CN213426026U - Photovoltaic grid-connected inverter based on flexible switching - Google Patents
Photovoltaic grid-connected inverter based on flexible switching Download PDFInfo
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Abstract
A photovoltaic grid-connected inverter based on flexible switching comprises a solar panel module, a high-boost converter circuit, a flexible switching circuit, a rectifier bridge circuit, a filter circuit and a power grid module. The utility model discloses compare with traditional photovoltaic grid-connected inverter, this topological structure adopts the flexible switching of quasi-resonance formula direct current chain, makes rectifier bridge circuit's power switch tube device switch on under zero voltage, reduces switching element's switching loss and electromagnetic interference, improves photovoltaic grid-connected inverter's conversion efficiency, has very high voltage gain and voltage regulation rate, guarantees little volume, stability and economic nature, and application prospect is very extensive.
Description
Technical Field
The utility model relates to a photovoltaic power generation technical field, concretely relates to photovoltaic grid-connected inverter based on flexible switching.
Background
With the increasing exhaustion of fossil energy, a series of environmental pollution problems such as greenhouse effect come with the fossil energy, so that people are continuously exploring and researching new energy in the face of severe energy crisis, wherein solar energy occupies an important part in energy research of various countries due to the characteristics of environmental friendliness, convenience in conversion, inexhaustibility and the like. Therefore, it is necessary to improve the photovoltaic conversion efficiency and reduce the electromagnetic interference, so the research and design of the photovoltaic grid-connected inverter has great application significance and market value.
The traditional hard switching photovoltaic grid-connected inverter usually increases the switching frequency in order to reduce the size and the quality of the inverter, but the higher switching frequency increases the switching loss of a power switching device, so that the heat dissipation problem of the switching device is caused, the electromagnetic interference is increased, and the power supply quality and the normal work of a power system are influenced. Therefore, the problem of low efficiency of the photovoltaic grid-connected inverter needs to be solved, and small size, stability and economy are guaranteed.
Disclosure of Invention
In view of this, the utility model aims at providing a photovoltaic grid-connected inverter based on flexible switching compares with traditional photovoltaic grid-connected inverter, and rectifier bridge circuit's power switch tube device switches on under zero voltage, reduces switching element's switching loss and electromagnetic interference, improves photovoltaic grid-connected inverter's conversion efficiency to adopt high boost converter, have very high voltage gain and voltage adjustment rate, guarantee small volume, stability and economic nature, application prospect is very extensive.
The utility model discloses the technical scheme who takes does: a photovoltaic grid-connected inverter based on flexible switching comprises a solar panel module, a high-boost converter circuit, a flexible switching circuit, a rectifier bridge circuit, a filter circuit and a power grid module; the output of the solar panel module is connected with the high-boost converter circuit, the output of the high-boost converter circuit is connected with the flexible switching circuit, the output of the flexible switching circuit is connected with the rectifier bridge circuit, the output of the rectifier bridge circuit is connected with the filter circuit, and the output of the filter circuit is connected with the power grid module; the solar panel module comprises a direct-current input power Vin; the high-boost converter circuit comprises an inductor L1, an inductor L2, a coupling inductor Lm, a coupling inductor Ln, a diode VD1, a diode VD2, a diode VD3, a power MOSFET S, a capacitor Co, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4; the flexible switching circuit comprises a coupling inductor Ls1, a coupling inductor Ls2, a diode VDs, a power MOSFET (metal-oxide-semiconductor field effect transistor) QS, a capacitor Cdc and a capacitor Cs; the rectifier bridge circuit comprises a power MOSFET tube S1, a power MOSFET tube S2, a power MOSFET tube S3, a power MOSFET tube S4, a power MOSFET tube S5 and a power MOSFET tube S6; the filter circuit comprises a filter inductor LE and a filter capacitor CE.
The output of the solar panel module is direct current of 17V.
