High-frequency pulse composite direct current precise micro-TIG arc spot welding power supply and spot welding method

Abstract

The application discloses a high-frequency pulse compound direct-current precise micro-TIG arc spot welding power supply and a spot welding method, wherein the power supply comprises a first direct-current power supply, a second direct-current power supply, a high-frequency switching circuit and a control system; the second direct-current power supply is connected with the high-frequency switching circuit, and a pulse current output by the switching circuit is superimposed with direct current output by the first direct-current power supply to provide the arc load; and the control system comprises a DSP controller, a driving circuit, a sampling circuit, a fault detection circuit and the like. The power supply can provide high-frequency pulse current for the micro-TIG arc, improve the transient current density of the micro-TIG arc, and greatly reduce the occurrence of defects such as micro-TIG arc anode spot jumping and easy arc breaking, so that the arc current of stable welding can be reduced to 2A, the stability of the micro-TIG arc and the quality of the spot welding joint are obviously improved, and the application range of the micro-TIG arc welding process is expanded. The application can be widely applied to arc welding power supply equipment.

Description

Technical Field

[0001] This invention relates to arc welding power supply equipment, and more particularly to a high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply and spot welding method. Background Technology

[0002] With the rapid development of precision and high quality in electronic products, higher requirements have been placed on the quality and performance of various electronic components and their connections. Improving welding precision and stability has become the key to the successful manufacturing of some micro-device products.

[0003] Micro-TIG arc welding involves low current and low heat generation, and its tungsten electrode conditions and external electric field are complex. Cathode spots may appear on the side of the electrode tip, exhibiting irregular climbing or rotation. On the anode surface, even small amounts of impurities can cause intermittent arc jumping, with arc instability becoming more pronounced below 5A current. This arc instability significantly impacts the macroscopic morphology and performance quality of precision components, thus reducing the adaptability and application range of this welding method. Summary of the Invention

[0004] In order to at least partially solve one of the technical problems existing in the prior art, the purpose of this invention is to provide a high-frequency pulse composite DC precision micro TIG arc spot welding power supply and spot welding method.

[0005] The technical solution adopted in this invention is:

[0006] A high-frequency pulsed composite DC precision micro TIG arc spot welding power supply includes a main circuit consisting of a first DC power supply, a second DC power supply and a high-frequency switching circuit, and a control system for controlling the main circuit. The control system includes a DSP controller, a PWM drive circuit, a current sampling circuit, a fault detection circuit and a data communication circuit.

[0007] Both the first DC power supply and the second DC power supply include a three-phase rectifier, a capacitor filter, an inverter bridge, a high-frequency transformer, a secondary rectifier, and an output filter circuit connected in sequence.

[0008] The high-frequency switching circuit is connected to the output terminal of the second DC power supply. After being modulated by the MOS field-effect transistor of the switching circuit, a high-frequency pulse current is obtained. The high-frequency pulse current is superimposed and combined with the DC current output by the first DC power supply and then provided to the arc load.

[0009] The DSP controller is used to control the entire welding power supply, and the PWM drive circuit, current sampling circuit and fault detection circuit are connected to the DSP controller.

[0010] Among them, the open-circuit voltage is relatively high, reaching over 100V, to match the physical characteristics of the high field strength of the micro-TIG arc.

[0011] Furthermore, the high-frequency switching circuit is composed of a MOS field-effect transistor and its RC snubber circuit. The drain D of the MOS field-effect transistor is connected to the positive terminal of the second DC power supply, and the source S of the MOS field-effect transistor is connected to the negative terminal of the second DC power supply.

[0012] In the high-frequency switching circuit, when the MOSFET is turned on, the current output from the second DC power supply flows directly from the positive terminal back to the negative terminal through the MOSFET; when the MOSFET is turned off, the current from the second DC power supply flows from the positive terminal back to the negative terminal through the arc load. Therefore, by controlling the on and off frequency and duty cycle of the MOSFET, the frequency and duty cycle of the pulse current output to the arc load are modulated. The amplitude of the pulse current is equal to the current output by the second DC power supply.

