Inverter power supply control circuit with dual voltage conversion and lockout protection functions

Abstract

This invention relates to the field of power supply technology, specifically disclosing an inverter power supply control circuit, control method, and inverter welding machine with dual voltage conversion and lockout protection functions. The control circuit includes an input rectifier and filter circuit, an inverter circuit, an inverter control circuit, and an AC input conversion and lockout protection control circuit. The conversion and lockout circuit includes a main control relay connected to the output terminal of the AC input circuit, a first optocoupler whose operating state is determined according to the magnitude of the total input power voltage, and a voltage multiplier relay connected in series with a third field-effect transistor at its input terminal. This invention, through the design of the AC input conversion and lockout protection control circuit, can switch the circuit's operating state according to the magnitude of the input mains voltage, better protecting circuit components and preventing damage to the inverter and aluminum electrolytic capacitors.

Description

Technical Field

[0001] This invention belongs to the field of power supply technology, specifically relating to an inverter power supply control circuit, control method, and inverter welding machine with dual voltage conversion and locking protection functions. Background Technology

[0002] As the domestic market becomes more segmented, inverter welding machines are expanding into various application areas, especially in construction sites and special locations where direct power supply is not possible. This has led to the development of single-phase 220V and two-phase 380V input inverter welding machines. However, the power control schemes of these inverter welding machines suffer from high failure rates and high costs. Furthermore, their power supply stability is poor, and they frequently misjudge input voltage fluctuations, causing damage to power filter capacitors and inverter components. Summary of the Invention

[0003] Technical Objective: To address the aforementioned technical problems, this invention provides an inverter power supply control circuit, control method, and inverter welding machine with dual voltage conversion and locking protection functions. By designing an AC input conversion and locking protection control circuit, it can switch the circuit's operating state according to the input grid voltage, thereby better protecting circuit components and preventing damage to the inverter and aluminum electrolytic capacitors.

[0004] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0005] An inverter power supply control circuit with dual voltage conversion and lockout protection functions is characterized in that it includes an AC input circuit, an input rectifier and filter circuit, an inverter circuit and an output rectifier circuit connected in sequence. The input terminal of the AC input circuit is connected to the power grid and the output terminal outputs a first AC power supply. The input rectifier and filter circuit includes a first rectifier circuit, a second rectifier circuit, a filter circuit and a voltage multiplier circuit connected in the circuit. The input rectifier and filter circuit outputs a first DC power supply.

[0006] The inverter circuit is used to invert the first DC power supply and output the second AC power supply; the output rectifier circuit is used to rectify the second AC power supply and output the second DC power supply, and the output terminal of the output rectifier circuit is provided with an output feedback circuit.

[0007] The output feedback circuit sends a feedback control signal to the inverter control circuit based on the information of the second DC power supply. The output terminal of the output feedback circuit is connected to an inverter control circuit. The inverter control circuit is used to send drive information to the inverter circuit and receive the information of the second DC power supply collected by the output feedback circuit from the output rectifier circuit.

[0008] The output terminal of the AC input circuit is provided with an AC input conversion and lockout protection control circuit, which is used to collect information of the first AC power supply, i.e., the input grid voltage. The AC input conversion and lockout protection control circuit is provided with an output terminal that sends a first signal to the input rectifier and filter circuit and an output terminal that sends a second signal to the inverter control circuit. The first signal is determined according to the information of the first AC power supply, and the second signal is determined according to the first DC power supply.

[0009] Preferably, the AC input conversion and locking protection control circuit includes a main control relay connected to the output terminal of the AC input circuit, a second field-effect transistor connected in series with the input terminal of the main control relay, a first optocoupler whose operating state is determined according to the voltage of the first AC power supply, a third field-effect transistor connected in parallel with the first optocoupler, and a voltage multiplier relay whose input terminal is connected in series with the third field-effect transistor. The normally open output terminal of the voltage multiplier relay is connected to the input terminal of the voltage multiplier circuit.

[0010] The AC input conversion and lockout protection control circuit also includes an overvoltage protection circuit. The overvoltage protection circuit has a first output terminal and a second output terminal. The first output terminal is connected to the control electrode of a unidirectional thyristor. The anode of the unidirectional thyristor is connected to a second field-effect transistor and a third field-effect transistor, respectively, to stop the main control relay and the voltage multiplier relay from working after the unidirectional thyristor is turned on. The second output terminal is connected to the input terminal of the inverter control circuit, and is used to send a command to stop the inverter control circuit from working.

