Circuit topology of micro inverter, and control method

Abstract

The present application relates to the technical field of micro inverters, and relates to a circuit topology of a micro inverter, and a control method. One specific implementation of the method comprises: measuring the maximum power value of a photovoltaic module, and receiving a current input by the photovoltaic module; acquiring a power grid voltage value in an alternating-current power grid, determining, on the basis of the power grid voltage value and the maximum power value of the photovoltaic module, a sine wave period corresponding to an output current, and on the basis of the sine wave period, controlling on and off of a plurality of switch transistors in a resonance circuit and a voltage doubling rectifying circuit in the micro inverter, so as to respectively form a conduction current loop in the resonance circuit and form an induction current loop in the voltage doubling rectifying circuit; and transmitting the sinusoidal output current to the alternating current power grid by means of the output end of the voltage doubling rectifying circuit. The implementation implements a control strategy for first-stage power conversion of the micro inverter, improves the efficiency of the micro inverter, increases the power of the micro inverter, and reduces the cost of the micro inverter.

Description

Circuit topology and control method of micro inverter Technical Field

[0001] The present application relates to the technical field of micro inverters, and in particular to a circuit topology and control method of a micro inverter. Background Art

[0002] Microinverters help minimize damage to photovoltaic panel panels and reduce the impact of inverter failures on photovoltaic grid-connected power generation systems. Compared with centralized inverters, they offer high reliability and lower power generation costs, making them suitable for a wide range of applications. However, current microinverter circuit topologies are primarily flyback circuits, which are limited by the size of the transformer core and switching frequency, resulting in low power and efficiency. Although related technologies have employed a two-stage power conversion topology to improve the power and efficiency of microinverters, this still struggles to meet the demands of high-power photovoltaic modules and increases the cost of microinverters.

[0003] Currently, no effective solution has been proposed to solve the problems of low efficiency and power as well as high cost of micro-inverters caused by the two-stage power conversion control strategy adopted by micro-inverters in related technologies.

[0004] Summary of the Invention

[0005] The circuit topology and control method of a micro-inverter provided by the embodiments of the present invention at least solve the problems of low efficiency and power and high cost of micro-inverters caused by the use of a two-stage power conversion control strategy in related technologies.

[0006] In order to solve the above problems, one aspect of an embodiment of the present invention provides a circuit topology of a micro inverter, including a resonant circuit, a winding transformer and a voltage doubler rectifier circuit, wherein:

[0007] A resonant circuit is connected to the primary winding of the winding transformer, and an input end of the resonant circuit is connected to the photovoltaic module for receiving current input by the photovoltaic module;

[0008] A voltage-doubling rectifier circuit includes a switch bridge arm and a capacitor bridge arm connected in parallel. The voltage-doubling rectifier circuit is connected to the secondary winding of a winding transformer. The induced current generated by the secondary winding flows through the capacitor in the capacitor bridge arm to form an induced current loop and achieve a multiple voltage boost. The output end of the voltage-doubling rectifier circuit is used to transmit a sinusoidal output current to the AC power grid.

[0009] In some embodiments, when the resonant circuit is a full-bridge resonant circuit, it includes: a first bridge arm, a second bridge arm and an LLC circuit; wherein the first bridge arm and the second bridge arm are connected in parallel, the first bridge arm includes a first switch tube and a second switch tube connected in series, and the second bridge arm includes a third switch tube and a fourth switch tube connected in series; the LLC circuit includes a leakage inductance, an excitation inductance and a resonant capacitor connected in series, one end of the LLC circuit is connected to the midpoint of the first bridge arm, and the other end of the LLC circuit is connected to the midpoint of the second bridge arm.

[0010] In some embodiments, when the sinusoidal wave period corresponding to the output current is the positive half period of the sinusoidal wave, when the first switch tube and the fourth switch tube are turned on, the current input by the photovoltaic component forms a first conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit. The fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a first induced current loop in the voltage doubler rectifier circuit; wherein, the first conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the first induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in the capacitor bridge arm in sequence.

[0011] In some embodiments, when the first switch tube and the fourth switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third switch tube and the second switch tube are turned on to form a second conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit, the seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a second induced current loop in the voltage doubler rectifier circuit; wherein, the resonant cavity current in the second conduction current loop passes through the parasitic diode of the third switch tube, the first capacitor, the parasitic diode of the second switch tube, and the LLC circuit in sequence; the induced current in the second induced current loop passes through the third capacitor in the capacitor bridge arm, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence.

[0012] In some embodiments, after the resonant cavity current is zero, the photovoltaic component inputs current to the resonant circuit through the first capacitor on the DC side bus to form a third conduction current loop, and generates an induced current in the voltage doubler rectifier circuit, and the induced current forms a third induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the third conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the third induced current loop passes through the third capacitor, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence.

[0013] In some embodiments, when the third switch tube and the second switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the first switch tube and the fourth switch tube are turned on to form a fourth conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit, the fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a fourth induced current loop in the voltage doubler rectifier circuit; wherein, the current in the fourth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the fourth induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in sequence.

[0014] In some embodiments, when the sinusoidal wave period corresponding to the output current is the negative half-cycle of the sinusoidal wave, when the first switch tube and the fourth switch tube are turned on, the current input by the photovoltaic component forms a fifth conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit. The seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a fifth induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the fifth conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the induced current in the fifth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in the capacitor bridge arm in sequence.

[0015] In some embodiments, when the first and fourth switching tubes are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third and second switching tubes are turned on to form a sixth conduction current loop in the resonant circuit, and an induced current is generated in the voltage doubler rectifier circuit. The fifth and sixth switching tubes in the voltage doubler rectifier circuit are turned on, and the induced current forms a sixth induced current loop in the voltage doubler rectifier circuit; wherein, the resonant cavity current in the sixth conduction current loop passes through the parasitic diode of the second switching tube, the LLC circuit, the parasitic diode of the third switching tube, and the first capacitor in sequence; and the induced current in the sixth induced current loop passes through the second capacitor in the capacitor bridge arm, the MOS tube of the fifth switching tube, and the parasitic diode of the sixth switching tube in sequence.

[0016] In some embodiments, after the resonant cavity current is zero, the current input by the photovoltaic component forms a seventh conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit, and the induced current forms a seventh induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the seventh conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the seventh induced current loop passes through the second capacitor, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence.

[0017] In some embodiments, when the third switch tube and the second switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the first switch tube and the fourth switch tube in the resonant circuit are turned on to form an eighth conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit, the seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms an eighth induced current loop in the voltage doubler rectifier circuit; wherein, the current in the eighth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the eighth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in sequence.

[0018] In some embodiments, when the resonant circuit is a symmetrical half-bridge resonant circuit, it includes: a first bridge arm and an LLC circuit; wherein the first bridge arm includes a first switching tube and a second switching tube connected in series; the LLC circuit includes a resonant capacitor bridge arm, and an inductance circuit composed of a leakage inductance and an excitation inductance connected in series, the resonant capacitor bridge arm is connected in parallel with the first bridge arm, the resonant capacitor bridge arm includes a first resonant capacitor and a second resonant capacitor connected in series, one end of the inductance circuit composed of the leakage inductance and the excitation inductance connected in series is connected to the midpoint of the first bridge arm, and the other end of the inductance circuit composed of the leakage inductance and the excitation inductance connected in series is connected to the midpoint of the resonant capacitor bridge arm.

[0019] In some embodiments, when the resonant circuit is an asymmetric half-bridge resonant circuit, it includes: a first bridge arm and an LLC circuit; wherein the first bridge arm includes a first switching tube and a second switching tube connected in series; the LLC circuit includes a leakage inductance, an excitation inductance and a resonant capacitor connected in series, one end of the LLC circuit is connected to the midpoint of the first bridge arm, and the other end of the LLC circuit is connected to the negative terminal of the first bridge arm.

[0020] In some embodiments, the switch bridge arm includes an upper switch bridge arm and a lower switch bridge arm; wherein the upper switch bridge arm includes a fifth switch tube and a sixth switch tube connected in series and arranged in a mirror image, and the lower switch bridge arm includes a seventh switch tube and an eighth switch tube connected in series and arranged in a mirror image.

[0021] In some embodiments, the capacitor bridge arm includes a second capacitor and a third capacitor connected in series; one end of the secondary winding is connected to the midpoint of the switch bridge arm, and the other end of the secondary winding is connected to the midpoint of the capacitor bridge arm.

[0022] In some embodiments, the capacitor bridge arm includes multiple capacitor sub-bridge arms connected in parallel, the first capacitor sub-bridge arm among the multiple capacitor sub-bridge arms includes a second capacitor and a third capacitor connected in series, one end of the secondary winding is connected to the midpoint of the switch bridge arm, and the other end of the secondary winding is connected to the midpoint of the first capacitor sub-bridge arm.

[0023] In some embodiments, at least one filter inductor is provided at the output end of the voltage doubler rectifier circuit.

[0024] In some embodiments, a common-mode inductor is provided at the output end of the voltage doubler rectifier circuit.

[0025] In order to solve the above problem, one aspect of an embodiment of the present invention provides a micro inverter, comprising a controller and any one of the above circuit topologies;

[0026] The controller is used to output a drive signal to control the switching state of multiple switching tubes in the circuit topology, so that the circuit topology can transmit a sinusoidal output current to the AC power grid through a first-level power conversion.

