Photovoltaic inverter auxiliary power supply circuitry

Abstract

The application belongs to the technical field of photovoltaic inverters, and discloses a photovoltaic inverter auxiliary power supply circuit system, which comprises a BAT auxiliary power supply circuit, a high-voltage auxiliary power supply circuit, a PV micro auxiliary power supply circuit and a switching circuit, the PV micro auxiliary power supply circuit is electrically connected and controls the switching circuit, the switching circuit is electrically connected with the high-voltage auxiliary power supply circuit, the high-voltage auxiliary power supply circuit is electrically connected with the BAT auxiliary power supply circuit, the high-voltage auxiliary power supply circuit cooperates with the switching circuit to output photovoltaic panel voltage or AC grid voltage after voltage reduction, and activates and starts the BAT auxiliary power supply circuit, the PV micro auxiliary power supply is designed with extremely small power capacity, and the high-voltage auxiliary power supply circuit is designed with small power capacity; the high-voltage auxiliary power supply of the photovoltaic panel voltage and the AC grid voltage is combined into one through the switching circuit multiplexing, the circuit is more simplified, the total power capacity of the auxiliary power supply is reduced, and the specifications of components and elements, the circuit volume, the weight and the like are designed to be smaller.

Description

Technical Field

[0001] This invention belongs to the technical field of photovoltaic inverters, and more specifically, relates to an auxiliary power supply circuit system for photovoltaic inverters. Background Technology

[0002] High-voltage photovoltaic (PV) input voltage (e.g., 100V-400Vdc) is the mainstream input parameter configuration requirement for small PV inverters currently on the market. The main circuit structure involves the PV input voltage being boosted by a Boost circuit to deliver solar energy to the inverter bus. The inverter then uses an H-bridge or other inverter circuits to convert the DC bus voltage into AC output voltage. When the AC grid voltage is input to the inverter, it can switch to bypass mode to directly deliver grid energy to the load. When the inverter and battery pack are in sleep mode or shut down due to low battery, any power supply to either the PV or grid input ports should be able to activate the inverter and battery pack to automatically enter charging mode to store energy or convert energy for delivery to the load.

[0003] To achieve this activation function, the existing general solution is as follows: design three DC-DC isolation circuits. One of them is a PV auxiliary power supply (usually called a PV auxiliary power source) to convert the energy input from the PV into an output DC voltage (such as 24Vdc) to supply the BAT auxiliary power supply circuit as input (i.e., the auxiliary power supply at the battery end, an isolated DC-DC power supply circuit, used to isolate and convert the battery voltage or other DC input voltage to output voltages such as 12V, 5V, 3.3V, etc. to supply the various functional circuits of the inverter to achieve the purpose of activating the system). The other is an AC auxiliary power supply (usually called an AC auxiliary power source) to convert the energy at the AC input port. Its purpose and effect are the same as those of the PV auxiliary power supply.

[0004] However, this solution has the following problems: First, the PV auxiliary power supply and AC auxiliary power supply in this solution share common circuit characteristics, both being high-voltage isolation converters that output low voltage. Their input ranges are similar, their output voltages are consistent, and their hardware component selection and parameter design are basically the same, resulting in design redundancy, occupying circuit board space, and wasting material costs. Second, in the existing solution, the three DC-DC power supply circuits are arranged in a "2+1" pyramid-shaped stacked structure. Each auxiliary power supply needs to be designed with a large power capacity to achieve full-power load (i.e., the output power of both the PV and AC auxiliary power supplies needs to meet the load of the BAT auxiliary power supply circuit. For example, if the BAT auxiliary power supply circuit requires a 50W power output design, then both the PV and AC auxiliary power supplies need to be designed and selected according to a 60W output power, requiring a total auxiliary power supply capacity of 170W). This results in high component costs, significant reactive power losses, and wasted resources and energy.

[0005] Therefore, the present invention provides an auxiliary power supply circuit system for a photovoltaic inverter. Summary of the Invention

[0006] In view of the above-mentioned defects and shortcomings of the existing technology, there is a need for a circuit design scheme that is efficient, simple and cost-effective. The purpose of this invention is to provide an auxiliary power supply circuit system for a photovoltaic inverter.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A photovoltaic inverter auxiliary power supply circuit system includes a BAT auxiliary power supply circuit, a high-voltage auxiliary power supply circuit, a PV micro auxiliary power supply circuit, and a switching circuit. The PV micro auxiliary power supply circuit is electrically connected to and controls the switching circuit. The switching circuit is electrically connected to the high-voltage auxiliary power supply circuit. The high-voltage auxiliary power supply circuit is electrically connected to the BAT auxiliary power supply circuit.

[0009] It also includes a BAT port, a PV port, an AC input port, and an AC output port. The BAT auxiliary power supply circuit is electrically connected to the battery through the BAT port. The PV micro auxiliary power supply circuit is connected to the photovoltaic panel voltage Vpv through the PV port. The switching circuit is also connected to the photovoltaic panel voltage Vpv through the PV port. The switching circuit is connected to the AC grid voltage Vac through the AC input port.