[0011] The input terminal of the first optocoupler is connected via an adjustable resistor to the input terminal of the second rectifier circuit and the normally open output terminal of the voltage doubler relay, i.e., one end of the input mains voltage.

[0012] Preferably, the AC input conversion and lockout protection control circuit includes:

[0013] The system comprises a main control relay, a second field-effect transistor (FET), a tenth resistor, a sixth diode, and a ninth diode. The main control relay includes terminal one (i.e., the relay power supply terminal), terminals two, three, and four. Terminals three and four are normally open contacts. Terminal three is connected to the output terminal of the AC input circuit, and the input point of the first AC power supply is located at terminal three. Terminal four is connected to the input terminal of the first rectifier circuit. Terminal one of the main control relay is connected to the drain of the second FET via a parallel connection of the tenth resistor and the sixth diode. Terminal two is also connected to the drain of the second FET. The source of the second FET is grounded, and its gate is connected to the anode of the ninth diode.

[0014] The system comprises a voltage multiplier relay, a varistor RV1, a fifth diode, an adjustable resistor, a first optocoupler, a third field-effect transistor (FET), an eighth diode, and an eleventh diode. The voltage multiplier relay includes terminals one, two, three, and four. Terminals three and four are normally open contacts. Terminal four is connected to the cathode of the fifth diode and the input of the second rectifier circuit. Terminal four is the input point for the first AC power supply. The anode of the fifth diode is connected to the input of the first optocoupler via the adjustable resistor. Terminal three of the voltage multiplier relay is connected to the input of the voltage multiplier circuit. Terminal two of the voltage multiplier relay is connected to the drain of the third FET. Terminal one, the relay power supply terminal, is connected to the cathode of the eighth diode. The anode of the eighth diode is connected to the drain of the third FET. The source of the third FET is grounded, and its gate is connected to the anode of the eleventh diode.

[0015] The cathode of the eleventh diode is connected to the cathode of the ninth diode.

[0016] Preferably, the AC input conversion and lockout protection control circuit further includes an overvoltage protection circuit, which comprises: a third optocoupler, a fourth optocoupler, a unidirectional thyristor, a fifteenth diode, several transient voltage regulator diodes connected in series, and a resistor, wherein...

[0017] Both the third and fourth optocouplers include terminals one and two as input terminals, and terminals three and four as output terminals. Terminal two of the third optocoupler is connected to terminal one of the fourth optocoupler, and terminal two of the fourth optocoupler is grounded. Terminal one of the third optocoupler is connected to the first DC power supply output by the input rectifier and filter via several transient voltage regulator diodes and resistors connected in series. Terminal three of the fourth optocoupler outputs a high potential and is connected to the control electrode of the unidirectional thyristor via the fifteenth diode to transmit a trigger signal.

[0018] The anode of the unidirectional thyristor is connected to the cathode of the eleventh diode, which is connected to the cathode of the ninth diode. The cathode of the unidirectional thyristor is grounded.

[0019] Preferably, the first optocoupler is a TLP525G optocoupler, and the third and fourth optocouplers are PC-817 optocouplers.

[0020] Preferably, the inverter control circuit adopts a PWM pulse width modulator, and the overvoltage protection circuit includes a third optocoupler and a fourth optocoupler. The output terminal of the fourth optocoupler serves as the output terminal of the first signal and is connected to the control electrode of the unidirectional thyristor. The output terminal of the third optocoupler serves as the output terminal of the second signal and is used to output a blocking signal, which is sent to the blocking signal receiving terminal of the PWM pulse width modulator.

[0021] A control method for an inverter power supply control circuit with dual voltage conversion and lockout protection functions, characterized in that control is achieved in the following manner:

[0022] When the input grid voltage, i.e. the first AC power supply, is lower than AC280V, the control circuit will enter the input filter capacitor voltage doubling mode. That is, it will determine that the first optocoupler of the input grid is in a non-working state, the voltage doubling relay will be activated, and the aluminum electrolytic capacitor will enter the voltage doubling state.

[0023] When the input grid voltage, i.e., the first AC power supply, is in the AC280V-AC300V range or in the AC300V-AC437V range, the control circuit will determine that it is a two-phase AC380V input, that is, it will determine that the first optocoupler of the input grid has entered the working state, and the voltage doubler relay will be disconnected.

