Photovoltaic energy storage inverter and control method thereof

Abstract

The invention discloses a photovoltaic energy storage inverter and a control method thereof. Compatible adaptation to a high-voltage battery system and a low-voltage battery system is achieved. The photovoltaic energy storage inverter comprises two battery access ports, a photovoltaic access port, a load access port, a commercial power access port, a switching module, two bidirectional DC-DC conversion modules, a bus capacitor, a DC-AC conversion module and an MPPT module. The switching module is connected with the low-voltage side of the first bidirectional DC-DC conversion module, the high-voltage side of the second bidirectional DC-DC conversion module, the first battery access port and the second battery access port; the high-voltage side of the first bidirectional DC-DC conversion module, the low-voltage side of the second bidirectional DC-DC conversion module, the direct-current side of the DC-AC conversion module and the output side of the MPPT module are connected to the bus capacitor in parallel. The input side of the MPPT module is connected to the photovoltaic access port; the AC side of the DC-AC conversion module is connected to the load access port and the commercial power access port.

Description

Technical Field

[0001] This application relates to the field of photovoltaic energy storage technology, and in particular to a photovoltaic energy storage inverter and its control method. Background Technology

[0002] Against the backdrop of escalating environmental pollution, the development and utilization of clean energy has become an inevitable trend in the global energy transition. Solar energy, as a typical renewable and clean energy source, has become an important development direction in the new energy field due to its near-infinite reserves and zero pollution emissions. Photovoltaic modules achieve efficient conversion of solar energy into electrical energy through the photoelectric conversion effect, and photovoltaic energy storage systems built upon this technology have already been deployed on a large scale in diverse scenarios such as residential buildings and industrial and commercial parks.

[0003] In a photovoltaic energy storage system, the energy storage inverter serves as the core hub, responsible for regulating the energy flow between photovoltaic modules, energy storage batteries, and the mains power, as well as intelligently managing the power supply to the load. Its operating logic follows the principle of optimal energy utilization: when sunlight is abundant, the power generated by the photovoltaic modules is prioritized for the load, with excess power used to charge the energy storage batteries; when sunlight is insufficient, the energy stored in the batteries is released to continue supplying power to the load; and when the energy storage batteries are low on power and there is no photovoltaic power generation to supplement it, the system switches to mains power to supply the load.

[0004] With the continuous increase in load power demand, the existing capacity of energy storage batteries can no longer meet the needs, making energy storage battery capacity expansion a rigid requirement. Due to the limitations of industry standard capacity specifications for single battery cells, energy storage battery capacity expansion solutions are mainly divided into two categories: one is the high-voltage battery system solution, which increases the total capacity of the battery system by connecting energy storage battery packs in series, commonly known as high-voltage stacked batteries (150V~800V); the other is the low-voltage battery system solution, which increases the total capacity of the battery system by connecting energy storage battery packs in parallel, commonly known as 48V batteries. However, existing energy storage inverters have fixed voltage adaptation parameters for their battery input ports at the factory, only compatible with one type of battery system (high-voltage battery system or low-voltage battery system). This limits the applicable scenarios of energy storage inverters—after purchasing a photovoltaic energy storage inverter, customers can only choose the adaptation type between high-voltage and low-voltage battery systems based on its port specifications, increasing the selection cost for users and hindering the market promotion of the product. Summary of the Invention

[0005] In view of the above problems, this application provides a photovoltaic energy storage inverter and its control method to achieve compatibility and adaptation of the photovoltaic energy storage inverter with both high-voltage and low-voltage battery systems. The specific solution is as follows:

[0006] The first aspect of this application provides a photovoltaic energy storage inverter, including: a controller, a first battery access port, a second battery access port, a photovoltaic access port, a load access port, a mains power access port, a switching module, a first bidirectional DC-DC conversion module, a second bidirectional DC-DC conversion module, a bus capacitor, a DC-AC conversion module, and an MPPT module;

[0007] The switching module is connected to the low-voltage side of the first bidirectional DC-DC converter module, the high-voltage side of the second bidirectional DC-DC converter module, the first battery access port, and the second battery access port.

[0008] The high-voltage side of the first bidirectional DC-DC converter module, the low-voltage side of the second bidirectional DC-DC converter module, the DC side of the DC-AC converter module, and the output side of the MPPT module are connected in parallel to the bus capacitor.

[0009] The input side of the MPPT module is connected to the photovoltaic access port; the AC side of the DC-AC conversion module is connected to the load access port and the mains power access port.

[0010] The controller is used to detect the access status of the first battery access port and the second battery access port:

[0011] When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0012] When it is detected that the second battery access port is connected to a low-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0013] When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0014] When it is detected that the second battery access port is connected to the high-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0015] When it is detected that both the first battery access port and the second battery access port are connected to the low-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the low-voltage side of the first bidirectional DC-DC converter module.

[0016] When it is detected that both the first battery access port and the second battery access port are connected to the high-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the high-voltage side of the second bidirectional DC-DC converter module;

[0017] When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port is connected to a high-voltage battery system, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module and the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0018] When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port is connected to a low-voltage battery system, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module and the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0019] In one possible implementation, the switching module includes: switch SW1, switch SW2, switch SW3, switch SW4, switch SW5, switch SW6, switch SW7 and switch SW8;

[0020] One end of switch SW1 and one end of switch SW2 are both connected to the positive terminal of the first battery access port, one end of switch SW3 and one end of switch SW4 are both connected to the positive terminal of the second battery access port, one end of switch SW5 and one end of switch SW6 are both connected to the negative terminal of the second battery access port, and one end of switch SW7 and one end of switch SW8 are both connected to the negative terminal of the first battery access port.

[0021] The other ends of switches SW1 and SW3 are both connected to the low-voltage positive terminal of the first bidirectional DC-DC converter module, the other ends of switches SW2 and SW4 are both connected to the high-voltage positive terminal of the second bidirectional DC-DC converter module, the other ends of switches SW5 and SW7 are both connected to the low-voltage negative terminal of the first bidirectional DC-DC converter module, and the other ends of switches SW6 and SW8 are both connected to the high-voltage negative terminal of the second bidirectional DC-DC converter module.