[0010] The high-voltage auxiliary power supply circuit, in coordination with the switching circuit, steps down the photovoltaic panel voltage Vpv or the AC grid voltage Vac to output Vdc, and activates the BAT auxiliary power supply circuit. The PV micro auxiliary power supply circuit is designed for extremely small power capacity, and the high-voltage auxiliary power supply circuit is designed for small power capacity. The switching circuit prioritizes the photovoltaic input path when the photovoltaic panel voltage Vpv is present, and automatically switches to the AC grid input path when the photovoltaic panel voltage is absent.

[0011] As a further preferred technical solution of the present invention, the PV micro auxiliary power supply circuit is provided with a control chip U1. The control chip U1 has a built-in MOS transistor and a feedback loop. The control chip U1 has at least 8 pins. Pins 5 to 8 of the control chip U1 are the drains of the built-in MOS transistor. Pins 1 to 2 of the control chip U1 are grounded to GND. Pin 3 of the control chip U1 is a floating NC pin. Pin 4 of the control chip U1 is the VDD operating voltage.

[0012] As a further preferred technical solution of the present invention, the PV port is provided with a wiring terminal PV+ and a wiring terminal PV-;

[0013] Pins 5-8 of the control chip U1 are connected to terminal PV+. Pins 5-8 of the control chip U1 are also electrically connected to capacitor CE2. Pin 4 of the control chip U1 is electrically connected to diode D1. Pin 4 of the control chip U1 is electrically connected to capacitor C1. Pins 1-2 of the control chip U1 are electrically connected. Pins 1-2 of the control chip U1 are electrically connected to inductor L1. Pins 1-2 of the control chip U1 are also electrically connected to diode D2. Capacitor C1 is also electrically connected to diode D2 and inductor L1. Diode D1 is also electrically connected to inductor L1 and capacitor CE1. Capacitor CE1, diode D2, and capacitor CE2 are electrically connected and connected to terminal PV-.

[0014] The control chip U1, together with its surrounding electronic components, forms a high-voltage BUCK circuit that converts the PV voltage of the photovoltaic panel and outputs the VCC1 voltage to the switching circuit.

[0015] As a further preferred technical solution of the present invention, the switching circuit is provided with a relay RY1, the relay RY1 has at least 8 pins, a coil is provided between pins 1 and 8 of the relay RY1, pin 1 of the relay RY1 is electrically connected to the terminal D of the MOSFET Q1, pin 8 of the relay RY1 is electrically connected to a resistor R1, the resistor R1 is electrically connected to a resistor R2, one end of the resistor R2 is electrically connected to the terminal S of the MOSFET Q1, the other end of the resistor R2 is electrically connected to the terminal G of the MOSFET Q1, the resistor R2 is connected in parallel with a capacitor C2, and the resistor R1 is connected to the VCC1 voltage.

[0016] As a further preferred technical solution of the present invention, the AC input port is provided with terminal block AC-L and terminal block AC-N;

[0017] Pins 3 and 6 of relay RY1 are common terminals of the relay. Pin 3 is electrically connected to terminal V1-, and pin 6 is electrically connected to terminal V1+. A capacitor EC1 is electrically connected between terminal V1- and terminal V1+. Pin 7 of relay RY1 is connected to terminal PV+, and pin 2 of relay RY1 is connected to terminal PV-. Pins 4 and 5 of relay RY1 are both electrically connected to rectifier bridge REC1. Rectifier bridge REC1 is electrically connected to terminal AC-N. Rectifier bridge REC1 is also electrically connected to fuse F1. Fuse F1 is electrically connected to terminal AC-L.

[0018] The switching circuit converts the AC mains voltage Vac, which is connected to the AC-N terminal, into a high-voltage DC voltage Vrec after being rectified by the rectifier bridge REC1. Vrec = Vac. The switching circuit outputs a high-voltage DC voltage V1, which is Vpv or Vrec, to the high-voltage auxiliary power supply circuit through the V1- and V1+ terminals.

[0019] As a further preferred technical solution of the present invention, the high-voltage auxiliary power supply circuit is a flyback isolated DC-DC power supply circuit. The high-voltage auxiliary power supply circuit is used to isolate and convert the high-voltage DC voltage V1 into a low-voltage DC voltage Vdc, and supply the DC voltage Vdc to the BAT auxiliary power supply circuit. The high-voltage auxiliary power supply circuit is composed of a control chip, terminals, resistors, MOSFETs, transformers, Zener diodes, transistors, capacitors, and diodes electrically connected together.

[0020] As a further preferred technical solution of the present invention, the high-voltage auxiliary power supply circuit is provided with a control chip U2. The control chip U2 has several sets of pins. The control chip U2 is electrically connected to the terminal V1- through the pins. The control chip U2 is electrically connected to the resistor R7 through the pins. The control chip U2 is also electrically connected to the MOSFET Q3 through the pins. Specifically, the control chip U2 is electrically connected to the terminal G of the MOSFET Q3 through the pins. One pin of the control chip U2 is the VDD working voltage. The resistor R7 is also electrically connected to the terminal S of the MOSFET Q3. The terminal of the MOSFET Q3 is electrically connected to the transformer TX1. Specifically, the terminal of the MOSFET Q3 is electrically connected to the winding taps 5 and 6 of the transformer TX1.