[0013] Furthermore, the current output from the second DC power supply, modulated by a high-frequency switching circuit, is superimposed and combined with the current output from the first DC power supply to supply the arc load.

[0014] The base value of the high-frequency pulse current supplied to the arc load by the superimposed composite is equal to the current value output by the first DC power supply, and the pulse amplitude of the high-frequency pulse current is equal to the current value output by the switching circuit.

[0015] Furthermore, the DSP controller is connected to the input terminal of the PWM drive circuit, and controls the on and off of the corresponding MOS field-effect transistor through the output signal of the drive circuit;

[0016] The PWM driving circuit includes a first driving circuit, a second driving circuit, and a third driving circuit; wherein the first driving circuit is connected to the MOS field-effect transistor of the inverter bridge of the first DC power supply, the second driving circuit is connected to the MOS field-effect transistor of the inverter bridge of the second DC power supply, and the third driving circuit is connected to the MOS field-effect transistor of the high-frequency switching circuit.

[0017] The output terminal of the driving circuit is connected to the gate (G) and source (S) of the MOS field-effect transistor.

[0018] Furthermore, the current sampling circuit includes a first current sampling circuit and a second current sampling circuit; the first current sampling circuit collects the filtered current output from the first DC power supply to obtain a first feedback current signal; the second current sampling circuit collects the filtered current output from the second DC power supply to obtain a second feedback current signal.

[0019] Based on the first feedback current signal, the DSP controller outputs a first PWM signal to the first drive circuit; the first PWM signal is used to adjust the output current value of the first DC power supply.

[0020] The step of outputting the first PWM signal according to the first feedback current signal includes: obtaining a first deviation between the first feedback current signal and the corresponding value of the preset first current, and then using PI control to adjust the duty cycle according to the first deviation to obtain the first PWM signal;

[0021] Based on the second feedback current signal, the DSP controller outputs a second PWM signal to the second drive circuit; the second PWM signal is used to adjust the output current value of the second DC power supply.

[0022] The step of outputting the second PWM signal based on the second feedback current signal includes: obtaining a second deviation between the second feedback current signal and the corresponding value of the preset second current, and then using PI control to adjust the duty cycle according to the second deviation to obtain the second PWM signal.

[0023] Furthermore, the high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply also includes a human-machine interaction system connected to the DSP controller;

[0024] The human-computer interaction system includes a keypad and an LCD screen.

[0025] The keypad is used to set the first current output by the first DC power supply, the welding time, the second current output by the second DC power supply, and the frequency and duty cycle of the high-frequency pulse current at each stage.

[0026] The LCD screen is used to display real-time input parameter settings, real-time welding current, and fault type.

[0027] Furthermore, the closed-loop feedback loop of the current sampling circuit is implemented using a digital PID algorithm.

[0028] Furthermore, the fault detection circuit includes an over-temperature detection circuit and an over-current detection circuit.

[0029] Another technical solution adopted in this invention is:

[0030] A high-frequency pulsed composite DC precision micro-TIG arc spot welding method is applied to the high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply mentioned above, including a high-frequency pulsed current waveform, a base value arc-maintaining stage, a base value gradual rise stage, a main welding stage, a base value gradual fall stage, and a base value arc-terminating stage.

[0031] The base value arc-maintaining stage: after the arc is detected to be successfully ignited, a high-frequency pulse current is superimposed, and the base value current output by the first DC power supply is adjusted to reduce the arc current to maintain a stable arc combustion state.

[0032] The base value gradual increase stage: After the electric arc is stably burning and the preheating time is set, the base value current output by the first DC power supply is gradually increased to the base value current value set in the main welding stage within a set time.

[0033] The main welding stage: During the welding process, the base current output by the first DC power supply is maintained at the set welding current value;

[0034] The base value descent phase: When the welding process ends, the base value current output by the first DC power supply is gradually reduced to the set arc-ending current value within a set time.