[0022] In one possible implementation, the switches in the switching module are of the type of relay, contactor, or air switch.

[0023] In one possible implementation, the first bidirectional DC-DC converter module is a bidirectional DC-DC converter module with electrical isolation function, and the second bidirectional DC-DC converter module is a full-bridge bidirectional Buck-Boost module.

[0024] In one possible implementation, the first bidirectional DC-DC converter module includes: capacitor C1, transistor Q1, transistor Q2, transistor Q3, transistor Q4, transformer T1, resonant capacitor C2, transistor Q5, transistor Q6, transistor Q7, and transistor Q8.

[0025] The high-voltage terminal of capacitor C1 is connected to the low-voltage positive terminal of the first bidirectional DC-DC converter module, the input terminal of transistor Q1, and the input terminal of transistor Q2.

[0026] The low-voltage terminal of capacitor C1 is connected to the low-voltage side negative terminal of the first bidirectional DC-DC converter module, the output terminal of transistor Q3, and the output terminal of transistor Q4.

[0027] The output terminal of transistor Q1, the input terminal of transistor Q3, and one end of the primary winding of transformer T1 are connected; the output terminal of transistor Q2, the input terminal of transistor Q4, and the other end of the primary winding of transformer T1 are connected.

[0028] One end of the secondary winding of transformer T1 is connected to one end of resonant capacitor C2, and the other end of resonant capacitor C2 is connected to the output terminal of transistor Q5 and the input terminal of transistor Q7; the other end of the secondary winding of transformer T1 is connected to the output terminal of transistor Q6 and the input terminal of transistor Q8.

[0029] The input terminals of transistors Q5 and Q6 are connected to the positive high-voltage side of the first bidirectional DC-DC converter module, and the output terminals of transistors Q7 and Q8 are connected to the negative high-voltage side of the first bidirectional DC-DC converter module.

[0030] In one possible implementation, the second bidirectional DC-DC converter module includes: capacitor C4, transistor Q9, transistor Q10, inductor L1, transistor Q11, and transistor Q12;

[0031] The high-voltage terminal of capacitor C4 is connected to the positive terminal of the high-voltage side of the second bidirectional DC-DC converter module and the input terminal of transistor Q9. The low-voltage terminal of capacitor C4 is connected to the negative terminal of the high-voltage side of the second bidirectional DC-DC converter module and the output terminal of transistor Q10. The output terminal of transistor Q9 is connected to the input terminal of transistor Q10 and one end of inductor L1. The other end of inductor L1 is connected to the input terminal of transistor Q11 and the output terminal of transistor Q12. The output terminal of transistor Q11 is connected to the output terminal of transistor Q10 and the negative terminal of the low-voltage side of the second bidirectional DC-DC converter module. The input terminal of transistor Q12 is connected to the positive terminal of the low-voltage side of the second bidirectional DC-DC converter module.

[0032] In one possible implementation, the MPPT module is a Boost circuit; the Boost circuit includes capacitor C6, inductor L4, transistor Q19, diode D1 and capacitor C7;

[0033] The high-voltage terminal of capacitor C6 is connected to one end of inductor L4 and the positive terminal of the input side of the Boost circuit. The other end of inductor L4 is connected to the input terminal of transistor Q19 and the anode of diode D1. The cathode of diode D1 is connected to the high-voltage terminal of capacitor C7. The low-voltage terminal of capacitor C6 is connected to the negative terminal of the input terminal of the Boost circuit, the negative terminal of the output terminal of the Boost circuit, the output terminal of transistor Q19, and the low-voltage terminal of capacitor C7.

[0034] In one possible implementation, the DC-AC conversion module includes: transistor Q13, transistor Q14, transistor Q15, transistor Q16, transistor Q17, transistor Q18, inductor L2, inductor L3, and capacitor C5.

[0035] The input terminals of transistors Q13 and Q14 are connected to the positive DC side of the DC-AC converter module. The output terminals of transistors Q15 and Q16 are connected to the negative DC side of the DC-AC converter module. The output terminal of transistor Q13, the input terminal of transistor Q15, the input terminal of transistor Q17, and one end of inductor L2 are connected. The output terminal of transistor Q14, the input terminal of transistor Q16, the input terminal of transistor Q18, and one end of inductor L3 are connected. The output terminal of transistor Q17 is connected to the output terminal of transistor Q18. The other end of inductor L2 is connected to one end of capacitor C5. The other end of inductor L3 is connected to the other end of capacitor C5. Capacitor C5 is connected to the AC power input port and the load input port.

[0036] In one possible implementation, the transistors in the photovoltaic energy storage inverter are either MOSFETs or IGBTs.

[0037] A second aspect of this application provides a control method for a photovoltaic energy storage inverter. The photovoltaic energy storage inverter includes: a controller, a first battery access port, a second battery access port, a photovoltaic access port, a load access port, a mains access port, a switching module, a first bidirectional DC-DC converter module, a second bidirectional DC-DC converter module, a bus capacitor, a DC-AC converter module, and an MPPT module. The switching module is connected to the low-voltage side of the first bidirectional DC-DC converter module, the high-voltage side of the second bidirectional DC-DC converter module, the first battery access port, and the second battery access port. The high-voltage side of the first bidirectional DC-DC converter module, the low-voltage side of the second bidirectional DC-DC converter module, the DC side of the DC-AC converter module, and the output side of the MPPT module are connected in parallel to the bus capacitor. The input side of the MPPT module is connected to the photovoltaic access port. The AC side of the DC-AC converter module is connected to the load access port and the mains access port.

[0038] The method is applied to the controller, and the method includes:

[0039] Detect the access status of the first battery access port and the second battery access port;

[0040] When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0041] When it is detected that the second battery access port is connected to a low-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0042] When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0043] When it is detected that the second battery access port is connected to the high-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0044] When it is detected that both the first battery access port and the second battery access port are connected to the low-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the low-voltage side of the first bidirectional DC-DC converter module.

