Voltage-sharing device for optical storage inverter and optical storage inverter

Abstract

The utility model belongs to the technical field of equalization circuits, and particularly relates to a voltage-sharing device for an optical storage inverter and the optical storage inverter, and the voltage-sharing device for the optical storage inverter comprises at least two voltage-sharing capacitors and a voltage-sharing circuit. Wherein the voltage-sharing capacitors are sequentially connected to a bus in series, and the voltage-sharing circuit is electrically connected with the voltage-sharing capacitors; the voltage-sharing circuit is suitable for balancing the voltage value of each voltage-sharing capacitor; according to the utility model, the voltage-sharing circuit is matched with each voltage-sharing capacitor, so that the neutral-point voltage fluctuation of the bus is small, the service life of each voltage-sharing capacitor connected in series is prolonged, the control complexity of the voltage-sharing circuit is low, the number of components is small, the cost is low, and the voltage of each voltage-sharing capacitor connected in series on the bus is rapidly balanced.

Description

Technical Field

[0001] The utility model belongs to the technical field of balancing circuits, and particularly relates to a voltage equalizing device for a photovoltaic energy storage inverter and a photovoltaic energy storage inverter. Background Art

[0002] During the operation of a photovoltaic energy storage inverter, in order to smooth the voltage ripple of the DC bus or collect the midpoint voltage requirement, multiple capacitors need to be arranged in the current bus. However, the capacitors cannot always maintain voltage equalization. Once the voltage on the capacitors deviates, it will cause the circuit to work unstably, and even the capacitors may be burned out.

[0003] A related technology mentions an externally controlled capacitor series voltage equalizing circuit. However, this solution requires too many practical components, and even needs to be controlled by a DSP chip, resulting in high costs and being not conducive to quickly equalizing the bus capacitor voltage.

[0004] Therefore, it is urgent to develop a new voltage equalizing device for a photovoltaic energy storage inverter and a photovoltaic energy storage inverter to solve the above problems. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a voltage equalizing device for a photovoltaic energy storage inverter and a photovoltaic energy storage inverter.

[0006] To solve the above technical problems, the utility model provides a voltage equalizing device for a photovoltaic energy storage inverter, which includes: at least two voltage equalizing capacitors and a voltage equalizing circuit; wherein each of the voltage equalizing capacitors is sequentially connected in series on the bus, and the voltage equalizing circuit is electrically connected to each voltage equalizing capacitor; the voltage equalizing circuit is adapted to equalize the voltage values of each voltage equalizing capacitor.

[0007] Specifically, two voltage equalizing capacitors are provided, namely a first voltage equalizing capacitor and a second voltage equalizing capacitor; the voltage equalizing circuit includes: a first voltage equalizing resistor and a second voltage equalizing resistor; the first voltage equalizing resistor and the second voltage equalizing resistor are connected in series, the first voltage equalizing resistor is connected to the first voltage equalizing capacitor, and the second voltage equalizing resistor is connected to the second voltage equalizing capacitor; the node between the first voltage equalizing resistor and the second voltage equalizing resistor is connected to the node between the first voltage equalizing capacitor and the second voltage equalizing capacitor.

[0008] Specifically, the capacitance value of the first voltage equalizing capacitor is the same as that of the second voltage equalizing capacitor; the resistance value of the first voltage equalizing resistor is the same as that of the second voltage equalizing resistor.

[0009] Specifically, the voltage equalizing circuit further includes: a first triode and a second triode; the collector of the first triode is connected to the node between the first voltage equalizing capacitor and the first voltage equalizing resistor, the emitter of the first triode is connected to the emitter of the second triode, and the base of the first triode is connected to the base of the second triode; the collector of the second triode is connected to the node between the second voltage equalizing capacitor and the second voltage equalizing resistor; the node between the emitter of the first triode and the emitter of the second triode is connected to the node between the first voltage equalizing capacitor and the second voltage equalizing capacitor, and the node between the base of the first triode and the base of the second triode is connected to the node between the first voltage equalizing resistor and the second voltage equalizing resistor.

[0010] Specifically, the first triode is an NPN type triode, and the second triode is a PNP type triode.

[0011] Specifically, the collector of the first triode is connected to the node between the first voltage equalizing capacitor and the first voltage equalizing resistor through a first current limiting resistor.

[0012] Specifically, the collector of the second triode is connected to the node between the second voltage equalizing capacitor and the second voltage equalizing resistor through a second current limiting resistor.

