Boost power conversion circuit and photovoltaic inverter

Abstract

The utility model discloses a boost power conversion circuit and a photovoltaic inverter, and the boost power conversion circuit comprises a power supply, a first reactor, a first switching tube, a second switching tube, a first diode, a second diode, an output upper bus capacitor, an output lower bus capacitor, a flying capacitor, a third diode, a fourth diode, and a current limiting member. A power supply, a first reactor, a first switch tube and a second switch tube are connected in series, a first diode, a second diode, an output upper bus capacitor and an output lower bus capacitor are connected in series, and an anode of the first diode is connected between the first reactor and the first switch tube. The first end of the flying capacitor and the cathode of the fourth diode are connected between the first diode and the second diode, and the second end of the flying capacitor and the anode of the fourth diode are respectively connected between the output upper bus capacitor and the output lower bus capacitor through the third diode and the current limiting member. The anode of the third diode and the second end of the flying capacitor are connected between the first switch tube and the second switch tube.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit technical field especially relates to a kind of boost power conversion circuit and photovoltaic inverter. BACKGROUND

[0002] Boost power conversion (BOOST) circuit is used to transform input voltage into higher voltage and output, realize power conversion, with the development of technology, the demand for voltage level is higher and higher, in high voltage level demand, the traditional boost power conversion circuit exists the risk that circuit device is vulnerable to overvoltage damage. SUMMARY

[0003] The utility model solves the technical problem to provide a kind of boost power conversion circuit and photovoltaic inverter, to reduce the risk that circuit device is damaged.

[0004] Firstly, the utility model provides a kind of boost power conversion circuit, including power supply, first electric reactor, first switch tube, second switch tube, first diode, second diode, output upper bus capacitor and output lower bus capacitor, the power supply, first electric reactor, first switch tube and second switch tube are sequentially connected in series to form loop, the first diode, second diode, output upper bus capacitor and output lower bus capacitor are sequentially connected in series, the anode of the first diode is connected with the one end of the first electric reactor and the electric energy input end of the first switch tube, the electric energy output end of the first switch tube is connected with the negative pole of the power supply and output lower bus through the second switch tube, the cathode of the first diode is connected with the anode of the second diode, the cathode of the second diode and the first end of the output upper bus capacitor are connected with output upper bus, the second end of the output upper bus capacitor is connected with output lower bus, the electric energy output end of the second switch tube and the negative pole of the power supply through the output lower bus capacitor, the boost power conversion circuit further includes flying capacitor, third diode, fourth diode and current-limiting piece, the first end of the flying capacitor is electrically connected between first diode and second diode, the second end of the flying capacitor is electrically connected between the output upper bus capacitor and the output lower bus capacitor through the third diode, the anode of the third diode and the second end of the flying capacitor are electrically connected between the first switch tube and the second switch tube, the cathode of the fourth diode is electrically connected between the first diode and the second diode, the anode of the fourth diode is electrically connected between the output upper bus capacitor and the output lower bus capacitor through the current-limiting piece.

[0005] Secondly, the utility model also provides a kind of photovoltaic inverter, including the boost power conversion circuit described above.

[0006] The utility model discloses beneficial technical effects are at: the utility model discloses the boost power conversion circuit through the first end of the flying capacitor electric connection between the first diode and the second diode, and the second end of flying capacitor is electrically connected between the first switch tube and the second switch tube, the second end of flying capacitor is electrically connected between the output upper bus capacitor and the output lower bus capacitor through the third diode, to when the bus voltage has established and the bus voltage has not established, the third diode can clamp the voltage stress of the second switch tube to the voltage of the output lower bus capacitor, can effectively limit the voltage stress of the second switch tube, thereby effectively protecting the second switch tube, avoid overvoltage breakdown, combine the fourth diode of cathode electric connection between the first diode and the second diode, when the bus voltage has established and the power input has not powered on, the fourth diode clamps the voltage stress of the second diode to the output upper bus voltage, thereby guaranteeing that the second diode will only bear half bus voltage, effectively protecting the second diode, avoid overvoltage breakdown, by setting the current -limiting piece, can effectively limit the transient current of the fourth diode, protect the fourth diode and not be damaged due to the flying capacitor instability or bus voltage fluctuation eventually leads to its transient current too big, and then reduce the risk of the circuit device of overall circuit being damaged when high -voltage output. The photovoltaic inverter of the utility model also has the above-mentioned function. BRIEF DESCRIPTION OF DRAWINGS

