High-frequency chained micro inverter and photovoltaic power generation system

Abstract

The invention discloses a high-frequency chain type micro inverter and a photovoltaic power generation system. The high-frequency chained micro inverter comprises an inverter circuit, a voltage transformation module and a buck-boost circuit, the input end of the inverter circuit is connected with a direct-current power supply end, the output end of the inverter circuit is connected with a primary winding of the voltage transformation module, a secondary winding of the voltage transformation module is connected with the buck-boost circuit, and the output end of the buck-boost circuit serves as the output end of the high-frequency chained micro inverter; the inverter circuit is used for performing inversion according to a direct current signal provided by a direct current power supply end to form a first alternating current signal; the voltage transformation module is used for performing boost conversion according to the first alternating current signal to form a second alternating current signal; the buck-boost circuit is used for carrying out buck-boost conversion on the second AC signal to form a sinusoidal signal. The transformation ratio requirement on the transformation module can be reduced, and the efficiency of the high-frequency chain type micro inverter is improved. And moreover, the gain of the high-frequency chain type micro inverter is adjustable.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of photovoltaic power generation, and in particular to a high-frequency chain-type micro-inverter and a photovoltaic power generation system. Background Art

[0002] In the prior art, the voltage boosting capability of a high-frequency chain inverter depends on a high-ratio step-up transformer. When the ratio of the high-frequency chain inverter is too high, the step-up transformer will have high losses and high parasitic parameters, which will reduce the performance of the high-frequency chain inverter. Summary of the invention

[0003] The present invention provides a high-frequency chain-type micro-inverter and a photovoltaic power generation system to improve the performance of the high-frequency chain-type inverter.

[0004] In a first aspect, an embodiment of the present invention provides a high-frequency chain-link micro-inverter, including an inverter circuit, a voltage conversion module, and a buck-boost circuit;

[0005] The input end of the inverter circuit is connected to the DC power supply end, the output end of the inverter circuit is connected to the primary winding of the transformer module, the secondary winding of the transformer module is connected to the buck-boost circuit, and the output end of the buck-boost circuit serves as the output end of the high-frequency chain micro-inverter; the inverter circuit is used to invert the DC signal provided by the DC power supply end to form a first AC signal; the transformer module is used to perform a boost conversion according to the first AC signal to form a second AC signal; the buck-boost circuit is used to perform a buck-boost conversion on the second AC signal to form a sinusoidal signal.

[0006] Optionally, the step-up / step-down circuit includes at least one buck-boost circuit;

[0007] The first end of the buck-boost circuit is connected to the first end of the secondary winding of the transformer module, the output end of the buck-boost circuit serves as the output end of the high-frequency chain micro-inverter, and the second end of the buck-boost circuit is connected to the second end of the secondary winding of the transformer module; the buck-boost circuit is used to perform step-up and step-down conversion on the half-cycle signal of the second AC signal.

[0008] Optionally, the buck-boost circuit includes a first switch unit, a second switch unit, a first capacitor and a first inductor;

[0009] The first end of the first switch unit is connected to the first end of the secondary winding of the transformer module, the second end of the first switch unit is connected to the first end of the first inductor and the first end of the second switch unit, the second end of the second switch unit is connected to the first pole of the first capacitor and serves as the output end of the high-frequency chain micro-inverter, the second end of the first inductor and the second pole of the first capacitor are connected to the second end of the secondary winding of the transformer module; the first switch unit and the second switch unit are turned on in time-sharing manner.

[0010] Optionally, the first switch unit includes a first secondary switch tube and a second secondary switch tube, and the second switch unit includes a third secondary switch tube and a fourth secondary switch tube;

[0011] The first electrode of the first secondary switch tube is connected to the first end of the secondary winding of the transformer module, the second electrode of the first secondary switch tube is connected to the second electrode of the second secondary switch tube, the first electrode of the second secondary switch tube is connected to the first electrode of the third secondary switch tube and the first end of the first inductor, the second electrode of the third secondary switch tube is connected to the second electrode of the fourth secondary switch tube, and the first electrode of the fourth secondary switch tube is connected to the first electrode of the first capacitor; the first secondary switch tube and the second secondary switch tube are turned on or off synchronously, and the third secondary switch tube and the fourth secondary switch tube are turned on or off synchronously.

[0012] Optionally, when the step-up and step-down circuit includes two buck-boost circuits, the two buck-boost circuits are used to perform step-up and step-down conversion on at least one half-cycle signal of the second AC signal.

[0013] Optionally, the secondary winding includes a first secondary winding and a second secondary winding;

[0014] The first ends of the two buck-boost circuits are respectively connected to the first end of the first secondary winding and the first end of the second secondary winding, the second end of the first secondary winding and the second end of the second secondary winding are grounded, and the second end of each buck-boost circuit is connected to the second end of the first secondary winding; wherein the first end of the first secondary winding and the first end of the second secondary winding are like-named ends.

[0015] Optionally, the inverter circuit includes a first primary switch tube, a second primary switch tube, a second capacitor and a third capacitor;

[0016] The first pole of the first primary switch tube and the first pole of the second capacitor are connected to the positive end of the DC power supply end, the second pole of the first primary switch tube is connected to the first pole of the second primary switch tube and is connected to the second end of the primary winding, the second pole of the second capacitor is connected to the first pole of the third capacitor and is connected to the first end of the primary winding, and the second pole of the third capacitor and the second pole of the second primary switch tube are connected to the negative end of the DC power supply end.

