WO2023087742A1 - 提拉引弧防粘焊接控制电路及焊接电源 - Google Patents

提拉引弧防粘焊接控制电路及焊接电源 Download PDF

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WO2023087742A1
WO2023087742A1 PCT/CN2022/104302 CN2022104302W WO2023087742A1 WO 2023087742 A1 WO2023087742 A1 WO 2023087742A1 CN 2022104302 W CN2022104302 W CN 2022104302W WO 2023087742 A1 WO2023087742 A1 WO 2023087742A1
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Prior art keywords
arc
circuit
welding
inductance
arc striking
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PCT/CN2022/104302
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English (en)
French (fr)
Inventor
兰照丹
王光辉
刘礼军
王青青
陈浩
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杭州凯尔达电焊机有限公司
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Publication of WO2023087742A1 publication Critical patent/WO2023087742A1/zh

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    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac 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 triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • 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
    • B23K9/067—Starting the arc
    • B23K9/0672—Starting the arc without direct contact between electrodes
    • B23K9/0673—Ionisation of the arc gap by means of a tension with a step front (pulses or high frequency tensions)
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop

Definitions

  • the invention relates to the field of welding control, and in particular to a lifting arc striking anti-stick welding control circuit and a welding power supply.
  • Argon arc welding technology is based on the principle of ordinary arc welding, using argon gas to protect the metal welding material, and through high current to make the welding material melt into a liquid state on the base material to be welded to form a molten pool, so that the welded metal and the welding material It is a welding technology that achieves metallurgical combination of materials. Since argon gas is continuously supplied during high-temperature fusion welding, the welding materials cannot be in contact with oxygen in the air, thereby preventing the oxidation of the welding materials. Therefore, stainless steel and iron metals can be welded. .
  • High-frequency discharge arc ignition has disadvantages such as poor electromagnetic compatibility, strong interference, easy introduction of high voltage in the circuit to cause damage to devices, and interference with digital communication in the control circuit.
  • the non-high-frequency contact arc ignition mainly generates a short-circuit current through a short circuit between the tungsten needle and the welding workpiece, and then lifts the welding torch to form a welding arc.
  • excessive short-circuit current is likely to cause burning of the tungsten electrode, especially in the thin plate welding process, which may easily cause deformation or breakdown of the workpiece.
  • excessive short-circuit current will also cause the sticking of the tungsten needle when the tungsten needle is separated from the workpiece, which is not conducive to the lifting of the welding torch and the metal of the workpiece will be mixed with the tungsten needle after lifting, which seriously affects the welding operation and the workpiece. welding quality.
  • the existing method is to introduce a sufficiently large DC filter inductance into the main circuit, but too large inductance will affect the response of the system, especially for AC and DC argon arc welding machines The overvoltage protection of the secondary voltage spike and the secondary commutation AC frequency have adverse effects.
  • the present invention provides a lifting arc ignition anti-stick welding control circuit and a welding power supply for realizing stable arc ignition with small short-circuit current.
  • the present invention provides a lifting arc ignition anti-stick welding control circuit, which includes a main circuit and an arc starting circuit connected to the return electrode in parallel with the main circuit.
  • the arc circuit is turned on, and the arc circuit includes an auxiliary transformer, a constant current source, an arc inductor and an arc switch.
  • the auxiliary transformer is connected to the primary inverter output of the welding power source.
  • the constant current source is connected to the secondary side of the auxiliary transformer and includes an energy storage element, and the energy storage element limits the output current of the constant current source.
  • the arcing inductance is connected to the energy storage element and its inductance is greater than that of the main circuit arcing inductance.
  • the arc ignition switch is connected to the arc ignition inductance and the return electrode.
  • the arc ignition inductance stabilizes the arc ignition current output from the arc ignition circuit to the circuit electrode and the arc ignition current is less than the welding rated current of the main circuit; in the pulling stage, the voltage of the auxiliary transformer Output at maximum state and the pilot arc inductance is based on the pulling stable pilot arc current of the electrode.
  • the auxiliary transformer is based on a fixed pulse output, and is in a maximum state output in both the loop electrode short-circuit phase and the pull-up phase.
  • the output of the arc striking circuit is connected to the PI regulating system of the welding power source through the current sampling element, and based on the arc striking current output in the circuit electrode short circuit stage that is less than the welding rated current, the PI regulating system increases the auxiliary transformer Pulse width, the auxiliary transformer outputs at its maximum state during the pull-up phase.
  • the main circuit is opened, and the arc pilot circuit is delayed to shut down; during the delayed shut-off period, the main circuit and the arc pilot circuit are in the conduction state at the same time, and the current on the loop electrode is from The ignition current transitions to the welding rated current.
  • the arc striking circuit when the control circuit for lifting arc striking anti-stick welding is applied to DC welding, the arc striking circuit is connected to the electrode circuit in a direct current connection through the arc striking switch; when the lifting arc striking anti-stick welding control circuit When the circuit is applied to AC welding, the arc striking circuit is connected to the electrode circuit in the way of DC reverse connection through the arc striking switch.
  • the arc pilot circuit when the main circuit inverter circuit on the main circuit is a half-bridge inverter structure, the arc pilot circuit also includes an arc maintenance switch and an arc maintenance inductor, and the arc maintenance switch and arc pilot switch are formed in accordance with the topology of the main circuit
  • the arc maintaining inductance is connected between the arc maintaining switch and the constant current source, and the arc maintaining inductance and the arc striking inductance form a common mode inductance.
  • the constant current source includes four capacitors and eight diodes, and the four capacitors are used as energy storage elements. Alternate charging within the battery to increase the output voltage of the constant current source.
  • the anti-stick welding control circuit for lifting arc striking also includes an absorbing circuit.
  • the absorbing circuit includes absorbing capacitors and four freewheeling blocking diodes.