[0013] Specifically, the resistance value of the first current limiting resistor is the same as that of the second current limiting resistor.

[0014] On the other hand, the present invention provides a photovoltaic energy storage inverter, which includes: a voltage equalizing device for a photovoltaic energy storage inverter as described above, a buck-boost circuit, and an inverter circuit; the buck-boost circuit, the voltage equalizing device for a photovoltaic energy storage inverter, and the inverter circuit are connected in sequence.

[0015] Specifically, the input end of the buck-boost circuit is connected to a battery or a photovoltaic panel; the output end of the inverter circuit is connected to a load or a power grid.

[0016] The beneficial effect of the present invention is that by setting the voltage equalizing circuit in cooperation with each voltage equalizing capacitor, the voltage fluctuation at the midpoint of the bus can be made smaller, the service life of each series-connected voltage equalizing capacitor can be extended, and the control complexity of the voltage equalizing circuit is low, the number of components is small, and the cost is low, realizing rapid equalization of the voltages of the series-connected voltage equalizing capacitors on the bus.

[0017] Other features and advantages of the present invention will be described in the following specification, and part of them will be obvious from the specification or understood by implementing the present invention.

[0018] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 is the circuit diagram of the voltage equalizing device for the photovoltaic energy storage inverter of the present invention;

[0021] Figure 2 is the structural schematic diagram of the photovoltaic energy storage inverter of the present invention.

[0022] In the figure:

[0023] C1, the first voltage equalizing capacitor; C2, the second voltage equalizing capacitor; R1, the first voltage equalizing resistor; R2, the second voltage equalizing resistor; R3, the first current limiting resistor; R4, the second current limiting resistor; S1, the first triode; S2, the second triode. Specific embodiments

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0025] Example 1. In this example, as Figure 1 shown, this example provides a voltage equalizing device for a photovoltaic energy storage inverter, which includes: at least two voltage equalizing capacitors and a voltage equalizing circuit; wherein each of the voltage equalizing capacitors is sequentially connected in series on the bus, and the voltage equalizing circuit is electrically connected to each voltage equalizing capacitor; the voltage equalizing circuit is adapted to balance the voltage values of each voltage equalizing capacitor.

[0026] In this example, by setting the voltage equalizing circuit in cooperation with each voltage equalizing capacitor, the voltage fluctuation at the midpoint of the bus can be made smaller, the service life of each series-connected voltage equalizing capacitor can be extended, and the control complexity of the voltage equalizing circuit is low, the number of components is small, and the cost is low, realizing rapid balancing of the voltages of each series-connected voltage equalizing capacitor on the bus.

[0027] In this embodiment, two said voltage-sharing capacitors are provided, namely a first voltage-sharing capacitor C1 and a second voltage-sharing capacitor C2; the voltage-sharing circuit includes: a first voltage-sharing resistor R1 and a second voltage-sharing resistor R2; the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2 are connected in series, the first voltage-sharing resistor R1 is connected to the first voltage-sharing capacitor C1, and the second voltage-sharing resistor R2 is connected to the second voltage-sharing capacitor C2; the node between the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2 is connected to the node between the first voltage-sharing capacitor C1 and the second voltage-sharing capacitor C2.

[0028] In this embodiment, the capacitance value of the first voltage-sharing capacitor C1 is the same as that of the second voltage-sharing capacitor C2; the resistance value of the first voltage-sharing resistor R1 is the same as that of the second voltage-sharing resistor R2.

[0029] In this embodiment, the voltage-sharing circuit further includes: a first triode S1 and a second triode S2; the collector of the first triode S1 is connected to the node between the first voltage-sharing capacitor C1 and the first voltage-sharing resistor R1, the emitter of the first triode S1 is connected to the emitter of the second triode S2, and the base of the first triode S1 is connected to the base of the second triode S2; the collector of the second triode S2 is connected to the node between the second voltage-sharing capacitor C2 and the second voltage-sharing resistor R2; the node between the emitter of the first triode S1 and the emitter of the second triode S2 is connected to the node between the first voltage-sharing capacitor C1 and the second voltage-sharing capacitor C2, and the node between the base of the first triode S1 and the base of the second triode S2 is connected to the node between the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2.

[0030] Specifically, by adding a first voltage-sharing resistor R1, a second voltage-sharing resistor R2, and a first triode S1 and a second triode S2 for clamping, it is possible to control the first voltage-sharing capacitor C1 and the second voltage-sharing capacitor C2 to maintain at half of the bus voltage, playing a voltage-sharing role.

