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

Abstract

The application discloses a high-frequency chain type micro inverter and a photovoltaic power generation system. The high-frequency chain type micro inverter comprises an inverter circuit, a voltage transformation module and a boost-buck 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 the primary winding of the voltage transformation module, the secondary winding of the voltage transformation module is connected with the boost-buck circuit, and the output end of the boost-buck circuit serves as the output end of the high-frequency chain type micro inverter; the inverter circuit is used for inverting a direct-current signal provided by the direct-current power supply end to form a first alternating-current signal; the voltage transformation module is used for boosting and transforming the first alternating-current signal to form a second alternating-current signal; and the boost-buck circuit is used for boosting and bucking the second alternating-current signal to form a sinusoidal signal. The ratio requirement of the voltage transformation module can be reduced, the efficiency of the high-frequency chain type micro inverter is increased, and the gain of the high-frequency chain type micro inverter can be adjusted.

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 Technology

[0002] In existing technologies, the boost capability of high-frequency chain inverters relies on a high-ratio step-up transformer. When the ratio of a high-frequency chain inverter is too high, it leads to high losses and high parasitic parameters in the step-up transformer, reducing the performance of the high-frequency chain inverter. Summary of the Invention

[0003] This 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, embodiments of the present invention provide a high-frequency chain-type micro inverter, including an inverter circuit, a transformer module, and a buck-boost circuit;

[0005] The input terminal of the inverter circuit is connected to the DC power supply terminal, the output terminal 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 terminal of the buck-boost circuit serves as the output terminal of the high-frequency chain-type micro inverter. The inverter circuit is used to invert the DC signal provided by the DC power supply terminal to form a first AC signal. The transformer module is used to boost the first AC signal to form a second AC signal. The buck-boost circuit is used to buck-boost the second AC signal to form a sine wave signal.

[0006] Optionally, the buck-boost circuit includes at least one buck-boost circuit;

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

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

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

[0010] Optionally, the first switching unit includes a first secondary-side switching transistor and a second secondary-side switching transistor, and the second switching unit includes a third secondary-side switching transistor and a fourth secondary-side switching transistor;

[0011] The first terminal of the first secondary-side switching transistor is connected to the first end of the secondary winding of the transformer module; the second terminal of the first secondary-side switching transistor is connected to the second terminal of the second secondary-side switching transistor; the first terminal of the second secondary-side switching transistor is connected to the first terminal of the third secondary-side switching transistor and the first end of the first inductor; the second terminal of the third secondary-side switching transistor is connected to the second terminal of the fourth secondary-side switching transistor; and the first terminal of the fourth secondary-side switching transistor is connected to the first terminal of the first capacitor. The first and second secondary-side switching transistors are synchronously turned on or off, and the third and fourth secondary-side switching transistors are synchronously turned on or off.

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

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

[0014] The first terminals of the two buck-boost circuits are respectively connected to the first terminal of the first secondary winding and the first terminal of the second secondary winding. The second terminals of the first secondary winding and the second secondary winding are grounded. The second terminal of each buck-boost circuit is connected to the second terminal of the first secondary winding. The first terminals of the first secondary winding and the second secondary winding are terminals with the same name.

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

[0016] The first terminal of the first primary-side switching transistor and the first terminal of the second capacitor are connected to the positive terminal of the DC power supply. The second terminal of the first primary-side switching transistor is connected to the first terminal of the second primary-side switching transistor and is connected to the second terminal of the primary winding. The second terminal of the second capacitor is connected to the first terminal of the third capacitor and is connected to the first terminal of the primary winding. The second terminal of the third capacitor and the second terminal of the second primary-side switching transistor are connected to the negative terminal of the DC power supply.