[0021] The winding taps 5 and 6 of the transformer TX1 are also electrically connected to the terminal V1+. The terminal V1+ is electrically connected to resistors R4 and R5 respectively. Resistors R4, R3, R6, Zener diodes ZD1 and ZD2 are connected in series. Resistor R5 is electrically connected to transistor Q2. Zener diodes ZD1 and ZD2 are electrically connected to transistor Q2. Transistor Q2 is also electrically connected to capacitor C3. Zener diode ZD2 is also electrically connected to capacitor C3. One end of capacitor C3 is electrically connected to winding taps 8 and 10 of the transformer TX1. The other end of capacitor C3 is electrically connected to diode D5. Diode D5 is also electrically connected to winding taps 8 and 10 of the transformer TX1. Transistor Q2 and capacitor C3 are electrically connected to pin VDD. Zener diode ZD2 and capacitor C3 are electrically connected to terminal V1-.

[0022] As a further preferred technical solution of the present invention, the BAT port is provided with a wiring terminal BAT+ and a wiring terminal BAT-, and the voltage of the BAT port is Vbat;

[0023] One end of the winding taps 1 and 3 of the transformer TX1 is electrically connected to diode D3, and the other end of the winding taps 1 and 3 of the transformer TX1 is electrically connected to capacitor EC2. Diode D3 is electrically connected to the other end of capacitor EC2. One end of capacitor EC2 is electrically connected to diode D4. The other end of capacitor EC2 is electrically connected to the BAT auxiliary power supply circuit. The other end of diode D4 is electrically connected to the BAT auxiliary power supply circuit. Vbat is connected between diode D4 and the BAT auxiliary power supply circuit. The capacitor EC2 is electrically connected to terminal BAT- between the BAT auxiliary power supply circuit and the terminal BAT-.

[0024] The high-voltage DC power V1 is input to the high-voltage auxiliary power supply circuit through terminals V1+ and V1-, and is transmitted to its winding taps 1 and 3 through transformer TX1 for isolation. It is then rectified and filtered by diode D3 and EC2 to output Vdc.

[0025] As a further preferred technical solution of the present invention, the BAT auxiliary power supply circuit is electrically connected to the inverter main power circuit. The BAT auxiliary power supply circuit is a flyback isolated DC-DC power supply circuit. The BAT auxiliary power supply circuit is used to isolate and convert the BAT port voltage Vbat or DC voltage Vdc to output voltages such as 12V, 5V, and 3.3V to supply the inverter main power circuit. The DC voltage Vdc is less than or equal to the minimum value of the battery port voltage Vbat.

[0026] As a further preferred technical solution of the present invention, the AC output port is provided with terminal L and terminal N;

[0027] The inverter's main power circuit includes a first DC / DC circuit, which is electrically connected to terminals BAT+ and BAT- of the BAT port. The first DC / DC circuit is also electrically connected to a second DC / DC circuit via an isolation transformer. The second DC / DC circuit is electrically connected to the DC / AC circuit of the inverter's main power circuit. A third DC / DC circuit is electrically connected between the second DC / DC circuit and the DC / AC circuit. This third DC / DC circuit is electrically connected to terminals AC-L and AC-N of the AC input port to connect to the AC grid voltage Vac. It is also electrically connected to terminals L and N of the AC output port. The third DC / DC circuit is electrically connected to terminals PV+ and PV- of the PV input port to connect to the photovoltaic panel voltage Vpv.

[0028] An automatic switching circuit is provided between the DC / AC circuit and the AC input port, and an automatic switching circuit is also provided between the DC / AC circuit and the AC output port.

[0029] As described above, the photovoltaic inverter auxiliary power supply circuit system provided by the present invention has the following beneficial effects:

[0030] 1. The present invention utilizes the above-mentioned photovoltaic inverter auxiliary power supply circuit system. Compared with the prior art, by using the multiplexing setting of the switching circuit, the high-voltage to low-voltage auxiliary power supply of the photovoltaic panel voltage Vpv and the AC grid Vac is combined into one. The circuit is more streamlined, the total power capacity of the auxiliary power supply is greatly reduced, some components can be selected with smaller specifications, and the circuit volume and weight can be designed to be smaller, resulting in more obvious cost advantages and strong product competitiveness.

[0031] 2. Compared with the prior art, the present invention utilizes the above-mentioned photovoltaic inverter auxiliary power supply circuit system. Through the coordinated operation of the PV micro auxiliary power supply circuit, the switching circuit, the high-voltage auxiliary power supply circuit, the BAT auxiliary power supply circuit, and the automatic switching circuit of the inverter main power circuit, the photovoltaic inverter auxiliary power supply circuit system prioritizes the consumption of clean solar energy, followed by grid energy, and finally battery energy. This is environmentally friendly and improves battery life.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the auxiliary power supply circuit system for a photovoltaic inverter according to the present invention.

[0035] Figure 2 The circuit structure diagram of the PV micro auxiliary power supply circuit and switching circuit of the photovoltaic inverter auxiliary power supply circuit system is provided in this invention application.

[0036] Figure 3 This invention relates to a circuit diagram of a high-voltage auxiliary power supply circuit for a photovoltaic inverter auxiliary power supply circuit system.

[0037] Figure 4 This is a partial circuit diagram of the main power circuit of a photovoltaic inverter auxiliary power supply circuit system, which is the subject of this invention. Detailed Implementation

[0038] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0039] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention. Specific structures can be described with reference to the accompanying drawings of the patent application.