[0031] Specifically, please refer to Figure 1 , the bus voltage is V bus , the midpoint voltage of the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2 is V N , the node voltage of the first voltage-sharing capacitor C1 and the second voltage-sharing capacitor C2 is V n .

[0032] Specifically, the first voltage-sharing capacitor C1 and the second voltage-sharing capacitor C2 are connected in series on the bus, and their specification parameters are the same. The voltage at the connection point of the emitters of the first triode S1 and the second triode S2 is also V n , due to the series voltage division of the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2, V N remains at half of the bus voltage V bus .

[0033] In this embodiment, the first triode S1 is an NPN-type triode, and the second triode S2 is a PNP-type triode.

[0034] In this embodiment, the collector of the first triode S1 is connected to the node between the first equalizing capacitor C1 and the first equalizing resistor R1 through a first current-limiting resistor R3.

[0035] In this embodiment, the collector of the second triode S2 is connected to the node between the second equalizing capacitor C2 and the second equalizing resistor R2 through a second current-limiting resistor R4.

[0036] In this embodiment, the resistance value of the first current-limiting resistor R3 is the same as that of the second current-limiting resistor R4.

[0037] Specifically, when the leakage currents of the first equalizing capacitor C1 and the second equalizing capacitor C2 are equal, the midpoint voltage V of the first equalizing capacitor C1 and the second equalizing capacitor C2 n is also half of the bus voltage V bus Then the emitter voltages of the first triode S1 and the second triode S2 are equal to the base voltages, and the first triode S1 and the second triode S2 are not turned on. At this time, the voltages of the two equalizing capacitors are maintained in balance.

[0038] Specifically, when the leakage currents of the first equalizing capacitor C1 and the second equalizing capacitor C2 are not equal, their internal equivalent resistances are not equal, and the midpoint voltage V of the two equalizing capacitors n is also not equal to half of the bus voltage V bus When the leakage current of the first equalizing capacitor C1 is greater than the leakage current of the second equalizing capacitor C2, the internal equivalent resistance of the first equalizing capacitor C1 is less than the internal equivalent resistance of the second equalizing capacitor C2. Then the voltage of the second equalizing capacitor C2 is greater than the voltage of the first equalizing capacitor C1. At this time, the midpoint voltage of the two equalizing capacitors is greater than half of the bus voltage. At the same time, the emitter voltage of the second triode S2 is higher than the base voltage. When the voltage difference reaches the conduction voltage drop, the second triode S2 is turned on. The excessive leakage current of the first equalizing capacitor C1 will flow from the emitter of the second triode S2 to the collector, and then flow to the reference ground through the second current-limiting resistor R4, reducing the voltage of the second equalizing capacitor C2, that is, reducing the midpoint voltage of the two equalizing capacitors. Finally, V n will tend to be half of the bus voltage, and the second triode S2 will be turned off, realizing the function of capacitor voltage equalization; when the leakage current of the first equalizing capacitor C1 is less than the leakage current of the second equalizing capacitor C2, the internal equivalent resistance of the first equalizing capacitor C1 is greater than the internal equivalent resistance of the second equalizing capacitor C2. Then the voltage of the second equalizing capacitor C2 is less than the voltage of the first equalizing capacitor C1. At this time, the midpoint voltage of the two equalizing capacitors is lower than the midpoint voltage V of the first equalizing resistor R1 and the second equalizing resistor R2 N, the base voltage of the first triode S1 is higher than the emitter voltage. When the voltage difference reaches the conduction voltage drop, the first triode S1 conducts, and a part of the current flows from the collector to the emitter of the first triode S1 through the first current-limiting resistor R3, and then flows to the second equalizing capacitor C2, causing the voltage of the second equalizing capacitor C2 to increase, that is, the voltage of the midpoint of the two equalizing capacitors increases. Finally, V n will tend to be half of the bus voltage, and the first triode S1 will turn off, realizing the function of capacitor voltage equalization.

[0039] Embodiment 2, on the basis of Embodiment 1, as Figures 1 to 2 shown, this embodiment provides a photovoltaic energy storage inverter, which includes: a voltage equalizing device for a photovoltaic energy storage inverter, a buck-boost circuit, and an inverter circuit provided in Embodiment 1; the buck-boost circuit, the voltage equalizing device for a photovoltaic energy storage inverter, and the inverter circuit are connected in sequence.

