Optical storage system, bidirectional DC-DC converter and power converter

Abstract

The application relates to a light storage system which comprises a step-down conversion circuit, a step-up conversion circuit and a bidirectional inversion circuit; an input end of the step-down conversion circuit is used for connecting a photovoltaic power supply, an input end of the step-up conversion circuit is used for connecting an energy storage battery; and an output end of the step-down conversion circuit and an output end of the step-up conversion circuit are connected in parallel to a direct current end of the bidirectional inversion circuit. Accordingly, the working reliability of the light storage system is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a photovoltaic energy storage system, a bidirectional DC-DC converter, and a power converter. Background Technology

[0002] A photovoltaic (PV) energy storage system, also known as a solar photovoltaic energy storage power generation system, is a power generation system composed of photovoltaic (PV) equipment and energy storage equipment. However, under the current topology of PV-energy storage systems in related technologies, the operational reliability of these systems is not ideal. Utility Model Content

[0003] Therefore, it is necessary to provide a photovoltaic energy storage system, a bidirectional DC-DC converter, and a power converter that can improve the operational reliability of the photovoltaic energy storage system.

[0004] In a first aspect, embodiments of this application provide a photovoltaic energy storage system, which includes a buck converter circuit, a boost converter circuit, and a bidirectional inverter circuit;

[0005] The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery.

[0006] The output terminal of the buck converter circuit and the output terminal of the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

[0007] In one embodiment, the output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to a DC bus, and the DC bus is connected to the DC terminal of the bidirectional inverter circuit; wherein, during the operation of the photovoltaic energy storage system, the voltage of the DC bus is less than the voltage of the photovoltaic power supply.

[0008] In one embodiment, the photovoltaic-storage system further includes a photovoltaic power source and an energy storage battery;

[0009] Each of the photovoltaic power sources is connected to the input terminal of a buck converter circuit, and each of the energy storage batteries is connected to the input terminal of a boost converter circuit.

[0010] In one embodiment, the energy storage battery is a small-capacity battery; the small-capacity battery is a battery with a storage capacity less than a preset number of kilowatt-hours.

[0011] In one embodiment, the preset degree is 10 kWh.

[0012] In one embodiment, the buck converter circuit includes a first power switch module and a first energy storage module;

[0013] The first terminal of the first power switch module is connected to the first electrode of the photovoltaic power supply;

[0014] The second terminal of the first power switch module is connected to the second electrode of the photovoltaic power supply, and the second terminal of the first power switch module is connected to the second electrode of the DC terminal of the bidirectional inverter circuit;

[0015] The third terminal of the first power switch module is connected to the first terminal of the first energy storage module, and the second terminal of the first energy storage module is connected to the first pole of the DC terminal of the bidirectional inverter circuit.

[0016] In one embodiment, the boost converter circuit includes a second power switch module and a second energy storage module;

[0017] The first end of the second energy storage module is connected to the first electrode of the energy storage battery;

[0018] The first terminal of the second power switch module is connected to the second terminal of the second energy storage module;

[0019] The second terminal of the second power switch module is connected to the second terminal of the energy storage battery, and the second terminal of the second power switch module is connected to the second terminal of the DC terminal of the bidirectional inverter circuit;

[0020] The third terminal of the second power switch module is connected to the first terminal of the DC terminal of the bidirectional inverter circuit.

[0021] In one embodiment, the optical storage system further includes an anti-reverse flow circuit;

[0022] The anti-backflow circuit is located between the input terminal of the buck converter circuit and the photovoltaic power supply. The anti-backflow circuit is used to prevent current signals from flowing back into the photovoltaic power supply from the buck converter circuit.

[0023] In one embodiment, the optical storage system further includes a pre-charge and bidirectional switching circuit;

[0024] The precharge and bidirectional switching circuit is located between the input terminal of the boost converter circuit and the energy storage battery.

[0025] Secondly, based on the same inventive concept as the first aspect, embodiments of this application provide a power converter, which includes a bidirectional DC-DC converter circuit and a bidirectional inverter circuit;

[0026] The bidirectional DC-DC converter circuit includes a buck converter circuit and a boost converter circuit;

[0027] The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery.

[0028] The output terminal of the buck converter circuit and the output terminal of the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

[0029] Thirdly, based on the same inventive concept as the first aspect, embodiments of this application provide a bidirectional DC-DC converter, which includes a buck converter circuit and a boost converter circuit;

[0030] The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery.

[0031] The output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

[0032] Fourthly, based on the same inventive concept as the first aspect, embodiments of this application provide a photovoltaic energy storage system, which includes a bidirectional DC-DC converter and a bidirectional micro-inverter;

[0033] The bidirectional DC-DC converter includes a buck converter circuit and a boost converter circuit;

[0034] The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery.

[0035] The output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to the DC terminal of the bidirectional microinverter.

