is extended. In short, the design of the capacitor module ensures its compact layout in a limited space and ensures the stability of the output voltage of the DC / DC converter.

[0080] Downstream of the capacitor module, a conventional Boost circuit is provided, which is composed of an energy storage inductor L, two switch tubes Q1 and Q2, and an energy storage capacitor C5. The control terminals of the switch tubes Q1 and Q2 are P1 and P2, respectively. The control terminals P1 and P2 are respectively connected to the control chip 7, so that the switch tubes Q1 and Q2 are alternately turned on / off under the control of the control chip 7, thereby realizing the boost function of the circuit. Here, the switch tube Q2 can be a MOSFET or a diode. If it is a MOSFET, it can reuse the same switch as the switch element S1 or S2 in the AC / DC multi-directional conversion device.

[0081] Figure 7-2 The internal circuit diagram of the first or second DC / DC converter implemented as a Buck buck circuit is shown. The Buck buck circuit is suitable for the situation where the output voltage of the solar panel is higher than the charging voltage of the energy storage battery. Similarly, in order to filter out the noise signal in the output voltage of the solar panel, the Buck buck circuit includes a capacitor module on the input side. The capacitor module is composed of electrolytic capacitors C1-C4 and chip capacitors C6-C9 connected in parallel. Among them, the diameter of the electrolytic capacitors C1-C4 is less than 17mm, the number is 4-8, the capacitance is 800μF-3000μF, the number of chip capacitors C6-C9 is 4-14, and the capacitance is 1-10μF.

[0082] The combined filtering of electrolytic capacitors C1-C4 and chip capacitors C6-C9 can better suppress the ripple and high-order harmonic interference in the input signal of the buck circuit. Among them, the electrolytic capacitor can effectively suppress the low-frequency filtering part, and the chip capacitor can make up for the lack of electrolytic capacitor filtering on the high-frequency part, so that the diameter of the electrolytic capacitor is reduced and the life is extended.

[0083] Downstream of the capacitor module, a conventional Buck circuit is set, which is composed of an energy storage inductor L, two switch tubes Q1 and Q2, and an energy storage capacitor C5. The control terminals of the switch tubes Q1 and Q2 are P1 and P2 respectively. The control terminals P1 and P2 are respectively connected to the control chip, so that the switch tubes Q1 and Q2 are alternately turned on / off under the control of the control chip, thereby realizing the circuit's voltage reduction function. Here, the switch tube Q2 can be a MOSFET or a diode.

[0084] Figure 7-3The internal circuit diagram of the first or second DC / DC converter implemented as a Boost-Buck buck-boost circuit is shown. The Boost-Buck buck-boost circuit is suitable for situations where the output voltage of the solar panel is sometimes higher than the charging voltage of the energy storage battery and sometimes lower than the charging voltage of the energy storage battery. In order to filter out the noise signal in the output voltage of the solar panel, the Boost-Buck buck-boost circuit includes a capacitor module on the input side. The capacitor module is composed of electrolytic capacitors C1-C4 and chip capacitors C6-C9 connected in parallel. Among them, the diameter of the electrolytic capacitors C1-C4 is less than 17mm, the number is 4-8, the capacitance is 800μF-3000μF, the number of chip capacitors C6-C9 is 4-14, and the capacitance is 1-10μF.

[0085] The combined filtering of electrolytic capacitors C1-C4 and chip capacitors C6-C9 can better suppress the ripple and high-order harmonic interference in the input signal of the buck-boost circuit. Among them, the electrolytic capacitor can effectively suppress the low-frequency filtering part, and the chip capacitor can make up for the lack of electrolytic capacitor filtering on the high-frequency part, so that the diameter of the electrolytic capacitor is reduced and the service life is extended.

[0086] Downstream of the capacitor module, a conventional Boost-Buck circuit is provided, which is composed of an energy storage inductor L, two switch tubes Q1 and Q2, and an energy storage capacitor C5. The switch tube Q1 is provided at the input side of the Boost-Buck circuit, the switch tube Q2 is provided at the output side of the Boost-Buck circuit, and the energy storage inductor L is provided between the switch tubes Q1 and Q2. The switch tube Q2 can be a MOSFET or a diode. If it is a MOSFET, the same switch can be reused with the switch element S1 or S2 in the AC / DC multi-directional conversion device.

