Bidirectional photovoltaic energy storage micro inverter and photovoltaic energy storage system

Abstract

The utility model discloses a bidirectional photovoltaic energy storage micro inverter and a photovoltaic energy storage system. The system comprises at least one group of photovoltaic panels, a photovoltaic energy storage micro inverter, a direct current battery module and an alternating current load and / or an alternating current power grid, the photovoltaic energy storage micro inverter comprises at least one direct current boosting module, a direct current bus, a bidirectional isolation direct current boosting module, a bidirectional direct current / alternating current conversion module, a bidirectional non-isolation direct current conversion module and a control module. The photovoltaic energy storage system is simple in circuit structure, the calculated amount of the control module is small, the requirement for the performance of a processor of the control module is low, and the production cost is reduced. In addition, by adding the photovoltaic energy storage micro inverter, zero-voltage pipe section and zero-current opening can be realized under different conditions, and the suitability of the photovoltaic energy storage system is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of inverters, and in particular to a bidirectional photovoltaic energy storage micro inverter and a photovoltaic energy storage system. Background Art

[0002] Existing photovoltaic grid-connected inverters include: one is a centralized type, which aggregates the DC power generated by the photovoltaic panels and then inverts it into the AC power grid. It has the advantages of large output power, high power quality and low cost. The disadvantage is that it cannot perform MPPT (maximum power point tracking) or shut down each photovoltaic panel individually, the power generation efficiency is low, the high voltage on the DC side leads to poor safety, and the inability to shut down independently leads to low reliability. The other is a string type, which connects multiple photovoltaic panels in series to form a string, and then inverts it into the AC power grid. It has the advantages of grouped MPPT, flexible component configuration, high power generation and low cost, but it cannot perform MPPT or shut down each photovoltaic panel individually, there is also high voltage on the DC side, and the power generation quality is slightly poor and the cost is high.

[0003] A micro inverter is an inverter that is directly connected to one or more photovoltaic panels. Typically, a micro inverter is connected to no more than 8 photovoltaic panels, and the output power is less than 3000W. The micro inverter is directly connected to each photovoltaic panel independently, rather than connecting multiple photovoltaic panels in series and parallel and then connecting them to the inverter as in a centralized or string inverter system. Therefore, the micro inverter has the following advantages: (1) Each photovoltaic panel is directly connected to the inverter, with a maximum voltage of about 60V, which is safer; (2) Maximum power point tracking can be performed for each photovoltaic panel individually, which is more efficient; (3) A faulty photovoltaic panel can be shut down individually without affecting the operation of other connected photovoltaic panels, which is more reliable. The typical circuit topology of a micro inverter is interleaved flyback plus rectifier inversion, which can only operate in one direction and not in the reverse direction.

[0004] Photovoltaic power generation is affected by external conditions such as light and temperature, and the output voltage and output power fluctuate greatly. In practical applications, energy storage devices are required to form a photovoltaic power generation-energy storage system. Existing photovoltaic power generation-energy storage systems usually use a photovoltaic inverter plus an energy storage converter, which is costly, has low conversion efficiency, and is complex to install.

[0005] Therefore, a photovoltaic energy storage integrated inverter is proposed. On the basis of the photovoltaic grid-connected inverter, the energy storage battery is connected to the power grid system to perform AC / DC bidirectional conversion and charge and discharge of the energy storage battery, which plays a role in smoothing the output power curve, reducing the pressure of power grid dispatching, and saving electricity costs. It has the advantages of high conversion efficiency, compact structure, easy installation, and low cost. However, the energy storage inverter needs to realize bidirectional current conversion, which is more technically difficult and requires higher safety.

[0006] In summary, the shortcomings of existing photovoltaic energy storage inverter technology are:

[0007] (1) The circuit structure is complex and mutually coupled, the control algorithm is complex and the calculation is large, which places high demands on the processor performance of the control module.

[0008] (2) Since the input voltage range of photovoltaic panels is very wide (typically 20 to 60 V), it is difficult to achieve high conversion efficiency over a wide voltage range.

[0009] (3) The working mode of photovoltaic energy storage inverter is complex, and the working conditions of full-bridge inverter in different modes vary greatly. In order to take into account different needs, it is difficult to achieve zero voltage shutdown (ZVS) and zero current start (ZCS) under all conditions when designing and calculating the bidirectional power conversion circuit.