[0024] Preferably, when the input mains voltage exceeds AC437V and the voltage doubler relay malfunctions, the overvoltage protection circuit detects a high potential at the input terminals of the third and fourth optocouplers and is activated respectively.

[0025] Terminal four of the third optocoupler puts the PWM pulse width modulator pin in the inverter control circuit into the PWM silencing state.

[0026] The high potential of the terminals of the fourth optocoupler is transmitted to the control electrode trigger signal of the unidirectional thyristor through the fifteenth diode, which turns on the unidirectional thyristor and pulls down the gate potential of the second and third field-effect transistors, causing the main control relay and voltage doubler relay to stop working.

[0027] An inverter welding machine is characterized in that it includes a welding machine power supply, wherein the welding machine power supply includes the inverter power supply control circuit with dual voltage conversion and locking protection functions.

[0028] Beneficial effects: Compared with the prior art, the advantages of this invention are:

[0029] This invention adds a locking control circuit, which determines the circuit operating mode based on the specific value of the input mains voltage, thus better protecting the circuit components and preventing damage to the inverter and aluminum electrolytic capacitors. The control circuit of this invention can be implemented through a switching power supply circuit, which can reduce the circuit cost by more than 50% and alleviate cost pressure. Attached Figure Description

[0030] Figure 1 This is a structural block diagram of Embodiment 1 of the present invention;

[0031] Figure 2 This is an electronic circuit diagram of Embodiment 2 of the present invention;

[0032] Wherein, BD1-first rectifier circuit, BD2-second rectifier circuit; JD1-voltage doubler relay, JD2-main control relay; U1-first optocoupler; U2-second optocoupler, U3-third optocoupler, U4-fourth optocoupler;

[0033] R10 - 10th resistor, R11 - 11th resistor, R12 - 12th resistor, R17 - 17th resistor, R18 - 18th resistor, R23 - 23rd resistor, R27 - 27th resistor, R34 - 34th resistor;

[0034] D5 - Fifth diode, D6 - Sixth diode, D7 - Seventh diode, D8 - Eighth diode, D9 - Ninth diode, D10 - Tenth Zener diode, D11 - Eleventh diode, D12 - Twelfth diode, D13 - Thirteenth Zener diode, D15 - Fifteenth diode;

[0035] RR1 - Thermistor; RT1 - Adjustable resistor; RV1 - Varistor; Q2 - Second field-effect transistor; Q3 - Third field-effect transistor; Q5 - Unidirectional thyristor;

[0036] C1 - First aluminum electrolytic capacitor, C2 - Second aluminum electrolytic capacitor, C3 - Third aluminum electrolytic capacitor, C4 - Fourth aluminum electrolytic capacitor, C5 - Fifth aluminum electrolytic capacitor, C6 - Sixth aluminum electrolytic capacitor, C10 - Tenth capacitor, C14 - Fourteenth electrolytic capacitor, C15 - Fifteenth electrolytic capacitor, C17 - Seventeenth capacitor, C23 - Second and Third capacitors, C28 - Second and Eighth capacitor, C32 - Third and Second capacitors. Detailed Implementation

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] Example 1

[0039] like Figure 1 The diagram shown is a structural block diagram of the dual voltage conversion / locking protection control circuit of the present invention, which includes an AC input circuit, an input rectifier and filter circuit, an inverter circuit and an output rectifier circuit connected in sequence. The input terminal of the AC input circuit is connected to the power grid and the output terminal outputs a first AC power supply AC1. The input rectifier and filter circuit includes a first rectifier circuit, a second rectifier circuit, a filter circuit and a voltage multiplier circuit connected in the circuit. The input rectifier and filter circuit outputs a first DC power supply DC1.

[0040] The inverter circuit is used to invert the first DC power supply DC1 and output the second AC power supply AC2; the output rectifier circuit is used to rectify the second AC power supply AC2 and output the second DC power supply DC2, and the output terminal of the output rectifier circuit is provided with an output feedback circuit.

[0041] The output feedback circuit sends an inverter control signal to the inverter circuit based on the information of the second DC power supply DC2. The output terminal of the output feedback circuit is connected to an inverter control circuit. The inverter control circuit is used to send drive information to the inverter circuit and receive the information of the second DC power supply DC2 collected by the output feedback circuit from the output rectifier circuit.