One end of an inductor L1 of the high-boost converter circuit is connected with the solar panel module, the other end of an inductor L1 is connected with a coupling inductor Lm and an inductor L2, and the other ends of the coupling inductor Lm and the inductor L2 are connected with a point a; one end of the power MOSFET tube S is connected with the point a, one end of the capacitor C1 is connected with the point b, one end of the capacitor Co is connected with the point C, and the other ends of the power MOSFET tube S, the capacitor C1 and the capacitor Co are connected with the point e; the anode of the diode VD1 is connected with the point a, and the cathode of the diode VD1 is connected with the point b; one end of the capacitor C2 and one end of the coupling inductor Ln are connected with a point b, the other end of the capacitor C2 and the other end of the coupling inductor Ln are connected with the anode of the diode VD3 and the capacitor C3, the cathode of the diode VD3 and the other end of the capacitor C3 are connected with the anode of the diode VD2, and the cathode of the diode VD2 is connected with a point C.
One end of a capacitor Cdc of the flexible switching circuit is connected with the point c, one end of a capacitor Cs is connected with the point d, and the other ends of the capacitor Cdc and the capacitor Cs are connected with the point e; one ends of a coupling inductor Ls1 and a coupling inductor Ls2 are connected with a point c, the other end of the coupling inductor Ls1 is connected with a power MOSFET tube QS, and the other end of the power MOSFET tube QS is connected with a point d; the other end of the coupling inductor Ls2 is connected to the cathode of the diode VDs, and the anode of the diode VDs is connected to the point d.
One end of a power MOSFET tube S1 of the rectifier bridge circuit is connected with a power MOSFET tube S4, one end of a power MOSFET tube S2 is connected with a power MOSFET tube S5, one end of the power MOSFET tube S3 is connected with a power MOSFET tube S6, and the other ends of the power MOSFET tube S1, the power MOSFET tube S2 and the power MOSFET tube S3 are connected with a point d; the other ends of the power MOSFET S4, the power MOSFET S5 and the power MOSFET S6 are connected to the point e.
One end of a filter inductor LE of the filter circuit is connected with the middle point of a bridge arm of the rectifier bridge circuit, and the other end of the filter inductor LE is connected with the power grid module; one end of the filter capacitor CE is connected with the filter inductor LE respectively, and the other end of the filter capacitor CE is connected to the point f.
The utility model relates to a photovoltaic grid-connected inverter based on flexible switching has following advantage: the utility model discloses a flexible switching of quasi-resonance formula direct current chain makes the power switch tube device of rectifier bridge circuit switch on under zero voltage, reduces switching element's switching loss and electromagnetic interference, and auxiliary circuit can guarantee that resonance electric capacity Cs discharges to zero among the flexible switching circuit, improves photovoltaic grid-connected inverter's conversion efficiency, and the adoption combines coupling inductance and voltage lift technique's high boost converter, has very high voltage gain and voltage adjustment rate, guarantees little volume, stability and economic nature.
Drawings
Fig. 1 is the utility model discloses a photovoltaic grid-connected inverter's circuit structure chart based on flexible switching.
Fig. 2 is the equivalent circuit diagram of the photovoltaic grid-connected inverter conduction mode 1 based on the flexible switching (t is not less than t1 and not more than t 2).
Fig. 3 is an equivalent circuit diagram of the photovoltaic grid-connected inverter conduction mode 2 based on flexible switching (t 2 is not less than t 3).
Fig. 4 is an equivalent circuit diagram of the photovoltaic grid-connected inverter conduction mode 3 based on flexible switching (t 3 is not less than t 4).
Fig. 5 is an equivalent circuit diagram of the photovoltaic grid-connected inverter conduction mode 4 based on flexible switching (t 4 is not less than t 5).
Fig. 6 is an equivalent circuit diagram of the photovoltaic grid-connected inverter conduction mode 5 based on flexible switching (t 5 is not less than t 6).
