Power supply circuit and photovoltaic inverter

Abstract

The utility model provides a power supply circuit and a photovoltaic inverter, which relate to the field of power electronics technology. The above-mentioned power supply circuit is applied to a photovoltaic inverter, wherein the photovoltaic inverter includes an auxiliary power supply module, a control chip and a photovoltaic component, and the power supply circuit is used to supply power to the auxiliary power supply module at night. Among them, the power supply circuit includes: a first relay module, a rectifier module and an anti-surge module; the anti-surge module includes at least one anti-surge component; the anti-surge component includes a thermistor unit and a second relay unit. When the photovoltaic inverter is in the night state, the control chip sends a first control signal to the first relay module, and the control chip sends a second control signal to the second relay unit, so that the first relay module is closed and the second relay unit is closed. The utility model provides a power supply circuit that can ensure the continuous and stable operation of the control chip on the basis of reducing electricity costs.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and in particular to a power supply circuit and a photovoltaic inverter. Background Art

[0002] With the development of power electronics technology, the application of photovoltaic inverters is becoming more and more common, and the requirements for photovoltaic inverters are also getting higher and higher. For example, photovoltaic inverters are required to have a 24-hour monitoring function, that is, it is necessary to ensure that the control chip of the photovoltaic inverter is always in working condition so as to monitor the back-end load at any time.

[0003] In the prior art, two power supply branches are often set up to ensure the continuous operation of the photovoltaic inverter during the day and night. For example, during the day, the photovoltaic inverter uses photovoltaic modules to convert light energy into electrical energy; during the night, the photovoltaic inverter uses the mains to reversely power the photovoltaic inverter. Usually, in order to reduce the current impact during the switching process between day and night, an anti-surge component is often set in the power supply branch corresponding to the night state. Since the entire circuit needs to work for a long time, the anti-surge component will greatly increase the power consumption of the night power supply branch.

[0004] There is an urgent need for a power supply circuit that can ensure continuous and stable operation of the control chip while reducing electricity costs. Utility Model Content

[0005] The utility model aims to provide a power supply circuit and a photovoltaic inverter, which can reduce the electricity cost and ensure the continuous and stable operation of the control chip.

[0006] The utility model provides a technical solution:

[0007] On the one hand, the utility model provides a power supply circuit, which is applied to a photovoltaic inverter. The photovoltaic inverter includes an auxiliary power supply module, a control chip and a photovoltaic component. The auxiliary power supply module is connected to the power supply circuit, the photovoltaic component and the control chip respectively. The power supply circuit is used to supply power to the auxiliary power supply module at night, and the photovoltaic component is used to supply power to the auxiliary power supply module during the day; the power supply circuit includes: a first relay module, a rectifier module and an anti-surge module; the anti-surge module includes at least one anti-surge component; the anti-surge component includes a thermistor unit and a second relay unit;

[0008] The input end of the first relay module is connected to the AC power supply; the output end of the first relay module is connected to the input end of the rectifier module; the output end of the rectifier module is respectively connected to the first end of the thermal unit and the first end of the second relay unit; the second end of the second relay unit and the second end of the thermal unit are respectively connected to the input end of the auxiliary power module; the control end of the first relay module and the control end of the second relay unit are respectively connected to the control chip to switch the conduction status of the first relay module and the second relay unit according to the control signal of the control chip;

[0009] When the photovoltaic inverter is in the night state, the control chip sends a first control signal to the first relay module, and the control chip sends a second control signal to the second relay unit, so that the first relay module is closed and the second relay unit is closed.

[0010] Preferably, the second relay unit includes a second switch sub-unit and a second relay, the control end of the second switch sub-unit is connected to the control chip, the first end of the second switch sub-unit is respectively connected to the first end of the second relay and the second end of the thermistor unit; the second end of the second switch sub-unit is grounded; the second end of the second relay is connected to the first end of the thermistor unit.

[0011] Preferably, the second relay unit further includes a second reverse diode, a first end of the second reverse diode is connected to the first end of the second relay, and a second end of the second reverse diode is respectively connected to the second end of the second relay and the output end of the auxiliary power module.

