Solar micro inverter circuit

Abstract

The utility model discloses a solar micro inverter circuit, which comprises a microcontroller, an auxiliary power supply, a first PV input module, a second PV input module, a first interleaving flyback circuit module, a second interleaving flyback circuit module and a full-bridge unfolding circuit module, the microcontroller is connected with the first PV input module, the second PV input module, the first interleaving flyback circuit module, the second interleaving flyback circuit module and the full-bridge unfolding circuit module. According to the utility model, the two PV input modules are mutually independent, the use of the other PV input module is not affected when one PV input module is damaged, the SCR + Mos structure is used in the scheme, the circuit structure is simple, the switch works at power frequency, and the loss is mainly conduction loss.

Description

Technical Field

[0001] The present disclosure relates to the technical field of solar inverters, and particularly to a solar micro-inverter circuit. Background Art

[0002] Solar micro-inverters are mainly used to convert direct current (DC) generated by photovoltaic panels into alternating current (AC) for power supply or grid connection. They are mainly aimed at photovoltaic application scenarios such as small residential photovoltaic systems and photovoltaic systems with irregular layouts, where the installation positions of the panels are relatively scattered or face different directions. Each panel provides independent maximum power point tracking (MPPT), thereby improving the power generation efficiency of the overall system.

[0003] In existing products, PV1 and PV2 are mostly connected in parallel, and the high-voltage bus output by the high-frequency transformer is the same one, so the two PV inputs cannot be independent of each other. When one of the PVs fails, the entire machine will malfunction.

[0004] In existing products, the latter-stage full bridge is mostly a high-frequency switch, and its losses are divided into switching losses and conduction losses, and the control is relatively complex. Summary of the Utility Model

[0005] The present disclosure provides a solar micro-inverter circuit to solve one of the technical problems recognized by the inventors.

[0006] The present disclosure provides a solar micro-inverter circuit, including: a microcontroller, an auxiliary power supply, a first PV input module, a second PV input module, a first interleaved flyback circuit module, a second interleaved flyback circuit module, and a full-bridge unfolding circuit module. The microcontroller is respectively connected to the first PV input module, the second PV input module, the first interleaved flyback circuit module, the second interleaved flyback circuit module, and the full-bridge unfolding circuit module. The first PV input module and the second PV input module are respectively connected to the first interleaved flyback circuit module and the second interleaved flyback circuit module. The first interleaved flyback circuit module and the second interleaved flyback circuit module are respectively connected to the same full-bridge unfolding circuit module. The full-bridge unfolding circuit module is connected to a single-phase power grid, the single-phase power grid is connected to a grid voltage detection circuit, and the grid voltage detection circuit is connected to the microcontroller. The input end of the auxiliary power supply is respectively connected to the first PV input module and the second PV input module, and the output end of the auxiliary power supply is respectively connected to the microcontroller, the first PV input module, the second PV input module, the first interleaved flyback circuit module, the second interleaved flyback circuit module, and the full-bridge unfolding circuit module.

[0007] Preferably, the first interleaved flyback circuit module includes a transformer T1 and a transformer T2. One end of the transformer T1 is connected to the first PV input module. A decoupling capacitor C1 and a MOS transistor Q3 are connected between the transformer T1 and the first PV input module. The other end of the transformer T1 is connected to the full-bridge unfolding circuit module.

[0008] Preferably, a rectifier diode D1 is connected between the transformer T1 and the full-bridge unfolding circuit module.

[0009] Preferably, the second interleaved flyback circuit module includes a transformer T3 and a transformer T4. One end of the transformer T3 is connected to the second PV input module. A decoupling capacitor C2 and a MOS transistor Q4 are connected between the transformer T3 and the second PV input module. The other end of the transformer T3 is connected to the full-bridge unfolding circuit module.

[0010] Preferably, a rectifier diode D2 is connected between the transformer T3 and the full-bridge unfolding circuit module.

[0011] Preferably, the full-bridge unfolding circuit module includes thyristors SCR1, SCR2, SCR3, SCR4, MOS transistors Q1, Q2 and a relay K1. The anode of the thyristor SCR1 is connected to the third pin of the transformer T1. The cathode of the thyristor SCR1 is connected to the D pole of the MOS transistor Q1. The anode of the thyristor SCR2 is connected to the third pin of the transformer T1. The cathode of the thyristor SCR2 is connected to the D pole of the MOS transistor Q2. The anode of the thyristor SCR3 is connected to the third pin of the transformer T3. The cathode of the thyristor SCR3 is connected to the D pole of the MOS transistor Q1. The anode of the thyristor SCR4 is connected to the third pin of the transformer T3. The cathode of the thyristor SCR4 is connected to the D pole of the MOS transistor Q2. The S poles of the MOS transistors Q1 and Q2 are respectively connected to the fourth pins of the transformers T1 and T3. The D poles of the MOS transistors Q1 and Q2 are respectively connected to one end of the relay K1. The other end of the relay K1 is connected to the single-phase power grid.