[0036] In one embodiment, the bidirectional DC-DC converter further includes a first controller;

[0037] The bidirectional microinverter includes a second controller;

[0038] The second controller is communicatively connected to the first controller, and the second controller is used to send control signals to the first controller;

[0039] The first controller is connected to the buck converter circuit and the boost converter circuit respectively. The first controller is used to send corresponding drive signals to the buck converter circuit and the boost converter circuit according to the control signal, wherein the drive signals are used to drive the buck converter circuit and the boost converter circuit.

[0040] The aforementioned photovoltaic-storage system, bidirectional DC-DC converter, and power converter, by setting the input terminal of the buck converter circuit to connect to the photovoltaic power source, the input terminal of the boost converter circuit to connect to the energy storage battery, and the output terminals of the buck converter circuit and the boost converter circuit connected in parallel to the DC terminal of the bidirectional inverter circuit, ensure that in the photovoltaic-storage system of this application embodiment, the voltage output from the energy storage battery to the DC terminal of the bidirectional inverter circuit is boosted, while the voltage output from the photovoltaic power source to the DC terminal of the bidirectional inverter circuit is stepped down. This prevents the voltage difference between the minimum effective voltage of the energy storage battery and the voltage at the DC terminal of the bidirectional inverter circuit from becoming too large. This ensures that even when the energy storage battery is at its minimum effective voltage, it can still reliably connect to the DC terminal of the bidirectional inverter circuit, thereby improving the operational reliability of the energy storage battery and consequently, the operational reliability of the photovoltaic-storage system.

[0041] Furthermore, compared to the voltage being boosted at the DC end of the photovoltaic power supply to the bidirectional inverter circuit, in the photovoltaic-storage system of this application embodiment, the voltage being stepped down at the DC end of the bidirectional inverter circuit ensures that the DC end voltage of the bidirectional inverter circuit is not too high, but rather in a lower state. Thus, the DC-side structures of the buck converter circuit, boost converter circuit, and bidirectional inverter circuit in the photovoltaic-storage system can all use lower-power devices. Compared to the DC-side structures of the buck converter circuit, boost converter circuit, and bidirectional inverter circuit using higher-power devices, the embodiments of this application reduce the cost of the buck converter circuit, boost converter circuit, and bidirectional inverter circuit, thereby reducing the cost of the photovoltaic-storage system. Moreover, compared to the voltage being boosted at the DC end of the photovoltaic power supply to the bidirectional inverter circuit, the voltage being stepped down at the DC end of the bidirectional inverter circuit in this application embodiment results in higher operating efficiency and better performance for the photovoltaic-storage system. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is one of the schematic diagrams of the topology of a photovoltaic energy storage system according to an embodiment;

[0044] Figure 2 This is a second schematic diagram of the topology of an embodiment of a photovoltaic energy storage system;

[0045] Figure 3 This is the third schematic diagram of the topology of an embodiment of a photovoltaic energy storage system;

[0046] Figure 4 This is one of the schematic diagrams of a buck converter circuit according to an embodiment;

[0047] Figure 5 This is a second schematic diagram of the buck converter circuit in one embodiment;

[0048] Figure 6 This is one of the schematic diagrams of a boost converter circuit according to an embodiment;

[0049] Figure 7 This is a second schematic diagram of a boost converter circuit according to one embodiment;

[0050] Figure 8 This is the fourth schematic diagram of the topology of an embodiment of a photovoltaic energy storage system;

[0051] Figure 9 This is the fifth schematic diagram of the topology of an embodiment of a photovoltaic energy storage system;

[0052] Figure 10 This is the sixth schematic diagram of the topology of an embodiment of a photovoltaic energy storage system;

[0053] Figure 11 This is a schematic diagram of the precharge and bidirectional switching circuit of one embodiment;

[0054] Figure 12 This is a schematic diagram of the topology of a power converter according to one embodiment;

[0055] Figure 13 This is a schematic diagram of the topology of a bidirectional DC-DC converter according to an embodiment;

[0056] Figure 14 This is the seventh schematic diagram of the topology of an embodiment of a photovoltaic energy storage system;

[0057] Figure 15 This is the eighth schematic diagram of the topology of an embodiment of a photovoltaic energy storage system.

[0058] Explanation of reference numerals in the attached diagram: 10-Step-down converter circuit, 20-Step-up converter circuit, 30-Bidirectional inverter circuit, 40-DC bus, 50-Photovoltaic power supply, 60-Energy storage battery, 70-Anti-reverse current circuit, 80-Pre-charge and bidirectional switching circuit, 101-First power switch module, 102-First energy storage module, 103-First filter module, 104-Second filter module, 201-Second power switch module, 202-Second energy storage module, 203-Third filter module, 204-Fourth filter module, 205-Current limiting module. Detailed Implementation

[0059] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0061] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0062] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0063] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0064] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0065] In one exemplary embodiment, reference is made to Figure 1 A photovoltaic energy storage system is provided, which includes a buck converter circuit 10, a boost converter circuit 20, and a bidirectional inverter circuit 30.

