Dual single tube voltage clamping diode inverter dual system high frequency circuit for welding machine

Abstract

The present invention discloses a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine, including a DC input unit, a dual-single-tube forward dual-system inverter circuit unit, a DC output unit, a PWM circuit and an isolation driving circuit, wherein the dual-single-tube forward dual-system inverter circuit unit includes a first dual-single-tube forward inverter circuit unit and a second dual-single-tube forward inverter circuit unit. The present invention realizes synchronous conduction and shutdown of the power switch tube, which is consistent with the working efficiency of a single tube; the driving waveform of the dual system composed of the first dual-single-tube forward inverter circuit unit and the second dual-single-tube forward inverter circuit unit is forced to be misaligned, and the effect achieved is that the two systems work alternately in an excitation state. The essence of the alternating operation of the two systems is that the first high-frequency transformer and the second high-frequency transformer alternately input and output AC voltage, and the secondary voltage phase sequence is staggered, achieving the effect of increasing the frequency and increasing the power by voltage superposition, and then obtaining a DC voltage output through rectification and filtering.

Description

Technical Field

[0001] The invention relates to a high-frequency circuit, in particular to a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine. Background Art

[0002] There are many types of power devices, but the power devices suitable for high-power, high-voltage and high-frequency applications are limited by different materials, manufacturing costs and technologies. The current power devices suitable for high-frequency inverters mainly include VMOS, IGBT and new devices produced by silicon carbide technology (silicon carbide is a more advanced new semiconductor developed on the basis of silicon semiconductors. Its characteristics are that the power devices composed of it exceed silicon semiconductor materials in terms of large current, high voltage resistance and response speed.).

[0003] VMOS is the most suitable for high-frequency power conversion, with high frequency and low conduction loss, but its withstand voltage level is limited to a certain level, which is not applicable to the 380V three-phase power supply voltage level. Although there are electrical technologies that can achieve high-voltage and high-power mature applications, the cost structure is not applicable as this report is limited to large-scale products for civil and industrial use. The electrical construction principle of VMOS limits its withstand voltage level.

[0004] IGBT is a device that is derived from the advantages of both transistors and MOS tubes and is very suitable for ultra-high power inverter applications. It has promoted the leap forward of inverter power products. Existing mature application products are divided into two categories: single-tube package and module. Among them, the single-tube package IGBT high-frequency performance type Infineon's third-generation high-speed series single-tube package IGBT can reach a switching frequency of 70KHz while maintaining the rated electrical parameters; the popularized large-scale production application wafer can also reach a switching frequency of at least 40KHz while maintaining the rated electrical parameters. Module package IGBT is generally a half-bridge package below 300A. It is very stable and reliable in the super-audio range (20KHz), and the total value of various losses is relatively low. However, the loss increases significantly beyond this frequency range, that is, it is no longer applicable. The electrical structure principle of the module package IGBT limits its switching frequency level.

[0005] The switching power supply circuit of single-tube excitation is characterized by simple circuit and wide voltage operating range. Its disadvantage is that the voltage level of the power switch tube driven by the primary coil excitation current is high, the circuit conversion efficiency is low, and it is only suitable for small power. Switching power supplies are widely used.

[0006] In the half-bridge inverter technology, two sets of driving waveforms with a certain dead time act on two IGBT tubes respectively, in an alternating drive conduction form. Two capacitors are connected to the lower end of the primary coil of the inverter isolation transformer, and their voltage is 1 / 2 of the DC voltage of the power supply. When the first switch tube is turned on, the second switch tube is turned off, and the DC voltage of the power supply is positively loaded to the lower end of the primary coil of the transformer. In this way, a voltage difference is formed between the upper and lower ends of the primary coil of the inverter isolation transformer, forming an excitation current. After the first switch tube is turned off, after a dead time delay, the second switch tube is turned on, and the DC voltage of the power supply is negatively loaded to the lower end of the primary coil of the transformer. A negative voltage difference is formed between the upper and lower ends of the primary coil of the inverter isolation transformer, forming an excitation current with the opposite polarity to that when the first switch tube is turned on. In this way, an alternating reverse polarity excitation current is formed on the primary coil of the inverter isolation transformer, and the secondary induced electromotive force also forms an alternating form, and the inversion is formed. Compared with the single-tube excitation mode, this technology utilizes the bipolar excitation of the inverter isolation transformer, and has high electromagnetic conversion efficiency. However, the disadvantage of half-bridge inverter is that half of the bridge arm is realized by capacitors compared to the full-bridge mode, and its voltage variation range is halved. Under the same output rated power condition, the primary current needs to be twice as large. It is also the capacitor that bears the electrical function of the bridge arm. The inherent defects of the half-bridge circuit are reflected in the obvious lack of response speed of output electrical parameter adjustment. When the half-bridge inverter circuit is generally applied to welding products, it is limited to manual arc welding type power supply with reduced characteristics, and cannot be competent for power supply with high dynamic characteristics.

[0007] The push-pull inverter is very similar to the half-bridge circuit. First, its driving signal is consistent, and the two power tubes are turned on alternately. It does not have the dynamic characteristics disadvantages caused by the capacitor in the half-bridge inverter. However, its performance is mainly limited by the process of the inverter isolation transformer, and it is not suitable for higher power mode.

[0008] The H-bridge inverter circuit is a double half-bridge structure with no capacitor as the bridge arm, which completely overcomes the dynamic characteristics disadvantages brought by the capacitor in the half-bridge inverter. Compared with the half-bridge structure, the new disadvantage is that the process error when the primary and secondary coils of the transformer are formed will form a DC bias magnetic component during the inverter process. Generally, it is necessary to add a DC blocking capacitor and four switch tubes. The four switch tubes also need a period of time to protect all of them from being turned off, which is the dead time. The H-bridge inverter circuit has become the most important mode of choice for welding power supplies, mainly because it matches the existing mature IGBT half-bridge package module and has been very stable and reliable in the ultra-audio (20KHz) range. The single module half-bridge package structure has reached 300A / 1700V. The H-bridge inverter circuit composed of two 150A / 1200V modules matched with the ONL1308060 ultra-microcrystalline core can achieve a continuous output efficiency of 27KVA. The defects of H-bridge inverter circuit: On the one hand, the module package IGBT with larger current cannot realize the inverter switch in the super-audio range, and the loss exceeds the package thermal specification value; on the other hand, the existing IGBT single-tube package enables the single wafer process technology to achieve sufficient loss reduction and form a response speed that adapts to higher frequencies. Infineon's third-generation high-speed series single-tube package IGBT can reach a switching frequency of 70KHz while maintaining the rated electrical parameters; the popularized large-scale production and application wafers can also reach a switching frequency of at least 40KHz while maintaining the rated electrical parameters. The reliability and cost-price ratio of the products in the formation of high-power and ultra-high-power inverter systems determine whether they are suitable for civil industrial products. The process complexity of IGBT single tubes to form ultra-high-power inverter systems increases by more than several levels, and there are also hidden dangers that cannot be absolutely controlled; even if the hidden dangers can be overcome to the maximum extent through sufficient design and advanced equipment process guarantees, factors such as the product cost increase rate and maintenance convenience will become new secondary hidden dangers of the product, and thus cannot be adopted by large-scale products. Summary of the invention