[0027] To solve the above problem, one aspect of an embodiment of the present invention provides a control method for a micro-inverter, wherein the micro-inverter adopts any of the above circuit topologies; the control method includes:

[0028] Detect the maximum power value of the photovoltaic module and receive the current input by the photovoltaic module;

[0029] Obtaining the grid voltage value in the AC grid, determining the sinusoidal wave period corresponding to the output current based on the grid voltage value and the maximum power value of the photovoltaic module, and controlling the on and off of multiple switching tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter based on the sinusoidal wave period, so as to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively;

[0030] The output current of the sine wave is transmitted to the AC power grid through the output end of the voltage doubler rectifier circuit.

[0031] In some embodiments, the steps of controlling the on and off of a plurality of switching tubes in a resonant circuit and a voltage doubler rectifier circuit in a micro-inverter according to a sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, include:

[0032] Determine the positive half-cycle and negative half-cycle of the sine wave corresponding to the sine wave cycle of the output current, and alternately control the on and off of multiple switching tubes in the micro inverter according to the positive half-cycle and negative half-cycle of the sine wave to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively.

[0033] In some embodiments, the step of obtaining a grid voltage value in an AC grid and determining a sine wave period corresponding to an output current according to the grid voltage value and a maximum power value of a photovoltaic module includes:

[0034] Obtaining a grid voltage value in the AC grid, and determining an output current value based on the grid voltage value and a maximum power value of the photovoltaic module;

[0035] If the current value is greater than 0, it is determined that the sine wave corresponding to the output current is in the positive half cycle of the sine wave; if the current value is less than 0, it is determined that the sine wave corresponding to the output current is in the negative half cycle of the sine wave; wherein, the sine wave frequency of the output current is consistent with the sine wave frequency of the AC power in the AC power grid.

[0036] In some embodiments, the steps of controlling the on and off of multiple switching tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, include:

[0037] Control the on and off of multiple switching tubes in the resonant circuit, and the current input by the photovoltaic module and the resonant cavity current in the resonant circuit flow through the turned-on switching tube to form a flipped conduction current loop, and generate an induced current in the voltage doubler rectifier circuit. Control the on and off of multiple switching tubes in the voltage doubler rectifier circuit so that the induced current flows through the target capacitor of the voltage doubler rectifier circuit to form a corresponding induced current loop.

[0038] In some embodiments, when the current source in the conduction current loop and the switch tube in the resonant circuit through which the conduction current flows are the same, in the positive half cycle of the sine wave and the negative half cycle of the sine wave, the target capacitance through which the induced current flows in the induced current loop corresponding to the conduction current loop is different; wherein the target capacitance includes the second capacitor and the third capacitor in the capacitance bridge arm of the voltage doubler rectifier circuit.

[0039] In some embodiments, the steps of controlling the on and off of a plurality of switching tubes in a resonant circuit and a voltage doubler rectifier circuit in a micro-inverter according to a sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, include:

[0040] If the sine wave cycle is the positive half cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the first switching tube and the fourth switching tube in the resonant circuit are controlled to be turned on, the current input by the photovoltaic component forms a first conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit. The fifth switching tube and the sixth switching tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm of the voltage doubler rectifier circuit to form a first induced current loop; wherein, the current input by the photovoltaic component in the first conduction current loop passes through the MOS tube of the first switching tube, the LLC circuit, the MOS tube of the fourth switching tube, and the first capacitor on the DC side bus in sequence; and the induced current in the first induced current loop passes through the MOS tube of the sixth switching tube, the parasitic diode of the fifth switching tube, and the second capacitor in sequence.

[0041] In some embodiments, if the sine wave period is the positive half cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the first switching tube and the fourth switching tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit is fed to the first capacitor on the DC side bus, the third switching tube and the second switching tube in the resonant circuit are controlled to be turned on to form a second conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit. The seventh switching tube and the eighth switching tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the third capacitor in the capacitor bridge arm to form a second induced current loop; wherein, the resonant cavity current in the second conduction current loop passes through the parasitic diode of the third switching tube, the first capacitor, the parasitic diode of the second switching tube, and the LLC circuit in sequence; and the induced current in the second induced current loop passes through the third capacitor, the MOS tube of the eighth switching tube, and the parasitic diode of the seventh switching tube in sequence.

[0042] In some embodiments, if the sine wave period is the positive half cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the current in the resonant cavity is zero, the photovoltaic component inputs current to the resonant circuit through the first capacitor on the DC side bus to form a third conduction current loop, and generates an induced current in the voltage doubler rectifier circuit. The induced current flows through the third capacitor in the capacitor bridge arm to form a third induced current loop; wherein, the current input by the photovoltaic component in the third conduction current loop passes through the MOS tube of the third switching tube, the LLC circuit, the MOS tube of the second switching tube, and the first capacitor in sequence, and the induced current in the third induced current loop passes through the third capacitor, the MOS tube of the eighth switching tube, and the parasitic diode of the seventh switching tube in sequence.

[0043] In some embodiments, if the sine wave period is the positive half cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the third switching tube and the second switching tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit is fed to the first capacitor on the DC side bus, the first switching tube and the fourth switching tube are controlled to be turned on to form a fourth conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit. The fifth switching tube and the sixth switching tube are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm to form a fourth induced current loop; wherein, the current in the fourth conduction current loop passes through the parasitic diode of the fourth switching tube, the LLC circuit, the parasitic diode of the first switching tube, and the first capacitor in sequence, and the induced current in the fourth induced current loop passes through the MOS tube of the sixth switching tube, the parasitic diode of the fifth switching tube, and the second capacitor in sequence.

[0044] In some embodiments, the steps of controlling the on and off of a plurality of switching tubes in a resonant circuit and a voltage doubler rectifier circuit in a micro-inverter according to a sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, include:

[0045] If the sine wave cycle is the negative half cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are controlled according to the frequency of the sine wave; when the first switching tube and the fourth switching tube in the resonant circuit are controlled to be turned on, the current input by the photovoltaic component forms a fifth conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit, and the seventh switching tube and the eighth switching tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the third capacitor in the capacitor bridge arm to form a fifth induced current loop; wherein, the current input by the photovoltaic component in the fifth conduction current loop passes through the MOS tube of the first switching tube, the LLC circuit, the MOS tube of the fourth switching tube, and the first capacitor on the DC side bus in sequence; the induced current in the fifth induced current loop passes through the MOS tube of the seventh switching tube, the parasitic diode of the eighth switching tube, and the third capacitor in sequence.

[0046] In some embodiments, if the sine wave period is the negative half-cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are controlled according to the frequency of the sine wave; when the first switching tube and the fourth switching tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third switching tube and the second switching tube in the resonant circuit are controlled to be turned on to form a sixth conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit, the fifth switching tube and the sixth switching tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm to form a sixth induced current loop; wherein, the resonant cavity current in the sixth conduction current loop passes through the parasitic diode of the second switching tube, the LLC circuit, the parasitic diode of the third switching tube, and the first capacitor in sequence; and the induced current in the sixth induced current loop passes through the second capacitor, the MOS tube of the fifth switching tube, and the parasitic diode of the sixth switching tube in sequence.

[0047] In some embodiments, if the sine wave period is the negative half-cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are controlled according to the frequency of the sine wave; when the current in the resonant cavity is zero, the current input by the photovoltaic component forms a seventh conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, and the induced current flows through the second capacitor of the capacitor bridge arm to form a seventh induced current loop; wherein, the current input by the photovoltaic component in the seventh conduction current loop passes through the MOS tube of the third switching tube, the LLC circuit, the MOS tube of the second switching tube, and the first capacitor in sequence, and the induced current in the seventh induced current loop passes through the second capacitor, the MOS tube of the fifth switching tube, and the parasitic diode of the sixth switching tube in sequence.

[0048] In some embodiments, if the sine wave period is the negative half-cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are controlled according to the frequency of the sine wave; when the third switching tube and the second switching tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit is fed to the first capacitor on the DC side bus, the first switching tube and the fourth switching tube are controlled to be turned on to form an eighth conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit, the seventh switching tube and the eighth switching tube are controlled to be turned on, and the induced current flows through the third capacitor of the capacitor bridge arm to form an eighth induced current loop; wherein, the current in the eighth conduction current loop passes through the parasitic diode of the fourth switching tube, the LLC circuit, the parasitic diode of the first switching tube, and the first capacitor in sequence, and the induced current in the eighth induced current loop passes through the MOS tube of the seventh switching tube, the parasitic diode of the eighth switching tube, and the third capacitor in sequence.

[0049] In some embodiments, the operating state of the multiple switch tubes is a soft switching state.

[0050] In order to solve the above problems, one aspect of an embodiment of the present invention provides a micro inverter, including: a processor, and a memory for storing a program, characterized in that the program includes instructions, which, when executed by the processor, enable the processor to execute any of the above-mentioned micro inverter control methods.

[0051] In order to solve the above problem, one aspect of an embodiment of the present invention provides a non-transitory machine-readable medium storing computer instructions, wherein the computer instructions are used to enable a computer to execute any of the above-mentioned micro-inverter control methods.

[0052] The beneficial effects of the embodiments of the present invention are as follows: by detecting the maximum power value of the photovoltaic module and receiving the current input by the photovoltaic module; obtaining the grid voltage value in the AC power grid, determining the sinusoidal wave period corresponding to the output current according to the grid voltage value and the maximum power value of the photovoltaic module, and controlling the conduction and shutdown of multiple switching tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter according to the sinusoidal wave period, so as to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively; the technical means of transmitting the sinusoidal output current to the AC power grid through the output end of the voltage doubler rectifier circuit overcomes the problems of low efficiency and power and high cost of the micro-inverter caused by the use of a two-stage power conversion control strategy in the related art, and realizes the function of the micro-inverter outputting sinusoidal AC power grid-connected through only one-stage power conversion, effectively improving the power and efficiency of the micro-inverter, expanding the applicable scenarios of the micro-inverter, and reducing the cost of the micro-inverter due to the reduction of the device layout required for the multi-stage power conversion topology.

