US3896287A - Direct current arc power supply - Google Patents

Direct current arc power supply Download PDF

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Publication number
US3896287A
US3896287A US378265A US37826573A US3896287A US 3896287 A US3896287 A US 3896287A US 378265 A US378265 A US 378265A US 37826573 A US37826573 A US 37826573A US 3896287 A US3896287 A US 3896287A
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United States
Prior art keywords
current
feedback signal
signal
voltage
adjustable
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Expired - Lifetime
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US378265A
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English (en)
Inventor
George E Cook
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ADVANCED ROBOTICS Corp
Air Products and Chemicals Inc
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Air Products and Chemicals Inc
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Application filed by Air Products and Chemicals Inc filed Critical Air Products and Chemicals Inc
Priority to US378265A priority Critical patent/US3896287A/en
Priority to SE7408316A priority patent/SE412715B/sv
Priority to CA203,763A priority patent/CA1003506A/en
Priority to GB2954574A priority patent/GB1468198A/en
Priority to FR7423568A priority patent/FR2236601B3/fr
Priority to CH932574A priority patent/CH593755A5/xx
Priority to JP49078644A priority patent/JPS5039249A/ja
Priority to BR5650/74A priority patent/BR7405650D0/pt
Priority to NL7409316A priority patent/NL7409316A/xx
Priority to AU71045/74A priority patent/AU488813B2/en
Priority to BE2053744A priority patent/BE817523A/xx
Priority to DE2433275A priority patent/DE2433275C3/de
Priority to IT83377/74A priority patent/IT1018464B/it
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Publication of US3896287A publication Critical patent/US3896287A/en
Assigned to ADVANCED ROBOTICS CORPORATION reassignment ADVANCED ROBOTICS CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: ARC SYSTEMS,INC.
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/32—Plasma torches using an arc
    • H05H1/34—Details, e.g. electrodes, nozzles
    • H05H1/36—Circuit arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/06—Arrangements or circuits for starting the arc, e.g. by generating ignition voltage, or for stabilising the arc
    • B23K9/073—Stabilising the arc
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
    • B23K9/1006—Power supply
    • B23K9/1043—Power supply characterised by the electric circuit
    • B23K9/1056—Power supply characterised by the electric circuit by using digital means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/145—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
    • H02M7/155—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
    • H02M7/1555—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with control circuit
    • H02M7/1557—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only with control circuit with automatic control of the output voltage or current