[0012] Preferably, the second switch subunit includes a second switch tube and a second drive resistor; the control end of the second switch tube is respectively connected to the control chip and the first end of the second drive resistor, and the first end of the second switch tube is respectively connected to the first end of the second relay and the second end of the thermistor unit; the second end of the second switch tube is connected to the second end of the second drive resistor and is grounded.

[0013] Preferably, the second switch subunit further includes a second current limiting resistor, a first end of the second current limiting resistor is connected to the control chip, and a second end of the second current limiting resistor is respectively connected to the control end of the second switch tube and the first end of the second driving resistor.

[0014] Preferably, when the anti-surge module includes multiple anti-surge components, each of the anti-surge components is connected in parallel, one end of the anti-surge components connected in parallel is connected to the output end of the rectifier module, and the other end of the anti-surge components connected in parallel is connected to the input end of the auxiliary power supply module.

[0015] Preferably, the first relay module includes at least one first relay unit, the first relay unit includes a first switch sub-unit and a first relay, the control end of the first switch sub-unit is connected to the control chip, the first end of the first switch sub-unit is connected to the first end of the first relay; the second end of the second switch sub-unit is grounded; the second end of the second relay is connected to the input end of the rectifier module.

[0016] Preferably, when the first relay module includes two first relay units, the first relays in each of the first relay units are connected in series.

[0017] Preferably, when the first relay is a normally closed relay and the second relay is a normally open relay, when the photovoltaic inverter is in a night state, the control chip sends a low-level signal to the first relay module, and the control chip sends a high-level signal to the second relay unit, and the first relay is closed and the second relay is closed.

[0018] In a second aspect, the utility model provides a photovoltaic inverter, which includes an auxiliary power supply module, a control chip, a photovoltaic component and the power supply circuit described in any one of the first aspect above, the auxiliary power supply module is respectively connected to the power supply circuit, the control chip and the photovoltaic component, the power supply circuit is used to supply power to the auxiliary power supply module at night, and the photovoltaic component is used to supply power to the auxiliary power supply module during the day.

[0019] The beneficial effects of a power supply circuit and a photovoltaic inverter provided by the utility model are:

[0020] A power supply circuit is applied to a photovoltaic inverter. The photovoltaic inverter includes an auxiliary power module, a control chip and a photovoltaic module. The auxiliary power module is connected to the power supply circuit, the photovoltaic module and the control chip respectively. The power supply circuit is used to supply power to the auxiliary power module at night, and the photovoltaic module is used to supply power to the auxiliary power module during the day. The power supply circuit includes: a first relay module, a rectifier module and an anti-surge module; the anti-surge module includes at least one anti-surge component; the anti-surge component includes a thermistor unit and a second relay unit. The input end of the first relay module is connected to an AC power supply; the output end of the first relay module is connected to the input end of the rectifier module; the output end of the rectifier module is respectively connected to the first end of the thermistor unit and the first end of the second relay unit; the second end of the second relay unit and the second end of the thermistor unit are respectively connected to the input end of the auxiliary power module; the control end of the first relay module and the control end of the second relay unit are respectively connected to the control chip to switch the conduction status of the first relay module and the second relay unit according to the control signal of the control chip. When the photovoltaic inverter is in the night state, the control chip sends a first control signal to the first relay module, and the control chip sends a second control signal to the second relay unit, and the first relay module is closed and the second relay unit is closed. The utility model provides a power supply circuit and a photovoltaic inverter, which can ensure the continuous and stable operation of the control chip on the basis of reducing electricity costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the structure of a photovoltaic inverter provided by an embodiment of the utility model;

[0023] Figure 2 One of the structural schematic diagrams of the power supply circuit provided in the embodiment of the utility model;

[0024] Figure 3 The second structural diagram of the power supply circuit provided by the embodiment of the utility model;

[0025] Figure 4 A schematic diagram of the structure of a second relay unit provided in an embodiment of the utility model;

[0026] Figure 5 This is a schematic diagram of the circuit principle of the second switch sub-unit in an embodiment of the utility model;

[0027] Figure 6 A schematic diagram of the structure of a first relay unit provided in an embodiment of the utility model;

[0028] Figure 7 This is a schematic diagram of the circuit principle of the first switch sub-unit in an embodiment of the utility model;

[0029] Figure 8 Schematic diagram of the structure of the first relay module in the embodiment of the utility model.