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

[0018] The first poles of the third primary-side switch and the fourth primary-side switch are connected to the positive terminal of the DC power supply. The second pole of the third primary-side switch is connected to the first pole of the fifth primary-side switch and to the first terminal of the primary winding. The second pole of the fourth primary-side switch is connected to the first pole of the sixth primary-side switch and to the second terminal of the primary winding. The second poles of the fifth and sixth primary-side switches are connected to the negative terminal of the DC power supply.

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

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

[0021] Secondly, embodiments of the present invention also provide a photovoltaic power generation system, including the high-frequency chain micro-inverter described in the first aspect.

[0022] The technical solution of this invention increases the gain of the high-frequency chain microinverter by setting a step-up / step-down circuit to perform step-up / step-down conversion on the second AC signal output by the transformer module. When the gain requirement of the high-frequency chain microinverter remains unchanged, the transformation ratio requirement of the transformer module can be reduced, thereby reducing efficiency losses caused by parasitic parameters of the transformer module and increasing the efficiency of the high-frequency chain microinverter. Moreover, the voltage transformation ratio of the high-frequency chain microinverter can be adjusted by regulating the duty cycle of the energy storage switch, realizing adjustable gain of the high-frequency chain microinverter. Attached Figure Description

[0023] Figure 1 A schematic diagram of the structure of a high-frequency chain inverter provided for related technologies;

[0024] Figure 2 A schematic diagram of the equivalent voltage output of a high-frequency chain-type microinverter provided for related technologies;

[0025] Figure 3 This is a schematic diagram of the structure of a high-frequency chain-type micro inverter provided in an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a step-up / step-down circuit provided in an embodiment of the present invention;

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

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

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

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

[0031] Figure 9 A schematic diagram of another high-frequency chain-type micro inverter provided in an embodiment of the present invention;

[0032] Figure 10 A schematic diagram of another high-frequency chain-type micro inverter provided in an embodiment of the present invention;

[0033] Figure 11 A schematic diagram of another high-frequency chain-type micro inverter provided in an embodiment of the present invention;

[0034] Figure 12 This is a schematic diagram of another high-frequency chain-type micro inverter provided in an embodiment of the present invention. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0036] Figure 1 A schematic diagram of a high-frequency chain inverter is provided for related technologies. Figure 2 The equivalent voltage output schematic diagram of a high-frequency chain-type microinverter is provided for related technologies. (Example:) Figure 1 and Figure 2 As shown, the DC power supplied by the DC power source is output to the primary winding of the transformer after passing through the full-bridge circuit on the primary side. After being stepped up by the transformer, it passes through the secondary-side conversion circuit and outputs a sinusoidal signal, thus achieving DC inversion. In related technologies, the secondary-side conversion circuit consists of an AC buck circuit composed of back-to-back switching transistors and an output filter inductor. Specifically, a half-bridge secondary-side conversion circuit 101 is formed by the back-to-back connection of the first and second switching transistors Q1 and Q2, the back-to-back connection of the third and fourth switching transistors Q3 and Q4, and the output filter inductor. Two half-bridge secondary-side conversion circuits 101 then form an AC buck circuit. Taking the half-bridge secondary-side conversion circuit 101 as an example, D... Q1 T represents the duty cycle of the first switch Q1 and the second switch Q2 during the cycle of the half-bridge secondary-side converter circuit 101. sw1 This is the high-frequency switching cycle. For each half-bridge secondary converter circuit 101, only half a high-frequency square wave can be used to complete the phase-splitting 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 The DC voltage supplied to the DC power supply terminal, n1 is the transformer turns ratio, v an1 The voltage at node a1 between the first switch Q1 and the third switch Q3 and ground is n1V. in1 v s1 The voltage across the secondary winding is n1V. in1 AC square wave voltage. v o1 V is the output voltage at the first phase output terminal o1 of the high-frequency chain-type micro inverter. o2 The output voltage at the second phase output terminal o2 of the high-frequency chain-type micro inverter is v. o1m This is the output voltage between the first phase output terminal o1 and the second phase output terminal o2 of the high-frequency chain-type micro inverter.

