HIGH-FLOW TRANSFORMER, TRANSFORMER ELEMENT, CONTACT PLATE AND SECONDARY WINDING, AND METHOD FOR PROD

专利摘要:
The invention relates to a high-current transformer (12), in particular for a current source (10) for providing a welding current of a resistance welding device (1), with at least one primary winding (13) and at least one secondary winding (14) with center tap, and a transformer element, a contact plate ( 29) and a secondary winding (14) for such a high-current transformer (12) and a method for its production. To reduce the losses and improve the efficiency, at least four contacts (20, 21, 22, 23) are provided to form a multipoint contact, which contacts (20, 21, 22, 23) are formed by four contact surfaces, within which the at least one primary winding (13) and the at least one secondary winding (14) are arranged in a series / parallel circuit.
公开号:AT512064A1
申请号:T1601/2011
申请日:2011-10-31
公开日:2013-05-15
发明作者:Bernhard Artelsmair；Christoph Schultschik；Johannes Neuboeck；Stefan Wolfsgruber
申请人:Fronius Int Gmbh；
IPC主号:

专利说明:

The invention relates to a high current transformer, in particular for a current source for providing a welding current of a resistance welding device, with at least one primary winding and at least one secondary winding with center tap.
The invention further relates to a transformer element for * a high-current transformer having at least one primary winding and at least one secondary winding with center tap.
The invention also relates to a contact plate for a high-current transformer having at least one primary winding and at least one secondary winding with center tap, and a secondary winding for a high-current transformer, in particular for a current source for providing the welding current for a resistance welding device.
Finally, the invention relates to a method for producing a high-current transformer having at least one primary winding and at least one secondary winding with surfaces for contacting.
The present invention relates mainly, but not exclusively, to high current transformers and their components for resistance welding devices, in particular spot welding devices in which particularly high DC currents on the order of a few kA occur. High-current transformers for other devices, in which such high DC currents are used, are included in the subject matter of the present patent application. Examples of such devices are battery chargers, particle accelerators, devices for electroplating or the like. WO 2007/041729 Al describes, for example, a battery charger and a current transformer for producing a correspondingly high direct current.
In resistance welding devices, the required high DC currents are provided by means of corresponding high current transformers and rectifiers. Due to the high currents occurring diode rectifier are disadvantageous because of the relatively high losses, which is why mainly active rectifier with switching elements, which are formed by corresponding transistors, are used. But also resistance welding devices with active rectifiers, such as synchronous rectifiers, have relatively high losses and thus relatively low efficiencies. As in the prior art by the usual separate structure, such as high current transformer and rectification, considerable line lengths and thus line losses incurred, a very poor efficiency due to the high currents is caused.
For example, DE 10 2007 042 771 B3 describes a method for operating the power supply of a resistance welding device using a synchronous rectifier, by which the power loss can be reduced and the efficiency can be improved.
In production lines in the automotive industry, a variety of spot welding devices (often several 100 to 1000 individual devices) are used to make various connections to the body and the chassis of the vehicle to be manufactured. Since the individual spot welding devices already cause very high losses through the high-current transformers and lines and switching elements, the total losses occurring in such production lines are in enormously high dimensions, for example between 1 MW and 50 MW. Since the losses are mainly reflected in the form of heat loss, measures are again taken to dissipate heat, whereby the entire energy balance is further deteriorated.
A further disadvantage results from the fact that very high connection capacities of the supply network are required by the high losses for such systems, which results in very high costs for the production, commissioning and operation of such a system.
For the production of a single welding point with a welding current of 20kA, according to the state of the art, from today's point of view, for example, a connection power of the supply network of up to 150 kW is required, whereby at the mentioned welding current
Losses of up to 135kW result, resulting in a very poor efficiency of only about 10% is achieved.
The object of the present invention is therefore to provide a high-current transformer, a transformer element, a contact plate, a secondary winding for such a high-current transformer and a method for producing such a high-current transformer, through which the losses can be reduced and the energy balance and the efficiency can be improved , Disadvantages of known devices and methods should be reduced or avoided.
The object of the invention is achieved by an above-mentioned high-current transformer, in particular for a current source for providing a welding current of a resistance welding device in which at least four contacts are provided to form a Mehrpunktkontaktierung, which contacts are formed by four contact surfaces, within which the at least one primary winding and the at least one secondary winding are arranged in a series / parallel circuit. By such Mehrpunktkontaktierung lines that are usually required for connecting the secondary side of the high-current transformer to the consumer, can be saved or their length can be reduced and thus the Ohm'sehen losses as well as the contact transition losses can be reduced. Thus, the shortest possible lines with the largest possible cross sections can be used. Another advantage is that the losses, in particular contact contact resistance losses, are reduced as a result of such contacting. Due to the at least four contacts of the current to be transmitted can be halved, whereby a reduction of the transition losses is effected. This also ensures that the active contact surfaces can be significantly increased and thus in turn the contact resistance can be reduced. By means of such a high-current transformer according to the invention, it is achieved that at a current of, for example, 20 kA, the connected load must now be only 75 kW (compared to 150 kW in the case of comparable prior art devices), with losses of 60 kW occurring the efficiency can be achieved to about 20% and more.
To achieve the required transmission ratio of the high-current transformer for generating the high secondary current, this has according to a further feature of the invention a plurality, preferably at least 10, series-connected primary windings and a plurality, preferably at least 10, parallel-connected secondary windings with center tap. The primary current flows through the series-connected primary windings of the Höchstroratransformators, whereas the relatively high secondary-side current to the plurality, preferably at least 10, parallel-connected secondary windings is divided. The secondary-side partial currents are supplied to the corresponding switching elements of the synchronous rectifier. By such a division results in spite of low primary and secondary-sided numbers of turns, a correspondingly high transmission ratio. This construction, in contrast to conventional high-current transformers, requires lower numbers of turns on the primary side, which can reduce the length of the primary winding and thereby reduce the ohmic losses. Due to the reduced number of turns and the resulting reduction in the line length, the system-typical stray inductance of the high-current transformer is again reduced, as a result of which the high-current transformer can be operated with higher switching frequencies, for example 10 kHz. The higher switching frequencies in turn cause a reduction in the size and weight of the high-current transformer and thus advantageous installation options. Thus, the high current transformer can be positioned as close as possible to the load, for example the electrodes of a resistance welding device. Thus, the payload of a welding robot can also be reduced due to the low weight of the high current transformer, so that a small, cheaper robot can cope.
The transmission ratio of the high current transformer is 10 to 1000, preferably at least 100, to ensure the generation of the high secondary side current.
A particularly advantageous construction of the high-current transformer can be achieved in that the high-current transformer has an I-shaped carrier of electrically conductive material, in whose recesses in each case at least one ring core is arranged, wherein in each case one terminal of each secondary winding directly with an inner surface and the contact plate of the I-beam is contacted, and the outer surfaces of the I-beam forming the two first contacts of the high-current transformer. The I-beam thus forms the basis of the high-current transformer, around which the secondary windings are arranged such that no connecting lines are required. The outer surfaces of the I-beam represent the two first contacts of the high-current transformer, which are connected directly, ie, without line, with the respective consumer. A Pplatz saving arrangement is achieved in that the ring cores are not circular, but oval. Preferably closed ring cores are used. By this construction, the series / parallel connection of the primary windings and secondary windings is achieved, through which the transmission ratio of the high current transformer for the high DC to be provided can be achieved at the same low turn numbers of the primary windings and secondary windings. Such a structure pays off in particular if at least three secondary windings connected in parallel are arranged on each side of the I-beam.
Advantageously, the center tap of the at least one secondary winding of the high-current transformer is conductively connected to the I-beam. Thus, corresponding lines between the individual components can be omitted. Due to the direct connection of the secondary winding to the midpoint of the I-beam, a substantial enlargement of the connection area is achieved, and thus transition losses and losses in the line can be reduced again.
In the above construction of the I-beam high-current transformer, the at least one primary winding of the high-current transformer is arranged to extend through the at least one ring core, in particular the ring cores arranged symmetrically on both sides in the recesses of the I-beam. By such an arrangement of the primary winding, an optimal magnetic coupling to the secondary windings can be achieved.
As already mentioned above, the secondary windings are electrically connected to each other via the I-beam of the high-current transformer. The respective other terminals of each secondary winding are preferably connected via a synchronous rectifier and a drive circuit directly to a respective contact plate made of electrically conductive material, which contact plates are disposed over the recesses of the I-beam and the secondary windings arranged therein, wherein the outer surfaces of these contact plates, the two other Make contacts of the power source.
The terminals of the at least one primary winding of the high-current transformer are led out according to a further feature of the invention via at least one opening to an outer surface of the I-beam. From there, the terminals of the primary winding of the high-current transformer can be connected to the corresponding voltage source or a power unit.
An advantageous embodiment of the high-current transformer results from the fact that in each case a secondary winding with center tap is formed by two mutually insulated sheets of electrically conductive material having a substantially S-shaped, opposite course around the cross section of a toroidal core and through the toroidal core, wherein the outer surfaces of the Sheets form the contacts for connection to the switching elements of the synchronous rectifier or the I-beam and thus the electrodes of a resistance welding device. This results in a very space-saving and compact design. At the same time very large contact surfaces are available for the connection of the secondary winding to the center or central web of the I-beam and the switching elements of the synchronous rectifier, in order to ensure the high current flow with as few losses.
The sheets for forming the secondary winding of the high current transformer are insulated from each other by an insulating layer such as a paper layer. As a result, two secondary windings can be arranged on a toroidal core and thus the
Size, weight and losses are significantly reduced. By this arrangement, a center rectifier is realized on the secondary side, wherein the I-beam with the connected, in particular soldered one end of the secondary windings form the center.
The I-beam and the contact plates of the high-current transformer preferably form a cubic or cuboid unit, wherein an electrical insulation is arranged between the I-beam and the contact plates. The two outer surfaces of the I-beam form the two first contacts and the two outer surfaces of the contact plates to the two 90 ° angularly offset two further contacts of the power source. If further components of a current source for providing a direct current, such as a synchronous Gleichrischter, a drive circuit, supply circuits for the synchronous rectifier and the drive circuit are integrated in this cube or cuboid unit, a self-sufficient unit is formed, which input side only with the power part and the output side must be connected to the respective consumer. Usual lines between the individual circuits of a power source can be omitted or at least significantly reduced in length.
If cover plates are arranged on the end faces of the I-beam, a more stable unit of the high-current transformer can be formed in cube or cuboid shape.
If the cover plates are also formed of electrically conductive material and can be screwed to the contact plates, an electrical connection of the contact plates can be achieved. As a result, a separate electrical line, which electrically connects the two contact plates to one another, is dispensed with in order to produce a voltage or potential equalization and thus to avoid an asymmetry of the two contact plates. Thus, the electrical connection of the two contact plates of the symmetrical arrangement of the high-current transformer or of a current source for providing the direct current is produced via the cover plates.
The cover plates are opposite the I-beam of the high-current trans- 8 * * * * fr * * • • fr «fr» «· fr • fr × fr fr fr * fr # fr fr *······ fr «« · Formators electrically insulated.
The I-beam and / or the contact plates and / or the cover plates and / or the plates for forming the secondary winding of the high-current transformer is preferably made of copper or a copper alloy, preferably with a silver coating. Copper or copper alloys have optimal electrical properties and show good thermal conductivity, whereby occurring heat losses can be dissipated more quickly. The silver coating prevents oxidation of the copper or copper alloy. Instead of copper or copper alloys are also aluminum or aluminum alloys in question, which have a weight advantage over copper, although the corrosion resistance is not so high. Instead of a silver coating, a coating of tin and other materials or their compounds or layers is possible.
On the outer surfaces of the I-beam and the outer surfaces of the contact plates connecting means, preferably bores with a thread for receiving screws may be arranged. Both the mechanical and electrical connection of the power source to the components of the consumer, for example the gun arms of a resistance welding device, can be produced via these connecting devices. In addition, various other elements can be attached to the outer surfaces of the I-beam or the contact plates via such connecting means.
