Starting auxiliary source circuit of photovoltaic inverter, power supply circuit and photovoltaic inverter

Abstract

The utility model provides a starting auxiliary source circuit of a photovoltaic inverter, a power supply circuit and the photovoltaic inverter. The starting auxiliary source circuit of the photovoltaic inverter comprises a half-wave rectification unit, a full-wave rectification unit and a first one-way conduction unit. An alternating current input end of the full-wave rectification unit is connected with an alternating current source of the starting auxiliary source circuit through the half-wave rectification unit; the direct current output end of the full-wave rectification unit is connected with a direct current bus of the photovoltaic inverter through the first one-way conduction unit; the direct-current output end of the full-wave rectification unit outputs first power supply voltage to the direct-current bus, and the voltage of the direct-current bus serves as starting voltage of the photovoltaic inverter.

Description

Technical Field

[0001] This utility model belongs to the field of photovoltaic inverter technology, and specifically refers to a photovoltaic inverter start-up auxiliary power supply circuit, power supply circuit and photovoltaic inverter. Background Technology

[0002] A photovoltaic (PV) inverter is the core device in a photovoltaic (PV) system. Its main function is to convert the direct current (DC) generated by solar panels into alternating current (AC) for use by household or industrial electrical equipment. A PV inverter has a DC bus, whose voltage is typically several hundred volts. The electrical energy output from PV modules, batteries, the grid, or generators is rectified and boosted before being fed into the DC bus. The PV inverter then converts the DC power on the DC bus back into AC power to supply loads or connect to the grid.

[0003] A photovoltaic (PV) inverter's power circuit typically draws power from the DC bus, steps it down, and outputs +15V, +12V, -12V, and -15V to power its internal components. However, when a PV inverter starts up, there is no voltage on the DC bus, preventing it from drawing power to power its components. Therefore, PV inverters need to draw power from the grid or a generator.

[0004] Therefore, the startup auxiliary circuit of a photovoltaic inverter draws two-phase line voltage from the grid or generator as input. Existing photovoltaic inverters rectify these two-phase line voltages via full-wave rectification before feeding them into the DC bus to charge the bus capacitor. However, at the moment of startup, the DC bus capacitor is approximately short-circuited, and due to the high grid voltage, a large inrush current is easily generated, subjecting the startup auxiliary circuit to significant stress and reducing its reliability and lifespan. Utility Model Content

[0005] The photovoltaic inverter startup auxiliary power supply circuit, power supply circuit, and photovoltaic inverter provided in this application embodiment protect the startup auxiliary power supply circuit and improve its reliability and service life.

[0006] In a first aspect, embodiments of this application provide a startup auxiliary power circuit for a photovoltaic inverter, comprising: a half-wave rectifier unit, a full-wave rectifier unit, and a first unidirectional conduction unit; the AC input terminal of the full-wave rectifier unit is connected to the AC source of the startup auxiliary power circuit through the half-wave rectifier unit; the DC output terminal of the full-wave rectifier unit is connected to the DC bus of the photovoltaic inverter through the first unidirectional conduction unit; the DC output terminal of the full-wave rectifier unit outputs a first supply voltage to the DC bus, and the voltage of the DC bus is used as the startup voltage of the photovoltaic inverter.

[0007] Optionally, it also includes a switching unit; the DC output terminal of the full-wave rectifier unit includes a first DC output terminal and a second DC output terminal; the first DC output terminal of the full-wave rectifier unit is connected to the first terminal of the switching unit through the first unidirectional conduction unit, the second terminal of the switching unit is connected to the positive bus of the DC bus; the third terminal of the switching unit is connected to the second DC output terminal of the full-wave rectifier unit, and the fourth terminal of the switching unit is connected to the negative bus of the DC bus.

[0008] Optionally, the switching unit includes a multi-pole relay and a relay control module; the multi-pole relay includes a driver, a first switch, and a second switch; a first end of the first switch is connected to a first end of the switching unit, and a second end of the first switch is connected to a second end of the switching unit; a first end of the second switch is connected to a third end of the switching unit, and a second end of the second switch is connected to a fourth end of the switching unit; the relay control module is connected to a first end of the driver, and a second end of the driver is connected to a third power supply voltage; the relay control module controls the on / off state of the first switch and the second switch.

[0009] Optionally, the relay control module includes: at least one fourth diode, the anode of the fourth diode being connected to a first end of the driving element, and the cathode of the fourth diode being connected to a second end of the driving element; a first resistor, the first end of which receives a relay control signal; a second resistor, the first end of which is connected to the first end of the first resistor, and the second end of the second resistor being connected to the negative busbar; a first switching transistor, the control electrode of which is connected to the second end of the first resistor, the first electrode of which is connected to the first end of the driving element, and the second electrode of which is connected to the negative busbar, wherein the control electrode of the first switching transistor controls the conduction or de-conduction of the first electrode and the second electrode of the first switching transistor according to the relay control signal.

[0010] Optionally, there are two multi-pole relays, defined as a first multi-pole relay and a second multi-pole relay. The first switching element of the first multi-pole relay is connected to the first terminal of the switching unit. One terminal of the first switching element of the second multi-pole relay is connected to the first switching element of the first multi-pole relay, and the other terminal of the first switching element of the second multi-pole relay is connected to the second terminal of the switching unit. The second switching element of the first multi-pole relay is connected to the third terminal of the switching unit. One terminal of the second switching element of the second multi-pole relay is connected to the second switching element of the first multi-pole relay, and the other terminal of the second switching element of the second multi-pole relay is connected to the fourth terminal of the switching unit. The driving elements of both the first and second multi-pole relays are connected to the first pole of the first switching transistor.