  • the absorbing capacitors are connected in parallel to the main circuit inverter circuit and the arc striking inverter. Between the transformer circuits, the two ends of the absorbing capacitor are respectively connected to the main circuit inverter circuit and the arc starting inverter circuit through four freewheeling blocking diodes.
  • the auxiliary transformer includes two secondary windings
  • the constant current source includes two capacitors and two full-bridge rectifier circuits
  • the two capacitors are used as energy storage elements
  • the two secondary windings are connected via a capacitor and A full-bridge rectifier circuit is connected to the arc pilot circuit.
  • the present invention also provides a welding power supply, which includes the above-mentioned control circuit for lifting arc striking anti-stick welding.
  • the control circuit for lifting arc striking and anti-stick welding connects the arc striking circuit in parallel with the main circuit.
  • the main circuit of the high rated welding current is closed and the arc ignition circuit is turned on.
  • the constant current source and the arc-ignition inductance on the arc-strike loop provide a stable arc-strike current that is much smaller than the rated welding current for the loop electrode, so as to realize arc strike with a small short-circuit current; at the same time, the auxiliary transformer’s The voltage is output at the maximum state.
  • the electrode loop In the pull-up stage, based on the maximum output of the auxiliary transformer and the stability of the arc-starting inductance with large inductance, the electrode loop will generate a stable arc, thereby achieving stable pull-up and starting arc at low current. Further, since the arc striking circuit is completely connected in parallel with the main circuit through the auxiliary transformer, that is, the arc striking circuit is completely independent of the main circuit. Therefore, the large inductance of the arc striking inductance on the arc striking circuit will not have any influence on the welding current characteristics of the main circuit.
  • Fig. 1 is a schematic structural diagram of a welding power source provided by Embodiment 1 of the present invention.
  • FIG. 2 is a schematic diagram of the structure of the control circuit for lifting arc ignition anti-stick welding in FIG. 1 .
  • Fig. 3 is a state diagram showing the variation of the welding circuit current with time during the DC reverse connection arc striking process in Fig. 2 .
  • Figure 4 shows the timing diagram during the arc striking process in Figure 3 .
  • Fig. 5 is a state diagram of current variation with time in the welding circuit during the arc striking process of the circuit shown in Fig. 1 in DC positive connection according to another embodiment of the present invention.
  • Figure 6 is a timing diagram of the arc striking process in Figure 5 .
  • Fig. 7 shows the structural representation of the constant current source provided by another embodiment of the present invention.
  • FIG. 8 shows the timing diagram of the switching tubes Q1, Q2, Q3, and Q4 of the welding power source during the welding process.
  • Fig. 9 is a schematic structural diagram of the welding power source provided in the second embodiment.
  • FIG. 10 is a schematic diagram of the specific structure of the anti-stick welding control circuit for lifting arc ignition in FIG. 9 .
  • the present embodiment provides a lifting arc ignition anti-stick welding control circuit 30, which includes a main circuit 1 and an arc starting circuit connected to the return electrode 3 in parallel with the main circuit 1 2.
  • the arc strike circuit 2 includes an auxiliary transformer T2, a constant current source S1, an arc strike inductor and an arc strike switch.
  • the auxiliary transformer T2 is connected to the output of the primary inverter 20 of the welding power source.
  • the constant current source S1 is connected to the secondary side of the auxiliary transformer T2 and includes an energy storage element, and the energy storage element limits the output current of the constant current source.
  • the arc starting inductance is connected to the energy storage element and its inductance is greater than the main loop inductance DCL.
  • the arc strike switch is connected to the arc strike inductance and return electrode 3 .
  • the arc strike inductance stabilizes the arc strike current output from the arc strike circuit 2 to the loop electrode 3 and the arc strike current is less than the welding rated current of the main circuit; in the pulling stage, the auxiliary transformer
  • the voltage of T2 is output at the maximum state and the arc inductance stabilizes the arc current based on the pulling of the electrode.
  • the constant current source S1 refers to a current source that determines the output current capability of the arc strike circuit 2 .
  • the energy storage elements in the constant current source S1 are four capacitors C1 , C2 , C3 and C4 .
  • the capacitive reactance of the four capacitors C1, C2, C3, and C4 as energy storage elements can be changed to determine the output current capability of the constant current source S1.
  • the present invention does not make any limitation thereto.
  • the limitation of the output current of the auxiliary transformer T2 can also be realized by other energy storage elements such as inductors or common mode inductors.
  • the arc starting inductance is at mH level
  • the main loop inductance DCL is at uH level so that the inductance of the arc starting inductance is much larger than that of the main loop inductance DCL.
  • the rated welding current of the main circuit is generally greater than 50A, and the arc striking current is less than or equal to 15A.
  • the present invention does not make any limitation thereto.
  • This implementation takes the application of the lifting arc ignition anti-stick welding control circuit to the AC welding power supply of the half-bridge inverter as an example for illustration, and its specific circuit diagram is shown in Figure 1.
  • the present invention does not make any limitation thereto.
  • the anti-stick welding control circuit provided by the present invention is also suitable for full-bridge inverter AC welding power supply or direct welding.
  • the welding power supply includes an input rectification and filtering circuit 10 , a primary inverter 20 and a lifting arc ignition anti-stick welding control circuit 30 provided in this embodiment.
  • the main circuit 1 is connected to the primary inverter 20 through the main transformer T1
  • the arc strike circuit 2 is connected to the primary inverter 20 through the auxiliary transformer T2.
  • the arc strike circuit 2 has two switching tubes Q3, Q4 and two inductors L1, L2 respectively connected to the two switching tubes.
  • the main circuit 1 is an AC welding structure with a half-bridge inverter.
  • the switching tube Q4 is used as an arc starting switch.
  • the return electrode 3 is connected to the arc strike circuit 2 in the form of DC reverse connection (DCEP, tungsten pole connected to positive), and the welding torch is connected to the positive output of the auxiliary transformer T2 through the main circuit inductance DCL, and the tungsten needle is heated during arc strike. Easier release of electrons for better arc start.