[0042] The output terminal of the AC input circuit is provided with an AC input conversion and lockout protection control circuit, which is used to collect information of the first AC power supply AC1, i.e., the input mains voltage. The AC input conversion and lockout protection control circuit is provided with an output terminal that sends a first signal to the input rectifier filter circuit and an output terminal that sends a second signal to the inverter control circuit. The first signal is determined according to the information of the first AC power supply AC1, and the second signal is determined according to the first DC power supply DC1.

[0043] Example 2

[0044] like Figure 2 The diagram shows a specific electronic circuit diagram of an AC input voltage conversion / lockout protection control circuit. The AC mains input power is passed through a thermistor RR1, then rectified by the first rectifier circuit BD1 and the second rectifier circuit BD2, and finally filtered by a capacitor to generate DC power. This DC power is then fed into an inverter circuit, specifically an IGBT / MOS-FET inverter circuit, which converts the mains frequency DC into high-frequency AC, and then further rectifies it to convert it back to DC output.

[0045] like Figure 2 As shown, specifically, the AC input conversion and lockout protection control circuit includes:

[0046] The system comprises a main control relay JD2, a second field-effect transistor Q2, a tenth resistor R10, a seventh diode D7, and a ninth diode D9. The main control relay JD2 includes terminal one (i.e., the relay power supply terminal), terminal two, terminal three, and terminal four. Terminals three and four are normally open contacts. Terminal four is connected to the output terminal of the AC input circuit and the input terminal of the first rectifier circuit. Terminals one and two of the main control relay JD2 are control terminals. Terminal one is connected to the drain of the second field-effect transistor Q2 via a parallel connection of the tenth resistor R10 and the seventh diode D7. Terminal two is also connected to the drain of the second field-effect transistor Q2. The source of the second field-effect transistor Q2 is grounded, and its gate is connected to the anode of the ninth diode D9.

[0047] The circuit consists of a voltage multiplier relay JD1, a varistor RV1, a fifth diode D5, an adjustable resistor RT1, a first optocoupler U1, a third field-effect transistor Q3, an eighth diode D8, and an eleventh diode D11. The voltage multiplier relay JD1 includes terminals one, two, three, and four. Terminals three and four are normally open contacts. Terminal four is connected to the cathode of the fifth diode D5 and the input of the second rectifier circuit. The anode of the fifth diode D5 is connected to the input of the first optocoupler U1 via the adjustable resistor RT1. Terminal 3 of the electrical appliance JD1 is connected to the midpoint of the series-parallel connection of the voltage multiplier circuit filter capacitor; terminals 1 and 2 of the voltage multiplier relay JD1 are control terminals, terminal 2 is connected to the drain of the third field-effect transistor Q3, terminal 1 is connected to the cathode of the eighth diode D8 (relay power supply terminal), and the anode of the eighth diode D8 is connected to the drain of the third field-effect transistor Q3; the source of the third field-effect transistor Q3 is grounded, and its gate is connected to the anode of the eleventh diode D11; the adjustable resistor RT1 is used to adjust it to conform to the standard range when the power grid is powered.

[0048] In this invention, the varistor RV1 acts as a valve. When the voltage exceeds its threshold, the voltage flowing through it surges, effectively opening the valve to suppress abnormal overvoltages that frequently occur in the circuit and protect it from overvoltage damage. In this embodiment, the threshold voltage of the varistor is selected to be approximately 270V. When the power supply voltage is less than 270V, it is essentially non-conductive, while when the power supply exceeds 270V, it conducts, acting as a power detection valve switch.

[0049] The AC input conversion and lockout protection control circuit also includes an overvoltage protection circuit, connected to the cathode of the eleventh diode D11 and the cathode of the ninth diode D9. The overvoltage protection circuit includes:

[0050] The system comprises a third optocoupler U3, a fourth optocoupler U4, a second field-effect transistor Q2, a third field-effect transistor Q3, a unidirectional thyristor Q5, and a fifteenth diode D15. Both the third optocoupler U3 and the fourth optocoupler U4 include terminals one and two as input terminals, and terminals three and four as output terminals. Terminal two of the third optocoupler U3 is connected to terminal one of the fourth optocoupler U4, and terminal two of the fourth optocoupler U4 is grounded. Terminal one of the third optocoupler U4 is connected to a series of Zener diodes and resistors, which are then connected to the first DC power supply DC1 at the input rectification and filtering output. Terminal three of the fourth optocoupler U4 outputs a high potential, which is transmitted to the control electrode trigger signal of the unidirectional thyristor Q5 via the fifteenth diode D15.