[0066] The input terminal of the buck converter circuit 10 is used to connect to the photovoltaic power supply 50, the input terminal of the boost converter circuit 20 is used to connect to the energy storage battery 60, the output terminal of the buck converter circuit 10 and the output terminal of the boost converter circuit 20 are connected in parallel to the DC terminal of the bidirectional inverter circuit 30, and the AC terminal of the bidirectional inverter circuit 30 is used to connect to the power grid.

[0067] This can be achieved by having at least one buck converter circuit 10 corresponding to one bidirectional inverter circuit 30, and at least one boost converter circuit 20 corresponding to one bidirectional inverter circuit 30. The bidirectional inverter circuit 30 can convert DC to AC or AC to DC.

[0068] The buck converter circuit 10 is capable of stepping down the output voltage of the connected photovoltaic power source 50. The buck converter circuit 10 receives the output voltage of the connected photovoltaic power source 50, steps down the received output voltage, and outputs the stepped-down voltage to the DC terminal of the bidirectional inverter circuit 30. The buck converter circuit 10 is, for example, a Buck circuit. The photovoltaic power source 50 may include at least one photovoltaic module; if multiple photovoltaic modules are provided, the multiple photovoltaic modules are connected in series, for example, but not limited to. The photovoltaic module may include at least one solar panel; if multiple solar panels are provided, the multiple solar panels are connected in series, for example, but not limited to. For example, the output voltage of the photovoltaic power source 50 is approximately 50V, which is stepped down to approximately 30V after passing through the buck converter circuit 10, and this approximately 30V voltage is output to the DC terminal of the bidirectional inverter circuit 30.

[0069] The boost converter circuit 20 is capable of boosting the output voltage of the connected energy storage battery 60. The boost converter circuit 20 receives the output voltage of the connected energy storage battery 60, boosts the received output voltage, and outputs the boosted voltage to the DC terminal of the bidirectional inverter circuit 30. The boost converter circuit 20 is, for example, a Boost circuit. The energy storage battery 60 may include at least one energy storage battery 60; when multiple energy storage batteries 60 are provided, the multiple energy storage batteries 60 are connected in series, for example, but not limited to. For example, when the energy storage battery 60 has a very low charge, the lowest effective voltage output by the energy storage battery 60 is about 3V to 6V. After passing through the boost converter circuit 20, it is boosted to about 30V, and this voltage of about 30V is output to the DC terminal of the bidirectional inverter circuit 30. As another example, when the energy storage battery 60 has a high charge, the effective voltage output by the energy storage battery 60 is about 20V. After passing through the boost converter circuit 20, it is boosted to about 30V, and this voltage of about 30V is output to the DC terminal of the bidirectional inverter circuit 30.

[0070] Understandably, in related technologies, the output voltage of the photovoltaic power supply 50 is approximately 50V. The voltage output from the photovoltaic power supply 50 to the DC terminal of the bidirectional inverter circuit 30 is boosted to approximately 70V. This approximately 70V voltage is then output to the DC terminal of the bidirectional inverter circuit 30. Since the output terminal of the boost converter circuit 20 connected to the photovoltaic power supply 50 is connected in parallel to the output terminal of the boost converter circuit 20 of the energy storage battery 60 to the DC terminal of the bidirectional inverter circuit 30, firstly, when the energy storage battery 60 is in its lowest effective voltage state, with an output lowest effective voltage of approximately 3V~6V, the boost converter circuit 20 used to connect the energy storage battery 60 needs to boost the voltage of approximately 3V~6V to approximately 70V. However, the voltage difference between 3V and 70V is too large, making it virtually impossible to boost from 3V to 70V. This results in the energy storage battery 60 being unable to reliably connect to the DC terminal of the bidirectional inverter circuit 30, thereby reducing the operational reliability of the photovoltaic-energy storage system.

[0071] Secondly, since the boost converter circuit 20 needs to boost the voltage from approximately 3V to 6V to approximately 70V, the boost converter circuit 20 itself needs to use high-power devices, which makes the cost of the boost converter circuit 20 high. Correspondingly, the boost converter circuit 20 connected to the photovoltaic power source 50 also needs to use high-power devices. Therefore, the cost of both the boost converter circuit 20 used to connect to the energy storage battery 60 and the boost converter circuit 20 used to connect to the photovoltaic power source 50 is high, which in turn leads to a high cost of the photovoltaic-energy storage system.

[0072] Finally: Since the output voltages of both the photovoltaic power source 50 and the energy storage battery 60 are boosted, the boosted high voltage is output to the DC terminal of the bidirectional inverter circuit 30. This requires the use of high-power devices on the DC side of the bidirectional inverter circuit 30, resulting in higher costs for the bidirectional inverter circuit 30 and further increasing the cost of the photovoltaic-energy storage system. Also, since the output voltage of the photovoltaic power source 50 is boosted, the boosting process is less efficient than the bucking process, resulting in lower efficiency for the photovoltaic-energy storage system.