[0011] Optionally, it also includes a surge protection unit; the first DC output terminal is connected to the positive bus of the DC bus via the first unidirectional conduction unit; the second DC output terminal is connected to the negative bus of the DC bus; the first end of the surge protection unit is connected to the first DC output terminal, and the second end of the surge protection unit is connected to the second DC output terminal; the surge protection unit includes a third resistor, a fourth resistor, a first capacitor, and a second capacitor; the first end of the third resistor is connected to the first DC output terminal of the full-wave rectifier unit, the second end of the third resistor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is connected to the second DC output terminal of the full-wave rectifier unit. The output terminals are connected as follows: the first terminal of the first capacitor is connected to the first DC output terminal of the full-wave rectifier unit; the second terminal of the first capacitor is connected to the first terminal of the second capacitor and the second terminal of the first resistor; the second terminal of the second capacitor is connected to the second DC output terminal of the full-wave rectifier unit; the first DC output terminal of the full-wave rectifier unit is connected to the first switching device through the first unidirectional conducting unit, the first unidirectional conducting unit being a fourth diode, the anode of the fourth diode being connected to the first terminal of the first switching device, and the cathode of the fourth diode being connected to the first DC output terminal of the full-wave rectifier unit; wherein, the third resistor and the fourth resistor are both varistors.

[0012] Optionally, the number of full-wave rectifier units is two, defined as a first full-wave rectifier unit and a second full-wave rectifier unit; the number of half-wave rectifier units is two, defined as a first half-wave rectifier unit and a second half-wave rectifier unit; the number of AC sources in the auxiliary startup circuit is two, defined as a first AC source and a second AC source; the AC input terminal of the first full-wave rectifier unit is connected to the first AC source of the auxiliary startup circuit through the first half-wave rectifier unit; the AC input terminal of the second full-wave rectifier unit is connected to the second AC source of the auxiliary startup circuit through the second half-wave rectifier unit; the first DC output terminal of the first full-wave rectifier unit and the first DC output terminal of the second full-wave rectifier unit are connected; the second DC output terminal of the first full-wave rectifier unit and the second DC output terminal of the second full-wave rectifier unit are connected.

[0013] Optionally, the conduction direction of the first half-wave rectifier unit is opposite to that of the second half-wave rectifier unit; the first half-wave rectifier unit is a first diode, the second half-wave rectifier unit is a second diode, and the first unidirectional conduction unit is a third diode.

[0014] Secondly, this application provides a power supply circuit for a photovoltaic inverter, comprising: a first auxiliary power supply circuit, a second auxiliary power supply circuit, and a voltage conversion circuit. The second auxiliary power supply circuit is the starting auxiliary power supply circuit described in the first aspect. The input terminal of the first auxiliary power supply circuit receives the battery voltage, and the output terminal of the first auxiliary power supply circuit is connected to the input terminal of the voltage conversion circuit through a second unidirectional conduction unit. The first auxiliary power supply circuit is used to convert the battery voltage into a second supply voltage. The second auxiliary power supply circuit is used to output a first supply voltage to the DC bus. The DC bus is connected to the input terminal of the voltage conversion circuit through a third unidirectional conduction unit. When the second supply voltage is greater than the bus voltage of the DC bus, the second unidirectional conduction unit is turned on, and the third unidirectional conduction unit is turned off. The voltage conversion circuit converts the second supply voltage into a supply voltage for one or more devices and outputs it. When the bus voltage of the DC bus is greater than the second supply voltage, the second unidirectional conduction unit is turned off, and the third unidirectional conduction unit is turned on. The voltage conversion circuit converts the bus voltage of the DC bus into a supply voltage for one or more devices and outputs it.

[0015] Optionally, the first auxiliary power supply circuit includes a voltage detection circuit and a first flyback circuit; the voltage detection circuit is used to output a feedback signal to the first flyback circuit when the battery voltage is less than a first threshold; the input terminal of the first flyback circuit is connected to the input terminal of the first auxiliary power supply circuit, the output terminal of the first flyback circuit is connected to the output terminal of the first auxiliary power supply circuit, the first flyback circuit converts the battery voltage into the second power supply voltage, and when a low voltage signal is received, the first flyback circuit stops converting the battery voltage into the second power supply voltage.

[0016] Optionally, the voltage conversion circuit includes: a transformer having a primary winding and multiple secondary windings, the first end of the primary winding being connected to the input terminal of the voltage conversion circuit, and the multiple secondary windings respectively outputting device supply voltages; a second switching transistor having its first terminal connected to the second terminal of the primary winding of the transformer; a pulse control circuit having its pulse signal output terminal connected to the control terminal of the second switching transistor, the pulse control circuit and the second terminal of the second switching transistor sharing a common ground; the pulse control circuit is used to output a pulse signal and control the second switching transistor to be turned on or off, so as to control the electrical energy received at the input terminal of the voltage conversion circuit to be converted from the primary winding of the transformer to the secondary winding; a feedback circuit having its input terminal receiving a device supply voltage, its output terminal being connected to the feedback signal terminal of the pulse control circuit and outputting a feedback signal, the pulse control circuit... The control circuit adjusts the duty cycle of the pulse signal according to the feedback signal; a voltage divider circuit is used to divide the voltage when the pulse control circuit is started, so as to provide a start-up voltage for the pulse control circuit; the voltage divider circuit includes a first voltage divider branch and a second voltage divider branch; the first end of the first voltage divider branch is connected to the primary winding of the transformer, and the second end of the first voltage divider branch is connected to the start-up voltage power supply terminal of the pulse control circuit; the first voltage divider branch includes at least two first voltage divider units connected in series, and each first voltage divider unit includes at least two resistors connected in parallel; the first end of the second voltage divider branch is connected to the start-up voltage power supply terminal of the pulse control circuit, and the second end of the second voltage divider branch is grounded; the second voltage divider branch includes at least two second voltage divider units connected in series, and each second voltage divider unit includes at least two resistors connected in parallel.

[0017] Thirdly, this application provides a photovoltaic inverter, including the auxiliary power supply circuit as described in the first aspect, or the power supply circuit as described in the second aspect.