[0053] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below so that other features, objects, and advantages of the invention are more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be derived from these drawings without inventive effort.

[0055] FIG1 is a schematic diagram of a circuit topology of a micro inverter according to an embodiment of the present invention.

[0056] FIG2 is a schematic diagram of a circuit topology of a micro inverter according to another embodiment of the present invention.

[0057] FIG3 is a schematic diagram of a circuit topology of a micro inverter according to yet another embodiment of the present invention.

[0058] FIG4 is a schematic diagram of a circuit topology of a micro inverter according to yet another embodiment of the present invention.

[0059] FIG5 is a schematic diagram of a circuit topology of a micro inverter according to yet another embodiment of the present invention.

[0060] FIG6 is a schematic diagram of a circuit topology of a micro inverter according to yet another embodiment of the present invention.

[0061] FIG7 is a flow chart of a method for controlling a micro-inverter according to an embodiment of the present invention.

[0062] FIG8 a is a schematic diagram of current flows in the first conduction current loop and the first induction current loop during the positive half cycle of the sinusoidal wave in the control method shown in FIG7 ;

[0063] FIG8 b is a schematic diagram of current flows in the second conduction current loop and the second induction current loop during the positive half cycle of the sine wave in the control method shown in FIG7 ;

[0064] FIG8 c is a schematic diagram of current flows in the third conduction current loop and the third induction current loop during the positive half cycle of the sinusoidal wave in the control method shown in FIG7 ;

[0065] FIG8 d is a schematic diagram of current flows in the fourth conduction current loop and the fourth induction current loop during the positive half cycle of the sinusoidal wave in the control method shown in FIG7 ;

[0066] FIG8e is a schematic diagram of current flow directions of the fifth conduction current loop and the fifth induction current loop during the negative half cycle of the sine wave in the control method shown in FIG7 ;

[0067] FIG8 f is a schematic diagram of current flow directions of the sixth conduction current loop and the sixth induction current loop during the negative half cycle of the sine wave in the control method shown in FIG7 ;

[0068] 8g is a schematic diagram of current flow directions of the seventh conduction current loop and the seventh induction current loop during the negative half cycle of the sine wave in the control method shown in FIG7 ;

[0069] FIG8h is a schematic diagram showing the current flow directions of the eighth conduction current loop and the eighth induction current loop during the negative half cycle of the sine wave in the control method shown in FIG7 .

[0070] FIG9 is a schematic structural diagram of the electronic device of this embodiment. DETAILED DESCRIPTION

[0071] The following describes embodiments of the present invention in more detail with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0072] The current micro-inverter circuit topology is mainly based on the flyback circuit topology, in which the secondary side of the transformer converts the output current into AC through a folded circuit. This circuit topology is limited by the volume of the transformer core and the switching frequency, making it difficult to increase the power, and the inverter efficiency is low. As the power of photovoltaic modules increases, the power and efficiency of micro-inverters are required to increase. Most micro-inverters in related technologies use two-stage power conversion technology, but the total efficiency of the micro-inverter during two-stage power conversion is equal to the product of the two conversion efficiencies, making it difficult for the efficiency of the micro-inverter to exceed 96%. In other words, although the power and efficiency of micro-inverters are improved by adopting a two-stage power conversion topology in related technologies, it is still difficult to meet the needs of high-power photovoltaic modules, and the device layout required for the multi-stage power conversion topology increases the cost of the micro-inverter.

[0073] In order to solve the above problems, an embodiment of the present invention provides a circuit topology of a micro-inverter, as shown in Figure 1. The circuit topology of the micro-inverter mainly includes: a resonant circuit, a winding transformer and a voltage-doubling rectifier circuit, wherein the resonant circuit is connected to the primary winding of the winding transformer, and the input end of the resonant circuit is connected to the photovoltaic module for receiving the current input by the photovoltaic module; the winding transformer generates an induced current in the secondary winding through electromagnetic induction processing based on the conduction current flowing through the primary winding; the voltage-doubling rectifier circuit includes a switch bridge arm and a capacitor bridge arm connected in parallel; the voltage-doubling rectifier circuit is connected to the secondary winding of the winding transformer, and the induced current generated by the secondary winding flows through the capacitor in the capacitor bridge arm of the voltage-doubling rectifier circuit to form an induced current loop and achieve multiple voltage boosting; wherein the output end of the voltage-doubling rectifier circuit is used to transmit a sinusoidal output current to the AC power grid.

[0074] Through the above-mentioned micro-inverter topology structure, the micro-inverter can transmit sinusoidal AC power to the AC grid through only one-stage power conversion topology, reducing the complexity of the micro-inverter circuit topology, reducing the size of the micro-inverter, reducing the cost of the micro-inverter, and effectively improving the power and efficiency of the micro-inverter, so that it can meet the needs of high-power photovoltaic modules and expand the applicable scenarios of the micro-inverter.

[0075] In some embodiments, as shown in Figure 1, when the above-mentioned resonant circuit is a full-bridge resonant circuit, it includes: a first bridge arm, a second bridge arm and an LLC circuit; wherein, the first bridge arm and the second bridge arm are connected in parallel, the first bridge arm includes a first switch tube Q1 and a second switch tube Q2 connected in series, and the second bridge arm includes a third switch tube Q3 and a fourth switch tube Q4 connected in series; the LLC circuit includes a leakage inductance Lr, an excitation inductance Lm (wherein, the excitation inductance Lm is also the primary winding of the winding transformer T1) and a resonant capacitor Cr connected in series, one end of the LLC circuit is connected to the midpoint of the first bridge arm, and the other end of the LLC circuit is connected to the midpoint of the second bridge arm.

[0076] In some embodiments, when the sinusoidal wave period corresponding to the output current is the positive half period of the sinusoidal wave, when the first switch tube and the fourth switch tube are turned on, the current input by the photovoltaic component forms a first conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit. The fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a first induced current loop in the voltage doubler rectifier circuit; wherein, the first conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the first induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in the capacitor bridge arm in sequence. When the first and fourth switching tubes are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third and second switching tubes are turned on to form a second conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit. The seventh and eighth switching tubes in the voltage doubler rectifier circuit are turned on, and the induced current forms a second induced current loop in the voltage doubler rectifier circuit; wherein, the resonant cavity current in the second conduction current loop passes through the parasitic diode of the third switching tube, the first capacitor, the parasitic diode of the second switching tube, and the LLC circuit in sequence; and the induced current in the second induced current loop passes through the third capacitor in the capacitor bridge arm, the MOS tube of the eighth switching tube, and the parasitic diode of the seventh switching tube in sequence. After the resonant cavity current is zero, the photovoltaic component inputs current to the resonant circuit through the first capacitor on the DC side bus to form a third conduction current loop, and generates an induced current in the voltage doubler rectifier circuit, and the induced current forms a third induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the third conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the third induced current loop passes through the third capacitor, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence. When the third switching tube and the second switching tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the first switching tube and the fourth switching tube are turned on to form a fourth conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit. The fifth switching tube and the sixth switching tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a fourth induced current loop in the voltage doubler rectifier circuit; wherein, the current in the fourth conduction current loop passes through the parasitic diode of the fourth switching tube, the LLC circuit, the parasitic diode of the first switching tube, and the first capacitor in sequence, and the induced current in the fourth induced current loop passes through the MOS tube of the sixth switching tube, the parasitic diode of the fifth switching tube, and the second capacitor in sequence.

[0077] In some embodiments, when the sinusoidal wave period corresponding to the output current is the negative half-cycle of the sinusoidal wave, when the first switch tube and the fourth switch tube are turned on, the current input by the photovoltaic component forms a fifth conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit. The seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a fifth induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the fifth conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the induced current in the fifth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in the capacitor bridge arm in sequence. When the first and fourth switching tubes are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus. The third and second switching tubes are turned on to form a sixth conduction current loop in the resonant circuit and generate an induced current in the voltage doubler rectifier circuit. The fifth and sixth switching tubes in the voltage doubler rectifier circuit are turned on, and the induced current forms a sixth induced current loop in the voltage doubler rectifier circuit. The resonant cavity current in the sixth conduction current loop passes through the parasitic diode of the second switching tube, the LLC circuit, the parasitic diode of the third switching tube, and the first capacitor in sequence. The induced current in the sixth induced current loop passes through the second capacitor in the capacitor bridge arm, the MOS tube of the fifth switching tube, and the parasitic diode of the sixth switching tube in sequence. After the resonant cavity current is zero, the current input by the photovoltaic component forms a seventh conduction current loop in the resonant circuit and generates an induced current in the voltage doubler rectifier circuit, and the induced current forms a seventh induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the seventh conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the seventh induced current loop passes through the second capacitor, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence. When the third switch tube and the second switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the first switch tube and the fourth switch tube in the resonant circuit are turned on to form an eighth conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit. The seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms an eighth induced current loop in the voltage doubler rectifier circuit; wherein, the current in the eighth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the eighth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in sequence.