[0073] In view of this, the photovoltaic-storage system provided in this application embodiment, by setting the input terminal of the buck converter circuit 10 to connect to the photovoltaic power supply 50, the input terminal of the boost converter circuit 20 to connect to the energy storage battery 60, and the output terminals of the buck converter circuit 10 and the boost converter circuit 20 connected in parallel to the DC terminal of the bidirectional inverter circuit 30, ensures that in the photovoltaic-storage system of this application embodiment, the voltage output from the energy storage battery 60 to the DC terminal of the bidirectional inverter circuit 30 is boosted, while at the same time, the voltage output from the photovoltaic power supply 50 to the DC terminal of the bidirectional inverter circuit 30 is stepped down. Thus, the voltage difference between the minimum effective voltage of the energy storage battery 60 and the voltage at the DC terminal of the bidirectional inverter circuit 30 will not be too large, for example, a reasonable voltage difference between 3V and 30V. This ensures that even if the energy storage battery 60 is in the minimum effective voltage state, the energy storage battery 60 can still be reliably connected to the DC terminal of the bidirectional inverter circuit 30, thereby improving the working reliability of the energy storage battery 60 and thus improving the working reliability of the photovoltaic-storage system.

[0074] Furthermore, compared to the voltage being boosted at the DC terminal of the photovoltaic power source 50 to the bidirectional inverter circuit 30, in the photovoltaic energy storage system of this application embodiment, the voltage being stepped down at the DC terminal of the bidirectional inverter circuit 30 ensures that the DC terminal voltage of the bidirectional inverter circuit 30 is not too high, but rather at a lower level, for example, approximately 30V. Thus, the DC-side structures of the buck converter circuit 10, the boost converter circuit 20, and the bidirectional inverter circuit 30 in the photovoltaic energy storage system can all utilize lower-power devices, compared to using higher-power devices. Compared to the DC-side structure of the buck converter circuit 10, boost converter circuit 20, and bidirectional inverter circuit 30, the embodiments of this application reduce the cost of the buck converter circuit 10, boost converter circuit 20, and bidirectional inverter circuit 30, thereby reducing the cost of the photovoltaic energy storage system. Furthermore, compared to the voltage being boosted when the photovoltaic power supply 50 outputs to the DC terminal of the bidirectional inverter circuit 30, the embodiments of this application reduce the voltage being bucked when the photovoltaic power supply 50 outputs to the DC terminal of the bidirectional inverter circuit 30, which can make the photovoltaic energy storage system more efficient and have better performance.

[0075] In one exemplary embodiment, reference is made to Figure 2 The output terminals of the buck converter circuit 10 and the boost converter circuit 20 are connected in parallel to the DC bus 40, and the DC bus 40 is connected to the DC terminal of the bidirectional inverter circuit 30. During the operation of the photovoltaic energy storage system, the voltage of the DC bus is less than the voltage of the photovoltaic power supply 50.

[0076] In this embodiment, the voltage of the DC bus 40 is the voltage of the photovoltaic power supply 50 after being stepped down by the buck converter circuit 10. The voltage of the DC bus 40 is lower than the voltage of the photovoltaic power supply 50, which ensures that the voltage difference between the minimum effective voltage of the energy storage battery 60 and the voltage of the DC bus 40 will not be too large. This ensures that even if the energy storage battery 60 is in the minimum effective voltage state, the energy storage battery 60 can still be reliably connected to the DC bus 40, thereby improving the working reliability of the energy storage battery 60 and thus improving the working reliability of the photovoltaic-energy storage system. At the same time, since the voltage of the DC bus 40 is in a low state, the DC side structure of the buck converter circuit 10, the boost converter circuit 20, and the bidirectional inverter circuit 30 in the photovoltaic-energy storage system can all use low-power devices, reducing the cost of the photovoltaic-energy storage system.

[0077] In one exemplary embodiment, reference is made to Figure 3 The photovoltaic-storage system also includes at least one photovoltaic power source 50 and at least one energy storage battery 60, wherein each photovoltaic power source 50 is connected to the input terminal of a buck converter circuit 10, and each energy storage battery 60 is connected to the input terminal of a boost converter circuit 20. It should be noted that... Figure 3 In the diagram, photovoltaic power supply 50 is represented by photovoltaic DC power supply, and energy storage battery power supply 60 is represented by energy storage battery power supply.

