US20060076329A1 - Transformer module for a welder - Google Patents

Abstract

An electric arc welder comprising a high switching frequency inverter for driving the primary of an output transformer where the output transformer has a plurality of modules forming the secondary windings of the transformer and each of the modules comprises a first coaxial set of concentric, telescoped tubes separated by a tubular insulator, a second coaxial set of concentric, telescoped conductive tubes separated by a tubular insulator wherein the sets each have an elongated central passage for accommodating the primary and a conductor connecting the tubes into a series circuit. These modules form a transformer for such welder.

Description

• The present invention relates to the art of electric arc welding and more particularly to a modular transformer operated by high frequency and having an output for welding and a module for such transformer.
INCORPORATION BY REFERENCE
• The invention relates to a module that can stand alone or be combined with similar modules to form a high frequency transformer for use in electric arc welding. The actual electrical circuit for the transformer can vary; however, a representative transformer circuit is shown in Blankenship U.S. Pat. No. 5,351,175 incorporated by reference herein as background information. The transformer module is an assembly which forms the secondary of a transformer, wherein the primary is interleaved through one or more modules. If more than one module is used, they are used in a matrix transformer. This technology is well known and is shown in Herbert U.S. Pat. No. 4,942,353 which is incorporated herein so that disclosure of the matrix transformer technology need not be repeated. In Herbert U.S. Pat. No. 5,999,078 two adjacent magnetic cores are provided with secondary windings and primary windings wherein each module includes a half turn of the secondary winding. These modules merely provide a flat conductive strip through a core to be connected as a part of a secondary winding. The primary winding is then interleaved through the modules in accordance with standard matrix transformer technology. A similar module having several turns in a given core is shown in Herbert publication No. 2002/0075119. This patent and publication are incorporated herein to show prior art technology regarding a module used for a secondary winding in a matrix type transformer. All of these patents are included as background information.
BACKGROUND OF INVENTION
• In electric arc welding it is necessary to create high currents from a power source, such as an inverter. To accomplish this objective, the inverter must be operated at a switching frequency which is quite high, such as 40 kHz so that the size of the components and the cost of the components are low. To create high currents from power sources using high switching frequencies, it is normal to merely employ an output transformer involving a primary and secondary. Consequently, the transformer has to be relatively robust in construction and capable of generating and handling high currents. Such transformers are quite expensive and bulky.
THE INVENTION
• The present invention relates to electric arc welding wherein a power source is operated at high switching frequency, such as 40 kHz. In accordance with the invention, the output transformer of this electric arc welder is a coax configuration where the secondary windings of the output transformer are constructed so the primary winding can be passed through one or more module to produce a highly coupled transformer with a very compact construction and enhanced heat dissipation characteristics. The invention is directed to a novel and unique module construction allowing a single module or multiple modules to be applied to an electric arc welder. A single or multiple modules are used dependent on the power output requirements.
• The module of the present invention comprises a first coaxial set of concentric, telescoped conductive tubes separated by a tubular insulator, a second coaxial set of concentric telescoped conductive tubes separated by a tubular insulator and a magnetic core around each of the tube sets so that each set of conductive tubes has an elongated central passage for accommodating at least one primary winding. This module includes a conductor connecting the tubes of the sets into a series circuit so the output of each module is directed to a rectifier for conversion into a portion of the output current necessary for electric arc welding. The current from all of the modules are summed to obtain a welding current.
• By using this unique module design, the module can be used by itself or as a plurality of modules can be interleaved with one or more primaries to create a welding current having an output capability in excess of 1000 amperes.