[0078] The circuit topology of the micro-inverter provided by the embodiment of the present invention alternately controls the conduction and shutdown of multiple switching tubes in the micro-inverter during the positive half-cycle and the negative half-cycle of the sinusoidal wave corresponding to the output current, so as to form a conduction current loop in the resonant circuit and an induction current loop in the voltage-doubling rectifier circuit, respectively. In this way, sinusoidal AC power can be transmitted to the AC power grid through only one-stage power conversion, which reduces the complexity of the micro-inverter circuit topology, reduces the size of the micro-inverter, and reduces the cost of the micro-inverter caused by the device layout of the two-stage power conversion topology. It also effectively improves the power and efficiency of the micro-inverter, so that it can meet the needs of high-power photovoltaic modules and expand the applicable scenarios of the micro-inverter.

[0079] In some embodiments, as shown in Figure 2, when the above-mentioned resonant circuit is a symmetrical half-bridge resonant circuit, it includes: a first bridge arm and an LLC circuit; wherein the first bridge arm includes a first switching tube Q1 and a second switching tube Q2 connected in series; the LLC circuit includes a resonant capacitor bridge arm, and an inductance circuit composed of a leakage inductance Lr and an excitation inductance Lm connected in series, the resonant capacitor bridge arm is connected in parallel with the first bridge arm, the resonant capacitor bridge arm includes a first resonant capacitor C4 and a second resonant capacitor C5 connected in series, one end of the inductance circuit composed of the leakage inductance Lr and the excitation inductance Lm connected in series is connected to the midpoint of the first bridge arm, and the other end of the inductance circuit composed of the leakage inductance and the excitation inductance connected in series is connected to the midpoint of the resonant capacitor bridge arm.

[0080] In some embodiments, as shown in FIG3 , when the resonant circuit is an asymmetric half-bridge resonant circuit, it includes: a first bridge arm and an LLC circuit; wherein the first bridge arm includes a first switch tube Q1 and a second switch tube Q2 connected in series; the LLC circuit includes a leakage inductor Lr, an excitation inductor Lm and a resonant capacitor Cr connected in series, one end of the LLC circuit is connected to the midpoint of the first bridge arm, and the other end of the LLC circuit is connected to the negative terminal of the first bridge arm.

[0081] Among them, the LLC circuit provided by the embodiment of the present invention can realize that multiple switching tubes all operate in a soft switching state through resonance, effectively reducing the switching loss of the switching tubes and improving the power of the micro inverter.

[0082] In some embodiments, as shown in FIG1 , the switch bridge arm in the voltage doubler rectifier circuit includes an upper switch bridge arm and a lower switch bridge arm; wherein the upper switch bridge arm includes a fifth switch tube Q5 and a sixth switch tube Q6 connected in series and arranged in a mirror image, and the lower switch bridge arm includes a seventh switch tube Q7 and an eighth switch tube Q8 connected in series and arranged in a mirror image.

[0083] Among them, the upper half switch bridge arm and the lower half switch bridge arm provided by the embodiment of the present invention are both provided with two switch tubes, and the two switch tubes are connected in series and arranged in a mirror image, that is, the two switch tubes connected in series are arranged back to back, thereby realizing the bidirectional switch function of the upper half switch bridge arm and the bidirectional switch function of the lower half switch bridge arm.

[0084] In some embodiments, as shown in Figure 1, the capacitor bridge arm in the above-mentioned voltage doubler rectifier circuit includes a second capacitor C2 and a third capacitor C3 connected in series; wherein, one end of the secondary winding is connected to the midpoint of the switch bridge arm, and the other end of the secondary winding is connected to the midpoint of the capacitor bridge arm.

[0085] In some embodiments, the capacitor bridge arm in the voltage doubler rectifier circuit includes multiple capacitor sub-bridge arms connected in parallel, a first capacitor sub-bridge arm among the multiple capacitor sub-bridge arms includes a second capacitor C2 and a third capacitor C3 connected in series, one end of the secondary winding is connected to the midpoint of the switch bridge arm, and the other end of the secondary winding is connected to the midpoint of the first capacitor sub-bridge arm. As shown in Figure 4, when the capacitor bridge arm in the voltage doubler rectifier circuit includes two capacitor sub-bridge arms connected in parallel, the first capacitor sub-bridge arm includes a second capacitor C2 and a third capacitor C3 connected in series, and the other capacitor sub-bridge arm may include only a single capacitor.

[0086] The capacitor bridge arm formed by multiple capacitor sub-bridge arms connected in parallel realizes the expansion of the capacitor group in the capacitor bridge arm (the capacitor group refers to the multiple capacitors included in the capacitor bridge arm), thereby improving the boost effect of the voltage doubler rectifier circuit.

[0087] In some embodiments, at least one filter inductor Lg is provided at the output end of the voltage doubler rectifier circuit. Figures 1-3 illustrate schematic diagrams of circuit topologies in which a filter inductor Lg is provided at the output end of the voltage doubler rectifier circuit; and Figure 5 illustrates a schematic diagram of a circuit topology in which two filter inductors Lg1 and Lg2 are provided in the voltage doubler rectifier circuit.

[0088] In some embodiments, a common-mode inductor is provided at the output end of the voltage-doubling rectifier circuit. Figures 4 and 6 show schematic diagrams of circuit topologies in which a common-mode inductor is provided at the output end of the voltage-doubling rectifier circuit.

[0089] In the voltage doubler rectifier circuit in the embodiment of the present invention, the capacitor group (the capacitance value includes multiple capacitors) in the capacitor bridge arm and the inductor form an LC high-frequency filter circuit.

[0090] In some embodiments, the turns ratio between the primary winding and the secondary winding in the winding transformer provided by the embodiments of the present invention is determined by the power and number of photovoltaic modules, and is preferably 1:8 to 1:12.

[0091] The topology of the micro-inverter provided in an embodiment of the present invention includes a resonant circuit, a winding transformer, and a voltage-doubling rectifier circuit; wherein the resonant circuit is connected to the primary winding of the winding transformer, and the input end of the resonant circuit is connected to the photovoltaic module for receiving the current input by the photovoltaic module; the voltage-doubling rectifier circuit includes a switch bridge arm and a capacitor bridge arm connected in parallel; the voltage-doubling rectifier circuit is connected to the secondary winding of the winding transformer, and the induced current generated by the secondary winding flows through the capacitor in the capacitor bridge arm to form an induced current loop and achieve a multiple voltage boost; wherein the output end of the voltage-doubling rectifier circuit is used to transmit a sinusoidal output current to the AC power grid. This enables the micro-inverter to meet the requirements of transmitting sinusoidal AC power to the AC power grid through only a single-stage power conversion topology, reduces the complexity of the micro-inverter circuit topology, reduces the size of the micro-inverter, reduces the cost of the micro-inverter caused by the device layout of the two-stage power conversion topology, and effectively improves the power and efficiency of the micro-inverter, enabling it to meet the needs of high-power photovoltaic modules and expand the applicable scenarios of the micro-inverter.

[0092] In order to solve the above technical problems, an embodiment of the present invention also provides a micro inverter, including a controller and any of the above circuit topologies; wherein the controller is used to output a drive signal to control the switching state of multiple switching tubes in the circuit topology, so that the circuit topology can transmit a sinusoidal output current to the AC power grid through a first-level power conversion.

[0093] An embodiment of the present invention further provides a control method for a micro-inverter. The micro-inverter adopts any of the above-mentioned circuit topologies. As shown in FIG7 , in the process of transmitting a sinusoidal output current to an AC power grid, the control method for the micro-inverter provided by the embodiment of the present invention mainly includes:

[0094] Step S701 : detecting the maximum power value of the photovoltaic module and receiving the current input by the photovoltaic module.

[0095] Step S702: Obtain the grid voltage value in the AC grid, determine the sinusoidal wave period corresponding to the output current based on the grid voltage value and the maximum power value of the photovoltaic module, and control the on and off of multiple switching tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro inverter based on the sinusoidal wave period, so as to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, to charge the second capacitor and the third capacitor in the capacitive bridge arm of the voltage doubler rectifier circuit.

[0096] Step S703: delivering a sinusoidal output current to the AC power grid through the output end of the voltage doubler rectifier circuit.

[0097] Through the above-mentioned setting, based on the above-mentioned micro-inverter circuit topology provided by the embodiment of the present invention, the primary side adopts a resonant circuit topology, and the secondary side adopts a voltage doubler rectifier circuit. After the photovoltaic module inputs current, the conduction and shutdown of the switch tube are controlled to adjust the switching frequency to achieve circuit flipping within the sinusoidal wave cycle, and then output sinusoidal AC power to the AC power grid, thereby realizing the function of the micro-inverter to achieve AC grid connection through only one power conversion, improving the power and efficiency of the micro-inverter, reducing the cost of the micro-inverter, making the above-mentioned micro-inverter control method applicable to high-power photovoltaic modules, and expanding the applicable scenarios of the micro-inverter control method.

[0098] Among them, in step S701 provided in the embodiment of the present invention, an MTTP (Maximum Power Point Tracking) controller can be used to detect the maximum power value of the photovoltaic module, and then, when the photovoltaic module meets the maximum power value, the current input by the photovoltaic module is received, and the current input by the photovoltaic module is converted into a sinusoidal AC power through a micro-inverter through a primary conversion power topology to supply power to the AC power grid, thereby increasing the power of the micro-inverter while realizing the grid-connected function of the micro-inverter.

