High-frequency chain micro-inverter and photovoltaic power generation system

Abstract

A high-frequency chain micro-inverter and a photovoltaic power generation system. The high-frequency chain micro-inverter comprises an inverter circuit (10), a transformer module (20), and a buck-boost circuit (30); an input end of the inverter circuit (10) is configured to be connected to a direct current power supply end (VIN), an output end of the inverter circuit (10) is connected to a primary winding (Np) of the transformer module (20), a secondary winding (Ns) of the transformer module (20) is connected to the buck-boost circuit (30), and an output end of the buck-boost circuit (30) serves as an output end of the high-frequency chain micro-inverter; the inverter circuit (10) is configured to perform inversion on the basis of a direct current signal provided by the direct current power supply end (VIN), to form a first alternating current signal; the transformer module (20) is configured to perform boost conversion on the basis of the first alternating current signal, to form a second alternating current signal; and the buck-boost circuit (30) is configured to perform buck-boost conversion on the second alternating current signal, to form a sinusoidal signal.

Description

High-frequency chain micro-inverter and photovoltaic power generation system

[0001] This application claims priority to the Chinese patent application No. 202411064143.9 filed on August 5, 2024 with the Chinese Patent Office, the whole content of the above application is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of photovoltaic power generation, for example, to a high-frequency chain micro-inverter and photovoltaic power generation system. BACKGROUND

[0003] The boost capability of the high-frequency chain inverter depends on the high-voltage ratio of the boost transformer. When the high-frequency chain inverter has a high voltage ratio, the boost transformer has high loss and high parasitic parameters, which reduces the performance of the high-frequency chain inverter.

[0004] SUMMARY

[0005] The present application provides a high-frequency chain micro-inverter and photovoltaic power generation system to improve the performance of the high-frequency chain inverter.

[0006] In a first aspect, the embodiments of the present application provide a high-frequency chain micro-inverter, comprising an inverter circuit, a transformer module and a boost-buck circuit.

[0007] The input end of the inverter circuit is connected with the DC power supply end, the output end of the inverter circuit is connected with the primary winding of the transformer module, the secondary winding of the transformer module is connected with the boost-buck circuit, and the output end of the boost-buck circuit is the output end of the high-frequency chain micro-inverter; the inverter circuit is configured to invert the DC signal provided by the DC power supply end to form a first AC signal; the transformer module is configured to perform boost conversion on the first AC signal to form a second AC signal; and the boost-buck circuit is configured to perform boost-buck conversion on the second AC signal to form a sinusoidal signal.

[0008] Optionally, the boost-buck circuit comprises a buck-boost circuit.

[0009] The first end of the buck-boost circuit is connected with the first end of the secondary winding of the transformer module, the output end of the buck-boost circuit is the output end of the high-frequency chain micro-inverter, and the second end of the buck-boost circuit is connected with the second end of the secondary winding of the transformer module; and the buck-boost circuit is configured to perform boost-buck conversion on the half-cycle signal of the second AC signal.

[0010] Optionally, the buck-boost circuit comprises a first switch unit, a second switch unit, a first capacitor and a first inductor.

[0011] The first end of the first switch unit is connected with the first end of the secondary winding of the transformer module, the second end of the first switch unit is connected with 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 with the first pole of the first capacitor and serves as the output end of the high-frequency chain micro inverter, and the second end of the first inductor and the second pole of the first capacitor are connected with the second end of the secondary winding of the transformer module; the first switch unit and the second switch unit are turned on at different times.

[0012] Optionally, the first switch unit comprises a first secondary switch tube and a second secondary switch tube, and the second switch unit comprises a third secondary switch tube and a fourth secondary switch tube.

[0013] The first pole of the first secondary switch tube is connected with the first end of the secondary winding of the transformer module, the second pole of the first secondary switch tube is connected with the second pole of the second secondary switch tube, the first pole of the second secondary switch tube is connected with the first pole of the third secondary switch tube and the first end of the first inductor, the second pole of the third secondary switch tube is connected with the second pole of the fourth secondary switch tube, and the first pole of the fourth secondary switch tube is connected with the first pole of the first capacitor; the first secondary switch tube and the second secondary switch tube are synchronously turned on or turned off, and the third secondary switch tube and the fourth secondary switch tube are synchronously turned on or turned off.

[0014] Optionally, when the boost-buck circuit comprises two buck-boost circuits, the two buck-boost circuits are arranged to perform boost-buck conversion on at least one half-cycle signal of the second alternating-current signal.

[0015] Optionally, the secondary winding comprises a first secondary winding and a second secondary winding.

[0016] The first ends of the two buck-boost circuits are respectively connected with the first ends of the first secondary winding and the second secondary winding, the second end of the first secondary winding is grounded together with the second end of the second secondary winding, and the second end of each buck-boost circuit is connected with the second end of the first secondary winding; wherein the first ends of the first secondary winding and the second secondary winding are the same-named ends.

[0017] Optionally, the inverter circuit comprises a first primary switch tube, a second primary switch tube, a second capacitor and a third capacitor.