[0078] In this embodiment, the voltage output from each energy storage battery 60 to the DC terminal of the bidirectional inverter circuit 30 is boosted, while the voltage output from each photovoltaic power source 50 to the DC terminal of the bidirectional inverter circuit 30 is stepped down. This ensures that the voltage difference between the lowest effective voltage of each energy storage battery 60 and the voltage at the DC terminal of the bidirectional inverter circuit 30 is not excessive. This guarantees that even if any energy storage battery 60 is at its lowest effective voltage, it can still reliably connect to the DC terminal of the bidirectional inverter circuit 30, thereby improving the operational reliability of the energy storage batteries 60 in the photovoltaic-energy storage system, and consequently, the overall operational reliability of the photovoltaic-energy storage system. Furthermore, the DC-side structure of the buck converter circuit 10, the boost converter circuit 20, and the bidirectional inverter circuit 30 in the photovoltaic-energy storage system can utilize low-power devices, reducing the cost of the photovoltaic-energy storage system. Additionally, stepping down the voltage output from the photovoltaic power source 50 to the DC terminal of the bidirectional inverter circuit 30 allows for higher operational efficiency and better performance of the photovoltaic-energy storage system.

[0079] In one exemplary embodiment, the energy storage battery 60 is a small-capacity battery, which is a battery with a storage capacity less than a preset number of kilowatt-hours.

[0080] Optionally, the preset capacity is 10 kWh. Since the voltage output from the photovoltaic power source 50 to the DC terminal of the bidirectional inverter circuit 30 is stepped down, even if the storage capacity of the energy storage battery 60 is less than 10 kWh, the voltage difference between the minimum effective voltage of the energy storage battery 60 and the voltage at the DC terminal of the bidirectional inverter circuit 30 will not be too large. Even when the energy storage battery 60 is at its minimum effective voltage, it can still be reliably connected to the DC terminal of the bidirectional inverter circuit 30. Furthermore, the storage capacity of the energy storage battery 60 being less than 10 kWh is beneficial for realizing residential photovoltaic-energy storage systems or other small and medium-sized photovoltaic-energy storage systems, meeting users' needs for highly reliable, efficient, and low-cost residential photovoltaic-energy storage systems.

[0081] In one exemplary embodiment, reference is made to Figure 4 The step-down converter circuit 10 includes a first power switch module 101 and a first energy storage module 102. The first terminal of the first power switch module 101 is connected to the first electrode of the photovoltaic power supply 50, and the second terminal of the first power switch module 101 is connected to the second electrode of the photovoltaic power supply 50, and also connected to the second electrode of the DC terminal of the bidirectional inverter circuit 30. The third terminal of the first power switch module 101 is connected to the first terminal of the first energy storage module 102, and the second terminal of the first energy storage module 102 is connected to the first electrode of the DC terminal of the bidirectional inverter circuit 30. Optionally, refer to [reference needed]. Figure 4 The step-down converter circuit 10 may further include a first filter module 103 and a second filter module 104; the first end of the first filter module 103 is connected to the first end of the first power switch module 101, and the second end of the first filter module 103 is connected to the second end of the first power switch module 101; the first end of the second filter module 104 is connected to the third end of the first power switch module 101, and the second end of the second filter module 104 is connected to the second end of the first power switch module 101.

[0082] The first power switch module 101 has functions such as controlling on / off switching, regulating voltage, controlling inductor current, regulating power transmission, reducing losses, and realizing soft switching.

[0083] The first energy storage module 102 has functions such as converting electrical energy to magnetic energy, maintaining energy transfer, limiting the rate of change of current, regulating the average current, smoothing current ripple, and auxiliary filtering.

[0084] The first filter module 103 and the second filter module 104 have functions such as smoothing the output voltage, filtering out high-frequency noise, assisting energy transmission, maintaining the output voltage, regulating the voltage, and improving the load response.

[0085] In an exemplary embodiment, the first power switching module 101 includes a first switching transistor unit and a second switching transistor unit, the first filtering module 103 includes a first capacitor unit, the second filtering module 104 includes a second capacitor unit, and the first energy storage module 102 includes a first inductor unit.

[0086] The first end of the first capacitor unit is connected to the first electrode of the photovoltaic power supply 50, and the second end of the first capacitor unit is connected to the second electrode of the photovoltaic power supply 50; the first end of the first switching transistor unit is connected to the first end of the first capacitor unit, and the second end of the first switching transistor unit is connected to the first end of the first inductor unit, and the second end of the first inductor unit is connected to the first electrode of the DC terminal of the bidirectional inverter circuit 30; the first end of the second switching transistor unit is connected to the second end of the first switching transistor unit, and the second end of the second switching transistor unit is connected to the second end of the first capacitor unit; the first end of the second capacitor unit is connected to the second end of the first inductor unit, the second end of the second capacitor unit is connected to the second end of the second switching transistor unit, and the second end of the second capacitor unit is connected to the second electrode of the DC terminal of the bidirectional inverter circuit 30.

