CN100354064C - Welding control method of diplonema MAG and welding source - Google Patents

Abstract

A double-wire MAG welding control method, which compares the welding current feedback and voltage feedback with the given signal in time division according to the predetermined requirements, and controls the main circuit to perform welding through the control circuit, so that the welding frequency remains unchanged during the welding process , a method for two welding machines to maintain a certain phase relationship so as to ensure welding stability; the control power supply designed according to this control method is characterized in that a switching circuit (B) is used in the control circuit part (9), mainly including input terminals respectively The current acquisition circuit (B1) and voltage acquisition circuit (B2) connected to the main circuit part, and the switching switch (B3), comparator (B4) and integral proportional regulator (B5) connected in sequence, the integral proportional regulator through The amplifying circuit (4.2) outputs the signal to the welding power output part (8.7). The invention realizes phase control of two motors, improves arc stability and reduces spatter.

Description

A twin-wire MAG welding control method and its welding power source

technical field

The invention relates to a control method for double-wire MAG welding and a welding power source thereof, belonging to the field of welding equipment and automation.

Background technique

Twin-wire MAG welding, as a feasible high-efficiency welding method, is still in the development stage. Everyone's understanding of this method is not completely the same, and there is no consensus on some specific issues. From the perspective of the form of the process, there are mainly two types, one is synchronous twin arc (Twin arc), and the other is independent twin arc (Tandem). The process characteristics of these two forms are different. For the form of the Twin arc system, two identical pulse welding power sources are used (only one power source can also be used), two sets of wire feeding mechanisms, and one conductive tip that can accommodate two welding wires (the two wires are not insulated from each other) , sharing a molten pool. When welding, the output pulse frequency of the two power sources is the same, and the current passed by the two welding wires is also the same, that is, the two wires melt into the molten pool at the same speed. The advantage of Twin arc is that the self-adjustment of the arc is used, and there is no need for coordinated communication control between the two power supplies, and the system is relatively simple, as shown in Figure 1. But its shortcomings are also obvious, such as the poor controllability of the arc, the strong mutual influence between the two welding wires, and it is difficult to accurately control the melting and droplet transfer of the two welding wires. The Tandem system, as shown in Figure 2, also uses two identical pulse welding power sources and two sets of wire feeding mechanisms. The difference is that two mutually insulated conductive tips are used, and the two power sources are coordinated and controlled through communication. , making the welding process of the two power sources more rapid and perfect. The pulse energy of these two power supplies is constant, ensuring that one pulse transfers one droplet at any current. The biggest difference from the Twin arc system is that the Tandem system allows the two power sources to set different welding parameters, which can be controlled through coordination, so that the degree of mutual interference between the arcs during twin wire welding with high current can be reduced. Therefore, the Tandem welding method is generally respected in the industry. However, regardless of the process form, the existing products are not particularly satisfactory in terms of arc stability, weld shape and phase controllability, and have large spatter. Tracing it to its cause, this is due to the improper control method of the inverter power used.

Most of the control methods of welding inverter power supply now adopt double closed-loop control method, the outer loop is the voltage loop, and the inner loop is the current loop, as described in the patent ZL99103518.6. The state quantity controlled by it is current I. For different welding methods with different welding state stages, although the current waveform requirements of each stage control are different, the feedback quantity is a single quantity current, so there is no signal switching problem. This control method commonly used in inverter welding machines is referred to as a double constant current or multiple constant current control method, as described in patent 03127961.9. In the pulse welding process, in order to ensure that the transition process is one pulse and one drop, the time of the pulse phase and the magnitude of the pulse current remain unchanged, but the pulse base value time is changed, so its frequency is always changing. However, for the twin-wire MAG welding using the Tandem process, since the welding machine and the wire feeder are composed of two sets, in order to reduce the mutual interference between the two welding equipment and improve the welding stability, it is necessary to establish a A coordinated working mechanism should be used to make it work stably in a predetermined state through coordinated control. Therefore, when the two welding machines work at a relatively fixed frequency, the dual constant current and multiple constant current control methods commonly used in single wire welding equipment show their incompatibility. Moreover, even if some other methods can be used to control the phase relationship between the two welding machines to be fixed, they are mostly limited to the two extreme cases of the same phase and the reverse phase, and cannot achieve arbitrary adjustment of the phase to adapt to different welding conditions, so its application is limited. Very restrictive.