[0040] This invention provides an auxiliary power supply circuit system for a photovoltaic inverter. Please refer to [link / reference]. Figures 1 to 4 As shown, it includes a BAT auxiliary power supply circuit, a high-voltage auxiliary power supply circuit, a PV micro auxiliary power supply circuit, and a switching circuit. The PV micro auxiliary power supply circuit is electrically connected to and controls the switching circuit. The switching circuit is electrically connected to the high-voltage auxiliary power supply circuit. The high-voltage auxiliary power supply circuit is electrically connected to the BAT auxiliary power supply circuit.

[0041] It also includes a BAT port, a PV port, an AC input port, and an AC output port. The BAT auxiliary power supply circuit is electrically connected to the battery through the BAT port. The PV micro auxiliary power supply circuit is connected to the photovoltaic panel voltage Vpv through the PV port. The switching circuit is also connected to the photovoltaic panel voltage Vpv through the PV port. The switching circuit is connected to the AC grid voltage Vac through the AC input port.

[0042] The high-voltage auxiliary power supply circuit, in coordination with the switching circuit, reduces the photovoltaic panel voltage Vpv or the AC grid voltage Vac to output Vdc, and activates the BAT auxiliary power supply circuit.

[0043] The PV micro-auxiliary power supply circuit is designed with extremely small power capacity.

[0044] The high-voltage auxiliary power supply circuit is designed with low power capacity.

[0045] The BAT auxiliary power supply circuit is designed for full-power load operation.

[0046] Specifically, the specific circuit structure of the PV micro-auxiliary power supply circuit is shown below, in conjunction with... Figure 2 As shown, the PV micro auxiliary power supply circuit is equipped with a control chip U1. The control chip U1 has a built-in MOS transistor and a feedback loop. The control chip U1 has at least 8 pins. Pins 5 to 8 of the control chip U1 are the drains of the built-in MOS transistor. Pins 1 to 2 of the control chip U1 are grounded (GND). Pin 3 of the control chip U1 is a floating NC pin. Pin 4 of the control chip U1 is the VDD operating voltage.

[0047] The PV port is equipped with terminals PV+ and PV-. Pins 5-8 of the control chip U1 are connected to terminal PV+. Pins 5-8 of the control chip U1 are also electrically connected to capacitor CE2. Pin 4 of the control chip U1 is electrically connected to diode D1. Pin 4 of the control chip U1 is electrically connected to capacitor C1. Pins 1-2 of the control chip U1 are electrically connected. Pins 1-2 of the control chip U1 are electrically connected to inductor L1. Pins 1-2 of the control chip U1 are also electrically connected to diode D2. Capacitor C1 is also electrically connected to diode D2 and inductor L1. Diode D1 is also electrically connected to inductor L1 and capacitor CE1. Capacitor CE1, diode D2, and capacitor CE2 are electrically connected and connected to terminal PV-. The control chip U1, together with its surrounding electronic components, forms a high-voltage BUCK circuit to convert the PV voltage of the photovoltaic panel and output voltage VCC1, where VCC1 = 12V, to the switching circuit.

[0048] It should be noted that in this embodiment, the control chip U1 is the On-bright OB2235RASP chip, the capacitor CE2 is the PV input capacitor, the diode D2 is the freewheeling diode of the BUCK circuit, the inductor L1 is the energy storage inductor of the BUCK circuit, the capacitor C E1 is the filter capacitor for the micro-auxiliary power supply output voltage VCC1, and the diode D1 and capacitor C1 form the bootstrap power supply circuit and the output voltage detection feedback circuit. It can be seen that the PV micro-auxiliary power supply circuit has a simple circuit structure, requires a very small power capacity design, has small device size, and has obvious cost advantages.

[0049] Specifically, the specific circuit structure of the switching circuit is shown below, in conjunction with... Figure 2As shown, the switching circuit includes a relay RY1 with at least 8 pins. A coil is located between pins 1 and 8 of the relay RY1. Pin 1 of the relay RY1 is electrically connected to terminal D of MOSFET Q1. Pin 8 of the relay RY1 is electrically connected to resistor R1. Resistor R1 is electrically connected to resistor R2. One end of resistor R2 is electrically connected to terminal S of MOSFET Q1, and the other end of resistor R2 is electrically connected to terminal G of MOSFET Q1. Resistor R2 is connected in parallel with capacitor C2, and resistor R1 is connected to voltage VCC1.

[0050] The AC input port is provided with terminals AC-L and AC-N; pins 3 and 6 of the relay RY1 are common terminals of the relay, pin 3 is electrically connected to terminal V1-, pin 6 is electrically connected to terminal V1+, a capacitor EC1 is electrically connected between terminal V1- and terminal V1+, pin 7 of the relay RY1 is connected to terminal PV+, pin 2 of the relay RY1 is connected to terminal PV-, pins 4 and 5 of the relay RY1 are both electrically connected to rectifier bridge REC1, rectifier bridge REC1 is electrically connected to terminal AC-N, rectifier bridge REC1 is also electrically connected to fuse F1, and fuse F1 is electrically connected to terminal AC-L;

[0051] The switching circuit converts the AC mains voltage Vac, which is connected to terminal AC-N, into a high-voltage DC voltage Vrec after rectification by rectifier bridge REC1. Vrec = The switching circuit outputs high-voltage DC power V1 to the high-voltage auxiliary power supply circuit through terminals V1- and V1+, where V1 = Vpv or Vrec.

