Inverter topological structure and photovoltaic inverter
By introducing an LCL filtering circuit into the inverter topology, the existing inverter output ripple is solved, and the switching stress and loss are increased in high-frequency states, achieving a more efficient filtering effect and lower power loss.
Patent Information
- Application Number
- CN202420893333.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-27
- Publication Date
- 2025-03-18
- Estimated Expiration
- 2034-04-27
AI Technical Summary
The existing inverter topology has shortcomings in suppressing leakage current, improving efficiency and reducing switching losses, especially in the high-frequency state where the output ripple is large and the switching stress and loss are increased.
The inverter topology structure is adopted, including a DC interface, a six-switch single-phase bridge inverter circuit, an LCL filter circuit and an AC interface, and the inverter output voltage is filtered through the LCL filter circuit.
It effectively improves the attenuation characteristics of the filter in the high frequency band, while maintaining the gain characteristics of the low frequency band, reducing equipment cost and volume, improving the filtering effect of harmonics, making the output voltage closer to a pure sine waveform, reducing reactive power and power loss, and is suitable for low switching frequency and high power applications.
Smart Images
Figure CN222638406U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of inverters, and in particular to an inverter topology structure and a photovoltaic inverter. Background Art
[0002] In order to eliminate the leakage current between the grid and the photovoltaic system and to improve the inverter output efficiency, power quality and other performance, various inverter topologies have been proposed and widely used, among which the most representative are the H4 and H5 topologies.
[0003] Among them, the unipolar modulation H4 topology cannot effectively suppress leakage current, while the bipolar modulation H4 topology inverter can suppress leakage current, but due to its high frequency state, the switching stress and switching loss increase and the output ripple is large. Although the H5 topology effectively suppresses leakage current, it has low efficiency and large switching loss.
[0004] The above problems need to be solved urgently. Utility Model Content
[0005] The purpose of the utility model is to provide an inverter topology structure and a photovoltaic inverter.
[0006] In order to solve the above technical problems, the utility model provides an inverter topology structure, including:
[0007] DC interface, six-switch single-phase bridge inverter circuit, LCL filter circuit and AC interface
[0008] The DC input side of the six-switch single-phase bridge inverter circuit is electrically connected to the DC interface;
[0009] The inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the AC interface after being filtered by the filter circuit.
[0010] Further, the LCL filter circuit includes a first filter inductor L1, a second filter inductor L2 and a filter capacitor C4;
[0011] The first output end of the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the first end of the AC interface after passing through the first filter inductor L1 and the second filter inductor L2 in sequence;
[0012] The second output end of the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the second end of the AC interface;
[0013] One end of the filter capacitor C4 is electrically connected between the first filter inductor L1 and the second filter inductor L2, and the other end is electrically connected between the second output end of the inverter output side of the six-switch single-phase bridge inverter circuit and the second end of the AC interface.
[0014] Furthermore, the LCL filter circuit also includes a first parasitic resistor R1;
[0015] The first parasitic resistor R1 is connected in series between the first output terminal of the inverter output side of the six-switch single-phase bridge inverter circuit and the first filter inductor L1.
[0016] Furthermore, the LCL filter circuit also includes a second parasitic resistor R2;
[0017] The second parasitic resistor R2 is connected in series between the first filter inductor L1 and the second filter inductor L2; and
[0018] One end of the filter capacitor C4 is electrically connected between the first filter inductor L1 and the second parasitic resistor R2 .
[0019] Furthermore, the six-switch single-phase bridge inverter circuit includes:
[0020] Switch tube S1, switch tube S2, switch tube S3, switch tube S4, switch tube S5 and switch tube S6;
[0021] The collector of the switch tube S1 is electrically connected to the positive electrode interface of the DC interface;
[0022] The emitter of the switch tube S1 is electrically connected to the collector of the switch tube S2;
[0023] The emitter of the switch tube S2 is electrically connected to the negative electrode interface of the DC interface;
[0024] The switch tube S3 and the switch tube S4 are connected in series and then connected in parallel with the switch tube S1;
[0025] The switch tubes S5 and S6 are connected in series and then in parallel with the switch tube S1;
[0026] The first output end of the inverter output side of the six-switch single-phase bridge inverter circuit is led out between the switch tube S3 and the switch tube S4;
[0027] The second output end of the inverter output side of the six-switch single-phase bridge inverter circuit is led out from between the switch tube S5 and the switch tube S6.
[0028] Furthermore, the inverter topology structure also includes an anti-reverse diode D1 and a protection capacitor C3;
[0029] The anti-reverse diode D1 is connected in series between the DC interface and the DC input side of the six-switch single-phase bridge inverter circuit;
[0030] The protection capacitor C3 is connected in parallel with the anti-reverse diode D1.