[0017] Optionally, the inverter circuit includes a third primary switch tube, a fourth primary switch tube, a fifth primary switch tube and a sixth primary switch tube;

[0018] The first pole of the third primary switch tube and the first pole of the fourth primary switch tube are connected to the positive end of the DC power supply end, the second pole of the third primary switch tube is connected to the first pole of the fifth primary switch tube and is connected to the first end of the primary winding, the second pole of the fourth primary switch tube is connected to the first pole of the sixth primary switch tube and is connected to the second end of the primary winding, and the second pole of the fifth primary switch tube and the second pole of the sixth primary switch tube are connected to the negative end of the DC power supply end.

[0019] Optionally, the inverter circuit includes a seventh primary switch tube and an eighth primary switch tube;

[0020] The first pole of the seventh primary switch tube and the first pole of the eighth primary switch tube are connected to the negative end of the DC power supply end, the second pole of the seventh primary switch tube is connected to the first end of the primary winding, the second pole of the eighth primary switch tube is connected to the second end of the primary winding, and the center tap of the primary winding is connected to the positive end of the DC power supply end.

[0021] In a second aspect, an embodiment of the present invention further provides a photovoltaic power generation system, comprising the high-frequency chain micro-inverter described in the first aspect.

[0022] The technical solution of the embodiment of the present invention can increase the gain of the high-frequency chain micro-inverter by setting a buck-boost circuit to perform buck-boost conversion on the second AC signal output by the transformer module. When the gain requirement of the high-frequency chain micro-inverter remains unchanged, the transformation ratio requirement of the transformer module can be reduced, thereby reducing the efficiency loss caused by the parasitic parameters of the transformer module and increasing the efficiency of the high-frequency chain micro-inverter. Moreover, the voltage transformation ratio of the high-frequency chain micro-inverter can be adjusted by adjusting the duty cycle of the energy storage switch tube, thereby achieving adjustable gain of the high-frequency chain micro-inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A structural schematic diagram of a high-frequency chain inverter provided for related technology;

[0024] Figure 2 The equivalent voltage output schematic diagram of the high-frequency chain-type micro-inverter provided for the related technology;

[0025] Figure 3 A schematic structural diagram of a high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of the principle of a buck-boost circuit provided by an embodiment of the present invention;

[0027] Figure 5 for Figure 4 The equivalent voltage output schematic diagram of the buck-boost circuit provided;

[0028] Figure 6 A schematic diagram of the structure of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0029] Figure 7 A schematic diagram of the structure of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0030] Figure 8 A schematic diagram of the structure of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0031] Fig. 9 A schematic diagram of the structure of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0032] Fig.10 A schematic diagram of the structure of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0033] Fig.11 A schematic diagram of the structure of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention;

[0034] Fig.12 A schematic structural diagram of another high-frequency chain-link micro-inverter provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0036] Figure 1 A schematic diagram of a high-frequency chain inverter provided for related technology, Figure 2 The equivalent voltage output principle diagram of the high-frequency chain micro inverter provided for the related technology. Figure 1 and Figure 2 As shown, the DC power provided by the DC power supply end is output to the primary winding of the transformer after passing through the primary full-bridge circuit, and then is boosted by the transformer and outputs a sinusoidal signal after passing through the secondary conversion circuit to achieve DC inversion. In the related art, the secondary conversion circuit is an AC buck circuit composed of back-to-back switch tubes and an output filter inductor. That is, a half-bridge secondary conversion circuit 101 is composed of a first switch tube Q1 and a second switch tube Q2 connected back to back, a switch tube connected back to back with a third switch tube Q3 and a fourth switch tube Q4, and an output filter inductor, and then two half-bridge secondary conversion circuits 101 form an AC buck circuit. Taking the half-bridge secondary conversion circuit 101 as an example, D Q1 is the conduction duty ratio of the first switch tube Q1 and the second switch tube Q2 in the cycle of the half-bridge secondary side conversion circuit 101. sw1 is a high-frequency switching cycle. For each half-bridge secondary side conversion circuit 101, only half of the high-frequency square wave can be used to complete the split-phase AC output. Because:

[0037] 0≤D Q1 ≤0.5T sw1 ,

[0038] but:

[0039] 0≤v o1 ≤0.5n1V in1 ,

[0040] 0≤v o2 ≤0.4n1V in1 ,

[0041] v o1m =D Q1 n1V in1 ;

[0042] Among them, V in1 is the DC voltage provided by the DC power supply, n1 is the transformation ratio of the transformer, v an1 is the voltage of the node a1 between the first switch tube Q1 and the third switch tube Q3 to the ground, which is n1V in1 .v s1 is the voltage across the secondary winding, with an amplitude of n1V in1 AC square wave voltage. v o1 is the output voltage of the first phase output terminal o1 of the high-frequency chain micro-inverter, v o2 is the output voltage of the second phase output terminal o2 of the high-frequency chain micro-inverter, v o1m It is the output voltage between the first phase output terminal o1 and the second phase output terminal o2 of the high frequency chain micro inverter.