[0043] The above analysis shows that the output voltage of a high-frequency chain-type microinverter is less than or equal to half the output voltage of the transformer's secondary winding. When the input voltage of the high-frequency chain-type microinverter is relatively low and the required output voltage is relatively high, the transformer needs to have a high turns ratio, resulting in high losses and high parasitic parameters in the step-up transformer, which reduces the performance of the high-frequency chain-type inverter.

[0044] To address the aforementioned technical problems, embodiments of the present invention provide a high-frequency chain-type micro inverter. Figure 3 This is a schematic diagram of a high-frequency chain-type microinverter provided as an embodiment of the present invention. Figure 3 As shown, the high-frequency chain-type micro inverter includes an inverter circuit 10, a transformer module 20, and a buck-boost circuit 30; the input terminal of the inverter circuit 10 is connected to the DC power supply terminal VIN, and the output terminal of the inverter circuit 10 is connected to the primary winding N of the transformer module 20. p Connection, secondary winding N of transformer module 20 s Connected to the step-up / step-down circuit 30, the output of the step-up / step-down circuit 30 serves as the output 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 step up the first AC signal to form a second AC signal; the step-up / step-down circuit 30 is used to step up / down the second AC signal to form a sine wave signal.

[0045] Specifically, high-frequency chain-type microinverters can be applied to photovoltaic power generation systems. The DC power supply terminal VIN of the high-frequency chain-type microinverter can be connected to the output terminal of the photovoltaic panel, so that the input signal provided by the signal input terminal VIN is DC. 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 can include a transformer, which 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 transformer turns ratio. Then, the buck-boost circuit 30 performs a buck-boost conversion on the second AC signal and performs filtering, so that the buck-boost circuit 30 outputs a sine wave signal, thereby realizing the inversion of the DC signal provided by the DC power supply terminal VIN. When the buck-boost circuit 30 performs a buck-boost conversion on the second AC signal, the buck-boost circuit 30 can perform buck-boost conversion on the positive half-cycle and / or 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 stage and a discharge stage. By adjusting the ratio of the energy storage stage 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 This is a schematic diagram of a step-up / step-down circuit provided in an embodiment of the present invention. Figure 5 for Figure 4 The provided schematic diagram shows the equivalent voltage output of the buck-boost circuit. Figure 4 and Figure 5 As shown, the buck-boost circuit 30 may include a buck-boost circuit. The buck-boost circuit includes an energy storage switch Q. 1,2 Discharge switch Q 3,4 Filter inductor L1 and filter capacitor C1, energy storage switch Q 1,2 The first end is connected to the secondary winding N of transformer module 30 s The first terminal is connected to the energy storage switch Q. 1,2 The second terminal is connected to the discharge switch Q. 3,4 The first terminal is connected to the first terminal of the filter inductor L1, and the discharge switch Q is connected. 3,4 The 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:

[0047] 0≤D Q ≤0.5T sw ,

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

[0049] 0 < vout ≤nV in ;

[0050]

[0051] 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.

[0052] 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. s The output voltage allows for an increase in the gain of the high-frequency chain microinverter while maintaining the same transformer ratio as related technologies. When the gain requirement of the high-frequency chain microinverter remains constant, the transformer ratio requirement for the transformer module 20 can be reduced, thereby minimizing efficiency losses caused by parasitic parameters of the transformer module 20 and increasing the efficiency of the high-frequency chain microinverter. Furthermore, the efficiency can be increased by adjusting the energy storage switch Q. 1,2 Duty cycle D Q By adjusting the voltage ratio of the high-frequency chain microinverter, the gain of the high-frequency chain microinverter can be made adjustable.