[0009] The technical problem to be solved by the present invention is to overcome the defects in the prior art. A dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine is provided. The driving waveform of the dual system is twice the driving waveform of the dual-single-tube voltage-embedded diode inverter circuit. In particular, the driving waveform of the dual system composed of the first dual-single-tube forward inverter circuit unit and the second dual-single-tube forward inverter circuit unit is forced to be staggered, so that the two systems work alternately in an excitation state. The essence of the alternating operation of the two systems is that the first high-frequency transformer and the second high-frequency transformer alternately input and output AC voltage, and the secondary voltage phase sequence is staggered. In addition, a parallel rectification mode is adopted, and the frequency is superimposed, so that the voltage is superimposed to increase the frequency and increase the power, and then a DC voltage output is obtained through rectification and filtering.

[0010] The present invention solves the above technical problems through the following technical solutions:

[0011] A dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine, characterized in that the dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine includes a DC input unit, a dual-single-tube forward dual-system inverter circuit unit, a DC output unit, a PWM circuit and an isolation driving circuit, the dual-single-tube forward dual-system inverter circuit unit includes a first dual-single-tube forward inverter circuit unit and a second dual-single-tube forward inverter circuit unit, the first dual-single-tube forward inverter circuit unit includes a first voltage-embedded diode, a second voltage-embedded diode, a first anti-parallel diode, a second anti-parallel diode, a first A power switch tube, a second power switch tube and a first high-frequency transformer, the second dual-single-tube forward inverter circuit unit includes a third voltage clamping diode, a fourth voltage clamping diode, a third anti-parallel diode, a fourth anti-parallel diode, a third power switch tube, a fourth power switch tube and a second high-frequency transformer, the same-name end and the opposite-name end of the secondary coil of the first high-frequency transformer are respectively connected to the positive and negative poles of the DC output unit, the same-name end and the opposite-name end of the secondary coil of the second high-frequency transformer are respectively connected to the positive and negative poles of the DC output unit, the isolation driving circuit is connected to the PWM circuit, wherein:

[0012] The collector of the first power switch tube is connected in parallel to the positive electrode of the DC input unit, the cathode of the first voltage clamping diode and the cathode of the first anti-parallel diode, the base of the first power switch tube is connected to the first end of the isolation driving circuit, the emitter of the first power switch tube is connected in parallel to the cathode of the second voltage clamping diode, the anode of the first anti-parallel diode, the same-name end of the primary coil of the high-frequency transformer and the second end of the isolation driving circuit, the collector of the second power switch tube is connected in parallel to the anode of the first voltage clamping diode, the cathode of the second anti-parallel diode and the opposite-name end of the primary coil of the first high-frequency transformer, the base of the second power switch tube is connected to the third end of the isolation driving circuit, and the emitter of the second power switch tube is connected in parallel to the anode of the second voltage clamping diode, the anode of the second anti-parallel diode, the fourth end of the isolation driving circuit and the negative electrode of the DC input unit;

[0013] The collector of the third power switch tube is connected in parallel to the positive electrode of the DC input unit, the cathode of the third voltage clamping diode and the cathode of the third anti-parallel diode, the base of the third power switch tube is connected to the fifth end of the isolation driving circuit, the emitter of the third power switch tube is connected in parallel to the cathode of the fourth voltage clamping diode, the anode of the third anti-parallel diode, the same-name end of the primary coil of the second high-frequency transformer and the sixth end of the isolation driving circuit, the collector of the fourth power switch tube is connected in parallel to the anode of the third voltage clamping diode, the cathode of the fourth anti-parallel diode and the opposite-name end of the primary coil of the second high-frequency transformer T2, the base of the fourth power switch tube is connected to the seventh end of the isolation driving circuit, and the emitter of the fourth power switch tube is connected in parallel to the positive electrode of the fourth voltage clamping diode, the anode of the fourth anti-parallel diode, the eighth end of the isolation driving circuit and the negative electrode of the DC input unit.

[0014] Preferably, the first dual single-tube forward inverter circuit unit also includes a first current limiting resistor and a second current limiting resistor, the first current limiting resistor is arranged to be connected between the base of the first power switch tube and the first end of the isolation driving circuit, and the second current limiting resistor is arranged to be connected between the base of the second power switch tube and the third end of the isolation driving circuit; the second dual single-tube forward inverter circuit unit also includes a third current limiting resistor and a fourth current limiting resistor, the third current limiting resistor is arranged to be connected between the base of the third power switch tube and the fifth end of the isolation driving circuit, and the fourth current limiting resistor is arranged to be connected between the base of the fourth power switch tube and the seventh end of the isolation driving circuit.

