CN105108276A - Commutation control method and commutation control system for variable polarity welding power source - Google Patents
Commutation control method and commutation control system for variable polarity welding power source Download PDFInfo
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- CN105108276A CN105108276A CN201510583402.3A CN201510583402A CN105108276A CN 105108276 A CN105108276 A CN 105108276A CN 201510583402 A CN201510583402 A CN 201510583402A CN 105108276 A CN105108276 A CN 105108276A
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- current
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- variable polarity
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
- B23K9/1006—Power supply
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
Abstract
The invention discloses a commutation control method and commutation control system for a variable polarity welding power source. Commutation comprises EN-EP commutation and EP-EN commutation, wherein EN signifies electrode negative, and EP signifies electrode positive. (1) When the EN-EP commutation is conducted, the commutation speed is controlled to be as quick as possible to prevent an arc blowout; and (2) when the EP-EN commutation is conducted, the commutation speed is lowered to lower a current impulse. The commutation control method and commutation control system for the variable polarity welding power source are easy to conduct; not only can the current impulse in the commutation process be restrained significantly, but also the arc blowout phenomenon in the commutation process can further be avoided.
Description
Technical field
The invention belongs to the source of welding current and control application, relate to a kind of reverse control method and reversing control system of variable polarity welding power supply.
Background technology
Variable Polarity electric arc argon tungsten-arc welding be that Al and Alalloy welds conventional electric arc type in plasma welding method, under the prerequisite of negative electrode atomizing ensureing Al and Alalloy welding requirements, tungsten electrode scaling loss can be reduced as far as possible, obtain good working effect.At present, research for the dynamic characteristic of electric arc is all using alternating current arc as research object usually, measure the current-voltage waveform curve (as shown in Figure 1a) when changing in time, or measure current-voltage relation curve (as shown in Figure 1 b).Thermal inertia effect due to electric arc causes the ascending curve of current/voltage not overlap with decline curve, positive-negative half-cycle almost symmetry.Electric arc is a kind of non-linear resistive load to have people to think for this feature, and namely electric current is identical with voltage-phase, in non-linear relation.
In this case electric arc, in commutation process, due to the effect of its thermal inertia, needs certain commutating period, so in commutation process, the unstable phenomenon even extinguished often appears in electric arc, and is attended by serious tungsten electrode scaling loss.For ensureing arc stability burning, avoiding blow-out phenomenon as far as possible, usually taking following several measure: 1, improving floating voltage; 2, to connect in source of welding current loop certain inductance; 3, improve the waveform of arc current, improve commutating speed as much as possible.Under normal circumstances, series inductance not only can reduce the operating efficiency of the source of welding current, also can affect the dynamic response capability of power supply to load simultaneously, and then affect welding effect; And improve the danger that floating voltage can strengthen welding operation personnel.
Publication number is that the Chinese patent of CN101352776 discloses a kind of variable polarity welding power supply secondary inverter circuit and control method (application number is 200810222503.8) thereof, its core is, when before switching, electric current is too small, increase electric current before the handover, when before switching, electric current is excessive, electric current is reduced at switch, and it is identical with EN-EP commutation strategy in EP-EN commutation, see its Fig. 6, but this control method is not from essence and the theoretical model of commutation, and also do not provide test waveform in this patent, therefore, actual test effect leaves a question open.
Therefore, the reverse control method and the reversing control system that design a kind of novel variable polarity welding power supply is necessary.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of reverse control method and reversing control system of variable polarity welding power supply, reverse control method and the reversing control system of this variable polarity welding power supply are easy to implement, significantly can suppress the rush of current in commutation process, and avoid the blow-out phenomenon in commutation process.
The technical solution of invention is as follows:
A reverse control method for variable polarity welding power supply, described commutation comprises EN-EP commutation and EP-EN commutation; Wherein to represent that electrode connects negative for EN, and EP represents that electrode just connects; It is characterized in that:
(1) when EN-EP changes, conversion speed is controlled fast as far as possible, to prevent blow-out;
(2) when EP-EN changes, conversion speed is reduced to reduce rush of current.
Reduction conversion speed when EP-EN changes refers to and arc current is dropped to below preset lower limit value Imin in several control cycle before EP-EN conversion; Imin is 1 ~ 5% of average arc electric current.
