GB2039167A - Power source for arc welding - Google Patents
Power source for arc welding Download PDFInfo
- Publication number
- GB2039167A GB2039167A GB7943189A GB7943189A GB2039167A GB 2039167 A GB2039167 A GB 2039167A GB 7943189 A GB7943189 A GB 7943189A GB 7943189 A GB7943189 A GB 7943189A GB 2039167 A GB2039167 A GB 2039167A
- Authority
- GB
- United Kingdom
- Prior art keywords
- power source
- transformer
- welding
- rectifiers
- phase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000003466 welding Methods 0.000 title claims abstract description 45
- 238000004804 winding Methods 0.000 claims abstract description 14
- 238000009499 grossing Methods 0.000 claims abstract description 10
- 239000011261 inert gas Substances 0.000 claims description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 2
- 229910052721 tungsten Inorganic materials 0.000 claims description 2
- 239000010937 tungsten Substances 0.000 claims description 2
- 230000008901 benefit Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/22—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M5/25—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
- H02M5/27—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means for conversion of frequency
- H02M5/271—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means for conversion of frequency from a three phase input voltage
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F30/00—Fixed transformers not covered by group H01F19/00
- H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
- H01F30/12—Two-phase, three-phase or polyphase transformers
- H01F30/14—Two-phase, three-phase or polyphase transformers for changing the number of phases
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Arc Welding Control (AREA)
- Generation Of Surge Voltage And Current (AREA)
Abstract
In a power source for arc welding comprising a transformer (10), controllable rectifiers are provided for generating an alternating single- phase welding current with a welding current frequency which is one- and-one-half or three times the supply frequency. In order to provide a transformer which structurally is relatively small in size, and for the purpose of reducing the number of controllable rectifiers, the power source is characterized in that, the secondary winding (11) of the transformer (10) is connected to the workpiece (12) and to the welding torch (13), the primary winding (14) of the transformer (10) is provided with three delta-connected part-coils (15, 16, 17) which have identical windings, one end (15a, 16a, 17a) of each primary part-coil (15, 16, 17) is connected to a centre tap (M) of three smoothing chokes (18, 19, 20), the other end (15b, 16b, 17b) of each primary part-coil (15, 16, 17) is connected to one phase (R, S, T) of a three-phase network and to one terminal (21, 22, 23) of two anti- parallel-connected rectifiers (24/25, 26/27, 28/29), and the other terminals (30/31, 32/33, 34/35) of the rectifiers (24 to 29) are connected to the start (18a, 19a, 20a) and to the end (18b, 19b, 20b) of the smoothing choke (18, 19, 20). <IMAGE>
Description
SPECIFICATION
Power source for arc welding
The present invention relates to a power source for arc welding, comprising a transformer and controllable rectifiers, associated therewith, for generating an alternating singlephase welding current with a welding current frequency which is one-and-one half or three times the supply frequency.
The above statement refers to a state of the art which has become known, for example, from early published German Specification
No. 26 56 980. In this specification a power source for arc welding is described with which a single-phase alternating current can be generated, the frequency of which is selectively three or one-and-one-half times the values of the supply frequency (50 or 60 Hz), the threephase network being loaded symmetrically.
This is made possible by simple control of the rectifiers provided so that, at predetermined times, certain rectifiers are open or closed in such a manner that the above-mentioned frequency of the single-phase alternating welding current is produced.
With the higher frequency better welding characteristics with respect to ignition, stability of the arc and quality of the welding are achieved by more intensive agitation of the molten pool, leading to better welding results particularly in the alternating-current welding of aluminium.
A further advantage consists in that the single-phase loading by the welding arc is distributed symmetrically over the three-phase network, in the same manner as with a threephase-connected welding rectifier of the hitherto customary type of construction.
In addition, with this power source the structural size of the individual inductances (iron core chokes, air core chokes, transductors) required for tilting the current/voltage characteristics, as required by the welding process, or for setting the current, is reduced to a third while retaining the same action.
For the known power source, twelve controllable rectifiers are required for generating the required welding current frequency, which is not of advantage with respect to volumetric shape and production costs. In addition, the rectifiers are connected on the secondary side to a three-phase transformer, with the result that the transformer is of a considerable size.
It is an object of the present invention to improve a power source of the type mentioned above in such a manner that the above-mentioned disadvantages are avoided, particularly with reference to the structural size of the welding transformer and the number of controllable rectifiers.
In order to achieve this object, it is proposed according to the present invention to provide a power source which is characterised in that,
the secondary winding of the transformer is connected to the workpiece and to the welding torch,
the primary winding of the transformer is provided with three part-coils which are identical in their windings,
the one end of each primary part-coil is connected to a centre tap of three smoothing chokes,
the other end of each primary part-coil is connected to one phase of a three-phase network and to one terminal of two anti-parallelconnected rectifiers, and
the other terminals of the rectifiers are connected to the start and to the end of the smoothing choke.