[0045] When it is detected that both the first battery access port and the second battery access port are connected to the high-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the high-voltage side of the second bidirectional DC-DC converter module;

[0046] When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port is connected to a high-voltage battery system, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module and the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0047] When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port is connected to a low-voltage battery system, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module and the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0048] By employing the aforementioned technical solution, the photovoltaic energy storage inverter provided in this application, through its hardware design of dual battery access ports, dual DC-DC conversion modules, and a switching module, combined with the controller's control logic for the internal switches of the switching module, can achieve flexible switching connections between the two battery access ports and the two DC-DC conversion modules. This allows the same photovoltaic energy storage inverter to adapt to various access scenarios: single connection to a high-voltage battery system, single connection to a low-voltage battery system, parallel connection to a dual low-voltage battery system, parallel connection to a dual high-voltage battery system, or simultaneous connection to both high and low-voltage battery systems. This reduces the user's selection costs, broadens the applicable scenarios for photovoltaic energy storage inverters, and promotes the market promotion of the product. Attached Figure Description

[0049] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0050] Figure 1 This application provides a structural schematic diagram of a photovoltaic energy storage inverter;

[0051] Figure 2 for Figure 1 The schematic diagram shows the switching module, the first bidirectional DC-DC conversion module, and the second bidirectional DC-DC conversion module in the photovoltaic energy storage inverter.

[0052] Figure 3 for Figure 1The schematic diagram of the MPPT module in the photovoltaic energy storage inverter is shown.

[0053] Figure 4 for Figure 1 The diagram shows the schematic of the DC-AC conversion module in the photovoltaic energy storage inverter. Detailed Implementation

[0054] In order to ensure the accuracy of the citations and the fluency of reading, the key technical terms, abbreviations or acronyms used in the text are summarized and explained as follows:

[0055] DC-DC: Direct Current to Direct Current;

[0056] DC-AC: Direct Current to Alternating Current;

[0057] MPPT: Maximum Power Point Tracking;

[0058] MOSFET: Metal-Oxide-Semiconductor Field-Effect Transistor, abbreviated as MOS transistor;

[0059] IGBT: Insulated Gate Bipolar Transistor.

[0060] This application provides a photovoltaic energy storage inverter designed to achieve compatibility and adaptability with both high-voltage and low-voltage battery systems. Specifically, through a hardware design featuring dual battery input ports, dual DC-DC conversion modules, and a switching module, combined with the controller's control logic for the internal switches of the switching module, flexible switching connections between the two battery input ports and the two DC-DC conversion modules can be achieved. This allows the same photovoltaic energy storage inverter to adapt to various access scenarios: single connection to a high-voltage battery system, single connection to a low-voltage battery system, parallel connection to two low-voltage battery systems, parallel connection to two high-voltage battery systems, or simultaneous connection to both high- and low-voltage battery systems. This reduces user selection costs, broadens the applicable scenarios for photovoltaic energy storage inverters, and promotes product market adoption.

[0061] The following detailed description, with reference to the accompanying drawings, describes a photovoltaic energy storage inverter provided in an embodiment of this application. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in this application are also applicable to similar technical problems.

[0062] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0063] See Figure 1 This application provides a photovoltaic energy storage inverter, including: a controller ( Figure 1 (Not shown in the diagram) First battery access port 1, second battery access port 2, photovoltaic access port 3, load access port 4, mains power access port 5, switching module 6, first bidirectional DC-DC converter module 7, second bidirectional DC-DC converter module 8, bus capacitor C3, DC-AC converter module 9 and MPPT module 10;

[0064] The switching module 6 is connected to the low-voltage side of the first bidirectional DC-DC converter module 7, the high-voltage side of the second bidirectional DC-DC converter module 8, the first battery access port 1, and the second battery access port 2.

[0065] The high-voltage side of the first bidirectional DC-DC converter module 7, the low-voltage side of the second bidirectional DC-DC converter module 8, the DC side of the DC-AC converter module 9, and the output side of the MPPT module 10 are connected in parallel to the bus capacitor C3.

[0066] The input side of the MPPT module 10 is connected to the photovoltaic access port 3; the AC side of the DC-AC conversion module 9 is connected to the load access port 4 and the mains power access port 5.

[0067] The controller is connected to the first battery access port 1, the second battery access port 2, the photovoltaic access port 3, the load access port 4, the mains power access port 5, the switching module 6, the first bidirectional DC-DC converter module 7, the second bidirectional DC-DC converter module 8, the bus capacitor C3, the DC-AC converter module 9, and the MPPT module 10. It is used to detect the access status of the first battery access port 1, the second battery access port 2, the photovoltaic access port 3, the load access port 4, and the mains power access port 5, and to control the working status of the switching module 6, the first bidirectional DC-DC converter module 7, the second bidirectional DC-DC converter module 8, the DC-AC converter module 9, and the MPPT module 10 in a coordinated manner based on the detection results. This enables the regulation of energy flow between the photovoltaic modules, the battery system, the mains power, and the load, as well as the intelligent management of the power supply to the load.

[0068] The control logic of the controller for the switching module 6 is as follows: The controller is used to detect the connection status of the first battery access port 1 and the second battery access port 2 (no battery system connected, connected to a low-voltage battery system, or connected to a high-voltage battery system). Based on the detection result, the controller controls the internal switch of the switching module 6 to connect the corresponding battery access port to the adapted bidirectional DC-DC converter module. There are eight connection configurations in total:

[0069] Connection Configuration 1: When it is detected that the first battery access port 1 is connected to a low-voltage battery system and the second battery access port 2 has no voltage input (i.e. no battery system is connected), the control switching module 6 connects the first battery access port 1 to the low-voltage side of the first bidirectional DC-DC converter module 7 to charge and discharge the low-voltage battery system.

[0070] Connection Configuration 2: When it is detected that the second battery access port 2 is connected to the low-voltage battery system and the first battery access port 1 has no voltage input, the control switching module 6 connects the second battery access port 2 to the low-voltage side of the first bidirectional DC-DC converter module 7 to charge and discharge the low-voltage battery system.