[0099] Among them, in step S702 provided in the embodiment of the present invention, the step of obtaining the grid voltage value in the AC power grid and determining the sinusoidal wave period corresponding to the output current based on the grid voltage value and the maximum power value of the photovoltaic component includes: obtaining the grid voltage value in the AC power grid, and determining the current value of the output current based on the grid voltage value and the maximum power value of the photovoltaic component; if the current value is greater than 0, determining that the sinusoidal wave corresponding to the output current is in the positive half-cycle of the sinusoidal wave; if the current value is less than 0, determining that the sinusoidal wave corresponding to the output current is in the negative half-cycle of the sinusoidal wave; wherein the sinusoidal wave frequency of the output current is consistent with the sinusoidal wave frequency of the AC power in the AC power grid.

[0100] Through the above settings, combined with the current demand of the AC power grid and the maximum power value of the photovoltaic module, the sine wave period corresponding to the output current of the microinverter is determined. This helps to control the conduction and shutdown of multiple switching tubes in the microinverter based on the sine wave period. That is, by controlling the switching frequency of the switching tube, the current circuit within the sine wave period is flipped to output sinusoidal AC power that meets the requirements of the AC power grid.

[0101] Among them, in step S702 provided in an embodiment of the present invention, the above-mentioned step of controlling the conduction and shutdown of multiple switching tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter according to the sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, includes: determining the positive half-cycle and negative half-cycle of the sine wave corresponding to the sine wave cycle of the output current, and alternately controlling the conduction and shutdown of multiple switching tubes in the micro-inverter according to the positive half-cycle and negative half-cycle of the sine wave to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively.

[0102] According to a specific implementation of an embodiment of the present invention, when the sinusoidal wave cycle corresponding to the output current is in the positive half-cycle of the sinusoidal wave, the conduction and shutdown of multiple switching tubes in the micro-inverter are controlled to form a positive half-cycle conduction current loop and a positive half-cycle inductive current loop in the resonant circuit and the voltage doubler rectifier circuit, respectively; when the sinusoidal wave cycle of the output current is in the negative half-cycle of the sinusoidal wave, the conduction and shutdown of multiple switching tubes in the micro-inverter are controlled to form a negative half-cycle conduction current loop and a negative half-cycle inductive current loop in the resonant circuit and the voltage doubler rectifier circuit, respectively. Among them, when the resonant circuit is a full-bridge resonant circuit, the positive half-cycle conduction current loop includes the above-mentioned first conduction current loop, the second conduction current loop, the third conduction current loop and the fourth conduction current loop, and accordingly, the positive half-cycle induction current loop includes the above-mentioned first induction current loop, the second induction current loop, the third induction current loop and the fourth induction current loop; the negative half-cycle conduction current loop includes the above-mentioned fifth conduction current loop, the sixth conduction current loop, the seventh induction current loop and the eighth induction current loop, and accordingly, the negative half-cycle induction current loop includes the above-mentioned fifth induction current loop, the sixth induction current loop, the seventh induction current loop and the eighth induction current loop. Through the above-mentioned setting, combined with the positive half-cycle and the negative half-cycle of the sine wave corresponding to the output current, the conduction and shutdown of multiple switching tubes in the micro-inverter are alternately controlled, so that the positive half-cycle induction current loop and the negative half-cycle induction current loop achieve the current circuit reversal of the output current, thereby achieving the current circuit reversal of the output current within a sine wave cycle, and achieving the transmission of sinusoidal AC power to the AC grid through only one-stage power conversion, thereby improving the power and efficiency of the micro-inverter.

[0103] In some embodiments, the step of controlling the on and off of the multiple switches in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively, includes: controlling the on and off of the multiple switches in the resonant circuit, so that the current input by the photovoltaic module and the resonant cavity current in the resonant circuit flow through the conducted switches to form a flipped conduction current loop, and generating an induction current in the voltage doubler rectifier circuit, and controlling the on and off of the multiple switches in the voltage doubler rectifier circuit so that the induction current flows through the target capacitor of the voltage doubler rectifier circuit to form a corresponding induction current loop. At the same time, when the current source in the conduction current loop and the switch in the resonant circuit through which the conduction current flows are the same, in the positive half cycle of the sine wave and the negative half cycle of the sine wave, the target capacitor through which the induction current flows in the induction current loop corresponding to the conduction current loop is different; wherein the target capacitor includes the second capacitor and the third capacitor in the capacitor bridge arm of the voltage doubler rectifier circuit.

[0104] Among them, the current source in the above-mentioned conduction current loop includes the current input by the photovoltaic module and the resonant cavity current of the resonant circuit. In the positive half-cycle and the negative half-cycle of the sine wave, when the current source in the conduction current loop and the switch tube in the resonant circuit through which the conduction current flows are the same, the target capacitor (the target capacitor refers to the capacitor included in the capacitor bridge arm in the voltage doubler rectifier circuit, which constitutes a high-frequency filter circuit with the filter inductor for filtering the output current) through which the induced current in the induced current corresponding to the conduction current loop flows is the second capacitor and the third capacitor, respectively, that is, corresponding to different cycles of the sine wave (here refers to the positive half-cycle and the negative half-cycle), by controlling the conduction and closing of multiple switch tubes, the output current in the voltage doubler rectifier circuit is reversed, thereby realizing the transmission of sinusoidal AC power to the AC power grid through only one-stage power conversion.

[0105] In some embodiments, if the sine wave period is the positive half cycle of the sine wave, the switching frequencies of multiple switching tubes in the circuit topology are adjusted according to the frequency of the sine wave; when the first switching tube and the fourth switching tube in the resonant circuit are turned on, the current input by the photovoltaic component forms a first conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, controlling the conduction of the fifth switching tube and the sixth switching tube in the voltage doubler rectifier circuit, and the induced current flows through the second capacitor in the capacitor bridge arm in the voltage doubler rectifier circuit to form a first induced current loop; wherein, the current input by the photovoltaic component in the first conduction current loop passes through the MOS tube of the first switching tube, the LLC circuit, the MOS tube of the fourth switching tube, and the first capacitor on the DC side bus in sequence; the induced current in the first induced current loop passes through the MOS tube of the sixth switching tube, the parasitic diode of the fifth switching tube, and the second capacitor in sequence. When the first and fourth switching tubes in the resonant circuit are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controlling the third and second switching tubes in the resonant circuit to be turned on to form a second conduction current loop, and generating an induced current in the voltage doubler rectifier circuit. The seventh and eighth switching tubes in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the third capacitor in the capacitor bridge arm to form a second induced current loop; wherein, the resonant cavity current in the second conduction current loop passes through the parasitic diode of the third switching tube, the first capacitor, the parasitic diode of the second switching tube, and the LLC circuit in sequence; and the induced current in the second induced current loop passes through the third capacitor, the MOS tube of the eighth switching tube, and the parasitic diode of the seventh switching tube in sequence. When the resonant cavity current is zero, the photovoltaic component inputs current into the resonant circuit through the first capacitor on the DC side bus to form a third conduction current loop, and generates an induced current in the voltage doubler rectifier circuit. The induced current flows through the third capacitor in the capacitor bridge arm to form a third induced current loop; wherein, the current input by the photovoltaic component in the third conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the third induced current loop passes through the third capacitor, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence. When the third and second switching tubes in the resonant circuit are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controlling the first and fourth switching tubes to be turned on to form a fourth conduction current loop, and generating an induced current in the voltage doubler rectifier circuit. The fifth and sixth switching tubes are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm to form a fourth induced current loop; wherein, the current in the fourth conduction current loop passes through the parasitic diode of the fourth switching tube, the LLC circuit, the parasitic diode of the first switching tube, and the first capacitor in sequence, and the induced current in the fourth induced current loop passes through the MOS tube of the sixth switching tube, the parasitic diode of the fifth switching tube, and the second capacitor in sequence.

[0106] Figures 8a, 8b, 8c, and 8d illustrate current flow diagrams of a conduction current loop and an induction current loop in a circuit topology of a micro-inverter during a positive half-cycle of a sinusoidal wave. In some embodiments, as shown in Figure 8a, when the first switch Q1 and the fourth switch Q4 in the resonant circuit are turned on, the current input from the photovoltaic module (PV module) flows through the MOS transistor of the first switch Q1, the leakage inductor Lr, the primary winding of the winding transformer T1, the resonant capacitor Cr, and the MOS transistor of the fourth switch Q4 to form a first conduction current loop. Simultaneously, the induced current generated by the secondary side of the winding transformer T1 flows out from the same-name terminal of the secondary side of the winding transformer T1, passes through the MOS transistor of the sixth switch Q6, the parasitic diode of the fifth switch Q5, and the second capacitor C2, and then flows back to the opposite-name terminal of the secondary winding of the winding transformer T1 to form a first induction current loop. As shown in FIG8b , when the first switch Q1 and the fourth switch Q4 in the resonant circuit are turned off, the current in the resonant cavity drives the third switch Q3 and the second switch Q2 to turn on. The conduction current passes through the parasitic diode of the third switch Q3, the DC bus capacitor C1, the parasitic diode of the second switch Q2, Lr, the primary winding of the winding transformer T1, and Cr to form a second conduction current loop. At the same time, the induced current flows out from the opposite-name end of the secondary winding of the winding transformer T1, passes through the third capacitor C3, the MOS transistor of the eighth switch Q8, and the parasitic diode of the seventh switch Q7, and returns to the same-name end of the secondary winding of the winding transformer T1, forming a second induced current loop. As shown in FIG8c , after the resonant cavity current drops to zero, the current input by the photovoltaic module passes through the MOS transistor of the third switching transistor Q3, Cr, the primary winding of the winding transformer T1, Lr, the MOS transistor of the second switching transistor Q2, and the first capacitor C1 to form a third conduction current loop. During this process, the induced current flows out from the opposite-name terminal of the secondary winding of the winding transformer T1, passes through the third capacitor C3, the MOS transistor of the eighth switching transistor Q8, and the parasitic diode of the seventh switching transistor Q7, and returns to the same-name terminal of the secondary winding of the winding transformer T1, forming a third induced current loop. As shown in FIG8 d , when the second switch tube Q2 and the third switch tube Q3 in the resonant circuit are turned off, the current in the resonant cavity drives the first switch tube Q1 and the fourth switch tube Q4 to turn on. The resonant cavity current passes through the parasitic diode, Cr, Lm, Lr of the fourth switch tube Q4, and the parasitic diode of the first switch tube Q1, and flows back to the first capacitor C1 to form a fourth conduction current loop. At the same time, the induced current flows out from the same-name terminal of the secondary side of the winding transformer T1, passes through the MOS transistor of the sixth switch tube Q6, the parasitic diode of the fifth switch tube Q5, and the second capacitor C2, and flows back to the opposite-name terminal of the secondary winding of the winding transformer T1, forming a fourth induced current loop.