Fig. 7 is an equivalent circuit diagram of the photovoltaic grid-connected inverter conduction mode 6 based on flexible switching (t 6 is not less than t 7).
Detailed Description
Fig. 1 shows a photovoltaic grid-connected inverter based on flexible switching, which includes a solar panel module, a high-boost converter circuit, a flexible switching circuit, a rectifier bridge circuit, a filter circuit, and a power grid module; the output of the solar panel module is connected with the high-boost converter circuit, the output of the high-boost converter circuit is connected with the flexible switching circuit, the output of the flexible switching circuit is connected with the rectifier bridge circuit, the output of the rectifier bridge circuit is connected with the filter circuit, and the output of the filter circuit is connected with the power grid module; the solar panel module comprises a direct-current input power Vin; the high-boost converter circuit comprises an inductor L1, an inductor L2, a coupling inductor Lm, a coupling inductor Ln, a diode VD1, a diode VD2, a diode VD3, a power MOSFET S, a capacitor Co, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4; the flexible switching circuit comprises a coupling inductor Ls1, a coupling inductor Ls2, a diode VDs, a power MOSFET (metal-oxide-semiconductor field effect transistor) QS, a capacitor Cdc and a capacitor Cs; the rectifier bridge circuit comprises a power MOSFET tube S1, a power MOSFET tube S2, a power MOSFET tube S3, a power MOSFET tube S4, a power MOSFET tube S5 and a power MOSFET tube S6; the filter circuit comprises a filter inductor LE and a filter capacitor CE.
The output of the solar panel module is direct current of 17V.
One end of an inductor L1 of the high-boost converter circuit is connected with the solar panel module, the other end of an inductor L1 is connected with a coupling inductor Lm and an inductor L2, and the other ends of the coupling inductor Lm and the inductor L2 are connected with a point a; one end of the power MOSFET tube S is connected with the point a, one end of the capacitor C1 is connected with the point b, one end of the capacitor Co is connected with the point C, and the other ends of the power MOSFET tube S, the capacitor C1 and the capacitor Co are connected with the point e; the anode of the diode VD1 is connected with the point a, and the cathode of the diode VD1 is connected with the point b; one end of the capacitor C2 and one end of the coupling inductor Ln are connected with a point b, the other end of the capacitor C2 and the other end of the coupling inductor Ln are connected with the anode of the diode VD3 and the capacitor C3, the cathode of the diode VD3 and the other end of the capacitor C3 are connected with the anode of the diode VD2, and the cathode of the diode VD2 is connected with a point C.
One end of a capacitor Cdc of the flexible switching circuit is connected with the point c, one end of a capacitor Cs is connected with the point d, and the other ends of the capacitor Cdc and the capacitor Cs are connected with the point e; one ends of a coupling inductor Ls1 and a coupling inductor Ls2 are connected with a point c, the other end of the coupling inductor Ls1 is connected with a power MOSFET tube QS, and the other end of the power MOSFET tube QS is connected with a point d; the other end of the coupling inductor Ls2 is connected to the cathode of the diode VDs, and the anode of the diode VDs is connected to the point d.
One end of a power MOSFET tube S1 of the rectifier bridge circuit is connected with a power MOSFET tube S4, one end of a power MOSFET tube S2 is connected with a power MOSFET tube S5, one end of the power MOSFET tube S3 is connected with a power MOSFET tube S6, and the other ends of the power MOSFET tube S1, the power MOSFET tube S2 and the power MOSFET tube S3 are connected with a point d; the other ends of the power MOSFET S4, the power MOSFET S5 and the power MOSFET S6 are connected to the point e.
One end of a filter inductor LE of the filter circuit is connected with the middle point of a bridge arm of the rectifier bridge circuit, and the other end of the filter inductor LE is connected with the power grid module; one end of the filter capacitor CE is connected with the filter inductor LE respectively, and the other end of the filter capacitor CE is connected to the point f.
