Method of determining interference coupling between welding circuits of a welding system

Abstract

The invention relates to a method for determining an interference coupling between welding circuits (2-i) of a welding system (1), comprising the following steps: applying (S1) a predetermined current profile (SP) in a first welding circuit (2-1) of the welding system (1); detecting (S2) a voltage progression and / or a current progression induced thereby in a second welding circuit (2-2) of the welding system (1); and determining (S3) the interference coupling on the basis of the current profile (SP) of the current applied in the first welding circuit (2-1) and the voltage progression and / or the current progression detected in the second welding circuit (2-2).

Description

Technical Field

[0001] The present invention relates to a method for determining interference coupling between welding circuits in a welding system and a method for compensating for such interference coupling. Background Technology

[0002] A welding system may include one or more welding circuits that can be used to weld at least one workpiece. Each welding circuit has a welding power source that provides welding current for welding the workpiece. The welding power source supplies current to a fusible wire electrode in the welding circuit, generating an electric arc between the tip of the wire electrode and the surface of the workpiece. Depending on the variation of the welding method and the welding parameters used, the wire electrode is melted by the electric arc in different ways.

[0003] During pulsed arc welding, the increased pulse voltage is regularly superimposed on the base voltage, resulting in the base current and pulse current alternating at a predetermined frequency and pulse duration.

[0004] Figure 1 This illustrates the schematic current progression over time t during pulse welding. Figure 1 As can be seen, in this welding process, the welding current I is increased to a high value in a pulsed pattern. Material delivery into the molten pool is based on the current pulses. During the basic current phase, the arc burns at low power, the additional material or welding wire electrode is melted, and the weld pool remains liquid. During the pulse phase, droplets are formed, which are released through magnetic contraction. In pulsed arc welding, the introduction of heat to the workpiece can be reduced and controlled. As a result, relatively thick welding wire electrodes can be used to weld thin workpiece plates, the melting power during welding is higher, and spatter can be greatly reduced.

[0005] Figure 1 The progression of the welding current level in the middle shows the basic current amplitude I. g and for pulse duration t p The amplitude of the current pulse I p A current pulse is applied at a pulse frequency f based on the period duration T. Figure 1 The average welding current I is also shown. av .

[0006] Figure 2 The diagram illustrates a period of time during the pulse welding process. The arc initially (t1) burns at a low basic current level. As the current increases (t2), the wire tip of the welding wire electrode begins to melt. Once the current reaches the pulse current value I (t3), the process is complete. pThe tip of the welding wire electrode is intensely melted and forms a droplet. This droplet contracts due to magnetic compression. Subsequently, the current is reduced (t4) to a lower value, causing the droplet to contract further and accelerate towards the molten pool. At time t5, the droplet has been released from the tip of the welding wire electrode. Figure 2 As can be seen, the welding current I was subsequently reduced again (t6) to the basic current value.

[0007] Figure 3 The conventional welding circuit SSK of a welding system is shown. The welding circuit SSK includes all the wires and connections from the positive to the negative terminal of the welding power source SSQ. The welding current I flows through the welding circuit SSK. Figure 3 As illustrated, the forward and reverse conduction of the welding circuit SSK is affected by resistance R and inductance L, respectively. The welding circuit resistance R consists of the sum of the resistances of all wires and connectors through which the welding current I flows. The welding circuit resistance R can be further subdivided into the following sub-resistances: the resistance of the grounding wire RL-, the resistance of the wire passing through the cable assembly RL+, and the transition resistance at the terminal connectors. The resistance of the welding wires (in other words, the resistance of the grounding wire and the resistance of the wire passing through the cable assembly) is determined by the cross-section of the wires and the conductor material, and does not change under normal circumstances. Conversely, the transition resistance of the terminal connectors can change relatively significantly, for example, due to oxidation or loosening of the terminal connectors.

[0008] The welding circuit inductance L of the welding circuit SSK should be understood as the characteristic of the welding circuit to resist every change in current with dynamic resistance. The larger the welding circuit inductance of the welding circuit SSK, the larger this dynamic resistance.

[0009] In welding circuit SSK, both the welding circuit resistance R and the welding circuit inductance L affect the welding process. For example, if the welding circuit resistance R changes, the arc length will change.

[0010] In addition, such as Figure 4 As shown, the change in inductance L of the welding circuit affects the welding process. Figure 4The voltage progression at the arc LB and the output jack of the welding power source during pulse welding, as well as the progression of the welding current I over time, are illustrated. Various types of modulation can be used in this welding method, particularly Ig / Ip modulation and Ig / Up modulation. In Ig / Ip modulation, the welding current I precisely corresponds to a predetermined target value for the welding current at each moment within a time period. Therefore, if the current increases from the base current to the pulse current, the necessary voltage required to drive the current through the welding circuit inductor L is automatically set. This is advantageous over Ig / Up modulation because the welding circuit inductor L does not affect the current rise. Conversely, in Ig / Up modulation, the current rise varies with the welding circuit inductor L of the welding circuit SSK because the pulse voltage of this modulation remains constant. However, in Ig / Ip modulation, the rate of current rise remains constant only if the welding power source SSQ of the welding circuit SSK provides sufficient voltage. However, if the sum of the individual voltages in the welding circuit SSK exceeds the maximum output voltage of the welding power source SSQ, this threshold is met. In this case, the welding current rises more slowly, altering the welding process.

[0011] Figure 5 The diagram schematically illustrates the voltage composition in a conventional soldering circuit SSK. Voltage U a (In other words, the voltage at the power supply output terminal) is determined by the voltage U. sk U L and U puls Composition, in which

[0012]

[0013]

[0014] And U puls It is independent of the protective gas, materials, and arc length used.

[0015] Voltage U sk With welding circuit resistance R and pulse current I p Irrelevant.

[0016] Voltage U L It depends on the inductance L and the rate of change of current di / dt.

[0017] like Figure 6As illustrated, if multiple welding power sources SSQ are used in a welding system, coupling occurs between welding circuits SSK. The current lines of the welding power sources SSQ form conductive loops around specific areas. Whenever two fields or areas of this type overlap, if the current I in one conductive loop changes, a voltage U is induced in the second conductive loop. The more the two areas or fields overlap, and the smaller the distance between the two fields or loops, the larger the induced current U. The behavior of the various welding currents SSK in a welding system is somewhat like that of a poorly coupled transformer.

[0018] The coupling between the welding currents SSK in a welding system affects the process behavior during welding. For each current pulse applied to the welding circuit SSK, a voltage U is induced in the line of the other welding circuit SSK. This occurs in both directions, or bidirectionally. The voltage U induced in the welding circuit SSK causes a current flow in the other welding power source, which acts like a resistance change in the arc LB. Figure 6 As illustrated in the diagram, in the welding circuit SSK, an additional voltage source is switched on to some extent and controlled by another welding power source SSQ. Because the two welding power sources SSQ operate asynchronously, and particularly have different pulse frequencies, fluctuations or jerks in the arc length may occur. This is most noticeable at small differences in pulse frequency.

[0019] To minimize the mutual interference between welding circuits SSK in a welding system, it is traditionally attempted to minimize the induction zone of each circuit SSK by arranging the lines of the welding circuit SSK in close parallel. Furthermore, it is traditionally attempted to spatially separate the welding circuit SSK.