Definitions

  • a feedback control sys- [22] filed July 1973 tem includes first and second cascaded operational [2-1;] A l N 378,265 amplifiers.
  • the first amplifier sums (l) a reference set point signal, (2) an adjustable voltage feedback signal and (3) an adjustable current feedback signal.
  • the 219/131 219/] first amplifier provides low pass filtering to smooth the 131 R otherwise high ripple content of the two feedback sigre 0 care 219/135 321/1 nals.
  • the second amplifier provides both integral and proportional control and drives a firing circuit.
  • the current [56] References cued and voltagefeedback signals may be adjusted to pro- UNITED STATES PATENTS vide infinite and continuous control of the voltampere 3,530,359 9/1970 Grist 219/135 X characteristic of the power supply between a constant 5 99 70 Steams et l- 219/135 X current characteristic and a constant potential charac- 3-68818O 3/1972 Chlasson a] 219/135 x teristic.
  • An adjustable start circuit provides control of the average output voltage, and hence the initial are energy, at the start of operation to more easily establish the arc.
  • This invention relates to the field of art of direct current are power supplies having feedback control systems.
  • Prior Art Direct current power supplies are known in which an arc is established and maintained between apair of electrodes.
  • the incoming line voltage is reduced in potential by a transformer, the output of which is full wave rectified for establishing a desired direct current voltage and current output.
  • Such an arc welding supply is disclosed in US. Pat. No. 3,549,978 in which a polyphase transformer-rectifier system includes silicon controlled rectifiers and has both current and voltage feedback control. This feedback control is effective to establish the desired phasing or firing" of the silicon controlled rectifiers.
  • the feedback control system comprises a pair of summing amplifiers, the first of which sums (l) a reference set voltage and (2) the current feedback.
  • the second amplifier sums (1) an output of the first amplifier and (2) the voltage feedback.
  • a separate slope adjustment circuit is provided in the current feedback to establish substantially zero slope even though the resistance in the output line tends to establish a drooping characteristic.
  • Such prior power supplies have left much to be desired in that the range of slope control in the constant potential mode is limited for stable operation. As a result, such prior supplies have been limited primarily to theshort are or spray transfer mode of welding where either a constant potential or a slightly drooping volt-ampere characteristic is desired.
  • a direct current are power supply for controlling the volt-ampere characteristic of direct current applied to establish and maintain an are between a pair of electrodes.
  • a set reference signal is produced related to a desired value of direct current.
  • the are current is sensed to provide an adjustable current feedback signal.
  • the voltage across the electrodes is sensed to provide an adjustable voltage feedback signal.
  • a feedback control system sums the set reference signal, the adjustable current feedback signal and the adjustable voltage feedback signal and applies a resultant control signal to a power circuit to control the volt-ampere slope characteristic.
  • There is simultaneously adjusted both the adjustable current sensing means and the adjustable voltage sensing means to provide infiniteand continuous control of the volt-ampere characteristic of the power supply between a constant current characteristic and a constant potential characteristic.
  • the simultaneous adjustment is provided by a single slope adjustment control in the form of a mechanicalgang between a current slope potentiometer and a voltage slope po-' tentiometer. These two potentiometers are interconnected so that with the single slope adjustment control set to one extreme, the current feedback signal is maximum and the voltage feedback signal is zero thereby providing a true constant current volt-ampere characteristic. With the single slope adjustment control set to the other extreme, the current feedback signal is zero and the voltagefeedback signal ismaximum, thereby providing a true constant potential volt-ampere characteristic.
  • This single slope adjustment control may be adjusted continuously between the .two extremes to yield an infinitely adjustable volt-ampere slope characteristic. r I
  • the are power supply may be used in applications without the adverse stability characteristics inherent in the prior art supplies.
  • the invention may be used not only in the short are or spray transfer modes of welding (Gas Metal Arc Welding) but may be used equally well for automatic or manual Gas Tungsten Arc Welding and Shielded Metal Arc Weldingfl'he are power supply may use solid state construction with high gain feedback operational amplifiers to provide a highly reliable and long life system in addition to compensating for ambient temperature conditions in the circuitry of the feedback control system.
  • semiconductor devices increase in temperature, they tend to decrease in resistance in direct opposition to the increase in resistance associated with increase in temperature of resistors in the circuit.
  • highly desirable continuously adjustable slope and setpoint control with a stable output which is essentially independent of load, line and temperature conditions.
  • FIG. 1 there is shown an are power supply system 10 in which a three phase power source 11 supplies a polyphase welding transformer 12.
  • Transformer 12 provides an alternating current input to a full wave polyphase rectifier assembly 14.
  • Rectifier 14 has a pair of output leads 15 and 16 with output lead or load line 16 indicated as the negative lead and output lead or load line 15 indicated as the positive lead.
  • output negative lead 16 is connected to an electrode 20 while output positive lead 15 is connected by way of a shunt 22 to a work member 23.
  • supply system 10 When supply system 10 is energized, an are 26 is established and maintained between electrode 20 and work member 23.
  • leads l5 and 16 are 'useful for both the manual and automatic modes of the Gas Tungsten Arc Welding (GTAW or TIG) process for certain modes of the Shielded Metal Arc Welding process (dependent. on the particular type of shielded electrode 20 used).
  • GTAW or TIG Gas Tungsten Arc Welding
  • the volt-ampere Characteristic of system 10 is preset so that a desired straight line characteristic 30 is substantially tangent to an ideal constant power characteristic (K) 31.
  • Voltage V is the voltage across arc 26 taken between leads l5 and 16 while current I is the actual current through arc 26. The tangency is provided at a desired nominal operating point 33.
  • Ideal constant power characteristic 31 is a known characteristic in the Gas Tungsten Arc Welding process.
  • the volt-ampere characteristic of system 10 is preset normally to either a true constant potential characteristic or a slightly drooping (negative slope) characteristic.
  • the volt-ampere characteristic of system 10 is preset normally to a higher magnitude negative slope characteristic than that in the spray transfer mode.
