Circuit topology and control method of micro inverter

Abstract

The invention relates to a circuit topology of a micro inverter and a control method, and relates to the technical field of micro inverters. One specific embodiment of the method comprises the following steps: detecting the maximum power value of the photovoltaic module, and receiving the current input by the photovoltaic module; obtaining a power grid voltage value in the alternating current power grid, determining a sine wave period corresponding to the output current according to the power grid voltage value and the maximum power value of the photovoltaic module, and controlling a resonance circuit in the micro inverter and a plurality of switching tubes in a voltage doubling rectifying circuit to be switched on and switched off according to the sine wave period. A conduction current loop is formed in the resonance circuit, and an induction current loop is formed in the voltage doubling rectifying circuit; and sine wave output current is transmitted to an alternating current power grid through the output end of the voltage doubling rectifying circuit. According to the embodiment, a control strategy of primary power conversion of the micro inverter is realized, the efficiency and the power of the micro inverter are improved, and the cost of the micro inverter is reduced.

Description

Technical Field

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

[0002] Micro inverters help reduce damage to the panels of photovoltaic modules and reduce the impact of inverter failures on photovoltaic grid-connected power generation systems. Compared with centralized inverters, they have high reliability and low power generation costs, and have better application scenarios. However, the current circuit topology of micro inverters is mainly based on flyback circuit topology, which is limited by the volume of the transformer core and the switching frequency, and has low power and efficiency. Although the relevant technology uses a two-stage power conversion topology to improve the power and efficiency of micro inverters, it is still difficult to meet the needs of high-power photovoltaic modules and increases the cost of micro inverters.

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

[0004] The circuit topology and control method of a micro inverter provided by the embodiment of the present invention at least solve 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.

[0005] 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:

[0006] 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 to receive the current input by the photovoltaic module;

[0007] A voltage doubler rectifier circuit comprises a switch bridge arm and a capacitor bridge arm connected in parallel; the voltage doubler 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 boost; wherein the output end of the voltage doubler rectifier circuit is used to transmit a sinusoidal output current to an AC power grid.

[0008] 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.

[0009] In some of the 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.

[0010] In some of the 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 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 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.

[0011] In some of the 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.

[0012] In some of the 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 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.

[0013] In some of the embodiments, 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.

[0014] In some of the 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 sixth 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 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; 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 switch tube, and the parasitic diode of the sixth switch tube in sequence.

[0015] In some of the 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.

[0016] In some of the 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 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.

[0017] 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 switch tube and a second switch 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.

[0018] 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 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.

[0019] 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.

[0020] 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.

[0021] In some of the 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.

[0022] In some of the embodiments, at least one filter inductor is disposed at the output end of the voltage doubler rectifier circuit.

[0023] In some of the embodiments, a common-mode inductor is provided at the output end of the voltage doubler rectifier circuit.

[0024] In order to solve the above problem, one aspect of an embodiment of the present invention provides a micro inverter, including a controller and any circuit topology of the above;

[0025] The controller is used to output a driving signal to control the switching state of multiple switch tubes in the circuit topology, so that the circuit topology transmits a sinusoidal output current to the AC power grid through a primary power conversion.

[0026] In order 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 comprises:

[0027] Detect the maximum power value of the photovoltaic module and receive the current input by the photovoltaic module;

[0028] Obtaining the grid voltage value in the AC 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 on and off of multiple switch 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;

[0029] A sinusoidal output current is transmitted to the AC power grid through the output end of the voltage doubler rectifier circuit.

[0030] In some embodiments, the steps of controlling the on and off of a plurality of switch 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:

[0031] 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 are determined, and the on and off of multiple switch tubes in the micro inverter are alternately controlled 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.

[0032] 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:

[0033] Obtaining a grid voltage value in the AC grid, and determining a current value of an output current according to the grid voltage value and a maximum power value of a photovoltaic module;

[0034] 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.