Contents of the invention

Based on the deficiencies of the control method commonly used in single-wire welding and the existing double-wire MAG welding control method, the purpose of the present invention is to: use the Tandem process to propose a method that can well control the coordinated work of two welding machines and ensure arc stability. A phase-controllable twin-wire MAG inverter welding control method and a corresponding welding power supply for reducing the mutual interference of the two arcs and good weld seam formation.

The control method of the twin-wire welding system proposed by the present invention is characterized in that it compares the welding current feedback and voltage feedback with the corresponding given signal in time division according to the predetermined requirements, and controls the main circuit to perform welding through the control circuit. During the welding process, the welding frequency is guaranteed to be constant, and the two welding machines maintain a certain phase relationship to ensure welding stability; this method is realized in two twin-wire welding power sources with mutual communication. Its system includes main circuit part 8 and control circuit part 9, wherein control circuit part 9 includes core control part A, control execution part B, peripheral equipment control and execution part C, front panel input and keyboard/display part D. Wherein the input of the control circuit part 9 includes the welding current sampling B1, the voltage sampling B2 from the main circuit part 8 and the coordinated control signal C1 of another welder, and its output controls the inverter circuit 8.3 and the wire feeder of the main circuit; Specifically, it mainly includes the following steps in turn:

1) First, determine the welding parameters according to the actual requirements: including wire feeding speed V, peak voltage Up, peak time Tp, frequency F, base value current Ib, phase relationship DLY; its function is through the input on the front panel and the keyboard/display part D to fulfill;

2) When welding is performed, according to the input frequency F and peak time Tp, determine the timer value corresponding to the pulse phase and the base value phase, and start the software timer interrupt for automatic control conversion, so that in the pulse base value phase, the output The given signal and the feedback signal taken are the current given signal and the current feedback signal, that is, to ensure the constant current; in the pulse peak stage, the output given signal and the feedback signal taken are the voltage given signal and the voltage feedback signal, Make the welding machine output different control signals and given signals in different welding stages. Different closed-loop controls are thus formed to ensure stable welding under the condition that the frequency of each welding machine is constant, which is realized by the control circuit part 9 . The given A2 and the switching signal A3 are switched between the base value and the peak value at the same time according to the preset parameters to complete the voltage and current control;

3) During the welding process, while the master welder is converting from the base value to the peak value, it will send a serial communication signal to the slave welder through the serial communication circuit C1, and the slave welder will pass through its own serial communication circuit C1 in the After receiving this signal, set it as the base value stage, and determine the base value time according to the given phase relationship DLY value, and complete any specified phase difference control; this step is realized through serial communication interruption.

4) In process 3), if the slave welder fails to receive the interruption signal from the master welder due to interference and other factors, the slave welder will weld according to its original preset parameters until it receives the interrupt signal from the master welder. up to the serial communication signal.

The design idea of the present invention is: for the selection of the control method, that is, the core part of the present invention, a voltage-current control method is adopted. The so-called voltage-current control method is to ensure that the peak voltage (Up) and the base current (Ib) are constant during the welding process. The principle is: in the pulse peak stage, the feedback signal adopts the voltage to ensure that the voltage is a constant value. If the arc is disturbed, the recovery of the arc length mainly depends on the change of the peak current to cause the change of the average current to adjust. The adjustment ability of the system and the power supply related to the maximum output current. This method is actually a flat power supply characteristic during the peak period. When the arc length changes, the current deviation ΔI2 generated by this external characteristic will be greater than the current deviation ΔI1 of the external characteristic of the power supply, and the melting speed will change quickly, that is, the arc length of the flat external characteristic of the power supply will recover quickly. The self-regulation function of the power arc system is strong. This control method can achieve a stable transition process of one pulse and one drop through the adjustment of a wider peak current Ip range within a certain pulse width time Tp range. In the pulse base stage, the feedback signal adopts the current, that is, to ensure the constant current, so that the arc can ensure the current stability at this stage, and ensure that the arc burns stably and does not go out. This mode determines that the frequency of the entire pulse process is constant, so it can work stably under a predetermined phase difference and realize the preset welding process.