• The primary object of the present invention is the provision of a modular transformer for an electric arc welder.
• A further object of the present invention is the provision of a module, as defined above, which module involves parallel coaxial tubes connected in series and defining central passages for a primary or primaries of the output transformer of a power source used in electric arc welding.
• Yet another object of the present invention is the provision of a module, as defined above, which module employs two concentric conductive tubes connected in series in a single module to define a multi-turn secondary winding for an output transformer of an electric arc welder.
• A further object of the present invention is the provision of a matrix transformer at the output of a power source used in electric arc welding.
• These and other objects and advantages will become apparent from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
• FIG. 1 is a pictorial view of a module constructed in accordance with the present invention;
• FIG. 2 is a side elevational view of the module showing in partial cross-section one side of the concentric tube construction;
• FIG. 3 is a schematic wiring diagram illustrating the current flow in a module as shown inFIGS. 1 and 2;
• FIG. 4 is a wiring diagram of the module shown inFIGS. 1-3 in conjunction with a single primary winding interleaved through the passages of the parallel concentric tube module;
• FIG. 5 is a schematic wiring diagram similar toFIG. 3 illustrating a modified module utilizing two parallel tubes with a full wave output rectifier;
• FIG. 6 is a wiring diagram showing three modules as illustrated inFIGS. 1-3 connected as the output of the power transformer in an electric arc welder;
• FIG. 7 is a schematic wiring diagram of the high switching speed inverter used for the primary winding and/or windings that are interleaved in the modules schematically represented inFIG. 6 and shown in detail inFIGS. 1-3 and inFIG. 8; and,
• FIG. 8 is a pictorial view of three modules connected as shown inFIG. 6 utilizing a plurality of modules as disclosed inFIGS. 1-3.
PREFERRED EMBODIMENT
• A novel secondary module constitutes the basic building block of the present invention. The preferred embodiment is shown inFIGS. 1 and 2 wherein secondary module A is constructed to receive one or more primary windings P through a pair of parallel cylindrical openings designed to accommodate one or more primary windings in parallel relationship. Module A is used both as a single secondary winding, or as one of several modules in a matrix transformer where primary winding P is interleaved through two or more modules A as will be explained later. In the preferred embodiment, module A is formed from afirst assembly10 with afirst tube12 terminating in alower tab14 having aconnector hole16.Central passage18 intube12 is used as the primary winding passage when module A includes only thefirst assembly10. As will be explained, the preferred embodiment has two assemblies formed by telescoping two coaxial conductive tubes usually formed from copper and telescoped around each other.Second tube20 offirst assembly10 includes aterminal tab22 with alower connector hole24 and has a centralcylindrical passage26. To fixtube12 with respect totube20, so the tubes are in parallel and in spaced relationship, afirst jumper strap30 is provided. Two space holes instrap30 surround the first end oftubes10,20 soweld joints32 fix the tubes into the holes. As so far described, the jumper strap is at one end of the tubes and the tubes are parallel and spaced with the second ends having protrudingtabs16,22, respectively. As will be explained later, onlyassembly10 may be used; however, the preferred embodiment involves a coaxial relationship involving asecond assembly40 essentially the same asassembly10 with tubes having lesser diameter so that they telescope intotubes12,20.Assembly40 includesthird tube42 having alower tab44 with aconnector hole46 and acentral passage48 to accommodate winding P. Afourth tube50 has alower tab52 with aconnector hole54 so that the third and fourth tube can be joined by asecond jumper strap60 provided with spaced openings surrounding the top or first end oftubes42,50.Weld joint62 around the tubes joins the tubes into the holes ofjumper strap60. This second assembly is quite similar to the first assembly except the diameters oftubes42,50 are substantially less than the diameters oftubes12,20. In the cylindrical gap between the tubes, a Nomex insulator sleeve orcylinder70,72 is provided. These cylindrical insulator sleeves electrically isolate the coaxial tubes forming the basic components of module A.Plastic end caps80,82 are provided with two transversely spacedrecesses84 incap80 and two spacedrecesses86 incap82. Only one of therecesses84,86 is illustrated inFIG. 