[0051] The unidirectional thyristor Q5 is connected to the cathode of the eleventh diode D11, which is connected to the cathode of the ninth diode D9. The cathode of the unidirectional thyristor Q5 is grounded.

[0052] This embodiment adds a locking control circuit to the entire circuit, and implements control in the following manner:

[0053] (1) When the input grid voltage is lower than AC280V, the control circuit will enter the input filter capacitor voltage doubling mode, that is, the first optocoupler U1 (TLP525G) of the input grid is determined to be in a non-working state, the voltage doubling relay is activated, and the aluminum electrolytic capacitor enters the voltage doubling state.

[0054] (2) When the input power grid is in the range of AC280V-AC300V or AC300V-AC437V, the control circuit will determine that it is a two-phase AC380V input, that is, it will determine that the first optocoupler U1 of the input power grid enters the working state and the voltage doubler relay is disconnected.

[0055] (3) When the input voltage is 380V, and the voltage doubler relay fails and remains closed, the overvoltage protection circuit starts with dual-path control. When the overvoltage protection circuit detects an abnormal instantaneous voltage doubler of the AC380V input grid, it will control the inverter through the optocoupler PC-817. One path works through the third optocoupler U3 (PC-817) to block the 8th pin of the 3525 PWM pulse width modulator, ensuring that the inverter enters the protection state. The other path works through the second optocoupler U4 (PC-817), which will trigger the control electrode of the unidirectional thyristor Q5 (100-6), pull down the voltage at the power supply terminal of the voltage doubler relay, and stop it from working.

[0056] Figure 2 The detailed working principle of the key components is as follows:

[0057] (1) When the input grid voltage is AC220V (AC IN1 and AC IN2), the main control relay JD2 works. At the same time, the input terminals of the first optocoupler U1, namely pins 1 and 2, do not detect a high potential and do not work. At this point, the third field-effect transistor Q3 works, causing the voltage doubler relay JD1 to work and engage. After being rectified by the first rectifier circuit BD1 and the second rectifier circuit BD2, the rectified DC power supply is sent to the filter circuit composed of multiple aluminum electrolytic capacitors, namely the first aluminum electrolytic capacitor to the sixth aluminum electrolytic capacitor, to form a voltage doubler mode and generate a DC high voltage power supply to provide to the inverter circuit.

[0058] (2) When the input grid voltage is AC380V±15% (AC IN1 and AC IN2), the main control relay JD2 operates. At the same time, the input terminals (pins 1 and 2) of the first optocoupler U1 detect a high potential and operate. This high potential voltage can be adjusted between AC280V and AC300V through the adjustable resistor RT1. At this point, the potential of pin 1 of the third field-effect transistor Q3 is pulled low, and it stops working, causing the voltage doubler relay JD1 to stop working. After rectification by the first rectifier circuit BD1 and the second rectifier circuit BD2, the rectified DC power supply is sent to the filter circuit composed of multiple aluminum electrolytic capacitors, namely the first aluminum electrolytic capacitor to the sixth aluminum electrolytic capacitor, to generate a high DC voltage to supply the inverter circuit.

[0059] (3) When the input grid voltage is greater than AC380V (or the VCC voltage is greater than or equal to DC800V, where the VCC voltage is the first DC power supply DC1 output by the input rectifier filter, i.e. the main circuit inverter power supply), the input terminals (pins 1 and 2) of the third optocoupler U3 and the fourth optocoupler U4 in the overvoltage protection circuit detect a high potential and are turned on respectively.

[0060] Pin 4 of the third optocoupler U3 puts the PWM chip blocking pin of the inverter control into a blocking state, ensuring that the entire inverter circuit is not damaged.

[0061] The high potential at pin 3 of the fourth optocoupler U4 is transmitted to the control electrode trigger signal of the unidirectional thyristor Q5 (100-6) through the fifteenth diode D15, causing the unidirectional thyristor Q5 to conduct, pulling down the gate potential of the second field-effect transistor Q2 and the third field-effect transistor Q3, causing the main control relay JD2 and the voltage doubler relay JD1 to stop working, preventing damage to the aluminum electrolytic capacitors (C1 / C2 / C3 / C4 / C5 / C6) in the filter circuit.