[0015] Preferably, the DC input unit includes an AC voltage input terminal, a rectifier circuit, a first DC input processing unit and a second DC input processing unit, the first DC input processing unit includes a first capacitor, a first electrolytic capacitor, a second electrolytic capacitor, a first voltage balancing and discharge resistor and a second voltage balancing and discharge resistor, the second DC input processing unit includes a second capacitor, a third electrolytic capacitor, a fourth electrolytic capacitor, a third voltage balancing and discharge resistor and a fourth voltage balancing and discharge resistor, the AC voltage input terminal is connected to the rectifier circuit, and the positive terminal of the rectifier circuit is connected in parallel to one end of the first capacitor, the positive electrode of the first electrolytic capacitor and one end of the first voltage balancing and discharge resistor, and one end of the second capacitor. end, the positive electrode of the third electrolytic capacitor and one end of the third balancing and discharge resistor, the negative end of the rectifier circuit is grounded and connected in parallel to the other end of the first capacitor, the negative electrode of the second electrolytic capacitor, one end of the second balancing and discharge resistor, the other end of the second capacitor, the negative electrode of the fourth electrolytic capacitor and one end of the fourth balancing and discharge resistor, the negative electrode of the first electrolytic capacitor, the positive electrode of the second electrolytic capacitor, the other end of the first balancing and discharge resistor and the other end of the second balancing and discharge resistor are connected, the negative electrode of the third electrolytic capacitor, the positive electrode of the fourth electrolytic capacitor, the other end of the third balancing and discharge resistor and the other end of the fourth balancing and discharge resistor are connected.

[0016] Preferably, the DC output unit includes a first DC output processing unit, a second DC output processing unit, an inductor, a load maintaining resistor and a voltage output terminal, the first DC output processing unit includes a first absorption current limiting resistor, a second absorption current limiting resistor, a first absorption capacitor, a second absorption capacitor, a first high-frequency rectifier fast recovery diode and a first freewheeling fast recovery diode, the second DC output processing unit includes a third absorption current limiting resistor, a fourth absorption current limiting resistor, a third absorption capacitor, a fourth absorption capacitor, a second high-frequency rectifier fast recovery diode and a second freewheeling fast recovery diode, the same-name end of the secondary coil of the second high-frequency transformer is connected in parallel to one end of the third absorption current limiting resistor and the anode of the second high-frequency rectifier fast recovery diode, the same-name end of the secondary coil of the first high-frequency transformer is connected in parallel to one end of the first absorption current limiting resistor and the anode of the first high-frequency rectifier fast recovery diode, and the opposite-name end of the secondary coil of the high-frequency transformer is connected in parallel to the second absorption current limiting resistor. One end of the resistor, the anode of the first freewheeling fast recovery diode and the one end of the inductor, the other end of the second absorption current limiting resistor is connected to one end of the second absorption capacitor, the opposite end of the secondary coil of the high-frequency transformer is connected in parallel to one end of the fourth absorption current limiting resistor, the anode of the second freewheeling fast recovery diode and the one end of the inductor, the other end of the fourth absorption current limiting resistor is connected to one end of the fourth absorption capacitor, the other end of the first absorption capacitor is connected in parallel to the other end of the second absorption capacitor, the other end of the third absorption capacitor, the other end of the fourth absorption capacitor, the cathode of the first high-frequency rectifier fast recovery diode, the cathode of the first freewheeling fast recovery diode, the cathode of the second high-frequency rectifier fast recovery diode, the cathode of the second freewheeling fast recovery diode, one end of the load maintenance resistor and the positive end of the voltage output end are connected, and the other end of the inductor is connected to the other end of the load maintenance resistor and the negative end connected to the voltage output end.

[0017] Preferably, the DC output unit further comprises an output load resistor for maintaining a no-load state, one end of the load resistor is connected to the cathodes of the first and second high-frequency rectifier diodes, and the other end of the load resistor is connected to the other end of the inductor.

[0018] A device provided with a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine, characterized in that the device provided with a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine is any of the above-mentioned dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuits for a welding machine.

[0019] The positive and progressive effects of the present invention are:

[0020] The present invention adopts dual-single-tube technology and combines dual-embedded diodes to solve the drawback of the VMOS tube withstand voltage level limitation, and realizes the addition of a dual-single-tube forward inverter circuit unit on the technical basis of the single-tube excitation mode circuit structure, and the switch tube from the primary coil of the inverter isolation transformer to the power supply and the diode to the ground, forming a reliable primary coil voltage embedding; the voltage level does not exceed the DC power supply voltage, and is in an absolutely safe working environment; the energy utilization rate is greatly improved, and the overall conversion efficiency is greatly improved compared with the single-tube mode; the present invention adopts a dual-system driving waveform that is twice the driving waveform of the dual-single-tube voltage embedded diode inverter circuit, especially the driving waveform of the dual system composed of the first dual-single-tube forward inverter circuit unit and the second dual-single-tube forward inverter circuit unit is forced to be staggered, so that the two systems work alternately in the excitation state, and the essence of the alternating operation of the two systems is that the first high-frequency transformer and the second high-frequency transformer alternately input and output AC voltage, and the secondary voltage phase sequence is staggered, and the parallel rectification mode is adopted, and the frequency is superimposed, so that the voltage superposition increases the frequency and increases the power, and then the DC voltage output is obtained through rectification and filtering. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The overall structural diagram of a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine according to a preferred embodiment of the present invention.

[0022] Figure 2 It is a schematic diagram of the overall structure of a preferred embodiment of the present invention.

[0023] Figure 3 It is a waveform diagram of the short-circuit transition droplet time and voltage in CO2 welding of the present invention.

[0024] Figure 4 It is a waveform diagram of the short-circuit transition droplet time and current in CO2 welding of the present invention.

[0025] Figure 5 This is a schematic diagram of the structure of the product to be welded.

[0026] Figure 6 For welding current Figure 5 Schematic diagram of the waveform that affects the weld formation.

[0027] Figure 7 For welding voltage Figure 5 Schematic diagram of the waveform that affects the weld formation.

[0028] Figure 8 For welding speed Figure 5 Schematic diagram of the waveform that affects the weld formation. DETAILED DESCRIPTION

[0029] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0030] Inverter power supply for welding has been maturely applied in the formation and mass production of products, but for the further development and application of welding power supply, how to reduce the requirements of manual technology for welding, how to make welding easier to achieve high efficiency and high quality, this fundamentally requires a significant increase in the inverter conversion frequency. As long as the inverter frequency can be increased to a certain point, the adaptive electrical capacity in welding will be relatively improved by one level. At the same time, precision and accurate welding will also be improved to the point where the control is fully and effectively reflected in the weld formation. As a result, manual welding can achieve high-quality semi-automatic welding (CO2 welding) with simple control, and when matching the high-speed welding and micro-current precision welding of robot automatic welding, the characteristics of the robot system or some welding machine mechanisms are fully utilized based on this adaptability and control accuracy effectiveness.