This circuit arrangement has the advantage that, whilst retaining the advantageous welding current frequency and symmetrical threephase network loading described above, the structural size of the welding transformer is one third of the structural size of a supplyfrequency three-phase transformer and thus the whole secondary wiring can be provided in single phase and, therefore, in a time and material-saving manner. In addition, in the proposed circuit, only six controllable rectifiers are needed for generating an alternating single-phase welding current with a welding current frequency of one-and-one-half or three times the supply frequency, which, in conjunction with the advantageous transformer design, reduces the structural size and the weight of the welding system. On the other hand, the drive requirements are reduced which is of advantage for production and also for maintenance.
The controllable rectifiers are simultaneously used for adjusting the welding current by means of phase control so that expensive components for this purpose, such as leakagereactance cores, transductors, change-over windings with step switching, and so forth, can be omitted.
In addition, the invention provides the advantage that if the controllable rectifiers are wrongly driven (as a result of internal or external disturbances), there can be no short circuit between phases, with subsequent switch-off or failure of the whole power source, since there is always a transformer winding in the circuit concerned.
In the description which follows, the power source according to the invention is described in greater detail with reference to the accompanying drawings in which,
Figure 1 shows a block diagram of a power source for arc welding according to the invention, and
Figures 2 to 5 show current/voltage diagrams.
The power source shown in Fig. 1 is provided as a transformer 10 the secondary winding 11 of which is connected to a work piece 12 and to a welding torch 13.
The primary winding 14 of the transformer 10 is provided with three delta-connected part-coils 15, 16, 17 having identical windings. One end (15a, 16a, 17a) of each primary coil 15. 15. 17 is connected to a centre tap M of three smoothing chokes 18, 19, 20.
The other end (15b, 16b, 17b) of each primary part-coil 15, 16. 17 is connected to one phase R, S, T of a three-phase supply network and to one terminal 21, 22, 23 of two antiparallel-connected controllable rectifiers 24/25 and 36/27 and 28/29.
The other terminals 30/31 and 32/33 and 34/35 of the rectifiers 24 to 29 are connected to the start 18a, 19a, 20a and the end 1 8b, 19b, 20b of the smoothing chokes 18, 19, 20. It is of particular advantage if the controllable rectifiers 24-29 are constructed as thyristors. The thyristors 24-29 are driven, via a control device 36, which is provided with a program transmitter 37 associated with the control electrodes of the thyristors, and with which the opening and closing times of the thyristors 24 to 29 can be set (programmed), in such a manner that the welding current is single-phase and has a frequency which is three or one-and-one-half times the supply frequency.In the case of three times the supply frequency, the thyristors are opened in accordance with Fig. 2 (sections from the three-phase supply voltages R, S, T) and Fig. 3 (secondary open-circuit voltage at transformer 11 with the thyristors driven fully), the numbers specified in the halfwaves of Fig. 2 and 3 indicate the thyristors which are on. The program transmitter 37 is preferably constructed as a timing generator, known in itself, for driving thyristor circuits.
In Figs. 2 and 3 the positive and negative halfwaves of the single-phase alternating current have the same area. Of course, it is also possible to adjust the areas to be of different sizes by applying differing amounts of drive to the thyristors (phase control), which is particularly of advantage in the welding of light metals, for example in order to influence the rectifier effect. The phase control also makes it possible to adjust the current or voltage.
In Fig. 4 the primary currents in the individual primary part-coils 15, 16, 17 of the transformer are shown diagrammatically, without taking into consideration the smoothing effect of the chokes 18, 19 and 20. The numbers indicate the thyristors which are on.
The curve of the welding current produced on the secondary side of the transformer 10 is shown in Fig. 5. As can be seen from Fig. 5, each alternating current halfwave has steep zero transitions which is of advantage in giving the power source good welding characteristics. These steep zero transitions are in particular achieved by the smoothing chokes 18, 19. 20 provided, which in operation are always magnetized in the same direction by the primary currents (Fig. 4); that is, a direct current flow is applied to the chokes.
With the system described it is also advantageously possible, in open circuit, to use the appropriate phase control to switch the opencircuit voltage to the reduced open-circuit voltage prescribed for welding operation under conditions of increased electric danger, for example in narrow rooms. After ignition, the system is automatically switched to the present power value in known manner, in dependence on the current and voltage conditions in the primary and secondary power circuit of the power source which are different under open-circuit and under load conditions.
The preferred use of the power source described is for tungsten inert-gas welding (TIG welding). Of course, it can also be used in conjunction with submerged arc-welding system having high alternating welding currents, with shielded inert gas metal arc welding systems having fusible electrodes and with processes of a similar type.
Instead of thyristors serving as the controllable switches and rectifiers, it will of course be understood that other equivalent electric or electronic components can also be used. It is also possible to use two different components, each of which exercises one of the said functions (switching and rectifying), such as, for example, a diode and a switching transistor connected in series.