Control conversion speed when EN-EP changes refers to as far as possible soon in the several control cycles before EN-EP conversion and ensures that arc current value is higher than preset upper limit value Imax; Usually this additional current of commutation is exactly of short duration pulse, and several control cycle is additional in advance, and the duration is exactly these control cycles usually; Preset upper limit value Imax is 100-150A.
If electrode meets negative electricity arc current IEN < Imax, then before commutation, increase one and connect the pulse of negative electricity arc, the amplitude of this current impulse is more than or equal to Imax; The width of pulse is several control cycle.If IEN >=Imax, then special control is not increased to the current of commutation.
Several control cycle refers to 1 ~ 5 control cycle.
Control cycle is 50us.
A reversing control system for variable polarity welding power supply, comprises main circuit module, control circuit module and drive circuit module;
Main circuit part adopts the structure of twin inverter, and namely inverter adopts the size of pwm pattern regulation output electric current, and secondary inverting device is used for output current frequency and positive and negative half-wave current amplitude, time than the Variable Polarity electric current that can regulate respectively;
Control circuit module drives an inverter and secondary inverting device by drive circuit module; Above main circuit module, control circuit module and drive circuit module are existing mature technology;
Have microprocessor in control circuit module, microprocessor controls an inverter and secondary inverting device based on the reverse control method of aforesaid variable polarity welding power supply.
Drive circuit module adopts M57962L driver module, and microprocessor adopts DSP.
In alloyed aluminium variable polarity welding procedure, when selecting amplitude and the time value of Variable Polarity electric current, except considering the cleaning of aluminum alloy surface oxide-film and reducing except tungsten electrode scaling loss, Variable Polarity arc stability is the problem that must consider.Due to the effect of electric charge inertia battery, when not using commutation strategy, I
eN(electrode connects negative current) is 50A, I
eP(electrode connects positive current) is 100A, frequency be the variable polarity power source welding process of 50Hz as shown in Figure 4, wherein A is current curve, and B is voltage curve., in welding process, in time changing from DCEN to DCEP, can often there is current interruption phenomenon in us as can be seen from figure.And when changing from DCEP to DCEN, do not occur blow-out problem, but very large rush of current can be produced during commutation.Therefore certain measure should be taked to solve this two problems.
The object of the invention is based on Variable Polarity TIG[and argon tungsten-arc welding] weld the power supply in use special state that presents of welding arc, propose to be applicable to the commutation strategy that TIG welds Variable Polarity electric arc, can also ensure that while pilot arc is stable the arc load of the source of welding current to change has capability of fast response, thus obtain better welding effect.
Be 50A when welding parameter is IEN (electrode connects negative current); IEP (electrode connects positive current) is 100A; Frequency is 50Hz.Record dynamic characteristic as shown in Figure 3.Following problem is found: non-resistance, two anisotropies, by the impact of size of current to the characteristic research of Variable Polarity ARC commutating dynamic process.
Based on the specific question that above several welding arc finds in commutation process, introduce a kind of brand-new electric charge commutation dynamic process model, be referred to as electric charge inertia galvanic action model.
Technology path of the present invention illustrates: Variable Polarity electric arc exists from EN-EP and EP-EN (wherein EN represent that electrode connects negative and EP represents that electrode just connects) two transfer processes, electric arc easy blow-out when changing from EN-EP, improve conversion speed (improve arc current waveform, adopt Variable Polarity square wave to weld as far as possible) and effectively can prevent blow-out; When EP-EN changes, be not easy blow-out, too fast conversion speed easily forms excessive rush of current simultaneously.Therefore, conversion speed to be controlled when EN-EP changes fast as far as possible, and when EP-EN changes, suitably reduce conversion speed to reduce rush of current.
Beneficial effect:
The present invention is directed to the research that the different phenomenon that occurs of Variable Polarity difference commutation direction is done, find in certain current range, forward is born conversion and easily blow-out is occurred, negative sense is just being changed easy overcurrent and is being occurred impacting, so propose a whole set of the commutation control mode for this phenomenon, experiment proves the validity of the inventive method.
The reverse control method of variable polarity welding power supply of the present invention and reversing control system, when EN-EP changes, control conversion speed fast as far as possible, to prevent blow-out, when EP-EN changes, reduce conversion speed to reduce rush of current, therefore, (1), effectively can maintain the burning of Variable Polarity arc stability, not extinguish; (2), the equivalent damping of dynamic arc in power supply commutation process can be effectively avoided to change causing rush of current to the adverse effect of power supply and welding effect.