[0043] From the above analysis, it can be seen that the output voltage of the high-frequency chain micro-inverter is less than or equal to half of the output voltage of the secondary winding of the transformer. When the input voltage of the high-frequency chain micro-inverter is relatively low and the output voltage is required to be relatively high, the transformer needs to have a higher transformation ratio, resulting in high losses and high parasitic parameters in the step-up transformer, which reduces the performance of the high-frequency chain inverter.

[0044] In order to solve the above technical problems, an embodiment of the present invention provides a high-frequency chain-link micro-inverter. Figure 3 The structure diagram of a high-frequency chain-type micro-inverter provided by an embodiment of the present invention is shown in FIG. Figure 3 As shown, the high-frequency chain micro inverter includes an inverter circuit 10, a transformer module 20 and a buck-boost circuit 30; the input end of the inverter circuit 10 is connected to the DC power supply end VIN, and the output end of the inverter circuit 10 is connected to the primary winding N of the transformer module 20. p Connect the secondary winding N of the transformer module 20 s It is connected to the buck-boost circuit 30, and the output end of the buck-boost circuit 30 serves as the output end VOUT of the high-frequency chain micro-inverter; the inverter circuit 10 is used to invert the DC signal provided by the DC power supply terminal VIN to form a first AC signal; the transformer module 20 is used to perform a boost conversion according to the first AC signal to form a second AC signal; the buck-boost circuit 30 is used to perform a buck-boost conversion on the second AC signal to form a sinusoidal signal.

[0045] Specifically, the high-frequency chain micro-inverter can be applied to a photovoltaic power generation system. The DC power supply terminal VIN of the high-frequency chain micro-inverter can be connected to the output terminal of the photovoltaic panel, so that the input signal provided by the signal input terminal VIN is direct current. The inverter circuit 10 can invert the DC signal provided by the DC power supply terminal VIN to form a first AC signal. At this time, the first AC signal can be an AC square wave signal. The transformer module 20 may include a transformer, and the transformer performs a step-up conversion on the first AC signal to form a second AC signal. At this time, the voltage ratio of the second AC signal to the first AC signal is the transformation ratio of the transformer. Then the step-up and step-down circuit 30 performs a step-up and step-down conversion on the second AC signal, and performs a filtering effect, so that the step-up and step-down circuit 30 outputs a sinusoidal signal, thereby realizing the inversion of the DC signal provided by the DC power supply terminal VIN. When the step-up and step-down circuit 30 performs a step-up and step-down conversion on the second AC signal, the step-up and step-down circuit 30 can perform a step-up and step-down conversion on the signal of the positive half cycle and / or the negative half cycle of the second AC signal. When the buck-boost circuit 30 performs buck-boost conversion on the half-cycle signal of the second AC signal, the switching period of the buck-boost circuit 30 is equal to the period of the second AC signal. The buck-boost circuit 30 includes an energy storage phase and a discharge phase. By adjusting the ratio of the energy storage phase to the switching period in the buck-boost circuit 30, the transformation ratio of the buck-boost circuit 30 can be adjusted, thereby adjusting the transformation ratio of the sinusoidal signal to the second AC signal.

[0046] For example, Figure 4 A schematic diagram of a buck-boost circuit according to an embodiment of the present invention is provided. Figure 5 for Figure 4 The equivalent voltage output schematic diagram of the buck-boost circuit is provided. Figure 4 and Figure 5 As shown, the step-up / down voltage circuit 30 may include a buck-boost circuit. The buck-boost circuit includes an energy storage switch tube Q 1,2 , discharge switch tube Q 3,4 , filter inductor L1 and filter capacitor C1, energy storage switch tube Q 1,2 The first end of the transformer module 30 is connected to the secondary winding N s The first end is connected to the energy storage switch tube Q 1,2 The second end of the discharge switch tube Q 3,4 The first end of the discharge switch tube Q is connected to the first end of the filter inductor L1. 3,4 The second end of the filter inductor L1 and the second end of the filter capacitor C1 are connected to the first electrode of the filter capacitor C1 and serve as the output end VOUT of the high-frequency chain micro-inverter. The second end of the filter inductor L1 and the second electrode of the filter capacitor C1 are connected to the secondary winding N of the transformer module 30. s In the energy storage stage, the energy storage switch tube Q 1,2 Turn on, discharge switch tube Q 3,4 The filter inductor L1 is turned off and charged. The voltage across the filter inductor L1 is equal to the secondary winding N of the transformer module 30. s In the discharge phase, the energy storage switch tube Q 1,2 Turn off, discharge switch tube Q 3,4 The filter inductor L1 is turned on through the discharge switch tube Q 3,4 Discharge to supply power to the output terminal VOUT of the high-frequency chain micro-inverter. 1,2 And the discharge switch tube Q 3,4 The switching period of the energy storage switch tube Q is equal to the period of the second AC signal. The second AC signal is an AC signal, which makes the energy storage switch tube Q 1,2 The conduction duty cycle is less than or equal to the half cycle of the second AC signal. sw When the switching cycle is high frequency, the energy storage switch tube Q 1,2 Duty cycle D Q The range is:

[0047] 0≤D Q ≤0.5T sw ,

[0048] The voltage v at the output end VOUT of the frequency chain micro inverter is out for:

[0049] 0<vout ≤nV in ;

[0050]

[0051] Among them, V in is the DC voltage provided by the DC power supply terminal VIN, and n is the transformation ratio of the transformer module 20. an Q is the energy storage switch tube 1,2 With the discharge switch tube Q 3,4 The voltage between node a and ground is nV in .v s N is the secondary winding s The voltage across the two ends is nV in AC square wave voltage, v out is the output voltage of the output terminal VOUT of the high-frequency chain micro-inverter.