[0018] This application provides a startup auxiliary power supply circuit, a power supply circuit, and a photovoltaic inverter. In the startup auxiliary power supply circuit, the AC power output from the AC source passes through a half-wave rectifier unit, resulting in a half-cycle period without current. This effectively reduces the average input current and decreases the stress on the startup auxiliary power supply circuit. The AC power, after passing through the half-wave rectifier unit, becomes a pulsating DC voltage and then passes through a full-wave rectifier unit and a first unidirectional conduction unit before reaching the DC bus. The structural characteristics of the full-wave rectifier unit prevent current from flowing back into the two-phase line voltage of the power grid used for power extraction, thus providing protection. By combining the half-wave and full-wave rectifier units, while establishing voltage on the DC bus of the photovoltaic inverter, the startup auxiliary power supply circuit is protected, its reliability and lifespan are improved, and backflow into the power grid is prevented. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0020] Figure 1 Schematic diagram of the start-up auxiliary power circuit of the photovoltaic inverter provided in this application Figure 1 ; Figure 2 Schematic diagram of the start-up auxiliary power circuit of the photovoltaic inverter provided in this application Figure 2 ; Figure 3 Schematic diagram of the start-up auxiliary power circuit of the photovoltaic inverter provided in this application Figure 3 ; Figure 4 Schematic diagram of the start-up auxiliary power circuit of the photovoltaic inverter provided in this application Figure 4 ; Figure 5 A circuit diagram of the auxiliary power supply circuit for the photovoltaic inverter provided in this application; Figure 6 A schematic diagram of the power supply circuit of the photovoltaic inverter provided in this application; Figure 7 A circuit diagram of the first auxiliary power source circuit provided in this application; Figure 8 A circuit diagram of the voltage conversion circuit provided in this application.

[0021] The labels in the diagram represent the following: 1. Second auxiliary power supply circuit; 11. Full-wave rectifier unit; 111. First full-wave rectifier unit; 112. Second full-wave rectifier unit; 12. Half-wave rectifier unit; 121. First half-wave rectifier unit; 122. Second half-wave rectifier unit; 13. AC power source; 131. First AC power source; 132. Second AC power source; 14. DC bus; 15. Switching unit; 16. Surge protection unit; 17. First unidirectional conduction unit; 18. Multi-pole relay; 181. First... 182. Multi-pole relay; 183. Second multi-pole relay; 184. Driver; 185. First switch; 186. Second switch; 19. Relay control module; 2. First auxiliary power supply circuit; 21. Voltage detection circuit; 22. First flyback circuit; 3. Voltage conversion circuit; 31. Transformer; 32. Pulse control circuit; 33. Feedback circuit; 34. Voltage divider circuit; 341. First voltage divider branch; 342. Second voltage divider branch; 4. Second unidirectional conduction unit; 5. Third unidirectional conduction unit.

[0022] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments.

[0024] Example 1

[0025] Since there is no voltage on DC bus 14 when the photovoltaic inverter starts up, it cannot draw power from DC bus 14 to start its components. Therefore, the photovoltaic inverter needs to draw power from the grid or generator through an auxiliary power supply circuit. However, the voltage output by the grid or generator is often relatively high, which can easily generate large inrush currents. This puts significant stress on the auxiliary power supply circuit, potentially damaging the lifespan of the components. Therefore, a new auxiliary power supply circuit needs to be designed to solve this problem.

[0026] like Figure 1 As shown, this application embodiment provides a startup auxiliary power circuit for a photovoltaic inverter, including: a half-wave rectifier unit 12, a full-wave rectifier unit 11, and a first unidirectional conduction unit 17; the AC input terminal of the full-wave rectifier unit 11 is connected to the AC source 13 of the startup auxiliary power circuit through the half-wave rectifier unit 12; the DC output terminal of the full-wave rectifier unit 11 is connected to the DC bus 14 of the photovoltaic inverter through the first unidirectional conduction unit 17; the DC output terminal of the full-wave rectifier unit 11 outputs a first supply voltage to the DC bus 14, and the voltage of the DC bus 14 is used as the startup voltage of the photovoltaic inverter.

[0027] Among them, the full-wave rectifier unit 11 refers to a circuit that can achieve full-wave rectification of AC power, including modular full-wave rectifier bridges, bridge rectifier bridges composed of four diodes, etc. The half-wave rectifier unit 12 refers to a circuit that can achieve half-wave rectification of AC power, including those using diodes, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) with body diodes, and IGBTs (Insulated Gate Bipolar Transistors), etc. The first unidirectional conduction unit 17 defines the direction of current flow, conducting in the forward direction and cutting off in the reverse direction. The first unidirectional conduction unit 17 can be a diode, a MOSFET with a body diode, or an IGBT, etc. The AC source 13 refers to a circuit that can generate AC power, or it can refer to the two-phase line voltage obtained after a photovoltaic inverter is connected to the grid or generator. Taking the two-phase line voltage of a three-phase grid as an example, the voltage difference between the two-phase line voltages is 380V, and the two-phase line voltage is equivalent to outputting a sine wave with an amplitude of 380V. The sine wave is first rectified by a half-wave rectifier unit 12, meaning that half a cycle is used in each period, resulting in a half-cycle with no current. This effectively reduces the average input current and decreases the stress on the auxiliary power supply circuit. After passing through the half-wave rectifier unit 12, the sine wave becomes a pulsating DC voltage and then passes through the full-wave rectifier unit 11 and the first unidirectional conduction unit 17 before reaching the DC bus 14. The structural characteristics of the full-wave rectifier unit 11 prevent current from flowing back into the two-phase line voltages of the power grid used for power extraction, thus providing protection. The half-wave rectifier unit 12 can be connected to either of these two line voltages, and the conduction direction is unrestricted; that is, the beneficial technical effects of this embodiment can be achieved whether the positive or negative half-cycle is used. This embodiment, by combining the half-wave rectifier unit 12 and the full-wave rectifier unit 11, establishes voltage for the DC bus 14 of the photovoltaic inverter while protecting the auxiliary power supply circuit and preventing backflow into the power grid, demonstrating excellent beneficial effects.

[0028] The power circuit of the photovoltaic inverter draws power from the DC bus 14 and converts it to the required voltage to power the various chips. Then, the inverter's drive board connects directly to the grid and draws three-phase power from it. The drive board has a topology circuit composed of power switching transistors. After drawing three-phase power from the grid, the topology circuit converts AC to DC to charge the DC bus 14. When the DC bus 14 voltage exceeds the first supply voltage, the first unidirectional conduction unit 17 is cut off, and the auxiliary power supply circuit no longer supplies current to the DC bus 14. This is because the AC power output from the AC source 13, after half-wave rectification, will produce a higher peak current compared to full-wave rectification. However, the startup time of the photovoltaic inverter is generally short, and this peak current has a relatively small impact on the bus capacitor. After the first unidirectional conduction unit 17 is cut off, the influence of the auxiliary power supply circuit on the bus capacitor is isolated, thus protecting the bus capacitor.