[0040] Specifically, the input end of the buck-boost circuit is connected to a battery or a photovoltaic panel; the output end of the inverter circuit is connected to a load or a power grid.

[0041] Specifically, the voltage equalizing device for a photovoltaic energy storage inverter can balance the voltage of the midpoint of the bus, and supply power to the load or connect to the power grid through the inverter circuit.

[0042] In summary, by setting a voltage equalizing circuit in cooperation with each equalizing capacitor, the present invention can make the voltage fluctuation of the midpoint of the bus smaller, extend the service life of each series-connected equalizing capacitor, and the control complexity of the voltage equalizing circuit is low, and the number of components is small, and the cost is low, realizing rapid equalization of the voltages of the series-connected equalizing capacitors on the bus.

[0043] Each device (components without specific structures) selected in this application is a general standard component or a component known to those skilled in the art, and its structure and principle can be known by those skilled in the art through technical manuals or obtained through conventional experimental methods. And, the software programs involved in this application are all prior arts, and this application does not involve any improvement to the software programs.

[0044] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0045] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0046] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some communication interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0047] The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0048] In addition, in each embodiment of the present utility model, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0049] Taking the above ideal embodiments of the present utility model as an inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this utility model. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A voltage balancing device for a photovoltaic storage inverter, characterized in that: include: At least two voltage balancing capacitors and a voltage balancing circuit; in The voltage balancing capacitors are connected in series to the busbar in sequence, and the voltage balancing circuit is electrically connected to the voltage balancing capacitors; The voltage balancing circuit is suitable for balancing the voltage values ​​of each voltage balancing capacitor.

2. The voltage balancing device for a photovoltaic power storage inverter according to claim 1, characterized in that: Two voltage balancing capacitors are provided, namely a first voltage balancing capacitor and a second voltage balancing capacitor; The voltage balancing circuit comprises: a first voltage balancing resistor and a second voltage balancing resistor; The first voltage balancing resistor is connected in series with the second voltage balancing resistor, the first voltage balancing resistor is connected to the first voltage balancing capacitor, and the second voltage balancing resistor is connected to the second voltage balancing capacitor; The node between the first balancing resistor and the second balancing resistor is connected to the node between the first balancing capacitor and the second balancing capacitor.

3. The voltage balancing device for a photovoltaic power storage inverter according to claim 2, characterized in that: The capacitance value of the first balancing capacitor is the same as the capacitance value of the second balancing capacitor; The resistance value of the first balancing resistor is the same as the resistance value of the second balancing resistor.

4. The voltage balancing device for a photovoltaic power storage inverter according to claim 3, characterized in that: The voltage balancing circuit further includes: a first triode and a second triode; The collector of the first triode is connected to the node between the first balancing capacitor and the first balancing resistor, the emitter of the first triode is connected to the emitter of the second triode, and the base of the first triode is connected to the base of the second triode; The collector of the second transistor is connected to a node between the second balancing capacitor and the second balancing resistor; The node between the emitter of the first transistor and the emitter of the second transistor is connected to the node between the first equalizing capacitor and the second equalizing capacitor, and the node between the base of the first transistor and the base of the second transistor is connected to the node between the first equalizing resistor and the second equalizing resistor.

5. The voltage balancing device for a photovoltaic power storage inverter according to claim 4, characterized in that: The first transistor is an NPN transistor, and the second transistor is a PNP transistor.

6. The voltage balancing device for a photovoltaic power storage inverter according to claim 5, characterized in that: The collector of the first transistor is connected to a node between the first balancing capacitor and the first balancing resistor via a first current limiting resistor.

7. The voltage balancing device for a photovoltaic power storage inverter according to claim 6, characterized in that: The collector of the second transistor is connected to a node between the second balancing capacitor and the second balancing resistor via a second current limiting resistor.

8. The voltage balancing device for a photovoltaic power storage inverter according to claim 7, characterized in that: The resistance value of the first current limiting resistor is the same as the resistance value of the second current limiting resistor.

9. A photovoltaic energy storage inverter, characterized in that: include: A voltage balancing device, a buck-boost circuit and an inverter circuit for a photovoltaic storage inverter as described in any one of claims 1 to 8; The buck-boost circuit, the voltage equalizing device for the photovoltaic storage inverter, and the inverter circuit are connected in sequence.

10. The photovoltaic energy storage inverter according to claim 9, characterized in that: The input end of the buck-boost circuit is connected to a battery or a photovoltaic panel; The output end of the inverter circuit is connected to a load or a power grid.

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