[0018] The first pole of the first primary side switch tube and the first pole of the second capacitor are arranged to be connected with the positive terminal of the DC power supply end, the second pole of the first primary side switch tube is connected with the first pole of the second primary side switch tube, and the second pole of the first primary side switch tube is connected with the second terminal of the primary winding, the second pole of the second capacitor is connected with the first pole of the third capacitor, and the second pole of the second capacitor is connected with the first terminal of the primary winding, and the second pole of the third capacitor and the second pole of the second primary side switch tube are arranged to be connected with the negative terminal of the DC power supply end.

[0019] Optionally, the inverter circuit comprises a third primary side switch tube, a fourth primary side switch tube, a fifth primary side switch tube and a sixth primary side switch tube.

[0020] The first pole of the third primary side switch tube and the first pole of the fourth primary side switch tube are arranged to be connected with the positive terminal of the DC power supply end, the second pole of the third primary side switch tube is connected with the first pole of the fifth primary side switch tube, and the second pole of the third primary side switch tube is connected with the first terminal of the primary winding, the second pole of the fourth primary side switch tube is connected with the first pole of the sixth primary side switch tube, and the second pole of the fourth primary side switch tube is connected with the second terminal of the primary winding, the second pole of the fifth primary side switch tube and the second pole of the sixth primary side switch tube are arranged to be connected with the negative terminal of the DC power supply end.

[0021] Optionally, the inverter circuit comprises a seventh primary side switch tube and an eighth primary side switch tube.

[0022] The first pole of the seventh primary side switch tube and the first pole of the eighth primary side switch tube are arranged to be connected with the negative terminal of the DC power supply end, the second pole of the seventh primary side switch tube is connected with the first terminal of the primary winding, the second pole of the eighth primary side switch tube is connected with the second terminal of the primary winding, and the center tap of the primary winding is arranged to be connected with the positive terminal of the DC power supply end.

[0023] In a second aspect, the embodiments of the present application further provide a photovoltaic power generation system, comprising the high-frequency chain micro-inverter, a photovoltaic panel and a power grid in the first aspect; the photovoltaic panel and the high-frequency chain micro-inverter are connected through a power transmission line, and the high-frequency chain micro-inverter and the power grid are connected through a power transmission line. BRIEF DESCRIPTION OF DRAWINGS

[0024] FIG. 1 is a structural schematic diagram of a high-frequency chain inverter;

[0025] FIG. 2 is an equivalent voltage output principle diagram of a high-frequency chain micro-inverter;

[0026] FIG. 3 is a structural schematic diagram of a high-frequency chain micro-inverter provided by the embodiments of the present application;

[0027] FIG. 4 is a principle schematic diagram of a boost-buck circuit provided by the embodiments of the present application;

[0028] Fig. 5 is an equivalent voltage output schematic diagram of the voltage-lifting circuit provided in Fig. 4;

[0029] Fig. 6 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0030] Fig. 7 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0031] Fig. 8 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0032] Fig. 9 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0033] Fig. 10 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0034] Fig. 11 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0035] Fig. 12 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application;

[0036] Fig. 13 is a structural schematic diagram of a photovoltaic power generation system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] The present application will be described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, in order to facilitate the description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0038] Fig. 1 is a structural schematic diagram of a high-frequency chain inverter, and Fig. 2 is an equivalent voltage output schematic diagram of a high-frequency chain micro-inverter. As shown in Fig. 1 and Fig. 2, the direct current provided by the direct current power supply end is output to the primary winding of the transformer after passing through the full-bridge circuit of the primary side, and then the sine signal is output after passing through the secondary side conversion circuit after the transformer is boosted, so as to realize the inversion of the direct current. In the related art, the secondary side conversion circuit is an alternating buck circuit composed of back-to-back switch tubes and output filter inductors. That is, the switch tube connected back-to-back by the first switch tube Q1 and the second switch tube Q2, the switch tube connected back-to-back by the third switch tube Q3 and the fourth switch tube Q4, and the output filter inductor constitute a half-bridge secondary side conversion circuit 101, and then two half-bridge secondary side conversion circuits 101 constitute an alternating buck circuit. Taking the half-bridge secondary side conversion circuit 101 as an example, D Q1 is the duty ratio of the first switch tube Q1 and the second switch tube Q2 in the period of the half-bridge secondary side conversion circuit 101. Tsw1 is a high frequency switching period. 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 alternating current output. Because: 0≤D Q1 ≤0.5T sw1

[0039] then: 0≤v o1 ≤0.5n1V in1 , 0≤v o2 ≤0.5n1V in1 , v o1m =D Q1 n1V in1 ;

[0040] wherein V in1 is a direct current voltage provided by a direct current power supply end, n1 is a transformer ratio, v an1 is a voltage of a node a1 between the first switch tube Q1 and the third switch tube Q3 to ground, which is n1V in1 . v s1 is a voltage between two ends of a secondary side winding, which is an alternating square wave voltage with an amplitude of n1V in1 . v o1 is an output voltage of a first phase output end o1 of the high frequency chain micro-inverter, v o2 is an output voltage of a second phase output end o2 of the high frequency chain micro-inverter, and v o1m is an output voltage between the first phase output end o1 and the second phase output end o2 of the high frequency chain micro-inverter.