  • DCEP DC reverse connection
  • the switching tube Q3 can also be used as an arc ignition switch.
  • Fig. 5 is the waveform diagram of welding current under DC positive connection state.
  • I1 is the arc striking current
  • I2 is the welding rated current.
  • Current, time A is the short circuit between the welding torch and the workpiece, and time B is the lifting of the welding torch; the arc striking method of direct current connection is more used for direct current welding.
  • Figure 6 is a diagram of the variation of welding circuit current I with time t in the process of lifting arc ignition of each component under DC positive arc ignition, in which the switch tube Q1 and switch tube Q3 are turned on at the same time during the time period t1, and then the switch tube Q3 is turned off broken.
  • the primary inverter 20 Press the welding torch to trigger the argon arc welding torch signal, the primary inverter 20 is in the working state, at this time, the secondary side of the main transformer T1 generates output voltages U1, U2, and the switching tubes Q1 and Q2 are in the off state.
  • Auxiliary transformer T2 outputs voltage U3, U4.
  • the switching tube Q4 as the arc ignition switch is turned on, and the switching tube Q3 is turned off, and the welding power supply outputs a no-load voltage of U 40 (the voltage difference between U0 and U4).
  • the welding circuit current can only be generated through the arc ignition circuit 2. Due to the function of the constant current source S1, the inductance L2 as the arc starting inductance will flow through the arc based on the capacitance value of the energy storage element in the constant current source S1 (in this embodiment, four capacitors C1, C2, C3, C4) Current I1, the current value is less than 15A. Since the current sampling element HI detects that the arc striking current is less than the rated welding current I2, after adjustment based on the system PI control, the output voltage U40 of the auxiliary transformer T2 will be in the maximum output state.
  • the welding torch When the output voltage of the auxiliary transformer T2 is at the maximum output state, the welding torch is pulled up (as shown at time B in Figure 3 and Figure 4), the inductance L2 as the arc starting inductance stabilizes the arc starting current in the arc space, and the welding circuit will continue to generate stable welding arc.
  • the switching tube Q2 in the main circuit 1 when the switching tube Q2 in the main circuit 1 is turned on, the welding current on the arc striking circuit 2 will instantly transition to the welding rated current I2 of the main circuit 1 .
  • the welding current enters the normal preset current, the arc striking process is completed, and the switching tube Q4 serving as the arc striking switch is turned off.
  • the delayed turn-off or turn-on timing of the switch tube Q4 can be synchronously followed by the switch tube Q2 on the main circuit.
  • the timing diagram shown in Figure 4 is the signal timing diagram of the welding circuit when the arc switch Q4 synchronously follows the switch tube Q2 on the main circuit, where time A is the short circuit between the welding torch and the workpiece, time B is the lifting of the welding torch, and I1 is the arc ignition current. I2 is the welding rated current.
  • the present invention does not make any limitation thereto.
  • the arcing circuit can be closed or as shown in FIG. 4 , the arcing switch is turned off after a delay of one terminal time.
  • the small arc ignition current output by the arc ignition circuit 2 is based on the limitation of the energy storage element and the arc ignition inductance, and the arc ignition current will not be weakened
  • the voltage output state of the auxiliary transformer T2 the voltage of the auxiliary transformer T2 is always output at the maximum state or adjusted to the maximum output state based on the arc striking current. This setting enables the auxiliary transformer T2 to always provide a sufficiently high arc striking voltage for the return electrode 3 when the welding torch or welding rod is lifted.
  • the arc starting inductance (inductance L2) with a large inductance prevents the reduction of the arc starting current on the return electrode 30 when the welding torch or the electrode is lifted, so as to realize the stability of the arc starting current on the return electrode 3 .
  • Stable arc starting current and sufficiently high arc starting voltage ensure stable arc starting between return electrodes 3 when the welding torch or electrode is lifted, thereby realizing stable arc starting under low current.
  • the arc starting circuit 2 is connected to the output of the primary inverter 20 of the welding power source through the auxiliary transformer T2, and the arc starting circuit 2 and the main circuit 1 are independent of each other after being output from the primary inverter 20. without causing any disturbance. Therefore, the arc inductance (inductance L2 in Fig. 2) with large inductance on the arc striking circuit 2 will not cause any influence on the voltage characteristics and current characteristics of the main circuit 1 during normal welding; and the traditional access to the main circuit Compared with the internal supersaturated inductor, the welding start performance is better. In addition, the inductance of the main loop inductor DCL is small, which is more conducive to the control of the welding current waveform.
  • the small inductance of the main loop inductance DCL also realizes the miniaturization of the volume of the main loop.
  • the output of the arc ignition circuit 2 is connected to the PI adjustment system of the welding power source through the current sampling element HI, and the arc ignition current is less than the welding rated current during the short circuit stage of the circuit electrode 3 , the PI regulation system increases the pulse width of the auxiliary transformer T2, and the auxiliary transformer T2 outputs at the maximum state during the pull-up phase.
  • the present invention does not make any limitation thereto.
  • the auxiliary transformer when the output voltage of the auxiliary transformer at a certain pulse width is sufficient to ensure a stable pull-up arc strike, the auxiliary transformer can also be output based on a fixed pulse, which is in both the short-circuit stage of the return electrode 3 and the pull-up stage. Maximum status output.
  • the arc striking circuit 2 also includes an arc maintaining switch and an arc maintaining inductance, the arc maintaining switch and the arc striking switch form an arc striking inverter circuit with the same topology as the main circuit, and the arc maintaining inductor is connected to the arc maintaining switch Between the constant current source and the maintenance arc inductance and the starting arc inductance form a common mode inductance.
  • the switching tube Q3 is an arc-maintaining switch
  • the switching tube Q4 is an arc-starting switch
  • the inductance L1 is an arc-maintaining inductance
  • the inductance L2 is an arc-starting inductance.