  • the Shielded Metal Arc Welding mode the volt-ampere characteristic is set the same as in the manual mode of the Gas Tungsten Arc Welding process.
  • a reference set point voltage input 40 (set in a manner to be described) is applied to one input 42a of a summing filter amplifier 42.
  • a second input 42c of amplifier 42 is connected to a current feedback unit 45 while a third input 42b to amplifier 42 is taken from a voltage feedback unit 46.
  • amplifier 42 is effective to sum the set reference signal, an adjustable current feedback signal and an adjustable voltage feedback signal.
  • Current feedback unit 45 obtains its current input from a current sensor or shunt 22 which provides a signal proportional to the current through lead (arc current I).
  • Load resistors 17 are connected between leads l5 and 16 and voltage feedback unit 46 is connected across load resistors 17 to provide a signal proportional to the voltage across arc 26.
  • Units 45 and 46 comprise potentiometers which are mechanically ganged by gang 47. The potentiometers are ganged so that with a setting at one extreme (as for example, clockwise) the voltage feedback signal at voltage feedback conductor 44 is of zero value and the current feedback signal at current feedback conductor 43 is of maximum magnitude. Accordingly, at the output 50 of amplifier 42 there is produced a voltage signal proportional to the setting of reference 40 which at that time establishes the desired set point of current.
  • the output of amplifier 42 provides a voltage signal proportional to the setting of reference 40 which establishes the desired set point of voltage.
  • output 50 produces modified proportional set point signals related to the slope characteristic established by the current and voltage feedback signals.
  • One of the slope characteristics is shown in FIG. 2A as characteristic 30 while another is shown as characteristic 37.
  • Amplifier 42 also provides low pass filtering characteristic which is effective to smooth the otherwise high ripple content of the current feedback applied to input 42c and the voltage feedback applied to input42b.
  • Output 50 of amplifier 42 is connected to an input of amplifier of 52 which provides both integral plus proportional control of the feedback for system 10,
  • the output of amplifier 52 is effective to control the firing networks of firing unit 55.
  • Firing unit 55 is adapted to provide properly timed and spaced firing pulses to a bank of triggered silicon controlled rectifiers in rectifier'14. With this proper phasing of rectifier 14, there is established and maintained the desired voltage and current characteristics at output leads l5 and 16 and therefore to arc 26.
  • a start circuit 53 is effective to provide controlled arc energy at the start of operation to more easily establish arc 26.
  • a relay is energized thereby removing the start weld setting so that the weld current assumes its normal desired value as established by reference 40.
  • current feedback unit 45 comprises a separate potentiometric slope adjustment connectedbetween shunt 22 and input 420 while voltage feedback unit 46 comprises a separate potentiometric slopeadjustment connected between load resistors 17 and input 42b.
  • the current slope potentiometer is mechanically ganged to the voltage slope potentiometer.
  • the current feedback signal is maxirr'iurnand the voltage feedback signal is zero, thereby providing a true constant current volt-ampere characteristic.
  • the current feedback signal at conductor 43 is at a maximum and the current through arc 26 is maintained substantially constant at a value determined by the setting of reference.
  • the current I through are 26 may be amps at one setting, 500 amps at another setting, etc.
  • Each constant current characteristic varies between a voltage value approaching zero volts (as for example, 5 volts) to the maximum voltage of supply system 10.
  • the single slope adjustment control (gang 47) is set to the other extreme, the current feedback signal zero and the voltage feedback signal is maximum, thereby providing a true constant potential volt-ampere characteristic.
  • the voltage feedback at conductor 44 is maximum and the voltage across are 26 is maintained substantially constant at a voltage value determined by the setting of reference 40.
  • the voltage across are 26 may be 20 volts at one setting, 40 volts at another setting, etc. with current varying from a minimum to a maximum value.
  • the single slope adjustment control (gang 47) may I be adjusted continuously between the two extremes to yield an infinitely adjustable volt-ampere slope characteristic.
  • transformer 12 comprises a three phase delta primary 60 and a six phase star secondary 62.
  • the windings of primary 60 andsecondary 62 are suitably coupled on a common core (not shown) to provide a constant potential transformer.
  • Power source 1 1 is coupled to primary 60.
  • the common 64 or star point of secondary 62 is connected by way of lead or load line through current sensing shunt 22 to work member 23.
  • the outer end of each phase winding of secondary 62 is connected through respective silicon controlled rectifiers (SCR) 70a-b, 7l a'-b, 72a-b and then through a smoothing and stabilizing reactor 67 and lead or load line 16 to electrode 20.
  • Reactor 67 is provided with taps so that different values may be selected for different rriodes of welding.
  • phase 62a is connected to a pair of SCRs 7 0a-b and then through reactor 67 to line 16.
  • the adjacent phase 62b is connected to a similar 'pairof SCRs 7lab and the final phase 620 is connected to a final pair of SCRs 72a-b.
  • Each pair of SCRs 70a-b, 71a-b, and 72a-b is connected to a firing unit 55 for simultaneous pulsing with the three pairs being pulsed in proper sequence. In this manner, the portion of the half-wave of each winding applied across leads 15-16 is controlled by the phased firing of the respective SCRs.
  • a background supply comprising auxiliary secondary windings 66a-c in the main power transformer 60. Windings 66a-c are .connected in three phaseidelta with the output thereof .coupled to a background rectifier 69. Rectifier 69 may be connected as a three phase bridge rectifier. The output of the rectifier 69 is coupled through a switch 69a to leads 15 and 16. This circuit operates to help establish a more stable arc by smoothing the ripple produced by the arc.
  • Firing unit 55 may be any one of the firing units well known in the art toprovide the required phase control and firing of SCRs.
  • unit 55 may be a firing unit Part No. R6l3F372 manufactured by Firing Circuit, Inc., Norwalk, Conn.
  • Firing unit 55 is actuated by an input conductor 74 which is coupled by way of a gain control potentiometer 75 to output 77 of amplifier 52.
  • the signal at conductor 74 determines the particular time in each half cycle at which a firing pulse is applied to a particular SCR and thereby determine the particular time in the phase that SCR conducts the output applied to it from secondary 62. Since power source 11 is also applied to firing unit 55, this power input is synchronizedwith the control voltage applied to an SCR.
  • the firing of the SCR is modified by the input signal at conductor 74 which reflects the current feedback produced by unit 45 through summation amplifier 42 thereby to establish a desired voltage and current slope characteristic.