[0041] 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 transformer secondary side winding. 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 relatively high ratio, which results in high loss and high parasitic parameters of the step-up transformer, and reduces the performance of the high frequency chain micro-inverter.

[0042] The embodiment of the present application provides a high frequency chain micro-inverter. FIG. 3 is a structural schematic diagram of a high frequency chain micro-inverter provided by the embodiment of the present application. As shown in FIG. 3, the high frequency chain micro-inverter comprises an inverter circuit 10, a transformer module 20 and a step-up / down circuit 30; an input end of the inverter circuit 10 is connected with a direct current power supply end VIN, and an output end of the inverter circuit 10 is connected with a primary side winding N p of the transformer module 20, and a secondary side winding N sThe output end of the boost-buck circuit 30 is connected with the high-frequency chain micro-inverter, and the output end of the boost-buck circuit 30 is used as an output end VOUT of the high-frequency chain micro-inverter; the inverter circuit 10 is configured to invert a direct current signal provided by the direct current power supply end VIN to form a first alternating current signal; the voltage transformation module 20 is configured to perform boost transformation on the first alternating current signal to form a second alternating current signal; and the boost-buck circuit 30 is configured to perform boost-buck transformation on the second alternating current signal to form a sine signal.

[0043] The high-frequency chain micro-inverter can be applied to a photovoltaic power generation system. The direct current power supply end VIN of the high-frequency chain micro-inverter can be connected with an output end of a photovoltaic cell panel, so that the input signal provided by the signal input end VIN is a direct current. The inverter circuit 10 can invert the direct current signal provided by the direct current power supply end VIN to form a first alternating current signal. At this time, the first alternating current signal can be an alternating square wave signal. The voltage transformation module 20 can include a transformer, and the transformer performs boost transformation on the first alternating current signal to form a second alternating current signal. At this time, the voltage ratio of the second alternating current signal to the first alternating current signal is the transformation ratio of the transformer. Then, the boost-buck circuit 30 performs boost-buck transformation on the second alternating current signal and performs a filtering action, so that the boost-buck circuit 30 outputs a sine signal, thereby realizing inversion of the direct current signal provided by the direct current power supply end VIN. When the boost-buck circuit 30 performs boost-buck transformation on the second alternating current signal, the boost-buck circuit 30 can perform boost-buck transformation on the signal of the positive half cycle and / or the negative half cycle of the second alternating current signal. When the boost-buck circuit 30 performs boost-buck transformation on the half cycle signal of the second alternating current signal, the switching period of the boost-buck circuit 30 is equal to the period of the second alternating current signal. The boost-buck circuit 30 includes an energy storage stage and a discharge stage, and by adjusting the ratio of the energy storage stage to the switching period in the boost-buck circuit 30, the transformation ratio of the boost-buck circuit 30 can be adjusted, so that the transformation ratio of the sine signal to the second alternating current signal can be adjusted.

[0044] For example, FIG. 4 is a schematic diagram of a boost-buck circuit provided by an embodiment of the present application, and FIG. 5 is an equivalent voltage output schematic diagram of the boost-buck circuit provided by FIG. 4. As shown in FIG. 4 and FIG. 5, the boost-buck circuit 30 can include a buck-boost circuit. The buck-boost circuit includes an energy storage switch Q 1,2 , a discharge switch Q 3,4 , a filter inductor L1 and a filter capacitor C1, a first end of the energy storage switch Q 1,2 is connected with a first end of a secondary winding N s of the voltage transformation module 30, a second end of the energy storage switch Q 1,2 is connected with a first end of the discharge switch Q 3,4 and a first end of the filter inductor L1, and a second end of the discharge switch Q 3,4The second terminal of the filter inductor L1 is connected to the first terminal of the filter capacitor C1 and serves as the output terminal VOUT of the high-frequency chain-type micro inverter. The second terminal of the filter inductor L1 and the second terminal of the filter capacitor C1 are connected to the secondary winding N of the transformer module 30. s The second terminal is connected. During the energy storage phase, the energy storage switch Q... 1,2 Turn on, discharge switch Q 3,4 When the circuit is turned off, the filter inductor L1 is charged, and the voltage across the filter inductor L1 is equal to the voltage across the secondary winding N of the transformer module 30. s The voltage provided. During the discharge phase, the energy storage switch Q... 1,2 Turn off, discharge switch Q 3,4 When the circuit is turned on, the filter inductor L1 discharges through the discharge switch Q. 3,4 Discharge supplies power to the output VOUT of the high-frequency chain-type microinverter. Energy storage switch Q... 1,2 and discharge switch Q 3,4 The switching period of the first AC signal is equal to the period of the second AC signal. The second AC signal is an AC signal, causing the energy storage switch Q to... 1,2 The duty cycle of the second AC signal is less than or equal to half a cycle of the second AC signal. That is, T sw During the high-frequency switching cycle, the energy storage switch Q 1,2 Duty cycle D Q The range is: 0≤D Q ≤0.5T sw ,

[0045] The voltage v at the output terminal VOUT of the high-frequency chain micro inverter is... out For: 0≤v out ≤nV in ;

[0046] Among them, V in The DC voltage supplied to the DC power supply terminal VIN, where n is the turns ratio of transformer module 20. an For energy storage switch Q 1,2 With discharge switch Q 3,4 The voltage of node a to ground between them is nV. in v s For secondary winding N s The voltage across the terminals has an amplitude of nV. in AC square wave voltage, v out VOUT is the output voltage of the high-frequency chain-type micro inverter.