Accompanying drawing explanation
Fig. 1 is alternating current arc dynamic characteristic schematic diagram;
Fig. 2 (a) is variable polarity power source system block diagram;
Fig. 2 (b) is the schematic diagram that positive and negative electrode is carried on workpiece;
Fig. 2 (c) connects positive current and connects negative current schematic diagram;
Fig. 3 is variable polarity power source broken line analysis figure;
Fig. 4 is DCEN when be 50A, DCEP being 100A without the tactful welding current voltage oscillogram of commutation;
Fig. 5 is the current-voltage waveform figure after adopting EP-EN commutation strategy;
Fig. 6 is the welding current schematic diagram without commutation strategy;
Fig. 7 is the welding current schematic diagram adopting commutation strategy;
Fig. 8 is the current-voltage waveform figure after adopting EN-EP commutation strategy;
Fig. 9 is electric current is 200A welding current waveform figure.
Detailed description of the invention
Below with reference to the drawings and specific embodiments, the present invention is described in further details:
Embodiment 1:
For ensureing the commutating speed of variable polarity welding power supply, use the two inversion variable polarity power source of digitlization, as shown in Figure 2, whole digitlization inverter is made up of three parts structure, respectively: main circuit module, control circuit module and drive circuit module.In order to reach the requirement of power supply Variable Polarity, main circuit part adopts the structure of two inversion, namely an inversion adopts the size of pwm pattern regulation output electric current, and secondary inverting is used for output current frequency and positive and negative half-wave current amplitude, time than the Variable Polarity electric current that can regulate respectively.The employing of control circuit part take DSP as the control module of core, and major function is: the collection of signal and calculating, the control of welding process; the protection of power supply; the output (inversion) of pwm control signal, the control of Variable Polarity exports (secondary inverting), man-machine interaction.The realization of this control module all functions based on DSP is all come by the mode of software programming, and this is also a large feature of digitlization power supply.Drive circuit is the M57962L driver module selected according to the groundwork element IGBT of main circuit, can export satisfactory drive waveforms, and can play the effect of control circuit and main circuit insulation blocking for IGBT.
Small area analysis commutation control strategy is adopted: before being switched to EN from EP when EP changes EN into, first arc current is reduced and (describe first in advance several control cycle below electric current is dropped to 0[to be reduced to 0, in fact, before EP-EN conversion, in several control cycle, arc current is dropped to below preset lower limit value Imin; Imin is 1 ~ 5% of arc current mean value], then carry out polarity switching, adopt and reduce commutating speed in this way.Because according to electric charge inertia battery principle, now reduce the electron emissivity that commutating speed is of value to balance negative electrode, can dash current be reduced.The reduction of arc current is to ensure premised on arc stability, and find in test in the several control cycles (control cycle is 50us) before commutation, electric current to be down to zero, electric arc still can keep stable, and dash current reduces greatly.Three sections of different arc currents are defined: 1. normal EP electric current, 2. transitional EP electric current, 3. normal EN electric current (as shown in Figure 6) after have employed such control strategy.Fig. 5 is the current-voltage waveform adopting 100A after this control strategy, can observe welding current very stable, and rush of current when polarity switches comparatively Fig. 3 obviously reduce.
Control mode when EN changes EP into is: before being switched to EP from EN, stabilising arc is carried out by applying current impulse, namely workpiece by just become negative before the rear edge of current waveform, ensure the high value (if electric current is now less than the pulse of 100A with regard to an additional 100A, being greater than 100A just need not increase pulse) of electric current; The object improving electric current is, Variable Polarity electric arc improves arc temperature before becoming reversed polarity, so just can improve the degree of ionization of electric arc instantaneously, thus improve Variable Polarity electric arc is become contravariant polarity chron arc stability by positive polarity, because the response speed of system is very fast, therefore only need shift to an earlier date several control cycle and the raising of the set-point of electric current can be reached stabilising arc effect.The current waveform schematic diagram that Fig. 6 adopts when being normal weld, Fig. 7 is the welding current waveform schematic diagram adopting current impulse stabilising arc commutation strategy, Fig. 8 is the current-voltage waveform of 50A after this control strategy of employing, as can be seen from the figure, at the end of EN along there being a current spike, this spike is the current impulse of applying.Also find in test in addition, as long as this pulse value reaches 100A, (electric current is originally exactly the 50A represented in figure) just can reach good stabilising arc effect.According to the model of electric charge inertia battery theory, the effect of the electric current before conversion larger " electric charge inertia battery " is stronger, therefore when average welding current is more than 100A, when being changed to EP by EN, even if there is no additional commutation strategy (applying pulse that commutation strategy here refers to), the stability of Variable Polarity electric arc also can be ensured.Fig. 9 for not have the tactful I of additional commutation at EN in EP transfer process
eN(electrode connects negative current) is 200A, I
eP(electrode connects positive current) is welding current during 200A, and as can be seen from the figure, when welding current is 200A, even if do not have additional commutation strategy, Variable Polarity electric arc can ensure smooth combustion and smooth transition.