  • Shunt 22 comprises a millivolt shunt connected in series with lead 15.
  • the upper end 22b of shunt 22 is coupled by way of common lead 80 to the junction of fixed contacts of current and voltage feedback potentiometers 82, 83 respectively. Common is the common for the entire electronic feedback circuit.
  • the lower end 22a of shunt 22 is coupled by way of conductor 84 to the other fixed contact of current potentiometer 82. In this manner, potentiometer 82 is coupled across shunt 22 and the current feedback signal is taken from moveable arm 82a of potentiometer 82 with respect to common 80. That current feedback signal is applied to input 420 of summing filter amplifier 42.
  • input 420 is coupled to an input circuit 85 comprising resistors 80a-c in series and capacitors 97ab.
  • One end of the series resistance circuit is connected to input 420 and the other end is connected to a summing junction 92 of an operational amplifier 100 which comprises the amplifying device of summing filter amplifier 42.
  • the values of these resistance and capacitance feedback components are selected in conjunction with the values of resistors a-c and capacitors 97a-b to provide adequate filtering of the current feedback millivolt signal.
  • These components are further selected to provide proper voltage gain to make the current feedback millivolt signal compatible with the reference set point voltage applied to input 42a and the voltage feedback signal applied to input 42b.
  • the voltage levels applied to inputs 42a -b may for example each be adjusted to approximately a 10 volt maximum. level. i
  • a series circuit of a potentiometer 17b and a fixed resistor 17a (load resistors 17) is connected between the other fixed contact of potentiometer 83 and load line 16.
  • the potential between load lines 15 and 16 is developed across the series circuit combination of resistors l7a-b and 83 with the voltage feedback signal taken from arm 83a of potentiometer 83 with respect to common.
  • the voltage feedback signal is adjusted to a level compatible with the set point reference voltage40:
  • the voltage feedback signal is applied by way of conductor 44 to input 42b.
  • input 42b is connected to input circuit 86 comprising resistors 9311 -10 in series circuit coupled to junction 92 and capacitors 98ab.
  • the values of the components of this resistance-capacitance network are selected in conjunction with the feedback resistance-capacitance network 102 to provide adequate, unity gain filtering of the voltage feedback signal.
  • reference circuit 40 For the reference set point voltage, reference circuit 40 comprises a potentiometer 95 having its arm connected to input 42a. One fixed contact of the potentiometer is connected to common while the other fixed contact is connected through a potentiometer 96 to a positive supply. Input 42a is coupled within amplifier 42 to an input circuit 87 comprising resistors 94a-c in series circuit and capacitors 99a-b. The values of these components are selected in conjunction with the values of the components of the resistance-capacitance feedback network 102 to provide a transfer function for the reference input which is compatible with the current feedback to input 420 and the voltage feedback to input 42b.
  • Input circuits 85-87 remote from inputs 42c, 42b and 42a, respectively are summed at junction 92 which is coupled to the negative input of operational amplifier 100.
  • Input circuits 85-87 and feedback network 102 effectively define a Butterworth filter network.
  • An additional input to junction 92 may be traced by way of a resistor 116 and then to an arm of a potentiometer 115.
  • One fixed contact of potentiometer 115 is connected by way of a resistor 114 to a positive supply and the other fixed contact is connected to common.
  • Potentiometer 115 and resistor 114 form an adjustable voltage divider network used to calibrate the low end of the reference potentiometer readout in amperes when the slope is adjusted to the constant current mode.
  • Potentiometer 96 previously described, is used to calibrate the high end of reference potentiometer 95 readout in amperes when the slope is adjusted to the constant current mode.
  • the arms 82a and 83a are ganged together by gang 47 to provide a single slope adjustment control as previously described.
  • gang 47 With gang 47 at" its extreme right position (corresponding to the extreme clockwise position) it will be seen that arm 82a is at its furthest position from common while arm 83a is at its closest position. Accordingly, the current feedback is at a maximum and the voltage feedback is at a minimum.
  • arm 82a With gang 47 in its extreme lefthand position (corresponding to the extreme counterclockwise position) arm 82a is at its closest position to common while arm 83a is at its furthest position. Accordingly, the current feedback is zero and the voltage feedback is maximum.
  • the output of operational amplifier 100 is applied by way of a potentiometer 120 and a resistor 121 to the negative input of an operational amplifier 125; the positive input of which is connected by way of a resistor 123 to common.
  • the output of amplifier 125 is connected by way of an integrator capacitor 130 and a resistor 131 to the negative input.
  • operational amplifier 125 operates as an augmented integrator, or integral plus proportional amplifier.
  • capacitor 130 charges in such a direction as to drive the output of amplifier 125 and hence the firing circuit 55 to that level necessary to reduce the error signal to zero.
  • Potentiometer 120 may be adjusted to set the closed loop gain of the feedback circuit.
  • Start circuit 53 is provided to assist in the start of sup- 1 ply system 10. It will be understood that in both manual and automatic welding that it is desired to have higher weld currents at the start of operation in order to more easily establish are 26. However, once the arc has been established, it is necessary that the weld current be decreased to its normal desired value as established by reference 40.
  • start up relay 142 is deenergiz ed and the normally closed contact 142a is effective to apply the start weld level setting of potentiometer 144 to the input of amplifier 125.
  • Thislevel setting is applied to firing unit 55 for the higher value start up current.
  • the weld current I increases sufficiently to produce a potential at input a of amplifier 135 greater than the setting of voltage divider 136 than transistor switches thereby energizing relay 142 and opening the contact 142a. With contact 142a open, the start weld setting is removed and amplifier-52 operates normally.
  • referencesetpoint means to produce a set reference signal related toa desired value of said direct current, adjustable means connected to said lead means for sensing said are current and providing an adjustable current feedback signal,
  • adjustable means connected to said lead means for sensing the voltage across said electrodes and providing an adjustable voltage feedback signal
  • feedback control means coupled to said power means for summing said set reference signal, said adjustable current feedback signal and said adjustable voltage feedback signal for applying a control signal to said power means to control said voltampere characteristic