[0071] Connection Configuration 3: When it is detected that the first battery access port 1 is connected to the high-voltage battery system and the second battery access port 2 has no voltage input, the control switching module 6 connects the first battery access port 1 to the high-voltage side of the second bidirectional DC-DC converter module 8 to charge and discharge the high-voltage battery system.

[0072] Connection Configuration 4: When it is detected that the second battery access port 2 is connected to the high-voltage battery system and the first battery access port 1 has no voltage input, the control switching module 6 connects the second battery access port 2 to the high-voltage side of the second bidirectional DC-DC converter module 8 to charge and discharge the high-voltage battery system.

[0073] Connection Configuration 5: When it is detected that both the first battery access port 1 and the second battery access port 2 are connected to the low-voltage battery system, the control switching module 6 connects the first battery access port 1 and the second battery access port 2 in parallel to the low-voltage side of the first bidirectional DC-DC converter module 7, and charges and discharges the two low-voltage battery systems through the first bidirectional DC-DC converter module 7.

[0074] Connection Configuration 6: When it is detected that both the first battery access port 1 and the second battery access port 2 are connected to the high-voltage battery system, the control switching module 6 connects the first battery access port 1 and the second battery access port 2 in parallel to the high-voltage side of the second bidirectional DC-DC converter module 8, and charges and discharges the two high-voltage battery systems through the second bidirectional DC-DC converter module 8.

[0075] Connection Configuration 7: When it is detected that the first battery access port 1 is connected to the low-voltage battery system and the second battery access port 2 is connected to the high-voltage battery system, the control switching module 6 connects the first battery access port 1 to the low-voltage side of the first bidirectional DC-DC converter module 7 and the second battery access port 2 to the high-voltage side of the second bidirectional DC-DC converter module 8, so as to charge and discharge the low-voltage battery system and the high-voltage battery system respectively.

[0076] Connection Configuration 8: When it is detected that the first battery access port 1 is connected to the high-voltage battery system and the second battery access port 2 is connected to the low-voltage battery system, the control switching module 6 connects the first battery access port 1 to the high-voltage side of the second bidirectional DC-DC converter module 8 and the second battery access port 2 to the low-voltage side of the first bidirectional DC-DC converter module 7, so as to charge and discharge the high-voltage battery system and the low-voltage battery system respectively.

[0077] Below, on Figure 1 The working principle of the scheme shown is compatible with both high-voltage and low-voltage battery systems.

[0078] Figure 1 The solution shown combines hardware architecture and software control logic to achieve compatibility and adaptation of photovoltaic energy storage inverters with high and low voltage battery systems.

[0079] From a hardware architecture perspective, Figure 1 The scheme shown constructs a hardware architecture that supports multiple scenarios by setting up a first and a second battery access port, paired with a first and a second bidirectional DC-DC converter module adapted to low-voltage and high-voltage battery systems respectively, and using a switching module 6 as an intermediate connection hub: the dual battery access ports can be connected to the battery system independently or simultaneously, the first and second bidirectional DC-DC converter modules correspond to low-voltage and high-voltage conversion requirements respectively, and the switching module 6 is responsible for dynamically switching the connection relationship between the battery access port and the bidirectional DC-DC converter module.

[0080] From the perspective of software control logic, the controller monitors the connection status of the first and second battery access ports in real time, including whether a battery system is connected and whether it is a low-voltage or high-voltage battery system. Based on the detection results, the controller adjusts the connection status of the switching module 6 to establish a path between the battery access port and the adapted bidirectional DC-DC converter module: when a single port is connected to a low-voltage battery system, it is connected to the low-voltage side of the first bidirectional DC-DC converter module 7; when a single port is connected to a high-voltage battery system, it is connected to the high-voltage side of the second bidirectional DC-DC converter module 8; when both ports are connected to the same type of battery system (both low-voltage or both high-voltage), the two are connected in parallel through the switching module 6 and then connected to the corresponding bidirectional DC-DC converter module to achieve coordinated charging and discharging; when both ports are connected to different types of battery systems (one low-voltage and one high-voltage), they are connected to the corresponding sides of the first and second bidirectional DC-DC converter modules respectively to achieve independent charging and discharging control.

[0081] Through this logical closed loop of "state detection - adaptation switching - corresponding charging and discharging", Figure 1 The solution shown can cover various scenarios, such as connecting to a high-voltage battery system alone, connecting to a low-voltage battery system alone, connecting to a dual low-voltage battery system in parallel, connecting to a dual high-voltage battery system in parallel, or connecting to both high-voltage and low-voltage battery systems simultaneously. This allows the same photovoltaic energy storage inverter to be compatible with different types of battery systems without hardware modifications, thereby reducing the selection cost for users, expanding the applicable scenarios of photovoltaic energy storage inverters, and promoting the market promotion of the products.

[0082] It should be noted that the terms "high-voltage battery system" and "low-voltage battery system" in this article are relative concepts. The "high" in high-voltage battery system is relative to the "low" in low-voltage battery system, and also to the "closeness" of the bus voltage (the voltage of high-voltage battery system is close to or slightly higher than the bus voltage, while the voltage of low-voltage battery system is significantly lower than the bus voltage).

[0083] In one possible implementation, see Figure 2The switching module 6 includes: switches SW1, SW2, SW3, SW4, SW5, SW6, SW7, and SW8; one end of switch SW1 and one end of switch SW2 are connected to the positive terminal of the first battery access port 1, one end of switch SW3 and one end of switch SW4 are connected to the positive terminal of the second battery access port 2, one end of switch SW5 and one end of switch SW6 are connected to the negative terminal of the second battery access port 2, and one end of switch SW7 and one end of switch SW8 are connected to the negative terminal of the first battery access port 1; the other end of switch SW1 and the other end of switch SW3 are connected to the low-voltage positive terminal of the first bidirectional DC-DC converter module 7, the other end of switch SW2 and the other end of switch SW4 are connected to the high-voltage positive terminal of the second bidirectional DC-DC converter module 8, the other end of switch SW5 and the other end of switch SW7 are connected to the low-voltage negative terminal of the first bidirectional DC-DC converter module 7, and the other end of switch SW6 and the other end of switch SW8 are connected to the high-voltage negative terminal of the second bidirectional DC-DC converter module 8.