[0020] However, in many cases, this traditional process is practically impossible because the main production conditions make it impossible to properly arrange the lines of the different welding circuits SSK in the welding system. Furthermore, in many cases, there is neither the knowledge nor the awareness to properly arrange the lines of the welding circuits SSK. Moreover, even if the lines of the welding circuits SSK are properly arranged, it is almost impossible to estimate the extent to which this reduces the coupling between the welding circuits SSK and the extent to which the remaining residual coupling still adversely affects the welding process on the workpiece WS. Summary of the Invention

[0021] Therefore, the object of the present invention is to provide a method for determining interference coupling between welding circuits in a welding system.

[0022] Therefore, the present invention provides a method for determining interference coupling between welding circuits in a welding system, the method comprising the following steps:

[0023] A predetermined current profile is applied in the first welding circuit (welding transmission circuit) of the welding system.

[0024] Detecting the voltage and / or current processes induced in at least one second welding circuit (welding receiving circuit) of the welding system; and

[0025] Interference coupling between the sending and receiving welding circuits is determined based on the current distribution applied in the first welding circuit (sending welding circuit) and the voltage and / or current processes detected in the second welding circuit (receiving welding circuit).

[0026] In one feasible embodiment of the method according to the invention for determining interference coupling between welding circuits in a welding system, the individual welding circuits of the welding system are closed to determine interference coupling between the welding circuits. For this purpose, the welding torch nozzle (contact tube) may be short-circuited with the workpiece in each case.

[0027] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits in a welding system, the current distribution applied in the first welding circuit (transmitting welding circuit) has one or more current pulses.

[0028] In another feasible embodiment of the method for determining interference coupling between welding circuits of a welding system according to the present invention, the ohmic portion of the coupling between welding circuits of the welding system is determined in at least one first measurement window based on the current distribution applied in the first welding circuit (transmitting welding circuit) and the voltage and / or current processes detected in the second welding circuit (receiving welding circuit), and the inductive portion of the coupling between welding circuits of the welding system is determined in at least one second measurement window.

[0029] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits in a welding system, the first measurement window is in a phase where the applied current distribution in the first welding circuit (transmitting welding circuit) is constant.

[0030] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, the second measurement window is located in the phase where the applied welding current level rises during the rising edge of a current pulse or falls during the falling edge of a current pulse in the first welding circuit (the welding transmission circuit).

[0031] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, a coupling factor is calculated, which represents the ohmic portion and / or the inductive portion coupled between welding circuits of the welding system.

[0032] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, the calculated ohmic coupling factor representing the ohmic portion of the coupling between welding circuits and the calculated inductive coupling factor representing the inductive portion of the coupling between two welding circuits are stored in the data memory of the welding power supply of the welding circuit of the welding system.

[0033] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits in a welding system, the calculated ohmic coupling factor and the calculated inductive coupling factor are output to the user via the user interface of the welding system.

[0034] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, voltage and / or current processes detected in a second welding circuit (receiving welding circuit) are stored in the data memory of the second welding circuit.

[0035] Preferably, for this purpose, the induced voltage values ​​(in other words, the voltage values ​​measured by the receiving power supply) for each applied current amplitude and current change rate of the transmitting power supply are stored in tabular form in the receiving power supply in each case.

[0036] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, the current distribution applied in the first welding circuit (transmitting welding circuit) is stored in the data memory of the second welding circuit (receiving welding circuit), or transmitted from the first welding circuit to the second welding circuit wirelessly or wiredly via a communication connection.

[0037] If synchronization occurs during startup, a modified current distribution stored in the receiving power supply of the receiving welding circuit can be used. In other words, while determining the coupling voltage, a trigger pulse is pre-generated by the transmitting power supply, allowing the stored current distribution (table) to be assigned to the voltage measurement results. Therefore, to generate the voltage values ​​in the table, this modification does not require sending the current distribution directly to the receiving source.

[0038] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, the welding circuits of the welding system are initially synchronized with each other to determine interference coupling between the welding circuits.

[0039] In another feasible embodiment of the method according to the invention, the calculated and stored coupling factor is used to determine the compensation voltage based on the current distribution of the current distribution applied in another welding circuit.

[0040] In another feasible embodiment of the method according to the invention for determining interference coupling between welding circuits of a welding system, a compensation voltage is subtracted from the measured voltage measured by a voltage measuring unit of a welding power source located in the welding circuit to determine an adjusted measured voltage used to adjust the welding current generated by the welding power source.

[0041] The present invention also provides a welding system including welding circuits for simultaneously welding one or more workpieces, the welding system having a coupling determination unit that determines interference coupling between welding circuits by means of a method for determining interference coupling between welding circuits of the welding system, the method comprising the following steps:

[0042] A predetermined current distribution is applied in the first (transmitting) welding circuit of the welding system;

[0043] Detecting the voltage and / or current processes induced in the second (receiving) welding circuit of the welding system; and

[0044] Based on the current distribution of the current applied in the first (transmitting) welding circuit and the voltage and / or current processes detected in the second (receiving) welding circuit, interference coupling between the (transmitting) and (receiving) welding circuits of the welding system is determined.

[0045] Another objective of this invention is to reduce or compensate for interference coupling between welding circuits in an initially determined welding system.

[0046] Therefore, in another aspect, the present invention provides a method for compensating for interference effects from another welding power source (transmitting welding power source) on the welding current provided by a welding power source (receiving welding power source) for welding a workpiece, the compensation method comprising the following steps:

[0047] A compensation voltage is provided, which is calculated based on the welding current process provided by another welding power source (the transmitting welding power source);

[0048] The corrected measurement voltage is determined by subtracting the compensation voltage from the measurement voltage measured by the voltage measurement unit of the welding power source (receiving the welding power source); and

[0049] The welding current generated by the welding power source (receiving the welding power source) is adjusted according to the calibrated measured voltage.

[0050] In the compensation method according to the invention for compensating for interference effects from another welding power source (transmitting welding power source) used for welding the same or different workpieces, which is provided by a welding power source (receiving welding power source) for welding workpieces, the compensation voltage is calculated based on the current distribution of the welding current process provided by the other welding power source (transmitting welding power source) and the stored coupling factor.

[0051] In another feasible embodiment of the compensation method according to the invention, the stored coupling factor includes an ohmic coupling factor and at least one inductive coupling factor.

[0052] In another feasible embodiment of the compensation method according to the invention, the current distribution of the welding current process of another welding power source (transmitting welding power source) is read from the current distribution memory or data memory of the welding power source (receiving welding power source).

[0053] Therefore, it is preferable to properly synchronize the current process of the transmitting welding power source with the current process data stored in the receiving welding power source.

[0054] In another feasible embodiment of the compensation method according to the invention, the current distribution of the welding current process of another welding power source (transmitting welding power source) is transmitted wirelessly or wired to the computing unit of the welding power source (receiving welding power source).

[0055] In another feasible embodiment of the compensation method according to the invention, the current distribution of the welding current process of another welding power source (transmitting welding power source) includes the current level and the change of the current level with respect to the relevant time value.