[0030] Icon: 100-photovoltaic inverter; 101-auxiliary power module; 102-control chip; 103-photovoltaic module; 104-power supply circuit; 401-first relay module; 402-rectifier module; 403-anti-surge module; 301-thermal unit; 302-second relay unit; 201-second switch subunit; 500-first relay unit; 501-first switch subunit; 303-anti-surge component; K1-first relay; R1-first drive resistor; R2-first current limiting resistor; DF1-first reverse diode; K2-second relay; DF2-second reverse diode; Q2-second switch tube; R3-second drive resistor; R4-second current limiting resistor. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] In the description of the present invention, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0035] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] As described in the background technology, the prior art often sets up two power supply branches to ensure the continuous operation of the photovoltaic inverter during the day and night. However, the anti-surge components set up to reduce the current impact during the switching process between the day and night states often greatly increase the power consumption of the power supply branch at night due to the long-term operation of the power supply circuit.

[0037] Based on this, this embodiment provides a power supply solution to ensure continuous and stable operation of the control chip while reducing electricity costs.

[0038] The technical solution will be described in detail below.

[0039] Example

[0040] First, please refer to Figure 1 The utility model provides a photovoltaic inverter 100, which includes an auxiliary power module 101, a control chip 102, a photovoltaic component 103 and a power supply circuit 104. The auxiliary power module 101 is connected to the power supply circuit 104, the control chip 102 and the photovoltaic component 103 respectively. The power supply circuit 104 is used to supply power to the auxiliary power module 101 at night, and the photovoltaic component 103 is used to supply power to the auxiliary power module 101 during the day.

[0041] The working principle of the photovoltaic inverter 100 in this embodiment is:

[0042] When it is in the daytime state, the photovoltaic module 103 converts the received light energy into electrical energy to supply power to the auxiliary power module 101, and then the auxiliary power module 101 outputs the working voltage to ensure the stable operation of the control chip 102. When it is in the nighttime state, the power supply circuit 104 supplies power to the auxiliary power module 101 to provide a stable working voltage for the control chip 102.

[0043] Based on the above examples, please refer to Figure 2 The utility model provides a power supply circuit 104 , which includes: a first relay module 401 , a rectifier module 402 and an anti-surge module 403 ; the anti-surge module 403 includes at least one anti-surge component 303 .

[0044] In one possible implementation, please refer to Figure 2 In order to increase the surge resistance, in this embodiment, when the surge resistance module 403 includes multiple surge resistance components, each surge resistance component is connected in parallel, one end of the surge resistance components connected in parallel is connected to the output end of the rectifier module 402, and the other end of the surge resistance components connected in parallel is connected to the input end of the auxiliary power supply module 101. In this embodiment, when the surge resistance module 403 includes two surge resistance components, the surge resistance components can be arranged in series on the positive and negative electrodes of the output voltage of the power supply circuit 104.

[0045] Please refer to Figure 3 The anti-surge component 303 includes a thermistor unit 301 and a second relay unit 302 .

[0046] Among them, the input end of the first relay module 401 is connected to the AC power supply; the output end of the first relay module 401 is connected to the input end of the rectifier module 402; the output end of the rectifier module 402 is respectively connected to the first end of the thermistor unit 301 and the first end of the second relay unit 302; the second end of the second relay unit 302 and the second end of the thermistor unit 301 are respectively connected to the input end of the auxiliary power supply module 101; the control end of the first relay module 401 and the control end of the second relay unit 302 are respectively connected to the control chip 102 to switch the conduction status of the first relay module 401 and the second relay unit 302 according to the control signal of the control chip 102.

[0047] In a possible implementation method, the thermal sensing unit 301 includes at least one thermistor.

[0048] When the photovoltaic inverter 100 is in the night state, the control chip 102 sends a first control signal to the first relay module 401, and the control chip 102 sends a second control signal to the second relay K2 module, so that the first relay module 401 is closed and the second relay unit 302 is closed.

[0049] In this embodiment, since there is no light energy input in night mode, the auxiliary power module 101 will not receive the voltage input from the photovoltaic component 103. At this time, the auxiliary power module 101 provides a stable operating voltage for the control chip 102 based on the voltage input provided by the power supply circuit 104.