[0035] In some embodiments, the steps of controlling the on and off of a plurality of switch tubes in a resonant circuit and a voltage doubler rectifier circuit in a 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:

[0036] Control the on and off of multiple switch tubes in the resonant circuit, and let the current input by the photovoltaic module and the resonant cavity current in the resonant circuit flow through the turned-on switch 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 switch 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.

[0037] In some of the 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.

[0038] In some of the embodiments, the steps of controlling the on and off of a plurality of switch 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:

[0039] If the sine wave period is the positive half period of the sine wave, the switching frequencies of 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.

[0040] In some of the embodiments, if the sine wave period is the positive half period 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 closed, 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 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; 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.

[0041] In some of the embodiments, if the sine wave period is the positive half period 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 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.

[0042] In some of the embodiments, if the sine wave period is the positive half period 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 closed, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controls the first switching tube and the fourth switching tube to be turned on to form a fourth conduction current loop, and generates an induced current in the voltage doubler rectifier circuit, controls the fifth switching tube and the sixth switching tube 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.

[0043] In some embodiments, the steps of controlling the on and off of a plurality of switch 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:

[0044] 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 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.

[0045] In some of the embodiments, 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 closed, 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.

[0046] In some of the embodiments, if the sine wave period is the negative half period 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 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.

[0047] In some of the embodiments, 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 third switch tube and the second switch tube in the resonant circuit are controlled to be closed, 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.

[0048] In some of the embodiments, the working state of the multiple switch tubes is a soft switching state.

[0049] 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, and when the instructions are executed by the processor, the processor executes a control method according to any of the above micro inverters.

[0050] 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.

[0051] 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 closing of multiple switch 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 technology, and realizes the micro-inverter output sinusoidal AC grid-connected function only through 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.

[0052] The details of one or more embodiments of the invention are set forth in the following drawings and description so that other features, objects, and advantages of the invention are more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order 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 prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other embodiments can be obtained based on these drawings without creative work.

[0054] Figure 1 Schematic diagram of a circuit topology of a micro inverter according to an embodiment of the present invention.

[0055] Figure 2 Schematic diagram of a circuit topology of a micro inverter according to another embodiment of the present invention.

[0056] Figure 3Schematic diagram of a circuit topology of a micro inverter according to another embodiment of the present invention.

[0057] Figure 4 Schematic diagram of a circuit topology of a micro inverter according to another embodiment of the present invention.

[0058] Figure 5 Schematic diagram of a circuit topology of a micro inverter according to another embodiment of the present invention.

[0059] Figure 6 Schematic diagram of a circuit topology of a micro inverter according to another embodiment of the present invention.

[0060] Figure 7 It is a flowchart of a control method for a micro inverter provided in one embodiment of the present invention.

[0061] Figure 8a yes Figure 7 A schematic diagram of current flow directions of the first conduction current loop and the first induction current loop during the positive half cycle of the sine wave in the control method shown;

[0062] Figure 8b yes Figure 7 A schematic diagram of current flow directions of 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;

[0063] Figure 8c yes Figure 7 A schematic diagram of current flow directions of the third conduction current loop and the third induction current loop during the positive half cycle of the sine wave in the control method shown;

[0064] Figure 8d yes Figure 7 A schematic diagram of current flow directions of the fourth conduction current loop and the fourth induction current loop during the positive half cycle of the sine wave in the control method shown;

[0065] Figure 8e yes Figure 7 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;

[0066] Figure 8f yes Figure 7 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;

[0067] Figure 8g yes Figure 7 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;

[0068] Figure 8h yes Figure 7 Schematic diagram of current flow 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.

[0069] Fig. 9 Schematic diagram of the structure of the electronic device of this embodiment. DETAILED DESCRIPTION

[0070] Embodiments of the present embodiment will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present embodiment are shown in the accompanying drawings, it should be understood that the present embodiment can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein, which are instead provided for a more thorough and complete understanding of the present embodiment. It should be understood that the drawings and embodiments of the present embodiment are only for exemplary purposes and are not intended to limit the scope of protection of the present embodiment.