[0029] Example 2

[0030] This embodiment is a further optimization based on Embodiment 1. When the voltage of DC bus 14 exceeds the first supply voltage, the auxiliary power circuit no longer needs to draw power from the grid. Therefore, to ensure the safe operation of the photovoltaic inverter, the connection between the auxiliary power circuit and DC bus 14 needs to be disconnected. Figure 2 As shown, this embodiment also includes a switching unit 15; the DC output terminal of the full-wave rectifier unit 11 includes a first DC output terminal and a second DC output terminal; the first DC output terminal of the full-wave rectifier unit 11 is connected to the first terminal of the switching unit 15 through a first unidirectional conduction unit 17, the second terminal of the switching unit 15 is connected to the positive bus of the DC bus 14; the third terminal of the switching unit 15 is connected to the second DC output terminal of the full-wave rectifier unit 11, and the fourth terminal of the switching unit 15 is connected to the negative bus of the DC bus 14.

[0031] like Figure 3 and Figure 4 As shown, the switching unit 15 includes a multi-pole relay 18 and a relay control module 19. The multi-pole relay 18 includes a driver 183, a first switch 184, and a second switch 185. The first terminal of the first switch 184 is connected to the first terminal of the switching unit 15, and the second terminal of the first switch 184 is connected to the second terminal of the switching unit 15. The first terminal of the second switch 185 is connected to the third terminal of the switching unit 15, and the second terminal of the second switch 185 is connected to the fourth terminal of the switching unit 15. The relay control module 19 is connected to the first terminal of the driver 183, and the second terminal of the driver 183 is connected to a third power supply voltage, i.e., H+12V. The relay control module 19 is used to control the on / off state of the first switch 184 and the second switch 185. The driver 183 of the multi-pole relay 18 contains a coil. If the multi-pole relay 18 is a normally closed relay, then when the coil is energized, the first switch 184 disconnects the connection between the first and second terminals of the switching unit 15, and the second switch 185 disconnects the connection between the third and fourth terminals of the switching unit 15; conversely, they connect. If the multi-pole relay 18 is a normally open relay, when the coil is energized, the first switch 184 connects the connection between the first and second terminals of the switching unit 15, and the second switch 185 connects the connection between the third and fourth terminals of the switching unit 15; conversely, they disconnect.

[0032] The relay control module 19 includes at least one fourth diode D4, the anode of the fourth diode D4 being connected to the first end of the drive 183, and the cathode of the fourth diode D4 being connected to the second end of the drive 183; the fourth diode D4 is used to discharge the coil current of the multi-pole relay 18.

[0033] The first resistor R1 receives the relay control signal at its first end; the relay control signal is issued by the control chip of the photovoltaic inverter, and existing technology can be used to obtain the voltage of the DC bus 14 from the control chip.

[0034] The second resistor R2 has its first end connected to the first end of the first resistor R1, and its second end connected to the negative bus. This is to ensure that the entire circuit can operate under the same reference potential, which is an existing principle and will not be elaborated upon in this embodiment.

[0035] The first switching transistor Q1 has its control electrode connected to the second terminal of the first resistor R1, its first electrode connected to the first terminal of the driving device 183, and its second electrode grounded. The control electrode controls the conduction or cutoff of the first and second electrodes according to the relay control signal. The first switching transistor Q1 can be a transistor or a MOSFET. If Q1 is a MOSFET, then its first electrode is the drain, its second electrode is the source, and its control electrode is the gate. If Q1 is an NPN transistor (NPN bipolar junction transistor), then its first electrode is the collector, its second electrode is the emitter, and its control electrode is the base. The same logic applies to PNP transistors (PNP bipolar junction transistors) and IGBTs (Insulated Gate Bipolar Transistors).

[0036] When the internal components of the photovoltaic inverter begin to operate normally, and the photovoltaic inverter's drive board can draw power from the grid and supply it to the DC bus 14, the control chip sends a relay control signal to control the multi-pole relay 18 to disconnect, thereby physically cutting off the connection between the auxiliary power supply circuit and the DC bus 14. Alternatively, the connection can be cut off without waiting for the DC bus 14 voltage to exceed the first supply voltage. In this case, the first unidirectional conduction unit 17 mainly serves to prevent backflow.

[0037] like Figure 3 As shown, AC source 13 includes grid connection terminals, namely Grid-R1 and Grid-S1, with a thermistor PTC47R connected in series at each terminal.

[0038] Furthermore, such as Figure 5 As shown, there are two multi-pole relays 18, which are defined as the first multi-pole relay 181 and the second multi-pole relay 182.

[0039] The first switching element 184 of the first multi-pole relay 181 is connected to the first end of the switching unit 15, one end of the first switching element 184 of the second multi-pole relay 182 is connected to the first switching element 184 of the first multi-pole relay 181, and the other end of the first switching element 184 of the second multi-pole relay 182 is connected to the second end of the switching unit 15.

[0040] The second switch 185 of the first multi-pole relay 181 is connected to the third terminal of the switch unit 15. One end of the second switch 185 of the second multi-pole relay 182 is connected to the second switch 185 of the first multi-pole relay 181, and the other end of the second switch 185 of the second multi-pole relay 182 is connected to the fourth terminal of the switch unit 15.

[0041] The driving element 183 of the first multi-pole relay 181 and the driving element 183 of the second multi-pole relay 182 are both connected to the first pole of the first switching transistor Q1.

[0042] Two multi-pole relays 18 are connected in series, connecting together when needed and disconnecting together when needed. Assuming the first multi-pole relay 181 fails, the second multi-pole relay 182 can continue to operate, ensuring safety. In this embodiment, the multi-pole relays 18 are preferably normally closed relays.

[0043] Example 3

[0044] This embodiment is a further optimization based on Embodiment 2, such as... Figure 5 As shown, this embodiment also includes a surge protection unit 16; the DC output terminal of the full-wave rectifier unit 11 includes a first DC output terminal and a second DC output terminal; the first DC output terminal of the full-wave rectifier unit 11 is connected to the positive bus of the DC bus 14 through a first unidirectional conduction unit 17; the second DC output terminal of the full-wave rectifier unit 11 is connected to the negative bus of the DC bus 14; the first end of the surge protection unit 16 is connected to the first DC output terminal, and the second end of the surge protection unit 16 is connected to the second DC output terminal of the full-wave rectifier unit 11.