[0087] The control terminals of the switch tubes Q1 and Q2 are P1 and P2 respectively, and the control terminals P1 and P2 are connected to the control chip 7 respectively. According to the output voltage of the solar panel and the charging voltage of the energy storage battery, the control chip can dynamically adjust the duty ratio of Q1 and Q2, so as to realize the free switching of the Boost-Buck circuit between the boost mode and the buck mode. For example, when the output voltage of the solar panel is lower than the charging voltage of the energy storage battery, the Boost-Buck circuit works in the boost mode; and when the output voltage of the solar panel is higher than the charging voltage of the energy storage battery, the Boost-Buck circuit works in the buck mode.

[0088] In the AC / DC multi-directional conversion device, depending on the specific application scenario of the integrated photovoltaic energy storage component (for example, the working voltage of the connected AC power grid), the bidirectional AC / DC converter can adopt two forms: an isolated transformer structure and a non-isolated transformer structure.

[0089] Figure 8-1 The schematic diagram of the internal circuit structure of a bidirectional AC / DC converter using an isolated transformer structure is shown. Figure 8-1 In the circuit design of the bidirectional AC / DC converter, an isolation transformer is used to meet the requirements for electrical isolation in specific occasions (such as the United States). The bidirectional AC / DC converter is based on a variation of the dual active bridge circuit (DAB) to achieve bidirectional and efficient conversion between DC and AC.

[0090] The core structure of the modified dual active bridge circuit includes an isolation transformer T, a first switch circuit, a second switch circuit and an inductor Ls. The input side of the first switch circuit is connected to the DC side of the bidirectional AC / DC converter, the inductor Ls is arranged between the secondary side of the isolation transformer T and the input side of the second switch circuit, and the output side of the second switch circuit is electrically connected to the AC side of the bidirectional AC / DC converter. Here, the secondary leakage inductance of the isolation transformer T can also be used to replace the inductor Ls, thereby omitting the additional secondary inductor.

[0091] As an optional example, one or more capacitors may be separately provided on the primary side of the isolation transformer T, especially between the output side of the first switch circuit and the primary side of the isolation transformer T, to filter out the DC component in the electrical signal received by the primary side of the isolation transformer. As another optional example, another resonant circuit composed of a primary side inductor and a primary side capacitor may be provided on the primary side of the isolation transformer T.

[0092] The first and second switch circuits both adopt a full-bridge topology structure, wherein the four bridge arms in the first switch circuit are respectively formed by switch tubes Q1 - Q4 , and the corresponding control terminals P1 - P4 of the four switch tubes Q1 - Q4 are respectively connected to the control chip 7 .

[0093] In the second switch circuit, the first upper bridge arm and the first lower bridge arm forming the first half bridge are composed of two switch tubes (MOSFET Q5, Q6 and Q7, Q8) connected in series in a back-to-back manner, and the second upper bridge arm and the second lower bridge arm forming the second half bridge are composed of a single capacitor (C1 and C2). That is to say, on the AC side of the bidirectional AC / DC converter, one terminal of the secondary side of the isolation transformer T is connected in series with two groups of parallel circuits, one group is formed by the series connection of switch tubes Q5, Q6 and C1, and the other group is formed by the series connection of switch tubes Q7, Q8 and C2. The source electrodes of the switch tubes Q5 and Q6 are connected, and the source electrodes of the switch tubes Q7 and Q8 are connected, and finally return to the other terminal of the secondary side of the isolation transformer T. The control terminals P1-P8 of the switch tubes Q1-Q8 are respectively turned on in sequence by the control chip 7 according to the requirements of bidirectional rectification or inversion mode, AC power frequency (phase) synchronization, etc.

[0094] On the secondary side of the isolation transformer T, based on Figure 8-1The topological structure of the second switch circuit and the inductor Ls (or the leakage inductance of the transformer) shown in the figure, the control chip 7 can selectively control the on-off state of the four switch tubes Q5, Q6, Q7, and Q8, thereby forming a first resonant circuit through the inductor Ls and the capacitor C1, or forming a second resonant circuit through the inductor Ls and the capacitor C2, and finally realizing the voltage / current waveform required on the secondary side of the transformer.

[0095] Specifically, Figure 8-1 As shown in , when the bidirectional AC / DC converter works in the rectification mode, for example, when the AC power of the AC power grid needs to be used to charge the energy storage battery, the AC side of the bidirectional AC / DC converter receives the AC power signal LN from the AC power grid. In the positive half cycle of the AC power signal LN, the control chip 7 is used to keep the switch tubes Q6 and Q8 in the second switch circuit normally on, so that the switch tubes Q5 and Q7 perform high-frequency on-off operations alternately (that is, when Q5 is on, Q7 is off, and vice versa). On the contrary, in the negative half cycle of LN, the control chip 7 is used to keep the switch tubes Q5 and Q7 normally on, so that the switch tubes Q6 and Q8 perform high-frequency on-off operations alternately. At the same time, on the DC side of the bidirectional AC / DC converter, the switch tubes Q1, Q4 and the switch tubes Q2, Q3 in the first switch circuit are alternately turned on to cooperate with the switch tube action on the AC side (that is, when the switch tubes Q1, Q4 are synchronously turned on, the switch tubes Q2, Q3 are synchronously turned off, and vice versa), thereby realizing power transmission from the second switch circuit on the AC side to the first switch circuit on the DC side.