  • adjustable current sensing means comprises a current sensor coupled to said lead meansand voltage potentiometric slope adjustment means coupled to said current sensor for providing said adjustable current feedback signal proportional to the current flow through said lead means
  • adjustable voltage sensing means comprises load resistor means coupled to said lead means and voltage potentiometric slope adjustment means coupled to said load resistor means for providing said adjustable voltage feedback signal proportional to said voltage across said electrodes.
  • the arc power supply of claim 3 in which'said simultaneously adjusting means comprises rrieans for ganging said current and voltage potentiometric means so that 1) at one extreme setting of said ganging means the current feedback signal is maximum and the voltage feedback signal is of zero value to produce a control signal proportional tosaid set reference-signal for establishing a desired setpoint of current, and (2) at another extreme setting of said ganging'means and voltage feedback signal is maximum and the current feedback signal is of zero value to provide-a control signal proportional to the set reference signal for establishing a desired setpoint of voltage; with intermediate settings of said ganging means producing proportional control signals related to the slope characteristics established by the current and voltage feedback signals.
  • said feedback control means includes first amplifier means for summing said set reference, said adjustable current and adjustable voltage feedback signals and for providing a low pass filtering characteristic for Smoothing the high ripple content of said feedback signals.
  • said feedback control means includes second amplifier means connected to the output of said first amplifier means for providing integral plus proportional control of the first amplifier output and for applying the resultant signal as said control signal to said power means.
  • said first amplifier means comprises first, second, and third input circuits connected respectively to said reference setpoint means, said adjustable current sensing means and said adjustable voltage sensing means, a first operational amplifier having an input connected to a common junction coupling said first, second, and third filter input circuits, a resistance-capacitance network providing feedback for said first operational amplifier, and said first, second, and third input citcuits and said feedback network forming a Butterworth network.
  • said first input circuit is a resistance-capacitance circuit having values selected in conjunction with the values of said resistance-capacitance feedback circuit provide a transfer function of the said set reference signal which is compatible with the current feedback signal and said voltage feedback signal.
  • start means comprises start reference means for establishing a start reference signal, means connected to said adjustable current sensing means for comparing a nonadjustable current feedback signal with said start reference signal for (l) applying at the start of operation said start level setting and (2) returning said control signal to its normal value when the arc current increases sufficiently to increase the nonadjustable current feedback signal to a predetermined value with respect to said start reference signal so that said direct current decreases to its desired value established by said set reference signal.
  • said comparing means comprises a third operational ampli-' bomb and a relay connected to an output of said third operational amplifier, said relay having normally closed contacts connected in circuit with said feedback control means for applying said start level setting when said contacts are closed and for removing said start level setting when said contacts are opened upon actuation of said relay by said third operational amplifier.
  • reference setpoint means to produce a set reference signal related to a desired value of said direct current
  • feedback control means coupled to said power means for summing said set reference signal, said current feedback signal and said voltage feedback signal for applying a control signal to said power means to control the volt-ampere characteristic of said direct current
  • start reference means to produce a start reference signal
  • start means for comparing said current feedback signal with said start reference signal for varying said control signal upon startup to produce saiddirect current of value higher than said desired value which value decreases to said desired value when said current feedback signal increases to a predetermined value with respect to said start reference signal.
  • start means includes an operational amplifier having one input coupled to said current sensing means.
  • relay means connected to an output of said operational amplifier and having a normally closed relay contact.
  • start level setting means connected to said normally closed relay contact and to said feedback control means for varying said control signal by a start level setting until said current feedback signal increases to said predetermined value at which time said relay is actuated.
  • said feedback control means includes an operational amplifier having an integrator capacitor connected in a feedback loop therewith and providing at an output said control signal, said start level setting means coupled in another feedback loop whereby upon startup a start level setting is applied to the input of said operational amplifier until said current feedback signal increases to said predetermined value.
  • a method of controlling the volt-ampere charac- 12 ing an adjustable voltage feedback signal related to the value of the electrode voltage, summing the set reference signal, the adjustable current feedback signal and the adjustable voltage feedback signal and controlling the volt-ampere characteristic as a function of these signals, and simultaneously varying both the adjustable current feedback signal and the adjustable voltage feedback signal to provide an infinite and continuous control of the volt-ampere slope characteristic of the direct current between and including a con-. stant current mode and a constant potential mode.
  • the simultaneously varying step includes simultaneously varying the signals so that (l) at one extreme the adjustable current feedback signal is maximum and the adjustable voltage feedback signal is zero thereby providing a constant current volt-ampere characteristic and (2) at another extreme the adjustable current feedback signal is zero and the adjustable voltage feedback signal is maximum thereby providing a constant potential volta'mpere characteristic.
  • the summing step includes providing a low pass filtering characteristic for smoothing the high ripple content of said adjustable current and voltage feedback signals and then providing integral plus proportional control.
  • the summing step includes varying the controlling of the volt-ampere characteristic by a start level setting at the start of oper-v ation to provide the direct current of value higher than said desired value established by said set reference signal.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Arc Welding Control (AREA)
US378265A 1973-07-11 1973-07-11 Direct current arc power supply Expired - Lifetime US3896287A (en)