[0012] Preferably, an EMI filtering circuit module is provided between the relay K1 and the single-phase power grid.

[0013] The beneficial effects of the present disclosure mainly lie in that: the two PV input modules of the present utility model are independent of each other, and the damage of one path does not affect the use of the other path. And through the structure of SCR+Mos used in this solution, the circuit structure is simple, the switch operates at the power frequency, and the loss is mainly the conduction loss.

[0014] It should be understood that both the foregoing general description and the following detailed description are for purposes of illustration and example only and do not necessarily limit the disclosure. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the subject matter of the disclosure. At the same time, the specification and the drawings are used to explain the principles of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the specific embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present disclosure. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 Schematic diagram of the circuit principle of an embodiment of the present disclosure; DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solutions of the present disclosure in conjunction with the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure.

[0018] All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts fall within the scope of protection of the present disclosure.

[0019] In the description of the present disclosure, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present disclosure. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0020] In the description of the present disclosure, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0021] EMBODIMENT

[0022] Such as Figure 1As shown in the figure, this embodiment provides a solar micro-inverter circuit, including: a microcontroller, an auxiliary power supply, a first PV input module, a second PV input module, a first interleaved flyback circuit module, a second interleaved flyback circuit module, and a full-bridge unfolding circuit module. The microcontroller is respectively connected to the first PV input module, the second PV input module, the first interleaved flyback circuit module, the second interleaved flyback circuit module, and the full-bridge unfolding circuit module. The first PV input module and the second PV input module are respectively connected to the first interleaved flyback circuit module and the second interleaved flyback circuit module. The first interleaved flyback circuit module and the second interleaved flyback circuit module are respectively connected to the same full-bridge unfolding circuit module. The full-bridge unfolding circuit module is connected to a single-phase power grid. The single-phase power grid is connected to a grid voltage detection circuit, and the grid voltage detection circuit is connected to the microcontroller. The input end of the auxiliary power supply is respectively connected to the first PV input module and the second PV input module, and the output end of the auxiliary power supply is respectively connected to the microcontroller, the first PV input module, the second PV input module, the first interleaved flyback circuit module, the second interleaved flyback circuit module, and the full-bridge unfolding circuit module.

[0023] In this embodiment, the first PV input module and the second PV input module are connected to the power supply, and the auxiliary power supply outputs 4 paths of power, which are respectively: the microcontroller drive power supply, the PV side mos tube drive power supply (mos tubes Q3, Q4), the AC side isolation mos tube drive power supply (mos tubes Q1, Q2), and the microcontroller detects the PV power supply. The microcontroller detects the PV voltage and the phase information of the AC side grid voltage. When the working conditions are met, the relay K1 is closed, and the microcontroller drives the PV side and the AC side power tubes according to the phase information. The energy is converted from the PV input through the high-frequency transformer and output from the full-bridge unfolding circuit.

[0024] Specifically, the first interleaved flyback circuit module includes a transformer T1 and a transformer T2. One end of the transformer T1 is connected to the first PV input module. A decoupling capacitor C1 and a mos tube Q3 are connected between the transformer T1 and the first PV input module. The other end of the transformer T1 is connected to the full-bridge unfolding circuit module.

[0025] Further, a rectifier diode D1 is connected between the transformer T1 and the full-bridge unfolding circuit module.

[0026] Specifically, the second interleaved flyback circuit module includes a transformer T3 and a transformer T4. One end of the transformer T3 is connected to the second PV input module. A decoupling capacitor C2 and a mos tube Q4 are connected between the transformer T3 and the second PV input module. The other end of the transformer T3 is connected to the full-bridge unfolding circuit module.

[0027] Further, a rectifying diode D2 is connected between the transformer T3 and the full-bridge unfolding circuit module.

[0028] Specifically, the full-bridge unfolding circuit module includes thyristors SCR1, SCR2, SCR3, SCR4, MOS transistors Q1, Q2 and a relay K1. The anode of the thyristor SCR1 is connected to the third pin of the transformer T1, the cathode of the thyristor SCR1 is connected to the D pole of the MOS transistor Q1, the anode of the thyristor SCR2 is connected to the third pin of the transformer T1, the cathode of the thyristor SCR2 is connected to the D pole of the MOS transistor Q2, the anode of the thyristor SCR3 is connected to the third pin of the transformer T3, the cathode of the thyristor SCR3 is connected to the D pole of the MOS transistor Q1, the anode of the thyristor SCR4 is connected to the third pin of the transformer T3, the cathode of the thyristor SCR4 is connected to the D pole of the MOS transistor Q2. The S poles of the MOS transistors Q1 and Q2 are respectively connected to the fourth pins of the transformers T1 and T3, the D poles of the MOS transistors Q1 and Q2 are respectively connected to one end of the relay K1, and the other end of the relay K1 is connected to the single-phase power grid.