[0031] As shown in 1, the present invention is a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine, which includes a DC input unit 1, a dual-single-tube forward dual-system inverter circuit unit 2, a DC output unit 5, a PWM circuit 4 and an isolation driving circuit 3. The isolation driving circuit 3 is used for width control of the power switch tube drive waveform, and the PWM circuit 4 is used for operation control, power supply control and protection control. The dual-single-tube forward dual-system inverter circuit unit 2 includes a first dual-single-tube forward inverter circuit unit 21 and a second dual-single-tube forward inverter circuit unit 22. The first dual-single-tube forward inverter circuit unit 21 includes a first dual-single-tube forward inverter circuit unit including a first voltage clamping diode D1, a second voltage clamping diode D2, a first anti-parallel diode D3, a second anti-parallel diode D4, a first power switch tube Q1, a second power switch tube Q2 and a first high-frequency transformer T1. The second dual-single-tube forward inverter circuit unit includes a third voltage clamping diode D5, a fourth voltage clamping diode D6, a third anti-parallel diode D7, a fourth anti-parallel diode D8, a third power switch tube Q3, a fourth power switch tube Q4 and a second high-frequency transformer T2. The same-name end and the opposite-name end of the secondary coil of the first high-frequency transformer are respectively connected to the positive and negative poles of the DC output unit. The same-name end and the opposite-name end of the secondary coil of the second high-frequency transformer are respectively connected to the positive and negative poles of the DC output unit. The isolation driving circuit is connected to the PWM circuit.

[0032] The collector of the first power switch tube Q1 is connected in parallel to the positive electrode of the DC input unit, the cathode of the first voltage clamping diode D1 and the cathode of the first anti-parallel diode D3, the base of the first power switch tube is connected to the first end of the isolation driving circuit through the driving current limiting resistor R1, the emitter of the first power switch tube is connected in parallel to the cathode of the second voltage clamping diode D2, the anode of the first anti-parallel diode D3, the same-name end of the primary coil of the high-frequency transformer T1 and the second end of the isolation driving circuit, the collector of the second power switch tube Q2 is connected in parallel to the anode of the first voltage clamping diode D1, the cathode of the second anti-parallel diode D4 and the opposite-name end of the primary coil of the first high-frequency transformer T1, the base of the second power switch tube Q2 is connected to the third end of the isolation driving circuit through the driving current limiting resistor R2, and the emitter of the second power switch tube Q2 is connected in parallel to the anode of the second voltage clamping diode D2, the anode of the second anti-parallel diode D4, the fourth end of the isolation driving circuit and the negative electrode of the DC input unit;

[0033] The collector of the third power switch tube Q3 is connected in parallel to the positive electrode of the DC input unit, the cathode of the third voltage clamping diode D5 and the cathode of the third anti-parallel diode D7. The base of the third power switch tube Q3 is connected to the fifth end of the isolation driving circuit through the driving current limiting resistor R3. The emitter of the third power switch tube Q3 is connected in parallel to the cathode of the fourth voltage clamping diode D6, the anode of the third anti-parallel diode D7, the same-name end of the primary coil of the second high-frequency transformer T2 and the sixth end of the isolation driving circuit. The collector of the fourth power switch tube Q4 is connected in parallel to the anode of the third voltage clamping diode D5, the cathode of the fourth anti-parallel diode D8 and the opposite end of the primary coil of the second high-frequency transformer T2, the base of the fourth power switch tube Q4 is connected to the seventh end of the isolation driving circuit through the driving current limiting resistor R4, and the emitter of the fourth power switch tube Q4 is connected in parallel to the positive electrode of the fourth voltage clamping diode D6, the anode of the fourth anti-parallel diode D8, the eighth end of the isolation driving circuit and the negative electrode of the DC input unit.

[0034] The present invention adopts dual-single-tube technology and combines dual-embedded diodes to solve the drawback of the voltage resistance level limitation of the VMOS tube, and realizes the addition of a dual-single-tube forward inverter circuit unit on the technical basis of the single-tube excitation mode circuit structure, and the switch tube from the primary coil of the inverter isolation transformer to the power supply and the diode to the ground, forming a reliable primary coil voltage embedding; the power switch tube is synchronously turned on and off, which is consistent with the single-tube working efficiency; and the first power switch tube Q1 and the second power switch tube Q2 are based on the intervention of the first voltage embedding diode D3 and the second voltage embedding diode D4, and the third power switch tube Q3 and the fourth power switch tube Q4 are based on the intervention of the third voltage embedding diode D7 and the fourth voltage embedding diode D8, and the voltage level does not exceed the DC power supply voltage, which is in an absolutely safe working environment. In addition, the first voltage embedding diode D3, the second voltage embedding diode D4, the third voltage embedding diode D7 and the fourth voltage embedding diode D8 also guide the potential of the primary coil induced in the secondary coil to the power supply end, so that the energy utilization rate is improved, and the overall conversion efficiency is greatly improved compared with the single-tube mode. Moreover, the driving waveform of the dual system adopted by the present invention is twice the driving waveform of the dual single-tube voltage-embedded diode inverter circuit, especially the driving waveform of the dual system composed of the first dual single-tube forward inverter circuit unit 21 and the second dual single-tube forward inverter circuit unit 22 is forced to be staggered, so that the two systems alternately work and are in an excitation state. The essence of the alternating work of the two systems is that the first high-frequency transformer T1 and the second high-frequency transformer T2 alternately input and output DC voltage, and the secondary voltage phase sequence is staggered. In addition, a parallel rectification mode is adopted and the frequency is superimposed to achieve the effect of voltage superposition.

[0035] Preferably, the first dual single-tube forward inverter circuit unit also includes a first current limiting resistor R1 and a second current limiting resistor R2, the first current limiting resistor R1 is arranged to be connected between the base of the first power switch tube and the first end of the isolation driving circuit, and the second current limiting resistor R2 is arranged to be connected between the base of the second power switch tube and the third end of the isolation driving circuit; the second dual single-tube forward inverter circuit unit also includes a third current limiting resistor R3 and a fourth current limiting resistor R4, the third current limiting resistor R3 is arranged to be connected between the base of the third power switch tube and the fifth end of the isolation driving circuit, and the fourth current limiting resistor R4 is arranged to be connected between the base of the fourth power switch tube and the seventh end of the isolation driving circuit.