[0087] The first switching transistor unit may include at least one switching transistor, the second switching transistor unit may include at least one switching transistor, the first capacitor unit may include at least one capacitor, the second capacitor unit may include at least one capacitor, and the first inductor unit may include at least one inductor. For example, see reference... Figure 5 The first switching transistor unit includes a first switching transistor M1, the second switching transistor unit includes a second switching transistor M2, the first capacitor unit includes a first capacitor C1, the second capacitor unit includes a second capacitor C2, and the first inductor unit includes a first inductor L1. In this way, the buck converter circuit 10 has a simple structure, low cost, is easy to implement, and is highly practical.

[0088] In one exemplary embodiment, reference is made to Figure 6 The boost converter circuit 20 includes a second power switch module 201 and a second energy storage module 202; the first terminal of the second energy storage module 202 is connected to the first terminal of the energy storage battery 60; the first terminal of the second power switch module 201 is connected to the second terminal of the second energy storage module 202; the second terminal of the second power switch module 201 is connected to the second terminal of the energy storage battery 60, and the second terminal of the second power switch module 201 is connected to the second terminal of the DC terminal of the bidirectional inverter circuit 30; the third terminal of the second power switch module 201 is connected to the first terminal of the DC terminal of the bidirectional inverter circuit 30. Optionally, refer to [reference needed]. Figure 6The boost converter circuit 20 may also include a third filter module 203, a fourth filter module 204, and a current limiting module 205; the first end of the third filter module 203 is connected to the first end of the second energy storage module 202 through the current limiting module 205, the second end of the third filter module 203 is connected to the second end of the second power switch module 201, the first end of the fourth filter module 204 is connected to the third end of the second power switch module 201, and the second end of the fourth filter module 204 is connected to the second end of the second power switch module 201.

[0089] The second power switch module 201 has functions such as storing energy, releasing energy, changing the duty cycle to boost voltage, boosting voltage with high-frequency switching action, reducing conduction loss, and controlling switching loss.

[0090] The second energy storage module 202 has functions such as electrical energy to magnetic energy conversion, maintaining energy supply, generating back electromotive force, smoothing current ripple, and auxiliary filtering.

[0091] The current limiting module 205 has functions such as current sampling, voltage sampling, biasing, current limiting, consuming excess energy, heat dissipation, oscillation suppression, and prevention of parasitic oscillation.

[0092] The third filter module 203 and the fourth filter module 204 have functions such as energy replenishment, output maintenance, output smoothing, high-frequency bypass, voltage regulation, and response improvement.

[0093] In one exemplary embodiment, the second power switch module 201 includes a third switch unit and a fourth switch unit, the third filter module 203 includes a third capacitor unit, the fourth filter module 204 includes a fourth capacitor unit, the second energy storage module 202 includes a second inductor unit, and the current limiting module 205 includes a first resistor unit.

[0094] The first terminal of the third capacitor unit is connected to the first terminal of the energy storage battery 60, and the second terminal of the third capacitor unit is connected to the second terminal of the energy storage battery 60; the first terminal of the first resistor unit is connected to the first terminal of the third capacitor unit, the second terminal of the first resistor unit is connected to the first terminal of the second inductor unit, the second terminal of the second inductor unit is connected to the first terminal of the third switching transistor unit, the second terminal of the third switching transistor unit is connected to the first terminal of the fourth capacitor unit, the first terminal of the fourth capacitor unit is connected to the first terminal of the DC terminal of the bidirectional inverter circuit 30, and the second terminal of the fourth capacitor unit is connected to the second terminal of the DC terminal of the bidirectional inverter circuit 30; the first terminal of the fourth switching transistor unit is connected to the first terminal of the third switching transistor unit, the second terminal of the fourth switching transistor unit is connected to the second terminal of the third capacitor unit, and the second terminal of the fourth switching transistor unit is connected to the second terminal of the fourth capacitor unit.

[0095] The third switching unit may include at least one switching transistor, the fourth switching unit may include at least one switching transistor, the third capacitor unit may include at least one capacitor, the fourth capacitor unit may include at least one capacitor, the second inductor unit may include at least one inductor, and the first resistor unit may include at least one resistor. For example, refer to... Figure 7 The third switching transistor unit includes a third switching transistor M3, the fourth switching transistor unit includes a fourth switching transistor M4, the third capacitor unit includes a third capacitor C3, the fourth capacitor unit includes a fourth capacitor C4, the second inductor unit includes a second inductor L2, and the first resistor unit includes a first resistor R1. In this way, the boost converter circuit 20 has a simple structure, low cost, is easy to implement, and is highly practical.

[0096] In one exemplary embodiment, reference is made to Figure 8 The photovoltaic energy storage system may also include a backflow prevention circuit 70; the backflow prevention circuit 70 is located between the input terminal of the step-down converter circuit 10 and the photovoltaic power supply 50, and the backflow prevention circuit 70 is used to prevent current signals from flowing back into the photovoltaic power supply 50 from the step-down converter circuit 10.