[0052] At this time, by adjusting the energy storage switch tube Q 1,2 Duty cycle D Q , the maximum voltage of the output terminal VOUT of the high-frequency chain micro-inverter can be made to be the secondary winding N of the transformer module 20 s The output voltage can increase the gain of the high-frequency chain micro-inverter on the basis of the unchanged transformation ratio of the transformer module 20 compared with the related art. When the gain requirement of the high-frequency chain micro-inverter remains unchanged, the transformation ratio requirement of the transformer module 20 can be reduced, thereby reducing the efficiency loss caused by the parasitic parameters of the transformer module 20 and increasing the efficiency of the high-frequency chain micro-inverter. In addition, the energy storage switch tube Q can be adjusted to 1,2 Duty cycle D Q The voltage transformation ratio of the high-frequency chain-type micro-inverter is adjusted to achieve adjustable gain of the high-frequency chain-type micro-inverter.

[0053] The technical solution of this embodiment can increase the gain of the high-frequency chain micro-inverter by setting a buck-boost circuit to perform buck-boost conversion on the second AC signal output by the transformer module. When the gain requirement of the high-frequency chain micro-inverter remains unchanged, the transformation ratio requirement of the transformer module can be reduced, thereby reducing the efficiency loss caused by the parasitic parameters of the transformer module and increasing the efficiency of the high-frequency chain micro-inverter. Moreover, the voltage transformation ratio of the high-frequency chain micro-inverter can be adjusted by adjusting the duty cycle of the energy storage switch tube, thereby achieving adjustable gain of the high-frequency chain micro-inverter.

[0054] Figure 6 A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Figure 6As shown, the step-up / down voltage circuit 30 includes at least one buck-boost circuit; a first end of the buck-boost circuit is connected to the secondary winding N of the transformer module 20. S The output end of the buck-boost circuit is used as the output end VOUT of the high-frequency chain micro-inverter, and the second end of the buck-boost circuit is connected to the secondary winding N of the transformer module 20. S The buck-boost circuit is used to perform step-up and step-down conversion on the half-cycle signal of the second AC signal.

[0055] Specifically, Figure 6 The buck-boost circuit 30 includes a buck-boost circuit, and the transformer module 20 is a double-winding transformer. The first end of the buck-boost circuit is connected to the secondary winding N of the transformer module 20. S The first end of the buck-boost circuit is connected to the secondary winding N of the transformer module 20. S The second end of the power supply is connected. When the second AC signal is in the positive half cycle, the buck-boost circuit can be controlled to be in the energy storage stage, so that the buck-boost circuit stores the positive half cycle electric energy of the second AC signal. When the second AC signal is in the negative half cycle, the buck-boost circuit can be controlled to be in the discharge stage, so that the buck-boost circuit discharges the stored electric energy. At this time, the ratio of the discharge voltage of the buck-boost circuit to the voltage of the positive half cycle of the second AC signal is adjusted according to the duty cycle of the energy storage stage, so that the ratio range of the output voltage of the high-frequency chain micro-inverter to the voltage of the positive half cycle of the second AC signal can be extended to nV in , so that the gain of the high-frequency chain micro-inverter can be increased through the buck-boost circuit, and the gain of the high-frequency chain micro-inverter can be adjusted.

[0056] Alternatively, when the second AC signal is in the negative half cycle, the buck-boost circuit can be controlled to be in the energy storage stage, so that the buck-boost circuit stores the negative half cycle electric energy of the second AC signal. When the second AC signal is in the positive half cycle, the buck-boost circuit can be controlled to be in the discharge stage, so that the buck-boost circuit discharges the stored electric energy. At this time, the ratio of the discharge voltage of the buck-boost circuit to the voltage of the negative half cycle of the second AC signal is adjusted according to the duty cycle of the energy storage stage, so that the ratio range of the output voltage of the high-frequency chain micro inverter to the voltage of the negative half cycle of the second AC signal can be extended to nV. in , and the gain of the high-frequency chain micro-inverter can also be increased, thereby achieving adjustable gain of the high-frequency chain micro-inverter.

[0057] Continue to refer Figure 6 The buck-boost circuit includes a first switch unit 301, a second switch unit 302, a first capacitor C f and the first inductor L f The first end of the first switch unit 301 and the secondary winding N of the transformer module 20 S The first end of the first switch unit 301 is connected to the first inductor L f The first end of the second switch unit 302 is connected to the first end of the second switch unit 302, and the second end of the second switch unit 302 is connected to the first capacitor C f The first pole is connected and serves as the output terminal VOUT of the high-frequency chain micro-inverter. The first inductor L f The second terminal and the first capacitor C f The second pole and the secondary winding N of the transformer module 20 S The first switch unit 301 and the second switch unit 302 are turned on in a time-sharing manner.