[0053] The technical solution in this embodiment increases the gain of the high-frequency chain microinverter by setting a step-up / step-down circuit to perform step-up / step-down conversion on the second AC signal output by the transformer module. When the gain requirement of the high-frequency chain microinverter remains unchanged, the transformation ratio requirement of the transformer module can be reduced, thereby reducing efficiency losses caused by parasitic parameters of the transformer module and increasing the efficiency of the high-frequency chain microinverter. Moreover, the voltage transformation ratio of the high-frequency chain microinverter can be adjusted by regulating the duty cycle of the energy storage switch, achieving adjustable gain of the high-frequency chain microinverter.

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

[0055] Specifically, Figure 6 The example shows a buck-boost circuit 30 including a buck-boost circuit, and a transformer module 20 being a two-winding transformer. The first terminal of the buck-boost circuit is connected to the secondary winding N of the transformer module 20. S The first terminal is connected, and the second terminal of the buck-boost circuit is connected to the secondary winding N of the transformer module. S The second terminal is connected. When the second AC signal is in its positive half-cycle, the buck-boost circuit can be controlled into an energy storage phase, allowing it to store the energy generated during the positive half-cycle of the second AC signal. When the second AC signal is in its negative half-cycle, the buck-boost circuit can be controlled into a discharge phase, discharging the stored energy. At this time, the ratio of the buck-boost circuit's discharge voltage to the voltage of the second AC signal during its positive half-cycle is adjusted according to the duty cycle of the energy storage phase, thus extending the range of this ratio from the output voltage of the high-frequency chain-type micro-inverter to the voltage of the second AC signal during its positive half-cycle to nV. in This allows for the increase of the gain of the high-frequency chain micro-inverter through the buck-boost circuit, thus enabling the gain of the high-frequency chain micro-inverter to be adjustable.

[0056] Alternatively, when the second AC signal is in its negative half-cycle, the buck-boost circuit can be controlled into an energy storage phase, allowing it to store the energy generated during the negative half-cycle of the second AC signal. When the second AC signal is in its positive half-cycle, the buck-boost circuit can be controlled into a discharge phase, discharging the stored energy. In this case, the ratio of the buck-boost circuit's discharge voltage to the voltage during the negative half-cycle of the second AC signal is adjusted according to the duty cycle of the energy storage phase. This allows the ratio of the high-frequency chain-type micro-inverter's output voltage to the voltage during the negative half-cycle of the second AC signal to be extended to nV. in Similarly, the gain of the high-frequency chain micro-inverter can be increased, thus realizing the adjustable gain of the high-frequency chain micro-inverter.

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

[0058] Specifically, such as Figure 6 As shown, when the first switching unit 301 is turned on and the second switching unit 302 is turned off, the first switching unit 301 and the first inductor L... f and secondary winding N S To form an energy storage circuit, the first inductor L f It can store the secondary winding N S The supplied electrical energy. When the first switching unit 301 is turned off and the second switching unit 302 is turned on, the second switching unit 302 and the first inductor L... f and the first capacitor C f Forming a discharge circuit, making the first inductor L f Power is supplied through the output terminal VOUT of the high-frequency chain-type micro-inverter. The ratio of the on-time of the first switching unit 301 to the duty cycle of the buck-boost circuit is the duty cycle of the first switching unit 301. Since the second AC signal is an AC signal, the duty cycle of the first switching unit 301 is less than or equal to 0.5. This makes the first inductor L... f Discharge voltage v out The range is less than or equal to the secondary winding N S Provided voltage nV in This allows for a significant increase in the output voltage of the high-frequency chain-type microinverter compared to related technologies, reducing the turns ratio requirement of the transformer module 20. This, in turn, reduces efficiency losses caused by parasitic parameters of the transformer module 20, thereby increasing the efficiency of the high-frequency chain-type microinverter. Furthermore, the gain of the high-frequency chain-type microinverter can be adjusted by regulating the duty cycle of the first switching unit 301, achieving adjustable gain.