[0097] In this circuit, a reverse current protection circuit 70 is provided between each photovoltaic power source 50 and the input terminal of the corresponding buck converter circuit 10. The reverse current protection circuit 70 is used to prevent current from flowing back into the photovoltaic power source 50. The reverse current protection circuit 70 may include at least one switching transistor. For example, refer to... Figure 9 The anti-backflow circuit 70 includes an eighth switch M8, which is connected between the second terminal of the photovoltaic power supply 50 and the second terminal of the first capacitor C1. This makes the anti-backflow circuit 70 simple in structure, low in cost, and easy to implement.

[0098] In one exemplary embodiment, reference is made to Figure 10 The photovoltaic energy storage system may also include a pre-charge and bidirectional switching circuit 80; the pre-charge and bidirectional switching circuit 80 is located between the input terminal of the boost converter circuit 20 and the energy storage battery 60.

[0099] Each energy storage battery 60 is connected to the input terminal of its corresponding boost converter circuit 20 via a pre-charge and bidirectional switching circuit 80. The pre-charge and bidirectional switching circuit 80 has both pre-charge and switching functions. For example, the pre-charge and bidirectional switching circuit 80 includes a fifth switching transistor unit, a sixth switching transistor unit, a seventh switching transistor unit, a fifth capacitor unit, and a second resistor unit.

[0100] The first terminal of the fifth switching transistor unit is connected to the first terminal of the energy storage battery 60, the second terminal of the fifth switching transistor unit is connected to the first terminal of the sixth switching transistor unit, and the second terminal of the sixth switching transistor unit is connected to the first terminal of the input terminal of the boost converter circuit 20; the first terminal of the seventh switching transistor unit is connected to the first terminal of the sixth switching transistor unit, the second terminal of the seventh switching transistor unit is connected to the first terminal of the second resistor unit, and the first terminal of the second resistor unit is connected to the second terminal of the sixth switching transistor unit; the first terminal of the fifth capacitor unit is connected to the second terminal of the sixth switching transistor unit, the second terminal of the fifth capacitor unit is connected to the second terminal of the energy storage battery 60, and the second terminal of the fifth capacitor unit is connected to the second terminal of the input terminal of the boost converter circuit 20.

[0101] The fifth switching unit may include at least one switching transistor, the sixth switching unit may include at least one switching transistor, the seventh switching unit may include at least one switching transistor, the fifth capacitor unit may include at least one capacitor, and the second resistor unit may include at least one resistor. For example, refer to... Figure 11 The fifth switching transistor unit includes a fifth switching transistor M5, the sixth switching transistor unit includes a sixth switching transistor M6, the seventh switching transistor unit includes a seventh switching transistor M7, the fifth capacitor unit includes a fifth capacitor C5, and the second resistor unit includes a second resistor R2. This makes the precharge and bidirectional switching circuit 80 simple in structure, low in cost, and easy to implement.

[0102] In addition, a fuse can be installed between the first terminal of the energy storage battery 60 and the fifth switching transistor M5, and a sampling resistor can be installed between the second terminal of the fifth capacitor and the second terminal of the energy storage battery 60.

[0103] In one exemplary embodiment, reference is made to Figure 12 This application also provides a power converter, which includes a bidirectional DC-DC converter circuit and a bidirectional inverter circuit; the bidirectional DC-DC converter circuit includes a buck converter circuit and a boost converter circuit; the input terminal of the buck converter circuit is used to connect to a photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to an energy storage battery; the output terminal of the buck converter circuit and the output terminal of the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

[0104] The power converter provided in this application embodiment and the photovoltaic energy storage system provided in any of the above embodiments belong to the same utility model concept, can solve the same technical problems, and thus achieve the same technical effects. Repeated content will not be repeated here.

[0105] In one exemplary embodiment, reference is made to Figure 13This application also provides a bidirectional DC-DC converter (BDC), which includes a buck converter circuit 10 and a boost converter circuit 20. The input terminal of the buck converter circuit 10 is used to connect to a photovoltaic power source 50, and the input terminal of the boost converter circuit 20 is used to connect to an energy storage battery 60. The output terminals of the buck converter circuit 10 and the boost converter circuit 20 are connected in parallel to the DC terminal of the bidirectional inverter circuit 30.

[0106] The bidirectional DC-DC converter provided in this application and the optical storage system provided in any of the above embodiments belong to the same utility model concept, can solve the same technical problems, and thus achieve the same technical effects. Repeated content will not be repeated here.

[0107] In one exemplary embodiment, reference is made to Figure 14 This application also provides a photovoltaic-storage system, which includes a bidirectional DC-DC converter and a bidirectional micro-inverter. The bidirectional DC-DC converter includes a buck converter circuit and a boost converter circuit. The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery. The output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to the DC terminal of the bidirectional micro-inverter.