[0047] At this time, by adjusting the energy storage switch Q... 1,2 Duty cycle D Q This allows the maximum voltage at the output terminal VOUT of the high-frequency chain-type microinverter to be equal to the voltage at the secondary winding N of the transformer module 20. sThe output voltage can be increased on the basis of the unchanged transformation ratio of the transformer module 20, so that the gain of the high-frequency chain micro-inverter can be increased. When the gain of the high-frequency chain micro-inverter is required to be unchanged, the demand for the transformation ratio of the transformer module 20 can be reduced, so that the efficiency loss caused by the parasitic parameters of the transformer module 20 can be reduced, and the efficiency of the high-frequency chain micro-inverter is increased. Moreover, the voltage transformation ratio of the high-frequency chain micro-inverter can be adjusted by adjusting the duty cycle D 1,2 of the energy storage switch tube Q Q , so that the gain of the high-frequency chain micro-inverter can be adjusted.

[0048] The technical scheme of the embodiment can increase the gain of the high-frequency chain micro-inverter by setting the boost-buck circuit to perform boost-buck conversion on the second alternating current signal output by the transformer module. When the gain of the high-frequency chain micro-inverter is required to be unchanged, the demand for the transformation ratio of the transformer module can be reduced, so that the efficiency loss caused by the parasitic parameters of the transformer module can be reduced, and the efficiency of the high-frequency chain micro-inverter is increased. 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, so that the gain of the high-frequency chain micro-inverter can be adjusted.

[0049] FIG. 6 is a structural schematic diagram of another high-frequency chain micro-inverter provided by the embodiment of the application. As shown in FIG. 6, the boost-buck circuit 30 includes at least one buck-boost circuit; the first end of the buck-boost circuit is connected with the first end of the secondary winding N S of the transformer module 20, the output end of the buck-boost circuit is used as the output end VOUT of the high-frequency chain micro-inverter, the second end of the buck-boost circuit is connected with the second end of the secondary winding N S of the transformer module 20; the buck-boost circuit is set to perform boost-buck conversion on the half-period signal of the second alternating current signal.

[0050] The boost-buck circuit 30 includes one buck-boost circuit, and the transformer module 20 is a double-winding transformer, which is exemplarily shown in FIG. 6. The first end of the buck-boost circuit is connected with the first end of the secondary winding N S of the transformer module 20, and the second end of the buck-boost circuit is connected with the second end of the secondary winding N Sthe second end of the first switch unit 301 and the first end of the second switch unit 302 are connected with the first end of the first inductor L1 and the first end of the secondary winding N2 of the transformer module 20. The second end of the second switch unit 302 is connected with the first end of the first capacitor C1 and serves as the output terminal VOUT of the high-frequency chain micro-inverter. The second end of the first inductor L1 and the second end of the first capacitor C1 are connected with the second end of the secondary winding N2 of the transformer module 20. The first switch unit 301 and the second switch unit 302 are turned on at different times. in Thus, the gain of the high-frequency chain micro-inverter can be increased by the buck-boost circuit, and the gain of the high-frequency chain micro-inverter is adjustable.

[0051] Alternatively, when the second alternating signal is in the negative half cycle, the buck-boost circuit can be controlled to be in the energy storage stage, so that the energy of the negative half cycle of the second alternating signal is stored by the buck-boost circuit. When the second alternating signal is in the positive half cycle, the buck-boost circuit can be controlled to be in the discharging stage, so that the stored energy is discharged by the buck-boost circuit. At this time, the ratio of the discharging voltage of the buck-boost circuit to the voltage of the negative half cycle of the second alternating signal is adjusted according to the duty ratio 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 alternating signal can be expanded to nV in , and the gain of the high-frequency chain micro-inverter can also be increased, and the gain of the high-frequency chain micro-inverter is adjustable.

[0052] With reference still to FIG. 6, the buck-boost circuit comprises a first switch unit 301, a second switch unit 302, a first capacitor C1 and a first inductor L1. f The first end of the first switch unit 301 is connected with the first end of the secondary winding N2 of the transformer module 20. The second end of the first switch unit 301 is connected with the first end of the first inductor L1 and the first end of the second switch unit 302. The second end of the second switch unit 302 is connected with the first end of the first capacitor C1 and serves as the output terminal VOUT of the high-frequency chain micro-inverter. The second end of the first inductor L1 and the second end of the first capacitor C1 are connected with the second end of the secondary winding N2 of the transformer module 20. The first switch unit 301 and the second switch unit 302 are turned on at different times. f S f f f f S