The welding power source designed according to the method of the present invention mainly includes a main circuit part 8 and a control circuit part 9 with a single-chip microcomputer as the control center. The line communication circuit C1 is connected with the power supply of another welding machine. The switching circuit B mainly includes a current acquisition circuit B1 and a voltage acquisition circuit B2 whose input terminals are respectively connected to the main circuit part, and a switching switch B3, a comparison link B4, an integral proportional regulator B5, and a pulse width modulation circuit connected in sequence. B6, IGBT drive circuit B8. Wherein the switch B3 includes two input ends, an output end and a control end: the two input ends are respectively connected with the current and voltage acquisition circuits B1 and B2, and the control end is connected with the switching signal A3 output by the single-chip microcomputer system, through the signal from the single-chip microcomputer The switching signal A3 is used to control the pair switching, so that it switches to the collection voltage during the welding pulse peak stage, and switches to the collection current during the welding pulse base value stage, and the output terminal is connected to the comparison link B4. The other input terminal of the comparison link B4 is connected to the given signal A2 output by the single-chip microcomputer system, and its function is to complete the comparison between the feedback current from B1 and the feedback voltage from B2 and the value from the given A2, and the difference input Go to Integral Proportional Regulator (PI) B5. The other input of the pulse width modulation circuit B6 is the protection circuit B7, and the output of the IGBT drive circuit B8 is the inverter circuit 8.3.

The control circuit part 9 mainly includes a core control part A, a control execution part B, a peripheral device control and execution part C, an input and a keyboard/display part D of the front panel; the core control part A is composed of a single-chip microcomputer system A1 , the input part includes the current sample B1 and the voltage sample B2 input to the A/D conversion A4 and the voltage sample B2 input to the short circuit judgment A5. Among them, the A/D conversion A4 is used to process the 80C196KC single-chip microcomputer system and the display part D during welding to display the actual welding current and voltage in real time; the short-circuit judgment signal A5 ensures that the single-chip microcomputer system can obtain information when a short-circuit occurs during welding Described peripheral equipment control and execution part C include the serial communication C1, the photoelectric isolation part C2, the output terminal that carries out two-way communication between the execution core control part A and another welder to the single-chip microcomputer system A1 through the photoelectric isolation part C2 Welding torch switch C3, the input terminal is connected to the single-chip system A1 through the photoelectric isolation part C2, the wire feed reference C4 and the gas valve C5, the input terminal is connected to the wire feed reference C4, and the output terminal is connected to the external wire feeder. Wire feeder speed control circuit C6; the input and display part D of the front panel includes a keyboard display drive circuit D1 whose input end is connected to the single-chip microcomputer system A1, a welding parameter display D3 whose input end is connected to the keyboard display drive circuit D1, and an output end through the keyboard display drive circuit The welding parameter preset D4 connected with the single-chip microcomputer system A1 of D1, and the given D2 of the coding knob connected with the single-chip microcomputer system at the output end.

Compared with the prior art, the control method adopted in the present invention and the welding machine power supply have the following advantages:

1. The welding process is stable, the spatter is small, and the arc stability is strong. Since the method of the present invention adopts the U/I control mode, the degree of interference between the two arcs can be better controlled, and a better matching of process parameters can be selected, so the stability of the arc can be improved and spatter can be reduced.

2. The welding specification is wide, and the phase can be matched arbitrarily. The welding machine established according to the control idea of the present invention uses two welding machines to communicate with each other, realizes the phase relationship matching of the two welding machines through software control, and can realize the phase adjustment control of the two welding machines from completely in phase to completely reverse phase .

3. By continuously switching between voltage and current through the sampling signal, the welding machine works at a relatively fixed frequency, which ensures the stability of welding. And because a switching circuit is added, the flexibility of welding machine control is increased. When only one sampling feedback signal of voltage or current is needed, it is also applicable by setting the switching signal A3 high or low, thereby greatly increasing the welding machine. Control flexibility.

Description of drawings

Figure 1 Schematic diagram of Twin arc welding system

Figure 2 Schematic diagram of Tandem welding system

For Figure 1 and Figure 2, where: 1-welding power supply, 2-welding nozzle, 3-wire feeder, 4-workpiece, 5-electric arc, 6-welding wire, 7-connection channel of two welding machines.

Figure 3 Structural composition diagram of welding machine

Figure 4 The specific circuit of the control execution part B

Figure 5 Main program software scheme diagram

Figure 6 Welding program block diagram

Figure 7 AD interrupt block diagram

Figure 8 Software timer interrupt block diagram

Figure 9 Block diagram of serial communication interruption of two welding machines

Detailed ways

This example will now be described with reference to the accompanying drawings.