[0071] The current circuit topology of micro inverters is mainly based on the flyback circuit topology, and the secondary side of the transformer converts the output current into AC through a folding circuit. This circuit topology is limited by the volume of the transformer core and the switching frequency, and it is difficult to increase the power, and the efficiency of the inverter 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, which makes it difficult for the efficiency of the micro inverter to exceed 96%. That is, although the power and efficiency of the micro inverter 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.

[0072] In order to solve the above problems, an embodiment of the present invention provides a circuit topology of a micro inverter, such as Figure 1 As shown, the circuit topology of the micro inverter mainly 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 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 doubler rectifier circuit includes a switch bridge arm and a capacitor bridge arm connected in parallel; the voltage doubler 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 doubler rectifier circuit to form an induced current loop and realize multiple voltage boost; wherein the output end of the voltage doubler rectifier circuit is used to transmit a sinusoidal output current to the AC power grid.

[0073] Through the above-mentioned micro-inverter topology structure, the micro-inverter can transmit sinusoidal AC power to the AC power 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.

[0074] In some of the embodiments, Figure 1 As shown, 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.

[0075] In some of the 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 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 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 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. 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 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.

[0076] In some of the embodiments, 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. 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 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 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; 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 switch tube, and the parasitic diode of the sixth switch 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 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.

[0077] The circuit topology of the micro-inverter provided by the embodiment of the present invention alternately controls the conduction and closing of multiple switch 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 doubler rectifier circuit, respectively. Accordingly, it is achieved that sinusoidal AC power can be transmitted to the AC power grid through only one-stage power conversion, which reduces the complexity of the circuit topology of the micro-inverter, 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, so that it can meet the needs of high-power photovoltaic modules and expand the applicable scenarios of the micro-inverter.

[0078] In some of the embodiments, Figure 2 As shown, 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 switch tube Q1 and a second switch tube Q2 connected in series;

[0079] 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 of the embodiments, Figure 3 As shown, when the above-mentioned 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 inductance Lr, an excitation inductance 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 switch tubes all work in a soft switching state through resonance, which effectively reduces the switching loss of the switch tube and improves the power of the micro inverter.

[0082] In some of the embodiments, Figure 1 As shown, the switch bridge arm in the above-mentioned 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 switch bridge arm and the lower 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 switch bridge arm and the bidirectional switch function of the lower switch bridge arm.

[0084] In some of the embodiments, Figure 1 As shown, 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 a plurality of capacitor sub-bridge arms connected in parallel, a first capacitor sub-bridge arm among the plurality of 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. Figure 4 As shown, 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 one 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 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. Figure 1-Figure 3 FIG. 1 shows a schematic diagram of a circuit topology in which a filter inductor Lg is provided at the output end of the voltage doubler rectifier circuit; Figure 5 Schematic diagram of a circuit topology in which two filter inductors Lg1 and Lg2 are arranged in a voltage doubler rectifier circuit is shown in FIG.

[0088] In some embodiments, a common-mode inductor is provided at the output end of the voltage doubler rectifier circuit. Figure 4 , Figure 6 A schematic diagram of a circuit topology in which a common-mode inductor is arranged at the output end of a voltage doubler rectifier circuit is shown.

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

[0090] In some of the 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 topological structure of the micro-inverter provided in the 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 realize 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. The micro-inverter can meet the requirement of transmitting sinusoidal AC power to the AC power grid through only one-stage power conversion topology, which reduces the complexity of the micro-inverter circuit topology, reduces the volume of the micro-inverter, reduces the cost of the micro-inverter caused by the device arrangement of the two-stage power conversion topology, and 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.

[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 transmits a sinusoidal output current to the AC power grid via a primary power conversion.

[0093] The embodiment of the present invention also provides a control method for a micro inverter, wherein the micro inverter adopts any of the above circuit topologies, such as Figure 7 As shown, in the process of transmitting a sinusoidal output current to an AC power grid, the control method of the micro-inverter provided by the embodiment of the present invention mainly includes:

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

[0095] Step S702, obtain the grid voltage value in the AC power grid, determine the sinusoidal wave period corresponding to the output current according to the grid voltage value and the maximum power value of the photovoltaic component, and control the on and off of multiple switch 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, to charge the second capacitor and the third capacitor in the capacitive bridge arm of the voltage doubler rectifier circuit.