For clearer explanation, the present invention provides a photovoltaic grid-connected inverter based on flexible switching, and the following description is made in detail with reference to the accompanying drawings and the detailed description of the present invention. The utility model discloses topological structure adopts the flexible switching of quasi-resonance formula direct current chain, can utilize SVPWM to control, direct current through the high boost converter passes through direct current chain switch power MOSFET pipe QS, resonance electric capacity Cs and rectifier bridge are parallelly connected, when the power MOSFET pipe on-off state of rectifier bridge changes, direct current chain switch QS will cut off, resonance electric capacity Cs discharges via auxiliary circuit this moment, therefore, can be before rectifier bridge on-off switching state, make it switch on under zero voltage, reach the ZVS effect. And the resonant capacitor Cs and the auxiliary circuit can overcome the defect that the traditional flexible switching circuit cannot ensure that the resonant capacitor discharges to zero, and the conversion efficiency of the photovoltaic grid-connected inverter is improved.
Fig. 2 shows an equivalent circuit diagram of the conduction mode 1 (t 1 ≦ t 2), and since the switching frequency is much higher than the grid frequency, the grid module is replaced by a current source Io, and the rectifier bridge is equivalent to a switching element for simplified analysis. At t1, QS IS turned on, and due to the presence of coupling inductor Ls1, QS IS turned on at zero current ZCS, and current iLs1 flowing through coupling inductor Ls1 increases linearly to be in conduction mode 2 at IS 1.
Fig. 3 is an equivalent circuit diagram of the on-mode 2 (t 2 ≦ t 3), at t2, the rectifier bridge equivalent switch S1 is turned off, and at this time, the voltage across the resonant capacitor Cs is zero, so the switch S1 is turned off at zero voltage, the coupling inductor Ls1 and the resonant capacitor Cs resonate, and the resonant capacitor Cs is charged until the voltage across the resonant capacitor Cs is equal to Vin.
Fig. 4 is an equivalent circuit diagram of the conduction mode 3 (t 3 is not less than t 4), at t3, the voltage across the resonant capacitor Cs is equal to Vin, the diode VDs is turned on, the leakage flux of the coupling inductor Ls1 is transferred to the coupling inductor Ls2, and the energy at the dc end is transmitted to the load end of the power grid.
Fig. 5 is an equivalent circuit diagram of the conduction mode 4 (t 4 ≦ t 5), where the dc link switch QS is turned off, and the resonant capacitor Cs discharges to zero through the coupling inductor Ls 2.
FIG. 6 is an equivalent circuit diagram of the conduction mode 5 (t 5 ≦ t 6), when the rectifier bridge equivalent switch S1 is turned on.
Fig. 7 is an equivalent circuit diagram of the conduction mode 6 (t is greater than or equal to t6 and less than or equal to t 7), and the circuit only includes the rectifier bridge equivalent switch S1 and the grid equivalent current source Io, and at this time, the photovoltaic grid-connected inverter has completed conduction under zero voltage ZVS. And then the power grid module is accessed by the filter circuit, so that the power switching tube device of the rectifier bridge circuit is conducted under zero voltage, the switching loss and the electromagnetic interference of the switching element are reduced, and the conversion efficiency of the photovoltaic grid-connected inverter is improved.
The embodiments of the present invention have been described, and the above embodiments are only illustrative, and not restrictive, so that the present invention is not limited to the above embodiments, and all persons skilled in the art can easily replace and change the technical solutions of the present invention without departing from the spirit and scope of the present invention.