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

[0060] Specifically, the first secondary-side switch Q1 and the second secondary-side switch Q2 can be connected back-to-back in series, and the third secondary-side switch Q3 and the fourth secondary-side switch Q4 can also be connected back-to-back in series. By setting the first secondary-side switch Q1 and the second secondary-side switch Q2 to be connected back-to-back, and the third secondary-side switch Q3 and the fourth secondary-side switch Q4 to be connected back-to-back, the high-frequency chain-type micro-inverter gains reactive power support capability. This also facilitates commutation in the buck-boost circuit, optimizes the current path of the buck-boost circuit, and improves the efficiency of the buck-boost circuit.

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

[0062] Specifically, Figure 6 The example shown is an inverter circuit 10, which is a half-bridge inverter circuit. When the first primary-side switch T1 is turned on and the second primary-side switch T2 is turned off, the voltage supplied by the DC power supply terminal VIN passes through the positive terminal + of the DC power supply terminal VIN, through the first primary-side switch T1, and then through the primary winding N. p The second end M2 flows to the primary winding N.p The first terminal M1 is connected to the first pole of the third capacitor C3, and then transmitted through the third capacitor C3 to the negative terminal of the DC power supply VIN. At this time, the primary winding N... p The voltage is such that the second terminal M2 is positive and the first terminal M1 is negative. When the first primary-side switch T1 is off and the second primary-side switch T2 is on, the voltage at the second terminal of the second capacitor C2 is supplied by the primary winding N. p The first end M1 flows to the primary winding N p The second terminal M2 is transmitted to the negative terminal of the DC power supply VIN through the second primary-side switch T2. At this time, the primary winding N... p The voltage is set so that the first terminal M1 is positive and the second terminal M2 is negative. This enables the inversion of the DC signal provided by the DC power supply terminal VIN.

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

[0064] Specifically, Figure 7 The inverter circuit 10 is illustrated as a full-bridge inverter circuit. When the third primary-side switch T3 and the sixth primary-side switch T6 are turned on, and the fourth primary-side switch T4 and the fifth primary-side switch T5 are turned off, the voltage supplied by the DC power supply terminal VIN passes through the positive terminal + of the DC power supply terminal VIN, through the third primary-side switch T3, and then through the primary winding N. p The first end M1 flows to the primary winding N p The second terminal M2 is transmitted to the negative terminal of the DC power supply VIN through the sixth primary-side switch T6. At this time, the primary winding N... p The voltage is such that the first terminal M1 is positive and the second terminal M2 is negative. When the third primary-side switch T3 and the sixth primary-side switch T6 are turned off, and the fourth primary-side switch T4 and the fifth primary-side switch T5 are turned on, the voltage supplied by the DC power supply terminal VIN passes through the positive terminal + of the DC power supply terminal VIN, through the fourth primary-side switch T4, and then through the primary winding N. p The second end M2 flows to the primary winding N.p The first terminal M1 is connected to the negative terminal of the DC power supply VIN via the fifth primary-side switch T5. At this time, the primary winding N... p The voltage is set so that the second terminal M2 is positive and the first terminal M1 is negative. This enables the inversion of the DC signal provided by the DC power supply terminal VIN.

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

[0066] Specifically, Figure 8 The example shown is a push-pull inverter circuit 10. When the seventh primary-side switch T7 is turned on and the eighth primary-side switch T8 is turned off, the voltage supplied 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 portion from the center tap M0 to the first terminal M1 is transmitted to the negative terminal of the DC power supply VIN via the seventh primary-side switch T7. At this time, the primary winding N... p The voltage is positive at the center tap M0 and negative at the first tap M1. When the seventh primary-side switch T7 is turned off and the eighth primary-side switch T8 is turned on, the voltage supplied by the DC power supply terminal VIN flows from the positive terminal of VIN through the primary winding N. p The portion from the center tap M0 to the second terminal M2 is transmitted to the negative terminal of the DC power supply VIN via the eighth primary-side switch transistor T8. At this time, the primary winding N... p The voltage is set with the center tap M0 being positive and the second tap M2 being negative. This enables the inversion of the DC signal supplied by the DC power supply terminal VIN.