[0058] Specifically, Figure 6 As shown, when the first switch unit 301 is turned on and the second switch unit 302 is turned off, the first switch unit 301 and the first inductor L f and the secondary winding N S The energy storage circuit is formed so that the first inductor L f Can store the secondary winding N S When the first switch unit 301 is turned off and the second switch unit 302 is turned on, the second switch unit 302 and the first inductor L f and the first capacitor C f The discharge circuit is formed so that the first inductor L f The output terminal VOUT of the high-frequency chain micro-inverter provides power. The ratio of the on-time of the first switch unit 301 to the duty cycle of the buck-boost circuit is the duty cycle of the first switch unit 301. Since the second AC signal is an AC signal, the duty cycle of the first switch unit 301 is less than or equal to 0.5. f The discharge voltage v out The range is less than or equal to the secondary winding N S Provided voltage nV in , thus the output voltage of the high-frequency chain-type micro-inverter can be increased exponentially compared with the related art, and the transformation ratio requirement of the transformer module 20 can be reduced, thereby reducing the efficiency loss caused by the parasitic parameters of the transformer module 20, and increasing the efficiency of the high-frequency chain-type micro-inverter. At the same time, the gain of the high-frequency chain-type micro-inverter can be adjusted by adjusting the duty cycle of the first switch unit 301, so that the gain of the high-frequency chain-type micro-inverter is adjustable.

[0059] Continue to refer Figure 6 The first switch unit 301 includes a first secondary switch tube Q1 and a second secondary switch tube Q2, and the second switch unit 302 includes a third secondary switch tube Q3 and a fourth secondary switch tube Q4; the first electrode of the first secondary switch tube Q1 is connected to the secondary winding N of the transformer module 20. S The first end of the first secondary switch tube Q1 is connected to the second end of the second secondary switch tube Q2, the first end of the second secondary switch tube Q2 is connected to the first end of the third secondary switch tube Q3 and the first inductor L f The first end of the third secondary switch tube Q3 is connected to the second end of the fourth secondary switch tube Q4, and the first end of the fourth secondary switch tube Q4 is connected to the first capacitor C f the first secondary switch tube Q1 and the second secondary switch tube Q2 are turned on or off synchronously, and the third secondary switch tube Q3 and the fourth secondary switch tube Q4 are turned on or off synchronously.

[0060] Specifically, the first secondary switch tube Q1 and the second secondary switch tube Q2 can be connected in series back-to-back, and the third secondary switch tube Q3 and the fourth secondary switch tube Q4 can also be connected in series back-to-back. By setting the first secondary switch tube Q1 and the second secondary switch tube Q2 to be connected back-to-back, and the third secondary switch tube Q3 and the fourth secondary switch tube Q4 to be connected back-to-back, the high-frequency chain micro-inverter has reactive power support capability. At the same time, it is conducive to realizing the commutation of the buck-boost circuit, optimizing the current path of the buck-boost circuit, and improving the efficiency of the buck-boost circuit.

[0061] Continue to refer Figure 6 The inverter circuit 10 includes a first primary switch tube T1, a second primary switch tube T2, a second capacitor C2 and a third capacitor C3; the first electrode of the first primary switch tube T1 and the first electrode of the second capacitor C2 are connected to the positive terminal + of the DC power supply terminal VIN, the second electrode of the first primary switch tube T1 is connected to the first electrode of the second primary switch tube T2, and is connected to the primary winding N p The second terminal M2 of the second capacitor C2 is connected to the first terminal of the third capacitor C3, and the second terminal M3 of the second capacitor C2 is connected to the first terminal of the third capacitor C3, and the first terminal M4 of the primary winding N p The first end M1 is connected to the first end M2, the second electrode of the third capacitor C3 and the second electrode of the second primary switch tube T2 are connected to the negative end - of the DC power supply end VIN.

[0062] Specifically, Figure 6 The inverter circuit 10 is exemplarily shown as a half-bridge inverter circuit. When the first primary switch tube T1 is turned on and the second primary switch tube T2 is turned off, the voltage provided by the DC power supply terminal VIN is supplied from the positive terminal + of the DC power supply terminal VIN through the first primary switch tube T1 and then from the primary winding N p The second end M2 flows to the primary winding Np The first terminal M1 of the primary winding N is connected to the first electrode of the third capacitor C3, and then transmitted to the negative terminal - of the DC power supply terminal VIN through the third capacitor C3. p The voltage of the second terminal M2 is positive and the voltage of the first terminal M1 is negative. When the first primary switch tube T1 is turned off and the second primary switch tube T2 is turned on, the voltage of the second electrode of the second capacitor C2 is generated by the primary winding N p The first end M1 flows to the primary winding N p The second terminal M2 of the primary winding is transmitted to the negative terminal - of the DC power supply terminal VIN through the second primary switch tube T2. p The voltage of the first terminal M1 is positive and the voltage of the second terminal M2 is negative, thereby realizing the inversion of the DC signal provided by the DC power supply terminal VIN.

[0063] Figure 7 A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Figure 7 As shown, the inverter circuit 10 includes a third primary switch tube T3, a fourth primary switch tube T4, a fifth primary switch tube T5 and a sixth primary switch tube T6; the first electrode of the third primary switch tube T3 and the first electrode of the fourth primary switch tube T4 are connected to the positive terminal + of the DC power supply terminal VIN, the second electrode of the third primary switch tube T3 is connected to the first electrode of the fifth primary switch tube T5, and is connected to the primary winding N p The first end M1 of the fourth primary switch tube T4 is connected to the first end M2 of the sixth primary switch tube T6, and the second end M2 of the fourth primary switch tube T4 is connected to the first end M1 of the sixth primary switch tube T6, and the first end M2 of the sixth primary switch tube T6 is connected to the first end M2 of the primary winding N p The second end M2 of the first primary switch tube T5 is connected to the negative end - of the DC power supply terminal VIN, and the second electrode of the fifth primary switch tube T5 and the second electrode of the sixth primary switch tube T6 are connected to the negative end - of the DC power supply terminal VIN.