[0107] In some embodiments, if the sine wave period is the negative half-cycle of the sine wave, the steps of controlling the switching frequency of multiple switching tubes in the circuit topology according to the frequency of the sine wave are as follows: when the first switching tube and the fourth switching tube in the resonant circuit are turned on, the current input by the photovoltaic component forms a fifth conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, controlling the seventh switching tube and the eighth switching tube in the voltage doubler rectifier circuit to be turned on, and the induced current flows through the third capacitor in the capacitor bridge arm in the voltage doubler rectifier circuit to form a fifth induced current loop; wherein, the current input by the photovoltaic component in the fifth conduction current loop passes through the MOS tube of the first switching tube, the LLC circuit, the MOS tube of the fourth switching tube, and the first capacitor on the DC side bus in sequence; the induced current in the fifth induced current loop passes through the MOS tube of the seventh switching tube, the parasitic diode of the eighth switching tube, and the third capacitor in sequence. When the first and fourth switching tubes in the resonant circuit are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controlling the third and second switching tubes in the resonant circuit to be turned on to form a sixth conduction current loop, and generating an induced current in the voltage-doubling rectifier circuit. The fifth and sixth switching tubes in the voltage-doubling rectifier circuit are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm to form a sixth induced current loop; wherein, the resonant cavity current in the sixth conduction current loop passes through the parasitic diode of the second switching tube, the LLC circuit, the parasitic diode of the third switching tube, and the first capacitor in sequence; and the induced current in the sixth induced current loop passes through the second capacitor, the MOS tube of the fifth switching tube, and the parasitic diode of the sixth switching tube in sequence. When the resonant cavity current is zero, the current input by the photovoltaic module forms a seventh conduction current loop in the resonant circuit and generates an induced current in the voltage-doubling rectifier circuit. The induced current flows through the second capacitor of the capacitor bridge arm to form a seventh induced current loop. In the seventh conduction current loop, the current input by the photovoltaic module passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence. The induced current in the seventh induced current loop passes through the second capacitor, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence. When the third and second switching tubes in the resonant circuit are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controlling the first and fourth switching tubes to be turned on to form an eighth conduction current loop, generating an induced current in the voltage doubler rectifier circuit, controlling the seventh and eighth switching tubes to be turned on, and the induced current flows through the third capacitor of the capacitor bridge arm to form an eighth induced current loop; wherein, the current in the eighth conduction current loop passes through the parasitic diode of the fourth switching tube, the LLC circuit, the parasitic diode of the first switching tube, and the first capacitor in sequence, and the induced current in the eighth induced current loop passes through the MOS tube of the seventh switching tube, the parasitic diode of the eighth switching tube, and the third capacitor in sequence.

[0108] Figures 8e, 8f, 8g, and 8h illustrate current flow diagrams of the conduction current loop and the induction current loop in the micro-inverter circuit topology during the negative and positive half-cycles of a sine wave. In some embodiments, as shown in Figure 8e, when the first switch tube Q1 and the fourth switch tube Q4 in the resonant circuit are turned on, the current input by the photovoltaic module flows through the MOS transistor of the first switch tube Q1, the leakage inductor Lr, the primary winding of the winding transformer T1, the resonant capacitor Cr, and the transistor of the fourth switch tube Q4, and returns to the first capacitor C1 on the DC bus to form a fifth conduction current loop; at the same time, the induced current generated by the secondary side of the winding transformer T1 flows out from the same-name terminal of the secondary side of the winding transformer T1, passes through the MOS transistor of the seventh switch tube Q7, the parasitic diode of the eighth switch tube Q8, and the third capacitor C3, and then flows back to the opposite-name terminal of the secondary winding of the winding transformer T1 to form a fifth induction current loop. As shown in FIG8f , when the first switch Q1 and the fourth switch Q4 in the resonant circuit are turned off, the current in the resonant cavity drives the third switch Q3 and the second switch Q2 to turn on. The conduction current flows through the parasitic diode Cr of the second switch Q2, the primary winding Lr of the winding transformer T1, and the parasitic diode of the third switch Q3 to form a sixth conduction current loop. At the same time, the induced current flows out from the opposite-name terminal of the secondary winding of the winding transformer T1, passes through the second capacitor C2, the MOS transistor of the fifth switch Q5, and the parasitic diode of the sixth switch Q6, and returns to the same-name terminal of the secondary winding of the winding transformer T1, forming a sixth induced current loop. As shown in FIG8g , after the resonant cavity current drops to zero, the current input by the photovoltaic module flows through the MOS transistor of the third switching transistor Q3, Cr, the primary winding of the winding transformer T1, Lr, the MOS transistor of the second switching transistor Q2, and returns to the first capacitor C1 to form a seventh conduction current loop. During this process, the induced current flows out from the opposite-name terminal of the secondary winding of the winding transformer T1, passes through the second capacitor C2, the MOS transistor of the fifth switching transistor Q5, and the parasitic diode of the sixth switching transistor Q6, and returns to the same-name terminal of the secondary winding of the winding transformer T1, forming a seventh induced current loop. As shown in FIG8h , after the second switch tube Q2 and the third switch tube Q3 in the resonant circuit are turned off, the current in the resonant cavity drives the first switch tube Q1 and the fourth switch tube Q4 to turn on. The resonant cavity current passes through the parasitic diode, Cr, Lm, Lr of the fourth switch tube Q4, and the parasitic diode of the first switch tube Q1, and flows back to the first capacitor C1 to form an eighth conduction current loop. At the same time, the induced current flows out from the same-name terminal of the secondary side of the winding transformer T1, passes through the MOS transistor of the seventh switch tube Q7, the parasitic diode of the eighth switch tube Q8, and the third capacitor C3, and flows back to the opposite-name terminal of the secondary winding of the winding transformer T1, forming an eighth induced current loop.

[0109] Through the above setting, after the photovoltaic module inputs current, the switching frequency is adjusted by controlling the on and off of the switch tube to achieve current circuit reversal within the sine wave cycle, and then output sinusoidal AC power to the AC power grid. This realizes the function of the micro-inverter to achieve AC grid connection through only one power conversion, improves the power and efficiency of the micro-inverter, and reduces the cost of the micro-inverter.

[0110] In some embodiments, the operating state of the plurality of switch tubes is a soft switching state.

[0111] In the micro-inverter with a one-stage power conversion topology provided by the embodiment of the present invention, multiple switching tubes can operate in a soft switching state, thereby reducing switching losses and thereby improving the power generation capacity of the micro-inverter.

[0112] The control method for the micro-inverter provided in an embodiment of the present invention detects the maximum power value of a photovoltaic module and receives the current input by the photovoltaic module; obtains the grid voltage value in the AC power grid, determines the sinusoidal wave period corresponding to the output current based on the grid voltage value and the maximum power value of the photovoltaic module, and controls the conduction and shutdown of multiple switching tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter according to the sinusoidal wave period, so as to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit, respectively. The technical means of transmitting a sinusoidal output current to the AC power grid through the output end of the voltage doubler rectifier circuit overcomes the problems of low efficiency, power and high cost of micro-inverters caused by the use of a two-stage power conversion control strategy in related technologies, and realizes the function of outputting sinusoidal AC power and connecting to the grid of the micro-inverter through only one-stage power conversion, effectively improving the power and efficiency of the micro-inverter, expanding the applicable scenarios of the micro-inverter, and reducing the cost of the micro-inverter by reducing the device layout required for the multi-stage power conversion topology.

[0113] An embodiment of the present invention further provides a micro-inverter, comprising: at least one processor; and a memory communicatively connected to the at least one processor. The memory stores a computer program executable by the at least one processor, and when executed by the at least one processor, the computer program causes an electronic device to perform the method of an embodiment of the present invention.

[0114] An embodiment of the present invention further provides a non-transitory machine-readable medium storing a computer program, wherein the computer program, when executed by a processor of a computer, is used to cause the computer to perform the method of the embodiment of the present invention.

[0115] An embodiment of the present invention further provides a computer program product, including a computer program, wherein when the computer program is executed by a processor of a computer, it is used to enable the computer to perform the method of the embodiment of the present invention.

[0116] With reference to Figure 9, the structural block diagram of the electronic device that can be used as the server or client of an embodiment of the present invention will now be described, which is an example of a hardware device that can be applied to various aspects of the present invention. The electronic device is intended to represent various forms of digital electronic computer equipment, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0117] As shown in Figure 9, the electronic device includes a computing unit 901, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 902 or a computer program loaded from a storage unit 908 into a random access memory (RAM) 903. In the RAM 903, various programs and data required for the operation of the electronic device can also be stored. The computing unit 901, ROM 902, and RAM 903 are connected to each other via a bus 904. An input / output (I / O) interface 905 is also connected to the bus 904.