[0084] Specifically, based on Figure 2 The provided switching module 6 is configured in the following ways: Connection configuration 1 is implemented by closing switches SW1 and SW7; Connection configuration 2 is implemented by closing switches SW3 and SW5; Connection configuration 3 is implemented by closing switches SW2 and SW8; Connection configuration 4 is implemented by closing switches SW4 and SW6; Connection configuration 5 is implemented by closing switches SW1, SW3, SW5, and SW7; Connection configuration 6 is implemented by closing switches SW2, SW4, SW6, and SW8; Connection configuration 7 is implemented by closing switches SW4, SW6, SW1, and SW7; and Connection configuration 8 is implemented by closing switches SW2, SW8, SW3, and SW5.

[0085] For switches SW1 to SW8, the type of each switch can be a relay, contactor, or air switch, and there are no restrictions.

[0086] In one possible implementation, based on any of the photovoltaic energy storage inverters provided above, the first bidirectional DC-DC converter module 7 is a bidirectional DC-DC converter module with electrical isolation function, such as a DAB circuit (dual active bridge circuit) or an LLC resonant converter circuit; the second bidirectional DC-DC converter module 8 is a full-bridge bidirectional Buck-Boost module.

[0087] Specifically, the difference in topology selection between the two DC-DC converter modules stems from the divergence in application scenarios and performance requirements. For the high input current characteristic of low-voltage battery systems, the first bidirectional DC-DC converter module 7 adopts an isolated design, using a high-frequency transformer for voltage boosting. Its advantage lies in achieving electrical isolation between input and output. The low-voltage side can utilize transistors with low withstand voltage ratings and low on-resistance to reduce losses, while the high-voltage side is suited for high-voltage, low-current transistor devices. However, this design has limitations such as a fixed boost factor and a narrow input voltage range. The second bidirectional DC-DC converter module 8, to accommodate a wide input voltage range, adopts a full-bridge bidirectional Buck-Boost topology. The two bidirectional DC-DC converter modules work together to flexibly adapt to battery systems with different voltage levels.

[0088] In one possible implementation, see still Figure 2 The first bidirectional DC-DC converter module 7 (including electrical isolation function) includes: capacitor C1, transistors Q1, Q2, Q3, Q4, transformer T1, resonant capacitor C2, transistors Q5, Q6, Q7, and Q8; the high-voltage terminal of capacitor C1 is connected to the positive terminal of the low-voltage side of the first bidirectional DC-DC converter module 7, the input terminal of transistor Q1, and the input terminal of transistor Q2; the low-voltage terminal of capacitor C1 is connected to the negative terminal of the low-voltage side of the first bidirectional DC-DC converter module 7, the output terminal of transistor Q3, and the output terminal of transistor Q4; the output terminal of transistor Q1, the input terminal of transistor Q3, and the transformer T1... One end of the primary winding is connected to the output terminal of transistor Q2, the input terminal of transistor Q4, and the other end of the primary winding of transformer T1; one end of the secondary winding of transformer T1 is connected to one end of resonant capacitor C2, and the other end of resonant capacitor C2, the output terminal of transistor Q5, and the input terminal of transistor Q7 are connected; the other end of the secondary winding of transformer T1, the output terminal of transistor Q6, and the input terminal of transistor Q8 are connected; the input terminals of transistor Q5 and transistor Q6 are connected to the positive terminal of the high-voltage side of the first bidirectional DC-DC converter module 7, and the output terminals of transistor Q7 and transistor Q8 are connected to the negative terminal of the high-voltage side of the first bidirectional DC-DC converter module 7.

[0089] Specifically Figure 2The working principle of the first bidirectional DC-DC converter module 7 is as follows: The turns ratio of the primary winding to the secondary winding of transformer T1 is 1:n (n is a positive integer greater than 1), and the resonant capacitor C2 participates in the resonant regulation of energy conversion. When the battery system connected to the low-voltage side of the first bidirectional DC-DC converter module 7 discharges, the controller adjusts the bus voltage Ubus (voltage of bus capacitor C3) by coordinating the external modules (such as DC-AC converter module 9, MPPT module 10, etc.) connected to the bus capacitor C3 in the photovoltaic energy storage inverter, so that the voltage Ubat of the battery system satisfies Ubat > Ubus / n; under this voltage condition, the controller controls transistors Q1, Q4, Q5, and Q8 to be switched on and off synchronously, and transistors Q2, Q3, Q6, and Q7 to be switched on and off synchronously, and the driving signals of the two sets of transistors are complementary. Through the alternating switching of the switching states, in conjunction with the turns ratio of transformer T1 and the resonant capacitor C2, the battery energy is transferred to the bus side. When the battery system is charging, the controller adjusts the external module to make Ubus satisfy Ubat < Ubus / n. The transistors maintain the same control logic (Q1, Q4, Q5, Q8 and Q2, Q3, Q6, Q7 are turned on and off synchronously and the drive signals are complementary). The energy flow is reversed, realizing the transfer of energy from the bus side to the battery system.

[0090] In one possible implementation, see still Figure 2 The second bidirectional DC-DC converter module 8 (using a full-bridge bidirectional Buck-Boost topology) includes: capacitor C4, transistor Q9, transistor Q10, inductor L1, transistor Q11, and transistor Q12. The high-voltage terminal of capacitor C4 is connected to the positive terminal of the high-voltage side of the second bidirectional DC-DC converter module 8 and the input terminal of transistor Q9. The low-voltage terminal of capacitor C4 is connected to the negative terminal of the high-voltage side of the second bidirectional DC-DC converter module 8 and the output terminal of transistor Q10. The output terminal of transistor Q9 is connected to the input terminal of transistor Q10 and one end of inductor L1. The other end of inductor L1 is connected to the input terminal of transistor Q11 and the output terminal of transistor Q12. The output terminal of transistor Q11 is connected to the output terminal of transistor Q10 and the negative terminal of the low-voltage side of the second bidirectional DC-DC converter module 8. The input terminal of transistor Q12 is connected to the positive terminal of the low-voltage side of the second bidirectional DC-DC converter module 8.