[0031] Furthermore, the inverter topology structure also includes a DC voltage dividing capacitor C1;
[0032] The DC voltage dividing capacitor C1 is connected in parallel to the DC interface.
[0033] Furthermore, the inverter topology structure also includes a common mode loop;
[0034] Two ends of the common mode loop are electrically connected to the negative electrode interface of the DC interface and the second end of the AC interface respectively.
[0035] Further, the common mode loop includes a parasitic capacitor C2 and an impedance Z1;
[0036] The parasitic capacitor C2 is connected in series with the impedance Z1 and connected between the negative electrode interface of the DC interface and the second end of the AC interface.
[0037] The utility model also provides a photovoltaic inverter, comprising:
[0038] A box and an inverter topology as described above;
[0039] The inverter topology structure is arranged in the box;
[0040] The DC interface and the AC interface are fixedly arranged on the outer side wall of the box.
[0041] The utility model provides an inverter topology structure and a photovoltaic inverter, wherein the inverter topology structure includes: a DC interface, a six-switch single-phase bridge inverter circuit, an LCL filter circuit and an AC interface; the DC input side of the six-switch single-phase bridge inverter circuit is electrically connected to the DC interface; the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the AC interface after filtering by the filter circuit. By setting the LCL filter circuit to filter the output voltage of the inverter topology structure, the attenuation characteristics of the filter in the high frequency band are effectively improved, while maintaining a good gain characteristic in the low frequency band, and compared with the L-type filter, the equipment cost and volume are significantly reduced, the filtering effect on harmonics is improved, the output voltage is closer to a pure sine waveform, the reactive power is lower, the power loss is smaller, and the voltage stress between switches is reduced, which is suitable for low switching frequency and high power applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The utility model is further described below in conjunction with the accompanying drawings and embodiments.
[0043] Figure 1 It is a circuit diagram of the inverter topology structure provided by an embodiment of the utility model.
[0044] Figure 2 It is a circuit diagram of the inverter topology structure provided by the embodiment of the utility model when it is in working mode 1.
[0045] Figure 3 It is a circuit diagram of the inverter topology structure provided by the embodiment of the utility model when it is in working mode 2.
[0046] Figure 4 It is a circuit diagram of the inverter topology structure provided by the embodiment of the utility model when it is in working mode 3.
[0047] Figure 5 It is a circuit diagram of the inverter topology structure provided by the embodiment of the utility model when it is in working mode 4. DETAILED DESCRIPTION
[0048] Now the utility model is further described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the utility model in a schematic manner, and therefore only show the components related to the utility model.
[0049] For examples, see Figure 1 This embodiment provides an inverter topology structure, including: a DC interface, a six-switch single-phase bridge inverter circuit, an LCL filter circuit and an AC interface; the DC input side of the six-switch single-phase bridge inverter circuit is electrically connected to the DC interface; the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the AC interface after filtering by the filter circuit. By setting the LCL filter circuit to filter the output voltage of the inverter topology structure, the filtering effect of harmonics is improved, the output voltage is closer to a pure sine waveform, the reactive power is lower, the power loss is smaller, and the voltage stress between switches is reduced, which is suitable for low switching frequency and high power applications.
[0050] The composition of the LCL filter circuit is described below. The LCL filter circuit includes a first filter inductor L1, a second filter inductor L2, and a filter capacitor C4; the first output end of the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the first end of the AC interface after passing through the first filter inductor L1 and the second filter inductor L2 in sequence; the second output end of the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the second end of the AC interface; one end of the filter capacitor C4 is electrically connected between the first filter inductor L1 and the second filter inductor L2, and the other end is electrically connected between the second output end of the inverter output side of the six-switch single-phase bridge inverter circuit and the second end of the AC interface. By setting the LCL filter circuit, the attenuation characteristics in the high frequency band are effectively improved, while maintaining a good gain characteristic in the low frequency band, and compared with the L-type filter, the equipment cost and volume are significantly reduced.
[0051] The LCL filter circuit further includes a first parasitic resistor R1; the first parasitic resistor R1 is connected in series between the first output end of the inverter output side of the six-switch single-phase bridge inverter circuit and the first filter inductor L1. The LCL filter circuit further includes a second parasitic resistor R2; the second parasitic resistor R2 is connected in series between the first filter inductor L1 and the second filter inductor L2; and one end of the filter capacitor C4 is electrically connected between the first filter inductor L1 and the second parasitic resistor R2.