According to a further feature of the invention, a current transformer for measuring the current through this secondary winding is arranged in each case on the first secondary winding of each side of the I-beam, which current transformers are connected to a drive circuit. The current transformer is used to measure the secondary-side current, as a result of which the switching elements of a synchronous rectifier are actuated in order to minimize the forward losses and the switching losses. In a symmetrical structure of the high-current transformer or a current source containing the high-current transformer with an I-beam as the basis of the high-current transformer are on both sides of the I-beam secondary 9th
Windings and also arranged on both sides of the current transformers. The current transformers are each contacted directly with a control circuit arranged next to them and connected via corresponding lines to the respective opposite drive circuit. It is essential here that due to the parallel connection of the secondary windings in each winding always the same current flows and thus the current flow must be tapped only by a secondary winding in order to zurücksch-let to the entire current flow can. In a parallel circuit of ten secondary windings, therefore, only one-tenth of the total secondary current flow is measured by the current transformers, which can therefore be dimensioned much smaller. This in turn achieves a reduction in the size of the high-current transformer or the current source.
To prevent interference by external magnetic fields, each current transformer is shielded by a housing and preferably a shield of magnetically conductive material. Ferrites are particularly suitable as materials for such shieldings,
To dissipate the resulting heat loss in the power source of the resistance welding device preferably channels for guiding a cooling fluid are arranged in the I-beam and the contact plates. In particular, water is suitable as the cooling fluid, but gaseous cooling agents can also be conveyed through the cooling channels and the heat of dissipation removed therefrom.
A preferred embodiment of the cooling channels is provided in that two inlets for supplying the cooling fluid and an outlet for discharging the cooling fluid are arranged on an outer surface of the I-beam, wherein the cooling channels from each inlet to the contact plates and via the I-beam to the outlet are arranged running. The cross section of the outlet corresponds to the sum of the cross sections of all inlets. This course of the cooling channels ensures that first the contact plates, on which the boards of a synchronous rectifier and a drive circuit with correspondingly sensitive components are arranged, are cooled with the correspondingly cool cooling fluid. Thereafter, the less sensitive components, in particular the I-beam, which is in communication with the secondary windings, are cooled.
Preferably, a synchronous rectifier with switching elements and a circuit for driving the switching elements of the synchronous rectifier is connected to the at least one secondary winding of the high-current transformer. By this preferably direct, so wireless, connection between the high current transformer and a synchronous rectifier and the drive circuit Ohm'sehe losses and further losses can be prevented by such lines. Also, any supply circuits for the synchronous rectifier and the drive circuit are preferably integrated in the high-current transformer. It is preferred for the supply of
High current transformer positioned as close as possible to the power unit in order to achieve the shortest possible connecting lines and thus the lowest possible line losses and Leitungsinduktivitäten.
In order to minimize the on-state losses and switching losses of the switching elements of the synchronous rectifier, the driving circuit for activating the switching elements of the synchronous rectifier is formed at a preset timing before reaching the zero-crossing of the current in the secondary winding. By this preset timing, the delay that occurs from detecting the zero crossing of the secondary side current until the activation of the respective switching elements can be compensated. That is, the on and off timing of the switching elements of the synchronous rectifier is not set with the zero crossing of the secondary side current but with reaching a defined on and off threshold. The switch-on and switch-off threshold is defined according to the expected switching delays. At best, the switch-on and switch-off thresholds can be made adjustable in order to be able to reduce the losses even more. For example, in a 20kA high current transformer, the switching time 100ns may be set before the zero crossing, so that all components, in particular the switching elements of the synchronous rectifier, must be switched within this period of time.
The switching elements of the synchronous rectifier are preferably conductively connected to the at least one secondary winding of the high-current transformer.
The drive circuit and the synchronous rectifier are preferably arranged on at least one circuit board, which circuit board is arranged on the inner surface of at least one contact plate. By this arrangement, the drive circuit and the synchronous rectifier on the inside of at least one contact plate, a direct, or without wires, contacting the terminals of the secondary windings with the switching elements of the synchronous rectifier and also a direct, so wireless, contacting the outputs of the synchronous rectifier can be achieved with the contact plate , Preferably, the high-current transformer or a current source containing the high-current transformer for providing a direct current is constructed symmetrically, on either side of the symmetrically arranged secondary windings each having a circuit board with a part of the synchronous rectifier and the drive circuit is arranged below each contact plate.
Each board of the synchronous rectifier and the Ansteuerschal-device preferably has openings over which the switching elements are arranged, and the inner surface of the contact plates have at the locations of the openings in the board of the synchronous rectifier bulges, in particular crenellated protrusions, so that the switching elements can be contacted via the projecting through the openings of the board protrusions on the inner surface of the contact plates without wires. In this way can be dispensed with connecting lines between the switching elements of the synchronous rectifier and the contact plate, which on the one hand, the Ohm'sehen losses can be reduced and on the other hand, the thermal transition between the switching elements and the contact plates can be improved. Finally, the production cost is reduced, since no connecting lines must be laid and connected, but the switching elements connected directly to the bulges, preferably soldered. Also, a simple positioning of the board can be made possible on the bulges and thus the production can be substantially simplified. 12 * I * t * »* * * *« «4 * ** * * * * * * *« *· * · Φ «*
Another advantage is an embodiment in which the source terminals of the switching elements formed by field effect transistors via the bulges, in particular crenellated bulges, are electrically and thermally connected directly to the contact plate, since in turn the corresponding lines can be avoided.
Each board is preferably arranged to form the necessary electrical insulation between the I-beam and the contact plates. In this way it is not necessary to provide a separate electrical insulation between the I-beam and the contact plates.
Solved object of the invention is also achieved by a transformer element for a high-current transformer described above with an I-shaped carrier made of electrically conductive material whose recesses for receiving at least one ring core is arranged with a secondary winding arranged thereon, and its opposite inner surface (s) for direct contacting each one terminal of each secondary winding is formed. The I-beam thus forms the basis of a high-current transformer, around which the secondary windings are arranged such that no connecting lines are required. The outer surfaces of the I-beam represent the two first contact surfaces, which are connected directly, ie, without wires, with corresponding components. A space-saving arrangement is achieved in that the toroidal cores are not circular, but oval. Thus, a positioning between the contacts of the I-beam is possible. Preferably closed ring cores are used. By this construction, the series / parallel connection of the primary windings and secondary windings is achieved, through which the transmission ratio of the high current transformer for the high DC to be provided can be achieved at the same low turn numbers of the primary windings and secondary windings. Such a structure pays off in particular if at least three secondary windings connected in parallel are arranged on each side of the I-beam. • f ····· 13 Φ · · · t · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · «
At least one opening for guiding the terminals of the at least one primary winding is provided on an outer surface of the I-beam. Through this opening, the terminals of the primary winding of the high-current transformer can be passed and connected to a corresponding voltage source or a power unit.
The I-beam is preferably formed of copper or a copper alloy, preferably with a silver coating. Copper or copper alloys have optimal electrical properties and show good thermal conductivity, whereby occurring heat losses can be dissipated more quickly. The silver coating prevents oxidation of the copper or copper alloy. Instead of copper or copper alloys are also aluminum or aluminum alloys in question, which have a weight advantage over copper, although the corrosion resistance is not so high. Instead of a silver coating, a coating of tin and other materials or their compounds or layers is possible.
On the outer surfaces of the I-beam connecting means, preferably bores with a thread for receiving screws, can be arranged. Both mechanical and electrical connections can be made via these connecting devices. In addition, various other elements can be attached to the outer surfaces of the I-beam via such connecting means.
To dissipate the heat loss in the high-current transformer, channels for guiding a cooling fluid are preferably arranged in the I-beam. In particular, water as well as a gaseous coolant can be conveyed through the cooling channels as the cooling fluid, and the heat loss can be dissipated via this.
In this case, two inlets for supplying the cooling fluid and one outlet for discharging the cooling fluid are preferably arranged on an outer surface of the I-beam. The cross section of the outlet corresponds to the sum of the cross sections of all inlets. By a corresponding course of the cooling channels, it is achieved that first the more sensitive areas are filled with the cold cooling fluid. Afterwards, the less sensitive components are cooled.
Solved object of the invention is also provided by a contact plate for an above-mentioned high current transformer, on one side bulges, in particular crenellated bulges, are provided for receiving a circuit board and for direct contact with switching elements. This allows a secure connection of the board with the contact surface. At the same time can be done by the formation of the bulges exact positioning of the board, since the board has corresponding openings. By the bulges is also achieved that they protrude through openings in the board and thus contacted with arranged on the opposite side of the board switching elements, in particular can be soldered.
On the at least one circuit board is preferably arranged a synchronous rectifier and a drive circuit and optionally a supply circuit for autonomous operation of the high-current transformer. As a result, no more control lines are needed and it is thus the handling much easier.
The bulges are preferably designed for the non-conducting contact of the switching elements of the synchronous rectifier by the bulges are arranged in accordance with openings provided on the board, so that the arranged over the openings switching elements of the synchronous rectifier can be contacted. About the bulges switching elements of a synchronous rectifier can be contacted without wires. In this way can be dispensed with connecting lines between the switching elements of the synchronous rectifier and the contact plate, which on the one hand, the Ohm'sehen losses can be reduced and on the other hand, the thermal transition between the switching elements and the contact plates can be improved. Finally, the production cost is reduced, since no connecting lines must be laid and connected, but the switching elements connected directly to the bulges, preferably soldered. As a result, an automated production is possible. 15 * * * ············································································································································································································ · · »+ ·· ··· * Μ ·
It is advantageous if the switching elements are soldered directly to the bulges, as this robotic or automated assembly and soldering is possible. Instead of the preferred direct connection by soldering and short connecting wires, so-called bonding wires, can be provided.
The contact plate is preferably formed of copper or a copper alloy, preferably with a silver coating. Copper or copper alloys have optimal electrical properties and show good thermal conductivity, whereby occurring heat losses can be dissipated more quickly. The silver coating prevents oxidation of the copper or copper alloy. Instead of copper or copper alloys are also aluminum or aluminum alloys in question, which have a weight advantage over copper, although the corrosion resistance is not so high. Instead of a silver coating, a coating of tin and other materials or their compounds or layers is possible.
On the outer surfaces of the contact plate connecting means, preferably bores with a thread for receiving screws, can be arranged. Both mechanical and electrical connections can be made via these connecting devices. In addition, various other elements can be attached to the outer surfaces of the contact plate via such connecting means.
If several bulges are arranged side by side on the contact plate, a plurality of switching elements can be contacted in parallel accordingly. By such a parallel connection, the on-resistance of the active rectifier can be reduced. Furthermore, it is achieved by the parallel connection of the switching elements that with a smaller dimensioning of the switching elements, a higher switching current or welding current can be switched. It is essential here that, for several, in particular ten, switching elements connected in parallel, the line length is halved, for example by control circuits arranged laterally on both sides, and thus a much faster and more symmetrical activation and switching-through of the 16 16 ·····································································.
• * * »» «» »* I • *» · · · · · · * * * * * * * * · · · · * * * * * *·· fl * ff Φ ···
Switching elements is achieved. This also ensures that the switching points of the individual switching elements is approximately identical. For this purpose, it is possible, for example, that in the center of a further gate drive is arranged to achieve even faster switching operations.
However, it is also advantageous if in a row several, in particular ten, bulges for correspondingly parallel switching elements and a plurality, in particular ten, rows of bulges are arranged one above the other. As a result, as many switching elements can be arranged on a small area, whereby a much higher current can be switched or smaller dimensioned switching elements can be used.
The object of the invention is also achieved by a secondary winding for a high-current transformer mentioned above, in which a sheet of electrically conductive material is arranged with a substantially S-shaped profile around the cross section of a toroidal core and through the ring core, wherein the outer surfaces of the sheets contacts or Make connections. Thus, a very compact construction is achieved, which can be easily integrated in a transformer element, for example in the form of an I-beam, a high-current transformer. In addition, it is achieved that the contacts of the windings are formed over a large area, so that a secure conduction-free connection with one or more switching elements and the center of the I-beam is ensured. These compounds are preferably by soldering.