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

[0097] Through the above-mentioned settings, 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 component inputs current, the conduction and closing of the switch tube are controlled to adjust the switching frequency, so as to realize the circuit flipping within the sinusoidal wave cycle, and then output sinusoidal alternating current to the AC power grid, thereby realizing the function of the micro-inverter to realize AC grid connection by only one power conversion, improving the power and efficiency of the micro-inverter, reducing the cost of the micro-inverter, making the control method of the above-mentioned micro-inverter applicable to high-power photovoltaic components, 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 sinusoidal AC power through a micro-inverter through a primary conversion power topology to supply power to the AC power grid, thereby improving the power of the micro-inverter and realizing the grid-connected function of the micro-inverter.

[0099] Among them, in step S702 provided in the embodiment of the present invention, the grid voltage value in the AC power grid is obtained, and the step of determining the sinusoidal wave period corresponding to the output current according to 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 according to the grid voltage value and the maximum power value of the photovoltaic component; if the current value is greater than 0, it is determined 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, it is determined 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 micro-inverter is determined, which is helpful for controlling the conduction and shutdown of multiple switching tubes in the micro-inverter based on the sine wave period. That is, by controlling the switching frequency of the switching tube, the current circuit flipping within the sine wave period is realized to output sinusoidal AC power that meets the needs 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 closing 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 the negative half-cycle of the sine wave corresponding to the sine wave cycle of the output current, and alternately controlling the conduction and closing of multiple switching tubes in the micro-inverter according to the positive half-cycle 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.

[0102] According to a specific implementation of an embodiment of the present invention, when the sinusoidal wave period corresponding to the output current is in the positive half-period of the sinusoidal wave, the conduction and closing of multiple switching tubes in the micro-inverter are controlled to form a positive half-period conduction current loop and a positive half-period inductive current loop in the resonant circuit and the voltage doubler rectifier circuit, respectively; when the sinusoidal wave period of the output current is in the negative half-period of the sinusoidal wave, the conduction and closing of multiple switching tubes in the micro-inverter are controlled to form a negative half-period conduction current loop and a negative half-period 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 correspondingly, 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 conduction current loop, and correspondingly, 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 of the sine wave and the negative half-cycle of the sine wave corresponding to the output current, the conduction and closing of multiple switch 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 realize the current circuit reversal of the output current, and then realize the current circuit reversal of the output current within a sine wave cycle, so that the sine wave AC can be transmitted to the AC power grid only through one-stage power conversion, thereby improving the power and efficiency of the micro-inverter.

[0103] In some of the embodiments, the above-mentioned steps of controlling the conduction and closing of multiple 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 include: controlling the conduction and closing of multiple switch tubes in the resonant circuit, and sequentially allowing the current input by the photovoltaic module and the resonant cavity current in the resonant circuit to flow through the conduction switch tube to form a flipped conduction current loop, and generating an induction current in the voltage doubler rectifier circuit, and controlling the conduction and closing of multiple switch tubes 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 is the same as the switch tube through which the conduction current flows in the resonant circuit, 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, 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 realizes current reversal, thereby realizing that sinusoidal AC can be transmitted to the AC power grid only through one-stage power conversion.

[0105] In some of the embodiments, if the sine wave period is the positive half period 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 switch tube and the fourth switch tube in the resonant circuit are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controls the third switch tube and the second switch tube in the resonant circuit to be turned on to form a second conduction current loop, generates an induced current in the voltage doubler rectifier circuit, controls the seventh switch tube and the eighth switch 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 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; and 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. When 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. 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 switch tube and the second switch tube in the resonant circuit are 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 a fourth conduction current loop, generates an induced current in the voltage doubler rectifier circuit, controls the fifth switch tube and the sixth switch tube 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.