[0036] Preferably, the DC input unit 1 includes an AC voltage input terminal, a rectifier circuit BG1, a first DC input processing unit and a second DC input processing unit. The first DC input processing unit 11 includes a first capacitor C1, a first electrolytic capacitor E1, a second electrolytic capacitor E2, a first voltage-equalizing and discharge resistor R5 and a second voltage-equalizing and discharge resistor R6. The second DC input processing unit 12 includes a second capacitor C2, a third electrolytic capacitor E3, a fourth electrolytic capacitor E4, a third voltage-equalizing and discharge resistor R7 and a fourth voltage-equalizing and discharge resistor R8. The AC voltage input terminal is connected to the rectifier circuit BG1, and the positive terminal of the rectifier circuit BG1 is connected in parallel to one end of the first capacitor C1, the positive electrode of the first electrolytic capacitor E1 and one end of the first voltage-equalizing and discharge resistor R5, the second capacitor E3, and the positive electrode of the first electrolytic capacitor E4. The negative terminal of the rectifier circuit BG1 is grounded and connected in parallel to the other end of the first capacitor C1, the negative electrode of the second electrolytic capacitor E2, one end of the second voltage-equalizing and discharge resistor R6, the other end of the second capacitor C2, the negative electrode of the fourth electrolytic capacitor E4 and one end of the fourth voltage-equalizing and discharge resistor R8, the negative electrode of the first electrolytic capacitor E1, the positive electrode of the second electrolytic capacitor E2, the other end of the first voltage-equalizing and discharge resistor R5 and the other end of the second voltage-equalizing and discharge resistor R6 are connected, the negative electrode of the third electrolytic capacitor E3, the positive electrode of the fourth electrolytic capacitor E4, the other end of the third voltage-equalizing and discharge resistor R7 and the other end of the fourth voltage-equalizing and discharge resistor R8 are connected. The voltage of the AC voltage input terminal can be 300-450VAC, which is used for power input. The rectifier circuit BG1 is used to convert AC into DC. The first capacitor C1 and the second capacitor C2 are high-frequency energy storage capacitors. The first electrolytic capacitor E1, the second electrolytic capacitor E2, the third electrolytic capacitor E3 and the fourth electrolytic capacitor E4 are all low-frequency energy storage electrolytic capacitors. The first voltage-equalizing and discharge resistor R5, the second voltage-equalizing and discharge resistor R6, the third voltage-equalizing and discharge resistor R7 and the fourth voltage-equalizing and discharge resistor R8 are voltage-equalizing and discharge power resistors.

[0037] Preferably, the DC output unit 5 includes a first DC output processing unit 51, a second DC output processing unit 52, an inductor L1 and a voltage output terminal, the first DC output processing unit 51 includes a first absorption current limiting resistor R9, a second absorption current limiting resistor R10, a first absorption capacitor C3, a second absorption capacitor C4, a first high-frequency rectifier fast recovery diode D9 and a first freewheeling fast recovery diode D10, the second DC output processing unit 52 includes a third absorption current limiting resistor R11, a fourth absorption current limiting resistor R12, a third absorption capacitor C5, a fourth absorption capacitor C6, a second high-frequency rectifier fast recovery diode D9 and a first freewheeling fast recovery diode D10. A rectifier fast recovery diode D11 and a second freewheeling fast recovery diode D12, the opposite-name end of the secondary coil of the high-frequency transformer T1 is connected in parallel to one end of the second absorption current limiting resistor R10, the anode of the first freewheeling fast recovery diode D10 and the one end of the inductor, the other end of the second absorption current limiting resistor R10 is connected to one end of the second absorption capacitor C4, the same-name end of the secondary coil of the first high-frequency transformer T1 is connected in parallel to one end of the first absorption current limiting resistor R9, the anode of the first high-frequency rectifier fast recovery diode D9, and the second high-frequency transformer T2 The same-name end of the secondary coil of the high-frequency transformer T2 is connected in parallel to one end of the third absorption current-limiting resistor R11 and the anode of the second high-frequency rectifier fast recovery diode D11, the opposite-name end of the secondary coil of the high-frequency transformer T2 is connected in parallel to one end of the fourth absorption current-limiting resistor R12, the anode of the second freewheeling fast recovery diode D12 and the one end of the inductor, the other end of the fourth absorption current-limiting resistor R12 is connected to one end of the fourth absorption capacitor C6, the other end of the first absorption capacitor C3 is connected in parallel to the other end of the second absorption capacitor C4 and the other end of the third absorption capacitor C5. One end is connected to the other end of the fourth absorption capacitor C6, the cathode of the first high-frequency rectifier fast recovery diode D9, the cathode of the first freewheeling fast recovery diode D10, the cathode of the second high-frequency rectifier fast recovery diode D11, the cathode of the second freewheeling fast recovery diode D12, one end of the load maintenance resistor RL and the positive end of the voltage output end. The first high-frequency rectifier fast recovery diode D9, the first freewheeling fast recovery diode D10, the second high-frequency rectifier fast recovery diode D11 and the second freewheeling fast recovery diode D12 are fast recovery diodes, which play a role of secondary high-frequency rectification. The inductor L1 is a DC filter reactor composed of a high-frequency magnetic ring. The voltage output end is used to connect the welding gun and the base material. The output voltage of the voltage output end can be controlled at 44VDC.

[0038] Preferably, the DC output unit 5 further comprises a load resistor RL, one end of which is connected to the cathode of the fifth voltage clamping diode D5, and the other end of which is connected to the other end of the inductor L1. The load resistor RL plays a role in no-load maintenance.

[0039] A device provided with a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine, wherein the device provided with a dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine is any of the above-mentioned dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuits for a welding machine.

[0040] The present invention adopts dual-single-tube technology and combines dual-embedded diodes to solve the drawback of the VMOS tube's voltage resistance level limitation, and realizes the addition of a dual-single-tube forward dual-system inverter circuit unit 2 on the technical basis of the single-tube excitation mode circuit structure, and the switch tube from the primary coil of the inverter isolation transformer to the power supply and the diode to the ground form a reliable primary coil voltage embedding; the power switch tube is turned on and off synchronously, which is consistent with the working efficiency of the single tube; and the first power switch tube Q1 and the second power switch tube Q2 are based on the intervention of the first voltage embedding diode D3 and the second voltage embedding diode D4, and the voltage level does not exceed the DC power supply voltage, and is in an absolutely safe working environment; in addition, the first voltage embedding diode D3 and the second voltage embedding diode D4 also guide the potential of the primary coil induced in the secondary coil to the power supply end, so the energy utilization rate is improved, and the overall conversion efficiency is greatly improved compared with the single-tube mode.