This example uses the schema shown in Figure 2.

A concrete example of the present invention is shown in Fig. 3 as a structural diagram of a single welding machine, which generally includes two parts: the main circuit part 8 of the welding power supply and the control circuit part 9 with 80C196KC as the core. The input voltage of the main circuit is three-phase 380V; the input rectifier 8.1 is rectified by Fuji rectifier bridge, the model is FUJ6RI100G-160; The microcrystalline magnetic core has a transformation ratio of 15:2; the filter 8.6 uses a magnetic core saturated inductance, and the inductance is about 40μH; the control part adopts a control system based on 80C196KC single-chip microcomputer, which mainly completes the timing control and can realize the phase of the two welding machines The relationship varies from 0 to 180 degrees; the keyboard/display part adopts 8279 keyboard/display chip to realize the management of the keyboard and the dynamic scanning display of the digital tube. It will be described in detail below in conjunction with the accompanying drawings.

Its working sequence is: the three-phase input 380V AC is firstly rectified by the input rectification part in 8.1 and filtered in 8.2, and then becomes 540V DC. Afterwards, the direct current becomes 20KHZ alternating current after going through 8.3 inverter circuit (which is controlled by the control circuit part) and step-down isolation of 8.4 intermediate frequency transformer, and then becomes a large current for welding after passing through 8.5 output rectifier and 8.6 filter Low voltage DC, supply 8.7 welding power output. Since the working frequency of the above circuit is 20KHZ, and the output inductance is also very small (about 40μH), adjusting the inverter switching frequency or pulse width can achieve microsecond control, so this type of power supply has fast response and good dynamic performance.

The composition and functions of each part are as follows:

The core control part A is mainly composed of 80C196KC single-chip microcomputer, and its input part includes the current sampling B1 signal and voltage sampling B2 signal input to the A/D conversion A4 to obtain the welding real-time welding voltage and current value; the voltage sampling B2 signal input to the short circuit judgment A5 , to obtain a short-circuit signal to achieve the purpose of monitoring the welding state. The other input part is obtained from part C, including the coordinated control information input of another welding machine obtained from the serial communication circuit (C1) and the welding torch switch signal (C3) obtained after passing through the photoelectric isolation (C2). The third input part comes from the keyboard display of part D to input the drive circuit (D1) and the coding knob given (D2) part to obtain the initial welding parameters. Part A, as the core control part, mainly completes the response to welding parameter input and external signals, and controls the three parts B, C, and D after software processing and transformation, so that the entire welding system can coordinate and complete the predetermined welding purpose.

The hardware part of the present invention is mainly in the control execution part B, which is characterized in that: a switch B3 is added to control the conversion of the feedback signal. Its input part is the current sampling B1 and voltage sampling B2 derived from the welding power output part 8.7, and through the control of the switching signal A3 from part A, the current sampling B1 and the voltage sampling B2 are connected in time division, and then compared with the corresponding period of time After the given A2 is compared by the comparison link B4, it is input to the integral proportional adjustment (PI) B5, and is output to the pulse width modulation circuit B6 after signal processing. At the same time, the protection signal from the protection circuit B7 is also input to B6. After the signal is modulated by the PWM of B6, it is input to the IGBT drive circuit B8, and after processing, it is input to the inverter circuit 8.3 to complete this control function. The specific circuits of B3, B4, and B5 are shown in Figure 4: where U1A is the switch B3, this example uses H4053, its pins 1 and 2 are respectively connected to the voltage sampling B2 and current sampling B1, and pin 10 is connected to the switch through the resistor R1 Signal A3, pin 15 is the output pin, and its output signal is compared with the given signal A2 and then input to the negative phase input terminal (pin 2) of the amplifier U2 (CA3140), and the integral proportional adjustment is formed by the feedback resistor R6 and the capacitor C1 ( PI), and output to the pulse width modulation circuit B6 through the resistor R7. Among them, D1, R8, and R9 form a voltage limiting circuit to prevent the voltage output from R7 to the pulse width modulation circuit B6 from being too high.