  • the welding control circuit After the arc ignition is completed, the welding control circuit enters the normal AC welding state. At this time, the conduction sequence of the switch tube Q4 as the arc strike switch follows the switch tube Q2 on the main circuit synchronously, and the conduction sequence of the switch tube Q3 as the arc maintenance switch Synchronously follow the switching tube Q1 on the main circuit, the timing diagram is shown in Figure 8.
  • the common mode choke coil formed by the inductance L1 and the inductance L2 in the arcing circuit provides a reliable arc maintenance voltage for the loop electrode 3 when it reverses to the zero crossing point during the AC commutation process, and prevents the main circuit from reversely transforming to the zero crossing point. Arc break occurs.
  • the switch tube Q4 works in the arc ignition stage to realize stable lifting arc ignition under low current. After that, after entering normal welding, the switch tubes Q3 and Q4 are turned on alternately to provide the welding circuit with an AC re-ignition voltage to maintain the continuity of the arc.
  • the constant current source also includes four capacitors C1, C2, C3, C4 and eight diodes D5, D10, D11, D12, D6, D7, D8 , D9.
  • the capacitors C1 and C3 form one group, and the capacitors C2 and C4 form another group.
  • the two groups of capacitors are alternately charged in the two half cycles of the output of the auxiliary transformer T2 to increase the output voltage of the constant current source S1. Specifically, in FIG.
  • one end of the capacitors C1 and C2 is coupled to the upper end of the auxiliary transformer T2, and the other ends of the capacitors C1 and C2 are respectively coupled to the inductors L1 and L2 through the diodes D5 and D11.
  • One end of the capacitors C3 and C4 are coupled to the lower end of the auxiliary transformer T2, and the other ends of the capacitors C3 and C4 are respectively coupled to the inductors L1 and L2 through the diodes D10 and D12.
  • Diode D6 is coupled to the other end of capacitor C1 and the center tap of auxiliary transformer T2; diode D7 is coupled to the other end of capacitor C2 and the center tap of auxiliary transformer T2; diode D8 is coupled to the other end of capacitor C4 and the center tap of auxiliary transformer T2 ; The diode D9 is coupled to the other end of the capacitor C3 and the center tap of the auxiliary transformer T2.
  • the center tap of the auxiliary transformer T2 charges the capacitor C1 through the diode D6, and the capacitor C1 stores energy to generate a voltage equal to the amplitude of the output voltage UT2 of the auxiliary transformer T2 and negative on the left and positive on the right; at the same time, the lower end of the auxiliary transformer T2
  • the capacitor C3 is charged through the path from the capacitor C3 and the diode D9 to the center tap of the auxiliary transformer T2, and the two ends of the capacitor C3 generate a voltage with an amplitude of UT2 and a direction of left positive and right negative.
  • the output voltage U30 of the constant current source S1 is the sum of the output voltage of the auxiliary transformer T2 and the voltage on the capacitor C1, which is 2UT2.
  • the switch tube Q4 is turned on: the center tap of the auxiliary transformer T2 ⁇ the main circuit inductor DCL ⁇ the left end of the loop electrode ⁇ the right end of the loop electrode ⁇ the switch tube Q4 ⁇ the inductor L2 ⁇ the diode D12 ⁇ the capacitor C3 ⁇ the lower end of the auxiliary transformer T2.
  • the output voltage U40 of the constant current source S1 is the sum of the output voltage of the auxiliary transformer T2 and the voltage on the capacitor C3, which is 2UT2.
  • the upper end of the auxiliary transformer will charge the capacitor C2 through the circuit from the capacitor C2, the diode D7 to the center tap of the auxiliary transformer, and the voltage at both ends of the capacitor C2 is UT2;
  • the center tap will charge the capacitor C4 through the loop from the diode D8, the capacitor C4 to the lower end of the auxiliary transformer, and the voltage across the capacitor C4 is UT2.
  • the output voltage U40 of the constant current source S1 is the sum of the output voltage UT2 of the auxiliary transformer T2 and the voltage on the capacitor C2, which is 2UT2.
  • the center tap of the auxiliary transformer T2 charges the capacitor C1 through the diode D6 again, and the lower end of the auxiliary transformer T2 charges the capacitor C3 through the path from the capacitor C3 and the diode D9 to the center tap of the auxiliary transformer T2.
  • Capacitors C1, C2, C3, C4 and eight diodes realize the boost output of the constant current source S1, and the high voltage output of the auxiliary transformer T2 based on the auxiliary transformer winding and the constant current source S1 will have a larger design space.
  • the arc ignition voltage needs to be 100V.
  • the output voltage UT2 of the auxiliary transformer T2 can be set to 50V, and then boosted to 100V by the constant current source S1, so as to realize the miniaturization design of the circuit.
  • the constant current source S1 and the two inductors L1 and L2 will work together to provide the maintenance arc voltage when the reverse commutation direction crosses the zero point. Specifically, if the switching tube Q1 and the switching tube Q3 are turned on before the commutation; current, energy is stored in the inductor L1. Turn off the switching tube Q1 and the switching tube Q3, and both the main circuit 1 and the arcing circuit 2 enter a very short dead time. Due to the coupling effect of the common mode inductance, the inductance L2 will obtain the same magnitude of current as the inductance L1, and the left positive and right negative induced voltage UL2 will be generated on the inductance L2.
  • the output voltage of the arc strike circuit 2 is the sum of the induced voltage UL2 of the inductor L2 and the output voltage U40 (equal to 2UT2) of the constant current source S1, both of which are used together to provide High re-ignition voltage to ensure arc continuity after commutation.
  • the inverter of the main circuit commutates from the negative half-cycle zero-crossing to the AC positive half-cycle: the induced voltage UL1 on the inductance L1 will be superimposed on the output voltage U30 (equal to 2UT2) of the constant current source S1 as the output support of the arcing circuit 2 At the return electrode 3 there is a very high re-ignition voltage for the return electrode 3 after commutation.
  • the present invention does not impose any limitation on the structure of the constant current source.