[0052] It should be noted that when the photovoltaic inverter auxiliary power supply circuit system has PV voltage alone or PV and AC voltages exist simultaneously, the switching circuit will prioritize connecting the PV voltage to the common terminal to supply power to the high-voltage auxiliary power supply circuit, thereby delivering clean energy to the inverter's auxiliary power consumption.

[0053] When PV is present, the non-isolated BUCK step-down circuit outputs VCC1=12V. Due to the presence of VCC1, MOSFET Q1 is turned on, and the VCC1 voltage is applied to the coil of relay RY1, causing the common terminals Pin3 and Pin6 of the relay to be attracted and connected to Pin2 and Pin7 respectively, so that the PV voltage is connected to V1. The common terminal V1 is connected to the filter capacitor EC1, so that the energy of the subsequent high-voltage auxiliary power supply circuit is taken from PV solar energy.

[0054] When either AC voltage or PV voltage drops, U1 is not working, VCC1 has no voltage, MOSFET Q1 is not conducting, and relay RY1 is not working and is in a naturally open state. The common terminals Pin3 and Pin6 are connected to Pin4 and Pin5 respectively. Since the relays in the switching circuit are not in the energized state, the common terminal of the relay is usually connected to Vrec after the AC mains voltage is rectified. The high-voltage auxiliary power supply circuit is activated and extracts energy from Vrec to convert and output Vdc, so that the energy of the subsequent high-voltage auxiliary power supply circuit is taken from the AC mains.

[0055] Therefore, the power required to drive the relay to engage in the switching circuit is relatively small (only one small relay RY1 needs to be driven to close, for example, closing the relay requires 3W of power). As a result, the power capacity of the PV micro auxiliary power supply circuit is very small, and the corresponding device specifications and size are extremely small. Moreover, non-isolated circuits can be used, which greatly reduces the design cost.

[0056] The high-voltage auxiliary power supply circuit is a flyback isolated DC-DC power supply circuit. The high-voltage auxiliary power supply circuit is used to isolate and convert the high-voltage DC voltage V1 into a low-voltage DC voltage Vdc, and supply the DC voltage Vdc to the BAT auxiliary power supply circuit. The high-voltage auxiliary power supply circuit is composed of a control chip, terminals, resistors, MOSFETs, transformers, Zener diodes, transistors, capacitors, and diodes electrically connected together.

[0057] Specifically, the specific circuit structure of the high-voltage auxiliary power supply circuit is shown below, in conjunction with... Figure 3 As shown, the high-voltage auxiliary power supply circuit is equipped with a control chip U2. The control chip U2 has several sets of pins. The control chip U2 is electrically connected to the terminal V1- through the pins. The control chip U2 is electrically connected to the resistor R7 through the pins. The control chip U2 is also electrically connected to the MOSFET Q3 through the pins. Specifically, the control chip U2 is electrically connected to the terminal G of the MOSFET Q3 through the pins. One pin of the control chip U2 is the VDD working voltage. The resistor R7 is also electrically connected to the terminal S of the MOSFET Q3. The terminal of the MOSFET Q3 is electrically connected to the transformer TX1. Specifically, the terminal of the MOSFET Q3 is electrically connected to the winding taps 5 and 6 of the transformer TX1.

[0058] The winding taps 5 and 6 of the transformer TX1 are also electrically connected to the terminal V1+. The terminal V1+ is electrically connected to resistors R4 and R5 respectively. Resistors R4, R3, R6, Zener diodes ZD1 and ZD2 are connected in series. Resistor R5 is electrically connected to transistor Q2. Zener diodes ZD1 and ZD2 are electrically connected to transistor Q2. Transistor Q2 is also electrically connected to capacitor C3. Zener diode ZD2 is also electrically connected to capacitor C3. One end of capacitor C3 is electrically connected to winding taps 8 and 10 of the transformer TX1. The other end of capacitor C3 is electrically connected to diode D5. Diode D5 is also electrically connected to winding taps 8 and 10 of the transformer TX1. Transistor Q2 and capacitor C3 are electrically connected to pin VDD. Zener diode ZD2 and capacitor C3 are electrically connected to terminal V1-.

[0059] The BAT port is equipped with terminals BAT+ and BAT-, and the voltage of the BAT port is Vbat. One end of the winding taps 1 and 3 of the transformer TX1 is electrically connected to diode D3, and the other end of the winding taps 1 and 3 of the transformer TX1 is electrically connected to capacitor EC2. Diode D3 is electrically connected to the other end of capacitor EC2. One end of capacitor EC2 is electrically connected to diode D4, and the other end of capacitor EC2 is electrically connected to the BAT auxiliary power supply circuit. The other end of diode D4 is electrically connected to the BAT auxiliary power supply circuit. Vbat is connected between diode D4 and the BAT auxiliary power supply circuit. The connection between capacitor EC2 and the BAT auxiliary power supply circuit is connected to terminal BAT-.