[0007] In order to more clearly illustrate the technical scheme of the embodiment of the utility model, the following will briefly introduce the drawing needed to be used in the embodiment description, and obviously, the drawing in the following description is some embodiments of the utility model, and for those skilled in the art, under the premise of not creating labor, other drawings can also be obtained according to these drawings.

[0008] Figure 1 It is the circuit diagram of the first embodiment of the boost power conversion circuit of the utility model,

[0009] Figure 2 It is the circuit diagram of the second embodiment of the boost power conversion circuit of the utility model,

[0010] Figure 3 It is the circuit diagram of the third embodiment of the boost power conversion circuit of the utility model. DETAILED DESCRIPTION

[0011] The technical scheme in the embodiment of the utility model will be described clearly and completely in the following by combining the drawings in the embodiment of the utility model, obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments. Based on the embodiment in the utility model, all other embodiments obtained by those skilled in the art without creating labor belong to the scope of protection of the utility model.

[0012] Please refer toFigure 1 , Figure 1 It is the circuit diagram of the first embodiment of the utility model's boost power conversion circuit, the boost power conversion circuit includes power supply, first reactor L1, first switch tube Q1, second switch tube Q2, first diode D1, second diode D2, output upper bus capacitor C2 and output lower bus capacitor C3, the power supply, first reactor L1, first switch tube Q1 and second switch tube Q2 are sequentially connected in series to form a loop, the first diode D1, second diode D2, output upper bus capacitor C2 and output lower bus capacitor C3 are sequentially connected in series, the anode of the first diode D1 is connected with the one end of the first reactor L1 and the electric energy input end of the first switch tube Q1, the electric energy output end of the first switch tube Q1 is connected with the negative pole of the power supply and output lower bus bus- through the second switch tube Q2, the cathode of the first diode D1 is connected with the anode of the second diode D2, the cathode of the second diode D2 and the first end of the output upper bus capacitor C2 are connected with output upper bus bus+, the second end of the output upper bus capacitor C2 is connected with output lower bus bus-, the electric energy output end of the second switch tube Q2 and the negative pole of the power supply through the output lower bus capacitor C3, the boost power conversion circuit further includes flying capacitor Cfly, third diode D3, fourth diode D4 and current limiting piece, the first end of the flying capacitor Cfly is electrically connected at the series connection node of the first diode D1 and the second diode D2, the second end of the flying capacitor Cfly is electrically connected at the series connection node of the output upper bus capacitor C2 and the output lower bus capacitor C3 through the third diode D3, the anode of the third diode D3 and the second end of the flying capacitor Cfly are electrically connected at the series connection node of the first switch tube Q1 and the second switch tube Q2, the cathode of the fourth diode D4 is electrically connected at the series connection node of the first diode D1 and the second diode D2, the anode of the fourth diode D4 is electrically connected at the series connection node of the output upper bus capacitor C2 and the output lower bus capacitor C3 through the current limiting piece.