However, it is also advantageous if a further metal sheet is arranged on the toroidal core to form a further secondary winding, whereby two mutually insulated sheets of electrically conductive material with substantially S-shaped, opposite course around the cross section of the toroidal core are provided, wherein the outer Surfaces of the sheets form contacts. Thus, in a simple manner, the number of secondary turns in a high current transformer can be doubled. Thus, a mid-point circuit (rectification) is achieved, wherein the I-beam represents the center. 17 i «·· ♦
The sheets are preferably insulated from each other by an insulating layer, for example a paper insulation. As a result, two secondary windings can be arranged on a toroidal core and thus the size, the weight and the losses are substantially reduced. By this arrangement, a center rectifier is realized on the secondary side, wherein the I-beam with the connected, in particular soldered one end of the secondary windings form the center.
The sheets are preferably formed of copper or a copper alloy, preferably with a silver coating. Copper or copper alloys have optimal electrical properties and show good thermal conductivity, whereby occurring heat losses can be dissipated more quickly. The silver coating prevents oxidation of the copper or copper alloy. Instead of copper or copper alloys are also aluminum or aluminum alloys in question, which have a weight advantage over copper, although the corrosion resistance is not so high. Instead of a silver coating, a coating of tin and other materials or their compounds or layers is possible.
Furthermore, the object according to the invention is achieved by a method for producing a high-current transformer having at least one primary winding and at least one secondary winding with surfaces for contacting, in which first internal surfaces of the at least one secondary winding with an I-beam of electrically conductive material of the high-current transformer with a first soldering material is then connected to a first, higher melting temperature, and then at least one contact plate made of electrically conductive material with outer surfaces of the at least one secondary winding with a second solder · is soldered with a second, compared to the first melting temperature lower melting temperature. It is advantageous hereby that thereby the production, in particular the soldering, can be automated since, due to the different melting temperature in the second soldering process with the lower melting temperature, the compounds already produced in the first soldering process with a higher melting temperature can no longer melt. Thus, the production costs are significantly reduced. It is also achieved that the best possible connection can be used so that the lowest possible transition losses are created. In a measure in which is connected to the at least one contact plate, a board with the first solder with the first, higher melting temperature, is in an advantageous manner ensures that the contact plate can be subsequently exposed at any time further soldering.
After connecting the at least one contact plate to the board, switching elements can be connected to the board and / or the contact plate, in particular with bulges on the contact plate, using the first solder material with the first, higher melting temperature. Here, the positioning and soldering of the switching elements, as well as other electronic components, can be done fully automatically.
According to the measures in which the switching elements, in particular the terminals or housing of the switching elements, are connected to the surfaces of the at least one secondary winding with the second solder material with the second, lower melting temperature, it is achieved that the connection between the contact plate and board no longer can melt. Thus, the entire unit, so the contact plate, the board, the switching elements and other components to be driven by a solder bath for cost-effective and secure production of a soldering.
It is advantageous if a first solder material having a first, higher melting temperature between 220 ° C and 300 ° C, in particular 260 ° C and a second solder with a second, lower melting temperature between 120 ° C and 220 ° C, in particular 180 ° C. , having. This ensures that during the second soldering process with a low melting temperature, the parts fixed during the first soldering process will not be released or the quality of the connections would be impaired.
The invention will be explained in more detail with reference to the accompanying drawings.
Show:
FIG. 1 shows a prior art resistance welding apparatus with a robot and welding tongs attached thereto in a schematic representation; FIG. FIG. 2 is a schematic block diagram of a resistance welding apparatus with a power source for providing the welding current; FIG. 3 shows a resistance welding device, in particular a welding tongs, with an integrated current source for providing the welding current in a schematic representation; 4 is a schematic block diagram of the power source for providing the welding current; 5 shows an embodiment of the current source for providing a direct current; 6 shows the current source according to FIG. 5 in an exploded view; 7 shows the current source according to FIG. 5 with the course of the cooling channels drawn in; Figure 8 is a view of the I-beam of the high current transformer of the power source; FIG. 9 shows the I-beam according to FIG. 8 in a sectional representation; FIG. 10, a contact plate of the high-current transformer of the power source including the board of the synchronous rectifier and the drive circuit; 11, the contact plate of Figure 10 in a sectional view. 12 shows a secondary winding of the high-current transformer with current transformer in exploded view; 13 shows the structure of a secondary winding of the high-current transformer in an exploded view; 14 is a block diagram of a circuit for supplying the synchronous rectifier and the drive circuit with electrical energy; FIG. 15 shows a time characteristic of the supply voltage of the supply circuit according to FIG. 14; FIG. and FIG. 16 shows time courses for illustrating the activation of the switching elements of a synchronous rectifier as a function of the secondary-side currents of the high-current transformer 20
In the illustrated embodiment of Figs. 1 to 16, a construction of a resistance welding apparatus 1 with the essential components will be described. For the same parts, the same reference numerals have been given in the figures.
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In Fig. 1, a resistance welding device 1 for resistance welding of at least two workpieces 2, 3 is shown in perspective with a robot for manipulation. The resistance welding device 1 consists of a welding tongs 4 fastened to the robot with two tong arms 5, on which receptacles 6 for receiving in each case one electrode 7 are arranged. Around the electrodes 7 in each case runs a band 8, which reduces the contact resistance in the resistance welding and protects the electrodes 7. In addition, the image of the produced spot weld produced on the strip 8 can be analyzed and used to assess the quality of the weld. The tape 8 for protecting the electrodes 7 is unrolled by a winding device 9, which may be arranged on the welding gun 4 and the gun arms 5 and along the gun arms 5, the electrode holders 6 and the electrodes 7 back to the winding device 9, where Volume 8 is rolled up again, led. To carry out the spot welding, the welding current, which is supplied by a corresponding power part 19, is conducted through the electrodes 7. As a result, the workpieces 2, 3 are connected to one another by a spot weld produced during the spot welding process. Usually, the power part 19 for providing the welding current is outside the resistance welding device 1, as shown schematically in Fig. 1. The welding current is conducted via corresponding lines 11 to the electrodes 7 and the electrically conductive tong arms 5. Due to the amplitude of the welding current in the range of a few kA, correspondingly large cross sections for the lines 11 are required, which results in correspondingly high ohmic losses.
In addition, long primary leads lead to an increased inductance of the leads 11, which is why the switching frequency with which a high current transformer 12 of a current source 10 is operated is limited, resulting in very large high • • • • ··· Φ + »• * • • ♦ • - • • ♦ • · · • · + ··· • • Φ ····
Current transformers 12. In the prior art, the power unit 19 is located in a control cabinet next to the welding robot, so that very long supply lines, for example up to 30m, are required for the high-current transformer 12 for the welding gun 4 on the robot.
In the solution according to the invention, a considerable reduction in weight and size is achieved, so that positioning of the power unit 19 directly on the robot, in particular in the area of the forceps receptacle, is made possible. In addition, the power unit 19 is preferably made water-cooled.
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FIG. 2 shows a schematic block diagram of a resistance welding device 1 with a current source 10 for providing the welding current. Although the power source 10 is used to provide the welding current for the resistance welding apparatus 1 in the illustrated embodiment, the power source 10, in particular the entire structure of the power supply, can also be used to provide a direct current for other applications. The current source 10 includes a high current transformer 12 having at least one primary winding 13, at least one center-tapped secondary winding 14 and a toroidal core 15. The current transformed by the high current transformer 12 is rectified in a synchronous rectifier 16 and supplied to the gun arms 5 and electrodes 7, respectively, of the resistance welding apparatus 1 , For controlling the synchronous rectifier 16, a drive circuit 17 is provided. The drive circuit 17 sends corresponding control pulses to the switching elements 24 of the synchronous rectifier 16 due to the measured, for example via current transformer 18 secondary-side currents of the high-current transformer 12th
As is well known, due to the high welding currents through the sum of the required line length both significant Ohm'sehe and / or inductive losses as well as forward and switching losses occur in the switching elements 24 of the synchronous rectifier 16. In addition, 17 losses occur in the rectifier, in the supply for the synchronous rectifier 16 and the drive circuit. The corresponding efficiency of such resistance welding devices 1 is correspondingly low.
To generate the primary-side current of the high-current transformer 12, a power unit 19 is provided, which is arranged between a supply network and the current source 10. The power section 19 provides the primary-side current for the high-current transformer 12 and the current source 10 with the desired amplitude and desired frequency.
Fig. 3 shows a resistance welding device 1 with integrated current source 10 in a schematic representation. The current source 10 is directly, in particular as a supporting element, arranged on the welding gun 4 and the gun arms 5 of the resistance welding device 1, so that at least a portion of the lines 11 can be omitted to guide the welding current to the electrodes 7 and thus significantly reduces the line lengths be, since only the connection with a gun arm 5 is required. The current source 10 has at least four contacts 20, 21, 22, 23 in order to form a multipoint contact, wherein two first contacts 20, 21 of one polarity are connected to one tong arm 5 and two further contacts 22, 23 of opposite polarity are connected to the other tong arm 5 are. Advantageously, the two first contacts 20, 21 are arranged with one polarity and the two other contacts 22, 23 with the other polarity in each case opposite, wherein the two further contacts 22, 23 with respect to the two first contacts 20, 21 substantially at 90 ° arranged offset from each other. Due to the Mehrpunktkontaktierung lines that are usually required for connecting the secondary side 14 of the high current transformer 12 with the gun arms 5 and the electrodes 6 of the resistance welding device 1, avoided or their length can be reduced and thus the Ohm'sehen losses as well as contact losses are significantly reduced , Thus, the shortest possible lines with the largest possible cross sections can be used, while maintaining the flexibility of the welding gun 4 remains. Another advantage is that due to such contacting the losses, in particular contact resistance, are reduced. Due to the at least four contacts 20, 21, 22, 23, the welding current to be transmitted can be halved, whereby a Re reduction of the transition losses is caused because the contact resistances are reduced by the wesent Liehe enlargement of the active contact surfaces. For example, each of the four contacts 20, 21, 22, 23 in the dimensioning of a high current transformer 12 and a current source 10 to provide a direct current of 20kA an area between 15cm x 15cm to 25cm x 25cm, preferably 20cm x 20cm, on.
In the illustrated embodiment, the current source 10 is formed substantially cube-shaped, wherein the side surface of the cube, the contacts 20, 21, 22, 23 form. The two first contacts 20, 21 are connected to the one electrode 7 and the other two contacts 22, 23 with the other electrode 7 of the resistance welding device 1 via the gun arms 5. As can be seen from the partially exploded view, at least one gun arm 5, in particular the lower Pliers arm 5, connected via a supporting element 23a of the lower gun arm 5, whereas the other, in particular the upper gun arm 5 is connected via a flexible connection clamp 23b with the other contacts 22, 23. At least one pliers arm 5 is thus directly to the high current transformer 12 and the other pliers arm 5 via a very short line, for example, shorter than 50cm, connected to this. The fact that the lines 11 between the power source 10 and the electrodes 7 and the Zangenar men 5 of the resistance welding device 1 omitted or particularly short fail, the Ohm'sehen and inductive losses can be significantly reduced.
Particular advantages arise when at least two contacts 20, 21 are connected directly or conduction-free and thus contact without contact resistances with a gun arm 5. This can be achieved by virtue of the fact that these two contacts 20, 21 are virtually integrated in the current source 10, which are connected directly to the corresponding parts of the resistance welding device 1, in particular the gun arms 5, ie without laying lines. By directly connecting a gun arm 5 with the contacts 20, 21 of the high current transformer sector 12 thus a leadless connection is achieved, whereas the second gun arm 5 with very short lines with the 24
Contacts 22, 23 must be connected. This allows a very high reduction of the line losses, as the line length is reduced to the minimum. In the prior art, in the optimal case, the high-current transformer is positioned as close as possible to the welding gun 4, so that subsequently the lines from high current transformer 12 to welding gun 4 must be laid, whereas in the inventive solution, the high-current transformer 12 is integrated in the welding gun 4 and at the same time a gun arm 5 is attached directly to the high-current transformer 12, so that only the second gun arm 5 with one or two short lines must be connected. Of course, instead of lines, for example, sliding contacts or other connecting elements can be used. The losses within the power source 10 can be significantly reduced due to the compact design and the direct, so wireless, connection of the components of the power source 10.
Advantageously, all the components of the current source 10, so also the synchronous rectifier 16, the drive circuit 17, the current transformer 18 and all the supply circuits for the synchronous rectifier 16 and the drive circuit 17 are included in the cube or cuboid unit. This means that the integration of the electronic components / circuits creates a unit in the form of a cube on which the user only has to provide energy on the primary side in the form of appropriate alternating voltage or corresponding alternating current, on the secondary side a correspondingly dimensioned direct current or a corresponding to get dimensioned DC voltage with high power. The control and regulation is carried out autonomously in the cube or the current source 10. Thus, the cube or power source 10 is versatile applicable to the supply of high DC components. In particular, the power source 10 is used to supply low voltage and high current, as is common in resistance welding processes.