[0060] The high-voltage DC power V1 is input to the high-voltage auxiliary power supply circuit through terminals V1+ and V1-, and is transmitted to its winding taps 1 and 3 through transformer TX1 for isolation. It is then rectified and filtered by diode D3 and EC2 to output Vdc.

[0061] It should be noted that in this embodiment, the control chip U2 is ON Semiconductor's UC3845 chip. The high-voltage DC power V1 is regulated by voltage divider through current-limiting resistors R3, R4, R6 and Zener diodes ZD1 and ZD2, driving the turn-on transistor Q2 to conduct. The high-voltage DC power V1 charges capacitor C3 through R5 and Q2 to supply the UC3845 chip. After reaching the turn-on voltage, the high-voltage auxiliary power supply circuit chip module is activated and outputs a PWM control signal to drive the MOSFET Q3 to work. At the same time, the high-voltage DC power V1 outputs Vdc at a reduced voltage. A small part of the energy is transferred to VDD through winding 10-8, capacitor C3 and diode D5 for rectification and power supply, so that the high-voltage auxiliary power supply circuit chip can work continuously and control the flyback power supply circuit to continuously output Vdc. Resistor R7 is a current sampling resistor used to sample the current flowing through Q3 for chip control and protection. After Vdc is output, it is transmitted to Vbat through unidirectional conduction diode D4.

[0062] The BAT auxiliary power supply circuit is electrically connected to the inverter's main power circuit. The BAT auxiliary power supply circuit is a flyback isolated DC-DC power supply circuit. The BAT auxiliary power supply circuit is used to isolate and convert the BAT port voltage Vbat or DC voltage Vdc to output voltages such as 12V, 5V, and 3.3V to supply the inverter's main power circuit (such as the power consumption of the inverter control system, cooling fan, relay control, etc., for example, the system requires 50W of power at full power). The BAT auxiliary power supply circuit is designed for full power load, and the DC voltage Vdc is less than or equal to the minimum value of the battery port voltage Vbat.

[0063] It should be noted that the BAT auxiliary power supply circuit has two energy sources, with the higher voltage being prioritized for utilization: ① the BAT port voltage Vbat; ② the output voltage from the upstream auxiliary power supply (here referring to the output voltage Vdc of the high-voltage auxiliary power supply circuit). The Vbat voltage can come from battery power or from the inverter power circuit working in reverse to charge the battery port with PV or AC energy (charging to this battery connection port regardless of whether a battery is connected). Furthermore, the circuit design ensures that Vdc ≤ Vbat_min. Therefore, the BAT auxiliary power supply circuit prioritizes the consumption of the Vbat port voltage. The high-voltage auxiliary power supply circuit only operates at low power for a short period before entering an unloaded state. The high-voltage auxiliary power supply circuit only requires a low-power capacity design, resulting in a significant reduction in circuit size and cost advantages.

[0064] The AC output port is provided with terminals L and N; the inverter main power circuit is provided with a first DC / DC circuit, which is electrically connected to terminals BAT+ and BAT- of the BAT port. The first DC / DC circuit is also electrically connected to a second DC / DC circuit through an isolation transformer. The second DC / DC circuit is electrically connected to the DC / AC circuit of the inverter main power circuit. A third DC / DC circuit is electrically connected between the second DC / DC circuit and the DC / AC circuit. The DC / AC circuit is electrically connected to terminals AC-L and AC-N of the AC input port to connect to the AC grid voltage Vac. The DC / AC circuit is also electrically connected to terminals L and N of the AC output port. The third DC / DC circuit is electrically connected to terminals PV+ and PV- of the PV input port to connect to the photovoltaic panel voltage Vpv.

[0065] An automatic switching circuit is provided between the DC / AC circuit and the AC input port, and an automatic switching circuit is also provided between the DC / AC circuit and the AC output port.

[0066] It should be noted that: the first and second DC / DC circuits, together with the isolation transformer, form the battery boost DC / DC circuit section, typically a full-bridge + full-bridge circuit or a push-pull + full-bridge circuit. Energy flows from left to right for battery discharge and from right to left for battery charging. The DC / AC section circuit is typically an H-bridge circuit, operating in H-bridge inverter mode during discharge and in bridgeless PFC mode during AC charging. The third DC / DC circuit is typically a boost-type boost circuit. Example 1:

[0067] When the inverter battery port is normally powered, regardless of whether the inverter is in standby or normal operation mode, when voltage is connected to the PV port or AC port, the high-voltage auxiliary power supply circuit will automatically start and isolate the output Vdc. The input of Vdc will cause the BAT auxiliary power supply circuit to automatically start and isolate the output of 12V, 5V, 3.3V, etc. to supply the various functional circuits of the inverter. Due to the presence of PV or AC, the inverter controls the main power circuit to switch from the inverter state to the charging state to charge the battery port. Since Vdc≤Vbat, the BAT auxiliary power supply circuit will preferentially consume the energy of Vbat converted from PV or AC through the power circuit. Example 2:

[0068] When the battery at the inverter's BAT port is disconnected or in a dormant state, the high-voltage auxiliary power circuit will automatically start after the PV voltage or AC voltage is connected (the PV micro-auxiliary power circuit will start first when PV is connected), outputting Vdc. Then, the BAT auxiliary power circuit can be activated. The inverter's main control chip controls the main power circuit to deliver energy from right to left, charging the BAT port and outputting Vbat (i.e., the voltage between BAT+ and BAT-). Since Vbat ≥ Vdc, the main energy source for the BAT auxiliary power circuit is then provided by Vbat, and the high-voltage auxiliary power circuit enters an unloaded state.