[0062] Once the unidirectional thyristor Q5 is working, the power supply can only be turned on after the input mains switch is turned off, the fault is cleared, and the circuit is restarted.

[0063] This embodiment utilizes a rectification, filtering, and 3845 chip control circuit to implement a switching power supply circuit, reducing circuit cost by more than 50%. It solves the cost problem inherent in most existing auxiliary power supply control solutions that directly convert AC to DC using a power frequency transformer. Furthermore, it addresses the issue in general voltage conversion circuits where the control circuit cannot effectively protect the inverter, power supply aluminum electrolytic capacitors, and IGBT / MOS-FETs when the input voltage is at the critical voltage between voltage doubling and non-voltage doubling.

[0064] In another embodiment of the present invention, an inverter welding machine is provided, including a welding machine power supply, the welding machine power supply including the inverter control circuit with dual voltage conversion and locking protection functions.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An inverter power supply control circuit with dual voltage conversion and lockout protection functions, characterized in that: It includes an AC input circuit, an input rectifier and filter circuit, an inverter circuit, and an output rectifier circuit connected in sequence. The input terminal of the AC input circuit is connected to the power grid, and the output terminal outputs a first AC power supply. The input rectifier and filter circuit includes a first rectifier circuit, a second rectifier circuit, a filter circuit, and a voltage multiplier circuit connected in a circuit. The input rectifier and filter circuit outputs a first DC power supply. The inverter circuit is used to invert the first DC power supply and output the second AC power supply; the output rectifier circuit is used to rectify the second AC power supply and output the second DC power supply, and the output terminal of the output rectifier circuit is provided with an output feedback circuit. The output terminal of the output feedback circuit is connected to an inverter control circuit. The output feedback circuit sends a feedback control signal to the inverter control circuit according to the information of the second DC power supply. The inverter control circuit is used to send drive information to the inverter circuit and receive the information of the second DC power supply collected by the output feedback circuit from the output rectifier circuit. The output terminal of the AC input circuit is provided with an AC input conversion and lockout protection control circuit, which is used to collect information of the first AC power supply, i.e., the input mains voltage; the AC input conversion and lockout protection control circuit is provided with an output terminal that sends a first signal to the input rectifier and filter circuit and an output terminal that sends a second signal to the inverter control circuit, the first signal being determined according to the information of the first AC power supply and the second signal being determined according to the first DC power supply; The AC input conversion and locking protection control circuit includes a main control relay connected to the output terminal of the AC input circuit, a second field-effect transistor connected in series with the input terminal of the main control relay, a first optocoupler whose working state is determined according to the voltage of the first AC power supply, a third field-effect transistor connected in parallel with the first optocoupler, and a voltage multiplier relay whose input terminal is connected in series with the third field-effect transistor. The normally open output terminal of the voltage multiplier relay is connected to the input terminal of the voltage multiplier circuit. The AC input conversion and lockout protection control circuit also includes an overvoltage protection circuit. The overvoltage protection circuit has a first output terminal and a second output terminal. The first output terminal is connected to the control electrode of a unidirectional thyristor. The anode of the unidirectional thyristor is connected to a second field-effect transistor and a third field-effect transistor, respectively, to stop the main control relay and the voltage multiplier relay from working after the unidirectional thyristor is turned on. The second output terminal is connected to the input terminal of the inverter control circuit, and is used to send a command to stop the inverter control circuit from working. The input terminal of the first optocoupler is connected to the input terminal of the second rectifier circuit and the normally open output terminal of the voltage doubler relay via an adjustable resistor, which is one of the input mains voltage terminals; The inverter control circuit uses a PWM pulse width modulator, and the overvoltage protection circuit includes a third optocoupler and a fourth optocoupler. The output terminal of the fourth optocoupler serves as the output terminal of the first signal and is connected to the control electrode of the unidirectional thyristor. The output terminal of the third optocoupler serves as the output terminal of the second signal and is used to output a blocking signal, which is sent to the blocking signal receiving terminal of the PWM pulse width modulator.