[0013] The boost power conversion circuit is electrically connected between the first diode D1 and the second diode D2 through a first end of a flying capacitor Cfly, and a second end of the flying capacitor Cfly is electrically connected between the first switch tube Q1 and the second switch tube Q2, the second end of the flying capacitor Cfly is electrically connected between the output upper bus capacitor C2 and the output lower bus capacitor C3 through a third diode D3, so that when the power supply voltage has been established and the bus voltage has not been established, the third diode D3 can clamp the voltage stress of the second switch tube Q2 to the voltage across the output lower bus capacitor C3, so as to effectively limit the voltage stress of the second switch tube Q2, thereby effectively protecting the second switch tube Q2 and avoiding overvoltage breakdown; in combination with the fourth diode D4 which is electrically connected between the first diode D1 and the second diode D2, when the bus voltage has been established and the power supply input has not been powered on, the fourth diode D4 clamps the voltage stress of the second diode D2 to the output upper bus voltage, thereby ensuring that the second diode D2 will only withstand half of the bus voltage, effectively protecting the second diode D2 and avoiding overvoltage breakdown; by setting the current limiting member, the transient current of the fourth diode D4 can be effectively limited, and the fourth diode D4 will not be damaged due to unstable flying capacitor or bus voltage fluctuation, thereby reducing the risk of damage to the circuit devices of the overall circuit during high-voltage output.

[0014] Specifically, in the first embodiment, the current limiting member is a current limiting reactor to avoid heating problems and reduce circuit loss, and in the first embodiment, the current limiting member is L2. Of course, in some embodiments, the current limiting member can be a current limiting resistor.

[0015] Preferably, the power output end of the first switch tube Q1 is connected with the power input end of the second switch tube Q2, the power output end of the second switch tube Q2 is connected with the negative electrode of the power supply and the output lower bus bus-, and the first switch tube Q1 and the second switch tube Q2 are both NMOS tubes, so that the power input end of the first switch tube Q1 is the drain of the NMOS tube, the power output end of the first switch tube Q1 is the source of the NMOS tube, the power input end of the second switch tube Q2 is the drain of the NMOS tube, and the power output end of the second switch tube Q2 is the source of the NMOS tube.

[0016] Specifically, the boost power conversion circuit further comprises a first capacitor C1 which is connected in parallel with the power supply to smooth the direct current voltage of the power supply. The first end of the first capacitor C1 is connected with the positive electrode of the power supply and one end of the first reactor L1, and the second end of the capacitor is connected with the negative electrode of the power supply, the power output end of the second switch tube Q2 and the output lower bus bus-.

[0017] Specifically, Figure 2 The second embodiment of the boost power conversion circuit of the utility model is shown, Figure 2As shown in the second embodiment, the third diode D3 is electrically connected to the series connection node of the output upper bus capacitor C2 and the output lower bus capacitor C3 through the current limiting member, so as to limit the current on the third diode D3 through the current limiting member and protect the third diode D3, and the second end of the flying capacitor Cfly is connected to the series connection node of the output upper bus capacitor C2 and the output lower bus capacitor C3 through the third diode D3 and the current limiting member.