When used in a resistance welding process, parts of the cube-shaped current source 10 can also be formed by components of the resistance welding device 1, for example parts of the pliers arms 5 or the like, as shown. In this case, the cube or the power source 10 assumes a supporting function by a gun arm 5 is attached directly to the cube. The further tong arm 5 is contacted via connecting lines (not shown). This design can be long supply lines are prevented, so that a significant reduction in losses is achieved. However, so that the cube can be integrated into such a welding tongs 4, it is necessary that its size is kept as low as possible. For example, the cube or the current source 10 has a side length of between 10 cm and 20 cm, in particular 15 cm, when dimensioning the DC current to be delivered of up to 20 kA. Due to this compact design of the cubic current source 10, it is easily possible to integrate them, for example in the main body of the welding gun 4.
4 shows a schematic block diagram of the current source 10 for providing a direct current, in particular a welding current. In this preferred embodiment of the power source 10, ten primary windings 13 of the high current transformer 12 are connected in series and ten secondary windings 14 of the high current transformer 12 are connected in parallel with center tap. By such an embodiment of the high-current transformer 12, the correspondingly high transmission ratio to achieve a correspondingly high secondary-side current even at low numbers of turns of the primary windings 13 and small numbers of turns of the secondary windings 14 can be achieved. For example, with ten primary windings 13 and also ten secondary windings 14, a transmission ratio of 100 can be achieved. The primary current flows through the series-connected primary windings 13 of the high-current transformer 12, whereas the relatively high secondary-side current is divided among the ten secondary windings 14 connected in parallel. The secondary-side partial currents are supplied to the corresponding switching elements 24 of the synchronous rectifier 16. Such a division results in a correspondingly high transmission ratio (here 100} despite low primary and secondary numbers of windings, which in contrast to conventional high-current transformers requires lower numbers of turns on the primary side, whereby the length of the primary winding 13 can be reduced and thus the ohms. As a result of the reduced number of turns of the primary winding 13 and thus a resulting reduction in the line length, the system-typical stray inductance of the high-current transformer 12 is again reduced, as a result of which the high-current transformer 12 can be operated at higher switching frequencies, for example 10 kHz conventional high-current transformers higher switching frequencies in turn cause a reduction in the size and weight of the high-current transformer 12 and thus advantageous installation options For example, the current transformer 12 can be positioned very close to the electrodes 7 of a resistance welding device 1. Thus, the payload of the welding robot due to the low weight of the high current transformer 12 can be reduced, so that with a small cheaper welding robot Auslangen can be found.
Conventional transformers that do not series / parallel the primary and secondary windings would accordingly require more primary windings, resulting in much longer primary wire lengths. Ohmic losses increase on the one hand due to the larger wire length and on the other hand result in a higher stray inductance, for which reason the frequencies with which the transformer can be operated from the prior art are limited to a few kHz.
In contrast, in the design of the high current transformer 12 described herein, the ohmic losses and system leakage inductance of the primary windings 13 and secondary windings 14 are low, therefore frequencies in the range of 10kHz and above can be used. This in turn allows a much smaller size of the high current transformer 12 can be achieved. The smaller size of the high-current transformer 12 or the current source 10 in turn makes it possible to arrange this or these closer to the place where the generated power is needed, for example to the gun arms 5 of a resistance welding device. 1
The parallel connection of the secondary windings 14 of the high-current transformer 12 divides the resulting, high secondary-side current into a plurality of partial currents. These sub-currents are forwarded to switching elements 24 of the synchronous rectifier 16, as shown schematically. To activate the switching elements 24, a drive circuit 17, which is located in the region of the primary winding 13 and secondary winding 14, is provided, wherein both the synchronous rectifier 16, and the drive circuit 17 with associated sensor within the cube, ie within the high-current transformer 12 are arranged , The synchronous rectifier 16 and the drive circuit 17 are designed and dimensioned such that they autonomously, ie without external influence, perform the regulation and control of the current source 10. The cube therefore preferably has no control lines for engagement from the outside, but only connections or contacts for the primary side supply and terminals or contacts for the delivery of the secondary energy generated, in particular the high secondary direct current.
However, it is possible that a corresponding connection of the drive circuit 17 is led out in order to be able to predefine setpoints for the drive circuit 17. By external adjustments, the power source 10 can be optimally adapted to the application. As is known from the prior art, however, systems can be used for changing or transmitting data that work wirelessly, preferably inductively, magnetically or by Bluetooth, so that no control connection has to be led out.
The control and / or regulation of the power source 10 via the integrated sensors. By measuring the secondary-side currents of a secondary winding 14 by means of corresponding current transformers 18, the drive circuit 17 receives the information as to which times the switching elements 24 of the synchronous rectifier 16 are to be switched. Due to the fact that the current transformers 18 measure only a fraction, in this case a tenth, of the secondary-side current of the high-current transformer 12, they can be made smaller, which in turn has a positive effect on the size of the current source 10.
To reduce the forward losses and switching losses, the switching elements 24 of the synchronous rectifier 16 are connected as possible in the zero crossing of the secondary-side currents through the secondary windings 14 of the high-current transformer 12. Since there is some delay from the detection of the zero crossing of the secondary side current through the current transformers 18 to the activation of the switching elements 24 of the synchronous rectifier 16, the drive circuit 17 according to the invention is designed to switch the switching elements 24 of the synchronous rectifier 16 to a preset time before reaching the zero crossing of the current in the secondary winding 14 to switch.
The drive circuit 17 thus causes the switching of the switching elements 24 of the synchronous rectifier 16 at a time at which the currents measured by the current transformer 18 in the secondary winding 14 of the high-current transformer 12 below or exceed a certain turn-on and turn-off threshold. By this measure it can be achieved that the switching elements 24 of the synchronous rectifier 16 are switched substantially during the zero crossing of the currents through the secondary winding 14 of the high current transformer 12, whereby the forward losses and switching losses can be minimized (see also Fig. 16). For a primary winding 13 and secondary winding 14, the supply circuit 48 for supplying the synchronous rectifier 16 and the drive circuit 17 with electrical energy is shown in Fig. 4. This supply circuit 48 is preferably also integrated in the current source 10, ie in the cube. Since the supply of the synchronous rectifier 16 and the Ansteu-connection 17 of the power source 10 must be ensured with sufficient electrical energy at the desired time of delivery of the direct current, such as the welding current, a sufficiently rapid activation of the supply circuit 48 is required (see Fig. 15) or is this designed such that when activating the power source 10 as quickly as possible, a sufficiently high supply voltage is available and then the required power or the required power is supplied.
5 shows the embodiment of the current source 10 according to FIG. 3 in an enlarged view. The power source 10 ready to "« *
Position of a direct current, such as welding current, has substantially the shape of a cube or cuboid, wherein the side surfaces of the cube or cuboid represent the contacts 20, 21, 22, 23, via which the generated direct current to the corresponding consumer, such as the gun arms 5 or electrodes 7 of a resistance welding device 1, can be forwarded. All the components of the current source 10, ie the high-current transformer 12, the synchronous rectifier 16, the drive circuit 17, the current transformer 18, the supply circuit 48, etc. are contained or integrated in this cubic or cuboidal element of the current source 10. This compact design, the losses of the power source 10 can be kept very low and thus their efficiency can be significantly increased because optimal shortening of the lines and thus the switching times with the integration of the electronic components, in particular the boards with the synchronous rectifier 16, the drive circuit 17th and the supply circuit 48 is achieved in the cube. Due to the integration of the synchronous rectifier 16 and the drive circuit 17 and the supply circuits 48 of the power source 10 in the high current transformer 12 and parallel connection of several switching elements 24 of the synchronous rectifier 16 and leadless connection of the switching elements 24 to the secondary windings 14 of the high current transformer 12 are no lines between the synchronous rectifier 16 and Secondary side 14 of the high-current transformer 12 is required, which also eliminates any ohmic losses and further losses due to such lines. The power part 19 for the supply of the high-current transformer 12 is positioned as close as possible to this, in order to achieve the shortest possible connection lines and thus line losses and Leitungsinduktivitäten. Through the integration of all components, a self-sufficient unit is formed, which on the input side only has to be connected to the power part 19 and on the output side - in the case of a resistance welding device 1 - with the gun arms 5 or electrodes 7. Usual lines between the individual circuits of the power source 10 may be omitted or at least significantly reduced in length.
The base of the high-current transformer 12 of the current source 10 forms a transformer element in the form of an I-beam 25 from FIG. 30. Electrically conductive material, in particular copper or a copper alloy, if necessary with a coating, for example of silver. In the recesses 25a of the I-beam 25, the ring cores 15 with the secondary windings 14 of the high-current transformer 12 are arranged on both sides. It is spatially advantageous if the ring cores 15 not circular, but have oval or flat cross-section. In the illustrated embodiment, five ring cores 15 with the respective secondary windings 14 are arranged in parallel in each recess 25a of the I-beam 25. The primary winding 13 or the series-connected primary windings 13 (dot-dash line) extend through the annular cores 15 arranged in the recesses 25a of the I-beam 25 and around the central web of the I-beam 25. By this course of the primary winding 13 through the particular symmetrical In the two recesses 25a of the I-beam 25 arranged ring cores 15, an optimal magnetic coupling to the secondary windings 14 can be achieved. The terminals 26 of the primary winding 13 are led out via at least one opening 27 on an outer surface 28 of the I-beam 25. Via these connections 26, the primary winding 13 of the maximum current transformer 12 can be connected to the corresponding power part 19. The outer surfaces 28 of the I-beam 25 form the two first contacts 20, 21 of the current source 10, which are connected, for example, with the one electrode 7 of the resistance welding device 1. About the recesses 25 a of the I-beam 25 are contact plates 29 whose outer surfaces form the two further contacts 22, 23 of the power source 10 and are insulated from the I-beam 25. The contact plates 29 are likewise made of electrically conductive material, for example copper or a copper alloy, if necessary with a coating, for example of silver. Copper or copper alloys have optimal electrical properties and show good thermal conductivity, whereby occurring heat losses can be dissipated more quickly. The silver coating prevents oxidation of the copper or copper alloy. Instead of copper or copper alloys are also aluminum or aluminum alloys in question, which have a weight advantage over copper, although the corrosion resistance is not so high. Instead of a silver coating, a coating of tin and other materials or their compounds or layers is possible. Between the contact plates 29 and the corresponding terminals of the secondary windings 14 of the high-current transformer 12, the boards 35 of the synchronous rectifier 16 and the drive circuit 17 are arranged. These boards 35 and printed circuit boards are mounted directly to the contact plates 29 and soldered and then attached to the I-beam 25 isolated. By this construction, the secondary-side terminals of the high-current transformer 12 can be directly connected or contacted with the switching elements 24 of the synchronous rectifier 16, without having to lay cables. The outputs of the synchronous rectifier 16 are also preferably connected directly to the contact plates 29, whereby no lines are needed. The contact plates 29 are connected to the I-beam 25, preferably screwed {not shown). On the outer surfaces 28 of the I-beam 25 and the outer surfaces of the contact plates 29 connecting means 30, for example, holes with corresponding threads for receiving screws may be arranged. By means of these connecting devices 30, for example, the lines to the gun arms 5 of a resistance welding device 1, or other devices to be supplied with the DC can be attached or a gun arm 5 can be attached directly to the I-beam 25 or to the contact plates 29.
At the top and the bottom of the cube or cuboid current source 10 cover plates 31 can be arranged and connected to the I-beam 25 and the contact plates 29, for example screwed, be (see Fig. 6). Preferably, the cover plates 31 are also formed of electrically conductive material and bolted to the contact plates 29, whereby a stable unit of the high current transformer 12 results as well as the cover plates 31 and an electrical connection between the contact plates 29 is made. It is thereby achieved that take place via the cover plate 31, a charge balance and thus it can not come to unbalanced loads of the high-current transformer 12. As a result, a separate electrical line, which would electrically connect the two contact plates 29 to one another, is dispensed with in order to produce the voltage or equipotential bonding and to avoid asymmetries. The electrical connection between the two contact plates 29 of the symmetrical arrangement of the high-current transformer 12 or the current source 10 for providing the welding current is thus produced via the cover plates 31. In this case, of course, a corresponding insulation to the I-beam 25 must be ensured. The cover plates 31, like the I-beam 25 and the contact plates 29, are preferably formed from copper or a copper alloy, preferably with a silver coating.
On an outer surface 28 of the I-beam 25, in particular the first contact 20, two inlets 32 for supplying a cooling fluid and an outlet 33 for discharging the cooling fluid are arranged to allow cooling of the components of the power source 10. The cross section of the outlet 33 for discharging the cooling fluid has the sum of the cross sections of all the inlets 32 for the supply of the cooling fluid. For an optimal course of the cooling fluid, the cooling channels 39 are arranged correspondingly (see FIGS. 9 and 11). As the cooling fluid water or other liquid, but also a gaseous coolant can be used.