[0041] The first power switch tube Q1 and the second power switch tube Q2 of the present invention are turned on and off synchronously. Compared with the bridge type and push-pull type working modes, no dead time setting is required, and the possibility of damage caused by the simultaneous conduction of the two tubes is eliminated, which is very safe.

[0042] In the prior art, there is always a certain distance between the installation layout of the two power switch tubes and the driving signal circuit, which will be affected by the line inductive parameters due to high-frequency factors, resulting in inconsistency in the conduction or shutdown of the two tubes; the bridge and push-pull working modes will reduce the maximum pulse width in order to design a fault tolerance margin for this unfavorable factor, thereby limiting the maximum conversion efficiency. The structure of the dual single tube plus embedded diode of the present invention does not need such concerns, and the structure of the dual single tube plus embedded diode of the present invention can be based on the voltage embedded diode intervention design and the low requirements for pulse width accuracy of the upper and lower tubes, so that two or even multiple high-frequency single tube IGBTs can be connected in parallel to still form a sufficiently large current capacity, thereby achieving sufficient power conversion capacity. The present invention uses IGBT single tubes in parallel to achieve a sufficiently high inverter frequency, a sufficiently large inverter output power, and a safety guarantee sufficient to meet the harsh environment of the electric welding machine.

[0043] The improvement of the inverter frequency of the present invention reduces the volume of electromagnetic devices and reduces costs; on the other hand, it improves the quality of the welding process, and the improvement of control accuracy brings about electrical requirements that are more suitable for high-speed welding and high reliability.

[0044] In the dual-single-tube positive pole excitation plus diode embedded inverter circuit adopted by the present invention, the working mode of the single-tube IGBT is completely consistent, the power tube has sufficient opening and stopping time length, and the working timing is all the same; the small errors formed between each other will be offset based on the synchronous switch conversion, so as not to cause the disadvantages caused by parallel connection. It is precisely based on the characteristics of the circuit structure that the current parallel superposition can be easily realized, so that the dual-single-tube positive pole excitation plus diode embedded dual inverter circuit adopted by the present invention has a very obvious advantage in constructing a new high-frequency inverter welding machine. The present invention realizes the improvement of the inverter frequency, which not only reduces the volume and cost of the structure, but also improves the control accuracy to achieve accurate and effective high-speed welding; the present invention realizes the arbitrary improvement of the output current; the single-tube IGBT can realize arbitrary parallel superposition, that is, it creates any composition of output current capacity, forming a reasonable layout of the product structure, and greatly improving the product cost performance and reliability.

[0045] In the prior art, when installing and fixing a single IGBT tube, insulating cloth is used to install the IGBT with electrode plate close to the heat sink, or even through certain electrical treatments, the heat sink is divided so that the IGBT tube can be directly mounted on the heat sink. However, the creepage distance and installation tension consistency cannot be reliably guaranteed. The PCB insulated aluminum substrate design and the finished IGBT single tube are subjected to a secondary vacuum welding process, which has more advantages than the aforementioned single-tube IGBT finished product fastening installation, but requires close coordination of many links such as the overall layout. Therefore, the products implemented by this process cannot become a mass-produced civilian product option. The present invention overcomes these shortcomings and organizes the development of such Figure 2 The new packaging module forms a new IGBT wafer packaging modular structure. Figure 2As shown, its reliability, cost performance and production and maintenance convenience far exceed the existing IGBT products, where Q1 and Q2 are two independently packaged IGBTs. The control signal of Q1 is input by pins 7 and 10, and the control signal of Q2 is input by pins 13 and 16, realizing the effect of voltage clamping. The present invention can cover all models from 120A to 1600A, and can become a new circuit form that completely replaces the existing bridge electrical circuit structure. In 120A-400A models: adopt single system mode; parallel package modules are connected from 1 to 3 in parallel; isolation transformers are wound with high-frequency iron powder core rings with open air gaps, and magnetic ring specifications of 633530 to 1026530 can be met. In 500A-1000A models: adopt dual system mode; parallel package modules are connected from 3 to 6 in parallel; isolation transformers are wound with high-frequency iron powder core rings with open air gaps, and magnetic ring specifications of 1026530 to 1026035 magnetic cores can be met in parallel. For 1000A---1600A models: dual system mode is adopted; the number of parallel packaged modules increases from 6 to 8; the isolation transformer is wound with a high-frequency iron powder core ring with an open air gap, and the magnetic ring specification can be 1026035 to 1308035 magnetic cores in parallel.

[0046] During the welding process, the splash of solvent will cause many problems such as solder loss, poor welding forming, and welding material damage. In particular, this defect causes huge process risks for semi-automatic welding and automatic welding. The present invention has adaptive arc self-adjusting electrical capabilities in welding, which increases the inverter frequency from 20KHz to 40KHz, or even 100KHz, which is equivalent to increasing the number of control implementations per second from 10,000 times to 40,000 to 50,000 times; calculated according to the droplet transition time during normal welding, at 20KHz, each droplet has about 25 inverter frequency pulses; at 80KHz, each droplet has about 100 inverter frequency pulses. When the frequency rises to 80KHz, the necking period of each droplet is about 24 inverter frequency pulses, and low spatter control can be achieved more accurately through technical means. The most important thing is that it is easier to achieve low spatter control in the actual welding process, which means that more welding specifications can be achieved. Such as Figure 3 and Figure 4As shown, T1 is the arcing time, T2 is the short circuit time, t3 is the voltage recovery time, Imin is the minimum current, Imax is the maximum current, Ia is the average welding current, and Ua is the average arc voltage. According to the waveform control theory, the best means to achieve short-circuit transition and low spatter is during the necking period of the droplet transition. Simply dividing the time, the necking period accounts for about 20% of the droplet transition time. At 20KHz, each droplet necking period is about 6 inverter frequency pulses. To achieve low spatter control, it is necessary to measure and correct the number of pulses for each droplet and obtain data, and then use this number as the total number to calculate the amplitude compression of the pulses from which to which pulses. The essence is to reduce the output power, reduce the electromagnetic contraction force during necking, and rely more on surface tension transition. The present invention is based on the increase of frequency, that is, it multiplies the control frequency density of droplet transition, which makes it easier to achieve precise welding control. Precision welding can also be improved to the point where the control is fully and effectively reflected in the weld formation, thereby greatly reducing labor costs and welding quality. During manual welding, high-quality semi-automatic welding (CO2 welding) can be achieved with simple manipulation. When matching the high-speed welding and small current precision welding of robot automatic welding, the characteristics of the robot system or some special welding machine mechanisms can be fully utilized based on this adaptability and control accuracy effectiveness.