[0045] The surge protection unit 16 includes a third resistor R3, a fourth resistor R4, a first capacitor C1, and a second capacitor C2. The first end of the third resistor R3 is connected to the first DC output terminal of the full-wave rectifier unit 11, the second end of the third resistor R3 is connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected to the second DC output terminal of the full-wave rectifier unit 11. The first end of the first capacitor C1 is connected to the first DC output terminal of the full-wave rectifier unit 11, the second end of the first capacitor C1 is connected to the first end of the second capacitor C2 and the second end of the first resistor R1, and the second end of the second capacitor C2 is connected to the second DC output terminal of the full-wave rectifier unit 11. The first DC output terminal of the full-wave rectifier unit 11 is connected to the first switch 184 through a first unidirectional conduction unit 17, which is a third diode D3. The anode of the third diode D3 is connected to the first terminal of the first switch 184, and the cathode of the third diode D3 is connected to the first DC output terminal of the full-wave rectifier unit 11.

[0046] The surge protection unit 16 absorbs instantaneous voltage spikes generated by rectification commutation, power grid fluctuations, or switching actions in the circuit, suppressing voltage oscillations and reducing the voltage change rate, thus protecting downstream circuits from surge impacts. The third resistor R3 and the fourth resistor R4 are both varistors. When the first unidirectional conduction unit 17 is turned off or the switching unit 15 is opened, the two-phase line voltages of the power grid remain normal and do not exceed the varistor voltage values ​​of the third resistor R3 and the fourth resistor R4, effectively making them an open circuit. The full-wave rectifier unit 11 also no longer receives voltage from the power grid, thus protecting and starting the auxiliary power supply circuit.

[0047] Example 4

[0048] This embodiment is a further optimization based on Embodiment 1, Embodiment 2, or Embodiment 3, such as... Figure 5 As shown, there are two full-wave rectifier units 11, which are defined as the first full-wave rectifier unit 111 and the second full-wave rectifier unit 112, respectively; there are two half-wave rectifier units 12, which are defined as the first half-wave rectifier unit 121 and the second half-wave rectifier unit 122, respectively; and there are two AC sources 13 for starting the auxiliary power supply circuit, which are defined as the first AC source 131 and the second AC source 132, respectively.

[0049] The AC input terminal of the first full-wave rectifier unit 111 is connected to the first AC source 131 of the auxiliary power supply circuit through the first half-wave rectifier unit 121; the AC input terminal of the second full-wave rectifier unit 112 is connected to the second AC source 132 of the auxiliary power supply circuit through the second half-wave rectifier unit 122; the first DC output terminal of the first full-wave rectifier unit 111 is connected to the first DC output terminal of the second full-wave rectifier unit 112; the second DC output terminal of the first full-wave rectifier unit 111 is connected to the second DC output terminal of the second full-wave rectifier unit 112.

[0050] The first half-wave rectifier unit 121 is the first diode D1, the second half-wave rectifier unit 122 is the second diode D2; the first unidirectional conduction unit 17 is the third diode D3; the first full-wave rectifier unit 111 is the first rectifier bridge DB1, and the second full-wave rectifier unit 112 is the second rectifier bridge DB2.

[0051] The first AC source 131 can come from the power grid, such as... Figure 5 In Grid-R1 and Grid-S1, the second AC source 132 can come from a generator, such as... Figure 5GEN-R and GEN-S, or the first AC source 131 and the second AC source 132, can both be derived from the power grid, such as from Grid-R1 and Grid-S1. When the amplitude and phase of the outputs of the first AC source 131 and the second AC source 132 are consistent, the charging speed of the bus capacitor can be accelerated, and the stress on the bus capacitors of the first full-wave rectifier unit 111, the second full-wave rectifier unit 112, and the DC bus 14 can be reduced.

[0052] Furthermore, the conduction direction of the first half-wave rectifier unit 121 is opposite to that of the second half-wave rectifier unit 122, that is, the voltage output by the first AC source 131 takes the positive half-cycle, and the voltage output by the second AC source 132 takes the negative half-cycle. In this way, for the bus capacitor, it is equivalent to receiving the voltage output after full-wave rectification, and the influence of peak current is almost eliminated, and the charging is more stable.

[0053] Example 5

[0054] This embodiment is a further optimization based on Embodiment 1, Embodiment 2, Embodiment 3, or Embodiment 4, such as... Figure 6 As shown, the photovoltaic inverter can be connected to a battery and can switch between grid-connected and off-grid operation. Power is required to start the device. If the inverter operates off-grid, it draws power from the battery. The battery's own voltage is only a few tens of volts. However, the energy storage photovoltaic inverter has numerous internal components, and starting it requires high power. If driven directly by the battery voltage, the required current would be large, causing significant damage to the battery and the internal components of the inverter. Therefore, the battery voltage needs to be boosted from tens of volts to around 200 volts, thus requiring less current. It is worth noting that because the DC bus 14 has a large number of bus capacitors, the boosted voltage is not high. Therefore, initially, the battery power supply will not charge the DC bus 14; otherwise, it would lead to undervoltage and unstable power supply to the internal components of the photovoltaic inverter. At this time, the battery power supply is used to start the internal components of the photovoltaic inverter, especially to start the driver board with its topology. When the driver board starts working, it can draw power from the battery, the grid, or the photovoltaic modules to charge the bus capacitor of DC bus 14 until the voltage of DC bus 14 rises to the required voltage. Afterward, the internal components of the photovoltaic inverter can be powered by DC bus 14. However, existing solutions all draw power separately, actively selecting the auxiliary power source through a chip. This requires additional circuitry, increasing costs and hindering cost reduction and space-saving improvements.