[0035] The base value arc-ending stage: for a set time period, the base value current output by the first DC power supply is maintained at the set arc-ending current value, and then reduced to zero.

[0036] The high-frequency pulse current waveform: After successful arc ignition, the high-frequency pulse current is superimposed on the base current output by the first DC power supply until the base current drops to zero.

[0037] Furthermore, the process includes an early gas supply stage before the baseline arc stage and a delayed gas shut-off stage after the baseline arc termination stage.

[0038] The beneficial effects of this invention are as follows: Based on the current change of high-frequency pulses, the transient electron density of the microTIG arc is increased, which greatly reduces the occurrence of defects such as anode spot jumping and easy arc breakage in the microTIG arc, and improves the continuity of the arc. The electromagnetic effect of the high-frequency pulse current increases the straightness of the microTIG arc. Therefore, the welding power source and welding method provided by this invention greatly improve the stability of the microTIG arc, especially the arc stability below 5A current, resulting in better welding quality and expanding the application range of microTIG arc welding technology. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following description is provided with accompanying drawings of the relevant technical solutions in the embodiments of the present invention or the prior art. It should be understood that the accompanying drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply in one embodiment.

[0041] Figure 2 This is a schematic diagram of the main circuit of a high-frequency pulse composite DC precision micro TIG arc spot welding power supply in one embodiment;

[0042] Figure 3This is a schematic diagram of the process of outputting the base current in one embodiment;

[0043] Figure 4 This is a schematic diagram of the process of outputting peak current in one embodiment;

[0044] Figure 5 The current waveform diagram for high-frequency pulsed DC precision micro-TIG arc spot welding in one embodiment is shown.

[0045] Figure 6 A schematic diagram of the current waveform for high-frequency pulsed DC precision micro-TIG arc spot welding.

[0046] Figure 7 This is a schematic diagram of the arc morphology during high-frequency pulsed composite DC precision micro-TIG arc spot welding 3A in one embodiment.

[0047] Figure 8 This is a schematic diagram of the arc morphology during high-frequency pulsed composite DC precision micro-TIG arc spot welding 2A in one embodiment. Detailed Implementation

[0048] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The step numbers in the following embodiments are set only for ease of explanation, and there is no limitation on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0049] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0050] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0051] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0052] like Figure 1 As shown, this embodiment provides a high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply. This power supply can provide high-frequency pulsed current to the micro-TIG arc, increasing the transient current density of the micro-TIG arc, thereby greatly reducing defects such as anode spot jump and easy arc breakage in the micro-TIG arc. It can reduce the arc current for stable welding to 2A, significantly improving the stability of the micro-TIG arc and the quality of the spot weld joint, and expanding the application range of the micro-TIG arc welding process. The power supply in this embodiment specifically includes:

[0053] The system comprises a first DC power supply, a second DC power supply, a high-frequency switching circuit, and a control system for controlling the main circuit.

[0054] The first DC power supply, the second DC power supply, and the high-frequency switching circuit constitute the main power supply circuit of the present invention.

[0055] Both the first DC power supply and the second DC power supply include a three-phase rectifier, a capacitor filter, a full-bridge inverter, a high-frequency transformer, a secondary rectifier, and an output filter circuit connected in sequence.

[0056] The inverter bridge output of the first DC power supply provides AC voltage to the high-frequency arc ignition circuit.

[0057] Once the DSP controller determines that the arc ignition is successful, it turns on the second DC power supply inverter bridge and outputs the second DC power.

[0058] The high-frequency switching circuit is connected to the output terminal of the second DC power supply, and obtains a high-frequency pulse current after being modulated by the switching circuit MOS transistor.

[0059] The current output by the first DC power supply is the base value of the arc current.

[0060] The current output by the second DC power supply is equal to the amplitude of the pulse current.

[0061] The high-frequency pulse amplitude is superimposed and combined with the DC power output from the first DC power supply to provide power to the arc load.

[0062] The peak value of the high-frequency pulse current is the sum of the current value output by the first DC power supply and the amplitude of the high-frequency pulse.