[0010] (4) A string architecture is usually used, which cannot perform MPPT tracking or shutdown on each PV panel individually, resulting in high voltage on the DC side. Utility Model Content

[0011] In order to solve at least one of the technical problems in the prior art, on the one hand, an embodiment of the utility model provides a bidirectional photovoltaic energy storage micro-inverter, which includes at least one DC boost module, a DC bus, a bidirectional isolated DC boost module, a bidirectional DC / AC conversion module, a bidirectional non-isolated DC conversion module and a control module; the input end of the at least one DC boost module is connected to the photovoltaic panel correspondingly, and the output end of the at least one DC boost module is connected to the DC bus, which is used to convert the changing output voltage of the photovoltaic panel into a stable DC bus voltage; the DC bus is bidirectionally connected to the low-voltage side of the bidirectional isolated DC boost module, and the high-voltage side of the bidirectional isolated DC boost module is connected to the DC side of the bidirectional DC / AC conversion module. The bidirectional isolated DC boost module is used to boost the DC bus voltage; the AC side of the bidirectional DC / AC conversion module is connected to the AC load or AC power grid, and is used to convert the boosted DC bus voltage into an AC voltage and output it to the AC load or AC power grid; the DC bus is bidirectionally connected to the high-voltage side of the bidirectional non-isolated DC conversion module, the low-voltage side of the bidirectional non-isolated DC conversion module is bidirectionally connected to the DC battery module, and the bidirectional non-isolated DC conversion module is used to enable energy transmission between the DC battery module and the DC bus; the control module is respectively connected to the at least one DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module and the bidirectional non-isolated DC conversion module, and is used to control the working mode of each module.

[0012] Furthermore, the bidirectional isolated DC boost module is a DC boost circuit with an isolation transformer, adopts a bidirectional full-bridge circuit topology, and its output voltage is higher than the input voltage.

[0013] Furthermore, the bidirectional DC / AC conversion module adopts a two-way staggered totem pole bridgeless PFC topology circuit and has two working modes: rectification mode and inverter mode.

[0014] Furthermore, the bidirectional non-isolated DC conversion module adopts a bidirectional phase-shifted full-bridge circuit topology, and adopts a buck mode when working in the forward direction to charge the DC battery module from the DC bus; and adopts a boost mode when working in the reverse direction to discharge from the DC battery module to the DC bus.

[0015] Furthermore, the circuits of the DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module, and the bidirectional non-isolated DC conversion module respectively have one or more switching tubes, and the working mode, working state and / or working point of each module are controlled by controlling the opening and closing of the switching tubes.

[0016] Furthermore, the control module is used to detect the voltage, current, frequency and / or temperature parameters of the DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module and the bidirectional non-isolated DC conversion module in real time, and control the operation of each module according to the set working mode and control rules, thereby controlling the photovoltaic energy storage micro-inverter.

[0017] Furthermore, the working modes include: photovoltaic grid-connected mode, photovoltaic off-grid mode, photovoltaic direct charging mode, AC charging mode and battery power supply mode.

[0018] In the second aspect, the utility model provides a photovoltaic energy storage system based on a bidirectional photovoltaic energy storage micro-inverter, the system comprising: at least one group of photovoltaic panels, a photovoltaic energy storage micro-inverter, a DC battery module, and an AC load and / or an AC power grid; the at least one group of photovoltaic panels are respectively connected to the input end of the photovoltaic energy storage micro-inverter, for outputting voltage to the photovoltaic energy storage micro-inverter; the output end of the bidirectional photovoltaic energy storage micro-inverter is respectively connected to the DC battery module, the AC load and / or the AC power grid, for inputting the voltage output by the photovoltaic string to the AC load or the AC power grid and charging the DC battery module.

[0019] Furthermore, each group of photovoltaic panels is composed of 1 to 2 photovoltaic panels connected in series or in parallel, and the output voltage range of each photovoltaic panel is 20 to 60V.

[0020] Furthermore, the DC battery module is a DC module of a storage battery, a battery pack, a fuel cell, a super capacitor and / or a UPS system, and the rated voltage of the DC battery module is 48V.