[0056] In another feasible embodiment of the compensation method according to the invention, the calculation unit of the welding power source (receiving welding power source) continuously subtracts the compensation voltage calculated by the calculation unit of the welding power source (receiving welding power source) from the measured voltage measured by the voltage measurement unit of the welding power source (receiving welding power source) to determine the corrected measured voltage.

[0057] In another feasible embodiment of the compensation method according to the invention, the welding current regulated by the regulating unit using the corrected measuring voltage is supplied to the welding torch for welding the workpiece via the welding current line of the welding power source (receiving the welding power source).

[0058] In another aspect, the present invention provides a welding power source for generating a welding current that can be supplied to a welding torch for welding a workpiece via a welding current line, the welding power source having:

[0059] A calculation unit suitable for calculating a compensation voltage based on the welding current progression of another welding power source used for welding the same or different workpieces, and

[0060] A compensation unit is adapted to subtract a compensation voltage calculated by a calculation unit from a measured voltage measured by a voltage measurement unit of the welding power source to determine a corrected measured voltage, which is used by an adjustment unit of the welding power source to adjust the welding current generated by the welding power source.

[0061] In one feasible embodiment of the welding power source according to the invention, the calculation unit of the welding power source calculates the compensation voltage based on the current distribution of the welding current provided by another welding power source (the transmitting welding power source) and the coupling factor stored in a data storage device or database.

[0062] In another feasible embodiment of the welding power source according to the invention, the current distribution of the welding current of the other welding power source (the transmitting welding power source) includes the current level and the variation of the current level with a relevant time value.

[0063] In another feasible embodiment of the welding power source according to the invention, the current distribution of the welding current of another welding power source is received from the other welding power source (the transmitting welding power source), or read synchronously from the current distribution memory of the welding power source.

[0064] In another feasible embodiment of the welding power source according to the invention, the calculation unit of the welding power source provided for calculating the compensation voltage has:

[0065] The first multiplier multiplies the current level in the current distribution by the ohmic coupling factor to calculate the ohmic component of the compensation voltage.

[0066] The second multiplier multiplies the current level change in the current distribution by the inductive coupling factor to calculate the inductive portion of the compensation voltage; and

[0067] An adder adds the ohmic and inductive portions of the compensation voltage to calculate the compensation voltage.

[0068] The present invention also provides a welding system comprising at least two welding power sources that operate in conjunction to weld one or more workpieces.

[0069] Each welding power source is provided to generate welding current, which can be supplied via a welding current line to a welding torch for welding one or more workpieces. Each welding power source has:

[0070] The calculation unit is suitable for calculating the compensation voltage based on the welding current progression of another welding power source in the welding system, and

[0071] A compensation unit is adapted to subtract a compensation voltage calculated by a calculation unit from a measured voltage measured by a voltage measuring unit of a welding power source to determine a corrected measured voltage, which is used by an adjustment unit of the welding power source to adjust the welding current generated by the welding power source. Attached Figure Description

[0072] In the following description, possible embodiments of various aspects of the invention will be described in more detail with reference to the accompanying drawings, in which:

[0073] Figure 1 This illustrates the current flow during a traditional pulse welding process;

[0074] Figure 2 It shows Figure 1 The current flow over a period of time during the pulse welding process shown;

[0075] Figure 3 This is a schematic diagram of a traditional soldering circuit;

[0076] Figure 4 The voltage and current progression over a period of time is shown in a conventional pulse welding process;

[0077] Figure 5 This is a schematic diagram illustrating the voltage configuration in a traditional welding circuit;

[0078] Figure 6 This is a schematic diagram of the coupling between different welding circuits, illustrating the fundamental technical problem of the present invention;

[0079] Figure 7 This is a simplified flowchart illustrating an embodiment of a method for determining interference coupling between welding circuits in a welding system according to a first aspect of the present invention;

[0080] Figure 8A , Figure 8B This is a schematic diagram of a welding system including two welding circuits, showing... Figure 7 The operating mode of the method for determining interference coupling between welding circuits in a welding system according to the present invention is shown.

[0081] Figure 9 This is another schematic diagram of a welding system including two welding circuits, showing... Figure 7 The method shown is for determining interference coupling between welding circuits in a welding system according to the present invention.

[0082] Figure 10 The signal process is shown, which demonstrates Figure 7The illustrated method for determining interference coupling between welding circuits in a welding system according to the present invention is a feasible embodiment.

[0083] Figure 11 Another signal process is shown, which demonstrates Figure 7 The operating mode shown is an operational mode in a feasible implementation of a method for determining interference coupling between welding circuits in a welding system.

[0084] Figure 12 This is a flowchart illustrating a feasible embodiment of a method according to another aspect of the present invention for compensating for interference effects from another welding power source used for welding the same workpiece, which is provided by a welding power source for welding the workpiece.

[0085] Figure 13 The signal process is shown, which demonstrates Figure 12 The operational mode of the implementation of the communication method shown;

[0086] Figure 14 This is a schematic diagram illustrating the coupling effect between two circuits in a welding system;

[0087] Figure 15 This is a schematic diagram of a power supply without coupling compensation according to the present invention;

[0088] Figure 16A and Figure 16B It is based on Figure 12 The diagram shows a power supply with coupling compensation according to the present invention, illustrating the compensation method. Detailed Implementation

[0089] The method or apparatus according to the invention is used to reduce or eliminate mutual interference between welding power sources operating simultaneously in a welding system. To this end, in a first aspect of the invention, existing interference couplings between welding circuits in the welding system are first identified. In another aspect of the invention, the identified interference is subsequently compensated.

[0090] Figure 7 This is a flowchart illustrating an embodiment of a method for determining interference coupling between welding circuits 2-1 and 2-2 of welding system 1 according to a first aspect of the present invention. Figure 8A and Figure 8B The example illustrates this welding system 1.

[0091] exist Figure 7 In the embodiment shown, the method according to the invention for determining interference coupling between welding circuits 2-1 and 2-2 of welding system 1 basically includes three steps.

[0092] In the first step S1, a predetermined current distribution is applied to the first welding circuit 2-1 (welding circuit) of the welding system 1.

[0093] In another step S2, the voltage process U(t) and / or current process I(t) induced in the second welding circuit 2-2 (welding circuit) of the welding system 1 are detected.

[0094] Finally, in step S3, based on the current distribution SP of the current applied in the first welding circuit 2-1 (transmitting welding circuit) and the voltage and / or current processes detected in the second welding circuit 2-2 (receiving welding circuit), interference coupling between welding circuits 2-1 and 2-2 (i.e., between the transmitting welding circuit and the receiving welding circuit) is determined.

[0095] Figure 8A and Figure 8B The welding system 1 is illustrated by way of example, which includes two welding circuits 2-1 and 2-2 for simultaneously welding workpiece 3. For example... Figure 8A and Figure 8B As shown, the two welding circuits 2-1 and 2-2 each include welding power sources 4-1 and 4-2. In each case, current I can be supplied to workpiece 3 via power supply lines 5-1 and 5-2. Furthermore, as... Figure 8A and Figure 8B As shown, the current I in each welding circuit 2-1, 2-2 returns to the welding power supply 4-1, 4-2 of the corresponding welding circuit 2-1, 2-2 via the associated return line or ground line 6-1, 6-2 in each case. The power supply line 5-i and the drain line 6-i of welding circuit 2-1 are respectively connected to the electrodes 12a, 12b of the welding power supply 4-i of welding circuit 2-1.