[0053] ​​​​​​​As shown in FIG. 6, when the first switch unit 301 is turned on and the second switch unit 302 is turned off, the first switch unit 301, the first inductor L f and the secondary winding N S form an energy storage loop, so that the first inductor L f stores the electric energy provided by 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, the first inductor L f and the first capacitor C f form a discharge loop, so that the first inductor L f provides electric energy through the output terminal VOUT of the high-frequency chain micro-inverter. The duty ratio of the first switch unit 301 is the ratio of the on time of the first switch unit 301 to the working period of the buck-boost circuit. Since the second alternating current signal is an alternating current signal, the duty ratio of the first switch unit 301 is less than or equal to 0.5. Therefore, the discharge voltage v f of the first inductor L out is less than or equal to the voltage nV S provided by the secondary winding N in , so that the output voltage of the high-frequency chain micro-inverter can be multiplied, the requirement for the transformation ratio of the transformer module 20 is reduced, the efficiency loss caused by the parasitic parameters of the transformer module 20 is reduced, and the efficiency of the high-frequency chain micro-inverter is increased. At the same time, the gain of the high-frequency chain micro-inverter can be adjusted by adjusting the duty ratio of the first switch unit 301, so that the gain of the high-frequency chain micro-inverter is adjustable.

[0054] Continuing to refer to FIG. 6, the first switch unit 301 includes a first secondary switch Q1 and a second secondary switch Q2, and the second switch unit 302 includes a third secondary switch Q3 and a fourth secondary switch Q4; the first pole of the first secondary switch Q1 is connected with the first end of the secondary winding N S of the transformer module 20, the second pole of the first secondary switch Q1 is connected with the second pole of the second secondary switch Q2, the first pole of the second secondary switch Q2 is connected with the first pole of the third secondary switch Q3 and the first end of the first inductor L f , the second pole of the third secondary switch Q3 is connected with the second pole of the fourth secondary switch Q4, and the first pole of the fourth secondary switch Q4 is connected with the first pole of the first capacitor C f ; the first secondary switch Q1 and the second secondary switch Q2 are synchronously turned on or turned off, and the third secondary switch Q3 and the fourth secondary switch Q4 are synchronously turned on or turned off.

[0055] The first auxiliary side switch Q1 and the second auxiliary side switch Q2 can be connected in series in a back-to-back manner, and the third auxiliary side switch Q3 and the fourth auxiliary side switch Q4 can also be connected in series in a back-to-back manner. By setting the first auxiliary side switch Q1 and the second auxiliary side switch Q2 in a back-to-back manner and the third auxiliary side switch Q3 and the fourth auxiliary side switch Q4 in a back-to-back manner, the high-frequency chain micro-inverter has a reactive power support capability. At the same time, it is beneficial to realize the commutation of the buck-boost circuit, optimize the current path of the buck-boost circuit, and improve the efficiency of the buck-boost circuit.

[0056] With reference to FIG. 6, the inverter circuit 10 comprises a first primary side switch T1, a second primary side switch T2, a second capacitor C2 and a third capacitor C3; the first pole of the first primary side switch T1 and the first pole of the second capacitor C2 are connected to the positive terminal + of the DC power supply end VIN, the second pole of the first primary side switch T1 is connected to the first pole of the second primary side switch T2 and the second terminal M2 of the primary winding N p , the second pole of the second capacitor C2 is connected to the first pole of the third capacitor C3 and the first terminal M1 of the primary winding N p , and the second pole of the third capacitor C3 and the second pole of the second primary side switch T2 are connected to the negative terminal - of the DC power supply end VIN.

[0057] The inverter circuit 10 is shown as a half-bridge inverter circuit in FIG. 6. When the first primary side switch T1 is turned on and the second primary side switch T2 is turned off, the voltage provided by the DC power supply end VIN flows from the second terminal M2 of the primary winding N p to the first terminal M1 of the primary winding N p to the first pole of the third capacitor C3 through the first primary side switch T1, and then is transmitted to the negative terminal - of the DC power supply end VIN through the third capacitor C3. At this time, the voltage of the primary winding N p is positive at the second terminal M2 and negative at the first terminal M1. When the first primary side switch T1 is turned off and the second primary side switch T2 is turned on, the second pole voltage of the second capacitor C2 flows from the first terminal M1 of the primary winding N p to the second terminal M2 of the primary winding N p , and is transmitted to the negative terminal - of the DC power supply end VIN through the second primary side switch T2. At this time, the voltage of the primary winding N p is positive at the first terminal M1 and negative at the second terminal M2. Thus, the inversion of the DC signal provided by the DC power supply end VIN is realized.

[0058] Fig. 7 is a structural schematic diagram of another high-frequency chain micro-inverter provided by the embodiment of the present application. As shown in Fig. 7, the inverter circuit 10 comprises a third primary-side switch tube T3, a fourth primary-side switch tube T4, a fifth primary-side switch tube T5 and a sixth primary-side switch tube T6; the first poles of the third primary-side switch tube T3 and the fourth primary-side switch tube T4 are connected with the positive terminal + of the DC power supply end VIN, the second pole of the third primary-side switch tube T3 is connected with the first pole of the fifth primary-side switch tube T5 and the first end M1 of the primary winding N p , and the second pole of the fourth primary-side switch tube T4 is connected with the first pole of the sixth primary-side switch tube T6 and the second end M2 of the primary winding N p ; the second poles of the fifth primary-side switch tube T5 and the sixth primary-side switch tube T6 are connected with the negative terminal - of the DC power supply end VIN.