As can be seen from the exploded view of the current source 10 according to FIG. 6, the current transformers 18 for measuring the secondary-side currents of the high-current transformer 12 are placed directly on the uppermost secondary windings 14, ie, on both sides of the first and uppermost secondary windings 14, respectively the I-beam 25, a current transformer 18 is arranged such that due to the induced current of the current through this secondary winding 14 can be determined. To avoid influencing the currents measured by the current transformer 18 by external magnetic fields, a housing 34 of magnetically conductive material, such as ferrites, for shielding via the current transformers 18 is preferably arranged.
The current transformers 18 are arranged on both sides of the I-beam 25 on the respective first and second secondary windings 14. Due to the current flow through the primary windings 13, the current exits on one side of the I-beam 25, whereby the uppermost
Secondary winding 14 thus forms the first secondary winding 14, whereas on the opposite side of the current now enters the uppermost secondary winding 14 and thus forms the second secondary winding. The use of a full bridge, it is necessary that the current flow is always detected independently of the first and second secondary winding 14, so that depending on the dependence of the current, the corresponding switching elements 24 of the synchronous converter 16 can be controlled. Thus, it is possible that the switching elements 24 of the two sides of the I-beam 25 are driven almost synchronously by a drive signal caused by the current transformer 18.
Between the contact plates 29 and the I-beam 25, the boards 35 of the synchronous rectifier 16 and the drive circuit 17 are arranged. The boards 35 simultaneously form the necessary insulation between the I-beam and the contact plates 29th
The corresponding switching elements 24 of the synchronous rectifier 16 are contacted directly with the secondary windings 14 of the high-current transformer 12. About corresponding bulges 36, in particular crenellated bulges, on the inner surface of the contact plate 29 and corresponding openings 37 on the board 35 below the switching elements 24 can be made a direct contacting of the switching elements 24 with the contact plates 29. The switching elements 24 are preferably formed by suitable field effect transistors whose drain terminals are formed by the housing. The housings of the field-effect transistors are connected directly or conductively to the at least one secondary winding 14 of the high-current transformer 12, so that no lines between these units are required. For example, field effect transistors made of silicon or gallium nitride are used. The current transformers 18 are connected directly to the adjacent board 35 of the synchronous rectifier 16 and the drive circuit 17 and via a suitable line 38 to the opposite board 35 of the synchronous rectifier 16 and the drive circuit 17.
The assembly of the current source 10 according to FIGS. 5 and 6 is preferably carried out by means of a soldering process using two different soldering temperatures. First, the
Secondary windings 14 with the recesses 25a of the I-beam 25 using a solder material, in particular a solder, which melts at a first, higher temperature TSi, for example 260 ° C, connected. The contact plates 29 are also contacted with the circuit boards 35 using a solder material which melts at the first, higher melting temperature TS :, for example 260 ° C. Thereafter, in turn, using a solder material which melts at the first melting temperature Tsa, for example, 260 ° C, the components of the synchronous rectifier 16 and the drive circuit 17 are mounted on the circuit board 35. Due to the capillary action of the circuit board 35 on the contact plate 29, there is no danger of a solution of the circuit board 35 from the contact plate 29. After these operations, the outside contacts of the secondary windings 14 and the contacts on the boards 35 with solder material with a second, compared to the first melting temperature TSi lower melting temperature TS2, for example 180 ° C, sees the contact plates 29 with the boards 35 with the I Carrier 25 is connected, preferably screwed, and then heated above the second melting temperature Ts2 of the solder material, for example 180 ° C, so that the connection of the secondary windings 14 are made with the switching elements 24 of the synchronous rectifier 16. By using a solder material with this second, lower melting temperature Ts2, it is possible to ensure that the solder joints produced using the solder material with a higher melting temperature TSi are not melted or become highly resistant through crystallization processes. Finally, the primary winding 13 is threaded through the toroidal cores 15, and then the current transformers 18 are mounted and contacted and the conduit 38 is laid. By fixing the cover plates 31, the power source 10 is completed. To reduce tensile and bending forces on the components of the power source 10, all the cavities may be potted prior to assembly of the cover plates 31. Via openings provided for this purpose (not shown), for example in the cover plates 31, casting can also take place after the mounting of the cover plates 31.
Fig. 7 shows the current source 10 according to FIGS. 5 and 6 with indicated course of the cooling channels 39 (dashed line drawn).
Accordingly, the cooling channels 39 extend from the two symmetrically arranged inlets 32 first into the contact plates 29, where the strongest heat sources (the switching elements 24 of the synchronous rectifier 16 and the components of the drive circuit 17) and the most sensitive components are cooled with the cool cooling fluid. Thereafter, the cooling channels 39 extend in the outer elements of the I-beam 25 and in the central web of the I-beam 25, where the windings of the high-current transformer 12 are cooled, wherein the two laterally flowing cooling channels 39 collect in the central web to a single cooling channel 39. Thereafter, the cooling channels 39 open in the common outlet 33 for the cooling fluid. The cooling channels in the contact plates 29 and in the I-beam 25 are preferably made by corresponding holes 40 which are completed at the appropriate locations by closing elements 41. Between the I-beam 25 and the contact plates 29, corresponding sealing elements 42, for example O-rings, are arranged to seal the cooling channels 39 (see FIG. 8).
In Fig. 8, the I-beam 25 of the high current transformer 12 is shown isolated from the other components of the high current transformer 12 and the current source 10, respectively. At the mouth of the cooling channels 39, the above-mentioned sealing elements 42, for example in the form of O-rings, arranged. The recesses 25a in the I-beam 25 are formed exactly for receiving the ring core 15, whereby a very compact construction is achieved. At the same time, the central web of the I-beam 25 forms the contact surface for the center tap of the secondary windings 14 of the high-current transformer 12. The center taps of the secondary windings 14 are connected without wires to the central web of the I-beam 25, which in turn corresponding lines can be omitted. Due to the direct connection of the secondary windings 14 to the I-beam 25, a substantial enlargement of the pad is achieved and it can thus again transition losses and line losses can be avoided.
The I-beam 25 forms the base of the high-current transformer 12, around which the secondary windings 14 are arranged such that no connecting lines are required. The outer surfaces of the I-beam 25 provide the two first contacts 20, 21 36 "99 · · · * 9 36" 99 · · · * 9
The current source 10, which are connected directly, ie, without a lead, to the gun arms 5 of the resistance welding device 1. A space-saving arrangement is achieved in that the ring cores 15 are not circular, but oval or flat. Closed ring cores 15 are preferably used. By this design, the series / parallel connection of the primary windings 13 and secondary windings 14 can be realized by the required transmission ratio of the high current transformer 12 is achieved for the high direct current to be supplied DC at reduced numbers of turns of the primary windings 13 and secondary windings 14. Such a construction pays off in particular if at least three secondary windings 14 connected in parallel are arranged on each side of the I-beam 25.
9 shows the sectional view through the I-beam 25 from FIG. 8 along the section line IX-IX. From this, the course of the cooling channels 39 to the common outlet 33 for the cooling fluid can be clearly seen.
10 shows a contact plate 29 of the high-current transformer 12 or the current source 10 as well as the board 35 arranged thereon for the synchronous rectifier 16 and the drive circuit 17 in an enlarged representation. As already mentioned above, the switching elements 24 of the synchronous rectifier 16 are contacted on the one side directly with the corresponding secondary windings 14 of the high-current transformer 12 and connected directly to the contact plate 29 on the other side. For this purpose, on the inner surface of the contact plate 29 bulges 36, in particular crenellated bulges arranged, which protrude into corresponding openings 37 on the board 35 and there contact the source terminals of the openings 37 arranged over the switching elements 24 directly or without wires , By the bulges 36 can be dispensed with connecting lines between the switching elements 24 of the synchronous rectifier 16 and the contact plates 29, whereby on the one hand, the ohmic losses can be reduced and on the other hand, the thermal transition between the switching elements 24 and the contact plates 29 can be improved. Finally, the production cost is reduced, since no connecting lines must be laid and connected, but the switching elements 24 are connected directly to the bulges 36, preferably soldered. Also so that a simple positioning of the board 35 allows and thus the production can be substantially simplified.
Due to the arrangement of the drive circuit 17 and the synchronous rectifier 16 on the board 35, which is arranged on the inside of the contact plate 29, the direct or non-conducting contact of the terminals of the secondary windings 14 with the switching elements 24 of the synchronous rectifier 16 and also a direct or leadless contact the outputs of the synchronous rectifier 16 can be achieved with the contact plate 29. Preferably, the high-current transformer 12 or the current source 10 to provide the DC current is symmetrical, on both sides of the symmetrically arranged secondary windings 14 each have a circuit board 35 is arranged with a part of the synchronous rectifier 16 and the drive circuit 17 below each contact plate 29.
In the synchronous rectifier 16 according to FIG. 10, ten switching elements 24 are arranged in a row. To ensure that all parallel switching elements 24 are driven substantially simultaneously and run time losses have little effect, there is a symmetrical control of the switching elements 25 from both sides, ie, on both sides arranged gate driver are each preferably five switching elements 24 from the right and left driven. It is also possible to arrange other drive variants, such as an additionally centrally running gate driver, whereby the line lengths and their inductances are divided into three. By such a parallel control of the gates of the switching elements 24 of the synchronous rectifier 16 short Ansteuerwege and thus almost synchronous switching times of the switching elements 24 are ensured, since no or hardly run-time losses occur.
When mounting the board 35 on the contact plate 29, the bulges 36 of the contact plate 29 project through the openings 37 in the board 35 through which simultaneously the back of the board 35 with the contact plate 29 can be securely connected or soldered and additionally on the opposite Side arranged switching elements 24 also connected to the contact plate 29 and can be soldered. This eliminates the usual high wiring costs. Also, a slight positioning of the board 35 on the contact plate 29 is thus possible and can no longer slip during soldering.
If the synchronous rectifier 16, the drive circuit 17 and the supply circuit 48 are arranged on the circuit board 35, an autonomous structure can be achieved in the integration of the circuit board 35 in the high-current transformer 12. It is furthermore advantageous if the drive circuit 17 is arranged on both sides of the switching elements 24 arranged in parallel and in series, since this achieves a shortening of the conduction paths to the individual switching elements 24. Thus, it can be ensured that all parallel switching elements 24 are turned on within a very short period of time.
Due to the two-sided arrangement of the drive circuit 17, a halving of the line length and, concomitantly, a reduction of the line inductances and thus a significant shortening of the switching times 24 are achieved. On one side of the board 35, a solderable surface for soldering to the contact plate 29 is preferably provided over the entire surface, whereby a secure connection with the contact plate 29 can be achieved. Thus, the contact resistance can be significantly reduced, since a full-surface connection of the board 35 has a lower contact resistance. Instead of the preferred direct connection by soldering and short connecting wires, so-called bonding wires, can be provided.
The supply circuit 48 is preferably designed to form correspondingly high switching currents, for example between 800A and 1500A, in particular 1000A, and for supplying the components with a corresponding supply voltage. Due to the very high switching current, a very short switching time, in particular in the ns range, can be achieved. This ensures that the switching elements 24 are always switched to zero crossing or immediately before the zero crossing with low output current, so that no or hardly any switching losses occur. If a data communication circuit is provided for the wireless transmission of data, preferably inductive, magnetically or via Bluetooth, data can be transmitted wirelessly from and to the board 35 (not shown). Thus, an adjustment of the switching times can be made to different applications of the high current transformer 12. Likewise, from a memory 35 (not shown) arranged on the circuit board 35, data for further processing or checking or for quality monitoring can be read out.
O o
To provide protection of the switching elements 24 of the synchronous rectifier 16 from overvoltages, it is advantageous to turn on the switching elements 24 when they are not needed. In the case of application in a resistance welding device 1, the active synchronous rectifier 16 is thus activated in the welding pauses in order to avoid destruction of the switching elements 24. It is monitored whether a primary current or secondary current flows through the high-current transformer 12, and in the case of no current flow, while the welding gun 4 is positioned according to a new welding point, the drive circuit 17 activates all switching elements 24 by appropriate control of the gates. If, after positioning the welding gun 4, the current source 10 is activated, ie a manual or automatic welding operation is started, then an alternating voltage is applied to the primary winding 13 of the high-current transformer 12, which in turn is detected by the drive circuit 17 due to a current flow, and thus the protection mode of the switching elements 24 is deactivated. Of course, the activation and deactivation of the switching elements 24 of the synchronous rectifier 16 also via control signals that are sent by radio or inductively or magnetically to the drive circuit 17, take place. At the switched-on switching elements 24 any overvoltages can cause no damage. Also, a certain minimum protection of the switching elements 24 by means of Zener diodes can be provided.
FIG. 11 shows a sectional view through the contact plate 29 according to FIG. 10 along the section line XI-XI. From this, the course of the cooling channels 39 can be clearly seen. The production-related openings in the bores 40 for forming the cooling channels 39 are sealed by corresponding closing elements 41. The 40 ·· # »# • · · Μ0 ·