[0096] When the bidirectional AC / DC converter works in the inverter mode, for example, when it is necessary to use solar panels or energy storage batteries to supply power to the AC grid, on the DC side, the switch tubes Q1, Q4 and the switch tubes Q2, Q3 are alternately operated to perform high-frequency on-off operations, thereby converting the DC power received on the DC side into high-frequency AC power. At the same time, on the AC side, the control chip 7 controls the switch tubes Q5~Q8 to work synchronously with the high-frequency signal on the DC side. For example, in the positive half cycle, Q5 and Q7 are kept on, and Q6 and Q8 are alternately turned on and off; in the negative half cycle, Q6 and Q8 are kept on, and Q5 and Q7 are alternately turned on and off, thereby realizing the transmission of power from the first switch circuit on the DC side to the second switch circuit on the AC side.

[0097] In the above conversion process, the on-off frequency of the DC side switch tube is kept at the same frequency as the switch tube that performs high-frequency on-off operations on the AC side, and a phase shift angle is formed between the switch tube signal that performs high-frequency on-off operations on the AC side and the switch tube signal on the DC side. By adjusting the size of the phase shift angle, for example, making the AC side switch tube signal lead or lag behind the DC side switch tube signal, the current direction on the inductor Ls is adjusted, so that the entire converter operates in rectification or inversion mode.

[0098] In order to meet the overall size requirements of the photovoltaic energy storage component, the design parameters of the isolation transformer are optimized. According to E=4.44fNQm, where E is the electromotive force, f is the frequency, N is the number of turns, and Qm is the magnetic flux, when the thickness of the isolation transformer becomes thinner, N decreases and Qm also decreases. By increasing the frequency f, the impact caused by the decrease in N and Qm can be compensated.

[0099] After testing, when the operating frequency is in the range of 8KHz to 300KHz, the number of turns of the primary coil of the isolation transformer is set to 3 to 6 turns, the number of turns of the secondary coil is set to 9 to 18 turns, and the turns ratio is set to between 2 and 4. The primary inductance is between 50μH and 1.5mH, and the secondary leakage inductance is between 5μH and 200μH. When the thickness of the transformer becomes thinner, the number of turns and the magnetic flux are reduced, the impact of these changes can be compensated by increasing the frequency f, while keeping the height of the isolation transformer less than 17mm.

[0100] In addition, the bidirectional AC / DC converter also includes a second capacitor module, which is arranged between the second switch circuit and the AC power grid. The capacitor module is composed of 1 to 3 safety capacitors Cx2 with a height less than 17mm, which are used for AC side filtering of the bidirectional AC / DC converter. Since high-frequency operation reduces the requirements for the height of safety capacitors, their height is also less than 17mm. Through this isolated transformer structure design of the bidirectional AC / DC converter, not only the efficient conversion between DC and AC is achieved, but also the compact space and high performance requirements of the photovoltaic energy storage components are met, while the safety requirements of electrical isolation are met.

[0101] Figure 8-2 The schematic diagram of the internal circuit structure of a bidirectional AC / DC converter using a non-isolated transformer structure is shown. Figure 8-2 In the circuit design of the bidirectional AC / DC converter, a non-isolated transformer structure is adopted, which is suitable for scenarios where electrical isolation is not required.

[0102] Among them, the bidirectional AC / DC converter includes a bidirectional full-bridge converter composed of four switching tubes Q1-Q4 and an LC resonator. The DC side of the bidirectional full-bridge converter is electrically connected to the second end of the third switching element S3, and the LC resonator is arranged between the AC side of the bidirectional full-bridge converter and the AC power grid.

[0103] The switch tubes Q1-Q4 can be MOSFET, thyristor, etc., and are controlled by the control chip 7 to work in the rectification or inversion state. Similarly, by increasing the switching frequency of the switch tube, the quality of the output side waveform can be improved, and the height requirement of the safety capacitor Cx2 (used for AC measurement filtering) can be reduced to less than 17mm. The number of the safety capacitors used is 1-3.