[0021] The beneficial effects of the technical solution provided by the embodiment of the utility model are as follows: the utility model discloses a bidirectional photovoltaic energy storage micro-inverter and a photovoltaic energy storage system, the system comprising: at least one group of photovoltaic panels, a photovoltaic energy storage micro-inverter, a DC battery module and an AC load and / or an AC power grid; the photovoltaic energy storage micro-inverter comprises at least one DC boost module, a DC bus, a bidirectional isolated DC boost module, a bidirectional DC / AC conversion module, a bidirectional non-isolated DC conversion module and a control module; the at least one group of photovoltaic panels are respectively connected to the input end of the at least one DC boost module, and the output end of the at least one DC boost module is connected to the DC bus, so as to convert the changing output voltage of the photovoltaic panel into a stable DC bus voltage; the DC bus is bidirectionally connected to the low-voltage side of the bidirectional isolated DC boost module, and the bidirectional isolated DC The high voltage side of the boost module is connected to the DC side of the bidirectional DC / AC conversion module, and the bidirectional isolated DC boost module is used to boost the DC bus voltage; the AC side of the bidirectional DC / AC conversion module is connected to the AC load or AC grid, and is used to convert the boosted DC bus voltage into an AC voltage and output it to the AC load or AC grid; the DC bus is bidirectionally connected to the high voltage side of the bidirectional non-isolated DC conversion module, and the low voltage side of the bidirectional non-isolated DC conversion module is bidirectionally connected to the DC battery module, and the bidirectional non-isolated DC conversion module is used to enable energy transmission between the DC battery module and the DC bus; the control module is respectively connected to the at least one DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module and the bidirectional non-isolated DC conversion module, and is used to control the working mode of each module. By adopting the above-mentioned photovoltaic energy storage micro-inverter, the circuit structure of the photovoltaic energy storage system is simple, the calculation amount of the control module is small, the processor performance requirements of the control module are low, and the production cost is reduced. In addition, by adding a photovoltaic energy storage micro inverter, it is possible to achieve zero voltage section and zero current opening under different conditions, greatly improving the adaptability of the photovoltaic energy storage system. Compared with the string photovoltaic energy storage inverter, each photovoltaic panel can be individually MPPT or shut down without high voltage on the DC side. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a structural schematic diagram of a bidirectional photovoltaic energy storage micro inverter provided by an embodiment of the utility model.

[0024] Figure 2 This is a topological diagram of a bidirectional AC / DC conversion module provided by an embodiment of the utility model.

[0025] Figure 3 It is a schematic structural diagram of a photovoltaic energy storage system based on a bidirectional photovoltaic energy storage micro-inverter provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clear, the implementation mode of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as commonly understood by technicians in the technical field of the present invention; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the directions or positions indicated by terms such as "length", "width", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", and "outside" are based on the directions or positions shown in the drawings, which are only for the convenience of description and cannot be understood as limitations on the present technical solution.

[0028] The terms "including" and "having" and any variations thereof in the specification and claims of the present utility model and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present utility model or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0029] In addition, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] Example

[0031] refer to Figure 1 and Figure 3 , which shows a schematic diagram of the structure of a bidirectional photovoltaic energy storage micro-inverter of the utility model and a schematic diagram of the structure of a photovoltaic energy storage system based on the bidirectional photovoltaic energy storage micro-inverter.

[0032] As an example, the system includes: at least one group of photovoltaic panels 1, a photovoltaic energy storage micro-inverter 2, a DC battery module 3 and an AC load 4 and / or an AC power grid 5; the photovoltaic energy storage micro-inverter 2 includes at least one DC boost module 210, a DC bus 220, a bidirectional isolated DC boost module 230, a bidirectional DC / AC conversion module 240, a bidirectional non-isolated DC conversion module 250 and a control module 260; the at least one group of photovoltaic panels 1 are respectively connected to the input end of the at least one DC boost module 210, and the output end of the at least one DC boost module 210 is connected to the DC bus 220, which is used to convert the changing output voltage of the photovoltaic panel to a stable DC bus voltage; the DC bus 220 is bidirectionally connected to the low voltage side of the bidirectional isolated DC boost module 230, and the high voltage side of the bidirectional isolated DC boost module 230 is connected to the bidirectional DC / AC conversion module 2 40, the bidirectional isolated DC boost module 230 is used to boost the DC bus voltage; the AC side of the bidirectional DC / AC conversion module 240 is connected to the AC load 4 or the AC grid 5, and is used to convert the boosted DC bus voltage into an AC voltage and output it to the AC load 4 or the AC grid 5; the DC bus 220 is bidirectionally connected to the high voltage side of the bidirectional non-isolated DC conversion module 250, and the low voltage side of the bidirectional non-isolated DC conversion module 250 is bidirectionally connected to the DC battery module 3, and the bidirectional non-isolated DC conversion module 250 is used to enable energy transmission between the DC battery module 3 and the DC bus 220; the control module 260 is respectively connected to the at least one DC boost module 210, the bidirectional isolated DC boost module 230, the bidirectional DC / AC conversion module 240 and the bidirectional non-isolated DC conversion module 250, and is used to control the working mode of each module. Specifically, the photovoltaic energy storage micro-inverter is a bidirectional full-bridge photovoltaic energy storage micro-inverter.