  • the structure in FIG. 7 can also be used.
  • the auxiliary transformer T2 includes two secondary windings T21, T22.
  • the constant current source S1 includes two capacitors Ca, Cb and two full-bridge rectifier circuits B1, B2. Two capacitors are used as energy storage elements, and the two secondary windings are respectively connected to the arc-striking circuit through a capacitor and a full-bridge rectifier circuit.
  • the constant current source does not have the effect of boosting; the two capacitors Ca and Cb as energy storage elements limit the output current of the two secondary windings T21 and T22 and work together with the corresponding inductors L1 and L2 to achieve small Stable output of arc ignition current.
  • other energy storage elements such as inductors and common-mode inductors can also be used to realize the constant current source.
  • the lifting arc ignition anti-stick welding control circuit also includes a snubber circuit 4, and the snubber circuit 4 includes a snubber capacitor C5 and four Freewheeling blocking diodes D13, D14, D15, D16.
  • the absorbing capacitor C5 is connected in parallel between the main circuit inverter circuit and the arc striking inverter circuit, and the two ends of the absorbing capacitor C5 are respectively connected to the main circuit inverter circuit and the arc striking inverter circuit through four freewheeling blocking diodes.
  • the absorbing circuit 4 absorbs the high-voltage spikes generated when the switching tubes Q1, Q2, Q3, and Q4 are turned off, avoiding damage to the four switching tubes caused by the high-voltage peak, and the four switching tubes share one absorbing circuit 4, which greatly simplifies the structure of the circuit .
  • the switching tube Q1 and the switching tube Q3 are turned off.
  • the high-voltage peak generated by the switch tube Q1 being turned off will charge the absorbing capacitor C5 through the freewheeling blocking diodes D13 and D14 to realize the absorption of the high-voltage peak;
  • the blocking diodes D15 and D16 absorb the charging of the absorbing capacitor C5.
  • the switching tube Q2 and the switching tube Q4 are turned off.
  • the high-voltage spike generated by the switch-off of the switching tube Q2 charges the freewheeling diode on the switching tube Q1 and the freewheeling blocking diodes D13 and D14 to the absorption capacitor C5, so as to realize the absorption of the high-voltage spike.
  • the high voltage peak generated by the switch off of the switching tube Q4 is absorbed by the freewheeling diode on the switching tube Q3 and the freewheeling blocking diodes D15 and D16 to absorb the charging of the absorbing capacitor C5.
  • the snubber circuit 4 further includes a pre-charging circuit S2 connected to both ends of the snubber capacitor C5.
  • the pre-charging circuit S2 pre-charges the snubber capacitor C5 to a higher voltage, such as close to 400V.
  • the voltage across the absorption capacitor C5 will further increase to a higher voltage value (such as 430V) and be blocked by the freewheeling blocking diode D13, D14, D15, D4, and D15 are clamped, and the arc striking circuit 2 and absorbing circuit 4 provide a high maintenance arc voltage for the main circuit when the main circuit 1 reverses direction.
  • the inductance L2 will induce an induced voltage with equal amplitude and positive left and right negative.
  • the voltage across the absorbing capacitor C5 will be applied to inductor L1 , L2. Therefore, the induced voltage UL2 on the inductor L2 is half of the voltage across the absorbing capacitor C5, about 215V.
  • the induced voltage UL2 on the inductor L2 is superimposed on the output voltage U40 of the auxiliary transformer T2 and then output to the loop electrode 3, which greatly increases the maintenance arc voltage of the main loop 1 during reverse commutation. Rearcing conditions are provided.
  • the switching tubes Q2 and Q4 are turned off, the induced voltage UL1 will be generated on the inductor L1; when the switching tubes Q1 and Q3 are turned on and commutated, the induced voltage UL1 is superimposed on the output voltage U30 of the auxiliary transformer T2 and then output to the loop Electrode 3, ensures the continuity of the arc.
  • the pre-charging circuit S2 may include a pre-charging winding and a rectifier connected to the auxiliary transformer T2.
  • the pre-charging winding takes power through the auxiliary transformer T2 and pre-charges the absorption capacitor C5 to the voltage required for arc maintenance, such as about 400V, after being rectified by the rectifier.
  • the present invention does not impose any limitation on the structure of the pre-charging circuit.
  • an independent power source may also be used to precharge the snubber capacitor.
  • the pre-charged absorbing capacitor C5 also makes: during normal welding, when the power supply voltage of the main circuit 1 is lower than the voltage required for commutation (that is, the power supply voltage on the main circuit is lower than the voltage across the absorbing capacitor C5), The main circuit 1 will not charge the absorption capacitor C5, and no current flows in the absorption circuit 4, so the absorption circuit 4 will not affect the main circuit.
  • the control circuit for lifting arc striking and anti-stick welding connects the arc striking circuit in parallel with the main circuit.
  • the main circuit of the high rated welding current is closed and the arc ignition circuit is turned on.
  • the constant current source and the arc-ignition inductance on the arc-strike loop provide a stable arc-strike current that is much smaller than the rated welding current for the loop electrode, so as to realize arc strike with a small short-circuit current; at the same time, the auxiliary transformer’s The voltage is output at the maximum state.
  • the electrode loop In the pull-up stage, based on the maximum output of the auxiliary transformer and the stability of the arc-starting inductance with large inductance, the electrode loop will generate a stable arc, thereby achieving stable pull-up and starting arc at low current. Further, since the arc striking circuit is completely connected in parallel with the main circuit through the auxiliary transformer, that is, the arc striking circuit is completely independent of the main circuit. Therefore, the large inductance of the arc starting inductance on the arc starting circuit will not have any influence on the welding current characteristics of the main circuit.