(power supply architecture aspect is prior art to variable polarity power source.) positive-negative polarity that the refers to power supply (being similar to a little traditional alternating current) that can become, butt welding fetches normally both ends of power, one end is connected on electrode, one end is connected on workpiece, so relative to electrode, present source current state is described, represent with EN and EP, namely electrode connects to bear and just connects with electrode.See the position designating electrode and workpiece in Fig. 2, Fig. 2 b.
Claims (8)
1. a reverse control method for variable polarity welding power supply, described commutation comprises EN-EP commutation and EP-EN commutation; Wherein to represent that electrode connects negative for EN, and EP represents that electrode just connects; It is characterized in that:
(1) when EN-EP changes, conversion speed is controlled fast as far as possible, to prevent blow-out;
(2) when EP-EN changes, conversion speed is reduced to reduce rush of current.
2. the reverse control method of variable polarity welding power supply according to claim 1, is characterized in that, the reduction conversion speed when EP-EN changes refers to and arc current is dropped to below preset lower limit value Imin in several control cycle before EP-EN conversion; Imin is 1 ~ 5% of average arc electric current.
3. the reverse control method of variable polarity welding power supply according to claim 1, it is characterized in that, the control conversion speed when EN-EP changes refers to as far as possible soon in the several control cycles before EN-EP conversion and ensures that arc current value is higher than preset upper limit value Imax; Preset upper limit value Imax is 100-150A.
4. the reverse control method of variable polarity welding power supply according to claim 3, it is characterized in that, if electrode meets negative electricity arc current IEN < Imax, then before commutation, increase one and connect the pulse of negative electricity arc, the amplitude of this current impulse is more than or equal to Imax; The width of pulse is several control cycle.
5. the reverse control method of the variable polarity welding power supply according to any one of claim 2-4, is characterized in that, several control cycle refers to 1 ~ 5 control cycle.
6. the reverse control method of variable polarity welding power supply according to claim 5, is characterized in that, control cycle is 50us.
7. a reversing control system for variable polarity welding power supply, is characterized in that, comprises main circuit module, control circuit module and drive circuit module;
Main circuit part adopts the structure of twin inverter, and namely inverter adopts the size of pwm pattern regulation output electric current, and secondary inverting device is used for output current frequency and positive and negative half-wave current amplitude, time than the Variable Polarity electric current that can regulate respectively;
Control circuit module drives an inverter and secondary inverting device by drive circuit module;
Have microprocessor in control circuit module, microprocessor controls an inverter and secondary inverting device based on the reverse control method of the variable polarity welding power supply described in claim 1-4,6 any one.
8. the reversing control system of variable polarity welding power supply according to claim 7, is characterized in that, drive circuit module adopts M57962L driver module, and microprocessor adopts DSP.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109551083A (en) * | 2017-09-26 | 2019-04-02 | 株式会社达谊恒 | Exchange non-consumable electrode arc welding control method |
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|---|---|---|---|---|
| JPS61206573A (en) * | 1985-03-11 | 1986-09-12 | Nippon Steel Corp | Method and device for current feed for dc arc welding |
| US5416299A (en) * | 1989-08-02 | 1995-05-16 | Mitsubishi Denki Kabushiki Kaisha | Pulse welding apparatus |
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| 丁坤等: "变极性TIG焊电弧负载特性及换向控制策略", 《焊接学报》 * |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109551083A (en) * | 2017-09-26 | 2019-04-02 | 株式会社达谊恒 | Exchange non-consumable electrode arc welding control method |
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