End elements 41 can be realized by corresponding screws which are screwed into corresponding threads in the bores 40.
O
12 shows a toroidal core 15 with two secondary windings 14 of the high-current transformer 12 arranged thereon, together with a current transformer 18 arranged above it, which has been shown in an exploded view. The current transformer 18 is protected by the shielding housing 34 and a shield 43 from foreign magnetic fields, so that the secondary side current through the secondary winding 14 can be measured as accurately as possible and the drive circuit 17 for controlling the switching elements 24 of the synchronous rectifier 16 can be supplied. To shield magnetic fields, ferrites are particularly suitable as materials. The current transformer 18 is thereby positioned or fastened over a partial region of one of the two arranged secondary windings 14. As known from the prior art, the current transformer 18 is formed of a magnetic core with a winding disposed above, wherein the terminals of the winding are connected to the drive circuit 17. Furthermore, the shield 43 and a core plate for the current transformer 18 is disposed between the ring core 15 and the secondary winding 14, wherein the core of the current transformer 18 is placed on this core sheet.
O
In this construction of the high-current transformer 12, two secondary windings 14 constructed in this way are arranged on both sides of the I-beam 25, so that the drive circuit 17 measures the current flow through one of the secondary windings 14 connected and positioned in parallel on both sides. If the drive circuit 17 is connected to these current transformers 18, an exact control or regulation becomes possible because the states in the high-current transformer 12 can be detected via the current transformers 18.
Due to the above-described parallel connection of the secondary windings 14, the same current flows in each secondary winding 14. Thus, the current of only one secondary winding 14 has to be grasped in order to be able to infer the total current flow. In a parallel circuit of ten secondary windings 14 only one tenth of the total current flow is measured by the current transformers 18, which is why they can be dimensioned much smaller. This in turn achieves a reduction in the size of the high-current transformer 12 or the current source 10. It is advantageous if the current transformers 18 are arranged oriented substantially at 90 ° to the direction of the direct current, in particular welding current, since interference by the magnetic field caused by the direct current and thus measuring errors can thereby be reduced. Thus, a very accurate measurement can be performed.
13, the secondary windings 14 of the high-current transformer 12 are preferably provided by two sheets 44, 45 which are insulated from one another by an insulating layer 46, for example a paper layer, with an essentially S-shaped course around the cross section of a toroidal core 15 and formed by the ring core 15, which are arranged in each other. To a ring core 15 so two secondary windings 14 and the parts of the secondary winding 14 are arranged with center tap. The outer surfaces 47 of the sheets 44, 45 of the secondary windings 14 simultaneously form the contact surfaces for contacting with the switching elements 24 of the synchronous rectifier 16 and the I-beam 25, which acts as the center of the rectification. Thus, no lines for connecting the secondary windings 14 of the high-current transformer 12 with the switching elements 24 of the synchronous rectifier 16 are required. The secondary windings 14, in particular the laminations 44, 45 forming the secondary windings 14, are connected directly or conductively to the switching elements 24 of the synchronous rectifier 16 and to the middle web of the I-beam 25 or the center of the rectification. This results in a very space-saving and compact design with low weight and low losses. At the same time for the connection of the secondary winding 14 with the central web of the I-beam 25 and the switching elements 24 of the synchronous rectifier 16 are relatively large areas 47 for contacting available to ensure the highest current flow with as little loss. By this arrangement, a center rectifier is realized on the secondary side, wherein the I-beam 25 with the connected one end of the secondary windings 14 form the center. 42
The ring core 15 may be formed of ferrites, amorphous materials or nanocrystalline materials. The better the materials used with regard to the magnetic properties, the smaller the toroidal core 15 can be made. Of course, this also increases the price of the ring core 15. It is essential in the formation of the sheets 44, 45 that they are folded or bent so that they are at least once passed through the ring core 15. The two arranged on a ring core 15 sheets 44, 45 and secondary windings 14 are formed gegengleich and isolated from each other.
O
O
14 shows a block diagram of a supply circuit 48, in particular of a power supply, for supplying the synchronous rectifier 16 and the drive circuit 17 with electrical energy. The supply circuit 48 is connected to the secondary side or terminals of the secondary winding 14 of the high-current transformer 12 and includes a peak rectifier 49, a voltage booster 50, a series regulator 51 and a voltage divider 52. The voltage booster 50 or booster ensures that the supply of the components the power source 10 is available as quickly as possible. At the same time, the internal supply voltage of the active synchronous rectifier 16 is generated as quickly as possible. By using the voltage booster 50, it is ensured in the initial phase of the activation that the required amplitude of the supply voltage is generated first as early as possible in order to ensure a reliable function of the synchronous rectifier 16 integrated into the high-current transformer 12 at the earliest possible point in time.
FIG. 15 shows the timing of the supply voltage V of the supply circuit 48 shown in FIG. 14. The ramp of the voltage rise AV / At is made sufficiently steep so as to ensure that the required voltage VCC with a maximum time delay Td at the synchronous rectifier 16 and the drive circuit 17 is present. For example, the time delay Td < 200ps. By appropriate design of the circuits of the peak rectifier 49 and voltage booster 50 and correspondingly low capacitances, a sufficient rate of rise of the voltage can be achieved. It can therefore be said that first the minimum height of the supply voltage is ensured with a steep rise and only then the correct supply is built up.
16 shows timing charts of the secondary-side current Is of the high-current transformer 12 and the control signals Gi and G2 for the switching elements 24 of the synchronous rectifier 16 for illustrating the lossless driving. By measuring the secondary-side currents Is of a secondary winding 14 by means of corresponding current transformers 18, the drive circuit 17 receives the information as to when the switching elements 24 of the synchronous rectifier 16 are to be switched. To reduce the forward losses and switching losses, the switching elements 24 of the synchronous rectifier 16 are connected as possible in the zero crossing of the secondary-side currents through the secondary windings 14 of the high-current transformer 12. Since it comes from the detection of the zero crossing of the secondary side current 1 $ through the current transformer 18 to the activation of the switching elements 24 of the synchronous rectifier 16 to certain delays tPre, the drive circuit 17 is inventively designed to the switching elements 24 of the synchronous rectifier 16 at a preset time before to drive to reach the zero crossing of the current in the secondary winding 14. The drive circuit 17 thus causes the switching of the switching elements 24 of the synchronous rectifier 16 at times at which measured by the current transformer 18 currents Is in the secondary winding 14 of the high current transformer 12 below a certain switch-on threshold ISe and switch-off threshold ISA or exceed. By this measure it can be achieved that the switching elements 24 of the synchronous rectifier 16 are switched substantially through the secondary winding 14 of the high-current transformer 12 during the zero crossing of the currents Is, whereby the forward losses and switching losses of the switching elements 24 of the synchronous rectifier 16 can be minimized. The switch-on and switch-off of the switching elements 24 of the synchronous rectifier 16 is thus not with the zero crossing of the secondary-side current but with reaching the defined 44th
Switch-on threshold ISE and switch-off threshold Ia determined. The switch-on threshold ISe and switch-off threshold ISa are defined according to the expected switching delays. If necessary, the switch-on threshold ISE and switch-off threshold I3A can be made adjustable in order to be able to reduce the losses even more. In a 20kA high current transformer 12, for example, the switching timing 100ns may be set before the zero crossing, so that the switching elements 24 of the synchronous rectifier 16 must be switched within this period.
O
A typical prior art high current transformer for a resistance welding device for providing a welding current of, for example, 20kA has approximately 40-50kW losses. Overall, to provide a prior art welding current of 20kA, a connected load of up to 150kW is required, with total losses of about 135kW, resulting in an efficiency of about 10%. In contrast, a high current transformer 12 of the subject type shows only about 5-6kW losses. The line losses can be reduced from the usual 30kW to 20kW. Thus, in an inventive o
Resistance welding device 1 for the generation of a welding current of 20kA, the connection power can be reduced to 75kW, since the total losses are only about 60kW. The resulting efficiency is thus about twice as high at about 20% as in the prior art. This comparison shows very clearly the possible savings potential, in particular in production lines in the automotive industry with a large number of resistance welding devices.
Basically, the described current source 10 or the high-current transformer 12 in the form of a cube or cuboid, wherein two side surfaces are formed by an I-beam 25, on which side surfaces electrically insulated contact plates 29 are arranged to form the third and fourth side surface. At the front side, in each case a cover plate 31, which is electrically insulated from the I-beam 25, is arranged to form the fifth and sixth side faces of the cube or cuboid. Within the cube, in particular the side surfaces, the synchronous rectifier 16 and the drive circuit 17 are arranged on at least one circuit board 35 or printed circuit board. The cube thus has only terminals 26 for the primary windings 13 of the high-current transformer 12 and the side surfaces as contact surfaces for the decrease of the direct current or the DC voltage. In addition, still cooling connections, in particular the inlets 32 and the outlet 33 are provided for a cooling fluid. Control lines for the integrated in the cube synchronous rectifier 16 and the drive circuit 17 are preferably not provided, since this system operates independently and thus no connections to the power unit 19 and to a control device of the system are necessary. In such a structure, preferably no control lines are needed, but the power source 10 only connected on the primary side with a power unit 19, whereupon the correspondingly dimensioned direct current of, for example, 15kA to 40kA is available on the secondary side. The user does not need to make any settings, but only connect the power source 10. The combination of the actual independent stand-alone components to such a common unit causes the size and thus the weight of the power source 10 can be substantially reduced. At the same time, the unit can also be used as a load-bearing element directly in an application, in particular a welding tongs 4. Also, the user-friendliness is significantly increased.
It is also essential in the construction according to the invention that the switching elements 24 be connected to the corresponding components without wires, i. the source of the welding current flowing source of the switching elements 24 formed by field effect transistors are directly connected or soldered to the bulges 36 of the contact plate 29, wherein the gate terminals of the switching elements 24 directly on the board 35 and the drive circuit 17 (gate Driver) are arranged or soldered. Thus, the inductances of lines can be reduced by completely saving the lines, so that high switching speeds and very low forward losses can be achieved. 46
In the illustrated and described embodiment, the high current transformer 12 has been dimensioned for a current of 20kA at an output voltage between 5V and 10V. In this case, the I-beam 25 has a height of 15 cm, so that on both sides in each case five secondary windings 14 can be arranged with the ring cores 15. In order to come to a corresponding transmission ratio of 100, ten primary windings 13 are necessary in the illustrated embodiment.
O
O
If one now wants to dimension the high-current transformer 12 for a higher current of, for example, 30 kA, the number of secondary windings 14 used can simply be increased. For example, on both sides in the recesses 25a of the I-beam 25 each have seven secondary windings 14 are arranged, wherein the I-beam 25 is increased in height accordingly, for example, is performed only 5cm higher or a correspondingly larger body is used. Thus, the I-beam 25 of the high-current transformer 12 is supplemented on both sides only by two secondary windings 14 in order to provide a higher current can. The enlargement also increases the contact cooling surfaces. Furthermore, correspondingly more switching elements 24 are arranged in parallel. The primary winding 13 can be reduced to a smaller number of turns, for example seven windings, so that a ratio of 98, for example, is achieved. Higher primary winding losses are compensated by the higher primary current due to the possible increase of the cross-section and the reduction of the line length.
An increase of the secondary welding current from 20kA to 30kA thus only results in an extension of the cube or high-current transformer 12 by 5 cm, for example.
Since the high-current transformer 12 preferably operates autonomously and has no control lines, should be possible for any error messages communication to the outside with external components, in particular a control device. For this purpose, the secondary circuit consisting of the secondary windings 14 and the synchronous rectifier 16 and the drive circuit 17 can be used. In this case, in certain states, in particular when the high-current transformer 12 is idle, it can be deliberately short-circuited with the aid of the synchronous rectifier 16, so that an open-circuit current flow in the primary lines is detected by an external monitoring unit or a control device and thus a communication or an error message due to the current can take place.
For example, by integrating a temperature sensor in the high-current transformer 12, in particular at the synchronous rectifier 16, the temperature can be detected and evaluated. If, for example, the temperature rises above a defined threshold value, then the synchronous rectifier 16 is short-circuited in an idle manner, ie in the welding pauses, by the drive circuit 17. Since the external control device knows the idling state while no welding is being performed, it is detected by the increased current flow in the primary lines of the high-current transformer 12. Now it can be checked by the external control device, whether the cooling circuit is activated, or this has an error or the cooling capacity is increased, so that a better cooling takes place.
Of course, different error messages can be communicated to the outside via corresponding switching or pulse patterns, ie defined opening and closing of the switching elements 24 of the synchronous rectifier 16 when idling. For example, different temperature values, secondary voltages, currents, error messages, etc. can be sent to the outside.
But it is also possible that such communication is performed during a weld, although such detection is much more difficult. In this case, for example, corresponding signals aufzumodulieren the primary-side current, in particular by the primary windings 13.