[0033] Preferably, each group of photovoltaic panels 1 is composed of 1 to 2 photovoltaic panels connected in series or in parallel, and the output voltage range of each photovoltaic panel is 20 to 60V. The number of photovoltaic panels is preferably 1 to 8, that is, the number of DC boost modules 210 is preferably 1 to 8. Specifically, the DC boost module 210 adopts the Boost boost circuit topology to convert the changing output voltage of the photovoltaic panel to a stable DC bus voltage. Each DC conversion module has a separate MPPT (Maximum Power Point Tracking) control, which controls the input voltage and current of the string by adjusting the duty cycle of the switch tube in the Boost boost circuit, so that the output power of the photovoltaic string is maximized.

[0034] Preferably, the DC battery module 3 is a DC module of a battery, a battery pack, a fuel cell, a supercapacitor and / or a UPS system, and its output voltage range is 42 to 54V, and preferably the rated voltage of the DC battery module is 48V.

[0035] Preferably, the voltage range of the DC bus 220 is 60-100V, preferably 70-80V.

[0036] Preferably, the bidirectional isolated DC boost module 230 is a DC boost circuit with an isolation transformer, adopts a bidirectional full-bridge circuit topology, and its output voltage is higher than the input voltage. Specifically, the bidirectional isolated DC boost module 230 adopts a bidirectional LLC resonant full-bridge circuit topology with an isolation transformer, the low-voltage side is connected to the DC bus 220, and the high-voltage side is connected to the bidirectional DC / AC conversion module 240. The circuit may include a low-voltage side full bridge, a high-frequency transformer and a high-voltage side full bridge, and also includes a low-voltage side resonant circuit and a high-voltage side resonant circuit.

[0037] Preferably, Figure 2 As shown, the bidirectional DC / AC conversion module 240 adopts a two-way staggered totem pole bridgeless PFC topology circuit, which has two working modes: rectification mode and inverter mode. When working in the rectification mode, the switch tubes S3 and S4 are alternately turned on or off in the positive and negative half-cycles of the AC power grid, and the switch tubes S1 and S2 are alternately formed with the AC side inductor L1 or L2 to form a Boost circuit to output a DC voltage. When working in the inverter mode, it works according to the full-bridge inverter topology structure, and the switch tubes S3 and S4 are alternately turned on or off in the positive and negative half-cycles of the AC power grid, and the switch tubes S1 and S2 are alternately formed with the AC side inductor L1 or L2 to form a Buck circuit to realize the function of inverter output. The two-way staggered totem pole bridgeless PFC topology circuit can not only realize the bidirectional conversion of inverter and rectification, but also reduce the ripple voltage and improve the DC power supply.

[0038] Preferably, the bidirectional non-isolated DC conversion module 250 adopts a bidirectional phase-shifted full-bridge circuit topology, and adopts a buck mode when working in the forward direction to charge the DC battery module 3 from the DC bus 220; and adopts a boost mode when working in the reverse direction to discharge from the DC battery module 3 to the DC bus 220. Specifically, the working mode of the bidirectional non-isolated DC conversion module 250 can be controlled by adjusting the phase difference between the front bridge and the rear bridge.

[0039] Preferably, the circuits of the DC boost module 210, the bidirectional isolated DC boost module 230, the bidirectional DC / AC conversion module 240, and the bidirectional non-isolated DC conversion module 250 are respectively provided with one or more switching tubes, and the working mode, working state and / or working point of each module are controlled by controlling the opening and closing of the switching tubes.