[0063] The high-frequency pulse micro-TIG welding power supply outputs an open-circuit voltage of 108V to match the large voltage drop of the micro-TIG arc field.

[0064] The control system includes a DSP controller, a PWM drive circuit, a current sampling circuit, a fault detection circuit, and a data communication circuit.

[0065] The PWM drive circuit has three channels, all of which are connected to the DSP controller.

[0066] Furthermore, the output of the PWM drive circuit is connected to the gate (G) and source (S) of the MOS field-effect transistor, and this signal controls the conduction and turn-off of the field-effect transistor.

[0067] The current sampling circuit has two paths, both of which are connected to the DSP controller.

[0068] Furthermore, in one embodiment, such as Figure 2 The figure shows a schematic diagram of the main circuit of a high-frequency pulse composite DC precision micro TIG arc spot welding power supply.

[0069] The first PWM drive signal controls the turn-on and turn-off of four MOS field-effect transistors Q1, Q2, Q3 and Q4 on the first DC power supply inverter bridge, with Q1 and Q4 being turned on simultaneously and Q2 and Q3 being turned on simultaneously.

[0070] The second PWM drive signal controls the on / off state of four MOSFETs Q5, Q6, Q7, and Q8 on the second DC power supply inverter bridge, with Q5 and Q8 being on simultaneously and Q6 and Q7 being on simultaneously.

[0071] The MOSFETs on the first and second DC power inverter bridges have a switching frequency of 100kHz, a control time accuracy of 10µs, and an output current accuracy of 0.1A.

[0072] The third PWM drive signal is connected to the MOS field-effect transistor Q9 on the high-frequency switching circuit, and the frequency and duty cycle of the final output pulse current are modulated by Q9.

[0073] The DSP controller is also connected to a human-computer interaction system, which includes a keypad and an LCD screen.

[0074] The keypad is used to set the first current value and welding time of the first DC power supply output at each stage, the second current value of the second DC power supply output, and to set the frequency and duty cycle of the high-frequency pulse current.

[0075] The LCD screen is used to display real-time input parameter settings, real-time welding current, and fault type.

[0076] The sampling point of the current sampling circuit is the output terminal of the filter inductor after secondary rectification.

[0077] The first current sampling circuit collects the current value at the output terminal of the filter inductor L1.

[0078] The first current feedback signal acquired by the first current acquisition circuit is input to the DSP controller via ADC1.

[0079] The DSP controller calculates the first deviation value between the first current feedback signal and the preset first current corresponding value.

[0080] The DSP controller performs PID calculations based on the first deviation value to obtain the duty cycle of the first PWM signal output.

[0081] The first PWM signal is connected to the input terminal of the first PWM drive circuit, so that the output current of the first DC power supply forms a closed-loop control, and controls the output current of the first DC power supply to be equal to the preset first current value.

[0082] The second current sampling circuit collects the current value at the output terminal of the filter inductor L2.

[0083] The second current feedback signal acquired by the second current acquisition circuit is input to the DSP controller via ADC2.

[0084] The DSP controller calculates a second deviation value between the second current feedback signal and the preset corresponding value of the second current.

[0085] The DSP controller performs PI calculations based on the second deviation value to obtain the duty cycle of the second PWM signal output.

[0086] The second PWM signal is connected to the input terminal of the second PWM drive circuit, so that the output current of the second DC power supply forms a closed-loop control, and controls the output current of the second DC power supply to be equal to the preset second current value.

[0087] Furthermore, Figure 3 This is a schematic diagram of the process when outputting the base current in one embodiment.

[0088] When the field effect transistor Q9 is turned on in the high-frequency switching circuit, the current output from the second DC power supply flows directly from the positive terminal to the negative terminal through Q9, without passing through the arc load.

[0089] At this time, only the first DC power supply output is provided to the arc load.

[0090] Furthermore, Figure 4 This is a schematic diagram of the process when the peak current is output in one embodiment.