Claims (6)
1. A photovoltaic grid-connected inverter based on flexible switching is characterized in that: the high-boost converter comprises a solar panel module, a high-boost converter circuit, a flexible switching circuit, a rectifier bridge circuit, a filter circuit and a power grid module; the output of the solar panel module is connected with the high-boost converter circuit, the output of the high-boost converter circuit is connected with the flexible switching circuit, the output of the flexible switching circuit is connected with the rectifier bridge circuit, the output of the rectifier bridge circuit is connected with the filter circuit, and the output of the filter circuit is connected with the power grid module; the solar panel module comprises a direct-current input power Vin; the high-boost converter circuit comprises an inductor L1, an inductor L2, a coupling inductor Lm, a coupling inductor Ln, a diode VD1, a diode VD2, a diode VD3, a power MOSFET S, a capacitor Co, a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4; the flexible switching circuit comprises a coupling inductor Ls1, a coupling inductor Ls2, a diode VDs, a power MOSFET (metal-oxide-semiconductor field effect transistor) QS, a capacitor Cdc and a capacitor Cs; the rectifier bridge circuit comprises a power MOSFET tube S1, a power MOSFET tube S2, a power MOSFET tube S3, a power MOSFET tube S4, a power MOSFET tube S5 and a power MOSFET tube S6; the filter circuit comprises a filter inductor LE and a filter capacitor CE.
2. The photovoltaic grid-connected inverter based on flexible switching as claimed in claim 1, wherein: the output of the solar panel module is direct current of 17V.
3. The photovoltaic grid-connected inverter based on flexible switching as claimed in claim 1, wherein: one end of an inductor L1 of the high-boost converter circuit is connected with the solar panel module, the other end of an inductor L1 is connected with a coupling inductor Lm and an inductor L2, and the other ends of the coupling inductor Lm and the inductor L2 are connected with a point a; one end of the power MOSFET tube S is connected with the point a, one end of the capacitor C1 is connected with the point b, one end of the capacitor Co is connected with the point C, and the other ends of the power MOSFET tube S, the capacitor C1 and the capacitor Co are connected with the point e; the anode of the diode VD1 is connected with the point a, and the cathode of the diode VD1 is connected with the point b; one end of the capacitor C2 and one end of the coupling inductor Ln are connected with a point b, the other end of the capacitor C2 and the other end of the coupling inductor Ln are connected with the anode of the diode VD3 and the capacitor C3, the cathode of the diode VD3 and the other end of the capacitor C3 are connected with the anode of the diode VD2, and the cathode of the diode VD2 is connected with a point C.
4. The photovoltaic grid-connected inverter based on flexible switching as claimed in claim 1, wherein: one end of a capacitor Cdc of the flexible switching circuit is connected with the point c, one end of a capacitor Cs is connected with the point d, and the other ends of the capacitor Cdc and the capacitor Cs are connected with the point e; one ends of a coupling inductor Ls1 and a coupling inductor Ls2 are connected with a point c, the other end of the coupling inductor Ls1 is connected with a power MOSFET tube QS, and the other end of the power MOSFET tube QS is connected with a point d; the other end of the coupling inductor Ls2 is connected to the cathode of the diode VDs, and the anode of the diode VDs is connected to the point d.
5. The photovoltaic grid-connected inverter based on flexible switching as claimed in claim 1, wherein: one end of a power MOSFET tube S1 of the rectifier bridge circuit is connected with a power MOSFET tube S4, one end of a power MOSFET tube S2 is connected with a power MOSFET tube S5, one end of the power MOSFET tube S3 is connected with a power MOSFET tube S6, and the other ends of the power MOSFET tube S1, the power MOSFET tube S2 and the power MOSFET tube S3 are connected with a point d; the other ends of the power MOSFET S4, the power MOSFET S5 and the power MOSFET S6 are connected to the point e.
6. The photovoltaic grid-connected inverter based on flexible switching as claimed in claim 1, wherein: one end of a filter inductor LE of the filter circuit is connected with the middle point of a bridge arm of the rectifier bridge circuit, and the other end of the filter inductor LE is connected with the power grid module; one end of the filter capacitor CE is connected with the filter inductor LE respectively, and the other end of the filter capacitor CE is connected to the point f.
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| CN112290792A (en) * | 2020-11-09 | 2021-01-29 | 哈尔滨理工大学 | Photovoltaic grid-connected inverter based on flexible switching |
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