[0059] The inverter circuit 10 is a full-bridge inverter circuit as exemplarily shown in Fig. 7. When the third primary-side switch tube T3 and the sixth primary-side switch tube T6 are turned on and the fourth primary-side switch tube T4 and the fifth primary-side switch tube T5 are turned off, the voltage provided by the DC power supply end VIN flows from the positive terminal + of the DC power supply end VIN through the third primary-side switch tube T3 to the first end M1 of the primary winding N p , and then flows to the second end M2 of the primary winding N p , and is transmitted to the negative terminal - of the DC power supply end VIN through the sixth primary-side switch tube T6. At this time, the voltage of the primary winding N p is positive at the first end M1 and negative at the second end M2. When the third primary-side switch tube T3 and the sixth primary-side switch tube T6 are turned off and the fourth primary-side switch tube T4 and the fifth primary-side switch tube T5 are turned on, the voltage provided by the DC power supply end VIN flows from the positive terminal + of the DC power supply end VIN through the fourth primary-side switch tube T4 to the second end M2 of the primary winding N p , and then flows to the first end M1 of the primary winding N p , and is transmitted to the negative terminal - of the DC power supply end VIN through the fifth primary-side switch tube T5. At this time, the voltage of the primary winding N p is positive at the second end M2 and negative at the first end M1. Thus, the inversion of the DC signal provided by the DC power supply end VIN is realized.

[0060] Fig. 8 is a structural schematic diagram of another high-frequency chain micro-inverter provided by the embodiment of the present application. As shown in Fig. 8, the inverter circuit comprises a seventh primary-side switch tube T7 and an eighth primary-side switch tube T8; the first poles of the seventh primary-side switch tube T7 and the eighth primary-side switch tube T8 are connected with the negative terminal - of the DC power supply end VIN, the second pole of the seventh primary-side switch tube T7 is connected with the first end M1 of the primary winding N p , and the second pole of the eighth primary-side switch tube T8 is connected with the second end M2 of the primary winding N p ; the primary winding Np The center tap M0 of the primary winding N is connected to the positive terminal + of the DC power supply terminal VIN.

[0061] The inverter circuit 10 is a push-pull inverter circuit as shown in FIG. 8. When the seventh primary switch T7 is turned on and the eighth primary switch T8 is turned off, the voltage provided by the DC power supply terminal VIN is transmitted from the positive terminal + of the DC power supply terminal VIN to the negative terminal - of the DC power supply terminal VIN through the seventh primary switch T7, and the part of the primary winding N from the center tap M0 to the first end M1. At this time, the voltage of the primary winding N is positive at the center tap M0 and negative at the first end M1. p p When the seventh primary switch T7 is turned off and the eighth primary switch T8 is turned on, the voltage provided by the DC power supply terminal VIN is transmitted from the positive terminal + of the DC power supply terminal VIN to the negative terminal - of the DC power supply terminal VIN through the eighth primary switch T8, and the part of the primary winding N from the center tap M0 to the second end M2. At this time, the voltage of the primary winding N is positive at the center tap M0 and negative at the second end M2. p p Thus, the inverting of the DC signal provided by the DC power supply terminal VIN is realized.

[0062] FIGS. 6-8 only illustrate some circuit types of the inverter circuit 10. In other embodiments, the inverter circuit 10 can be any high-frequency AC square wave generator. In addition, the inverter circuit 10 can also include other types of circuits. For example, the inverter circuit 10 can include at least two stages of circuits, and the different stages of circuits can include buck-boost circuits and inverter circuits. In addition, the different stages of circuits can share devices, which are not limited herein.

[0063] FIG. 9 is a structural schematic diagram of another high-frequency chain micro inverter provided by the embodiments of the present application. As shown in FIG. 9, the buck-boost circuit 30 can also include two buck-boost circuits. The two buck-boost circuits are configured to perform buck-boost conversion on at least one half-cycle signal of the second AC signal.

[0064] ​​As shown in FIG. 9, when the voltage-lifting and voltage-lowering circuit 30 includes two buck-boost circuits, the two buck-boost circuits can be connected in a split phase manner. That is, each buck-boost circuit is connected in the same manner, and the output end of each buck-boost circuit is respectively used as a 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 with a load, different single-phase output ends can be respectively connected with different or same loads, and are configured to supply power to the loads. Moreover, the single-phase output end of the high-frequency chain micro-inverter can be connected with a power grid, so as to realize grid-connected operation of the high-frequency chain micro-inverter. The second alternating-current signal is an alternating-current signal. During operation of the voltage-lifting and voltage-lowering circuit 30, one buck-boost circuit can be controlled to perform voltage-lifting and voltage-lowering conversion on the second alternating-current signal in a positive half cycle of the second alternating-current signal, and the other buck-boost circuit can be controlled to perform voltage-lifting and voltage-lowering conversion on the second alternating-current signal in a negative half cycle of the second alternating-current signal, thereby improving the utilization rate of the second alternating-current signal, and further improving the efficiency of the high-frequency chain micro-inverter.