Priority Applications (13)

Application Number Priority Date Filing Date Title
US378265A US3896287A (en) 1973-07-11 1973-07-11 Direct current arc power supply
SE7408316A SE412715B (sv) 1973-07-11 1974-06-25 Forfarande och anordning for att styra voltamperekarakteristikan hos en likstrom
CA203,763A CA1003506A (en) 1973-07-11 1974-07-02 Direct current arc power supply
GB2954574A GB1468198A (en) 1973-07-11 1974-07-03 Arc power supplies
FR7423568A FR2236601B3 (sv) 1973-07-11 1974-07-05
CH932574A CH593755A5 (sv) 1973-07-11 1974-07-08
JP49078644A JPS5039249A (sv) 1973-07-11 1974-07-09
BR5650/74A BR7405650D0 (pt) 1973-07-11 1974-07-09 Fonte de energia de arco de corrente continua e processo de controle das caracteristicas de volt-ampere da corrente continua aplicada
NL7409316A NL7409316A (nl) 1973-07-11 1974-07-10 Voeding voor gelijkstroomboog.
AU71045/74A AU488813B2 (en) 1973-07-11 1974-07-10 Direct current arc power supply
BE2053744A BE817523A (fr) 1973-07-11 1974-07-11 Alimentation en courant continu pour soudure a l'arc
DE2433275A DE2433275C3 (de) 1973-07-11 1974-07-11 Schaltanordnung für eine Stromquelle zum Gleichstrom-Lichtbogen-Schweißen
IT83377/74A IT1018464B (it) 1973-07-11 1974-07-11 Aroc alimentato a corrente conti nua