[0108] The optical storage system provided in this embodiment and the optical storage system provided in any of the above embodiments belong to the same utility model concept, can solve the same technical problems, and thus achieve the same technical effects. Repeated content will not be repeated here.

[0109] The buck converter circuit 10, the boost converter circuit 20, and the DC-side structure of the bidirectional microinverter can all utilize lower-power devices, reducing the cost of the photovoltaic-storage system. The bidirectional microinverter can convert both DC to AC and AC to DC. The inclusion of a bidirectional microinverter facilitates the development of residential photovoltaic-storage systems or other small- to medium-sized systems, meeting users' demands for high reliability, high efficiency, and low cost in residential photovoltaic-storage systems. Typically, the bidirectional microinverter itself requires a relatively low input voltage; therefore, the step-down voltage of the photovoltaic power supply 50 is well-suited to the voltage required by the bidirectional microinverter, allowing the use of lower-power devices on the DC-side structure of the bidirectional microinverter. This reduces the cost of the bidirectional microinverter and consequently, the cost of the photovoltaic-storage system.

[0110] In one exemplary embodiment, reference is made to Figure 15The bidirectional DC-DC converter further includes a first controller (the first controller includes, for example, but not limited to, a first digital signal processing (DSP) circuit); the bidirectional micro-inverter includes a second controller (the second controller includes, for example, but not limited to, a second digital signal processing (DSP) circuit); the second controller is communicatively connected to the first controller, and the second controller is used to send control signals to the first controller; the first controller is connected to the buck converter 10 and the boost converter 20 respectively, and the first controller is used to send corresponding drive signals to the buck converter 10 and the boost converter 20 according to the control signals, wherein the drive signals are used to drive the buck converter 10 and the boost converter 20, and the first controller and the second controller can communicate with each other via a CAN bus.

[0111] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0112] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0113] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A photovoltaic energy storage system, characterized in that, The photovoltaic energy storage system includes a buck converter circuit, a boost converter circuit, and a bidirectional inverter circuit. The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery. The output terminal of the buck converter circuit and the output terminal of the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

2. The photovoltaic energy storage system according to claim 1, characterized in that, The output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to the DC bus, and are connected to the DC terminal of the bidirectional inverter circuit through the DC bus; wherein, during the operation of the photovoltaic energy storage system, the voltage of the DC bus is less than the voltage of the photovoltaic power supply.

3. The photovoltaic energy storage system according to claim 1, characterized in that, The photovoltaic-storage system also includes a photovoltaic power source and an energy storage battery; Each of the photovoltaic power sources is connected to the input terminal of a buck converter circuit, and each of the energy storage batteries is connected to the input terminal of a boost converter circuit.

4. The photovoltaic energy storage system according to claim 3, characterized in that, The energy storage battery is a small-capacity battery; the small-capacity battery is a battery with a storage capacity less than a preset number of kilowatt-hours.

5. The photovoltaic storage system according to claim 3 or 4, characterized in that, The photovoltaic energy storage system also includes a reverse-feedback circuit; The anti-backflow circuit is located between the input terminal of the buck converter circuit and the photovoltaic power supply. The anti-backflow circuit is used to prevent current signals from flowing back into the photovoltaic power supply from the buck converter circuit.

6. The photovoltaic storage system according to claim 3 or 4, characterized in that, The photovoltaic energy storage system also includes a pre-charging and bidirectional switching circuit; The precharge and bidirectional switching circuit is located between the input terminal of the boost converter circuit and the energy storage battery.

7. A power converter, characterized in that, The power converter includes a bidirectional DC-DC converter circuit and a bidirectional inverter circuit; The bidirectional DC-DC converter circuit includes a buck converter circuit and a boost converter circuit; The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery. The output terminal of the buck converter circuit and the output terminal of the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

8. A bidirectional DC-DC converter, characterized in that, The bidirectional DC-DC converter includes a buck converter circuit and a boost converter circuit; The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery. The output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to the DC terminal of the bidirectional inverter circuit.

9. A photovoltaic energy storage system, characterized in that, The photovoltaic energy storage system includes a bidirectional DC-DC converter and a bidirectional micro inverter; The bidirectional DC-DC converter includes a buck converter circuit and a boost converter circuit; The input terminal of the buck converter circuit is used to connect to the photovoltaic power source, and the input terminal of the boost converter circuit is used to connect to the energy storage battery. The output terminals of the buck converter circuit and the boost converter circuit are connected in parallel to the DC terminal of the bidirectional microinverter.

10. The photovoltaic energy storage system according to claim 9, characterized in that, The bidirectional DC-DC converter also includes a first controller; The bidirectional microinverter includes a second controller; The second controller is communicatively connected to the first controller, and the second controller is used to send control signals to the first controller; The first controller is connected to the buck converter circuit and the boost converter circuit respectively. The first controller is used to send corresponding drive signals to the buck converter circuit and the boost converter circuit respectively according to the control signal.

Images