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Abstract

一种提拉引弧防粘焊接控制电路(30)，包括主回路(1)和并联的引弧回路(2)。在提拉引弧期间，主回路关闭且引弧回路导通，引弧回路包括辅助变压器、定电流源、引弧电感以及引弧开关。辅助变压器连接于焊接电源的一次逆变(20)输出。定电流源连接于辅助变压器的副边且其内的储能元件限定定电流源的输出电流。引弧电感连接于储能元件且电感量大于主回路引弧电感。引弧开关连接于引弧电感和回路电极(3)。在回路电极短路阶段，基于储能元件的输出变化，引弧电感稳定引弧回路输出的引弧电流且引弧电流小于主回路的焊接额定电流；在提拉阶段，辅助变压器的电压以最大状态输出且引弧电感基于电极的提拉稳定引弧电流。还公开了一种焊接电源，引弧回路通过辅助变压器完全并联于主回路，引弧回路上的大电感量的引弧电感不会对主回路的焊接电流特性造成任何的影响。

Description

提拉引弧防粘焊接控制电路及焊接电源 技术领域
本发明涉及焊接控制领域，且特别涉及一种提拉引弧防粘焊接控制电路及焊接电源。
背景技术
氩弧焊技术是在普通电弧焊的原理的基础上，利用氩气对金属焊材的保护，通过高电流使焊材在被焊基材上融化成液态形成熔池，使被焊金属和焊材达到冶金结合的一种焊接技术，由于在高温熔融焊接中不断送上氩气，使焊材不能和空气中的氧气接触，从而防止了焊材的氧化，因此可以焊接不锈钢、铁类五金金属。由于其具有焊接热影响区窄，焊件应力、变形和裂纹倾向小，焊接过程稳定，收弧控制容易等优点，使该焊接工艺在现代工艺文明建设中起到了非常重要的作用，并得到了广泛的应用。
氩弧焊的引弧方式主要有两种：高频放电引弧和非高频接触式引弧。高频放电引弧存在电磁兼容性差，干扰性强，容易引入回路高压造成器件损坏，干扰控制回路数字通讯等弊端。
非高频接触式引弧主要通过钨针与焊接工件短路产生短路电流后再提起焊枪形成焊接电弧。但过大的短路电流容易造成钨极的烧损，特别是在薄板焊接过程中容易造成工件变形或击穿。进一步的，过大的短路电流也会造成钨针与工件脱离时存在粘钨针的现象，不仅不利于焊枪的提起且提起后的钨针上会夹杂有工件金属，严重影响了焊接操作及工件的焊接质量。如通过减小短路电流进行引弧，则在焊枪提起的过程中容易造成电弧熄灭，存在引弧成功率低的问题。为提高小电流短路引弧的成功率，现有的做法是在主回路中引入足够大的直流滤波电感，但过大的电感量会对系统的响应造成影响，特别对于交直流氩弧焊机二次电压尖峰的过压保护及二次换向交流频率产生不良影响。
发明内容
本发明为了克服现有技术的不足，提供一种实现小短路电流的稳定引弧的提拉引弧防粘焊接控制电路及焊接电源。
为了实现上述目的，本发明提供一种提拉引弧防粘焊接控制电路，其包括主回路和与主回路并联连接于回路电极的引弧回路，在提拉引弧期间，主回路关闭且引弧回路导通，引弧回路包括辅助变压器、定电流源、引弧电感以及引弧开关。辅助变压器连接于焊接电源的一次逆变输出。定电流源连接于辅助变压器的副边且包括储能元件，储能元件限定定电流源的输出电流。引弧电感连 接于储能元件且电感量大于主回路引弧电感。引弧开关连接于引弧电感和回路电极。在回路电极短路阶段，基于储能元件的输出变化，引弧电感稳定引弧回路输出至回路电极的引弧电流且引弧电流小于主回路的焊接额定电流；在提拉阶段，辅助变压器的电压以最大状态输出且引弧电感基于电极的提拉稳定引弧电流。
根据本发明的一实施例，辅助变压器基于固定脉冲输出，在回路电极短路阶段和提拉阶段均处于最大状态输出。
根据本发明的一实施例，引弧回路的输出经电流采样元件接入焊接电源的PI调节系统，基于回路电极短路阶段输出的小于焊接额定电流的引弧电流，PI调节系统增大辅助变压器的脉冲宽度，辅助变压器在提拉阶段以最大状态输出。
根据本发明的一实施例，在提拉阶段完成后主回路开通，引弧回路延迟关断；在延迟关断期间内，主回路和引弧回路同时处于导通状态，回路电极上的电流从引弧电流过渡到焊接额定电流。
根据本发明的一实施例，当提拉引弧防粘焊接控制电路应用于直流焊接时，引弧回路通过引弧开关以直流正接的方式连接于电极回路；当提拉引弧防粘焊接控制电路应用于交流焊接时，引弧回路通过引弧开关以直流反接的方式连接于电极回路。
根据本发明的一实施例，当主回路上的主回路逆变电路为半桥逆变结构时，引弧回路还包括维弧开关和维弧电感，维弧开关和引弧开关形成与主回路拓扑结构相同的引弧逆变电路，维弧电感连接于维弧开关和定电流源之间且维弧电感和引弧电感形成共模电感。
根据本发明的一实施例，定电流源包括四个电容和八个二极管，四个电容作为储能元件，四个电容两两组成一组，两组电容分别在辅助变压器输出的两个半周期内交替充电，提升定电流源的输出电压。
根据本发明的一实施例，提拉引弧防粘焊接控制电路还包括吸收电路，吸收回路包括吸收电容和四个续流阻断二极管，吸收电容并联连接于主回路逆变电路和引弧逆变电路之间，吸收电容的两端分别通过四个续流阻断二极管连接于主回路逆变电路和引弧逆变电路。
根据本发明的一实施例，辅助变压器包括两个次级绕组，定电流源包括两个电容和两个全桥整流电路，两个电容作为储能元件，两个次级绕组分别经一电容和一全桥整流电路接入引弧回路中。