[0096] like Figure 8A and Figure 8B As shown, the two welding circuits 2-1 and 2-2 of welding system 1 are preferably closed to determine interference coupling between the welding circuits. Figure 8A and Figure 8B The circuit arrangement shown is suitable for determining interference coupling between welding circuit 2-1 of welding system 1 and second welding circuit 2-2 of welding system 1. Therefore, in the first step S1, as... Figure 8A and Figure 8B As schematically shown, a predetermined current distribution SP is first applied in one of the two welding circuits of the welding system 1 (e.g., in the first welding circuit 2-1). The current distribution SP applied in the first welding circuit 2-1 preferably has one or more current pulses. Figure 8A and Figure 8BAs schematically shown, in the welding power supply 4-2 of another welding circuit 2-2, the induced voltage process U is detected and stored. Therefore, in step S2, the voltage process and / or current process induced in the second welding circuit 2-2 of the welding system 1 is detected and / or stored. Subsequently, in the welding power supply 4-2, based on the current distribution SP of the current I applied in the first welding circuit 2-1 and the voltage process U and / or current process detected in the second welding circuit 2-2 by means of the detector unit or the measuring unit 8-2, interference coupling between welding circuits 2-1 and 2-2 is determined or calculated. In this case, the ohmic portion and the inductive portion coupled between welding circuits 2-i of the welding system 1 are determined or calculated. In a preferred embodiment, the ohmic portion coupled between welding circuits 2-i of the welding system 1 is determined in at least one first measuring window MF1, and the inductive portion coupled between welding circuits 2-i of the welding system 1 is determined in at least one second measuring window MF2. Also as Figure 10 As shown, the first measurement window MF1 for determining the ohmic portion of the coupling is located within the current distribution SP applied in the first welding circuit 2-1, where the current level of the applied current I is constant. The second measurement window MF2 for determining the inductive portion of the coupling between welding circuits 2-i is preferably located within the current distribution applied in the first welding circuit 2-1, where the current level of the applied current rises during the rising edge of the current pulse or falls during the falling edge of the current pulse. Figure 10 The measurement window MF2 for determining the coupled inductive portion during the rising edge of the current pulse is shown. Preferably, the inductive portion of the measured voltage U2 is calculated by determining the voltage-time region at the welding power source 4-2 during the current change at the sending welding power source 4-1 and subtracting the ohmic voltage portion therefrom. Preferably, the average voltages of the coupled inductive and ohmic portions are calculated and evaluated separately from each other. Preferably, the coupling factor K is calculated. R K L This represents the ohmic portion and the inductive portion coupled between welding circuits 2-1 and 2-2 in welding system 1. In one feasible embodiment, the calculated ohmic coupling factor K, representing the ohmic portion coupled between welding circuits 2-1 and 2-2, is used... R and the calculated inductive coupling factor K representing the inductive portion of the coupling between welding circuit 2-i L The data is stored in the data storage devices 9-1 and 9-2 of the welding power sources 4-1 and 4-2 in welding system 1. In one feasible embodiment, the calculated ohmic coupling factor K is... R and the calculated inductive coupling factor K L Output to the user of welding system 1 via the user interface.

[0097] Reflected in the Ohmic coupling factor K R The ohmic component of the coupling indicates whether there is a wire portion in the two soldering circuits 2-1 and 2-2 through which currents from the two power supplies 4-1 and 4-2 are flowing. The ohmic component of the coupling is R. Koppel Preferably expressed in milliohms.

[0098] R Koppel = U Empfänger / I Sender ,

[0099] Where R Koppel It is the resistance of the common line section of the two soldering circuits 2-1 and 2-2, U. Empfänger It is the voltage detected on the receiving side by the receiving welding power source 4-2, and I Sender It is the current I1 applied in the welding circuit 2-1.

[0100] Common wire portions in the two soldered circuits 2-1 and 2-2 should be avoided; in other words, efforts should be made to keep the ohmic portion of the coupling as low as possible.

[0101] The inductance of the coupling between the two welding circuits 2-1 and 2-2 reflects the spatial arrangement of the two welding circuits relative to each other, and in particular the distance between the two welding circuits, and is expressed in millihenries.

[0102] L kopp =U empf_ind / (di / dt Sender ),

[0103] Where L kopp Represents coupled inductance.

[0104] U empf_ind It is the voltage U2 induced at the receiving welding circuit 2-2, and di / dt Sender This represents the change in current I1 that occurs at the welding circuit 2-1.

[0105] The determined value of the coupling measurement (in other words, the inductive and ohmic components coupled between welding circuits 2-i) is preferably calculated by the calculation unit 7-i and, in a feasible implementation, output to the user of welding system 1 via a user interface. In a feasible implementation, the calculated coupling inductance L Koppel This relates to the inductance L1 of the welding circuit 2-1, and can be displayed to the user, for example, as a percentage. The advantage of this is that it is easier to understand via a user display, as millihenries are relatively difficult for users to grasp and can easily be confused with conventional welding circuit inductances. The relative coupling inductance (l) expressed as a percentage... Koppel =LKoppel / L) is easier to understand intuitively, relative to the coupled inductance l Koppel The ideal value is 0%, in other words, there is no coupling between welding circuits 2-i.

[0106] In one feasible implementation, the coupled ohmic portion R Koppel It can also be related to the sending welding circuit 2-1 (r) Koppel =R Koppel / R). The relative ohmic part r Koppel The value r Koppel A value >0% indicates that there is a common line section between the two soldered circuits 2-1 and 2-2, through which currents I1 and I2 are flowing. This should be avoided. Therefore, the aim should be to make the relative ohmic portions of the coupling r... Koppel The value is 0%.

[0107] In one feasible embodiment of the welding system 1, a wireless or wired communication connection KV exists between the welding power source 4-1 of the first welding circuit 2-1 and the welding power source 4-2 of the second welding circuit 2-2. In this embodiment, the current distribution SP provided by the first welding power source 4-1 of the welding system 1 in the first welding circuit 2-1 is transmitted to the welding power source 4-2 via the communication connection KV. In the second welding circuit 2-2, the induced voltage and / or current processes are detected. In another step, the interference coupling between the two welding circuits 2-1, 2-2 can then be determined or calculated by the calculation unit 7 based on the current distribution SP of the current I applied in the first welding circuit 2-1 transmitted or sent via the communication connection KV and the voltage and / or current processes detected in the second welding circuit 2-2.

[0108] In an alternative embodiment, there is no communication connection KV, and no data exchange occurs between the two welding power sources 4-1 and 4-2 of the two welding circuits 2-1 and 2-2 of welding system 1. Even without a data connection between the two welding power sources 4-1 and 4-2, the coupling factor KF can still be calculated or the interference coupling between welding circuits 2-1 can be determined. In this embodiment, the necessary data is already stored in the data memory 9-2 of the receiving welding power source 4-2. In this variant configuration, the current distribution SP (di / dt / current level and time value) stored in the data memory 9-1 of the transmitting welding power source 4-1 is also stored in the data memory 9-2 of the receiving welding power source 4-2. As a result, the calculation unit 7-2 present in the receiving welding power source 4-2 can perform the calculation of the inductive coupling factor KF. L and Ohmic coupling factor K RThe calculation is performed without the need for data exchange between the two welding power sources 4-1 and 4-2 via the communication connection KV. In this embodiment, the current distribution SP applied in the first welding circuit 2-1 is also stored in the data memory 9-2 of the second welding circuit 2-2, and can be used to calculate the corresponding compensation voltage U. Komp .

[0109] In one feasible implementation, the start time of the applied current distribution SP can be detected by measuring the voltage change at the receiving welding power source 4-2 using the measurement signal measured by its measurement unit 8-2, making it possible to synchronize the various stages or measurement windows MF. This is feasible because the time distribution or current distribution SP of the transmitting welding power source 4-1 is stored in the data memory 9-2 at the receiving welding power source 4-2.

[0110] In one feasible implementation, a first number of transmitter synchronization cycles can be initiated, with a relatively steep current rise (di / dt) to synchronize the receiver or detector 8-2 receiving the welding power supply 4-2, even in cases of weak coupling between the welding circuits 2-i. In subsequent time windows, the actual measurement distribution sequence can then be initiated.

[0111] exist Figure 8A In the embodiment of the welding system 1 shown, the two welding circuits 2-1 and 2-2 are short-circuited via workpiece 3, and there is no common wiring portion, particularly via workpiece 3. Figure 8B In the embodiment of the welding system 1 shown, two welding circuits 2-1 and 2-2 are provided for welding two different workpieces 3-1 and 3-2. Figure 9 In the illustrated embodiment, the two welding circuits 2-1 and 2-2 share a common line portion because the grounding or return line 6-2 of the second welding circuit 2-2 branches at node K of the grounding or return line 6-1 of the first welding circuit 2-1. Therefore, Figure 9 The common line portion shown includes a portion of the grounding wire 6-1 of the first welding circuit 2-1 and the wire connection via workpiece 3. This is reflected in the ohmic coupling factor K. R The ohmic part R of the measured coupling in Koppel This indicates the existence of this type of shared line.

[0112] The calculated coupling factor K L K R It can be stored and, in one feasible implementation, can be used to determine the compensation voltage U based on the current distribution SP of the current I1 applied to the first welding circuit 2-1. Komp In one feasible implementation, the voltage U is measured during the welding operation. Mess(Preferably measured by the voltage measuring unit 8-1 of the welding power source 4-1 located in the first welding circuit 2-1) minus the determined compensation voltage U Komp In order to determine the corrected measurement voltage U' Mess The corrected measurement voltage can be used to regulate the welding current I generated by welding power source 4-1 during the welding operation. S .

[0113] Figure 10 The signal process of the measurement cycle in the welding system 1 according to the invention is illustrated by way of example. In the example shown, multiple (e.g., 20) measurement cycles of this type are output by sending welding power 4-1 at intervals of 30 ms, for example, and the measurement values ​​t0 to t1 (MF2) and t2 to t3 (MF1) of each cycle are averaged.

[0114] exist Figure 10 In the diagram, curve I shows the current flow I1 in the transmitting welding circuit 2-1. Curve II shows the voltage flow U1 in the transmitting welding circuit 2-1. Curve III shows the voltage flow U2 in the receiving welding circuit 2-2. Figure 10 As can be seen, between times t2 and t3, the level of the current distribution SP applied by the welding power source 4-1 of the first welding circuit 2-1 is constant, forming a measurement window MF1 for determining the ohmic portion of the interference coupling between the two welding circuits. The ohmic portion of the coupling between the two welding circuits 2-1 and 2-2 of the welding system 1 can be determined within the first measurement window MF1. This first measurement window MF1 is located in the phase where the level of the applied current I1 in the current distribution SP applied in the welding circuit 2-1 is constant.

[0115] Conversely, between times t0 and t1 (MF1), the inductive portion coupled between welding circuits 2-i of welding system 1 is determined. For example... Figure 10 As shown, a second measurement window MF2 is formed during the time interval between t0 and t1, in which the level SP of the applied current I1 rises relatively strongly during the rising edge of the current pulse. The inductance portion coupled between the welding circuits 2-1 of the welding system 1 is determined in the second measurement window MF2 based on the current distribution SP applied in the first welding circuit 2-1 and the voltage and / or current processes determined in the second welding circuit 2-2. The second measurement window MF2 is located in the phase where the level of the applied current I1 rises during the rising edge of the current pulse in the current distribution SP applied in the first welding circuit 2-1. Alternatively, the second measurement window MF2 may also be located in the phase where the level of the applied current I1 falls during the falling edge of the current pulse in the current distribution SP applied in the first welding circuit 2-1. Figure 10It can be seen that the determination or measurement of the coupled ohmic portion is carried out in a different measurement window MF than the determination of the coupled inductive portion.

[0116] In one feasible implementation, the current measurement window (MF1) can be used as a reference. n The transmitter current I1 flowing in the first welding circuit 2-1 and in the previous cycle at t2 and t3 (MF1) n-1 The resistance is determined during the phases between t0 and t1 to calculate the ohmic voltage portion, and this ohmic voltage portion is subtracted from the measured value. For example, a measured value is stored every 25µs, and the ohmic voltage portion is subtracted from it. The individual measured values ​​for which the ohmic portion has been subtracted can be added together during the phases t0 and t1 (the second measurement window MF2). Thus, the arithmetic mean can be calculated at the end of t1. Subsequently, based on the arithmetic mean of the phases, the average value for multiple cycles (e.g., 20 cycles) can be calculated.

[0117] Based on the calculated average voltage U empf_ind In a feasible implementation, the coupling inductance K can be calculated using the following formula, considering the current change di / dt during the transmitter current process. L :

[0118] L kopp =U empf_ind / (di / dt Sender )

[0119] Figure 11 This type of measurement cycle is illustrated by an example.

[0120] In one feasible implementation, a synchronization sequence occurs after the welding system 1 is activated by the user, prior to the actual coupling factor measurement, in which the welding power supply 4-1 is set to transmit. For example, this type of synchronization sequence can be initiated by pressing a button on the aforementioned welding power supply 4-1.

[0121] Therefore, the welding power supply 4-1 feeds a current pulse (transmitter start pulse) with a rising gradient of, for example, 1000A / ms and a target current of 500A to the short-circuited welding circuit 2-1.

[0122] A voltage U2 is induced in the short-circuited receiving welding circuit 2-2 via magnetic coupling. The level of this voltage depends on the wiring arrangement of the two welding circuits 2-1 and 2-2 and is measured by its measuring unit 8-2 at the output terminal of the receiving welding power supply 4-2. In one feasible embodiment, the transmitter start pulse can be detected at the receiving welding power supply 4-2 by evaluating the absolute voltage value or voltage progression, or by evaluating the rate of change over a predetermined time interval (in other words, differentially).

[0123] If the voltage U2 exceeds a preset value of, for example, 0.5V at the receiving welding power source 4-2, then in a feasible implementation, the same measurement timing scheme as that in the transmitting welding power source 4-1 can be initiated.

[0124] The rise in the transmitter welding current at the receiver can also be detected by detecting the voltage change du / dt in the voltage U induced in the receiving welding power source 4-2. For this purpose, the voltage difference can be calculated from the continuously detected voltage signals at 25 μs intervals, for example. For instance, if the voltage difference exceeds, for example, 0.2V, a measurement timing scheme identical to that in the transmitting welding power source 4-1 can be initiated.

[0125] In another feasible implementation, a combination of the two evaluation methods (in other words, a combination of absolute evaluation and differential evaluation) is feasible.

[0126] therefore, Figure 8A , Figure 8B , Figure 9 The welding system 1 shown has a coupling determination unit that determines interference coupling between welding circuits 2-1 and 2-2 of the welding system 1. In one feasible embodiment, one power supply 4-1 or both power supplies of the welding system 1 have this type of coupling determination unit or calculation unit 7-i. In an alternative embodiment, the coupling determination unit of the welding system 1 can be formed by a separate unit, which is preferably connected to each welding power supply 2-i of the welding system 1 and communicates with it via a wireless or wired communication connection KV. The coupling determination unit is configured to perform... Figure 7 The determination method shown.

[0127] Once it has been used Figure 7 The method shown determines the coupling factor K. L K R In this case, it is preferable to automatically compensate for the determined interference effect by means of a compensation method according to another aspect of the present invention. Figure 12 It is used for the welding current I supplied by the welding power source 4 for welding workpiece 3. S A flowchart of a feasible implementation of a compensation method for compensating for interference from another welding power source 4' used for welding the same workpiece 3.

[0128] exist Figure 12 In the embodiments shown, the compensation method according to the present invention includes three main steps.

[0129] In the first step S AIn the process, the calculation unit 7-2 of the (receiving) welding power source 4-2 calculates the compensation voltage U based on the welding current process of another welding power source 4-1 provided by another welding power source 4-1. komp The compensation voltage U komp The current distribution SP of the current process I1 provided by another welding power source 4-1 can be calculated by the calculation unit 7-2 of the welding power source 4-2 based on the current distribution SP and the stored coupling factor KF. Alternatively, the current distribution SP already exists in the local data memory 9-2 of the welding power source 4-2. The coupling factor KF includes the ohmic coupling factor K. R and at least one inductive coupling factor K L And, for example, stored in the data memory 9-2 of the welding power source 4-2. Alternatively, the compensation voltage U Komp Alternatively, it can be calculated by another (sending) welding power source 4-1 calculation unit 7-1, and then the calculated compensation voltage U is calculated. Komp The signal is transmitted (received) to the welding power source 4-2 via the communication connection KV.

[0130] In another step S B In the middle, the measured voltage U is obtained from the voltage measuring unit 8-2 of the welding power source 4-2. Mess Subtract from step S A The compensation voltage U calculated by the computing unit Komp To determine the corrected measurement voltage U' Mess In one feasible implementation, the compensation unit 10-2 of the welding power source 4-2 measures the voltage U from the voltage measuring unit 8-2 of the welding power source 4-2. Mess The compensation voltage U calculated by calculation unit 7-2 of welding power source 4-2 is continuously subtracted from the compensation voltage U. Komp Or the compensation voltage U transmitted via a communication connection Komp To determine the corrected measurement voltage U' Mess .

[0131] In another step S C In the middle, based on the corrected measured voltage U' Mess Adjust the welding current I generated by welding power source 4-2 S In one feasible implementation, by means of the calibrated measurement voltage U' Mess Adjusted welding current I S The welding current can be supplied to the welding torch 13-2 for welding the workpiece 3 via the welding current line 5-2 of the welding power source 4-2. In a feasible embodiment of the compensation method according to the invention, the welding current process I of another welding power source 4-1 is read from the data memory 9-2 of the welding power source 4-2. SThe current distribution SP. In one embodiment of the compensation method according to the present invention, the welding current process I of another welding power source 4-1. S The current distribution SP is transmitted wirelessly or wiredly from another welding power source 4-1 to the calculation unit 7-2 of welding power source 4-2 via communication connection KV. The calculation unit calculates the compensation voltage U based on the transmitted welding current process and the stored coupling factor KF. Komp During the welding process, there is also a current progression that is dynamically generated based on the process state (short circuit) and operates in an event-based rather than periodic manner. Therefore, in the compensation that occurs while the welding process is running, the transmitter current distribution is directly sent to the receiver to achieve proper compensation for the coupling voltage. Another welding power source 4-1 has a welding current variation I. S The current distribution SP preferably includes the current level and the change of the current level with respect to a relevant time value. The measured voltage U can then be obtained from the voltage measurement unit 8-2 of the welding power source 4-2 by the compensation unit 10-2 of the welding power source 4-2. Mess The compensation voltage U calculated by calculation unit 7-2 of welding power source 4-2 is continuously subtracted from the compensation voltage U. Komp To determine the corrected measurement voltage U' Mess The corrected measured voltage U' Mess This is then used to adjust the welding current I transmitted to the relevant welding torch SB via the welding current line of welding power source 4-2. S Therefore, according to Figure 12 The compensation method according to the present invention can eliminate unwanted induced voltages from the measurement signal. As a result, the mutual influence of welding circuits 2-i can be reduced or eliminated.

[0132] Therefore, according to Figure 12 The compensation method according to the invention obtains the previously determined and stored coupling factor KF, particularly at least one ohmic coupling factor K. R and one or more inductive coupling factors K L Preferably, in the compensation method according to the invention, the current distribution SP (in other words, the current process) and the rate of change of the current I output by another sending welding power source 4-1 (di / dt) are continuously or constantly transmitted to the receiving welding power source 4-2 via the communication connection KV.

[0133] Based on the current distribution data, in other words, based on the absolute current value (in amperes) and the rate of change of current di / dt (A / ms), using a predetermined coupling inductance L (mH) and ohmic coupling factor R (mΩ), the coupling voltage can be calculated using the following formula:

[0134]

[0135] The coupling voltage follows the temporal progression of the induced current distribution SP of the transmitter power supply 4-1, and can be used as a compensation voltage U. Komp The signed number is the voltage U measured by its measuring unit 8-2 at the output socket of the receiving welding power source 4-2. Mess The measured voltage U' is continuously subtracted from the induced voltage portion. Mess Subsequently, process adjustment 11-2 was used to receive welding power source 4-2. As a result, the mutual interference between welding circuits 2-1 and 2-2 was reduced or completely eliminated.

[0136] In a preferred embodiment, the compensation voltage U Komp The calculated and corrected measured voltage U' Mess The determination is performed digitally. In an alternative implementation, the compensation voltage U komp The calculated and corrected measured voltage U' Mess The determination was carried out through simulation.

[0137] Figure 13 In application Figure 7 The diagram shown illustrates the voltage progression at the receiving welding power source 4-2 before and after the compensation method according to the present invention.

[0138] Figure 13 Curve I in the figure shows the current flow at the point where the welding power source 4-1 is sent.

[0139] Curve II shows the voltage progression at the receiving welding power source 4-2 before the application of the compensation method according to the invention.

[0140] Figure 13 Curve III in the figure shows the voltage progression at the receiving welding power source 4-2 after the application of the compensation method according to the invention.