[0091] Specifically Figure 2 The working principle of the second bidirectional DC-DC converter module 8 shown is as follows:

[0092] When the battery system connected to the high-voltage side of the second bidirectional DC-DC converter module 8 discharges, the controller achieves voltage adaptation by controlling the switching of transistors: if the voltage Ubat of the battery system is higher than the bus voltage Ubus, the second bidirectional DC-DC converter module 8 operates in Buck mode. At this time, transistors Q12 are normally closed, Q11 is normally open, and Q9 and Q10 are complementaryly turned on. The energy on the high-voltage side is stepped down and transferred to the bus through the energy storage-release process of inductor L1. If Ubat is lower than Ubus, the second bidirectional DC-DC converter module 8 switches to Boost mode. At this time, Q9 and Q12 are synchronously turned on, and Q10 and Q11 are synchronously turned off (the two sets of drive signals are complementary). The low-voltage energy is boosted and injected into the bus by utilizing the energy storage characteristics of inductor L1.

[0093] When the battery system is charging, the operating mode and control logic of the second bidirectional DC-DC converter module 8 are adapted in reverse according to the voltage relationship: if Ubat is higher than Ubus, the second bidirectional DC-DC converter module 8 operates in Boost mode. At this time, Q10 and Q11 are synchronously turned on, and Q9 and Q12 are synchronously turned off (the two sets of drive signals are complementary). The energy of the bus is boosted and injected into the battery system through the energy storage and release of inductor L1. If Ubat is lower than Ubus, the second bidirectional DC-DC converter module 8 switches to Buck mode. At this time, Q12 is normally closed, Q11 is normally open, and Q9 and Q10 are complementaryly turned on. The energy of the bus is stepped down and transferred to the battery system through the energy conversion of inductor L1.

[0094] In one possible implementation, see Figure 3 Based on any of the photovoltaic energy storage inverters provided above, the MPPT module 10 is a Boost circuit. The Boost circuit includes a capacitor C6, an inductor L4, a transistor Q19, a diode D1, and a capacitor C7. The high-voltage terminal of capacitor C6 is connected to one end of inductor L4 and the positive terminal of the input side of the Boost circuit. The other end of inductor L4 is connected to the input terminal of transistor Q19 and the anode of diode D1. The cathode of diode D1 is connected to the high-voltage terminal of capacitor C7. The low-voltage terminal of capacitor C6 is connected to the negative terminal of the input side of the Boost circuit, the negative terminal of the output side of the Boost circuit, the output terminal of transistor Q19, and the low-voltage terminal of capacitor C7.

[0095] Specifically Figure 3The working principle of the Boost circuit shown is as follows: When the controller detects that the voltage at the photovoltaic input port 3 is higher than the set minimum operating voltage, it controls the on / off state of Q19 to achieve boost conversion and maximum power point tracking: When the controller outputs a high-level signal, Q19 is turned on. At this time, the photovoltaic input voltage forms a loop through Q19, and inductor L4 begins to store energy. The polarity of the voltage across its terminals is positive on the left and negative on the right, and the current increases linearly. Since diode D1 is cut off due to reverse voltage across Q19, capacitor C7 releases the stored energy to bus capacitor C3 to maintain the output. When the controller outputs a low-level signal, Q19 is cut off. Inductor L4 generates a reverse induced electromotive force (polarity changes to positive on the right and negative on the left) because the current cannot change abruptly. This electromotive force is superimposed on the photovoltaic input voltage, causing diode D1 to conduct in the forward direction. At this time, the photovoltaic input and inductor L4 charge capacitor C7 together (while simultaneously supplying power to bus capacitor C3), completing the energy transfer. The controller dynamically adjusts the duty cycle of Q19 to make the photovoltaic module work at the maximum power point, realizing the photovoltaic maximum power point tracking function. Capacitor C6 is used to stabilize the photovoltaic input voltage; capacitor C7 is the output filter capacitor.

[0096] In one possible implementation, see Figure 4 Based on any of the photovoltaic energy storage inverters provided above, the DC-AC conversion module 9 includes: transistors Q13, Q14, Q15, Q16, Q17, Q18, inductor L2, inductor L3, and capacitor C5; the input terminals of transistors Q13 and Q14 are connected to the positive DC side of the DC-AC conversion module 9, the output terminals of transistors Q15 and Q16 are connected to the negative DC side of the DC-AC conversion module 9, the output terminal of transistor Q13, the input terminal of transistor Q15, the input terminal of transistor Q17, and one end of inductor L2 are connected, the output terminal of transistor Q14, the input terminal of transistor Q16, the input terminal of transistor Q18, and one end of inductor L3 are connected, the output terminal of transistor Q17 is connected to the output terminal of transistor Q18, the other end of inductor L2 is connected to one end of capacitor C5, the other end of inductor L3 is connected to the other end of capacitor C5, and capacitor C5 is connected to the mains input port 5 and the load input port 4.

[0097] Specifically Figure 4 The operating states of the DC-AC converter module 9 shown can be divided into the following four stages according to the grid voltage polarity and freewheeling stage:

[0098] Stage 1. During the positive half-cycle of the grid voltage, the controller drives transistors Q13 and Q16 to conduct, while the remaining transistors are turned off. The current path is: bus capacitor C3 → Q13 → inductor L2 → load → inductor L3 → Q16 → bus capacitor C3, realizing the positive output of DC energy to the AC side.

[0099] Phase 2. During the positive half-cycle freewheeling phase of the grid voltage, the controller switches to turn on Q17 and Q18, and turns off the remaining transistors. Inductors L2 and L3 maintain continuous current due to current continuity. The path is: L2 → load → L3 → Q18 → Q17 → L2, ensuring continuous current.

[0100] Phase 3. During the negative half-cycle of the grid voltage, the controller turns on Q14 and Q15, while the remaining transistors turn off. The current path is: bus capacitor C3 → Q14 → inductor L3 → load → inductor L2 → Q15 → bus capacitor C3, completing the energy output during the negative half-cycle.