权利要求:
Claims (50)
[1]
claims; 1. High current transformer (12), in particular for a current source (10) for providing a welding current of a resistance welding device (1), with at least one primary winding (13) and at least one secondary winding (14) with center tap, characterized in that at least to form a Mehrpunktkontaktierung four contacts (20, 21, 22, 23) are provided, which contacts (20, 21, 22, 23) are formed by four contact surfaces, within which the at least one primary winding (13) and the at least one secondary winding (14) in one Series / parallel circuit are arranged.
[2]
2. High-current transformer (12) according to claim 1, characterized in that a plurality, preferably at least 10, connected in series primary windings (13) and a plurality, preferably at least 10, parallel-connected secondary windings (14) are provided with center tap.
[3]
3. High-current transformer (12) according to claim 1 or 2, characterized in that the transmission ratio is at least 10 to 1000, preferably at least 100.
[4]
4. High-current transformer (12) according to any one of claims 1 to 3, characterized in that an I-beam (25) is provided made of electrically conductive material, in the recesses (25 a) in each case at least one ring core (15) is arranged, in each case a terminal of each secondary winding (14) is directly contacted with an inner surface and the contact plate (29) of the I-beam (25), and that the outer surfaces (28) of the I-beam (25) form two contacts (20, 21).
[5]
5. High-current transformer (12) according to claim 4, characterized in that the center tap of the at least one secondary winding (14) of the high-current transformer (12) is conductively connected to the I-beam (25).
[6]
6. High current transformer (12) according to claim 4 or 5, characterized in that the at least one primary winding (13) through the at least one ring core (15) and around the central web of the I-beam (25) is arranged to extend.
[7]
7. High-current transformer (12) according to any one of claims 4 to 6, characterized in that above the recesses (25 a) of the I-beam (25) and the secondary winding (14) arranged therein each case a contact plate (29) made of electrically conductive Materi al which is connected via a synchronous rectifier (16) and a drive circuit (17) to the respective other terminals of each secondary winding (14), wherein the outer surfaces of the contact plates (29) the two further contacts (22, 23) of the power source (10 ) form.
[8]
8. High-current transformer (12) according to one of claims 4 to 7, characterized in that the connections (26) of the at least one primary winding (13) via at least one opening (27) led out on an outer surface (28) of the I-beam (25) are.
[9]
9. High-current transformer (12) according to one of claims 1 to 8, characterized in that in each case a secondary winding (14) with center tap by two mutually insulated sheets (44 45) of electrically conductive material having a substantially S-shaped, opposite course around the cross section a ring core (15) and through the ring core (15) is formed, wherein the outer surfaces (47) of the sheets (44, 45} form contacts
[10]
10. High-current transformer (12) according to claim 9, characterized marked characterized in that the sheets (44, 45) for forming the Sekundärwick development (14) by an insulating layer (46) are isolated from each other.
[11]
11. High current transformer (12) according to any one of claims 4 to 10, characterized in that the I-beam (25) and the contact plates (29) form a cube or cuboid unit wherein between the I-beam (25) and the contact plates (29) an electrical insulation is arranged.
[12]
12. High current transformer (12) according to claim 11, characterized in that on the end sides of the I-beam (25) cover plates (31) are arranged.
[13]
13. High-current transformer (12) according to claim 12, characterized in that the cover plates (31) formed from electrically conductive material and with the contact plates (29) are screwed, so that the contact plates (29) are electrically connected.
[14]
14. High-current transformer (12) according to claim 12 or 13, characterized in that the cover plate (31) relative to the I-beam (25) is electrically insulated.
[15]
15. High-current transformer (12) according to any one of claims 4 to 14, characterized in that the I-beam (25) and / or the contact plates (29) and / or the cover plates (31) and / or the sheets (44, 45 ) is formed to form the secondary winding (14) of copper or a copper alloy, preferably with a silver coating.
[16]
16. High-current transformer (12) according to any one of claims 4 to 15, characterized in that on the outer surfaces (28) of the I-beam (25) and the outer surfaces of the contact plates (29) connecting means (30), preferably bores with a thread for Recording of screws, are arranged.
[17]
17. High-current transformer (12) according to one of claims 1 to 16, characterized in that on the first secondary winding (14) each side of the I-beam (25) each have a current transformer (18) for measuring the current through this secondary winding (14). is arranged.
[18]
18. High-current transformer (12) according to claim 17, characterized in that each current transformer (18) by a housing (34) and preferably a shield (43) is shielded from magnetically conductive material.
[19]
19. High current transformer (12) according to any one of claims 4 to 18, characterized in that in the I-beam (25) and the contact plates (29) channels (39) are arranged to guide a cooling fluid.
[20]
20. High current transformer (12) according to claim 19, character- ized in that on an outer surface of the I-beam (25) two inlets (32) for supplying the cooling fluid and an outlet (33} for discharging the cooling fluid are arranged, wherein the Cooling channels (39) from each inlet (32) to the contact plates (29) and over the I-beam (25) to the outlet (33) extending are arranged.
[21]
21. High current transformer (12) according to any one of claims 1 to 20, characterized in that the at least one secondary winding (14) has a synchronous rectifier (16) with switching elements (24) and a circuit (17) for controlling the switching elements (24) of Synchronous rectifier (16) is connected.
[22]
22. High-current transformer (12) according to claim 21, characterized in that the drive circuit (17) for activating the switching elements (24) of the synchronous rectifier (16) is formed at a preset time before reaching the zero crossing of the current in the secondary winding (14) ,
[23]
23. High-current transformer (12) according to claim 20 or 21, characterized in that the switching elements (24) of the synchronous rectifier (16) are connected without wires to the at least one secondary winding (14).
[24]
24. High-current transformer (12) according to claim 22 or 23, characterized in that the drive circuit (17) and the synchronous rectifier (16) are arranged on at least one circuit board (35), which circuit board (35) on the inner surface of at least one contact plate (29 ) is arranged.
[25]
25. High current transformer (12) according to claim 24, characterized in that each board (35) of the synchronous rectifier (16) and the drive circuit (17) has openings (37) over which the switching elements (24) are arranged, and that the inner surface the contact plates (29) at the locations of the openings (37) in the board (35) of the synchronous rectifier (16) bulges (36), in particular crenellated recesses, so that the switching elements (24) through the openings (37) of the Circuit board (35) projecting bulges (36) on the inner surface of the contact plates (29) are leitungslos kontaktier-bar are 52 ·. ♦ ♦ ♦ ♦ ♦.
[26]
26. High-current transformer (12) according to claim 25, characterized in that the source terminals of the switching elements formed by field effect transistors (24) via the bulges (36), in particular crenellated bulges, directly and electrically connected to the contact plate (29). O
[27]
27. High current transformer (12) according to claim 25 or 26, characterized in that each board (35) for forming the electrical insulation between the I-beam (25) and the contact plates (29) is arranged.
[28]
28. Transformer element for a high current transformer (12) having at least one primary winding (13) and at least one secondary winding (14) with center tap, characterized by an I-shaped carrier (25) made of electrically conductive material whose recesses (25 a) for receiving in each case at least a ring core (15) is arranged with a secondary winding (14) arranged thereon, and its opposite inner surface (s) is designed for the direct contacting of in each case one terminal of each secondary winding (14). O
[29]
29. Transformer element according to claim 28, characterized in that on an outer surface (28) of the I-beam (25) at least one opening (27) for guiding the connections (26) of the at least one primary winding (13) is provided.
[30]
30. Transformer element according to claim 28 or 29, characterized in that the I-beam (25) made of copper or a copper alloy, preferably formed with a silver coating.
[31]
31. Transformer element according to one of claims 28 to 30, characterized in that on the outer surfaces (28) of the I-beam (25) connecting means (30), preferably bores are arranged with a thread for receiving screws.
[32]
32. Transformer element according to one of claims 28 to 31, characterized in that in the I-beam (25) channels (39) are arranged to guide a cooling fluid.
[33]
33. Transformer element according to claim 32, characterized in that on an outer surface (28) of the I-beam (25) two inlets (32) for supplying the cooling fluid and an outlet (33) for discharging the cooling fluid are arranged.
[34]
34. contact plate (29) for a high current transformer (12) having at least one primary winding (13) and at least one secondary winding (14) with center tap, characterized in that on one side bulges (36), in particular crenellated bulges, for receiving a board ( 35) and for direct contact with switching elements (24) are provided.
[35]
35. contact plate (29) according to claim 34, characterized in that on the at least one circuit board (35) a synchronous rectifier (16) and a drive circuit (17) and optionally a supply circuit (48) for autonomous operation of the high-current transformer (12) is arranged ,
[36]
36. contact plate (29) according to claim 34 or 35, characterized in that the bulges (36) for the non-contacting of the switching elements (24) of the synchronous rectifier (16) are formed by the bulges (36) in accordance with on the board ( 35) provided openings (37) are arranged so that over the openings (37) arranged switching elements (24) of the synchronous rectifier (16) are contacted.
[37]
37. Contact plate (29) according to any one of claims 34 to 36, characterized in that the switching elements (24) are soldered directly to the bulges (36).
[38]
38. Contact plate (29) according to claim 36 or 37, characterized in that the contact plate (29) made of copper or a copper alloy, preferably with a silver coating, is formed. 54 * * * * · · * * * * * * * • · ♦ «·« | | ·· ··· · ** t * · «« ····
[39]
39. contact plate (29) according to one of claims 36 to 38, characterized in that on the outer surfaces of connecting means (30), preferably bores are arranged with a thread for receiving screws.
[40]
40. contact plate (29) according to one of claims 36 to 39, characterized in that a plurality of bulges (36) are arranged side by side, so that a plurality of switching elements (24) are contacted in parallel accordingly.
[41]
41. Contact plate (29) according to claim 40, characterized in that in a row a plurality, in particular ten, bulges (36) for correspondingly parallel switching elements (24) and a plurality, in particular ten, rows of protrusions (36) are arranged one above the other.
[42]
42. Secondary winding (14) for a high current transformer (12), in particular for a current source (10) for providing the welding current for a resistance welding device (1), characterized in that a sheet (44, 45) of electrically conductive material with substantially S At least partially around the cross section of a ring core (15) and through the ring core (15) is arranged, wherein the outer surfaces (47) of the sheets (44, 45) form contacts or connections.
[43]
43. secondary winding (14) according to claim 42, characterized in that the annular core (15), a further sheet (44, 45) for forming a further secondary winding (14) is arranged, whereby two mutually insulated sheets (44, 45) of electrically conductive material having a substantially S-shaped, congruent course at least partially around the cross section of the toroidal core (15) and through the toroidal core (15) are provided, wherein the outer surfaces (47) of the sheets (44, 45) form contacts.
[44]
44. secondary winding (14) according to claim 42 or 43, characterized in that the sheets (44, 45) are insulated from each other by an insulating layer (46). 55
[45]
45. secondary winding {14) according to any one of claims 42 to 44, characterized in that the sheets (45, 46) made of copper or a copper alloy, preferably with a silver coating, are formed.
[46]
46. A method for producing a high-current transformer (12) having at least one primary winding (13) and at least one secondary winding (14) with surfaces (47) for contacting, characterized in that first internal surfaces (47) of the at least one secondary winding (14) an I-beam (25) of electrically conductive material of the high-current transformer (12) is connected to a first solder material having a first, higher melting temperature (TSi), and then at least one contact plate (29) of electrically conductive material having outer surfaces (47) the at least one secondary winding (14) is connected to a second soldering material having a second melting temperature (Ts2) which is lower than the first melting temperature (TSi).
[47]
47. The method according to claim 46, characterized in that a circuit board (35) is connected to the at least one contact plate (29) with the first solder material having the first, higher melting temperature (TSi).
[48]
48. The method according to claim 47, characterized in that after connecting the at least one contact plate (29) to the circuit board (35) switching elements (24) with the circuit board (35) and / or the contact plate (29), in particular with bulges ( 36) on the contact plate (29), using the first solder material with the first, higher melting temperature (T31) are connected.
[49]
49. Method according to claim 48, characterized in that the switching elements (24), in particular the connections or housings of the switching elements (24), with the surfaces (47) of the at least one secondary winding (14) with the second soldering material with the second, lower melting temperature (Ts2) are connected.
[50]
50. The method according to any one of claims 46 to 49, characterized in that a first brazing material with a first 56th