[0055] Therefore, as Figure 6As shown, this embodiment describes a power supply circuit for a photovoltaic inverter, including a first auxiliary power supply circuit 2, a second auxiliary power supply circuit 1, and a voltage conversion circuit 3. The second auxiliary power supply circuit 1 is the startup auxiliary power supply circuit of Embodiment 1, Embodiment 2, Embodiment 3, or Embodiment 4. The input terminal of the first auxiliary power supply circuit 2 receives the battery voltage, and the output terminal of the first auxiliary power supply circuit 2 is connected to the input terminal of the voltage conversion circuit 3 through the second unidirectional conduction unit 4. The first auxiliary power supply circuit 2 is used to convert the battery voltage into a second supply voltage. The second auxiliary power supply circuit 1 is used to output the first supply voltage to the DC bus 14. The DC bus 14 is connected to the input terminal of the voltage conversion circuit 3 through the third unidirectional conduction unit 5. When the second supply voltage is greater than the bus voltage of the DC bus 14, the second unidirectional conduction unit 4 is turned on and the third unidirectional conduction unit 5 is turned off. The voltage conversion circuit 3 converts the second supply voltage into a supply voltage for one or more devices and outputs it. When the bus voltage of the DC bus 14 is greater than the second supply voltage, the second unidirectional conduction unit 4 is turned off and the third unidirectional conduction unit 5 is turned on. The voltage conversion circuit 3 converts the bus voltage of the DC bus 14 into a supply voltage for one or more devices and outputs it to supply power to the internal components of the photovoltaic inverter.

[0056] The first auxiliary power circuit 2 boosts the battery voltage from tens of volts to approximately 200 volts, meaning the second supply voltage is approximately 200 volts. In this embodiment, the photovoltaic inverter is started collaboratively by the first auxiliary power circuit 2 and the startup auxiliary power circuit. Specifically, if the grid connection fails and the DC bus 14 has no voltage, the second unidirectional conduction unit 4 conducts, and the third unidirectional conduction unit 5 is cut off to prevent the second supply voltage from flowing back into the DC bus 14. At this time, the internal components of the photovoltaic inverter are powered by the battery. If the grid connection is successful, even if the photovoltaic inverter's drive board has not yet started, the voltage on the DC bus 14 will exceed the second supply voltage. In this case, the second unidirectional conduction unit 4 is cut off to prevent the DC bus 14 voltage from flowing back into the first auxiliary power circuit 2, and the third unidirectional conduction unit 5 is conducted. At this time, the internal components of the photovoltaic inverter are powered by the grid. Unlike the startup auxiliary power circuit, the first auxiliary power circuit 2 is always running and operating. If the DC bus 14 experiences an abnormality and the voltage abnormally drops below the second supply voltage, the second unidirectional conduction unit 4 conducts, and the third unidirectional conduction unit 5 is cut off. The photovoltaic inverter is continuously powered by the battery, ensuring its stable operation and enhancing the stability of the entire photovoltaic system.

[0057] Furthermore, such as Figure 6 and Figure 7As shown, the first auxiliary power supply circuit 2 includes a voltage detection circuit 21 and a first flyback circuit 22. The voltage detection circuit 21 outputs a feedback signal to the first flyback circuit 22 when the battery voltage is less than a first threshold. The input terminal of the first flyback circuit 22 is connected to the input terminal of the first auxiliary power supply circuit 2, and the output terminal of the first flyback circuit 22 is connected to the output terminal of the first auxiliary power supply circuit 2. The first flyback circuit 22 converts the battery voltage into a second supply voltage, and stops converting the battery voltage into the second supply voltage when a low-voltage signal is received. The voltage detection circuit 21 detects... Figure 7 The voltage of the VCCB in the first flyback circuit 22 is divided and compared with the voltage of the TL431. VCCB is the battery voltage after electromagnetic interference filtering, and TL431 is a controllable precision voltage regulator. If the voltage after VCCB division is less than the first threshold of 2.5V set by TL431, the COMP terminal of the flyback chip in the first flyback circuit 22 will receive a low-level feedback signal. The first flyback circuit 22 will then output a low-level pulse signal, thus preventing it from converting the battery voltage to the second supply voltage, thereby protecting the battery. Other methods, such as a comparator, can also be used for comparison. The principle of how the first flyback circuit 22 converts the battery voltage to the second supply voltage is existing technology and will not be elaborated in this embodiment.

[0058] Furthermore, such as Figure 8 As shown, the voltage conversion circuit 3 includes a transformer 31, a second switching transistor Q2, a pulse control circuit 32, a feedback circuit 33, and a voltage divider circuit 34.

[0059] The transformer 31 has a primary winding and multiple secondary windings. The first end of the primary winding is connected to the input end of the voltage conversion circuit 3, and the multiple secondary windings output the device supply voltage respectively. The first terminal of the second switching transistor Q2 is connected to the second end of the primary winding of the transformer 31.

[0060] The pulse signal output terminal of the pulse control circuit 32 is connected to the control electrode of the second switching transistor Q2, and the pulse control circuit 32 and the second electrode of the second switching transistor Q2 share a common ground. The pulse control circuit 32 is used to output a pulse signal and control the second switching transistor Q2 to turn on or off, so as to control the conversion of electrical energy received at the input terminal of the voltage conversion circuit 3 from the primary winding to the secondary winding of the transformer 31. The input terminal of the feedback circuit 33 receives the supply voltage of a device, such as... Figure 8 The POWER_H+12V in the circuit is connected to the feedback signal terminal of the pulse control circuit 32 and outputs a feedback signal. The pulse control circuit 32 adjusts the duty cycle of the pulse signal according to the feedback signal.

[0061] Voltage divider circuit 34 is used to divide the voltage when pulse control circuit 32 is started, so as to provide a start-up voltage for pulse control circuit 32. Voltage divider circuit 34 includes a first voltage divider branch 341 and a second voltage divider branch 342. The first end of the first voltage divider branch 341 is connected to the primary winding of transformer 31, and the second end of the first voltage divider branch 341 is connected to the start-up voltage power supply terminal of pulse control circuit 32. The first voltage divider branch 341 includes at least two first voltage divider units connected in series, and each first voltage divider unit includes at least two resistors connected in parallel. The first end of the second voltage divider branch 342 is connected to the start-up voltage power supply terminal of pulse control circuit 32, and the second end of the second voltage divider branch 342 is grounded. The second voltage divider branch 342 includes at least two second voltage divider units connected in series, and each second voltage divider unit includes at least two resistors connected in parallel.