[0064] Specifically, Figure 7 The inverter circuit 10 is exemplarily shown as a full-bridge inverter circuit. When the third primary switch tube T3 and the sixth primary switch tube T6 are turned on, and the fourth primary switch tube T4 and the fifth primary switch tube T5 are turned off, the voltage provided by the DC power supply terminal VIN is supplied from the positive terminal + of the DC power supply terminal VIN through the third primary switch tube T3 and then from the primary winding N p The first end M1 flows to the primary winding N p The second terminal M2 of the primary winding is transmitted to the negative terminal - of the DC power supply terminal VIN through the sixth primary switch tube T6. p The voltage of the first terminal M1 is positive and the second terminal M2 is negative. When the third primary switch tube T3 and the sixth primary switch tube T6 are turned off, and the fourth primary switch tube T4 and the fifth primary switch tube T5 are turned on, the voltage provided by the DC power supply terminal VIN is supplied by the positive terminal + of the DC power supply terminal VIN through the fourth primary switch tube T4 and then by the primary winding N p The second end M2 flows to the primary winding Np The first terminal M1 of the primary winding is transmitted to the negative terminal - of the DC power supply terminal VIN through the fifth primary switch tube T5. p The voltage of the second terminal M2 is positive and the voltage of the first terminal M1 is negative, thereby realizing the inversion of the DC signal provided by the DC power supply terminal VIN.

[0065] Figure 8 A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Figure 8 As shown, the inverter circuit includes a seventh primary switch tube T7 and an eighth primary switch tube T8; the first electrode of the seventh primary switch tube T7 and the first electrode of the eighth primary switch tube T8 are connected to the negative terminal - of the DC power supply terminal VIN, and the second electrode of the seventh primary switch tube T7 is connected to the primary winding N p The first end M1 of the eighth primary switch tube T8 is connected to the primary winding N p The voltage of the second terminal M2 is connected to the primary winding N p The center tap M0 is connected to the positive terminal + of the DC power supply terminal VIN.

[0066] Specifically, Figure 8 The inverter circuit 10 is exemplarily shown as a push-pull inverter circuit. When the seventh primary switch tube T7 is turned on and the eighth primary switch tube T8 is turned off, the voltage provided by the DC power supply terminal VIN is supplied from the positive terminal + of the DC power supply terminal VIN through the primary winding N p The central tap M0 of the primary winding N is connected to the first terminal M1, and is transmitted to the negative terminal - of the DC power supply terminal VIN through the seventh primary switch tube T7. p The voltage of the center tap M0 is positive and the first terminal M1 is negative. When the seventh primary switch tube T7 is turned off and the eighth primary switch tube T8 is turned on, the voltage provided by the DC power supply terminal VIN is from the positive terminal + of the DC power supply terminal VIN through the primary winding N p The central tap M0 to the second end M2 is transmitted to the negative end - of the DC power supply end VIN through the eighth primary switch tube T8. p The voltage of the center tap M0 is positive, and the second terminal M2 is negative. Thus, the inversion of the DC signal provided by the DC power supply terminal VIN is achieved.

[0067] It should be noted that Figures 6 to 8 The inverter circuit 10 is merely an example of some circuit types. In other embodiments, the inverter circuit 10 may be any high-frequency AC square wave generator. In addition, the inverter circuit 10 may also include other types of circuits. For example, the inverter circuit 10 may include at least two stages of circuits, and different stages of circuits may include a buck-boost circuit and an inverter circuit. Different stages of circuits may share components, which is not limited here.

[0068] Fig. 9 A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Fig. 9 As shown, the buck-boost circuit 30 may further include two buck-boost circuits. The two buck-boost circuits are used to perform buck-boost conversion on at least one half-cycle signal of the second AC signal.

[0069] Specifically, Fig. 9 As shown, when the buck-boost circuit 30 includes two buck-boost circuits, the two buck-boost circuits can be connected in phase. That is, the connection mode of each buck-boost circuit is the same, and the output end of each buck-boost circuit is respectively used as the single-phase output end of the high-frequency chain micro-inverter. When the single-phase output end of the high-frequency chain micro-inverter is connected to the load, different single-phase output ends can be respectively connected to different or the same loads to supply power to the load. Moreover, the single-phase output end of the high-frequency chain micro-inverter can be connected to the power grid to realize the grid-connected operation of the high-frequency chain micro-inverter. The second AC signal is an AC signal. During the operation of the buck-boost circuit 30, a buck-boost circuit can be controlled to perform a buck-boost conversion on the second AC signal in the positive half cycle of the second AC signal, and another buck-boost circuit can be controlled to perform a buck-boost conversion on the second AC signal in the negative half cycle of the second AC signal, thereby improving the utilization rate of the second AC signal, and thus improving the efficiency of the high-frequency chain micro-inverter.