[0018] Specifically, Figure 3 A third embodiment of the boost power conversion circuit of the utility model is shown, which is similar to the first embodiment, and will not be described here. Figure 3As shown, the boost power conversion circuit further comprises a third switch tube Q3, a fifth diode D5, a second flying capacitor Cfly2, a middle bus capacitor C4, a sixth diode D6, a seventh diode D7 and a third current limiting element, the third switch tube Q3 is electrically connected between the first switch tube Q1 and the second switch tube Q2, so that the first switch tube Q1, the third switch tube Q3 and the second switch tube Q2 are connected in series, the middle bus capacitor C4 is electrically connected between the output upper bus capacitor C2 and the output lower bus capacitor C3, so that the output upper bus capacitor C2, the middle bus capacitor C4 and the output lower bus capacitor C3 are connected in series, the fifth diode D5 is electrically connected between the second diode D2 and the output upper bus capacitor C2, so that the first diode D1, the second diode D2, the fifth diode D5, the output upper bus capacitor C2, the middle bus capacitor C4 and the output lower bus capacitor C3 are connected in series, the cathode of the second diode D2 is connected to the first end of the output upper bus capacitor C2 and the output upper bus bus+ through the fifth diode D5, the second end of the flying capacitor Cfly is electrically connected to the first end of the middle bus capacitor C4 through the third diode D3 and the current limiting element, the second end of the middle bus capacitor C4 is connected to the first end of the output lower bus capacitor C3, the second end of the output lower bus capacitor C3 is connected to the negative electrode of the power supply and the output lower bus bus-, the first end of the second flying capacitor Cfly2 is electrically connected to the series connection node of the second diode D2 and the fifth diode D5, the second end of the second flying capacitor Cfly2 is electrically connected to the series connection node of the middle bus capacitor C4 and the output lower bus capacitor C3 through the sixth diode D6, the anode of the sixth diode D6 and the second end of the second flying capacitor Cfly2 are electrically connected to the series connection node of the third switch tube Q3 and the second switch tube Q2, the cathode of the seventh diode D7 is electrically connected to the series connection node of the second diode D2 and the fifth diode D5, and the anode of the seventh diode D7 is electrically connected to the series connection node of the middle bus capacitor C4 and the output lower bus capacitor C3 through the third current limiting element.By limiting the voltage stress of the third switch tube Q3 and the second switch tube Q2 through the third diode D3 and the sixth diode D6 respectively when the power supply voltage has been established and the bus voltage has not been established, the third switch tube Q3 and the second switch tube Q2 are effectively protected, and overvoltage breakdown is avoided.

[0019] Preferably, the third switch tube Q3 is an NMOS tube.

[0020] Specifically, in the third embodiment, the third current limiting member is a current limiting reactor, so as to prevent heating problem and further reduce circuit loss, and the third current limiting member is L3.

[0021] Specifically, in the third embodiment, the sixth diode D6 is electrically connected to the series connection node of the middle bus capacitor C4 and the output lower bus capacitor C3 through the third current limiting member, so as to limit the current on the sixth diode D6 through the third current limiting member and protect the sixth diode D6, and the second end of the second flying capacitor Cfly2 is connected to the series connection node of the middle bus capacitor C4 and the output lower bus capacitor C3 through the sixth diode D6 and the third current limiting member.

[0022] Specifically, the photovoltaic inverter of the utility model comprises the boost power conversion circuit, so as to reduce the risk that the circuit device is damaged when high voltage is output.

[0023] In summary, the utility model discloses the boost power conversion circuit through the first diode and the second diode between the electric connection has the first end of flying capacitor, and the second end of flying capacitor is electrically connected between the first switch tube and the second switch tube, the second end of flying capacitor is electrically connected between output upper bus capacitor and output lower bus capacitor through the third diode, to when the bus voltage has established and the power voltage has not established, the third diode can clamp the voltage stress of second switch tube to the voltage of output lower bus capacitor both ends, can effectively limit the voltage stress of second switch tube, thereby effectively protecting second switch tube, avoid overvoltage breakdown, combine the fourth diode of cathode electric connection between the first diode and the second diode, when the bus voltage has established and the power input has not powered on, the fourth diode clamps the voltage stress of second switch tube to output upper bus voltage, thereby guaranteeing that second switch tube will only bear half bus voltage, effectively protecting second switch tube, avoid overvoltage breakdown, by setting current -limiting piece, can effectively limit the transient current of fourth diode, protect fourth diode and not damage due to flying capacitor instability or bus voltage fluctuation eventually leads its transient current too big, further reduce the risk of the circuit device of overall circuit when high -voltage output is damaged. The utility model discloses photovoltaic inverter also has the above-mentioned function.

[0024] The above is only the specific implementation of the utility model, but the protection scope of the utility model is not limited to this, any skilled person in the art can easily think of various equivalent modifications or replacements in the technical range disclosed by the utility model, and these modifications or replacements should be covered in the protection scope of the utility model. Therefore, the protection scope of the utility model should be the protection scope of the claims.