Melting temperature between 220 ° C and 300 ° C, in particular 260 ° C, and a second solder material having a second melting temperature between 120 ° C and 220 ° C, in particular 180 ° C, is used.

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同族专利:

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公开号 | 公开日

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KR20140092867A|2014-07-24|

---

JP6002295B2|2016-10-05|

---

WO2013063626A2|2013-05-10|

---

JP5918379B2|2016-05-18|

---

ES2627867T3|2017-07-31|

---

CN105345244A|2016-02-24|

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JP2016005847A|2016-01-14|

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KR101626812B1|2016-06-02|

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EP2773481B1|2017-03-15|

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CN105345244B|2017-07-04|

---

EP2773481A2|2014-09-10|

---

PL2773481T3|2017-08-31|

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CN104010758B|2016-10-26|

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PL2913136T3|2016-12-30|

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AT512064B1|2015-11-15|

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EP2913136A1|2015-09-02|

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JP2015501539A|2015-01-15|

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KR20160007688A|2016-01-20|

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US10141106B2|2018-11-27|

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CN104010758A|2014-08-27|

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KR101819631B1|2018-02-28|

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EP2913136B1|2016-06-22|

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US10325720B2|2019-06-18|

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ES2592680T3|2016-12-01|

---

US20160322158A1|2016-11-03|

---

US20140313679A1|2014-10-23|

---

WO2013063626A3|2013-07-18|

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法律状态:

优先权:

---

申请号 | 申请日 | 专利标题

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ATA1601/2011A|AT512064B1|2011-10-31|2011-10-31|HIGH-FLOW TRANSFORMER, TRANSFORMER ELEMENT, CONTACT PLATE AND SECONDARY WINDING, AND METHOD FOR PRODUCING SUCH A HIGH-SPEED TRANSFORMER|ATA1601/2011A| AT512064B1|2011-10-31|2011-10-31|HIGH-FLOW TRANSFORMER, TRANSFORMER ELEMENT, CONTACT PLATE AND SECONDARY WINDING, AND METHOD FOR PRODUCING SUCH A HIGH-SPEED TRANSFORMER|

---

EP12784411.6A| EP2773481B1|2011-10-31|2012-10-31|Heavy-current transformer having at least four contacting points|

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KR1020147014743A| KR101626812B1|2011-10-31|2012-10-31|Heavy-current transformer having a multi-point contacting, transformer element, contact plate and secondary winding, and method for producing such a heavy-current transformer|

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PL12784411T| PL2773481T3|2011-10-31|2012-10-31|Heavy-current transformer having at least four contacting points|

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CN201510854681.2A| CN105345244B|2011-10-31|2012-10-31|Method for manufacturing strong current transformer|

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JP2014537421A| JP5918379B2|2011-10-31|2012-10-31|High current transformer, transformer element, contact plate, and secondary winding, and method of manufacturing such a high current transformer|

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US14/354,982| US10141106B2|2011-10-31|2012-10-31|Heavy-current transformer having a multi-point contacting, transformer element, contact plate and secondary winding, and method for producing such a heavy-current transformer|

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KR1020167000167A| KR101819631B1|2011-10-31|2012-10-31|Heavy-current transformer having a multi-point contacting, transformer element, contact plate and secondary winding, and method for producing such a heavy-current transformer|

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PCT/AT2012/000273| WO2013063626A2|2011-10-31|2012-10-31|Heavy-current transformer, transformer element, contact plate and secondary winding, and method for producing such a heavy-current transformer|

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ES12784411.6T| ES2627867T3|2011-10-31|2012-10-31|High current transformer with at least four splice points|

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ES15152081.4T| ES2592680T3|2011-10-31|2012-10-31|Procedure for manufacturing a high voltage transformer|

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EP15152081.4A| EP2913136B1|2011-10-31|2012-10-31|Method of producing a high voltage transformer|

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CN201280064964.1A| CN104010758B|2011-10-31|2012-10-31|There is the strong current transformer of Multi-contact, transformer element, contact plate and secondary windings and for the method manufacturing this strong current transformer|

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PL15152081.4T| PL2913136T3|2011-10-31|2012-10-31|Method of producing a high voltage transformer|

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JP2015159589A| JP6002295B2|2011-10-31|2015-08-12|High current transformer, transformer element, contact plate, and secondary winding, and method of manufacturing such a high current transformer|

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US15/205,809| US10325720B2|2011-10-31|2016-07-08|Method for producing a heavy-current transformer|