[0069] As can be seen from Examples 1 and 2, the high-voltage auxiliary power supply circuit only needs to operate for a short time with low power (only the inverter control system consumes power, for example, 15W power consumption) to supply the BAT auxiliary power supply circuit so that the inverter is activated and starts up to enter the charging state. After that, the input source of the BAT auxiliary power supply circuit is changed to Vbat converted by the power circuit, and the high-voltage auxiliary power supply circuit immediately switches to an unloaded state. Therefore, the high-voltage auxiliary power supply circuit only needs to be designed with low power capacity. The component specifications, transformer volume, circuit board area, etc. of the high-voltage auxiliary power supply circuit can all be halved. The heat sinks of MOSFETs and diodes can be removed, and the design cost is greatly reduced.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A photovoltaic inverter auxiliary power supply circuit system, characterized in that, It includes a BAT auxiliary power supply circuit, a high-voltage auxiliary power supply circuit, a PV micro auxiliary power supply circuit, and a switching circuit. The PV micro auxiliary power supply circuit is electrically connected to and controls the switching circuit. The switching circuit is electrically connected to the high-voltage auxiliary power supply circuit. The high-voltage auxiliary power supply circuit is electrically connected to the BAT auxiliary power supply circuit. It also includes a BAT port, a PV port, an AC input port, and an AC output port. The BAT auxiliary power supply circuit is electrically connected to the battery through the BAT port. The PV micro auxiliary power supply circuit is connected to the photovoltaic panel voltage Vpv through the PV port. The switching circuit is also connected to the photovoltaic panel voltage Vpv through the PV port. The switching circuit is connected to the AC grid voltage Vac through the AC input port. The high-voltage auxiliary power supply circuit, in coordination with the switching circuit, reduces the photovoltaic panel voltage Vpv or the AC grid voltage Vac to output Vdc, and activates the BAT auxiliary power supply circuit. The switching circuit includes a relay RY1 with at least 8 pins. A coil is provided between pins 1 and 8 of the relay RY1. Pin 1 of the relay RY1 is electrically connected to terminal D of MOSFET Q1. Pin 8 of the relay RY1 is electrically connected to resistor R1. Resistor R1 is electrically connected to resistor R2. One end of resistor R2 is electrically connected to terminal S of MOSFET Q1, and the other end of resistor R2 is electrically connected to terminal G of MOSFET Q1. Resistor R2 is connected in parallel with capacitor C2, and resistor R1 is connected to voltage VCC1. The AC input port is equipped with terminal blocks AC-L and AC-N; Pins 3 and 6 of relay RY1 are common terminals of the relay. Pin 3 is electrically connected to terminal V1-, and pin 6 is electrically connected to terminal V1+. A capacitor EC1 is electrically connected between terminal V1- and terminal V1+. Pin 7 of relay RY1 is connected to terminal PV+, and pin 2 of relay RY1 is connected to terminal PV-. Pins 4 and 5 of relay RY1 are both electrically connected to rectifier bridge REC1. Rectifier bridge REC1 is electrically connected to terminal AC-N. Rectifier bridge REC1 is also electrically connected to fuse F1, and fuse F1 is electrically connected to terminal AC-L.

2. The photovoltaic inverter auxiliary power supply circuit system according to claim 1, characterized in that, The PV micro auxiliary power supply circuit is equipped with a control chip U1. The control chip U1 has a built-in MOS transistor and a feedback loop. The control chip U1 has at least 8 pins. Pins 5 to 8 of the control chip U1 are the drains of the built-in MOS transistor. Pins 1 to 2 of the control chip U1 are grounded (GND). Pin 3 of the control chip U1 is a floating NC pin. Pin 4 of the control chip U1 is the VDD operating voltage.

3. The photovoltaic inverter auxiliary power supply circuit system according to claim 2, characterized in that, The PV port is equipped with terminal block PV+ and terminal block PV-; Pins 5-8 of the control chip U1 are connected to terminal PV+. Pins 5-8 of the control chip U1 are also electrically connected to capacitor CE2. Pin 4 of the control chip U1 is electrically connected to diode D1. Pin 4 of the control chip U1 is electrically connected to capacitor C1. Pins 1-2 of the control chip U1 are electrically connected. Pins 1-2 of the control chip U1 are electrically connected to inductor L1. Pins 1-2 of the control chip U1 are also electrically connected to diode D2. Capacitor C1 is also electrically connected to diode D2 and inductor L1. Diode D1 is also electrically connected to inductor L1 and capacitor CE1. Capacitor CE1, diode D2, and capacitor CE2 are electrically connected and connected to terminal PV-. The control chip U1, together with its surrounding electronic components, forms a high-voltage BUCK circuit that converts the PV voltage of the photovoltaic panel and outputs the VCC1 voltage to the switching circuit.

4. The photovoltaic inverter auxiliary power supply circuit system according to claim 1, characterized in that, The switching circuit converts the AC mains voltage Vac, which is connected to the AC-N terminal, into a high-voltage DC voltage Vrec after rectification by the rectifier bridge REC1. The switching circuit outputs high-voltage DC power V1 to the high-voltage auxiliary power supply circuit through terminals V1- and V1+, where V1 = Vpv or Vrec.