[0104] As described above, the above-mentioned designs of the internal circuit structure of the AC / DC multi-directional conversion device are conducive to achieving the compact size of the AC / DC multi-directional conversion device, and especially reducing its size in the thickness direction of the integrated photovoltaic energy storage component, thereby ensuring that the extension height of the AC / DC multi-directional conversion device on the back of the solar cell panel does not exceed the back end surface of its frame, thereby enabling the entire photovoltaic energy storage component to be realized without increasing the thickness of the existing mainstream photovoltaic components (the overall thickness of the mainstream photovoltaic components is not more than 36 mm, and the back gap height is not more than 28 mm).

[0105] For those skilled in the art, various modifications and variations may be made to the embodiments disclosed above without departing from the scope or spirit of the present invention. Other embodiments of the present invention will be apparent to those skilled in the art from the practice of the present invention disclosed in this specification. This specification and the examples disclosed therein should be considered to be illustrative only, and the true scope of the present invention is specified by the appended claims and their equivalents.

Claims

1. An integrated photovoltaic energy storage assembly, comprising a solar panel (1), an AC / DC multidirectional conversion device (2), and an energy storage battery (3), The solar panel is provided with a frame (11) extending toward the back side thereof, the AC / DC multidirectional conversion device and the energy storage battery are mounted on the back side of the solar panel and the extension height does not exceed the back side end face of the frame, The AC / DC multidirectional conversion device (2) comprises three groups of connection terminals, a plurality of voltage converters, a plurality of switch elements and a control chip (7), wherein the three groups of connection terminals are electrically connected to a solar cell panel, an energy storage battery and an AC power grid respectively, and each switch element is configured to electrically connect a corresponding one of the plurality of voltage converters to another converter of the plurality of voltage converters, or to electrically connect a corresponding one of the three groups of connection terminals, and the control chip (7) is configured to selectively connect at least one of the plurality of switch elements in different working modes of the integrated photovoltaic energy storage assembly, so as to establish a voltage conversion path between corresponding two of the three groups of connection terminals with the aid of at least one of the plurality of voltage converters.

2. The integrated photovoltaic energy storage assembly according to claim 1, characterized in that: The AC / DC multidirectional conversion device (2) and the energy storage battery (3) are mounted on the back side of the solar cell panel (1) via an integrated lattice-shaped bracket (12) fixed to the frame within the frame (11).

3. The integrated photovoltaic energy storage assembly according to claim 1, characterized in that: The energy storage battery (3) comprises a battery module composed of a plurality of blade batteries, a plurality of soft-pack batteries or a plurality of solid-state batteries.

4. The integrated photovoltaic energy storage assembly according to claim 1, characterized in that: The integrated photovoltaic energy storage assembly also includes a battery management system (31) which is integrated in the AC / DC multi-directional conversion device (2) or is separately arranged from the AC / DC multi-directional conversion device.

5. The integrated photovoltaic energy storage assembly according to any one of claims 1 to 4, characterized in that: The multiple voltage converters include a first DC / DC converter (8), a second DC / DC converter (9) and a bidirectional AC / DC converter (10), wherein the input side of the first DC / DC converter (8) is electrically connected to a solar panel, the input side of the second DC / DC converter (9) is electrically connected to an energy storage battery, and the AC side of the bidirectional AC / DC converter (10) is electrically connected to an AC power grid; the multiple switch elements include first to third switch elements (S1, S2, S3), wherein the first switch element (S1) is assigned to the first DC / DC converter (8), the second switch element (S2) is assigned to the second DC / DC converter (9), and the third switch element (S3) is assigned to the bidirectional AC / DC converter (10). The control chip (7) is further configured to selectively switch on corresponding two switch elements among the first to third switch elements, so as to realize different working modes of the integrated photovoltaic energy storage component with the help of corresponding two converters among the first DC / DC converter (8), the second DC / DC converter (9) and the bidirectional AC / DC converter (10).