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US378265A US3896287A (en) 1973-07-11 1973-07-11 Direct current arc power supply

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US3896287A true US3896287A (en) 1975-07-22

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US378265A Expired - Lifetime US3896287A (en) 1973-07-11 1973-07-11 Direct current arc power supply

Country Status (12)

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US (1) US3896287A (sv)
JP (1) JPS5039249A (sv)
BE (1) BE817523A (sv)
BR (1) BR7405650D0 (sv)
CA (1) CA1003506A (sv)
CH (1) CH593755A5 (sv)
DE (1) DE2433275C3 (sv)
FR (1) FR2236601B3 (sv)
GB (1) GB1468198A (sv)
IT (1) IT1018464B (sv)
NL (1) NL7409316A (sv)
SE (1) SE412715B (sv)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3992659A (en) * 1974-07-19 1976-11-16 Allmanna Svenska Elektriska Aktiebolaget High voltage direct current transmission
US4109130A (en) * 1971-11-30 1978-08-22 Matsushita Electric Industrial Co., Ltd. Electric welder output control device
US4162379A (en) * 1977-02-25 1979-07-24 The Perkin-Elmer Corporation Apparatus for deriving a feedback control signal in a thermal system
US4241285A (en) * 1978-06-29 1980-12-23 Erico Products, Inc. Power supply for SMAW welding and stud welding
US4264858A (en) * 1979-05-29 1981-04-28 General Electric Company Means for regulating resistance current of complex load
US4287557A (en) * 1979-12-17 1981-09-01 General Electric Company Inverter with improved regulation
US4412277A (en) * 1982-09-03 1983-10-25 Rockwell International Corporation AC-DC Converter having an improved power factor
US4517439A (en) * 1984-05-07 1985-05-14 Colley Bruce H AC-DC welding power supply
US5157236A (en) * 1990-03-29 1992-10-20 Miller Electric Mfg. Co. Adaptive pulse mode gas metal arc welding control
US5482734A (en) * 1994-05-20 1996-01-09 The Miller Group, Ltd. Method and apparatus for controlling an electric arc spraying process
US5528010A (en) * 1994-05-20 1996-06-18 The Miller Group, Ltd. Method and apparatus for initiating electric arc spraying
US5665256A (en) * 1995-12-19 1997-09-09 The Esab Group, Inc. Cutting or welding system having phase loss detector and method of detecting phase loss for same
US6335511B1 (en) 1999-04-12 2002-01-01 Tri Tool Inc. Control method and apparatus for an arc welding system
US20060060574A1 (en) * 2003-09-08 2006-03-23 Lincoln Global, Inc. Electric arc welder and method for controlling the welding process of the welder