[0040] Preferably, the control module 260 is used to detect the voltage, current, frequency and / or temperature parameters of the DC boost module 210, the bidirectional isolated DC boost module 230, the bidirectional DC / AC conversion module 240 and the bidirectional non-isolated DC conversion module 250 in real time, and control the operation of each module according to the set working mode and control rules, thereby controlling the photovoltaic energy storage micro inverter. Among them, the working modes include: photovoltaic grid-connected mode, photovoltaic off-grid mode, photovoltaic direct charging mode, AC charging mode and battery power supply mode. Specifically, (1) photovoltaic grid-connected mode, the photovoltaic panel 1 provides DC power input, which is converted to DC bus voltage by the DC boost module 210, and then the low voltage through the DC bus 220 is boosted to the grid voltage (such as 360V) by the bidirectional isolated DC boost module 230, and then the DC is converted into AC grid-connected output to the AC grid 5 by the bidirectional DC / AC conversion module 240. (2) Photovoltaic off-grid mode: the photovoltaic panel 1 provides DC power input, which is converted to DC bus voltage by the DC boost module 210, and then the low voltage passing through the DC bus 220 is boosted to the grid voltage (such as 360V) by the bidirectional isolated DC boost module 230, and then inverted into AC by the bidirectional DC / AC conversion module 240, and the AC load 4 is powered off-grid. (3) Photovoltaic direct charging mode: the photovoltaic panel 1 provides DC power input, which is converted to DC bus voltage by the DC boost module 210, and then charged to the DC battery module 3 by the bidirectional non-isolated DC conversion module 250. (4) AC charging mode: the AC grid 5 provides AC power input, which is converted to DC voltage by the bidirectional DC / AC conversion module 240, and then transmitted to the DC bus 220 by the bidirectional isolated DC boost module 230, and then charged to the DC battery module 3 by the bidirectional non-isolated DC conversion module 250. (5) In the battery power supply mode, the DC battery module 3 provides DC power input, which is boosted to a DC bus voltage by the bidirectional non-isolated DC conversion module 250, and then inverted into AC by the bidirectional isolated DC boost module 230 and the bidirectional DC / AC conversion module 240 to supply power to the AC load 4.

[0041] Preferably, the control module 260 may also include: a touch display screen for setting the operation mode and setting parameters, and displaying the operation status and operation parameters; a communication module for communicating with a router, a host computer or a mobile device, receiving control instructions and sending operation data.

[0042] Preferably, each group of photovoltaic panels 1 is composed of two adjacent photovoltaic panels connected in parallel and then connected to a DC boost module 210 of a photovoltaic energy storage micro-inverter 2. The connection of two adjacent photovoltaic panels in parallel to one input of the micro-inverter has the following advantages compared with the connection of each photovoltaic panel to one input of the micro-inverter: (1) the system structure is simplified, which is easy to install and reduces the installation cost; (2) the number of DC boost modules is reduced by half, which is conducive to reducing costs; (3) the number of MPPT control paths is reduced by half, which reduces the requirements for the control module and the processing chip, and the stability of the control system is better; (4) the environment in which the adjacent photovoltaic panels are located is similar, and the performance of one-way MPPT control is basically equivalent to that of dual-way MPPT control.

[0043] The photovoltaic energy storage system in the above-mentioned embodiment disclosed by the utility model has a simple circuit structure, which makes the calculation amount of the control module small, and has low requirements on the processor performance of the control module, thus reducing the production cost. In addition, by adding a photovoltaic storage integrated inverter, it is possible to achieve zero voltage section and zero current opening under different conditions, which greatly improves the adaptability of the photovoltaic energy storage system. And compared with the string photovoltaic energy storage inverter, each photovoltaic panel can be individually MPPTed or shut down without high voltage on the DC side.

[0044] The above is only an embodiment of the utility model. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the utility model before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the utility model, several deformations and improvements can be made, which should also be regarded as the protection scope of the utility model, which will not affect the effect of the implementation of the utility model and the practicality of the patent. The protection scope required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to explain the content of the claims.