Claims

1. A boost power conversion circuit comprising a power supply, a first reactor, a first switch tube, a second switch tube, a first diode, a second diode, an output upper bus capacitor and an output lower bus capacitor, the power supply, the first reactor, the first switch tube and the second switch tube are connected in series to form a loop, the first diode, the second diode, the output upper bus capacitor and the output lower bus capacitor are connected in series, the anode of the first diode is connected with one end of the first reactor and the power input end of the first switch tube, the power output end of the first switch tube is connected with the negative pole of the power supply and the output lower bus through the second switch tube, the cathode of the first diode is connected with the anode of the second diode, the cathode of the second diode and the first end of the output upper bus capacitor are connected with the output upper bus, the second end of the output upper bus capacitor is connected with the output lower bus, the power output end of the second switch tube and the negative pole of the power supply through the output lower bus capacitor, characterized in that, The boost power conversion circuit further comprises a flying capacitor, a third diode, a fourth diode and a current limiting component, a first end of the flying capacitor is electrically connected between the first diode and the second diode, a second end of the flying capacitor is electrically connected between the output upper bus capacitor and the output lower bus capacitor through the third diode, an anode of the third diode and the second end of the flying capacitor are electrically connected between the first switch tube and the second switch tube, a cathode of the fourth diode is electrically connected between the first diode and the second diode, an anode of the fourth diode is electrically connected between the output upper bus capacitor and the output lower bus capacitor through the current limiting component.

2. The boost power conversion circuit of claim 1, wherein, The third diode is electrically connected between the output upper bus capacitor and the output lower bus capacitor through the current limiting component.

3. The boost power conversion circuit of claim 2, wherein, The boost power conversion circuit further comprises a third switch tube, a fifth diode, a second flying capacitor, a middle bus capacitor, a sixth diode, a seventh diode and a third current limiting component, the third switch tube is electrically connected between the first switch tube and the second switch tube, so that the first switch tube, the third switch tube and the second switch tube are connected in series, the middle bus capacitor is electrically connected between the output upper bus capacitor and the output lower bus capacitor, so that the output upper bus capacitor, the middle bus capacitor and the output lower bus capacitor are connected in series, the fifth diode is electrically connected between the second diode and the output upper bus capacitor, so that the first diode, the second diode, the fifth diode, the output upper bus capacitor, the middle bus capacitor and the output lower bus capacitor are connected in series, a cathode of the second diode is connected to a first end of the output upper bus capacitor and an output upper bus through the fifth diode, a second end of the flying capacitor is electrically connected to a first end of the middle bus capacitor through the third diode and the current limiting component, a second end of the middle bus capacitor is connected to a first end of the output lower bus capacitor, a second end of the output lower bus capacitor is connected to a negative pole of the power supply and an output lower bus, a first end of the second flying capacitor is electrically connected between the second diode and the fifth diode, a second end of the second flying capacitor is electrically connected between the middle bus capacitor and the output lower bus capacitor through the sixth diode, an anode of the sixth diode and the second end of the second flying capacitor are electrically connected between the third switch tube and the second switch tube, a cathode of the seventh diode is electrically connected between the second diode and the fifth diode, an anode of the seventh diode is electrically connected between the middle bus capacitor and the output lower bus capacitor through the third current limiting component.

4. The boost power conversion circuit of claim 3, wherein, The sixth diode is electrically connected between the middle bus capacitor and the output lower bus capacitor through the third current limiting component.

5. The boost power conversion circuit of claim 1, wherein, The current limiting component is a current limiting reactor or a current limiting resistor.

6. The boost power conversion circuit of claim 1, wherein, The boost power conversion circuit further comprises a first capacitor, and the first capacitor is connected in parallel with the power supply.

7. A photovoltaic inverter, characterized by The boost power conversion circuit comprises any one of claims 1-6. The boost power conversion circuit comprises any one of claims 1-6.

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