[0029] In this embodiment, when only one path is working, such as when the first PV input module is working. The rectified current rectified by the rectifying diode D1 of the first PV input module passes through the thyristors SCR1, SCR2, MOS transistors Q1, Q2 and is output to the AC. The microcontroller obtains the zero-crossing information of the grid phase through grid voltage sampling, and controls the thyristor SCR1 and the MOS transistor Q2 and the thyristor SCR2 and the MOS transistor Q1 to be alternately turned on, so that the rectified waveform is converted into a sinusoidal output.

[0030] When two paths of PV are working, the rectified currents respectively rectified and output by the rectifying diodes at their respective PV ends. The microcontroller controls the switching of the SCR on the same side of the full bridge and the MOS transistor on the opposite side according to the zero-crossing information of the grid phase. The powers of the two paths of PV are superimposed and output.

[0031] Further, an EMI filtering circuit module is provided between the relay K1 and the single-phase power grid.

[0032] The working principle of the present utility model: Energy is stored through a decoupling capacitor from the PV input module of the solar cell, and a rectified sinusoidal current is output through the interleaved parallel flyback circuit module and the rectifying diode, and is output to the single-phase power grid through the relay K1 via the full-bridge unfolding circuit module.

[0033] Figure 1There are two independent interleaved flyback circuit modules in total. Among them, transformer T1 and T2 form the first interleaved flyback circuit module, and transformer T3 and T4 form the second interleaved flyback circuit module. The first PV input module and the second PV input module share a set of full-bridge de-folding circuit modules. When only the first PV input module works, thyristors SCR1, SCR2 and MOS transistors Q1, Q2 form a full bridge. When both PVs work, the thyristors SCR on the same side of the full bridge and the MOS transistors on the opposite side switch simultaneously.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A solar micro-inverter circuit, characterized in that, Comprising: A microcontroller, an auxiliary power supply, a first PV input module, a second PV input module, a first interleaved flyback circuit module, a second interleaved flyback circuit module, and a full-bridge unfolding circuit module. The microcontroller is respectively connected to the first PV input module, the second PV input module, the first interleaved flyback circuit module, the second interleaved flyback circuit module, and the full-bridge unfolding circuit module. The first PV input module and the second PV input module are respectively connected to the first interleaved flyback circuit module and the second interleaved flyback circuit module. The first interleaved flyback circuit module and the second interleaved flyback circuit module are respectively connected to the same full-bridge unfolding circuit module. The full-bridge unfolding circuit module is connected to a single-phase power grid. The single-phase power grid is connected to a grid voltage detection circuit. The grid voltage detection circuit is connected to the microcontroller. The input end of the auxiliary power supply is respectively connected to the first PV input module and the second PV input module. The output end of the auxiliary power supply is respectively connected to the microcontroller, the first PV input module, the second PV input module, the first interleaved flyback circuit module, the second interleaved flyback circuit module, and the full-bridge unfolding circuit module.

2. The solar micro-inverter circuit according to claim 1, wherein, The first interleaved flyback circuit module includes a transformer T1 and a transformer T2. One end of the transformer T1 is connected to the first PV input module. A decoupling capacitor C1 and a MOS transistor Q3 are connected between the transformer T1 and the first PV input module. The other end of the transformer T1 is connected to the full-bridge unfolding circuit module.

3. The solar micro-inverter circuit according to claim 2, characterized in that, A rectifier diode D1 is connected between the transformer T1 and the full-bridge unfolding circuit module.

4. The solar micro-inverter circuit according to claim 2, wherein, The second interleaved flyback circuit module includes a transformer T3 and a transformer T4. One end of the transformer T3 is connected to the second PV input module. A decoupling capacitor C2 and a MOS transistor Q4 are connected between the transformer T3 and the second PV input module. The other end of the transformer T3 is connected to the full-bridge unfolding circuit module.

5. The solar micro-inverter circuit according to claim 4, characterized in that, A rectifier diode D2 is connected between the transformer T3 and the full-bridge unfolding circuit module.

6. The solar micro-inverter circuit according to claim 4, wherein The full-bridge unfolding circuit module includes thyristors SCR1, SCR2, SCR3, SCR4, MOS transistors Q1, Q2, and relay K1. The anode of thyristor SCR1 is connected to the third pin of transformer T1. The cathode of thyristor SCR1 is connected to the D pole of MOS transistor Q1. The anode of thyristor SCR2 is connected to the third pin of transformer T1. The cathode of thyristor SCR2 is connected to the D pole of MOS transistor Q2. The anode of thyristor SCR3 is connected to the third pin of transformer T3. The cathode of thyristor SCR3 is connected to the D pole of MOS transistor Q1. The anode of thyristor SCR4 is connected to the third pin of transformer T3. The cathode of thyristor SCR4 is connected to the D pole of MOS transistor Q2. The S poles of MOS transistors Q1 and Q2 are respectively connected to the fourth pins of transformers T1 and T3. The D poles of MOS transistors Q1 and Q2 are respectively connected to one end of relay K1. The other end of relay K1 is connected to the single-phase power grid.

7. The solar micro-inverter circuit according to claim 6, characterized in that, An EMI filtering circuit module is provided between relay K1 and the single-phase power grid.

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