[0067] It should be noted that, Figures 6 to 8 This is merely an example illustrating some circuit types of the inverter circuit 10. In other embodiments, the inverter circuit 10 can be any high-frequency AC square wave generator. Furthermore, the inverter circuit 10 may also include other types of circuits. For example, the inverter circuit 10 may include at least two stages of circuitry, with each stage including a buck-boost circuit and an inverter circuit. Components may be shared between different stages of circuitry; this is not a limitation.

[0068] Figure 9 This is a schematic diagram of another high-frequency chain-type microinverter provided in an embodiment of the present invention. Figure 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 of the second AC signal.

[0069] Specifically, such as Figure 9 As shown, when the buck-boost circuit 30 includes two buck-boost circuits, the two buck-boost circuits can be connected in phases. That is, each buck-boost circuit has the same connection method, and the output terminal of each buck-boost circuit serves as a single-phase output terminal of the high-frequency chain micro-inverter. When the single-phase output terminal of the high-frequency chain micro-inverter is connected to the load, different single-phase output terminals can be connected to different or the same loads to supply power to the load. Moreover, the single-phase output terminal of the high-frequency chain micro-inverter can be connected to the power grid to realize 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, one buck-boost circuit can be controlled to perform buck-boost conversion on the second AC signal during the positive half-cycle of the second AC signal, and the other buck-boost circuit can perform buck-boost conversion on the second AC signal during 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, such as Figure 9 As shown, the two buck-boost circuits are the first buck-boost circuit 31 and the second buck-boost circuit 32, respectively. The first buck-boost circuit 31 includes a first first switching unit 311, a first second switching unit 312, and a first first inductor L. f1 and the first capacitor C f1 The first switching unit 311 includes a first secondary-side switch Q11 and a first secondary-side switch Q21, and the second switching unit 312 includes a first third secondary-side switch Q31 and a first fourth secondary-side switch Q41; their specific connection method is the same as that of a buck-boost circuit, and the first capacitor C... f1 The first terminal serves as the first single-phase output terminal VOUT1 of the high-frequency chain-type microinverter. The second buck-boost circuit 32 includes a second first switching unit 321, a second second switching unit 322, and a second first inductor L. f2 and the second first capacitor C f2The second first switching unit 321 includes a second first secondary-side switching transistor Q12 and a second second secondary-side switching transistor Q22, and the second second switching unit 312 includes a second third secondary-side switching transistor Q32 and a second fourth secondary-side switching transistor Q42; their specific connection method is the same as that of a buck-boost circuit, and the second first capacitor C f2 The first pole serves as the second single-phase output terminal VOUT2 of the high-frequency chain-type micro-inverter. During operation, during the positive half-cycle of the second AC signal, the first primary secondary switch Q11, the first secondary secondary switch Q21, the second secondary secondary switch Q32, and the second secondary secondary switch Q42 can be turned on, while the first secondary secondary switch Q31, the first secondary secondary switch Q41, the second primary secondary switch Q12, and the second secondary secondary switch Q22 are turned off. At this time, the 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 occurs through the second third secondary-side switch Q32 and the second fourth secondary-side switch Q42. During the negative half-cycle of the second AC signal, the first first secondary-side switch Q11 and the first second secondary-side switch Q21, as well as the second third secondary-side switch Q32 and the second fourth secondary-side switch Q42, can be turned off, while the first third secondary-side switch Q31 and the first fourth secondary-side switch Q41, as well as the second first secondary-side switch Q12 and the second second secondary-side switch Q22, are 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 electrical energy of the negative half-cycle of the second AC signal. f1 Discharge is achieved through the first third secondary-side switch Q31 and the first fourth secondary-side switch Q41. This allows for buck-boost conversion of the second AC signal throughout its entire cycle, improving the utilization rate of the second AC signal and consequently increasing the efficiency of the high-frequency chain-type micro-inverter.