5. The photovoltaic inverter auxiliary power supply circuit system according to claim 4, characterized in that, The high-voltage auxiliary power supply circuit is a flyback isolated DC-DC power supply circuit. The high-voltage auxiliary power supply circuit is used to isolate and convert the high-voltage DC voltage V1 into a low-voltage DC voltage Vdc, and supply the DC voltage Vdc to the BAT auxiliary power supply circuit. The high-voltage auxiliary power supply circuit is composed of a control chip, terminals, resistors, MOSFETs, transformers, Zener diodes, transistors, capacitors, and diodes electrically connected together.

6. The photovoltaic inverter auxiliary power supply circuit system according to claim 5, characterized in that, The high-voltage auxiliary power supply circuit is equipped with a control chip U2. The control chip U2 has several sets of pins. The control chip U2 is electrically connected to the terminal V1- through the pins. The control chip U2 is electrically connected to the resistor R7 through the pins. The control chip U2 is also electrically connected to the MOSFET Q3 through the pins. Specifically, the control chip U2 is electrically connected to the terminal G of the MOSFET Q3 through the pins. One pin of the control chip U2 is the VDD working voltage. The resistor R7 is also electrically connected to the terminal S of the MOSFET Q3. The terminal of the MOSFET Q3 is electrically connected to the transformer TX1. Specifically, the terminal of the MOSFET Q3 is electrically connected to the winding taps 5 and 6 of the transformer TX1. The winding taps 5 and 6 of the transformer TX1 are also electrically connected to the terminal V1+. The terminal V1+ is electrically connected to resistors R4 and R5 respectively. Resistors R4, R3, R6, Zener diodes ZD1 and ZD2 are connected in series. Resistor R5 is electrically connected to transistor Q2. Zener diodes ZD1 and ZD2 are electrically connected to transistor Q2. Transistor Q2 is also electrically connected to capacitor C3. Zener diode ZD2 is also electrically connected to capacitor C3. One end of capacitor C3 is electrically connected to winding taps 8 and 10 of the transformer TX1. The other end of capacitor C3 is electrically connected to diode D5. Diode D5 is also electrically connected to winding taps 8 and 10 of the transformer TX1. Transistor Q2 and capacitor C3 are electrically connected to pin VDD. Zener diode ZD2 and capacitor C3 are electrically connected to terminal V1-.

7. The photovoltaic inverter auxiliary power supply circuit system according to claim 6, characterized in that, The BAT port is equipped with terminals BAT+ and BAT-, and the voltage of the BAT port is Vbat. One end of the winding taps 1 and 3 of the transformer TX1 is electrically connected to diode D3, and the other end of the winding taps 1 and 3 of the transformer TX1 is electrically connected to capacitor EC2. Diode D3 is electrically connected to the other end of capacitor EC2. One end of capacitor EC2 is electrically connected to diode D4. The other end of capacitor EC2 is electrically connected to the BAT auxiliary power supply circuit. The other end of diode D4 is electrically connected to the BAT auxiliary power supply circuit. Vbat is connected between diode D4 and the BAT auxiliary power supply circuit. The capacitor EC2 is electrically connected to terminal BAT- between the BAT auxiliary power supply circuit and the terminal BAT-. The high-voltage DC power V1 is input to the high-voltage auxiliary power supply circuit through terminals V1+ and V1-, and is transmitted to its winding taps 1 and 3 through transformer TX1 for isolation. It is then rectified and filtered by diode D3 and EC2 to output Vdc.

8. A photovoltaic inverter auxiliary power supply circuit system according to claim 5 or 7, characterized in that, The BAT auxiliary power supply circuit is electrically connected to the inverter main power circuit. The BAT auxiliary power supply circuit is a flyback isolated DC-DC power supply circuit. The BAT auxiliary power supply circuit is used to isolate and convert the BAT port voltage Vbat or DC voltage Vdc to output voltages such as 12V, 5V, and 3.3V to supply the inverter main power circuit. The DC voltage Vdc is less than or equal to the minimum value of the battery port voltage Vbat.

9. The photovoltaic inverter auxiliary power supply circuit system according to claim 8, characterized in that, The AC output port is equipped with terminal block L and terminal block N; The inverter's main power circuit includes a first DC / DC circuit, which is electrically connected to terminals BAT+ and BAT- of the BAT port. The first DC / DC circuit is also electrically connected to a second DC / DC circuit via an isolation transformer. The second DC / DC circuit is electrically connected to the DC / AC circuit of the inverter's main power circuit. A third DC / DC circuit is electrically connected between the second DC / DC circuit and the DC / AC circuit. This third DC / DC circuit is electrically connected to terminals AC-L and AC-N of the AC input port to connect to the AC grid voltage Vac. It is also electrically connected to terminals L and N of the AC output port. The third DC / DC circuit is electrically connected to terminals PV+ and PV- of the PV input port to connect to the photovoltaic panel voltage Vpv. An automatic switching circuit is provided between the DC / AC circuit and the AC input port, and an automatic switching circuit is also provided between the DC / AC circuit and the AC output port.

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