2. The other recesses are the same and need not be illustrated. The construction of the left coaxial assembly of module A is essentially the same as the construction of the right coaxial assembly as shown in cross-section inFIG. 2. As illustrated, between cap recesses84,86 there are provided a plurality of ferrite donut-shaped rings or magnetic cores90-98. To center the cores there are provided a number ofsilicon washers100 sobolts110 havingheads112 clamp the end caps together. This action holds the spaced rings around the coaxial tubes ofmodule A. Assemblies10,40 with the coaxial tubes are held onto module A by an upperplastic nose120 having an arcuateprimary winding guide122. The nose is held ontoend plate82 by transversely spacedbolts124.Nose120 includes laterally spacedslots126,128 so that the nose can be moved from one edge ofassemblies10,40 to the center position by riding on spaced jumper straps30,60. When in the center of the module, the plastic nose is bolted to endcap82. This clampsassemblies10,40 onto module A in the position shown inFIG. 2 and holdsstraps30,60 in spaced relationship. The coaxial tubes are aligned byholes80a,82aconcentric withcylindrical recesses84,86 inend caps80,82, respectively. Two of these holes are located in each of the end caps.Washers100 center the coaxial tubes in the cylinder formed by core rings90-98.
• In the preferred embodiments, module A is connected as a secondary for a high frequency transformer driven by a primary from an inverter. This electrical arrangement involves connectingassemblies10,40 in series by acenter tap connector130 havingholes132,134 and136. Arivet140 connectshole132 withtab52, whilerivet142 connectshole136 withtab14. To stabilizecenter tap130, the ends of the tap are provided withcylindrical wings144,146, best shown inFIG. 2. As shown inFIG. 3, module A is connected to rectifier150 havingdiodes152,154 and anoutput terminal156. By this arrangement, the single coaxial module allows primary winding or windings P to be leaved throughcylindrical passages48,56 so the module is a secondary of a high frequency transformer. This is a normal use of the present invention when employed for an electric arc welder. A simplified wiring diagram of the embodiment is illustrated inFIG. 4 to show primary winding P andsecondary windings12/20 and42/50.
• In accordance with an aspect of the invention, module A′ shown inFIG. 5 includesonly tube assembly10 with onlyconductive tubes12,20 that define terminal ends16,24. These terminals are connected across afull wave rectifier160 havingoutput terminals162,164.Tubes12,20 could be a single tube; however, in the invention two tubes are used to minimize inductance so the primary winding from the inverter is leaved aroundjumper30 through center windingaccommodating openings18,26.
• A plurality of modules A are arranged to provide a high frequency transformer for a welder represented by electrode E and workpiece W inFIG. 6. This matrix transformer concept is illustrated schematically inFIGS. 6-8 wherein modules A1, A2 and A3 are joined together byend straps190,192 in one end of the multiple module assembly shown inFIG. 8 and endstraps194,196 on the other end. Bolts clamp a frame around modules A1, A2 and A3 to assemble them into alignment, as shown inFIG. 8 wherein each set ofpassages48,56 is in parallel and are aligned in side-by-side relationship. The wiring diagram for the assembly shown inFIG. 8 is illustrated inFIG. 6 whereinterminals156 are connected in parallel atterminal170 andcenter tap148 is connected in parallel atterminal172. The primary windings from one or more inverters are shown schematically in the wiring diagram ofFIG. 7.Inverter200 creates an AC current in primary P1. In a like manner,inverter202 provides an AC current in primary P2. These two primaries are interleaved together through modules A1, A2 and A3. In practice, two primary windings are used in the matrix transformer ofFIG. 8; however, a single winding is also used in this type of matrix transformer.FIGS. 6-8 merely illustrate that the coaxial secondary transformer module A ofFIGS. 1-3 can either be used as a single secondary winding or as parallel secondary windings in a matrix transformer. Other arrangements use module A as a secondary winding for a transformer between an inverter and a welding operation. The tubular, coaxial conductors disclosed in module A are sometimes replaced by an elongated ribbon helix around the center axis of the individual tubes. Such helix configuration still provides the coaxial relationship between the concentric tubes. The term “tube” defines a continuous tube conductor, as so far described, or the helix tube as used in the alternative embodiment.