另一方面，本发明还提供一种焊接电源，其包括述提拉引弧防粘焊接控制电路。
综上所述，本发明提供的提拉引弧防粘焊接控制电路通过在主回路上并联引弧回路。在提拉引弧期间，高额定焊接电流的主回路处于关闭状态且引弧回路导通。在回路电极短路阶段，引弧回路上的定电流源和引弧电感为回路电极提供一稳定的且远小于额定焊接电流的引弧电流，实现小短路电流引弧；于此同时，辅助变压器的电压以最大状态输出。在提拉阶段，基于辅助变压器的最大输出和大电感量的引弧电感对引弧电流的稳定，电极回路将产生稳定电弧，从而实现小电流下的稳定提拉引弧。进一步的，由于引弧回路通过辅助变压器完全并联于主回路，即引弧回路完全独立于主回路。故引弧回路上的大电感量的引弧电感不会对主回路的焊接电流特性造成任何的影响。
为让本发明的上述和其它目的、特征和优点能更明显易懂，下文特举较佳实施例，并配合附图，作详细说明如下。
附图说明
图1所示为本发明实施例一提供的焊接电源的具体结构示意图。
图2所示为图1中提拉引弧防粘焊接控制电路的结构示意图。
图3所示为图2在直流反接引弧过程中焊接回路电流随时间变化的状态图。
图4所示为图3引弧过程中的时序图。
图5所示为本发明另一实施例中图1所示的电路在直流正接时引弧过程中焊接回路上电流随时间变化的状态图。
图6所示为图5引弧过程中的时序图。
图7所示为本发明另一实施例提供的定电流源的结构示意
图8所示焊接电源在焊接过程中开关管Q1，Q2，Q3，Q4的时序图。
图9所示为实施例二提供的焊接电源的结构示意图。
图10所示为图9中提拉引弧防粘焊接控制电路的具体结构示意图。
具体实施方式
基于主回路的小电流提拉引弧，由于主回路上的额定焊接电流很高，在回路电极短路时会具有很高的短路电流，从而造成电极粘住的问题。为减小短路电流则需要调节主变压器的输入使主变压器处于最小输出状态。然而，在焊枪提起时最小输出状态的主变压器和迅速降低的引弧电流均无法维持电弧的稳定，电弧极易熄灭。而主回路中大电感的引入，在一定程度上会提高小电流的 引弧成功率，但引入的大电感会对主回路的电流特性和电压特性造成很大的影响。
有鉴于此，如图1和图2所示，本实施例提供一种提拉引弧防粘焊接控制电路30，其包括主回路1和与主回路1并联连接于回路电极3的引弧回路2，在提拉引弧期间，主回路1关闭且引弧回路2导通，引弧回路2包括辅助变压器T2、定电流源S1、引弧电感以及引弧开关。辅助变压器T2连接于焊接电源的一次逆变20的输出。定电流源S1连接于辅助变压器T2的副边且包括储能元件，储能元件限定定电流源的输出电流。引弧电感连接于储能元件且电感量大于主回路电感DCL。引弧开关连接于引弧电感和回路电极3。在回路电极短路阶段，基于储能元件的输出变化，引弧电感稳定引弧回路2输出至回路电极3的引弧电流且引弧电流小于主回路的焊接额定电流；在提拉阶段，辅助变压器T2的电压以最大状态输出且引弧电感基于电极的提拉而稳定引弧电流。
所述定电流源S1指的是确定引弧回路2输出电流能力的电流源。于本实施例中，如图1和图2所示，定电流源S1中储能元件为四个电容C1，C2，C3，C4。在电路设计时可通过改变作为储能元件的四个电容C1，C2，C3，C4的电容值来调整其容抗以确定定电流源S1的输出电流能力。然而，本发明对此不作任何限定。于其它实施例中，也可通过电感或共模电感等其它储能元件来实现辅助变压器T2输出电流的限制。
于本实施例中，引弧电感为mH级，主回路电感DCL则为uH级以使引弧电感的电感量远远大于主回路电感DCL的电感量。主回路额定焊接电流一般大于50A，引弧电流小于或等于15A。然而，本发明对此不作任何限定。
本实施以提拉引弧防粘焊接控制电路应用于半桥逆变的交流焊接电源为例进行说明，其具体的电路图如图1所示。然而，本发明对此不作任何限定。于其它实施例中，本发明提供的提拉引弧防粘焊接控制电路同样适用于全桥逆变的交流焊接电源或直接焊。
在图1中，焊接电源包括输入整流滤波电路10，一次逆变20以及本实施提供的提拉引弧防粘焊接控制电路30。主回路1通过主变压器T1连接于一次逆变20，引弧回路2通过辅助变压器T2连接于一次逆变20。于本实施例中，引弧回路2上具有两个开关管Q3，Q4和分别与两个开关管相连接的两个电感L1，L2。事实上，在提拉引弧阶段，引弧回路2中只需一个开关管和一个电感即可，即开关管Q3和开关管Q4中只有一个导通，而另一个开关管和另一个电感将不起作用。而本实施例中，开关管Q3，Q4以及电感L1，L2的设置则使得引弧回路 2不仅可提拉引弧且在主回路交流换向时为主回路提供维弧电压，这个而在后文中将会详细介绍。因此，于其它实施例中，如果仅仅只是基于提拉引弧的考虑而不考虑换向维弧，不管是全桥结构还是半桥结构，引弧回路上均只需设置一个开关管来作为引弧开关和一个电感来作为引弧电感即可，此时辅助变压器也无需采用带中心抽头的变压器。