Claims (5)
1. A power source for arc welding, comprising a transformer and controllable rectifiers for generating an alternating single-phase welding current with a welding current frequency which is one-and-one half or three times the supply frequency, characterised in that
the secondary winding (11) of the transformer (10) is connected to the workpiece (12) and to the welding torch (13),
the primary winding (14) of the transformer (10) is provided with three delta-connected part-coils (15, 16. 17)which have identical windings,
one end (15a, 16a, 17a) of each primary part-coil (15, 16, 17) is connected to a centre tap (M) of three smoothing chokes (18, 19, 20),
the other end (15b, 16b, 17b) of each primary part-coil (15, 16, 17) is connected to one phase (R, S, T) of a three-phase network and to the one terminal (21, 22, 23) of two antiparallelconnected rectifiers (24/25, 26/27, 28/29), and
the other terminals (30/31, 32/33, 34/35) of the rectifiers (24 to 29) are connected to the start (18a, 19a, 20a) and to the end (18b, 19b, 20b) of the smoothing choke (18, 19, 20) (Fig. 1).
2. A power source according to claim 1, characterised in that the controllable rectifiers (24 to 29) are in the form of thyristors.
3. A power source according to claim 1 or claim 2, characterised in that, for driving the thyristors (24 to 29), a control device (36) is provided which has a program transmitter (37), in the form of a timing generator, for setting the opening and closing time of the thyristors (24 to 29).
4. A power source according to any one of claims 1 to 3, when applied to tungsten inert-gas arc welding.
5. A power source for arc welding, substantially as hereinbefore described with reference to, or as shown in, the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19782855662 DE2855662A1 (en) | 1978-12-22 | 1978-12-22 | POWER SOURCE FOR ARC WELDING |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2039167A true GB2039167A (en) | 1980-07-30 |
Family
ID=6058118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7943189A Withdrawn GB2039167A (en) | 1978-12-22 | 1979-12-14 | Power source for arc welding |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5586686A (en) |
| AT (1) | ATA710479A (en) |
| BR (1) | BR7908326A (en) |
| DE (1) | DE2855662A1 (en) |
| FR (1) | FR2444527A1 (en) |
| GB (1) | GB2039167A (en) |
| IT (1) | IT1126529B (en) |
| SE (1) | SE7909924L (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5388031A (en) * | 1990-06-08 | 1995-02-07 | Satoh; Ryoda | Three-phase to single-phase power supply converter for welding equipment |
| US6114655A (en) * | 1997-06-11 | 2000-09-05 | Illinois Tool Works Inc. | Method and apparatus for producing welding power |
| US6177651B1 (en) * | 1998-06-11 | 2001-01-23 | Illinois Tool Works Inc. | Method and apparatus for producing welding power |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT411444B (en) * | 2000-06-28 | 2004-01-26 | Fronius Schweissmasch Prod | WELDING MACHINE, WHICH ON ONE, TWO OR THREE-PHASE NETWORKS CAN BE OPERATED |
-
1978
- 1978-12-22 DE DE19782855662 patent/DE2855662A1/en not_active Withdrawn
-
1979
- 1979-11-05 AT AT0710479A patent/ATA710479A/en not_active Application Discontinuation
- 1979-11-30 SE SE7909924A patent/SE7909924L/en not_active Application Discontinuation
- 1979-12-07 IT IT27944/79A patent/IT1126529B/en active
- 1979-12-10 JP JP15930479A patent/JPS5586686A/en active Pending
- 1979-12-14 GB GB7943189A patent/GB2039167A/en not_active Withdrawn
- 1979-12-19 BR BR7908326A patent/BR7908326A/en unknown
- 1979-12-21 FR FR7931506A patent/FR2444527A1/en active Granted
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5388031A (en) * | 1990-06-08 | 1995-02-07 | Satoh; Ryoda | Three-phase to single-phase power supply converter for welding equipment |
| US6114655A (en) * | 1997-06-11 | 2000-09-05 | Illinois Tool Works Inc. | Method and apparatus for producing welding power |
| US6278081B1 (en) * | 1997-06-11 | 2001-08-21 | Illinois Tool Works Inc. | Method and apparatus for producing welding power |
| US6177651B1 (en) * | 1998-06-11 | 2001-01-23 | Illinois Tool Works Inc. | Method and apparatus for producing welding power |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2444527B3 (en) | 1982-02-26 |
| FR2444527A1 (en) | 1980-07-18 |
| SE7909924L (en) | 1980-06-23 |
| IT1126529B (en) | 1986-05-21 |
| BR7908326A (en) | 1980-09-16 |
| JPS5586686A (en) | 1980-06-30 |
| DE2855662A1 (en) | 1980-07-03 |
| ATA710479A (en) | 1982-07-15 |
| IT7927944A0 (en) | 1979-12-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |