Abstract: A power supply connectable to a source of AC line voltage for AC electric arc welding by an AC arc current across a welding gap between an electrode and a workpiece, the power supply comprises a high capacity transformer that converts said line voltage to an AC output voltage, and a rectifier that converts the AC output voltage to a DC voltage between a positive terminal and a common terminal at generally zero volts and a negative terminal and the common terminal. The power supply has a first switch that connects the positive terminal to the common terminal across the gap when a gate signal is applied to the first switch, a second switch for connecting the negative terminal to the common terminal across the gap when a gate signal is applied to the second switch and a pulse width modulator operated for generating pulses at a frequency of at least about 18 kHz.

Abstract: In a standard electric arc welder of the type having a main power supply with an off condition directing no current across an electrode and a workpiece and an on condition directing welding current between the electrode and the workpiece and through a choke, there is provided a secondary power supply with a switch closable to cause the secondary power supply to apply a given voltage across a series circuit including a high inductance inductor, the electrode and the workpiece. The sensed instantaneous current from the secondary power supply and the voltage between the electrode and the workpiece is multiplied and integrated to create a signal representing accumulated heat between the electrode and the workpiece. A comparator circuit has a first input for the time function signal, a second input for a fixed reference signal and an output for a switching signal when the time function signal equals and/or exceeds said reference signal.

Abstract: A short circuit arc welding system is disclosed. The control scheme uses a current command signal to drive the output current. The command signal is comprised of a long-term current command that sets the long-term current command level and a real-time or short-by-short current command. Arc voltage feedback is used to determine if the desired arc length is present and to adjust the long-term command. The short-by-short current command is derived from real-time arc current feedback and is used to control the burn-off rate by an instantaneous, or short-by-short, adjustment of the current command. A function of the time derivative of arc power, less the time derivative of arc current, is used to detect, in real time, when the short is about to clear. A stop algorithm is employed that monitors the arc on a short-by-short basis. When the process is ending a very low current level is provided to avoid forming a ball.

Abstract: An arc welding apparatus (10) for performing a waveform-controlled arc welding process includes an arc welding torch (14) that interacts with an associated weld. A power supply (12) applies a selected waveform-controlled power to the welding load via the arc welding torch (14) and a grounding cable over a process interval (Tweld). The power supply (12) includes a sampling circuit (34) for sampling instantaneous current and voltage values of the power during a snip portion (Tsnip) of the process interval (Tweld). A processor (40) is designed to (i) compute a true heat over the snip portion (Tsnip) of the process interval (Tweld), and (ii) extrapolate a true heat over the process interval (Tweld) based thereon.

Abstract: A system 11 for controlling an arc welding system 10 operating in a dip transfer mode is disclosed. The control system is operative to control the current output from a power source so as to apply a current pulse during the arcing phase of the welding system which is operative to form a molten droplet on the electrode of the welding torch 13 which is within a predetermined threshold size range, The control system 11 is then operative to clamp the current output from the power source 12 so that bridge rupturing occurs at relatively low current levels to thereby significantly reduce spatter during bridge rupturing.

Abstract: An electric arc welder with a variable AC voltage input of up to 600 VAC and a rectifier to provide a DC link, a driven high frequency boost stage with first and second leads connected to the DC link. The boost stage comprises an inductor, a first series output branch with a first primary winding connected to the first lead and a first capacitor connected to the second lead, a second series output branch with a second primary winding connected to the second lead and a second capacitor connected to the first lead and a high frequency operated switch between the leads and having an opened condition charging said capacitors by current through the primary windings in a first direction and discharging the inductor and a closed condition charging the inductor through the primary windings by current in a second direction and discharging the inductor to charge the capacitors. The switch is operated by a power factor control circuit at a frequency greater than about 18 kHz.

Abstract: A power circuit for a welding power supply includes a rectifier circuit and a control circuit. The rectifier circuit includes a plurality of switches (e.g., silicon-controlled rectifiers). The control circuit is configured to provide a first control signal to a first switch at a predetermined firing angle to provide welding power through the first switch. The control circuit is configured to provide a second control signal to a second switch to allow freewheeling current to flow through the second switch.

Abstract: A control system for an electric arc welder performing a welding process between an electrode and a workpiece, which system comprises: a high speed switching type power supply with a controller operated at a switching frequency of at least about 10 kHz with an input current control signal to adjust the output current of the power supply; a first sensor sensing the actual arc voltage; a second sensor sensing the actual arc current; a first circuit for creating a power signal representing the desired real time power level at progressive times during the welding process; a second circuit for creating a function of the sensed actual voltage and the sensed actual current; and a third circuit for adjusting the current control signal in accordance with the difference between the power signal and the function of the actual voltage and current, preferably arc power.

Abstract: The invention describes a method of controlling a welding unit (1) and a current source (2), in which various welding parameters, such as a welding current, a welding wire diameter, a welding method etc., for example, can be set by a user from an input and/or output device (22). The set welding parameters are applied to a control device (4). The welding unit (1) and the current source (2) are then activated by the control device (4) in accordance with the predetermined welding parameters. Prior to, during and/or after start-up of the welding process, the user can set a surface area or a cross section of a weld seam, in particular a fillet weld, from the input and/or output device (22), after which the control device (4) scans and/or retrieves and displays desired values for additional parameters needed to form the weld seam and/or for the welding procedure, stored in a memory device in particular.

Abstract: A method and apparatus for welding is disclosed. It includes a source of power and a controller. An output feedback circuit provides feedback to the controller. The controller includes a comparator that compares the fedback signal to a threshold and/or detects a short on the output. A standby/welding control is responsive to the comparator. Also, an arc end control may be provided that terminates the arc in response to detecting an increase in arc length.

Abstract: An electric arc welder operated to perform a short circuit process with a first waveform controlling a short condition followed by a second waveform controlling an arc condition, wherein the welder includes a comparator to create an arc signal when the short condition terminates and a controller shifting the welder from control by the first waveform to control by the second waveform in response to creation of the arc signal.

Abstract: A method of determining the impedance, inductance, and resistance of the network connecting an electrical power supply to an electric arc welding station including an electrode and a workpiece, wherein the method comprises: shorting the electrode to the workpiece; creating at least one waveform including a first state operating the power supply at constant current of a selected value and a second state operating the power supply at a low value of current or open circuit voltage whereby the current decays from the selected value along a decay path indicative of di/dt; obtaining the average current Iavg and average resistance Ravg during the first state; selecting a portion of the decay path; sampling the instantaneous current for a number of times on the path during the second state to read the rate of the decay; and, using the average current and the average resistance with the rate of decay to obtain the inductance of the network.

Abstract: A short circuit arc welding system is disclosed. The control scheme uses a current command signal to drive the output current. The command signal is comprised of a long-term current command that sets the long-term current command level and a real-time or short-by-short current command. Arc voltage feedback is used to determine if the desired arc length is present and to adjust the long-term command. The short-by-short current command is derived from real-time arc current feedback and is used to control the burn-off rate by an instantaneous, or short-by-short, adjustment of the current command. A function of the time derivative of arc power, less the time derivative of arc current, is used to detect, in real time, when the short is about to clear. A stop algorithm is employed that monitors the arc on a short-by-short basis. When the process is ending a very low current level is provided to avoid forming a ball.

Abstract: A DC TIG welder operable at a set low current level under about 5 amperes in a welding circuit including an electrode separated from a workpiece by a gap, the welder having an output welding current adjustable above the low current and driven by a constant current power supply with a first rectifier having an output current controlled by the firing phase of SCRs in an SCR network, a second rectifier settable at the low current and a sensor for sensing arc voltage. The welder further comprises: a circuit to deactivate the SCRs when the output welding current is equal to or less than the set low current and an arc starting device to cause the first rectifier to output a high pulse by operation of the SCRs of the network.

Abstract: The invention comprises a method and an arrangement for pulsed gas metal-arc welding with an electrode fed to the welding site continuously at a given rate, the fusion conditions being adapted in such a manner that the material transfer from the electrode (7) to the workpiece (8) takes place essentially without short-circuiting drops by the welding current being periodically increased to a pulse current of such size and duration that the current density in the electrode causes sufficient electromagnetic forces in order to separate one drop for each pulse, and where the arc length is stabilized by regulating the power supply for the arc by means of a regulator mainly on the basis of a measured arc voltage, characterized in that short-circuiting of the arc is detected as arc-voltage decreases and/or current increases, and in that the fusion power supplied is increased by the arc-length regulator being given an additional increase for each short-circuit detected.

Abstract: A power supply connectable to a source of AC line voltage for AC electric arc welding by an AC arc current across a welding gap between an electrode and a workpiece, the power supply comprises a high capacity transformer that converts said line voltage to an AC output voltage, and a rectifier that converts the AC output voltage to a DC voltage between a positive terminal and a common terminal at generally zero volts and a negative terminal and the common terminal. The power supply has a first switch that connects the positive terminal to the common terminal across the gap when a gate signal is applied to the first switch, a second switch for connecting the negative terminal to the common terminal across the gap when a gate signal is applied to the second switch and a pulse width modulator operated for generating pulses at a frequency of at least about 18 kHz.

Abstract: In a method and an apparatus for controlling AC pulse arc welding executed by supplying a welding current flowing between a welding wire and an object to be welded with feeding the welding wire at a feeding speed corresponding to a predetermined feeding speed setting signal, a one-period process for supplying the welding current is repeatedly executed. The one-period process includes a first process during a peak time interval, a second process during a negative electrode time interval, and a third process during a base time interval. The one-period process further includes a fourth process during a switching current interval, inserted between the peak time interval and the negative electrode time interval, for supplying a welding current having a switching current for stopping growth of droplet which is smaller than a threshold current with a positive electrode polarity.

Abstract: A method and apparatus for providing welding power includes controlling a phase controlled power circuit to provide a reduced OCV output. Preferably, the output is controlled in response to feedback, such as current being less than or greater than a threshold.

Abstract: A method and apparatus for providing welding power includes two power sources (first and second), each having an output. A linking circuit selectively connects the power sources in one of an independent mode (such that each is connected to a separate welding output whereby the first welding output is independent of the second welding output) or a combined mode (such that the power sources are connected in parallel and connected to one welding output whereby the outputs of the first power source and second power source are combined). A controller includes a mode selector to allow the user to select between the independent mode and the combined mode. Also, the controller includes a master output magnitude selector, which is a single selector, that controls the magnitude of the output of both power sources when the user has selected the combined mode. The power sources can be operated in a CV or CC mode when independent, or a CC mode when combined.

Abstract: A method and apparatus for welding with an engine driven inverter power supply includes generating an ac output with an engine and generator. The output is rectified and inverted to provide an ac inverter output. The engine is controlled using feedback indicative of a welding output operating parameter. The feedback may also be taken from the inverter or generator, and the generator may be controlled instead of or in addition to the engine. Engine parameters that may be controlled include engine speed, selecting between an idle speed and a run speed, a throttle position, a fuel pump, an injection timer, a fuel to air ratio, fuel consumption and ignition timing. Another aspect of the invention is having the feedback be responsive to one or more of the welding current, welding voltage, welding power, or functions thereof. The feedback may be responsive to the current, voltage, power, ripple and functions thereof.

Abstract: A method and apparatus for providing submerged arc welding power is disclosed. The power supply is AC/DC, and may be controlled in either a CV or a CC mode. The power supply includes a cycloconverter that provides a single phase output and receives a three phase input. A controller includes a PI current regulator for operation in the CC mode. The controller also includes a PI voltage regulator. When the CV mode is selected, the voltage and current regulators are cascaded such that the output of the voltage regulator is the set point input to the current regulator.

Abstract: A method of generating a real time control signal for use in an electric arc welding process having welding voltage and welding current, said method comprising: measuring the welding voltage and welding current at a first time, momentarily changing either the welding voltage or welding current by less than about 10%, then measuring the welding voltage and the welding current after the change at a second time, determining the welding voltage difference between the first time and the second time, determining the welding current difference between the first time and the second time, producing a derivative value representing the desired control signal by dividing the welding voltage difference between the first and second times by the welding current difference between the first and second times and generating the control signal by the derivative value.