Claims (26)

1. (canceled)

2. The high speed frequency transformer ofclaim 36 wherein each of said magnetic cores comprises a plurality of doughnut-shaped rings around one of said tubes.

3-4. (canceled)

5. The high frequency transformer ofclaim 36 wherein each of said first and second modules further includes a conductive assembly comprising a third conductive tube with first and second ends, a fourth conductive tube with first and second ends and a second jumper strap joining said first ends of said third and fourth tubes into a parallel relationship to each other and to said first and second tubes; said third and fourth parallel tubes being telescoped into said passages of said first and second tubes, respectively, and having elongated passages for accommodating said primary winding or windings with said first and second jumper strap spaced from each other; a first tubular insulator between said first and third tubes; a second tubular insulator between said second and fourth tubes; and a center tap connector joining said conductive assembly to a second end of one of said first and second tubes to form said tubes into a series circuit.

6. A module as defined inclaim 5 wherein said second end of one of said first and second tubes and one end of one of said third and fourth tubes are connected to a rectifier.

7-21. (canceled)

22. An electric arc welder comprising an output transformer and a high switching frequency inverter for driving the primary of the output transformer, said output transformer having a plurality of modules forming secondary windings, each of said modules comprising a first coaxial set of concentric, telescoped tubes separated by a tubular insulator, a second coaxial set of concentric, telescoped conductive tubes separated by a tubular insulator, said sets each accommodating said primary, and a conductor connecting said tubes into a series circuit.

23. A welder as defined inclaim 22 wherein said tubes of said modules are each connected to a rectifier to create a positive and negative current output and a circuit connecting said outputs in parallel.

24. (canceled)

25. A power source as defined inclaim 44 wherein said tubes of said modules are each connected to a rectifier to create a positive and negative current output and a circuit connecting said outputs in parallel.

26. A power source as defined inclaim 25 wherein said tubes of said modules are formed by an elongated ribbon helixed around a central axis of said tube.

27-34. (canceled)

35. A high frequency transformer of an electric arc welder, comprising:

a first module having a first module secondary winding section;

a second module having a second module secondary winding section, said first module secondary winding section interconnected with said second module secondary winding section; and

a primary winding through each of said first and second modules.

36. The high frequency transformer ofclaim 35 wherein each of said first and second modules includes:

a first conductive tube with first and second ends and a central elongated passage;

a generally parallel second conductive tube with first and second ends and a central elongated passage; and

a magnetic core surrounding each of said first and second tubes, wherein said primary winding is accommodated in said central elongated passages of said first and second tubes, said first ends of said tubes are joined together by a jumper strap, and a circuit forming connector is disposed at said second ends of said tubes.

37. The high frequency transformer ofclaim 35 further including a third module having a third module secondary winding section, said winding sections of said first, second and third modules interconnected and said primary winding through each of said first, second and third modules.

38. The high frequency transformer ofclaim 35 wherein each of said modules has a given current capacity and a total output welding current is the sum of the given current capacities of each of said first and second modules.

39. The high frequency transformer ofclaim 38 wherein said total output exceeds about 1,000 amperes.

40. The high frequency transformer ofclaim 38 wherein the given current capacity of each of said first and second modules is approximately the same.

41. The high frequency transformer ofclaim 35 wherein said first and second modules are readily removable from one another.

42. The high frequency transformer ofclaim 35 wherein the primary is driven by a high frequency inverter.

43. The welder ofclaim 22 wherein said sets of tubes each have an elongated passage accommodating said primary.

44. The welder ofclaim 22 wherein each of said plurality of modules is readily removable from said output transformer.

45. A power source for electric arc welding, said power source includes a high switching speed inverter for driving the primary of an output transformer with AC primary current, said output transformer having a number of modules each with a given current capacity forming the secondary winding of the output transformer, said modules connected in parallel with the total output welding current being the sum of the current capacities of said separate modules and able to exceed about 1,000 amperes.

46. A power source as defined inclaim 45 wherein said given current capacities are the same.

47. A power source as defined inclaim 45 wherein each of said number of modules comprises a first conductive tube with first and second ends; a generally parallel closely adjacent second conductive tube with first and second ends, said tubes each having a central elongated passage accommodating one or more primary windings; a magnetic core surrounding each of said tubes; a jumper strap joining said first ends of said tubes; and, a circuit forming connector at said second ends of said tubes.

48. A power source as defined inclaim 47 wherein each of said number of modules includes a conductive assembly comprising a third conductive tube with first and second ends, a fourth conductive tube with first and second ends and a second jumper strap joining said first ends of said third and fourth tubes into a parallel relationship to each other and to said first and second tubes; said third and fourth parallel tubes being telescoped into said passages of said first and second tubes, respectively, and having elongated passages accommodating said primary winding or windings with said first and second jumper strap spaced from each other; a first tubular insulator between said first and third tubes; a second tubular insulator between said second and fourth tubes; and a center tap connector joining said conductive assembly to a second end of one of said first and second tubes to form said tubes into a series circuit.

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