[0106] Figure 8a , Figure 8b , Figure 8c , Figure 8d The current flow diagram of the conducting current loop and the inductive current loop in the circuit topology of the micro inverter in the positive half cycle of the sine wave is shown. In some embodiments thereof, Figure 8a As shown, 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 (PV module) flows through the MOS tube of the first switch tube Q1, the leakage inductance Lr, the primary winding of the winding transformer T1, the resonant capacitor Cr, and the MOS tube of the fourth switch tube Q4 to form a first 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 end of the secondary side of the winding transformer T1, passes through the MOS tube of the sixth switch tube Q6, the parasitic diode of the fifth switch tube Q5, and the second capacitor C2, and then flows back to the opposite-name end of the secondary winding of the winding transformer T1 to form a first induced current loop. Figure 8b As shown, when the first switch tube Q1 and the fourth switch tube Q4 in the resonant circuit are turned off, the current in the resonant cavity drives the third switch tube Q3 and the second switch tube Q2 to turn on, and the conduction current passes through the parasitic diode of the third switch tube Q3, the DC bus capacitor C1, the parasitic diode of the second switch tube 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 end of the secondary winding of the winding transformer T1, passes through the third capacitor C3, the MOS tube of the eighth switch tube Q8, and the parasitic diode of the seventh switch tube Q7, and returns to the same end of the secondary winding of the winding transformer T1, forming a second induced current loop. Figure 8c As shown, after the resonant cavity current is reduced to zero, the current input by the photovoltaic module passes through the MOS tube of the third switch tube Q3, Cr, the primary winding of the winding transformer T1, Lr, the MOS tube of the second switch tube Q2, and the first capacitor C1 to form a third conduction current loop; in this process, the induced current flows out from the opposite end of the secondary winding of the winding transformer T1, passes through the third capacitor C3, the MOS tube of the eighth switch tube Q8, and the parasitic diode of the seventh switch tube Q7, and returns to the same end of the secondary winding of the winding transformer T1, forming a third induced current loop. Figure 8d As shown, 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, and 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 end of the secondary side of the winding transformer T1, passes through the MOS tube 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 end of the secondary winding of the winding transformer T1, forming a fourth induced current loop.

[0107] In some of the embodiments, if the sine wave period is the negative half period of the sine wave, the steps of controlling the switching frequency of multiple switch tubes in the circuit topology according to the frequency of the sine wave are as follows: when the first switch tube and the fourth switch 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, and controls the seventh switch tube and the eighth switch 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 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. When the first switch tube and the fourth switch tube in the resonant circuit are turned off, the resonant cavity current in the resonant circuit feeds the first capacitor on the DC side bus, controls the third switch tube and the second switch tube in the resonant circuit to be turned on to form a sixth conduction current loop, generates an induced current in the voltage doubler rectifier circuit, controls the fifth switch tube and the sixth switch tube in the voltage doubler rectifier circuit 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; and 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. 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. When the third switch tube and the second switch tube in the resonant circuit are 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, 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.