[0101] Phase 4. During the negative half-cycle freewheeling phase of the grid voltage, Q17 and Q18 remain on while the other transistors are off. The inductor freewheeling path is: L3 → load → L2 → Q17 → Q18 → L3, ensuring a smooth transition of the negative half-cycle current.

[0102] The transistors in the various embodiments of this application can be either MOSFETs or IGBTs, and are not limited thereto. When the transistor is a MOSFET, the input terminal of the transistor is the drain of the MOSFET, the output terminal of the transistor is the source of the MOSFET, and the control terminal of the transistor is the gate of the MOSFET. When the transistor is an IGBT, the input terminal of the transistor is the collector of the IGBT, the output terminal of the transistor is the emitter of the IGBT, and the control terminal of the transistor is the gate of the IGBT.

[0103] Corresponding to the above method embodiments, this application also provides a photovoltaic energy storage inverter control method. The photovoltaic energy storage inverter includes: a controller, a first battery access port, a second battery access port, a photovoltaic access port, a load access port, a mains power access port, a switching module, a first bidirectional DC-DC converter module, a second bidirectional DC-DC converter module, a bus capacitor, a DC-AC converter module, and an MPPT module. The switching module is connected to the low-voltage side of the first bidirectional DC-DC converter module, the high-voltage side of the second bidirectional DC-DC converter module, the first battery access port, and the second battery access port. The high-voltage side of the first bidirectional DC-DC converter module, the low-voltage side of the second bidirectional DC-DC converter module, the DC side of the DC-AC converter module, and the output side of the MPPT module are connected in parallel to the bus capacitor. The input side of the MPPT module is connected to the photovoltaic access port. The AC side of the DC-AC converter module is connected to the load access port and the mains power access port.

[0104] The method is applied to the controller, and the method includes:

[0105] Detect the access status of the first battery access port and the second battery access port;

[0106] When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0107] When it is detected that the second battery access port is connected to a low-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0108] When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0109] When it is detected that the second battery access port is connected to the high-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0110] When it is detected that both the first battery access port and the second battery access port are connected to the low-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the low-voltage side of the first bidirectional DC-DC converter module.

[0111] When it is detected that both the first battery access port and the second battery access port are connected to the high-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the high-voltage side of the second bidirectional DC-DC converter module;

[0112] When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port is connected to a high-voltage battery system, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module and the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module.

[0113] When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port is connected to a low-voltage battery system, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module and the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

[0114] The methods disclosed in the embodiments are described in a relatively simple manner since they correspond to the systems disclosed in the embodiments. For relevant details, please refer to the system section description.

[0115] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of this application. Therefore, the embodiments of this application are not to be limited to the embodiments shown herein, but are to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photovoltaic energy storage inverter, characterized in that, include: The system includes a controller, a first battery access port, a second battery access port, a photovoltaic access port, a load access port, a mains power access port, a switching module, a first bidirectional DC-DC converter module, a second bidirectional DC-DC converter module, a bus capacitor, a DC-AC converter module, and an MPPT module. The switching module is connected to the low-voltage side of the first bidirectional DC-DC converter module, the high-voltage side of the second bidirectional DC-DC converter module, the first battery access port, and the second battery access port. The high-voltage side of the first bidirectional DC-DC converter module, the low-voltage side of the second bidirectional DC-DC converter module, the DC side of the DC-AC converter module, and the output side of the MPPT module are connected in parallel to the bus capacitor. The input side of the MPPT module is connected to the photovoltaic access port; the AC side of the DC-AC conversion module is connected to the load access port and the mains power access port. The controller is used to detect the access status of the first battery access port and the second battery access port: When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module. When it is detected that the second battery access port is connected to a low-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module. When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module. When it is detected that the second battery access port is connected to the high-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module. When it is detected that both the first battery access port and the second battery access port are connected to the low-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the low-voltage side of the first bidirectional DC-DC converter module. When it is detected that both the first battery access port and the second battery access port are connected to the high-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the high-voltage side of the second bidirectional DC-DC converter module; When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port is connected to a high-voltage battery system, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module and the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module. When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port is connected to a low-voltage battery system, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module and the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

2. The photovoltaic energy storage inverter according to claim 1, characterized in that, The switching module includes: switch SW1, switch SW2, switch SW3, switch SW4, switch SW5, switch SW6, switch SW7 and switch SW8; One end of switch SW1 and one end of switch SW2 are both connected to the positive terminal of the first battery access port, one end of switch SW3 and one end of switch SW4 are both connected to the positive terminal of the second battery access port, one end of switch SW5 and one end of switch SW6 are both connected to the negative terminal of the second battery access port, and one end of switch SW7 and one end of switch SW8 are both connected to the negative terminal of the first battery access port. The other ends of switches SW1 and SW3 are both connected to the low-voltage positive terminal of the first bidirectional DC-DC converter module, the other ends of switches SW2 and SW4 are both connected to the high-voltage positive terminal of the second bidirectional DC-DC converter module, the other ends of switches SW5 and SW7 are both connected to the low-voltage negative terminal of the first bidirectional DC-DC converter module, and the other ends of switches SW6 and SW8 are both connected to the high-voltage negative terminal of the second bidirectional DC-DC converter module.

3. The photovoltaic energy storage inverter according to claim 1, characterized in that, The switches in the switching module are of the type of relay, contactor, or air switch.

4. The photovoltaic energy storage inverter according to claim 1, characterized in that, The first bidirectional DC-DC converter module is a bidirectional DC-DC converter module with electrical isolation function, and the second bidirectional DC-DC converter module is a full-bridge bidirectional Buck-Boost module.