Part C is the peripheral equipment control and execution part. Among them, the serial communication C1 executes the two-way communication between the core control part A of this welding machine and another welding machine, including the coordinated control and signal feedback of the two welding machines, so that it can work in a predetermined form and keep the two welding machines The machine works synchronously or with a certain phase angle difference according to the requirements. The photoelectric isolation part C2 executes the input from the torch switch C3 to part A, and the output control of part A to the wire feeding given C4 and gas valve C5. Among them, C4 achieves the purpose of controlling the external wire feeder through the speed regulating circuit C6 of the wire feeder, so that it can coordinate with the welding machine.

Part D is the input and keyboard/display part of the front panel. The welding parameter preset D4 displays the driving circuit D1 through the keyboard and coordinates with the coding knob to set D2, and inputs to the core control part A to realize the setting of welding parameters, and displays them through the welding parameter display D3. When welding, the core control part A displays the drive circuit D1 through the keyboard, and outputs to the welding parameter display D3, which displays the welding current and voltage, so that it can observe the welding parameters in real time.

Since the whole welding process of the present invention is carried out under the program control of the single-chip microcomputer system, this example will be further described in detail below in conjunction with the control method of the present invention and with reference to the program flow chart.

Figure 5 is a schematic diagram of the main program software of the single-chip microcomputer-controlled twin-wire MAG GMAW inverter welding power supply. The main software program includes: initialization subroutine, parameter preset, display and calculation subroutine, arc striking subroutine, delay subroutine and welding subroutine. The specific execution sequence of the main program is: after power-on reset, the program starts to run from the initial address (80C196KC is 2080H), and the system first executes the initialization subroutine to complete the initial value setting of each parameter. Then turn off the interrupt request, execute the keyboard scanning program, detect whether a control key is pressed, and process accordingly. Combined with the setting of the coding knob in the high-speed input inspection subroutine executed subsequently, the welding parameters such as wire feeding speed V, peak voltage Up, peak time Tp, frequency F, base value current Ib, and phase relationship DLY are obtained for welding process control, and then Display the relevant parameter settings through the display subroutine. The calculation program determines the base value time Tb=1/F-Tp according to the system clock adopted by the single-chip microcomputer, and determines the counter cycle numbers Nb and Np corresponding to the base value time and peak time according to the time of each counting cycle, for control conversion . For other given parameters, it is converted into the corresponding machine program value according to the specific welding machine parameters. For the high-speed input subroutine, if it is judged that there is a welding switch signal, check whether the welding torch switch register has an open command, and then transfer to the arc ignition and welding program until the welding end signal is detected, and exit the welding state. If there is no welding start signal, the previous program will be executed again after a certain time delay (such as 20ms).

The specific execution sequence of the main program is: after power-on reset, the program starts to run from the initial address (80C196KC is 2080H), and first initializes the system, including the definition of various parameter variables and registers. In the parameter preset and calculation part, the program will first scan and display each parameter, and store the welding parameters input by the user into the corresponding registers and variables. Then the program will calculate according to this parameter input, and convert it into the corresponding value related to the hardware for subsequent welding control. For the counter value required for the control of the switching signal A3 and given A2 in the software interrupt control, the base value time is first calculated from the frequency F and the time Up: $\mathrm{Tb}=\frac{1}{f}-\mathrm{Tp},$ Then, according to the time of each counter cycle, the counter values Np and Nb corresponding to Tp and Tb are determined. When there is a welding signal, the program will start the arc program. If there is a welding stop signal, it will jump out of the program, otherwise it will enter the welding program control.

As shown in Figure 6, it is a welding program block diagram, which mainly deals with the processing and judgment required in real time during the welding process. The process is as follows: firstly perform some "preprocessing" on the welding status, then "set the current", then judge "whether the arc is ignited", if the arc is not ignited, then execute the judgment "stop welding no", if it is Stop welding, then exit, otherwise it will jump back to the cycle of resetting the current and judging whether to lead the arc or not. If it is judged to be leading arc, execute "open serial communication" to carry out two-machine communication control. Then "set A/D and software timer interrupt". Next, "set the base value current", "set the welding parameter flag", start "set the software timer interrupt time". Then it will make a circular judgment on "whether there is a welding stop signal" at a certain time interval, and stop welding and jump out of the program when the stop signal occurs, otherwise it will wait for the judgment and respond to the interruption in a cycle.