2. The inverter power supply control circuit with dual voltage conversion and lockout protection functions according to claim 1, characterized in that: The AC input conversion and lockout protection control circuit includes: The system comprises a main control relay, a second field-effect transistor (FET), a tenth resistor, a sixth diode, and a ninth diode. The main control relay includes terminal one (power supply terminal), terminals two, three, and four. Terminals three and four are normally open contacts. Terminal three is connected to the output terminal of the AC input circuit, and the input point of the first AC power supply is located at terminal three. Terminal four is connected to the input terminal of the first rectifier circuit. Terminal one of the main control relay is connected to the drain of the second FET via a parallel connection of the tenth resistor and the sixth diode. Terminal two is also connected to the drain of the second FET. The source of the second FET is grounded, and its gate is connected to the anode of the ninth diode. The system comprises a voltage multiplier relay, a varistor, a fifth diode, an adjustable resistor, a first optocoupler, a third field-effect transistor (FET), an eighth diode, and an eleventh diode. The voltage multiplier relay includes terminals one, two, three, and four. Terminals three and four are normally open contacts. Terminal four is connected to the cathode of the fifth diode and the input of the second rectifier circuit. Terminal four is used as a detection point for the first AC power supply. The anode of the fifth diode is connected to the input of the first optocoupler via the adjustable resistor. Terminal three of the voltage multiplier relay is connected to the input of the voltage multiplier circuit. Terminal two of the voltage multiplier relay is connected to the drain of the third FET. Terminal one, the relay power supply terminal, is connected to the cathode of the eighth diode. The anode of the eighth diode is connected to the drain of the third FET. The source of the third FET is grounded, and its gate is connected to the anode of the eleventh diode. The cathode of the eleventh diode is connected to the cathode of the ninth diode.

3. The inverter power supply control circuit with dual voltage conversion and lockout protection functions according to claim 2, characterized in that: The AC input conversion and lockout protection control circuit also includes an overvoltage protection circuit, which comprises: a third optocoupler, a fourth optocoupler, a unidirectional thyristor, a fifteenth diode, several transient voltage regulator diodes connected in series, and a resistor. Both the third and fourth optocouplers include terminals one and two as input terminals, and terminals three and four as output terminals. Terminal two of the third optocoupler is connected to terminal one of the fourth optocoupler, and terminal two of the fourth optocoupler is grounded. Terminal one of the third optocoupler is connected to the first DC power supply output by the input rectifier and filter via several transient voltage regulator diodes and resistors connected in series. Terminal three of the fourth optocoupler outputs a high potential and is connected to the control electrode of the unidirectional thyristor via the fifteenth diode to transmit a trigger signal. The anode of the unidirectional thyristor is connected to the cathode of the eleventh diode, which is connected to the cathode of the ninth diode. The cathode of the unidirectional thyristor is grounded.

4. The inverter power supply control circuit with dual voltage conversion and lockout protection functions according to claim 3, characterized in that: The first optocoupler is a TLP525G optocoupler, and the third and fourth optocouplers are PC-817 optocouplers.

5. A control method using the inverter power supply control circuit with dual voltage conversion and lockout protection functions as described in any one of claims 1-4, characterized in that, Control is achieved in the following manner: When the input grid voltage, i.e. the first AC power supply, is lower than AC280V, the control circuit will enter the input filter capacitor voltage doubling mode. That is, it will determine that the first optocoupler of the input grid is in a non-working state, the voltage doubling relay will be activated, and the aluminum electrolytic capacitor will enter the voltage doubling state. When the input grid voltage, i.e., the first AC power supply, is in the AC280V-AC300V range or in the AC300V-AC437V range, the control circuit will determine that it is a two-phase AC380V input, that is, it will determine that the first optocoupler of the input grid has entered the working state, and the voltage doubler relay will be disconnected.

6. The control method for the inverter power supply control circuit with dual voltage conversion and lockout protection functions according to claim 5, characterized in that: When the input mains voltage exceeds AC437V and the voltage doubler relay malfunctions, the overvoltage protection circuit detects a high potential at the input terminals of the third and fourth optocouplers and is activated respectively. Terminal four of the third optocoupler puts the PWM pulse width modulator pin in the inverter control circuit into the PWM silencing state. The high potential of the terminals of the fourth optocoupler is transmitted to the control electrode trigger signal of the unidirectional thyristor through the fifteenth diode, which turns on the unidirectional thyristor and pulls down the gate potential of the second and third field-effect transistors, causing the main control relay and voltage doubler relay to stop working.

7. An inverter welding machine, characterized in that: The power supply includes a welding machine power supply, which includes an inverter power control circuit with dual voltage conversion and lockout protection functions as described in any one of claims 1-4.

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