[0071] It should be noted that, Figure 9 The example shown illustrates an inverter circuit 10 as a half-bridge inverter circuit. In other embodiments, inverter circuit 10 can also be a full-bridge inverter circuit or a push-pull inverter circuit. Figure 10 This is a schematic diagram of another high-frequency chain-type microinverter provided in an embodiment of the present invention. Figure 10 As shown, inverter circuit 10 and Figure 7 The provided inverter circuit 10 is the same, both being full-bridge inverter circuits. Figure 11This is a schematic diagram of another high-frequency chain-type microinverter provided in an embodiment of the present invention. Figure 11 As shown, inverter circuit 10 and Figure 8 The provided inverter circuit 10 is the same, and is a push-pull inverter circuit.

[0072] In some embodiments, Figure 12 This is a schematic diagram of another high-frequency chain-type microinverter provided in an embodiment of the present invention. Figure 12 As shown, the secondary winding N S Including the first secondary winding N S1 Second secondary winding N S2 The first terminals of the two buck-boost circuits are respectively connected to the first secondary winding N. S1 The first and second secondary windings N S2 The first end is connected, and the first secondary winding N S1 The second end and the second secondary winding N S2 The second terminal is grounded to n, and the second terminal of each buck-boost circuit is connected to the first secondary winding N. S1 The second end is connected; wherein, the first secondary winding N S1 The first and second secondary windings N S2 The first end is the same name end.

[0073] Specifically, transformer module 20 can be a single three-winding high-frequency transformer, with 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 Second secondary winding N S2 The first terminal of the first buck-boost circuit 31 is connected to the first secondary winding N. S1 The first terminal is connected, and the first terminal of the second buck-boost circuit 32 is connected to the second secondary winding N. S2 The first terminal is connected, and the second terminal of the first buck-boost circuit 31 and the second terminal of the second buck-boost circuit 32 are grounded. At this time, by controlling the operating states of the two buck-boost circuits, the buck-boost conversion of the second AC signal is achieved, enabling the two buck-boost circuits to output in separate phases. The control of the operating states of the two buck-boost circuits is related to... Figures 9 to 11 The control process is similar and will not be described in detail here.

[0074] In some embodiments, the transformer module may include a first transformer and a second transformer. The inverter circuit is 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 are respectively connected to two buck-boost circuits, which can also realize the phase-by-phase output after the buck-boost transformation of the second AC signal.

[0075] This invention also provides a photovoltaic power generation system. This photovoltaic power generation system includes the high-frequency chain-type microinverter provided in any embodiment of this invention. Since the photovoltaic power generation system includes the high-frequency chain-type microinverter provided in any embodiment of this invention, it has the same beneficial effects as the high-frequency chain-type microinverter provided in any embodiment of this invention, and will not be described again here.

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

Claims

1. A high-frequency chain-type micro inverter, characterized in that, Includes inverter circuit, transformer module and buck-boost circuit; The input terminal of the inverter circuit is connected to the DC power supply terminal, the output terminal 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 terminal of the buck-boost circuit serves as the output terminal of the high-frequency chain-type micro inverter. The inverter circuit is used to invert the DC signal provided by the DC power supply terminal to form a first AC signal. The transformer module is used to boost the first AC signal to form a second AC signal. The buck-boost circuit is used to buck-boost the second AC signal to form a sinusoidal signal. The buck-boost circuit includes at least one buck-boost circuit; The first terminal of the buck-boost circuit is connected to the first terminal of the secondary winding of the transformer module, the output terminal of the buck-boost circuit serves as the output terminal of the high-frequency chain micro inverter, and the second terminal of the buck-boost circuit is connected to the second terminal of the secondary winding of the transformer module; the buck-boost circuit is used to perform buck-boost conversion on the half-cycle signal of the second AC signal.