[0050] In one possible implementation method, when the photovoltaic inverter 100 is in the night state, after the control chip 102 receives a stable operating voltage, it sends a first control signal to the first relay module 401 and sends a second control signal to the second relay K2 module to close the first relay module 401 and to close the second relay unit 302.

[0051] When in the daytime state, after receiving a stable working voltage, the control chip 102 sends a third control signal to the first relay module 401 to disconnect the first relay module 401 and cut off the current input of the AC power supply. At this time, the photovoltaic inverter 100 is only powered by the photovoltaic module 103.

[0052] It should be noted that when the auxiliary power supply module 101 is switched from the daytime state to the nighttime state, the control chip 102 cannot receive a stable operating voltage. At this time, in order to ensure that the control chip 102 continues to work, it is necessary to wait until the AC power supply supplies power to the auxiliary module, and then the auxiliary module provides the operating voltage to the control chip 102 to send control signals to the first relay module 401 and the second relay unit 302 respectively.

[0053] In a possible implementation method, the first relay module 401 may be a normally closed relay, and the second relay K2 unit may be a normally open relay. For example, when the photovoltaic inverter 100 is switched from the daytime state to the nighttime state, the control chip 102 cannot work normally. At this time, the first relay module 401 is closed and is in a normally closed state. The AC power supply inputs voltage to the photovoltaic inverter 100 through the power supply circuit 104. After the auxiliary power supply module 101 is charged, the control chip 102 is provided with a working voltage to send a low-level signal to the first relay module 401 and a high-level signal to the second relay K2 module. At this time, the first relay module 401 remains closed and the second relay K2 unit is closed. The closing of the second relay K2 unit can short-circuit the thermistor unit 301, so that the current flows through the second relay K2 unit, thereby reducing power consumption.

[0054] In this embodiment, the thermistor 301 only plays a role in reducing surges when the control chip 102 supplies power through the power supply circuit 104, thereby reducing the impact current of the AC power supply when the circuit is connected. After the power supply circuit 104 works stably, the current flows directly through the second relay K2 unit, and the thermistor no longer increases the nighttime loss of the photovoltaic inverter 100 due to continuous operation.

[0055] In this embodiment, please refer to Figure 4 The second relay unit 302 includes a second switch subunit 201 and a second relay K2. The control end of the second switch subunit 201 is connected to the control chip 102. The first end of the second switch subunit 201 is respectively connected to the first end of the second relay K2 and the second end of the thermistor unit 301; the second end of the second switch subunit 201 is grounded; and the second end of the second relay K2 is connected to the first end of the thermistor unit 301.

[0056] Please continue to refer to Figure 4The second relay unit 302 also includes a second reverse diode DF2, a first end of the second reverse diode DF2 is connected to the first end of the second relay K2, and a second end of the second reverse diode DF2 is respectively connected to the second end of the second relay K2 and the output end of the auxiliary power module.

[0057] Among them, the second reverse diode DF2 is connected in parallel with the second relay K2 to protect the second switch subunit 201. When the second switch subunit 201 is turned on, the current output by the auxiliary power module will flow through the coil of the second relay K2 through the second switch subunit 201 to the ground, and the second reverse diode DF2 is reverse biased at this time. When the second switch subunit 201 is turned off, the current output by the auxiliary power module will not change suddenly, and the coil of the second relay K2 will generate a reverse electromotive force, and its current will still flow through the coil of the second relay K2 through the second switch subunit 201 to the ground. At this time, if there is no second reverse diode DF2, the current will be completely superimposed on the second switch subunit 201, and if the voltage is too high, it will cause the second switch subunit 201 to be broken down. On the contrary, after the second reverse diode DF2 is set, when the second switch subunit 201 is turned off, the second reverse diode DF2 is forward biased, and the coil current in the second relay K2 will flow through the first reverse diode DF1 to form a loop to protect the second switch subunit 201.

[0058] In one possible implementation, see Figure 5 The second switch subunit 201 includes a second switch tube Q2 and a second driving resistor R3; the control end of the second switch tube Q2 is respectively connected to the control chip 102 and the first end of the second driving resistor R3, and the first end of the second switch tube Q2 is respectively connected to the first end of the second relay K2 and the second end of the thermistor unit 301; the second end of the second switch tube Q2 is connected to the second end of the second driving resistor R3 and is grounded.