[0118] Multiple components within the electronic device are connected to the I / O interface 905, including an input unit 906, an output unit 907, a storage unit 908, and a communication unit 909. The input unit 906 can be any type of device capable of inputting information into the electronic device. The input unit 906 can receive input numeric or character information and generate key signal inputs related to user settings and / or function control of the electronic device. The output unit 907 can be any type of device capable of presenting information and may include, but is not limited to, a display, a speaker, a video / audio output terminal, a vibrator, and / or a printer. The storage unit 908 may include, but is not limited to, a magnetic disk or an optical disk. The communication unit 909 allows the electronic device to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks, and may include, but is not limited to, a modem, a network card, an infrared communication device, a wireless communication transceiver, and / or a chipset, such as a Bluetooth device, a WiFi device, a WiMax device, a cellular communication device, and / or the like.

[0119] The computing unit 901 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 901 include, but are not limited to, a CPU, a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units that run machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 901 performs the various methods and processes described above. For example, in some embodiments, the method embodiments of the present invention may be implemented as a computer program, which is tangibly contained in a machine-readable medium, such as a storage unit 908. In some embodiments, part or all of the computer program may be loaded and / or installed on an electronic device via the ROM 902 and / or the communication unit 909. In some embodiments, the computing unit 901 may be configured to perform the above-described method in any other appropriate manner (e.g., by means of firmware).

[0120] The computer programs for implementing the methods of the embodiments of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer programs are executed by the processor or controller, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer programs may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0121] In the context of an embodiment of the present invention, a machine-readable medium can be a tangible medium that can contain or store a program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable signal medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, device or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0122] It should be noted that the term "including" and its variations used in the embodiments of the present invention are open-ended, i.e., "including but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; and the term "some embodiments" means "at least some embodiments." The modifications of "one" and "a plurality of" mentioned in the embodiments of the present invention are illustrative and non-restrictive. Those skilled in the art should understand that, unless the context clearly indicates otherwise, they should be understood as "one or more."

[0123] The various steps described in the method implementation scheme provided in the embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method implementation scheme may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0124] The term "embodiment" in this specification refers to specific features, structures, or characteristics described in conjunction with the embodiment that can be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. The various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments are referenced to each other. In particular, for the embodiments of the device, equipment, and system, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts are referred to the partial description of the method embodiment.

[0125] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A circuit topology of a micro inverter, characterized in that: It includes a resonant circuit, a winding transformer and a voltage doubler rectifier circuit, wherein: The resonant circuit is connected to the primary winding of the winding transformer, and the input end of the resonant circuit is connected to the photovoltaic component to receive the current input by the photovoltaic component; The voltage-doubling rectifier circuit comprises a switch bridge arm and a capacitor bridge arm connected in parallel; the voltage-doubling rectifier circuit is connected to the secondary winding of the winding transformer, and the induced current generated by the secondary winding flows through the capacitor in the capacitor bridge arm to form an induced current loop and realize multiple voltage boosting; wherein the output end of the voltage-doubling rectifier circuit is used to transmit a sinusoidal output current to an AC power grid.

2. The circuit topology according to claim 1, characterized in that: When the resonant circuit is a full-bridge resonant circuit, it includes: a first bridge arm, a second bridge arm and an LLC circuit; wherein the first bridge arm and the second bridge arm are connected in parallel, the first bridge arm includes a first switch tube and a second switch tube connected in series, and the second bridge arm includes a third switch tube and a fourth switch tube connected in series; the LLC circuit includes a leakage inductance, an excitation inductance and a resonant capacitor connected in series, one end of the LLC circuit is connected to the midpoint of the first bridge arm, and the other end of the LLC circuit is connected to the midpoint of the second bridge arm.

3. The circuit topology according to claim 2, characterized in that: When the sinusoidal wave period corresponding to the output current is the positive half period of the sinusoidal wave, when the first switch tube and the fourth switch tube are turned on, the current input by the photovoltaic component forms a first conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, the fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a first induced current loop in the voltage doubler rectifier circuit; wherein, the first conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the first induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in the capacitor bridge arm in sequence.

4. The circuit topology according to claim 3, characterized in that: When the first switch tube and the fourth switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third switch tube and the second switch tube are turned on to form a second conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit, the seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a second induced current loop in the voltage doubler rectifier circuit; wherein the resonant cavity current in the second conduction current loop passes through the parasitic diode of the third switch tube, the first capacitor, the parasitic diode of the second switch tube, and the LLC circuit in sequence; the induced current in the second induced current loop passes through the third capacitor in the capacitor bridge arm, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence.

5. The circuit topology according to claim 4, characterized in that: After the resonant cavity current is zero, the photovoltaic component inputs current to the resonant circuit through the first capacitor on the DC side bus to form a third conduction current loop, and generates an induced current in the voltage doubler rectifier circuit, and the induced current forms a third induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the third conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the third induced current loop passes through the third capacitor, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence.

6. The circuit topology according to claim 5, characterized in that: When the third switch tube and the second switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the first switch tube and the fourth switch tube are turned on to form a fourth conduction current loop in the resonant circuit, and an induced current is generated in the voltage doubler rectifier circuit, the fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a fourth induced current loop in the voltage doubler rectifier circuit; wherein the current in the fourth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the fourth induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in sequence.

7. The circuit topology according to claim 2, characterized in that: When the sinusoidal wave period corresponding to the output current is the negative half period of the sinusoidal wave, when the first switch tube and the fourth switch tube are turned on, the current input by the photovoltaic component forms a fifth conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit. The seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a fifth induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the fifth conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the induced current in the fifth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in the capacitor bridge arm in sequence.

8. The circuit topology according to claim 7, characterized in that: When the first switch tube and the fourth switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third switch tube and the second switch tube are turned on to form a sixth conduction current loop in the resonant circuit, and generate an induced current in the voltage doubler rectifier circuit, the fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms a sixth induced current loop in the voltage doubler rectifier circuit; wherein, the resonant cavity current in the sixth conduction current loop passes through the parasitic diode of the second switch tube, the LLC circuit, the parasitic diode of the third switch tube, and the first capacitor in sequence; the induced current in the sixth induced current loop passes through the second capacitor in the capacitor bridge arm, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence.

9. The circuit topology according to claim 8, characterized in that: After the resonant cavity current is zero, the current input by the photovoltaic component forms a seventh conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, and the induced current forms a seventh induced current loop in the voltage doubler rectifier circuit; wherein, the current input by the photovoltaic component in the seventh conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the seventh induced current loop passes through the second capacitor, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence.

10. The circuit topology according to claim 9, characterized in that: When the third switch tube and the second switch tube are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the first switch tube and the fourth switch tube in the resonant circuit are turned on to form an eighth conduction current loop in the resonant circuit, and an induced current is generated in the voltage doubler rectifier circuit, the seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are turned on, and the induced current forms an eighth induced current loop in the voltage doubler rectifier circuit; wherein the current in the eighth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the eighth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in sequence.

11. The circuit topology according to claim 1, characterized in that: When the resonant circuit is a symmetrical half-bridge resonant circuit, it includes: a first bridge arm and an LLC circuit; wherein the first bridge arm includes a first switching tube and a second switching tube connected in series; the LLC circuit includes a resonant capacitor bridge arm, and an inductance circuit composed of a leakage inductance and an excitation inductance connected in series, the resonant capacitor bridge arm is connected in parallel with the first bridge arm, the resonant capacitor bridge arm includes a first resonant capacitor and a second resonant capacitor connected in series, one end of the inductance circuit composed of a leakage inductance and an excitation inductance connected in series is connected to the midpoint of the first bridge arm, and the other end of the inductance circuit composed of a leakage inductance and an excitation inductance connected in series is connected to the midpoint of the resonant capacitor bridge arm.

12. The circuit topology according to claim 1, characterized in that: When the resonant circuit is an asymmetric half-bridge resonant circuit, it includes: a first bridge arm and an LLC circuit; wherein the first bridge arm includes a first switch tube and a second switch tube connected in series; the LLC circuit includes a leakage inductance, an excitation inductance and a resonant capacitor connected in series, one end of the LLC circuit is connected to the midpoint of the first bridge arm, and the other end of the LLC circuit is connected to the negative terminal of the first bridge arm.

13. The circuit topology according to claim 1, characterized in that: The switch bridge arm includes an upper switch bridge arm and a lower switch bridge arm; wherein the upper switch bridge arm includes a fifth switch tube and a sixth switch tube connected in series and arranged in a mirror image, and the lower switch bridge arm includes a seventh switch tube and an eighth switch tube connected in series and arranged in a mirror image.

14. The circuit topology according to claim 1, characterized in that: The capacitor bridge arm includes a second capacitor and a third capacitor connected in series; one end of the secondary winding is connected to the midpoint of the switch bridge arm, and the other end of the secondary winding is connected to the midpoint of the capacitor bridge arm.

15. The circuit topology according to claim 1, characterized in that: The capacitor bridge arm includes multiple capacitor sub-bridge arms connected in parallel, and the first capacitor sub-bridge arm among the multiple capacitor sub-bridge arms includes a second capacitor and a third capacitor connected in series, one end of the secondary winding is connected to the midpoint of the switch bridge arm, and the other end of the secondary winding is connected to the midpoint of the first capacitor sub-bridge arm.