6. The integrated photovoltaic energy storage assembly according to claim 5, characterized in that: The working modes of the integrated photovoltaic energy storage assembly include a solar power supply mode, a direct current charging mode, an alternating current charging mode and a battery power supply mode, wherein the control chip (7) is further configured as follows: In a solar power supply mode, the first and third switch elements (S1, S3) are turned on and the bidirectional AC / DC converter (10) is operated in an inverter state, so as to convert the first direct current from the solar panel into the first alternating current for supplying power to the alternating current grid by means of the first DC / DC converter (8) and the bidirectional AC / DC converter (10); In a DC charging mode, the first and second switch elements (S1, S2) are turned on to convert the first DC power from the solar panel into the second DC power for charging the energy storage battery by means of the first DC / DC converter (8) and the second DC / DC converter (9); In an AC charging mode, the second and third switch elements (S2, S3) are turned on and the bidirectional AC / DC converter (10) is operated in a rectifying state, so as to convert a first AC power from an AC power grid into a second DC power for charging an energy storage battery by means of the bidirectional AC / DC converter (10) and the second DC / DC converter (9); and In the battery power supply mode, the second and third switch elements (S2, S3) are turned on and the bidirectional AC / DC converter (10) is operated in an inverter state, so as to convert the second direct current from the energy storage battery into the first alternating current for supplying power to the alternating current grid with the help of the second DC / DC converter (9) and the bidirectional AC / DC converter (10).

7. The integrated photovoltaic energy storage assembly according to claim 5, characterized in that: The first and second DC / DC converters are each implemented as any one of a Boost circuit, a Buck circuit, and a Boost-Buck circuit.

8. The integrated photovoltaic energy storage assembly according to claim 7, characterized in that: The Boost-Buck step-up and step-down circuit comprises a first switch tube (Q1) arranged at the input side of a corresponding DC / DC converter, a second switch tube (Q2) arranged at the output side of the corresponding DC / DC converter, and an energy storage inductor (L) arranged between the first switch tube (Q1) and the second switch tube (Q2), wherein the control chip (7) is configured to control the duty cycle of the first and second switch tubes based on the output voltage of the solar panel and the charging voltage of the energy storage battery, so that the corresponding DC / DC converter operates in a step-up mode or a step-down mode.

9. The integrated photovoltaic energy storage assembly according to claim 5, characterized in that: The first and second DC / DC converters each include a first capacitor module, wherein the first capacitor module is composed of at least one electrolytic capacitor (C1-C4) and at least one chip capacitor (C6-C9).

10. The integrated photovoltaic energy storage assembly according to claim 9, characterized in that: The capacity of each electrolytic capacitor is 800μF-3000μF, the capacity of each chip capacitor is 1-10μF, and the diameter of each electrolytic capacitor is less than 17mm.

11. The integrated photovoltaic energy storage assembly according to claim 5, characterized in that: The bidirectional AC / DC converter includes an inductor, an isolation transformer, a first switch circuit and a second switch circuit, wherein the input side of the first switch circuit is electrically connected to the DC side of the bidirectional AC / DC converter, the inductor is arranged between the secondary side of the isolation transformer and the input side of the second switch circuit, and the output side of the second switch circuit is electrically connected to the AC side of the bidirectional AC / DC converter, wherein the first and second switch circuits respectively adopt a full-bridge topology structure, the four bridge arms of the first switch circuit are respectively composed of a single switch tube, the first upper bridge arm and the first lower bridge arm of the second switch circuit are respectively composed of two switch tubes connected in series in a back-to-back manner, and the second upper bridge arm and the second lower bridge arm of the second switch circuit are respectively composed of a single capacitor.

12. The integrated photovoltaic energy storage assembly according to claim 11, characterized in that: When the isolation transformer is in the frequency range of 8KHz to 300KHz, the number of turns of the primary coil of the isolation transformer is set to 3 to 6 turns, the number of turns of the secondary coil is set to 9 to 18 turns, the turns ratio is set to between 2 and 4, the primary inductance is between 50μH and 1.5mH, the secondary leakage inductance is between 5μH and 200μH, and the height of the isolation transformer is set to less than 17mm.

13. The integrated photovoltaic energy storage assembly according to claim 11 or 12, characterized in that: The bidirectional AC / DC converter further includes a second capacitor module disposed between the second switch circuit and the AC power grid, wherein the second capacitor module is composed of 1 to 3 safety capacitors (Cx2) with a height less than 17 mm.

14. The integrated photovoltaic energy storage assembly according to claim 5, characterized in that: The bidirectional AC / DC converter includes a bidirectional full-bridge converter composed of four switching tubes and an LC resonator. The DC side of the bidirectional full-bridge converter is electrically connected to the second end of the third switching element (S3), and the LC resonator is arranged between the AC side of the bidirectional full-bridge converter and the AC power grid.

15. The integrated photovoltaic energy storage assembly according to claim 14, characterized in that: The bidirectional AC / DC converter further includes a third capacitor module disposed between the LC resonator and the AC power grid, wherein the third capacitor module is composed of 1 to 3 safety capacitors (Cx2) with a height less than 17 mm.

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