[0052] The structure of the six-switch single-phase bridge inverter circuit is described below. The six-switch single-phase bridge inverter circuit includes: a switch tube S1, a switch tube S2, a switch tube S3, a switch tube S4, a switch tube S5 and a switch tube S6; the collector of the switch tube S1 is electrically connected to the positive interface of the DC interface; the emitter of the switch tube S1 is electrically connected to the collector of the switch tube S2; the emitter of the switch tube S2 is electrically connected to the negative interface of the DC interface; the switch tubes S3 and S4 are connected in series and then connected in parallel with the switch tube S1; the switch tubes S5 and S6 are connected in series and then connected in parallel with the switch tube S1; the first output end of the inverter output side of the six-switch single-phase bridge inverter circuit is led out from between the switch tubes S3 and S4; the second output end of the inverter output side of the six-switch single-phase bridge inverter circuit is led out from between the switch tubes S5 and S6.
[0053] In this embodiment, the inverter topology structure further includes an anti-reverse diode D1 and a protection capacitor C3; the anti-reverse diode D1 is connected in series between the DC interface and the DC input side of the six-switch single-phase bridge inverter circuit; the protection capacitor C3 is connected in parallel with the anti-reverse diode D1. The inverter topology structure is protected by providing the anti-reverse diode D1, and the anti-reverse diode D1 is protected by the protection capacitor C3.
[0054] In this embodiment, the inverter topology structure further includes a DC voltage-dividing capacitor C1; the DC voltage-dividing capacitor C1 is connected in parallel to the DC interface.
[0055] In this embodiment, the inverter topology structure further includes a common mode loop; two ends of the common mode loop are electrically connected to the negative electrode interface of the DC interface and the second end of the AC interface respectively.
[0056] The common mode loop includes a parasitic capacitor C2 and an impedance Z1; the parasitic capacitor C2 and the impedance Z1 are connected in series and connected between the negative electrode interface of the DC interface and the second end of the AC interface.
[0057] It should be noted that the inverter topology includes 4 working modes, such as Figure 2-Figure 5 As shown, the arrow indicates the direction of current, the gray line has no current passing through it, and the black line has current passing through it.
[0058] See also Figure 2 , Working mode 1: The DC interface voltage is positive, the switch tubes S2, S3, and S6 are turned on, and the switch tubes S1, S4, and S5 are turned off. The AC interface current I>0, and flows through the anti-reverse diode D1, the switch tube S3, the first parasitic resistor R1, the first filter inductor L1, the filter capacitor C4, the second parasitic resistor R2, the second filter inductor L2, the AC interface, the switch tube S6, and the switch tube S2 in sequence.
[0059] See also Figure 3 , Working mode 2: switch tube S1 is turned on, switch tube S2, switch tube S3, switch tube S5, switch tube S4, and switch tube S6 are turned off. The grid current I>0 of the freewheeling loop flows through the anti-parallel diode of switch tube S5, switch tube S1, anti-parallel diode of switch tube S4, first parasitic resistor R1, first filter inductor L1, filter capacitor C4, second parasitic resistor R2, filter inductor L2, and AC interface.
[0060] See also Figure 4, Working mode 3: The DC interface voltage is negative, the switch tubes S2, S4, and S5 are turned on, and the switch tubes S1, S3, and S6 are turned off. The grid current I<0 flows through the anti-reverse diode D1, the switch tube S5, the filter capacitor C4, the AC interface, the second filter inductor L2, the second parasitic resistor R2, the first filter inductor L1, the first parasitic resistor R1, the switch tube S4, and the switch tube S2 in sequence.
[0061] See also Figure 5 , Working mode 4: switch tube S1 is turned on, switch tube S2, switch tube S3, switch tube S5, switch tube S4, and switch tube S6 are turned off. The grid current I of the freewheeling loop is less than 0, and flows through the anti-parallel diode of switch tube S3, switch tube S1, anti-parallel diode of switch tube S6, filter capacitor C4, AC interface, second filter inductor L2, second parasitic resistor R2, first filter inductor L1, first parasitic resistor R1, switch tube S4, and switch tube S2.
[0062] This embodiment further provides a photovoltaic inverter, comprising: a box and the inverter topology structure as described above; the inverter topology structure is arranged in the box; the DC interface and the AC interface are fixedly arranged on the outer wall of the box.
[0063] The beneficial effect of the utility model is that the utility model provides an inverter topology structure and a photovoltaic inverter, wherein the inverter topology structure includes: a DC interface, a six-switch single-phase bridge inverter circuit, an LCL filter circuit and an AC interface; the DC input side of the six-switch single-phase bridge inverter circuit is electrically connected to the DC interface; the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the AC interface after filtering by the filter circuit. By setting the LCL filter circuit to filter the output voltage of the inverter topology structure, the attenuation characteristics of the filter in the high frequency band are effectively improved, while maintaining a good gain characteristic in the low frequency band, and compared with the L-type filter, the equipment cost and volume are significantly reduced, the filtering effect on harmonics is improved, the output voltage is closer to a pure sine waveform, the reactive power is lower, the power loss is smaller, and the voltage stress between switches is reduced, which is suitable for low switching frequency and high power applications.