[0062] The control chip of the pulse control circuit 32 is ICE3BS03LJG. The internal startup unit of the chip is used to power the chip's VCC. Therefore, the chip's startup voltage power supply terminal HV needs to receive a large voltage for high-voltage startup. The voltage divider circuit 34 is used to divide the voltage when the pulse control circuit 32 starts up to provide the control chip with a suitable startup voltage. The resistor network of the first voltage divider branch 341 and the second voltage divider branch 342 of the voltage divider circuit 34 is used to facilitate heat dissipation.

[0063] Example 6

[0064] A photovoltaic inverter according to an embodiment of this application includes a startup auxiliary power circuit or a power supply circuit of any of the foregoing embodiments, wherein the startup auxiliary power circuit or power supply circuit is used to supply power to the photovoltaic inverter.

[0065] In addition, in the accompanying drawings of this application, lines crossing each other with a dot indicate that these lines are connected together. Lines without a dot indicate that they are not connected. Refer to the circuit schematic design.

[0066] The Chinese and English labels on the circuit connection lines, such as positive bus, negative bus, VCCB, POWER_H+12V, etc., represent the input and output points of the signals. The appearance of the same Chinese and English labels in different diagrams indicates that they are connected. This is the common practice in circuit schematics, so this application will not elaborate further.

[0067] The division of units in the embodiments of this application is merely a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0068] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0069] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0070] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the solutions disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A startup auxiliary power circuit for a photovoltaic inverter, characterized in that, include: Half-wave rectifier unit (12), full-wave rectifier unit (11) and first unidirectional conduction unit (17); The AC input terminal of the full-wave rectifier unit (11) is connected to the AC source (13) of the start-up auxiliary power supply circuit through the half-wave rectifier unit (12); the DC output terminal of the full-wave rectifier unit (11) is connected to the DC bus (14) of the photovoltaic inverter through the first unidirectional conduction unit (17); the DC output terminal of the full-wave rectifier unit (11) outputs a first supply voltage to the DC bus (14) and the voltage of the DC bus (14) is used as the start-up voltage of the photovoltaic inverter.

2. The auxiliary power supply circuit for starting a photovoltaic inverter according to claim 1, characterized in that, It also includes a switching unit (15); the DC output terminal of the full-wave rectifier unit (11) includes a first DC output terminal and a second DC output terminal; The first DC output terminal of the full-wave rectifier unit (11) is connected to the first terminal of the switch unit (15) through the first unidirectional conduction unit (17), the second terminal of the switch unit (15) is connected to the positive bus of the DC bus (14), the third terminal of the switch unit (15) is connected to the second DC output terminal of the full-wave rectifier unit (11), and the fourth terminal of the switch unit (15) is connected to the negative bus of the DC bus (14).

3. The auxiliary power supply circuit for starting a photovoltaic inverter according to claim 2, characterized in that, The switching unit (15) includes a multi-pole relay (18) and a relay control module (19). The multi-pole relay (18) includes a driver (183), a first switch (184), and a second switch (185). The first end of the first switch (184) is connected to the first end of the switch unit (15), and the second end of the first switch (184) is connected to the second end of the switch unit (15). The first end of the second switch (185) is connected to the third end of the switch unit (15), and the second end of the second switch (185) is connected to the fourth end of the switch unit (15). The relay control module (19) is connected to the first end of the drive unit (183), and the second end of the drive unit (183) is connected to the third power supply voltage. The relay control module (19) controls the on or off of the first switch unit (184) and the second switch unit (185).

4. The auxiliary power supply circuit for starting a photovoltaic inverter according to claim 3, characterized in that, The relay control module (19) includes: At least one fourth diode (D4), the anode of which is connected to a first end of the driving member (183), and the cathode of which is connected to a second end of the driving member (183); The first resistor (R1) receives the relay control signal at its first terminal; The second resistor (R2) has its first end connected to the first end of the first resistor (R1), and its second end connected to the negative busbar. The first switch (Q1) has its control electrode connected to the second terminal of the first resistor (R1), its first electrode connected to the first terminal of the driving device (183), and its second electrode connected to the negative bus. The control electrode of the first switch (Q1) controls the conduction or de-conduction of the first electrode and the second electrode of the first switch (Q1) according to the relay control signal.

5. The auxiliary power supply circuit for starting a photovoltaic inverter according to claim 4, characterized in that, The number of multi-pole relays (18) is two, which are defined as the first multi-pole relay (181) and the second multi-pole relay (182). The first switch (184) of the first multi-pole relay (181) is connected to the first end of the switch unit (15), one end of the first switch (184) of the second multi-pole relay (182) is connected to the first switch (184) of the first multi-pole relay (181), and the other end of the first switch (184) of the second multi-pole relay (182) is connected to the second end of the switch unit (15). The second switch (185) of the first multi-pole relay (181) is connected to the third end of the switch unit (15), one end of the second switch (185) of the second multi-pole relay (182) is connected to the second switch (185) of the first multi-pole relay (181), and the other end of the second switch (185) of the second multi-pole relay (182) is connected to the fourth end of the switch unit (15). The driving element (183) of the first multi-pole relay (181) and the driving element (183) of the second multi-pole relay (182) are both connected to the first pole of the first switching transistor (Q1).

6. The auxiliary power supply circuit for starting a photovoltaic inverter according to claim 5, characterized in that, It also includes a surge protection unit (16); The first DC output terminal of the full-wave rectifier unit (11) is connected to the positive bus of the DC bus (14) through the first unidirectional conduction unit (17); the second DC output terminal of the full-wave rectifier unit (11) is connected to the negative bus of the DC bus (14); the first end of the surge protection unit (16) is connected to the first DC output terminal of the full-wave rectifier unit (11), and the second end of the surge protection unit (16) is connected to the second DC output terminal of the full-wave rectifier unit (11); The surge protection unit (16) includes a third resistor (R3), a fourth resistor (R4), a first capacitor (C1), and a second capacitor (C2). The first end of the third resistor (R3) is connected to the first DC output terminal of the full-wave rectifier unit (11), the second end of the third resistor (R3) is connected to the first end of the fourth resistor (R4), and the second end of the fourth resistor (R4) is connected to the second DC output terminal of the full-wave rectifier unit (11). The first terminal of the first capacitor (C1) is connected to the first DC output terminal of the full-wave rectifier unit (11), the second terminal of the first capacitor (C1) is connected to the first terminal of the second capacitor (C2) and the second terminal of the first resistor (R1), and the second terminal of the second capacitor (C2) is connected to the second DC output terminal. The first DC output terminal of the full-wave rectifier unit (11) is connected to the first switch (184) through the first unidirectional conduction unit (17). The first unidirectional conduction unit (17) is a fourth diode (D4). The anode of the fourth diode (D4) is connected to the first terminal of the first switch (184), and the cathode of the fourth diode (D4) is connected to the first DC output terminal of the full-wave rectifier unit (11). The third resistor (R3) and the fourth resistor (R4) are both varistors.