[0065] For example, as shown in FIG. 9, 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 switching unit 311, a first second switching unit 312, a first first inductor L f1 and a first first capacitor C f1 . The first first switching unit 311 includes a first first auxiliary side switch Q11 and a first second auxiliary side switch Q21, and the first second switching unit 312 includes a first third auxiliary side switch Q31 and a first fourth auxiliary side switch Q41; the first buck-boost circuit 31 is connected in the same manner as one buck-boost circuit, and a first pole of the first first capacitor C f1 is used as a first single-phase output end VOUT1 of the high-frequency chain micro-inverter. The second buck-boost circuit 32 includes a second first switching unit 321, a second second switching unit 322, a second first inductor L f2 and a second first capacitor C f2 . The second first switching unit 321 includes a second first auxiliary side switch Q12 and a second second auxiliary side switch Q22, and the second second switching unit 322 includes a second third auxiliary side switch Q32 and a second fourth auxiliary side switch Q42; the second buck-boost circuit 32 is connected in the same manner as one buck-boost circuit, and the second first capacitor C f2the first primary side switch Q11 and the second primary side switch Q21, and the third secondary side switch Q32 and the fourth secondary side switch Q42 are turned off, and the first secondary side switch Q12 and the second secondary side switch Q22 are turned on. At this time, the first inductor L f1 stores the electric energy of the positive half cycle of the second alternating current signal, and the second inductor L f2 is discharged through the third secondary side switch Q32 and the fourth secondary side switch Q42. In the negative half cycle of the second alternating current signal, the first primary side switch Q11 and the second primary side switch Q21, and the third secondary side switch Q32 and the fourth secondary side switch Q42 are turned off, and the first secondary side switch Q12 and the second secondary side switch Q22 are turned on. At this time, the second inductor L f2 stores the electric energy of the negative half cycle of the second alternating current signal, and the first inductor L f1 is discharged through the first secondary side switch Q12 and the second secondary side switch Q22. Thus, the full cycle signal of the second alternating current signal can be step-up and step-down converted, the utilization rate of the second alternating current signal is improved, and the efficiency of the high-frequency chain micro-inverter is improved.

[0066] The inverter circuit 10 is a half-bridge inverter circuit, which is shown in FIG. 9. In other embodiments, the inverter circuit 10 can also be a full-bridge inverter circuit and a push-pull inverter circuit. For example, FIG. 10 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application. As shown in FIG. 10, the inverter circuit 10 is the same as the inverter circuit 10 provided in FIG. 7, and both are full-bridge inverter circuits. FIG. 11 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application. As shown in FIG. 11, the inverter circuit 10 is the same as the inverter circuit 10 provided in FIG. 8, and both are push-pull inverter circuits.

[0067] In some embodiments, FIG. 12 is a structural schematic diagram of another high-frequency chain micro-inverter provided in an embodiment of the present application. As shown in FIG. 12, the secondary side winding N S includes a first secondary side winding N S1 and a second secondary side winding N S2; the first end of the first buck-boost circuit is connected with the first end of the first secondary winding N S1 ; the first end of the second buck-boost circuit is connected with the first end of the second secondary winding N S2 ; the second end of the first secondary winding N S1 is grounded; the second end of the second secondary winding N S2 ; the second end of each buck-boost circuit is connected with the second end of the first secondary winding N S1 ; the first end of the first secondary winding N S1 and the first end of the second secondary winding N S2 are the same end.

[0068] The transformer module 20 can be a single three-winding high-frequency transformer, the primary winding of the transformer has a single primary winding N p , the secondary winding of the transformer has a first secondary winding N s1 and a second secondary winding N S2 ; the first end of the first buck-boost circuit 31 is connected with the first end of the first secondary winding N S1 ; the first end of the second buck-boost circuit 32 is connected with the first end of the second secondary winding N S2 ; the second end of the first buck-boost circuit 31 and the second end of the second buck-boost circuit 32 are grounded. At this time, by controlling the working state of the two buck-boost circuits, the step-up and step-down conversion of the second alternating current 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 similar to the control process of FIGS. 9-11, which will not be described here.

[0069] In some embodiments, the transformer module can also be provided to include a first transformer and a second transformer, the inverter circuit is connected with the primary winding of the first transformer and the primary winding of the second transformer, and the secondary winding of the first transformer and the secondary winding of the second transformer are respectively connected with the two buck-boost circuits. Similarly, the step-up and step-down conversion of the second alternating current signal can also be realized to output in phase.

[0070] The application also provides a photovoltaic power generation system. As shown in FIG. 13, the photovoltaic power generation system includes the high-frequency chain micro-inverter provided by any embodiment of the application, a photovoltaic panel, and a power grid. The photovoltaic panel and the high-frequency chain micro-inverter are connected through a power transmission line, and the high-frequency chain micro-inverter and the power grid are connected through a power transmission line. The photovoltaic panel converts the received sunlight into direct current, and the high-frequency chain micro-inverter converts the direct current into alternating current, which is connected to the power grid through a power grid interface.