2. The high-frequency chain-type micro inverter according to claim 1, characterized in that, The buck-boost circuit includes a first switching unit, a second switching unit, a first capacitor, and a first inductor; The first end of the first switching unit is connected to the first end of the secondary winding of the transformer module. The second end of the first switching unit is connected to the first end of the first inductor and the first end of the second switching unit. The second end of the second switching unit is connected to the first terminal of the first capacitor and serves as the output terminal of the high-frequency chain micro inverter. The second end of the first inductor and the second terminal of the first capacitor are connected to the second end of the secondary winding of the transformer module. The first switching unit and the second switching unit are turned on in a time-sharing manner.

3. The high-frequency chain-type micro inverter according to claim 2, characterized in that, The first switching unit includes a first secondary-side switching transistor and a second secondary-side switching transistor, and the second switching unit includes a third secondary-side switching transistor and a fourth secondary-side switching transistor; The first terminal of the first secondary-side switching transistor is connected to the first end of the secondary winding of the transformer module; the second terminal of the first secondary-side switching transistor is connected to the second terminal of the second secondary-side switching transistor; the first terminal of the second secondary-side switching transistor is connected to the first terminal of the third secondary-side switching transistor and the first end of the first inductor; the second terminal of the third secondary-side switching transistor is connected to the second terminal of the fourth secondary-side switching transistor; and the first terminal of the fourth secondary-side switching transistor is connected to the first terminal of the first capacitor. The first and second secondary-side switching transistors are synchronously turned on or off, and the third and fourth secondary-side switching transistors are synchronously turned on or off.

4. The high-frequency chain-type microinverter according to any one of claims 1-3, characterized in that, When the buck-boost circuit includes two buck-boost circuits, the two buck-boost circuits are used to perform buck-boost conversion on at least one half-cycle of the second AC signal.

5. The high-frequency chain-type microinverter according to claim 4, characterized in that, The secondary winding includes a first secondary winding and a second secondary winding; The first terminals of the two buck-boost circuits are respectively connected to the first terminal of the first secondary winding and the first terminal of the second secondary winding. The second terminals of the first secondary winding and the second secondary winding are grounded. The second terminal of each buck-boost circuit is connected to the second terminal of the first secondary winding. The first terminals of the first secondary winding and the second secondary winding are terminals with the same name.

6. The high-frequency chain-type micro inverter according to claim 1, characterized in that, The inverter circuit includes a first primary-side switch, a second primary-side switch, a second capacitor, and a third capacitor; The first terminal of the first primary-side switching transistor and the first terminal of the second capacitor are connected to the positive terminal of the DC power supply. The second terminal of the first primary-side switching transistor is connected to the first terminal of the second primary-side switching transistor and is connected to the second terminal of the primary winding. The second terminal of the second capacitor is connected to the first terminal of the third capacitor and is connected to the first terminal of the primary winding. The second terminal of the third capacitor and the second terminal of the second primary-side switching transistor are connected to the negative terminal of the DC power supply.

7. The high-frequency chain-type micro inverter according to claim 1, characterized in that, The inverter circuit includes a third primary-side switch, a fourth primary-side switch, a fifth primary-side switch, and a sixth primary-side switch; The first poles of the third primary-side switch and the fourth primary-side switch are connected to the positive terminal of the DC power supply. The second pole of the third primary-side switch is connected to the first pole of the fifth primary-side switch and to the first terminal of the primary winding. The second pole of the fourth primary-side switch is connected to the first pole of the sixth primary-side switch and to the second terminal of the primary winding. The second poles of the fifth and sixth primary-side switches are connected to the negative terminal of the DC power supply.

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

9. A photovoltaic power generation system, characterized in that, Including the high-frequency chain-type microinverter as described in any one of claims 1-8.

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