7. The auxiliary power supply circuit for starting a photovoltaic inverter according to any one of claims 2-6, characterized in that, The number of full-wave rectifier units (11) is two, which are defined as the first full-wave rectifier unit (111) and the second full-wave rectifier unit (112); the number of half-wave rectifier units (12) is two, which are defined as the first half-wave rectifier unit (121) and the second half-wave rectifier unit (122); the number of AC sources (13) for starting the auxiliary power supply circuit is two, which are defined as the first AC source (131) and the second AC source (132). The AC input terminal of the first full-wave rectifier unit (111) is connected to the first AC source (131) of the start-up auxiliary power source circuit through the first half-wave rectifier unit (121). The AC input terminal of the second full-wave rectifier unit (112) is connected to the second AC source (132) of the starting auxiliary source circuit through the second half-wave rectifier unit (122). The first DC output terminal of the first full-wave rectifier unit (111) is connected to the first DC output terminal of the second full-wave rectifier unit (112); the second DC output terminal of the first full-wave rectifier unit (111) is connected to the second DC output terminal of the second full-wave rectifier unit (112).

8. The auxiliary power supply circuit for starting a photovoltaic inverter according to claim 7, characterized in that, The conduction direction of the first half-wave rectifier unit (121) is opposite to that of the second half-wave rectifier unit (122); The first half-wave rectifier unit (121) is a first diode (D1), and the second half-wave rectifier unit (122) is a second diode (D2). The first unidirectional conduction unit (17) is a third diode (D3).

9. A power supply circuit for a photovoltaic inverter, characterized in that, include: The circuit consists of a first auxiliary power source circuit (2), a second auxiliary power source circuit (1), and a voltage conversion circuit (3), wherein the second auxiliary power source circuit (1) is the starting auxiliary power source circuit as described in any one of claims 1-8; The input terminal of the first auxiliary power supply circuit (2) receives the battery voltage, and the output terminal of the first auxiliary power supply circuit (2) is connected to the input terminal of the voltage conversion circuit (3) through the second unidirectional conduction unit (4). The first auxiliary power supply circuit (2) is used to convert the battery voltage into a second power supply voltage. The second auxiliary power supply circuit (1) is used to output the first power supply voltage to the DC bus (14), and the DC bus (14) is connected to the input terminal of the voltage conversion circuit (3) through the third unidirectional conduction unit (5); When the second supply voltage is greater than the bus voltage of the DC bus (14), the second unidirectional conduction unit (4) is turned on, the third unidirectional conduction unit (5) is turned off, and the voltage conversion circuit (3) converts the second supply voltage into the supply voltage of one or more devices and outputs it. When the bus voltage of the DC bus (14) is greater than the second supply voltage, the second unidirectional conduction unit (4) is turned off, the third unidirectional conduction unit (5) is turned on, and the voltage conversion circuit (3) converts the bus voltage of the DC bus (14) into the supply voltage of one or more devices and outputs it.

10. The power supply circuit according to claim 9, characterized in that, The first auxiliary power circuit (2) includes a voltage detection circuit (21) and a first flyback circuit (22); The voltage detection circuit (21) is used to output a feedback signal to the first flyback circuit (22) when the battery voltage is less than the first threshold. The input terminal of the first flyback circuit (22) is connected to the input terminal of the first auxiliary power supply circuit (2), the output terminal of the first flyback circuit (22) is connected to the output terminal of the first auxiliary power supply circuit (2), the first flyback circuit (22) converts the battery voltage into the second power supply voltage, and when a low voltage signal is received, the first flyback circuit (22) stops converting the battery voltage into the second power supply voltage.

11. The power supply circuit according to claim 9, characterized in that, The voltage conversion circuit (3) includes: The transformer (31) has a primary winding and multiple secondary windings. The first end of the primary winding is connected to the input end of the voltage conversion circuit (3), and the multiple secondary windings output the device power supply voltage respectively. The first terminal of the second switch (Q2) is connected to the second terminal of the primary winding of the transformer (31); The pulse control circuit (32) has its pulse signal output terminal connected to the control electrode of the second switching transistor (Q2). The pulse control circuit (32) and the second electrode of the second switching transistor (Q2) share a common ground. The pulse control circuit (32) is used to output a pulse signal and to control the second switching transistor (Q2) to be turned on or off, so as to control the electrical energy received at the input terminal of the voltage conversion circuit (3) to be converted from the primary winding to the secondary winding of the transformer (31). The feedback circuit (33) receives the power supply voltage of the device at its input terminal and its output terminal is connected to the feedback signal terminal of the pulse control circuit (32) and outputs a feedback signal. The pulse control circuit (32) adjusts the duty cycle of the pulse signal according to the feedback signal. Voltage divider circuit (34) is used to divide the voltage when the pulse control circuit (32) is started, so as to provide a start-up voltage for the pulse control circuit (32); The voltage divider circuit (34) includes a first voltage divider branch (341) and a second voltage divider branch (342). The first end of the first voltage divider branch (341) is connected to the primary winding of the transformer (31), and the second end of the first voltage divider branch (341) is connected to the start-up voltage power supply terminal of the pulse control circuit (32); the first voltage divider branch (341) includes at least two first voltage divider units connected in series, and each first voltage divider unit includes at least two resistors connected in parallel; The first end of the second voltage divider branch (342) is connected to the start-up voltage power supply terminal of the pulse control circuit (32), and the second end of the second voltage divider branch (342) is grounded; the second voltage divider branch (342) includes at least two second voltage divider units connected in series, and each second voltage divider unit includes at least two resistors connected in parallel.

12. A photovoltaic inverter, characterized in that, It includes the startup auxiliary power supply circuit as described in any one of claims 1-8, or the power supply circuit as described in any one of claims 9-11.

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