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1492311A (en) * 1975-03-06 1977-11-16 Atomic Energy Authority Uk Electric arc-welding processes and apparatus therefor
DE3338243A1 (de) * 1983-10-21 1985-05-15 Messer Griesheim Gmbh, 6000 Frankfurt Einrichtung zum lichtbogenschweissen
EP0528913A4 (en) * 1990-05-15 1993-07-28 The University Of Sydney A dc switched arc torch power supply
AU651114B2 (en) * 1990-05-15 1994-07-14 Electricity Commission Of New South Wales, The A DC switched arc torch power supply
JPH05508050A (ja) * 1990-06-15 1993-11-11 ザ　ユニヴァーシティ　オヴ　シドニー 直流アークトーチ電源
AU651120B2 (en) * 1990-06-15 1994-07-14 Electricity Commission Of New South Wales, The A DC arc torch power supply

Citations (3)

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US3530359A (en) * 1968-09-20 1970-09-22 Miller Electric Mfg Adjustable arc welding power supply system
US3549979A (en) * 1969-04-25 1970-12-22 Chemetron Corp Arc power supply with current level control
US3688180A (en) * 1971-01-14 1972-08-29 Hobart Brothers Co Welding apparatus

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Publication number Priority date Publication date Assignee Title
US3371242A (en) * 1964-04-07 1968-02-27 Harnischfeger Corp Arc power supply using solid state control devices for phase shifting
CS165445B1 (sv) * 1968-08-01 1975-12-22

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Publication number Priority date Publication date Assignee Title
US3530359A (en) * 1968-09-20 1970-09-22 Miller Electric Mfg Adjustable arc welding power supply system
US3549979A (en) * 1969-04-25 1970-12-22 Chemetron Corp Arc power supply with current level control
US3688180A (en) * 1971-01-14 1972-08-29 Hobart Brothers Co Welding apparatus

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4109130A (en) * 1971-11-30 1978-08-22 Matsushita Electric Industrial Co., Ltd. Electric welder output control device
US3992659A (en) * 1974-07-19 1976-11-16 Allmanna Svenska Elektriska Aktiebolaget High voltage direct current transmission
US4162379A (en) * 1977-02-25 1979-07-24 The Perkin-Elmer Corporation Apparatus for deriving a feedback control signal in a thermal system
US4241285A (en) * 1978-06-29 1980-12-23 Erico Products, Inc. Power supply for SMAW welding and stud welding
US4264858A (en) * 1979-05-29 1981-04-28 General Electric Company Means for regulating resistance current of complex load
US4287557A (en) * 1979-12-17 1981-09-01 General Electric Company Inverter with improved regulation
US4412277A (en) * 1982-09-03 1983-10-25 Rockwell International Corporation AC-DC Converter having an improved power factor
US4517439A (en) * 1984-05-07 1985-05-14 Colley Bruce H AC-DC welding power supply
US5157236A (en) * 1990-03-29 1992-10-20 Miller Electric Mfg. Co. Adaptive pulse mode gas metal arc welding control
US5482734A (en) * 1994-05-20 1996-01-09 The Miller Group, Ltd. Method and apparatus for controlling an electric arc spraying process
US5528010A (en) * 1994-05-20 1996-06-18 The Miller Group, Ltd. Method and apparatus for initiating electric arc spraying
US5665256A (en) * 1995-12-19 1997-09-09 The Esab Group, Inc. Cutting or welding system having phase loss detector and method of detecting phase loss for same
US6335511B1 (en) 1999-04-12 2002-01-01 Tri Tool Inc. Control method and apparatus for an arc welding system
US20060060574A1 (en) * 2003-09-08 2006-03-23 Lincoln Global, Inc. Electric arc welder and method for controlling the welding process of the welder
US7217904B2 (en) * 2003-09-08 2007-05-15 Lincoln Global, Inc. Electric arc welder and method for controlling the welding process of the welder

Also Published As

Publication number Publication date
CA1003506A (en) 1977-01-11
AU7104574A (en) 1976-01-15
BE817523A (fr) 1974-11-04
SE412715B (sv) 1980-03-17
FR2236601A1 (sv) 1975-02-07
BR7405650D0 (pt) 1975-05-20
JPS5039249A (sv) 1975-04-11
NL7409316A (nl) 1975-01-14
IT1018464B (it) 1977-09-30
DE2433275C3 (de) 1981-06-11
FR2236601B3 (sv) 1977-05-06
SE7408316L (sv) 1975-01-13
GB1468198A (en) 1977-03-23
DE2433275A1 (de) 1975-01-30
DE2433275B2 (de) 1980-09-25
CH593755A5 (sv) 1977-12-15

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