[0141] The method according to the invention for compensating for interference effects between at least two welding circuits 2-1, 2-2 is applicable not only to detection and compensation in welding circuits having a constant welding circuit inductance L or coupling factor, but also to welding circuits having a welding circuit inductance L(t) that varies with time. The welding circuit inductance L of welding circuit 2-i can vary with the amplitude of the current. This is the case, for example, when ferromagnetic material is present in welding circuit 2-i.

[0142] In one feasible embodiment of the method according to the invention, the inductive portion coupled between the welding circuits 2-i of the welding system 1 is detected within a measurement window MF, which is subdivided into smaller time intervals, and for each time interval, a corresponding inductance value L is determined and stored. iSubsequently, according to the compensation method of the present invention, in each case, the relevant current value I of the current current in the transmitting welding circuit 2-1 is retrieved from the local data memory. i The various stored sensing values ​​L i And use it to calculate the coupling voltage or compensation voltage U Komp .

[0143] Figure 14 A practical example of the coupling effect between two soldering circuits 2-1 and 2-2 is shown. In the illustrated embodiment, in Figure 14 In welding system 1, the grounding wires 6-1 and 6-2 of the welding circuits 2-1 and 2-2 branching at node K are placed approximately parallel to each other, so that magnetic coupling is induced when current flows through the grounding wires 6-1 and 6-2. The parallel grounding wires 6-1 and 6-2 are responsible for inductive (magnetic) coupling. The power supply lines 5-1 and 5-2 each supply welding current I to the welding torches 13-1 and 13-2. S .

[0144] Figure 15 The illustration schematically depicts two welding power sources SSQ without coupling compensation according to the compensation method of the present invention. Figure 15 As can be seen, the two welding circuits SSK are separate from each other. Each welding power supply SSQ has a voltage measurement unit UME and a current measurement unit IME, which supply the measured values ​​to the regulation unit RE. The regulation unit is connected to the power conversion control system PCC. The welding power supply SSQ includes a transformer T and a rectifier diode D.

[0145] In comparison, Figure 16A and Figure 16B The diagram schematically illustrates two welding power sources 4-1 and 4-2 in which a welding system 1 performing the compensation method according to the invention is shown. Figure 16A and Figure 16B Each of the two welding power sources 4-1 and 4-2 shown is used to generate welding current, which can be supplied to welding torches 13-1 and 13-2 via welding current lines to weld workpiece 3. Each of the two welding power sources 4-1 and 4-2 has calculation units 7-1 and 7-2 and compensation units 10-1 and 10-2. Furthermore... Figure 8A , Figure 8B As shown, calculation units 7-1 and 7-2 form part of welding power sources 4-1 and 4-2. The calculation unit 7-i of welding power source 4-i is adapted to calculate the voltage U caused by the welding current process of another welding power source used for welding the same workpiece 3 and measured by the measuring unit 8-i. Mess And the stored coupling factor KF is used to calculate the compensation voltage U. KompThe compensation unit 10-i of the welding power source 4-i is adapted to measure the voltage U measured by the voltage measuring unit 8-i of the welding power source 4-i. Mess Subtract the compensation voltage U calculated by calculation unit 7-i of welding power source 4-i from the middle. komp To generate the corrected measurement voltage U' Mess The corrected measured voltage U' Mess The regulating unit 11-i of the welding power source 4-i is used to regulate the welding current I generated by the welding power source 4-i. S .

[0146] The calculation unit 7-i of welding power source 4-i is preferably based on the welding current I provided by another welding power source. S The compensation voltage U is calculated using the current distribution SP and coupling factor KF. Komp The coupling factor KF is preferably stored in the data memory 9-i of the associated welding power source 4-i. Figure 16A and Figure 16B In the embodiment shown, the inductive coupling factor K L and Ohmic coupling factor K R These coupling factors KF are stored in the local data memory 9-2 of the second welding power source 4-2. These coupling factors KF can be read from the computing unit 7-1 of the first welding power source 4-1 via a communication interface. Alternatively, the coupling factor K... R K L It can also be stored locally in the two welding power sources 4-1 and 4-2. Furthermore, the stored coupling factor K can be read from the central data memory via a data network. R K L .

[0147] like Figure 16A and Figure 16B As shown, welding power supplies 4-1 and 4-2 each have dedicated computation units 7-1 and 7-2. In a preferred embodiment, each computation unit 7-1 and 7-2 has a first multiplier 7A, a second multiplier 7B, and an adder 7C. The first multiplier 7A of computation unit 7 multiplies the current current level I in the current distribution by the ohmic coupling factor K. R To calculate the ohmic part U of the compensation voltage. KompR The second multiplier 7B of the calculation unit 7 multiplies the current level change di / dt within the current distribution SP by the read inductive coupling factor K. L To calculate the inductance component U of the compensation voltage kompL The calculation unit 7-i of the welding power source 4-1 also includes an adder 7B-i in each case, which compensates for the ohmic portion U of the voltage. kompR and the inductor part of the compensation voltage U kompL Calculate the compensation voltage U by adding the two.komp .exist Figure 16A and Figure 16B In the embodiment shown, the compensation voltage U is determined in this way. Komp In each case, it is sent to another welding power source. For example... Figure 16A and Figure 16B As shown, each welding power source 4-1, 4-2 has a dedicated compensation unit 10-1, 10-2. The compensation unit 10 of the welding power source 4 is configured such that it obtains a compensation voltage U calculated by its own calculation unit or the calculation unit 7 of another welding power source. komp And the measured voltage U is obtained from the dedicated voltage measuring unit 8 of the welding power source 4. Mess Subtract the compensation voltage from the measured voltage to determine the corrected measured voltage U'. Mess The corrected measured voltage U' Mess The adjustment unit 11-i is applied to the welding power source 4 by the compensation unit 10-i, and is used to adjust the welding current I generated by the welding power source 4. S .

[0148] exist Figure 16A and Figure 16B In the embodiment shown, the compensation voltage U Komp The calculated compensation voltage is calculated by the computing unit of another welding power source 4' and sent. Alternatively, the compensation voltage U Komp Alternatively, the calculation can be performed by a dedicated computing unit 7 based on the current distribution SP transmitted by another welding power source 4' via a communication connection. Furthermore, in another alternative embodiment, the computing unit 7 of the welding power source 4 can read the known predetermined current distribution SP of the other welding power source 4' from the local dedicated data memory 9 of the welding power source 4, and can do so by means of a coupling factor K. R K L Calculate the compensation voltage or compensation voltage distribution based on the known predetermined current distribution SP, and the coupling factor K. R K is also read from the local dedicated data memory 9 of the welding power source 4. In another embodiment, the compensation voltage distribution is pre-calculated based on the coupling factor KF and the predetermined current distribution SP, and stored in the local data memory 9 of the welding power source.

[0149] exist Figure 16A and Figure 16B In the embodiment shown, the multipliers 7A and 7B and the adder 7C of the calculation unit 7 use a predetermined calculation formula to calculate the compensation voltage U. Komp and the corrected measured voltage U Mess In an alternative implementation, a stored lookup table (LUT) can be used instead of a stored and implemented calculation formula.