[0070] For example, Fig. 9 As shown, the two buck-boost circuits are respectively a first buck-boost circuit 31 and a second buck-boost circuit 32. The first buck-boost circuit 31 includes a first first switch unit 311, a first second switch unit 312, a first first inductor L f1 and the first capacitor C f1 The first first switch unit 311 includes a first first secondary switch tube Q11 and a first second secondary switch tube Q21, and the second second switch unit 312 includes a first third secondary switch tube Q31 and a first fourth secondary switch tube Q41; the specific connection method is the same as that of a buck-boost circuit, and the first first capacitor C f1 The first pole of is used as the first single-phase output terminal VOUT1 of the high-frequency chain micro-inverter. The second buck-boost circuit 32 includes a second first switch unit 321, a second second switch unit 322, a second first inductor L f2 and the second first capacitor C f2The second first switch unit 321 includes a second first secondary switch tube Q12 and a second second secondary switch tube Q22, and the second second switch unit 312 includes a second third secondary switch tube Q32 and a second fourth secondary switch tube Q42; the specific connection method is the same as that of a buck-boost circuit, and the second first capacitor C f2 The first pole of is used as the second single-phase output terminal VOUT2 of the high-frequency chain micro-inverter. During operation, the first first secondary switch tube Q11 and the first second secondary switch tube Q21, as well as the second third secondary switch tube Q32 and the second fourth secondary switch tube Q42 can be controlled to be turned on, and the first third secondary switch tube Q31 and the first fourth secondary switch tube Q41, as well as the second first secondary switch tube Q12 and the second second secondary switch tube Q22 can be turned off during the positive half cycle of the second AC signal. At this time, the first first inductor L in the first buck-boost circuit 31 f1 The second first inductor L in the second buck-boost circuit 31 stores the electrical energy of the positive half cycle of the second AC signal. f2 Discharge is performed through the second third secondary switch tube Q32 and the second fourth secondary switch tube Q42. During the negative half cycle of the second AC signal, the first first secondary switch tube Q11 and the first second secondary switch tube Q21, as well as the second third secondary switch tube Q32 and the second fourth secondary switch tube Q42 can be turned off, and the first third secondary switch tube Q31 and the first fourth secondary switch tube Q41, as well as the second first secondary switch tube Q12 and the second second secondary switch tube Q22 can be turned on. At this time, the second first inductor L in the second buck-boost circuit 31 f2 The first inductor L in the first buck-boost circuit 31 stores the electric energy of the negative half cycle of the second AC signal. f1 Discharging is performed through the first third secondary switch tube Q31 and the first fourth secondary switch tube Q41, so that the full cycle signal of the second AC signal can be buck-boosted, thereby improving the utilization rate of the second AC signal and further improving the efficiency of the high-frequency chain-type micro-inverter.

[0071] It should be noted that Fig. 9 The inverter circuit 10 is exemplarily shown as a half-bridge inverter circuit. In other embodiments, the inverter circuit 10 can also be a full-bridge inverter circuit and a push-pull inverter circuit. Fig.10 A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Fig.10 As shown, the inverter circuit 10 and Figure 7 The inverter circuits 10 provided are the same, and are all full-bridge inverter circuits. Fig.11A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Fig.11 As shown, the inverter circuit 10 and Figure 8 The inverter circuits 10 provided are the same, and are all push-pull inverter circuits.

[0072] In some embodiments, Fig.12 A schematic diagram of the structure of another high-frequency chain-type micro-inverter provided by an embodiment of the present invention. Fig.12 As shown, the secondary winding N S Including the first secondary winding N S1 and the second secondary winding N S2 ; The first terminals of the two buck-boost circuits are connected to the first secondary winding N S1 The first end and the second secondary winding N S2 The first end of the first secondary winding N S1 The second end of the second secondary winding N S2 The second end of each buck-boost circuit is connected to the first secondary winding N. S1 The second end of the first secondary winding N S1 The first end and the second secondary winding N S2 The first end of the same name.

[0073] Specifically, the transformer module 20 may be a single three-winding high-frequency transformer, the primary side of the transformer having a single primary winding N p , the secondary side of the transformer has a first secondary winding N s1 and the second secondary winding N S2 , the first end of the first buck-boost circuit 31 is connected to the first secondary winding N S1 The first end of the second buck-boost circuit 32 is connected to the second secondary winding N S2 The first end of the first buck-boost circuit 31 and the second end of the second buck-boost circuit 32 are connected to the ground n. At this time, by controlling the working state of the two buck-boost circuits, the step-up and step-down conversion of the second AC signal is realized, so that the two buck-boost circuits output in phase. The control of the working state of the two buck-boost circuits is Figures 9 to 11 The control process is similar and will not be described here.

[0074] In some embodiments, a transformer module may also be provided including a first transformer and a second transformer, the inverter circuit being connected to the primary winding of the first transformer and the primary winding of the second transformer, the secondary winding of the first transformer and the secondary winding of the second transformer being connected to two buck-boost circuits respectively, and the step-up and step-down conversion of the second AC signal may also be achieved and then the phase-splitting output may be achieved.

[0075] An embodiment of the present invention further provides a photovoltaic power generation system. The photovoltaic power generation system includes the high-frequency chain-type micro-inverter provided by any embodiment of the present invention. Since the photovoltaic power generation system includes the high-frequency chain-type micro-inverter provided by any embodiment of the present invention, it has the same beneficial effects as the high-frequency chain-type micro-inverter provided by any embodiment of the present invention, which will not be described in detail here.