[0059] In this embodiment, the second driving resistor R3 is arranged in parallel between the control end of the second switch tube Q2 and the second end of the second switch tube Q2, and serves as a pull-down resistor to ensure that the voltage of the control end of the second switch tube Q2 is maintained at a stable voltage state, that is, the voltage of the control end of the second switch tube Q2 is pulled to the ground, so that the control end of the second switch tube Q2 can be stabilized in a low level state, and the control end of the second switch tube Q2 is prevented from being in a suspended state when the control chip 102 stops working, thereby avoiding external interference and improving the stability of the power supply circuit 104.

[0060] In order to ensure the stability of the electrical signal on the basis of the above embodiment, in this embodiment, a second filter capacitor C1 may be provided in parallel with the second drive resistor R3, that is, provided between the control end of the second switch tube Q2 and the second end of the second switch tube Q2.

[0061] Please continue to refer to Figure 5 The second switch subunit 201 further includes a second current limiting resistor R4, a first end of which is connected to the control chip 102, and a second end of which is connected to the control end of the second switch tube Q2 and the first end of the second driving resistor R3, respectively. In this embodiment, the second current limiting resistor R4 is arranged in series with the control end of the second switch subunit 201, for example, the control end of the second switch tube Q2, so as to limit the control end voltage of the second switch tube Q2, avoid the second switch subunit 201 being damaged due to excessive control end voltage of the second switch tube Q2, and ensure the stability of the power supply circuit 104.

[0062] In this embodiment, please refer to Figure 6 The first relay module 401 includes at least one first relay unit 500, the first relay unit includes a first switch subunit 501 and a first relay K1, the control end of the first switch subunit 501 is connected to the control chip 102, the first end of the first switch subunit 501 is connected to the first end of the first relay K1; the second end of the second switch subunit 201 is grounded; the second end of the second relay K2 is connected to the input end of the rectifier module 402.

[0063] In one possible implementation, see Figure 7 In order to ensure the stable operation of the first relay K1, the circuit structure of the first switch subunit 501 may be the same as that of the second switch subunit 201, that is, in this embodiment, the first switch subunit 501 may include a first switch tube Q1, a first reverse diode DF1 and / or a first drive resistor R1 and / or a first current limiting resistor R2 and / or a first filter capacitor C2. The working principles and effects of the first reverse diode DF1, the first drive resistor R1, the first current limiting resistor R2 and the first filter capacitor C2 are consistent with those in the above embodiment, and are not described in detail here.

[0064] To avoid the first switch subunit 501 from being damaged, resulting in the inability to power the control chip 102 at night. In this embodiment, the first relay module 401 may include multiple first relay units 500, taking two relay units as an example. Figure 8 When the first relay module 401 includes two first relay units 500, each first relay unit 500 is connected in series. In a possible implementation, when the first relay K1 is a normally closed relay, the power supply end of each first relay K1 is connected to an AC power supply.

[0065] In summary, the utility model provides a power supply circuit and a photovoltaic inverter, wherein the power supply circuit is applied to the photovoltaic inverter, and the photovoltaic inverter includes an auxiliary power supply module, a control chip and a photovoltaic module. The auxiliary power supply module is connected to the power supply circuit, the photovoltaic module and the control chip respectively, the power supply circuit is used to supply power to the auxiliary power supply module at night, and the photovoltaic module is used to supply power to the auxiliary power supply module during the day. Wherein, the power supply circuit includes: a first relay module, a rectifier module and an anti-surge module; the anti-surge module includes at least one anti-surge component; the anti-surge component includes a thermistor unit and a second relay unit. The input end of the first relay module is connected to the AC power supply; the output end of the first relay module is connected to the input end of the rectifier module; the output end of the rectifier module is respectively connected to the first end of the thermistor unit and the first end of the second relay unit; the second end of the second relay unit and the second end of the thermistor unit are respectively connected to the input end of the auxiliary power supply module; the control end of the first relay module and the control end of the second relay unit are respectively connected to the control chip to switch the conduction of the first relay module and the second relay unit according to the control signal of the control chip. When the photovoltaic inverter is in the night state, the control chip sends a first control signal to the first relay module, and the control chip sends a second control signal to the second relay module, and the first relay module is closed and the second relay unit is closed. The utility model provides a power supply circuit and a photovoltaic inverter, which can ensure the continuous and stable operation of the control chip on the basis of reducing electricity costs.