16. The circuit topology according to claim 1, characterized in that: At least one filter inductor is provided at the output end of the voltage doubler rectifier circuit.

17. The circuit topology according to claim 1, characterized in that: The output end of the voltage doubler rectifier circuit is provided with a common mode inductor.

18. A micro inverter, characterized in that: A controller and a circuit topology according to any one of claims 1 to 17; The controller is used to output a driving signal to control the switching states of multiple switch tubes in the circuit topology. state, so that the circuit topology transmits a sinusoidal output current to the AC power grid via a primary power conversion.

19. A control method for a micro inverter, characterized in that: The micro inverter adopts the circuit topology described in any one of claims 1 to 17; the control method comprises: Detecting the maximum power value of the photovoltaic module and receiving the current input by the photovoltaic module; Obtaining a grid voltage value in the AC grid, determining a sine wave period corresponding to an output current according to the grid voltage value and a maximum power value of the photovoltaic module, and controlling the on and off of a plurality of switch tubes in a resonant circuit and a voltage doubler rectifier circuit in the micro-inverter according to the sine wave period, so as to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively; A sinusoidal output current is transmitted to the AC power grid through the output end of the voltage doubler rectifier circuit.

20. The control method according to claim 19, characterized in that: The step of controlling the on and off of a plurality of switch tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro inverter according to the sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively comprises: Determine the positive half cycle of the sine wave and the negative half cycle of the sine wave corresponding to the sine wave period of the output current, and alternately control the on and off of multiple switching tubes in the micro inverter according to the positive half cycle of the sine wave and the negative half cycle of the sine wave to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively.

21. The control method according to claim 19, characterized in that: The step of obtaining the grid voltage value in the AC grid and determining the sine wave period corresponding to the output current according to the grid voltage value and the maximum power value of the photovoltaic module includes: Acquiring a grid voltage value in the AC grid, and determining a current value of the output current according to the grid voltage value and a maximum power value of the photovoltaic module; If the current value is greater than 0, it is determined that the sine wave corresponding to the output current is in the positive half-cycle of the sine wave; if the current value is less than 0, it is determined that the sine wave corresponding to the output current is in the negative half-cycle of the sine wave; wherein the sine wave frequency of the output current is consistent with the sine wave frequency of the grid AC in the AC power grid.

22. The control method according to claim 20, characterized in that: The step of controlling the on and off of a plurality of switch tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro-inverter to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively comprises: Control the on and off of multiple switching tubes in the resonant circuit, so that the current input by the photovoltaic component and the resonant cavity current in the resonant circuit flow through the turned-on switching tubes in turn to form a flipped current loop, and generate an induced current in the voltage doubler rectifier circuit, and control the on and off of multiple switching tubes in the voltage doubler rectifier circuit so that the induced current flows through the target capacitor of the voltage doubler rectifier circuit to form a corresponding induced current loop.

23. The control method according to claim 22, characterized in that: When the current source in the conduction current loop and the switch tube in the resonant circuit through which the conduction current flows are the same, in the positive half cycle of the sine wave and the negative half cycle of the sine wave, the target capacitance through which the induced current flows in the induced current loop corresponding to the conduction current loop is different; wherein the target capacitance includes the second capacitance and the third capacitance in the capacitance bridge arm of the voltage doubler rectifier circuit.

24. The control method according to claim 20, characterized in that: The step of controlling the on and off of a plurality of switch tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro inverter according to the sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively comprises: If the sine wave period is a positive half period of a sine wave, the switching frequencies of the multiple switch tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the first switch tube and the fourth switch tube in the resonant circuit are controlled to be turned on, the current input by the photovoltaic component forms a first conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit. The fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm of the voltage doubler rectifier circuit to form a first induced current loop; wherein, the current input by the photovoltaic component in the first conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the induced current in the first induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in sequence.

25. The control method according to claim 24, characterized in that: If the sine wave period is a positive half period of a sine wave, the switching frequencies of the multiple switch tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the first switch tube and the fourth switch tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third switch tube and the second switch tube in the resonant circuit are controlled to be turned on to form a second conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit. The seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the third capacitor in the capacitor bridge arm to form a second induced current loop; wherein the resonant cavity current in the second conduction current loop passes through the parasitic diode of the third switch tube, the first capacitor, the parasitic diode of the second switch tube, and the LLC circuit in sequence; the induced current in the second induced current loop passes through the third capacitor, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence.

26. The control method according to claim 25, characterized in that: If the sine wave period is a positive half period of a sine wave, the switching frequencies of the multiple switching tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the current in the resonant cavity is zero, the photovoltaic component inputs current to the resonant circuit through the first capacitor on the DC side bus to form a third conduction current loop, and generates an induced current in the voltage doubler rectifier circuit. The induced current flows through the third capacitor in the capacitor bridge arm to form a third induced current loop; wherein the current input by the photovoltaic component in the third conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the third induced current loop passes through the third capacitor, the MOS tube of the eighth switch tube, and the parasitic diode of the seventh switch tube in sequence.

27. The control method according to claim 26, characterized in that: If the sine wave period is a positive half period of a sine wave, the switching frequencies of the multiple switch tubes in the circuit topology are adjusted according to the frequency of the sine wave. When the third switch tube and the second switch tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit feeds power to the first capacitor on the DC side bus, the first switch tube and the fourth switch tube are controlled to be turned on to form a fourth conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit. The fifth switch tube and the sixth switch tube are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm to form a fourth induced current loop; wherein the current in the fourth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the fourth induced current loop passes through the MOS tube of the sixth switch tube, the parasitic diode of the fifth switch tube, and the second capacitor in sequence.

28. The control method according to claim 20, characterized in that: The step of controlling the on and off of a plurality of switch tubes in the resonant circuit and the voltage doubler rectifier circuit in the micro inverter according to the sine wave cycle to form a conduction current loop in the resonant circuit and an induction current loop in the voltage doubler rectifier circuit respectively comprises: If the sine wave period is the negative half period of the sine wave, the switching frequencies of multiple switch tubes in the circuit topology are controlled according to the frequency of the sine wave; when the first switch tube and the fourth switch tube in the resonant circuit are controlled to be turned on, the current input by the photovoltaic component forms a fifth conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, and the seventh switch tube and the eighth switch tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the third capacitor in the capacitor bridge arm of the voltage doubler rectifier circuit to form a fifth induced current loop; wherein, the current input by the photovoltaic component in the fifth conduction current loop passes through the MOS tube of the first switch tube, the LLC circuit, the MOS tube of the fourth switch tube, and the first capacitor on the DC side bus in sequence; the induced current in the fifth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in sequence.

29. The control method according to claim 28, characterized in that: If the sine wave period is the negative half period of the sine wave, the switching frequencies of the multiple switch tubes in the circuit topology are controlled according to the frequency of the sine wave; when the first switch tube and the fourth switch tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, the third switch tube and the second switch tube in the resonant circuit are controlled to be turned on to form a sixth conduction current loop, and an induced current is generated in the voltage doubler rectifier circuit, the fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit are controlled to be turned on, and the induced current flows through the second capacitor in the capacitor bridge arm to form a sixth induced current loop; wherein, the resonant cavity current in the sixth conduction current loop passes through the parasitic diode of the second switch tube, the LLC circuit, the parasitic diode of the third switch tube, and the first capacitor in sequence; the induced current in the sixth induced current loop passes through the second capacitor, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence.

30. The control method according to claim 29, characterized in that: If the sine wave period is the negative half period of the sine wave, the switching frequencies of the multiple switching tubes in the circuit topology are controlled according to the frequency of the sine wave; when the resonant cavity current is zero, the current input by the photovoltaic component forms a seventh conduction current loop in the resonant circuit, and generates an induced current in the voltage doubler rectifier circuit, and the induced current flows through the second capacitor of the capacitor bridge arm to form a seventh induced current loop; wherein, the current input by the photovoltaic component in the seventh conduction current loop passes through the MOS tube of the third switch tube, the LLC circuit, the MOS tube of the second switch tube, and the first capacitor in sequence, and the induced current in the seventh induced current loop passes through the second capacitor, the MOS tube of the fifth switch tube, and the parasitic diode of the sixth switch tube in sequence.

31. The control method according to claim 30, characterized in that: If the sine wave period is the negative half period of the sine wave, the switching frequencies of the multiple switch tubes in the circuit topology are controlled according to the frequency of the sine wave; when the third switch tube and the second switch tube in the resonant circuit are controlled to be turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controls the first switch tube and the fourth switch tube to be turned on to form an eighth conduction current loop, and generates an induced current in the voltage doubler rectifier circuit, controls the seventh switch tube and the eighth switch tube to be turned on, and the induced current flows through the third capacitor of the capacitor bridge arm to form an eighth induced current loop; wherein the current in the eighth conduction current loop passes through the parasitic diode of the fourth switch tube, the LLC circuit, the parasitic diode of the first switch tube, and the first capacitor in sequence, and the induced current in the eighth induced current loop passes through the MOS tube of the seventh switch tube, the parasitic diode of the eighth switch tube, and the third capacitor in sequence.

32. The control method according to claim 19, characterized in that: The working state of the plurality of switch tubes is a soft switching state.

33. A micro inverter comprising: A processor, and a memory storing a program, wherein the program comprises instructions, which, when executed by the processor, cause the processor to perform the method according to any one of claims 19-32.

34. A non-transitory machine-readable medium storing computer instructions, characterized in that: The computer instructions are used to cause the computer to execute the method according to any one of claims 19-32.

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