[0047] When automatic welding realizes automatic wire feeding, submerged arc welding and gas shielded welding belong to this category. Figures 5 to 8As shown in the figure, b is the weld melting width, t is the weld melting depth, h is the weld reinforcement height, At is the cross-sectional area of ​​the filler metal in the weld, and Am is the cross-sectional area of ​​the molten metal of the base material in the weld. The external characteristic curve of the power supply and the static external characteristic of the arc determine the welding current and welding voltage during submerged arc welding. In the actual welding process, both the external characteristic curve of the power supply and the static external characteristic of the arc will fluctuate due to external interference, so that the welding current and welding voltage will also change during the actual welding process. Among various interference factors, arc length interference is the most prominent. The self-regulating system of the arc welding power supply can eliminate or weaken the interference effect of arc length change by detecting the arc length change, maintain stable arc burning during welding, and control the weld penetration and width within the allowable range. Correspondingly, CO2 welding is equivalent to fine wire submerged arc welding. Parameter adjustment method of arc voltage feedback wire feeding system: Adjusting the external characteristic of the power supply is mainly to adjust the welding current, while adjusting the given voltage of the wire feeding motor, that is, adjusting the wire feeding speed is to adjust the arc voltage. The adjustment range of the welding voltage is determined by the adjustment range of the external characteristics of the power supply, while the adjustment range of the wire feeding speed determines the adjustment range of the arc voltage. Take the CO2 welding wire feeding adjustment as an example: when interference occurs, the arc length changes, that is, the arc voltage changes. The arc voltage is fed back to the control system to cause the wire feeding speed to change. The wire feeding speed is self-adjusted to restore the arc length to a normal value, and the whole process is normal. The increase in the inverter frequency of the present invention can more accurately and timely increase the arc length self-adjustment speed by multiples, and the effect achieved is that stable welding can be achieved even if the welding torch is not very stable or the welding torch moves fast.

[0048] The present invention adopts a dual-system driving waveform that is twice the driving waveform of the dual-single-tube voltage-embedded diode inverter circuit, especially the driving waveform of the dual system composed of the first dual-single-tube forward inverter circuit unit and the second dual-single-tube forward inverter circuit unit is forced to be staggered, and the effect achieved is that the two systems work alternately in the excitation state. The essence of the alternating operation of the two systems is that the first high-frequency transformer and the second high-frequency transformer alternately input and output AC voltage, the secondary voltage phase sequence is staggered, and the parallel rectification mode is adopted, and the frequency is superimposed, so as to achieve the effect of increasing the frequency and power by voltage superposition, and then obtain the DC voltage output through rectification and filtering. The present invention makes it possible to significantly improve the welding effect and welding quality, and is a new technology product that can fully match the automated intelligent welding. It can become a new technology model leading a new generation of inverter welding power supplies.

[0049] The invention adopts a dual-single-tube positive pole excitation plus a diode embedded inverter circuit main structure inverter welding machine invention can achieve a new circuit structure form from 120 to 500A, which can completely replace the existing bridge electrical circuit structure. The invention adopts the latest power and electrical technology such as the overall electrical structure, the main isolation transformer adopted by advanced technology, and the multiple high-frequency IGBT wafers parallel packaging products using modular insulation heat dissipation bottom plate. It is a new technology product with many innovative points. The invention fully meets the requirements of high technology, new innovation, green energy saving and environmental protection.

[0050] The present invention has been described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. Therefore, some details in the embodiments shall not constitute a limitation of the present invention, and the present invention shall be protected by the scope defined by the attached claims.

Claims

1. A dual-single-tube voltage-clamped diode inverter dual-system high-frequency circuit for welding machine, characterized in that: The dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine comprises a DC input unit, a dual-single-tube forward dual-system inverter circuit unit, a DC output unit, a PWM circuit and an isolation driving circuit. The dual-single-tube forward dual-system inverter circuit unit comprises a first dual-single-tube forward inverter circuit unit and a second dual-single-tube forward inverter circuit unit. The first dual-single-tube forward inverter circuit unit comprises a first voltage-embedded diode, a second voltage-embedded diode, a first anti-parallel diode, a second anti-parallel diode, a first power switch tube, a second power switch tube and a first high-frequency transformer. The second dual-single-tube forward inverter circuit unit comprises a third voltage-embedded diode, a fourth voltage-embedded diode, a third anti-parallel diode, a fourth anti-parallel diode, a third power switch tube, a fourth power switch tube and a second high-frequency transformer. The same-name end and the opposite-name end of the secondary coil of the first high-frequency transformer are respectively connected to the positive and negative poles of the DC output unit. The same-name end and the opposite-name end of the secondary coil of the second high-frequency transformer are respectively connected to the positive and negative poles of the DC output unit. The isolation driving circuit is connected to the PWM circuit, wherein: The collector of the first power switch tube is connected in parallel to the positive electrode of the DC input unit, the cathode of the first voltage clamping diode and the cathode of the first anti-parallel diode, the base of the first power switch tube is connected to the first end of the isolation driving circuit, the emitter of the first power switch tube is connected in parallel to the cathode of the second voltage clamping diode, the anode of the first anti-parallel diode, the same-name end of the primary coil of the high-frequency transformer and the second end of the isolation driving circuit, the collector of the second power switch tube is connected in parallel to the anode of the first voltage clamping diode, the cathode of the second anti-parallel diode and the opposite-name end of the primary coil of the first high-frequency transformer, the base of the second power switch tube is connected to the third end of the isolation driving circuit, and the emitter of the second power switch tube is connected in parallel to the anode of the second voltage clamping diode, the anode of the second anti-parallel diode, the fourth end of the isolation driving circuit and the negative electrode of the DC input unit; The collector of the third power switch tube is connected in parallel to the positive electrode of the DC input unit, the cathode of the third voltage clamping diode and the cathode of the third anti-parallel diode, the base of the third power switch tube is connected to the fifth end of the isolation driving circuit, the emitter of the third power switch tube is connected in parallel to the cathode of the fourth voltage clamping diode, the anode of the third anti-parallel diode, the same-name end of the primary coil of the second high-frequency transformer and the sixth end of the isolation driving circuit, the collector of the fourth power switch tube is connected in parallel to the anode of the third voltage clamping diode, the cathode of the fourth anti-parallel diode and the opposite-name end of the primary coil of the second high-frequency transformer, the base of the fourth power switch tube is connected to the seventh end of the isolation driving circuit, and the emitter of the fourth power switch tube is connected in parallel to the positive electrode of the fourth voltage clamping diode, the anode of the fourth anti-parallel diode, the eighth end of the isolation driving circuit and the negative electrode of the DC input unit.