The control method of the present invention is mainly embodied in the welding program process, and will be controlled by corresponding interruption in this process:

AD interrupt realizes the real-time detection and display of the welding current and welding voltage during the welding process;

The software timing interrupt completes the control of welding switching signal A3 and given A2;

The serial communication is interrupted to complete the phase relationship control of the two welding machines;

Accompanying drawing 7 is a block diagram of AD interruption. The main function is to realize the display function of welding voltage and current during welding. Its execution process is as follows: first perform preprocessing operations, complete some necessary settings, then judge whether it is current or voltage, and perform current or voltage sampling and display according to the results, and then reset the next sampling time and sampling variables (by timer and the setting of the corresponding register control bits to do this).

Figure 8 is a block diagram of the software timer interrupt. This subroutine is mainly to realize the size and conversion control of the base value and peak value of the welding pulse, determine the given signal A2 and switching signal A3 in Figure 3, and implement real-time control voltage/current conversion. The program first carries out "preprocessing", including the setting of protection site and timer value, base value and peak value flag. Then judge "Is there a welding torch input?" If there is no welding torch input, execute the judgment "No at the time", and if there is a welding torch input, execute "Set the flag", and then execute the judgment "No at the time", if it is time, jump out of the program, otherwise It executes the judgment of "is it the base value current?" If yes, "process the given and switching signal as current", otherwise "process the given and switching signal as voltage", then "restore the scene", and jump out of this program.

Figure 9 is a block diagram of the serial communication interruption program of two welding machines. Its function is to control the phase relationship of the two welding machines according to actual requirements, so as to ensure the coordinated work of the two welding machines. During welding, the main welder sends a coordination signal interrupt request at a specific moment in each welding cycle, and the slave welder responds to the interrupt after receiving this serial interrupt request, and controls the working status of the slave welder according to the preset phase requirements . The advantage of using external interrupt is that not only the software control is simple, but also when the coordination signal sent by the master welder cannot be received by the slave welder due to interference in the transmission process or other reasons, the slave welder can schedule according to its own schedule. The corresponding welding control is carried out by the specific welding program, which avoids the phenomenon of missing welding cycles caused by receiving errors from the welding machine. The specific interrupt process of the serial interrupt is as follows: when the interrupt response occurs, set the welding process to the base value stage, then set the time of the base value stage and wait until the time is up, and then execute the welding operation until the return jumps out.

For thin steel plate welding, this twin-wire welding equipment can realize high-speed and stable welding of 3m/min (plate thickness δ=2mm) and 2m/min (plate thickness δ=3mm) when using Ф1.2mm welding wire. For thick plates, it can It achieves a deposition rate of 10Kg/h, low spatter, good forming, and stable arc. Compared with the highest welding speed of single wire, it is only 1.5m/min, which greatly improves the efficiency. Meet the requirements of design and use.

The above is an example of the device and its control method, and we can also make some changes to it. For example, the main circuit part can use the half-bridge inverter circuit instead of the full-bridge form, the control part can use DSP or other single-chip microcomputer instead of 80C196KC to realize its functions, and the display part can use SD7218 instead of 8279, etc. As long as its control idea is consistent with what is described in the present invention, it should be regarded as included in the scope of the present invention.

Claims (3)

1, a kind of mariages MAG welding control method, it is characterized in that: it is a kind of welding current feedback and voltage feedback to be required timesharing and the comparison of given signal according to predetermined, and control main circuit by control circuit and weld, guarantee that in welding process welding frequency is constant, thereby two welding machines keep certain phase relation to guarantee the method for welding stability; This kind method is to realize respectively in two double wire welding power supplys with intercommunication mutually; Its system comprises main circuit part (8) and control circuit part (9); Wherein control circuit part (9) comprises core control section (A) again, control operating part (B), peripheral unit control and operating part (C), the input of front panel and display part (D); Wherein the input of control circuit part (9) comprises the coordination control signal (C1) of the welding current sampling (B1), voltage sample (B2) and another welding machine that derive from main circuit part (8), the inverter circuit (8.3) and the wire-feed motor of its output control main circuit; Specifically, it mainly may further comprise the steps successively:

1) at first according to actual requirement, determines welding parameter: comprise wire feed rate V, crest voltage Up, time to peak Tp, frequency F, background current Ib, phase relation DLY; Its function realizes by input and display part (D) of front panel;