Claims

1. A bidirectional photovoltaic energy storage micro inverter, characterized in that: The photovoltaic energy storage micro inverter includes at least one DC boost module, a DC bus, a bidirectional isolated DC boost module, a bidirectional DC / AC conversion module, a bidirectional non-isolated DC conversion module and a control module; The input end of the at least one DC boost module is connected to the photovoltaic panel accordingly, and the output end of the at least one DC boost module is connected to the DC bus, so as to convert the changing output voltage of the photovoltaic panel into a stable DC bus voltage; The DC bus is bidirectionally connected to the low-voltage side of the bidirectional isolated DC boost module, the high-voltage side of the bidirectional isolated DC boost module is connected to the DC side of the bidirectional DC / AC conversion module, and the bidirectional isolated DC boost module is used to boost the DC bus voltage; The AC side of the bidirectional DC / AC conversion module is connected to an AC load or an AC grid, and is used to convert the boosted DC bus voltage into an AC voltage and output it to the AC load or the AC grid; The DC bus is bidirectionally connected to the high voltage side of the bidirectional non-isolated DC conversion module, the low voltage side of the bidirectional non-isolated DC conversion module is bidirectionally connected to the DC battery module, and the bidirectional non-isolated DC conversion module is used to enable energy transmission between the DC battery module and the DC bus; The control module is respectively connected to the at least one DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module and the bidirectional non-isolated DC conversion module, and is used to control the working mode of each module.

2. The bidirectional photovoltaic energy storage micro inverter according to claim 1 is characterized in that: The bidirectional isolated DC boost module is a DC boost circuit with an isolation transformer, adopts a bidirectional full-bridge circuit topology, and its output voltage is higher than the input voltage.

3. The bidirectional photovoltaic energy storage micro inverter according to claim 1 is characterized in that: The bidirectional DC / AC conversion module adopts a two-way staggered totem pole bridgeless PFC topology circuit and has two working modes: rectification mode and inverter mode.

4. The bidirectional photovoltaic energy storage micro inverter according to claim 1, characterized in that: The bidirectional non-isolated DC conversion module adopts a bidirectional phase-shifted full-bridge circuit topology, adopts a buck mode when working in the forward direction, and charges the DC battery module from the DC bus; and adopts a boost mode when working in the reverse direction, and discharges from the DC battery module to the DC bus.

5. The bidirectional photovoltaic energy storage micro inverter according to claim 1, characterized in that: The circuits of the DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module, and the bidirectional non-isolated DC conversion module are respectively provided with one or more switch tubes, and the working mode, working state and / or working point of each module are controlled by controlling the opening and closing of the switch tubes.

6. The bidirectional photovoltaic energy storage micro inverter according to claim 1, characterized in that: The control module is used to detect the voltage, current, frequency and / or temperature parameters of the DC boost module, the bidirectional isolated DC boost module, the bidirectional DC / AC conversion module and the bidirectional non-isolated DC conversion module in real time, and control the operation of each module according to the set working mode and control rules, thereby controlling the photovoltaic energy storage micro-inverter.

7. The bidirectional photovoltaic energy storage micro inverter according to claim 6, characterized in that: The working modes include: photovoltaic grid-connected mode, photovoltaic off-grid mode, photovoltaic direct charging mode, AC charging mode and battery power supply mode.

8. A photovoltaic energy storage system, characterized in that: The system is based on the bidirectional photovoltaic energy storage micro-inverter according to claim 1, comprising: at least one group of photovoltaic panels, a photovoltaic energy storage micro-inverter, a DC battery module, and an AC load and / or an AC grid; The at least one group of photovoltaic panels are respectively connected to the input terminals of the photovoltaic energy storage micro-inverter, and are used to output voltage to the photovoltaic energy storage micro-inverter; The output ends of the bidirectional photovoltaic energy storage micro-inverter are respectively connected to the DC battery module, the AC load and / or the AC power grid, and are used to input the voltage output by the photovoltaic string to the AC load or the AC power grid and to charge the DC battery module.

9. The photovoltaic energy storage system according to claim 8, characterized in that: Each group of photovoltaic panels is composed of 1 to 2 photovoltaic panels connected in series or in parallel, and the output voltage range of each photovoltaic panel is 20 to 60V.

10. The photovoltaic energy storage system according to claim 8, characterized in that: The DC battery module is a DC module of a storage battery, a battery pack, a fuel cell, a super capacitor and / or a UPS system, and the rated voltage of the DC battery module is 48V.

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