2. The dual single-tube voltage clamping diode inverter dual-system high-frequency circuit for welding machine according to claim 1 is characterized in that: The first dual single-tube forward inverter circuit unit also includes a first current limiting resistor and a second current limiting resistor, the first current limiting resistor is arranged to be connected between the base of the first power switch tube and the first end of the isolation driving circuit, and the second current limiting resistor is arranged to be connected between the base of the second power switch tube and the third end of the isolation driving circuit; the second dual single-tube forward inverter circuit unit also includes a third current limiting resistor and a fourth current limiting resistor, the third current limiting resistor is arranged to be connected between the base of the third power switch tube and the fifth end of the isolation driving circuit, and the fourth current limiting resistor is arranged to be connected between the base of the fourth power switch tube and the seventh end of the isolation driving circuit.

3. The dual single-tube voltage clamping diode inverter dual-system high-frequency circuit for welding machine according to claim 1 is characterized in that: The DC input unit includes an AC voltage input terminal, a rectifier circuit, a first DC input processing unit and a second DC input processing unit. The first DC input processing unit includes a first capacitor, a first electrolytic capacitor, a second electrolytic capacitor, a first voltage balancing and discharge resistor and a second voltage balancing and discharge resistor. The second DC input processing unit includes a second capacitor, a third electrolytic capacitor, a fourth electrolytic capacitor, a third voltage balancing and discharge resistor and a fourth voltage balancing and discharge resistor. The AC voltage input terminal is connected to the rectifier circuit, and the positive terminal of the rectifier circuit is connected in parallel to one end of the first capacitor, the positive electrode of the first electrolytic capacitor, one end of the first voltage balancing and discharge resistor, and one end of the second capacitor. , the positive electrode of the third electrolytic capacitor and one end of the third equalizing and discharge resistor, the negative end of the rectifier circuit is grounded and connected in parallel to the other end of the first capacitor, the negative electrode of the second electrolytic capacitor, one end of the second equalizing and discharge resistor, the other end of the second capacitor, the negative electrode of the fourth electrolytic capacitor and one end of the fourth equalizing and discharge resistor, the negative electrode of the first electrolytic capacitor, the positive electrode of the second electrolytic capacitor, the other end of the first equalizing and discharge resistor and the other end of the second equalizing and discharge resistor are connected, the negative electrode of the third electrolytic capacitor, the positive electrode of the fourth electrolytic capacitor, the other end of the third equalizing and discharge resistor and the other end of the fourth equalizing and discharge resistor are connected.

4. The dual single-tube voltage clamping diode inverter dual-system high-frequency circuit for welding machine according to claim 1 is characterized in that: The DC output unit includes a first DC output processing unit, a second DC output processing unit, an inductor, a load maintaining resistor and a voltage output terminal. The first DC output processing unit includes a first absorption current limiting resistor, a second absorption current limiting resistor, a first absorption capacitor, a second absorption capacitor, a first high-frequency rectifier fast recovery diode and a first freewheeling fast recovery diode. The second DC output processing unit includes a third absorption current limiting resistor, a fourth absorption current limiting resistor, a third absorption capacitor, a fourth absorption capacitor, a second high-frequency rectifier fast recovery diode and a second freewheeling fast recovery diode. The same-name end of the secondary coil of the second high-frequency transformer is connected in parallel to one end of the third absorption current limiting resistor and the anode of the second high-frequency rectifier fast recovery diode. The same-name end of the secondary coil of the first high-frequency transformer is connected in parallel to one end of the first absorption current limiting resistor and the anode of the first high-frequency rectifier fast recovery diode. The opposite-name end of the secondary coil of the high-frequency transformer is connected in parallel to the second absorption current limiting resistor. One end of the first absorption capacitor, the anode of the first freewheeling fast recovery diode and the one end of the inductor, the other end of the second absorption current limiting resistor is connected to one end of the second absorption capacitor, the opposite end of the secondary coil of the high-frequency transformer is connected in parallel to one end of the fourth absorption current limiting resistor, the anode of the second freewheeling fast recovery diode and the one end of the inductor, the other end of the fourth absorption current limiting resistor is connected to one end of the fourth absorption capacitor, the other end of the first absorption capacitor is connected in parallel to the other end of the second absorption capacitor, the other end of the third absorption capacitor, the other end of the fourth absorption capacitor, the cathode of the first high-frequency rectifier fast recovery diode, the cathode of the first freewheeling fast recovery diode, the cathode of the second high-frequency rectifier fast recovery diode, the cathode of the second freewheeling fast recovery diode, one end of the load maintenance resistor and the positive end of the voltage output end are connected, and the other end of the inductor is connected to the other end of the load maintenance resistor and the negative end connected to the voltage output end.

5. The dual single-tube voltage clamping diode inverter dual-system high-frequency circuit for welding machine according to claim 4 is characterized in that: The DC output unit also includes an output load resistor for maintaining a no-load state, one end of the load resistor is connected to the cathodes of the first and second high-frequency rectifier diodes, and the other end of the load resistor is connected to the other end of the inductor.

6. A device provided with a dual-single-tube voltage clamping diode inverter dual-system high-frequency circuit for a welding machine, characterized in that: The dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine is the dual-single-tube voltage-embedded diode inverter dual-system high-frequency circuit for a welding machine as claimed in any one of claims 1 to 5.

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