2) when welding is carried out, frequency F and the time to peak Tp timer numerical value of determining stage pulse and base value stage correspondence according to input, and the startup software timer interrupts controlling automatically conversion, make it in the pulse base value stage, the given signal of output and the feedback signal of taking are given signal of electric current and current feedback signal, promptly guarantee the constant of electric current; In the peak value of pulse stage, the given signal of output and the feedback signal of taking are voltage given signal and voltage feedback signal, make welding machine at different different control signal and the given signals of welding stage output, constitute different closed-loop controls thus, thereby guarantee to realize stable welding under the constant condition of every welding machine frequency, this realizes by control circuit part (9); Given (A2) and switching signal (A3) are according to parameter preset, and voltage and current control is finished in conversion simultaneously between base value and peak value;

3) in welding process, main welding machine is when being converted to peak value by base value, will be by serial communication circuit (C1) to send a serial communication signals from welding machine, from welding machine by serial communication circuit (C1) itself after receiving this signal, be set and be the base value stage, and, determine this base value time according to given phase relation DLY value, finish any designated phase difference control; This step interrupts realizing by serial communication;

4) in process 3) in, if receive the interrupt signal that main welding machine sends, then will weld according to own original default parameter, till the serial communication signals of receiving main welding machine from welding machine because factors such as interference fail to make from welding machine.

2, the source of welding current of method design according to claim 1, mainly comprise main circuit part (8) and be the control circuit part (9) of control centre that it is characterized in that: described control circuit part (9) adopts commutation circuit (B) and SCM system to link to each other with the power supply of another welding machine by serial communication circuit (C1) with the single-chip microcomputer; Described commutation circuit (B) mainly comprises current acquisition circuit (B1) and the voltage collection circuit (B2) that input partly links to each other with main circuit respectively, and the change-over switch (B3), comparing element (B4), integration proportional controller (B5), pulse-width modulation circuit (B6), the IGBT drive circuit (B8) that connect in turn; Wherein change-over switch (B3) comprises two inputs, output and a control end: two inputs link to each other with electric current, voltage collection circuit (B1), (B2) respectively, control end links to each other with the switching signal (A3) of SCM system output, switch by controlling from the switching signal (A3) of single-chip microcomputer regularly, make it switch to collection voltage at the weld pulse peak phase, switch to the collection electric current in the weld pulse base value stage, output disconnecting comparing element (B4); Another input of comparing element (B4) links to each other with the given signal (A2) of SCM system output, its function is for being used for finishing from the feedback current of (B1) with from the feedback voltage of (B2) and comparison from the value of given (A2), and its difference is input to the integration ratio and regulates (B5); Another of pulse-width modulation circuit (B6) is input as holding circuit (B7), and IGBT drive circuit (B8) is output as inverter circuit (8.3).

3, control power supply according to claim 2, it is characterized in that: control circuit part (9) mainly comprises core control section (A), control operating part (B), peripheral unit control and operating part (C), the input of front panel and keyboard/display part (D); Described core control section (A) is made up of SCM system (A1), and the importation comprises current sample (B1) and the voltage sample (B2) that is input to A/D conversion (A4) and is input to the voltage sample (B2) of judging (A5) in short circuit; Wherein A/D conversion (A4) is used for passing through the processing of 80C196KC SCM system and display part (D) when welding, shows actual welding electric current and magnitude of voltage in real time; Short circuit is judged when signal (A5) guarantees that short-circuit conditions takes place in welding process, SCM system energy acquired information; Described peripheral unit control and operating part (C) comprise that carrying out core control section (A) is input to the arc welding gun switch (C3) of SCM system (A1), wire feed given (C4) and the air valve (C5) that input links to each other with SCM system (A1) by photoelectricity isolated part (C2), the wire-feed motor alignment circuit (C6) that input given with wire feed (C4), output link to each other with outside wire-feed motor with serial communication (C1), photoelectricity isolated part (C2), the output that another welding machine carries out two-way communication by photoelectricity isolated part (C2); The input of described front panel and display part (D) comprise that welding parameter that keyboard display driver circuit (D1) that input links to each other with SCM system (A1), the welding parameter that input links to each other with keyboard display driver circuit (D1) show that (D3), output link to each other with SCM system (A1) by keyboard display driver circuit (D1) presets the coding knob given (D2) that (D4), output link to each other with SCM system.

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