5. The photovoltaic energy storage inverter according to claim 4, characterized in that, The first bidirectional DC-DC converter module includes: capacitor C1, transistor Q1, transistor Q2, transistor Q3, transistor Q4, transformer T1, resonant capacitor C2, transistor Q5, transistor Q6, transistor Q7, and transistor Q8. The high-voltage terminal of capacitor C1 is connected to the low-voltage positive terminal of the first bidirectional DC-DC converter module, the input terminal of transistor Q1, and the input terminal of transistor Q2. The low-voltage terminal of capacitor C1 is connected to the low-voltage side negative terminal of the first bidirectional DC-DC converter module, the output terminal of transistor Q3, and the output terminal of transistor Q4. The output terminal of transistor Q1, the input terminal of transistor Q3, and one end of the primary winding of transformer T1 are connected; the output terminal of transistor Q2, the input terminal of transistor Q4, and the other end of the primary winding of transformer T1 are connected. One end of the secondary winding of transformer T1 is connected to one end of resonant capacitor C2, and the other end of resonant capacitor C2 is connected to the output terminal of transistor Q5 and the input terminal of transistor Q7; the other end of the secondary winding of transformer T1 is connected to the output terminal of transistor Q6 and the input terminal of transistor Q8. The input terminals of transistors Q5 and Q6 are connected to the positive high-voltage side of the first bidirectional DC-DC converter module, and the output terminals of transistors Q7 and Q8 are connected to the negative high-voltage side of the first bidirectional DC-DC converter module.

6. The photovoltaic energy storage inverter according to claim 4, characterized in that, The second bidirectional DC-DC converter module includes: capacitor C4, transistor Q9, transistor Q10, inductor L1, transistor Q11, and transistor Q12; The high-voltage terminal of capacitor C4 is connected to the positive terminal of the high-voltage side of the second bidirectional DC-DC converter module and the input terminal of transistor Q9. The low-voltage terminal of capacitor C4 is connected to the negative terminal of the high-voltage side of the second bidirectional DC-DC converter module and the output terminal of transistor Q10. The output terminal of transistor Q9 is connected to the input terminal of transistor Q10 and one end of inductor L1. The other end of inductor L1 is connected to the input terminal of transistor Q11 and the output terminal of transistor Q12. The output terminal of transistor Q11 is connected to the output terminal of transistor Q10 and the negative terminal of the low-voltage side of the second bidirectional DC-DC converter module. The input terminal of transistor Q12 is connected to the positive terminal of the low-voltage side of the second bidirectional DC-DC converter module.

7. The photovoltaic energy storage inverter according to claim 1, characterized in that, The MPPT module is a Boost circuit; the Boost circuit includes capacitor C6, inductor L4, transistor Q19, diode D1 and capacitor C7; The high-voltage terminal of capacitor C6 is connected to one end of inductor L4 and the positive terminal of the input side of the Boost circuit. The other end of inductor L4 is connected to the input terminal of transistor Q19 and the anode of diode D1. The cathode of diode D1 is connected to the high-voltage terminal of capacitor C7. The low-voltage terminal of capacitor C6 is connected to the negative terminal of the input terminal of the Boost circuit, the negative terminal of the output terminal of the Boost circuit, the output terminal of transistor Q19, and the low-voltage terminal of capacitor C7.

8. The photovoltaic energy storage inverter according to claim 1, characterized in that, The DC-AC conversion module includes: transistor Q13, transistor Q14, transistor Q15, transistor Q16, transistor Q17, transistor Q18, inductor L2, inductor L3, and capacitor C5; The input terminals of transistors Q13 and Q14 are connected to the positive DC side of the DC-AC converter module. The output terminals of transistors Q15 and Q16 are connected to the negative DC side of the DC-AC converter module. The output terminal of transistor Q13, the input terminal of transistor Q15, the input terminal of transistor Q17, and one end of inductor L2 are connected. The output terminal of transistor Q14, the input terminal of transistor Q16, the input terminal of transistor Q18, and one end of inductor L3 are connected. The output terminal of transistor Q17 is connected to the output terminal of transistor Q18. The other end of inductor L2 is connected to one end of capacitor C5. The other end of inductor L3 is connected to the other end of capacitor C5. Capacitor C5 is connected to the AC power input port and the load input port.

9. The photovoltaic energy storage inverter according to any one of claims 5 to 8, characterized in that, The transistors in the photovoltaic energy storage inverter are either MOSFETs or IGBTs.

10. A control method for a photovoltaic energy storage inverter, characterized in that, The photovoltaic energy storage inverter includes: a controller, a first battery access port, a second battery access port, a photovoltaic access port, a load access port, a mains access port, a switching module, a first bidirectional DC-DC converter module, a second bidirectional DC-DC converter module, a bus capacitor, a DC-AC converter module, and an MPPT module; the switching module is connected to the low-voltage side of the first bidirectional DC-DC converter module, the high-voltage side of the second bidirectional DC-DC converter module, the first battery access port, and the second battery access port; the high-voltage side of the first bidirectional DC-DC converter module, the low-voltage side of the second bidirectional DC-DC converter module, the DC side of the DC-AC converter module, and the output side of the MPPT module are connected in parallel to the bus capacitor; the input side of the MPPT module is connected to the photovoltaic access port; the AC side of the DC-AC converter module is connected to the load access port and the mains access port; The method is applied to the controller, and the method includes: Detect the access status of the first battery access port and the second battery access port; When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module. When it is detected that the second battery access port is connected to a low-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module. When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port has no voltage input, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module. When it is detected that the second battery access port is connected to the high-voltage battery system and the first battery access port has no voltage input, the switching module is controlled to connect the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module. When it is detected that both the first battery access port and the second battery access port are connected to the low-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the low-voltage side of the first bidirectional DC-DC converter module. When it is detected that both the first battery access port and the second battery access port are connected to the high-voltage battery system, the switching module is controlled to connect the first battery access port and the second battery access port in parallel to the high-voltage side of the second bidirectional DC-DC converter module; When it is detected that the first battery access port is connected to a low-voltage battery system and the second battery access port is connected to a high-voltage battery system, the switching module is controlled to connect the first battery access port to the low-voltage side of the first bidirectional DC-DC converter module and the second battery access port to the high-voltage side of the second bidirectional DC-DC converter module. When it is detected that the first battery access port is connected to a high-voltage battery system and the second battery access port is connected to a low-voltage battery system, the switching module is controlled to connect the first battery access port to the high-voltage side of the second bidirectional DC-DC converter module and the second battery access port to the low-voltage side of the first bidirectional DC-DC converter module.

Images