[0150] The voltage correction values ​​or compensation voltage distributions measured during coupling factor determination are stored in a lookup table (LUT). Within the LUT, the measured voltage (e.g., X-axis) is plotted against the associated current I (e.g., Y-axis) and the variation of the current (di / dt) (e.g., Z-axis).

[0151] When the compensation method is applied during welding, the current actual current value and actual current change of the other welding power source 4' are plotted on the Y and Z axes, and the relevant voltage value (X-axis) is read out and the internally measured voltage U is obtained. Mess Subtract from the middle.

[0152] Preferably, each coupling value (voltage of inductive coupling and ohmic coupling) is detected and stored in a lookup table (LUT). For example... Figure 9 As shown, the two welding circuits 2-1 and 2-2 can be short-circuited. For example, the transmitting welding power source 4-1 can operate a first current distribution within the range of 0 to 500 A at a rate of 50 A / ms. The receiving welding power source 4-2 measures its own current voltage as well as the current and current change values ​​of the transmitting welding power source 4-1, and inputs the measured voltage at the corresponding point in the lookup table (LUT). This process can then be repeated for other current distributions (e.g., 100 A / ms and 0 to 500 A to 1000 A / ms and 0 to 500 A).

[0153] In another step, actual compensation is performed during the welding process. When compensation is performed during welding, the current actual current value and the actual current change value of another welding power source are plotted on the Y and Z axes, and the relevant voltage value (X axis) is read out and subtracted from the internally measured voltage.

[0154] This compensation can be performed periodically, for example, at regular time intervals of 25 μs. The values ​​in the table between them are preferably obtained by linear interpolation.

[0155] The table below shows examples of coupling voltages (or compensation voltages) in volts for R_Koppel = 25mΩ and L_koppel = 20μH:

[0156]

[0157] Multiple LUTs (Look-Up Tables) may also exist, selected as needed. In a robotic gantry system, the coupling inductance may vary depending on the position of each robot that can be mounted on the track, as the positions of welding cables 5-1 and 5-2 relative to each other change. Therefore, a coupling factor or compensation voltage can be selected from another LUT based on the robot's position relative to each other. The coupling factor KF is then pre-determined at multiple robot positions fixed by the user. The selection of the LUT is preferably performed by the robot's control system.

[0158] As a result of the compensation method according to the invention, the quality of the welding process can be greatly improved, meaning that the weld produced in the welding process is improved in terms of quality because the interference from another welding power source used for welding the same workpiece 3 is reduced or compensated. The compensation method according to the invention can be performed digitally, but it can also be performed analogically. The compensation method according to the invention is particularly suitable for welding system 1 in which multiple welding power sources 4-i weld simultaneously in the system / unit. Voltage coupling occurring in this case results in the measured voltage U being used as a regulating variable. Mess Distortion. As a result of the compensation method according to the present invention, the measured voltage U Mess The variables were corrected to be interference-free. This significantly improved the welding results of welding system 1.

[0159] With the help of the calculated coupling factor K R K L The user of welding system 1 also obtains information about the degree of interference coupling between the welding circuits of welding system 1. In a feasible embodiment of the compensation method according to the invention, a calculated coupling factor is used to reduce or eliminate the welding current I supplied by another welding power source for welding the same workpiece 3 to the welding power source for welding workpiece 3. S Interference. On the other hand, the user of welding system 1 can calculate or determine the coupling factor K. R K L This optimizes the wiring arrangement of the welding system 1 itself, particularly the various welding circuits 2-i. The user can be informed of the inductive and / or ohmic coupling levels between the welding circuits 2-i via a display of the welding power source. The method according to the invention for determining interference coupling between the welding circuits 2-i of the welding system 1 is particularly suitable for welding systems 1 comprising two or more welding circuits 2-i or welding power sources 4-i.

Claims

1. A method for determining interference coupling between welding circuits in a welding system (1), the method comprising the steps of: - A predetermined current distribution (SP) is applied (S1) in the first welding circuit (2-1) of the welding system (1), wherein the current distribution (SP) applied in the first welding circuit (2-1) has one or more current pulses; - Detect (S2) the voltage and / or current processes thus induced in the second welding circuit (2-2) of the welding system (1); and - Based on the current distribution (SP) of the current applied in the first welding circuit (2-1) and the induced voltage and / or current processes detected in the second welding circuit (2-2), the interference coupling is determined (S3).

2. The method according to claim 1, in, The welding circuit of the welding system (1) is short-circuited to determine interference coupling between the welding circuits.

3. The method according to claim 1 or 2 above, in, Based on the current distribution (SP) applied in the first welding circuit (2-1) and the voltage and / or current processes detected in the second welding circuit (2-2), the ohmic portion of the coupling between the welding circuits of the welding system (1) is determined in at least one first measurement window (MF1), and the inductive portion of the coupling between the welding circuits of the welding system (1) is determined in at least one second measurement window (MF2).

4. The method according to claim 3, in, The first measurement window (MF1) is in the stage where the applied current level is constant in the current distribution (SP) applied in the first welding circuit (2-1).

5. The method according to claim 3, in, The second measurement window (MF2) is in the stage where the applied current level in the current distribution (SP) applied in the first welding circuit (2-1) rises during the rising edge of the current pulse or falls during the falling edge of the current pulse.

6. The method according to claim 3 above, in, Calculate the coupling factor, which represents the ohmic portion and / or the inductive portion coupled between the welding circuits of the welding system (1).

7. The method according to claim 6, in, The calculated ohmic coupling factor (K) represents the ohmic portion of the coupling between the welding circuits. R ), and the calculated inductance coupling factor (K) representing the inductance portion of the coupling between the first welding circuit (2-1) and the second welding circuit (2-2). L The data is stored in the welding power supply of the welding circuit of the welding system (1), or in the database.

8. The method according to claim 7, in, The calculated Ohmic coupling factor (K) R ) and the calculated inductive coupling factor (K L The output is given to the user via the user interface of the welding system (1).

9. The method according to claim 1, in, The voltage and / or current processes detected in the second welding circuit (2-2) are stored in the data memory of the second welding circuit (2-2).

10. The method according to claim 1, in, The current distribution (SP) applied in the first welding circuit (2-1) is stored in the data memory of the second welding circuit (2-2), or transmitted from the first welding circuit (2-1) to the second welding circuit (2-2) wirelessly or wiredly via a communication connection (KV).

11. The method according to claim 1, in, Initially, the welding circuits of the welding system (1) are synchronized to determine interference coupling between the welding circuits.

12. The method according to claim 6 above, in, The calculated and stored coupling factor is used to determine the compensation voltage (U) based on the current distribution (SP) of the current (I) applied in another welding circuit. Komp ).

13. The method according to claim 12, in, The measured voltage (U) is obtained from the voltage measuring unit of the welding power source located in the welding circuit. MESS Subtract the compensation voltage (U) from the original value. KOMP ), to determine the adjusted measurement voltage (U') MESS The adjusted measurement voltage is used to regulate the welding current generated by the welding power supply of the welding circuit.

14. A welding system (1) including a welding circuit for simultaneously welding one or more workpieces (3). in, The welding system (1) has a coupling determination unit that determines interference coupling between welding circuits by means of any one of claims 1 to 13.

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