[0076] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A high frequency chain micro inverter, characterized in that: It includes an inverter circuit, a voltage conversion module and a step-up and step-down circuit; The input end of the inverter circuit is connected to the DC power supply end, the output end of the inverter circuit is connected to the primary winding of the transformer module, the secondary winding of the transformer module is connected to the buck-boost circuit, and the output end of the buck-boost circuit serves as the output end of the high-frequency chain micro-inverter; the inverter circuit is used to invert the DC signal provided by the DC power supply end to form a first AC signal; the transformer module is used to perform a boost conversion according to the first AC signal to form a second AC signal; the buck-boost circuit is used to perform a buck-boost conversion on the second AC signal to form a sinusoidal signal.

2. The high-frequency chain-link micro-inverter according to claim 1, characterized in that: The step-up / down voltage circuit includes at least one buck-boost circuit; The first end of the buck-boost circuit is connected to the first end of the secondary winding of the transformer module, the output end of the buck-boost circuit serves as the output end of the high-frequency chain micro-inverter, and the second end of the buck-boost circuit is connected to the second end of the secondary winding of the transformer module; the buck-boost circuit is used to perform step-up and step-down conversion on the half-cycle signal of the second AC signal.

3. The high frequency chain micro inverter according to claim 2, characterized in that: The buck-boost circuit includes a first switch unit, a second switch unit, a first capacitor and a first inductor; The first end of the first switch unit is connected to the first end of the secondary winding of the transformer module, the second end of the first switch unit is connected to the first end of the first inductor and the first end of the second switch unit, the second end of the second switch unit is connected to the first pole of the first capacitor and serves as the output end of the high-frequency chain micro-inverter, the second end of the first inductor and the second pole of the first capacitor are connected to the second end of the secondary winding of the transformer module; the first switch unit and the second switch unit are turned on in time-sharing manner.

4. The high-frequency chain-link micro-inverter according to claim 3, characterized in that: The first switch unit includes a first secondary switch tube and a second secondary switch tube, and the second switch unit includes a third secondary switch tube and a fourth secondary switch tube; The first electrode of the first secondary switch tube is connected to the first end of the secondary winding of the transformer module, the second electrode of the first secondary switch tube is connected to the second electrode of the second secondary switch tube, the first electrode of the second secondary switch tube is connected to the first electrode of the third secondary switch tube and the first end of the first inductor, the second electrode of the third secondary switch tube is connected to the second electrode of the fourth secondary switch tube, and the first electrode of the fourth secondary switch tube is connected to the first electrode of the first capacitor; the first secondary switch tube and the second secondary switch tube are turned on or off synchronously, and the third secondary switch tube and the fourth secondary switch tube are turned on or off synchronously.

5. The high frequency chain micro inverter according to any one of claims 2 to 4, characterized in that: When the step-up and step-down circuit includes two buck-boost circuits, the two buck-boost circuits are used to perform step-up and step-down conversion on at least one half-cycle signal of the second AC signal.

6. The high frequency chain micro inverter according to claim 5, characterized in that: The secondary winding comprises a first secondary winding and a second secondary winding; The first ends of the two buck-boost circuits are respectively connected to the first end of the first secondary winding and the first end of the second secondary winding, the second end of the first secondary winding and the second end of the second secondary winding are grounded, and the second end of each buck-boost circuit is connected to the second end of the first secondary winding; wherein the first end of the first secondary winding and the first end of the second secondary winding are like-named ends.

7. The high frequency chain micro inverter according to claim 1, characterized in that: The inverter circuit includes a first primary switch tube, a second primary switch tube, a second capacitor and a third capacitor; The first pole of the first primary switch tube and the first pole of the second capacitor are connected to the positive end of the DC power supply end, the second pole of the first primary switch tube is connected to the first pole of the second primary switch tube and is connected to the second end of the primary winding, the second pole of the second capacitor is connected to the first pole of the third capacitor and is connected to the first end of the primary winding, and the second pole of the third capacitor and the second pole of the second primary switch tube are connected to the negative end of the DC power supply end.

8. The high frequency chain micro inverter according to claim 1, characterized in that: The inverter circuit includes a third primary switch tube, a fourth primary switch tube, a fifth primary switch tube and a sixth primary switch tube; The first pole of the third primary switch tube and the first pole of the fourth primary switch tube are connected to the positive end of the DC power supply end, the second pole of the third primary switch tube is connected to the first pole of the fifth primary switch tube and is connected to the first end of the primary winding, the second pole of the fourth primary switch tube is connected to the first pole of the sixth primary switch tube and is connected to the second end of the primary winding, and the second pole of the fifth primary switch tube and the second pole of the sixth primary switch tube are connected to the negative end of the DC power supply end.

9. The high-frequency chain-link micro-inverter according to claim 1, characterized in that: The inverter circuit includes a seventh primary switch tube and an eighth primary switch tube; The first pole of the seventh primary switch tube and the first pole of the eighth primary switch tube are connected to the negative end of the DC power supply end, the second pole of the seventh primary switch tube is connected to the first end of the primary winding, the second pole of the eighth primary switch tube is connected to the second end of the primary winding, and the center tap of the primary winding is connected to the positive end of the DC power supply end.

10. A photovoltaic power generation system, characterized in that: A high-frequency chain-link micro-inverter comprising any one of claims 1 to 9.

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