[0091] When the field effect transistor Q9 is turned off in the high-frequency switching circuit, the current output by the second DC power supply is superimposed on the current output by the first DC power supply.

[0092] The current from the combined superposition of the first and second DC power supplies is provided to the arc load.

[0093] Furthermore, the frequency and duty cycle of the high-frequency pulsed micro-TIG arc current can be modulated by controlling the on and off frequency and duty cycle of the field-effect transistor Q9.

[0094] like Figure 5 As shown, Figure 5 This is a current waveform diagram of a high-frequency pulsed composite DC precision micro TIG arc spot welding power supply in one embodiment.

[0095] To ensure the safe and reliable operation of the high-frequency pulse composite DC precision micro-TIG arc spot welding power supply, a fault detection circuit is provided.

[0096] The fault detection circuit includes overvoltage and undervoltage protection at the power input terminal, and overcurrent and overtemperature protection on the inverter bridge module.

[0097] When the high-frequency pulse composite DC precision micro TIG arc spot welding power supply malfunctions, the DSP processor outputs a control signal to shut down the four MOS field-effect transistors on the first DC power inverter bridge and the four field-effect transistors on the second DC power inverter bridge, and displays the corresponding fault code on the LCD screen.

[0098] The DSP controller can also communicate with the host computer via an RS485 module, transmitting set parameters, welding data, etc. to the host computer.

[0099] The high-frequency pulse composite DC precision micro TIG arc spot welding method of the present invention will be described in detail below with reference to the accompanying drawings.

[0100] The high-frequency pulse composite DC precision micro-TIG arc spot welding method of the present invention can stably perform precision micro-TIG arc spot welding with an average current as low as 2A. This spot welding method can be realized based on the above-mentioned high-frequency pulse composite DC precision micro-TIG arc spot welding power supply. The arc current of this method is a high-frequency pulse waveform, which mainly includes the base value arc maintenance stage, the base value gradual rise stage, the main welding stage, the base value gradual fall stage, and the base value arc termination stage.

[0101] The base value arc-maintaining stage: after the arc is detected to be successfully ignited, a high-frequency pulse current is superimposed, and the base value current output by the first DC power supply is adjusted to reduce the arc current to maintain a stable arc combustion state.

[0102] The base current gradual increase stage: After the arc is stably burning and the preheating time is set, the base current output by the first DC power supply is gradually increased to the base current value set for the main welding stage within a set time.

[0103] The main welding stage: During the welding process, the base current output by the first DC power supply is maintained at the set welding current value;

[0104] The base value descent phase: When the welding process ends, the base value current output by the first DC power supply is gradually reduced to the set arc-ending current value within a set time.

[0105] The base value arc-ending stage: within a set time, the base value current output by the first DC power supply is maintained at the set arc-ending current value, and then finally reduced to zero.

[0106] In this embodiment, the high-frequency pulse composite DC precision micro-TIG arc spot welding method immediately outputs a high-frequency pulse current after successful arc ignition is detected. The base current output by the first DC power supply is quickly brought into the arc-maintaining state through PID regulation. After the micro-TIG arc is stably burning and preheating for a certain period of time, the base current slowly rises to the main welding current value and enters the main welding stage. After the end of this stage, the base current slowly drops to the base arc-ending current value until the base arc-ending stage ends and the current output stops.

[0107] The output of high-frequency pulsed current begins when the high-frequency arc ignition is successfully detected and continues until the arc termination stage ends, spanning the entire welding process.

[0108] like Figure 6 As shown, Figure 6 The given embodiment is illustrated in the current process diagram. Specifically, the high-frequency pulse composite DC precision micro-TIG arc spot welding method is as follows:

[0109] The pre-ventilation stage t1: When starting welding, first open the solenoid valve to send the protective gas through the welding torch to the welding area and remove the unfavorable gas in the welding area.

[0110] The base value arc-maintaining stage t2: After the early ventilation stage ends, the first DC power supply and the arc-starting circuit are immediately turned on. When the arc-starting is successfully detected, a high-frequency pulse current Ip is immediately superimposed, and the base value current output by the first DC power supply is quickly brought into the arc-maintaining state current value I1 through PI regulation.