[0071] Since the photovoltaic power generation system comprises the high-frequency chain micro-inverter provided by any of the embodiments of the present application, the photovoltaic power generation system has the same effects as the high-frequency chain micro-inverter provided by any of the embodiments of the present application, and thus will not be described herein again.

Claims

1. A high-frequency chain micro-inverter, comprising an inverter circuit, a transformer module and a boost-buck circuit; an input end of the inverter circuit is arranged to be connected with a DC power end, an output end of the inverter circuit is connected with a primary winding of the transformer module, a secondary winding of the transformer module is connected with the boost-buck circuit, and an output end of the boost-buck circuit is an output end of the high-frequency chain micro-inverter; the inverter circuit is arranged to invert a DC signal provided by the DC power end to form a first AC signal; the transformer module is arranged to boost the first AC signal to form a second AC signal; and the boost-buck circuit is arranged to boost or buck the second AC signal to form a sinusoidal signal.

2. The high-frequency chain-link microinverter of claim 1, wherein, The boost-buck circuit comprises a buck-boost circuit. A first end of the buck-boost circuit is connected with a first end of the secondary winding of the transformer module, an output end of the buck-boost circuit is the output end of the high-frequency chain micro-inverter, a second end of the buck-boost circuit is connected with a second end of the secondary winding of the transformer module, and the buck-boost circuit is arranged to boost or buck a half-cycle signal of the second AC signal.

3. The high-frequency chain-link microinverter of claim 2, wherein, The buck-boost circuit comprises a first switching unit, a second switching unit, a first capacitor and a first inductor. A first end of the first switching unit is connected with the first end of the secondary winding of the transformer module, a second end of the first switching unit is connected with a first end of the first inductor and a first end of the second switching unit, a second end of the second switching unit is connected with a first pole of the first capacitor and is the output end of the high-frequency chain micro-inverter, a second end of the first inductor and a second pole of the first capacitor are connected with the second end of the secondary winding of the transformer module, and the first switching unit and the second switching unit are turned on at different times.

4. The high-frequency chain-link microinverter of claim 3, wherein, The first switching unit comprises a first secondary switching tube and a second secondary switching tube, and the second switching unit comprises a third secondary switching tube and a fourth secondary switching tube. A first pole of the first secondary switching tube is connected with the first end of the secondary winding of the transformer module, a second pole of the first secondary switching tube is connected with a second pole of the second secondary switching tube, a first pole of the second secondary switching tube is connected with a first pole of the third secondary switching tube and the first end of the first inductor, a second pole of the third secondary switching tube is connected with a second pole of the fourth secondary switching tube, and a first pole of the fourth secondary switching tube is connected with the first pole of the first capacitor; the first secondary switching tube and the second secondary switching tube are synchronously turned on or turned off, and the third secondary switching tube and the fourth secondary switching tube are synchronously turned on or turned off.

5. The high-frequency chain-link microinverter of any of claims 2-4, wherein, When the boost-buck circuit comprises two buck-boost circuits, the two buck-boost circuits are arranged to boost or buck at least one half-cycle signal of the second AC signal.

6. The high-frequency chain-link microinverter of claim 5, wherein, 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 with the first ends of the first and second secondary winding, the second end of the first secondary winding is grounded with the second end of the second secondary winding, and the second end of each buck-boost circuit is connected with the second end of the first secondary winding; wherein the first ends of the first and second secondary winding are the same name ends.

7. The high-frequency chain-link microinverter of claim 1, wherein, The inverter circuit comprises 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 arranged to be connected with the positive end of the DC power supply end, the second pole of the first primary switch tube is connected with the first pole of the second primary switch tube and the second end of the primary winding, the second pole of the second capacitor is connected with the first pole of the third capacitor and 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 arranged to be connected with the negative end of the DC power supply end.

8. The high-frequency chain-link microinverter of claim 1, wherein, The inverter circuit comprises 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 arranged to be connected with the positive end of the DC power supply end, the second pole of the third primary switch tube is connected with the first pole of the fifth primary switch tube and the first end of the primary winding, the second pole of the fourth primary switch tube is connected with the first pole of the sixth primary switch tube and 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 arranged to be connected with the negative end of the DC power supply end.

9. The high-frequency chain-link microinverter of claim 1, wherein, The inverter circuit comprises 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 arranged to be connected with the negative end of the DC power supply end, the second pole of the seventh primary switch tube is connected with the first end of the primary winding, the second pole of the eighth primary switch tube is connected with the second end of the primary winding, and the center tap of the primary winding is arranged to be connected with the positive end of the DC power supply end.

10. A photovoltaic power generation system comprising the high-frequency chain micro-inverter of any one of claims 1-9, a photovoltaic panel and a power grid; The photovoltaic panel and the high-frequency chain micro-inverter are connected through a power transmission wire, and the high-frequency chain micro-inverter and the power grid are connected through a power transmission wire. ​

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