[0064] All devices (parts without specific structure) selected in this application are universal standard parts or parts known to those skilled in the art, and their structures and principles can be known by those skilled in the art through technical manuals or conventional experimental methods. In addition, the software programs involved in this application are all prior art, and this application does not involve any improvement to the software programs.
[0065] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0066] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0067] In the several embodiments provided in 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 schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For 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 mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.
[0068] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
[0069] In addition, each functional unit in each embodiment of the present utility model may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
[0070] Based on the above ideal embodiments of the utility model, the relevant staff can make various changes and modifications without deviating from the technical concept of the utility model through the above description. The technical scope of the utility model is not limited to the content of the specification, and its technical scope must be determined according to the scope of the claims.
Claims
1. An inverter topology structure, characterized in that: include: DC interface, six-switch single-phase bridge inverter circuit, LCL filter circuit and AC interface; The DC input side of the six-switch single-phase bridge inverter circuit is electrically connected to the DC interface; The inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the AC interface after being filtered by the filter circuit.
2. The inverter topology structure according to claim 1, characterized in that: The LCL filter circuit includes a first filter inductor L1, a second filter inductor L2 and a filter capacitor C4; The first output end of the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the first end of the AC interface after passing through the first filter inductor L1 and the second filter inductor L2 in sequence; The second output end of the inverter output side of the six-switch single-phase bridge inverter circuit is electrically connected to the second end of the AC interface; One end of the filter capacitor C4 is electrically connected between the first filter inductor L1 and the second filter inductor L2, and the other end is electrically connected between the second output end of the inverter output side of the six-switch single-phase bridge inverter circuit and the second end of the AC interface.
3. The inverter topology structure according to claim 2, characterized in that: The LCL filter circuit also includes a first parasitic resistor R1; The first parasitic resistor R1 is connected in series between the first output terminal of the inverter output side of the six-switch single-phase bridge inverter circuit and the first filter inductor L1.
4. The inverter topology structure according to claim 2, characterized in that: The LCL filter circuit also includes a second parasitic resistor R2; The second parasitic resistor R2 is connected in series between the first filter inductor L1 and the second filter inductor L2; and One end of the filter capacitor C4 is electrically connected between the first filter inductor L1 and the second parasitic resistor R2 .
5. The inverter topology structure according to claim 1, characterized in that: The six-switch single-phase bridge inverter circuit comprises: Switch tube S1, switch tube S2, switch tube S3, switch tube S4, switch tube S5 and switch tube S6; The collector of the switch tube S1 is electrically connected to the positive electrode interface of the DC interface; The emitter of the switch tube S1 is electrically connected to the collector of the switch tube S2; The emitter of the switch tube S2 is electrically connected to the negative electrode interface of the DC interface; The switch tube S3 and the switch tube S4 are connected in series and then connected in parallel with the switch tube S1; The switch tubes S5 and S6 are connected in series and then in parallel with the switch tube S1; The first output end of the inverter output side of the six-switch single-phase bridge inverter circuit is led out between the switch tube S3 and the switch tube S4; The second output end of the inverter output side of the six-switch single-phase bridge inverter circuit is led out from between the switch tube S5 and the switch tube S6.
6. The inverter topology structure according to claim 1, characterized in that: The inverter topology structure also includes an anti-reverse diode D1 and a protection capacitor C3; The anti-reverse diode D1 is connected in series between the DC interface and the DC input side of the six-switch single-phase bridge inverter circuit; The protection capacitor C3 is connected in parallel with the anti-reverse diode D1.
7. The inverter topology structure according to claim 1, characterized in that: The inverter topology structure also includes a DC voltage dividing capacitor C1; The DC voltage dividing capacitor C1 is connected in parallel to the DC interface.
8. The inverter topology structure according to claim 1, characterized in that: The inverter topology structure also includes a common mode loop; Two ends of the common mode loop are electrically connected to the negative electrode interface of the DC interface and the second end of the AC interface respectively.
9. The inverter topology structure according to claim 8, characterized in that: The common mode loop includes a parasitic capacitor C2 and an impedance Z1; The parasitic capacitor C2 is connected in series with the impedance Z1 and connected between the negative electrode interface of the DC interface and the second end of the AC interface.
10. A photovoltaic inverter, characterized in that: include: A box and an inverter topology structure as claimed in any one of claims 1 to 9; The inverter topology structure is arranged in the box; The DC interface and the AC interface are fixedly arranged on the outer side wall of the box.