[0111] The base current gradual increase stage t3: After the base arc maintenance stage t2 ends at t4, the base current output by the first DC power supply is gradually increased to the base current value I2 set for the main welding stage within the set time t3.

[0112] The main welding stage t4: During the main welding process, the base current output by the first DC power supply is maintained at the set welding current value I2 for a duration of t4.

[0113] The base value descent stage t5: When the main welding process ends, the base value current output by the first DC power supply is gradually reduced to the set arc-ending current value I3 within a set time t5.

[0114] The base value arc-ending stage t6: During the set time t6, the base value current output by the first DC power supply is maintained at the set arc-ending current value I3, and then reduced to zero.

[0115] The delayed gas cut-off stage t7: After the high-frequency pulsed arc is extinguished, the gas supply continues for a period of time t7, so that the welded joint is cooled in the protective gas to avoid oxidation.

[0116] The time interval t7-t7 is set in milliseconds (ms), and the values ​​of the first DC power supply and the high-frequency pulse current are set with a resolution of 0.1 amperes (A) to achieve precise control of time and current.

[0117] like Figure 7 The arc pattern of the high-frequency pulse composite DC precision micro TIG arc spot welding process of Φ0.5mm stainless steel wire in one embodiment is as follows: the power supply output current waveform is a base current of 2A, a high-frequency pulse amplitude of 5A, a frequency of 20kHz, a duty cycle of 20%, and an average current of 3A.

[0118] like Figure 8 The arc pattern of a high-frequency pulse composite DC precision micro TIG arc spot welding process of a 1.0mm thick stainless steel sheet in one embodiment is as follows: the power supply output current waveform is a base current of 1A, a high-frequency pulse amplitude of 10A, a frequency of 20kHz, a duty cycle of 10%, and an average current of 2A.

[0119] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," or "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0120] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0121] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply, characterized in that, It includes a main circuit consisting of a first DC power supply, a second DC power supply and a high-frequency switching circuit, and a control system for controlling the main circuit. The control system includes a DSP controller, a PWM drive circuit, a current sampling circuit, a fault detection circuit and a data communication circuit. Both the first DC power supply and the second DC power supply include a three-phase rectifier, a capacitor filter, an inverter bridge, a high-frequency transformer, a secondary rectifier, and an output filter circuit connected in sequence. The high-frequency switching circuit is connected to the output terminal of the second DC power supply. After being modulated by the MOS field-effect transistor of the switching circuit, a high-frequency pulse current is obtained. The high-frequency pulse current is superimposed and combined with the DC current output by the first DC power supply and then provided to the arc load. The DSP controller is used to control the entire welding power supply, and the PWM drive circuit, current sampling circuit and fault detection circuit are connected to the DSP controller.

2. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 1, characterized in that, The high-frequency switching circuit consists of a MOS field-effect transistor and its RC snubber circuit. The drain (D) of the MOS field-effect transistor is connected to the positive terminal of the second DC power supply, and the source (S) of the MOS field-effect transistor is connected to the negative terminal of the second DC power supply. In the high-frequency switching circuit, when the MOS field-effect transistor is turned on, the current output from the second DC power supply flows directly from the positive terminal back to the negative terminal through the MOS field-effect transistor; when the MOS field-effect transistor is turned off, the current from the second DC power supply flows from the positive terminal back to the negative terminal through the arc load; therefore, by controlling the frequency and duty cycle of the MOS field-effect transistor's on and off states, the frequency and duty cycle of the pulse current output to the arc load can be modulated.

3. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 1, characterized in that, The current output from the second DC power supply, modulated by a high-frequency switching circuit, is superimposed and combined with the current output from the first DC power supply to supply the arc load. The base value of the high-frequency pulse current supplied to the arc load by the superimposed composite is equal to the current value output by the first DC power supply, and the pulse amplitude of the high-frequency pulse current is equal to the current value output by the switching circuit.

4. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 1, characterized in that, The DSP controller is connected to the input terminal of the PWM drive circuit, and controls the on and off of the corresponding MOS field-effect transistor through the output signal of the drive circuit. The PWM driving circuit includes a first driving circuit, a second driving circuit, and a third driving circuit; The first driving circuit is connected to the MOS field-effect transistor of the inverter bridge of the first DC power supply, the second driving circuit is connected to the MOS field-effect transistor of the inverter bridge of the second DC power supply, and the third driving circuit is connected to the MOS field-effect transistor of the high-frequency switching circuit. The output terminal of the driving circuit is connected to the gate (G) and source (S) of the MOS field-effect transistor.

5. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 4, characterized in that, The current sampling circuit includes a first current sampling circuit and a second current sampling circuit; the first current sampling circuit collects the filtered current output from the first DC power supply and obtains a first feedback current signal. The second current sampling circuit collects the filtered current output from the second DC power supply and obtains the second feedback current signal. Based on the first feedback current signal, the DSP controller outputs a first PWM signal to the first drive circuit; The first PWM signal is used to adjust the output current value of the first DC power supply; The step of outputting the first PWM signal according to the first feedback current signal includes: obtaining a first deviation between the first feedback current signal and a preset first current corresponding value, and then using PI control to adjust the duty cycle according to the first deviation to obtain the first PWM signal; Based on the second feedback current signal, the DSP controller outputs a second PWM signal to the second drive circuit; the second PWM signal is used to adjust the output current value of the second DC power supply. The step of outputting the second PWM signal based on the second feedback current signal includes: obtaining a second deviation between the second feedback current signal and a preset second current corresponding value, and then using PI control to adjust the duty cycle according to the second deviation to obtain the second PWM signal.

6. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 1, characterized in that, The high-frequency pulse composite DC precision micro TIG arc spot welding power supply also includes a human-machine interaction system connected to the DSP controller. The human-computer interaction system includes a keypad and an LCD screen. The keypad is used to set the first current output by the first DC power supply, the welding time, the second current output by the second DC power supply, and the frequency and duty cycle of the high-frequency pulse current at each stage. The LCD screen is used to display real-time input parameter settings, real-time welding current, and fault type.

7. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 1, characterized in that, The closed-loop feedback of the current sampling circuit is implemented using a digital PID algorithm.

8. The high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to claim 1, characterized in that, The fault detection circuit includes an over-temperature detection circuit and an over-current detection circuit.

9. A high-frequency pulsed composite DC precision micro-TIG arc spot welding method, applied to the high-frequency pulsed composite DC precision micro-TIG arc spot welding power supply according to any one of claims 1 to 8, characterized in that, This includes the high-frequency pulse current waveform, the base value arc-maintaining stage, the base value gradual rise stage, the main welding stage, the base value gradual fall stage, and the base value arc-ending stage. The base value arc-maintaining stage: after the arc is detected to be successfully ignited, a high-frequency pulse current is superimposed, and the base value current output by the first DC power supply is adjusted to reduce the arc current to maintain a stable arc combustion state. The base value gradual increase stage: After the electric arc is stably burning and the preheating time is set, the base value current output by the first DC power supply is gradually increased to the base value current value set in the main welding stage within a set time. The main welding stage: During the welding process, the base current output by the first DC power supply is maintained at the set welding current value; The base value descent phase: When the welding process ends, the base value current output by the first DC power supply is gradually reduced to the set arc-ending current value within a set time. The base value arc-ending stage: for a set time period, the base value current output by the first DC power supply is maintained at the set arc-ending current value, and then reduced to zero. The high-frequency pulse current waveform: After successful arc ignition, the high-frequency pulse current is superimposed on the base current output by the first DC power supply until the base current drops to zero.

10. A high-frequency pulsed composite DC precision micro-TIG arc spot welding method according to claim 9, characterized in that, The process includes an early gas supply phase before the baseline arc-maintaining phase and a delayed gas shut-off phase after the baseline arc-closing phase.

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