[0108] Figure 8e , Figure 8f , Figure 8g , Figure 8h The current flow diagram of the conduction current loop and the induction current loop in the micro inverter circuit topology during the negative and positive half cycles of the sine wave is shown. In some embodiments, Figure 8e As shown, 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 tube of the first switch tube Q1, the leakage inductance Lr, the primary winding of the winding transformer T1, the resonant capacitor Cr, and the tube of the fourth switch tube Q4, and returns to the first capacitor C1 on the DC side 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 end of the secondary side of the winding transformer T1, passes through the MOS tube 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 end of the secondary winding of the winding transformer T1 to form a fifth induced current loop. Figure 8f As shown, when the first switch tube Q1 and the fourth switch tube Q4 in the resonant circuit are turned off, the current in the resonant cavity drives the third switch tube Q3 and the second switch tube Q2 to turn on, and the conduction current flows through the parasitic diode of the second switch tube Q2, Cr, the primary winding of the winding transformer T1, Lr, and the parasitic diode of the third switch tube Q3 to form a sixth conduction current loop; at the same time, the induced current flows out from the opposite end of the secondary winding of the winding transformer T1, passes through the second capacitor C2, the MOS tube of the fifth switch tube Q5, and the parasitic diode of the sixth switch tube Q6, and returns to the same end of the secondary winding of the winding transformer T1, forming a sixth induced current loop. Figure 8g As shown, after the resonant cavity current is reduced to zero, the current input by the photovoltaic module flows through the MOS tube of the third switch tube Q3, Cr, the primary winding of the winding transformer T1, Lr, the MOS tube of the second switch tube Q2, and returns to the first capacitor C1 to form the seventh conduction current loop; in this process, the induced current flows out from the opposite end of the secondary winding of the winding transformer T1, passes through the second capacitor C2, the MOS tube of the fifth switch tube Q5, and the parasitic diode of the sixth switch tube Q6, and returns to the same end of the secondary winding of the winding transformer T1, forming the seventh induced current loop. Figure 8h As shown, 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 be turned on, and 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 end of the secondary side of the winding transformer T1, passes through the MOS tube 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 end of the secondary winding of the winding transformer T1, forming an eighth induced current loop.

[0109] Through the above settings, after the photovoltaic module inputs current, the on and off of the switch tube is controlled to adjust the switching frequency, so as to realize the current circuit reversal within the sine wave cycle, and then output sinusoidal AC power to the AC power grid, realizing the function of the micro inverter to achieve AC grid connection by only one power conversion, improving the power and efficiency of the micro inverter and reducing the cost of the micro inverter.

[0110] In some of the embodiments, the working state of the above-mentioned multiple switch tubes is a soft switching state.

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

[0112] The control method of the above-mentioned micro-inverter provided in the embodiment of the present invention detects the maximum power value of the photovoltaic component and receives the current input by the photovoltaic component; obtains the grid voltage value in the AC power grid, determines the sinusoidal wave period corresponding to the output current according to the grid voltage value and the maximum power value of the photovoltaic component, and controls the conduction and closing of multiple switch 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 technology, and realizes the micro-inverter output sinusoidal AC grid-connected function only through one-stage power conversion, effectively improves the power and efficiency of the micro-inverter, expands the applicable scenarios of the micro-inverter, and reduces the cost of the micro-inverter due to the reduction of the device layout required for the multi-stage power conversion topology.

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

[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 execute 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 the computer program, when executed by a processor of a computer, is used to enable the computer to execute the method of the embodiment of the present invention.

[0116] refer to Fig. 9 , a block diagram of an electronic device that can be used as a 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. Electronic devices are intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices 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] like Fig. 9 As shown, 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, the ROM 902, and the 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 in 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 that can input information to the electronic device, and the input unit 906 can receive input digital or character information, and generate key signal input related to user settings and / or function control of the electronic device. The output unit 907 can be any type of device that can present information, and can 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 can include but is not limited to a disk, an optical disk. The communication unit 909 allows the electronic device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks, and can 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 running 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 stored in a ROM.

[0120] 902 and / or the communication unit 909 are loaded and / or installed on the electronic device. In some embodiments, the computing unit 901 can be configured to execute the above method in any other appropriate manner (for example, by means of firmware).

[0121] 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 flow chart and / or block diagram are implemented. The computer programs may be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0122] In the context of an embodiment of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable signal medium may 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 may 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.

[0123] It should be noted that the term "including" and its variations used in the embodiments of the present invention are open inclusions, that is, "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"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "multiple" mentioned in the embodiments of the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless the context clearly indicates otherwise, it should be understood as "one or more".

[0124] The various steps described in the method implementation methods provided in the embodiments of the present invention may be performed in different orders and / or in parallel. In addition, the method implementation methods may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0125] 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 refer to each other. In particular, for the device, equipment, and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts refer to the partial description of the method embodiment.

[0126] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the attached 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, 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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