[0066] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A power supply circuit, applied to a photovoltaic inverter, the photovoltaic inverter comprising an auxiliary power supply module, a control chip and a photovoltaic module, the auxiliary power supply module is connected to the power supply circuit, the photovoltaic module and the control chip respectively, the power supply circuit is used to supply power to the auxiliary power supply module at night, and the photovoltaic module is used to supply power to the auxiliary power supply module during the day; characterized in that: The power supply circuit includes: a first relay module, a rectifier module and an anti-surge module; the anti-surge module includes at least one anti-surge component; the anti-surge component includes a thermistor unit and a second relay unit; The input end of the first relay module is connected to the AC power supply; the output end of the first relay module is connected to the input end of the rectifier module; the output end of the rectifier module is respectively connected to the first end of the thermal unit and the first end of the second relay unit; the second end of the second relay unit and the second end of the thermal unit are respectively connected to the input end of the auxiliary power module; the control end of the first relay module and the control end of the second relay unit are respectively connected to the control chip to switch the conduction status of the first relay module and the second relay unit according to the control signal of the control chip; When the photovoltaic inverter is in the night state, the control chip sends a first control signal to the first relay module, and the control chip sends a second control signal to the second relay unit, so that the first relay module is closed and the second relay unit is closed.

2. The power supply circuit according to claim 1, characterized in that: The second relay unit includes a second switch sub-unit and a second relay. The control end of the second switch sub-unit is connected to the control chip. The first end of the second switch sub-unit is respectively connected to the first end of the second relay and the second end of the thermistor unit; the second end of the second switch sub-unit is grounded; and the second end of the second relay is connected to the first end of the thermistor unit.

3. The power supply circuit according to claim 2, characterized in that: The second relay unit also includes a second reverse diode, a first end of the second reverse diode is connected to the first end of the second relay, and a second end of the second reverse diode is respectively connected to the second end of the second relay and the output end of the auxiliary power module.

4. The power supply circuit according to claim 2, characterized in that: The second switch subunit includes a second switch tube and a second drive resistor; the control end of the second switch tube is respectively connected to the control chip and the first end of the second drive resistor, and the first end of the second switch tube is respectively connected to the first end of the second relay and the second end of the thermistor unit; the second end of the second switch tube is connected to the second end of the second drive resistor and is grounded.

5. The power supply circuit according to claim 4, characterized in that: The second switch subunit further includes a second current limiting resistor, a first end of which is connected to the control chip, and a second end of which is respectively connected to the control end of the second switch tube and the first end of the second driving resistor.

6. The power supply circuit according to claim 1, characterized in that: When the anti-surge module includes multiple anti-surge components, each of the anti-surge components is connected in parallel, one end of the anti-surge components connected in parallel is connected to the output end of the rectifier module, and the other end of the anti-surge components connected in parallel is connected to the input end of the auxiliary power module.

7. The power supply circuit according to claim 2, characterized in that: The first relay module includes at least one first relay unit, the first relay unit includes a first switch sub-unit and a first relay, the control end of the first switch sub-unit is connected to the control chip, the first end of the first switch sub-unit is connected to the first end of the first relay; the second end of the second relay is connected to the input end of the rectifier module.

8. The power supply circuit according to claim 7, characterized in that: When the first relay module includes two first relay units, the first relays in the first relay units are connected in series.

9. The power supply circuit according to claim 7, characterized in that: When the first relay is a normally closed relay and the second relay is a normally open relay, When the photovoltaic inverter is in the night state, the control chip sends a low level signal to the first relay module, and the control chip sends a high level signal to the second relay unit, so that the first relay is closed and the second relay is closed.

10. A photovoltaic inverter, characterized in that: The photovoltaic inverter includes an auxiliary power module, a control chip, a photovoltaic component and a power supply circuit as described in any one of claims 1 to 9, the auxiliary power module is connected to the power supply circuit, the control chip and the photovoltaic component respectively, the power supply circuit is used to supply power to the auxiliary power module at night, and the photovoltaic component is used to supply power to the auxiliary power module during the day.

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