于本实施中，主回路1为半桥逆变的交流焊接结构，为更有利于提拉起弧，优选的，将开关管Q4作为引弧开关。此时回路电极3以直流反接(DCEP,钨极接正)的方式接入引弧回路2中，焊枪通过主回路电感DCL连接辅助变压器T2的正极输出，在引弧时钨针被加热将更容易释放电子以更有利于提拉起弧。然而，本发明对此不作任何限定。于其它实施例中，也可将开关管Q3作为引弧开关，此时回路电极将通过开关管Q3以直流正接(DCEN,钨极接负)的方式接入引弧回路中。此时，焊枪通过主回路电感DCL连接辅助变压器的负极输出。该种结构的引弧过程与直流正接类似，区别在于，引弧电流的方向相反，图5为直流正接状态下焊接电流的波形图，在图5中，I1为引弧电流，I2为焊接额定电流，时刻A为焊枪与工件短路，时刻B为焊枪提起；直流正接的引弧方式更多的用于直流焊接。在图6为直流正接引弧下各个部件在提拉引弧过程中焊接回路电流I随时间t的变化图，其中t1时间段内开关管Q1和开关管Q3同时导通，之后开关管Q3关断。
以下将结合图2来详细介绍本实施例提供的提拉引弧防粘焊接控制电路30的具体工作原理。
按下焊枪触发氩弧焊焊枪信号，一次逆变20处于工作状态，此时主变压器T1次级产生输出电压U1，U2，开关管Q1和开关管Q2处于关闭状态。辅助变压器T2输出电压U3，U4。此时，作为引弧开关的开关管Q4导通，而开关管Q3则关断，焊接电源输出空载电压为U 40(U0与U4的电压差)。
当钨针与工件短路，如图3和图4中A时刻后，由于主回路1处于关闭状态，焊接回路电流只能通过引弧回路2产生。由于定电流源S1的作用，作为引弧电感的电感L2上会流过基于定电流源S1内储能元件(本实施例为四个电容C1，C2，C3，C4)电容值大小的引弧电流I1，电流值小于15A。由于电流采样元件HI检测到引弧电流小于焊接额定电流I2，基于系统PI控制调节后，辅助变压器T2的输出电压U 40将会处于最大输出状态。
当辅助变压器T2的输出电压处于最大输出状态，提拉焊枪(如图3和图4中B时刻)，作为引弧电感的电感L2稳定电弧空间内的引弧电流，焊接回路将 持续产生稳定的焊接电弧。与此同时，开通主回路1内的开关管Q2，引弧回路2上的焊接电流将瞬间过渡到主回路1的焊接额定电流I2。当焊接电流进入正常预置电流后，引弧过程完成，作为引弧开关的开关管Q4关闭。为保证电流过渡的稳定及可靠性，可使开关管Q4延迟关断或导通时序同步跟随主回路上的开关管Q2。图4所示的时序图为引弧开关Q4同步跟随主回路上的开关管Q2时焊接回路的信号时序图，其中时刻A为焊枪与工件短路，时刻B为焊枪提起，I1为引弧电流，I2为焊接额定电流。然而，本发明对此不作任何限定。于其它实施例中，在提拉引弧阶段完成主回路1开通后，即可关闭引弧回路或如图4所示，引弧开关延迟一端时间后关断。
本实施例提供的提拉引弧防粘焊接控制电路30中，在短路阶段下，引弧电路2输出的小引弧电流是基于储能元件和引弧电感的限制，引弧电流不会减弱辅助变压器T2的电压输出状态，辅助变压器T2的电压始终以最大状态输出或基于引弧电流而调整至最大输出状态。该设置使得在焊枪或焊条提起时，辅助变压器T2始终能为回路电极3提供足够高的引弧电压。而大电感量的引弧电感(电感L2)则在焊枪或焊条提起时，阻碍回路电极30上引弧电流的降低，实现回路电极3上引弧电流的稳定。稳定的引弧电流和足够高的引弧电压确保焊枪或焊条提起时回路电极3之间能稳定引弧，从而实现小电流下的稳定起弧。
进一步的，于本实施例中，引弧回路2通过辅助变压器T2连接于焊接电源的一次逆变20的输出，引弧回路2和主回路1从一次逆变20输出后彼此独立，两者之间不会造成任何的干扰。因此，引弧回路2上大电感量的引弧电感(图2中的电感L2)不会对主回路1在正常焊接时的电压特性和电流特性造成任何的影响；和传统的接入主回路内的过饱和电感器相比，焊接的起始性能更好。此外，主回路电感DCL电感量很小，更有利于焊接电流波形的控制，电流上升下降速度快，有效占空比大，电弧能量更加集中，可满足最大交流频率500HZ的设计需求。与此同时，主回路电感DCL电感量很小同样实现了主回路体积的小型化。
于本实施例中，为进一步提高引弧的稳定性，设置引弧回路2的输出经电流采样元件HI接入焊接电源的PI调节系统，在回路电极3短路阶段，引弧电流小于焊接额定电流，PI调节系统增大辅助变压器T2的脉冲宽度，辅助变压器T2在提拉阶段以最大状态输出。然而，本发明对此不作任何限定。于其它实施例中，当辅助变压器在某一脉宽下的输出电压足以保证稳定的提拉引弧时，辅 助变压器也可基于固定脉冲输出，其在回路电极3短路阶段和提拉阶段均处于最大状态输出。
于本实施例中，引弧回路2还包括作为维弧开关和维弧电感，维弧开关和引弧开关形成与主回路拓扑结构相同的引弧逆变电路，维弧电感连接于维弧开关和定电流源之间且维弧电感和引弧电感形成共模电感。在图2中，开关管Q3为维弧开关，开关管Q4为引弧开关；电感L1为维弧电感，电感L2为引弧电感。在引弧完成后，焊接控制电路进入正常的交流焊接状态，此时作为引弧开关的开关管Q4导通时序同步跟随主回路上的开关管Q2，作为维弧开关的开关管Q3导通时序同步跟随主回路上的开关管Q1，时序图如图8所示。引弧回路在交流换向的过程中通过电感L1和电感L2所形成的共模扼流圈为回路电极3在逆变换向过零点时提供可靠的维弧电压，防止主回路逆变换向过零点时出现断弧。即图2所示的提拉引弧防粘焊接控制电路在焊接时：首先，在引弧阶段下开关管Q4工作，实现小电流下的稳定提拉引弧。之后，在进入正常焊接后开关管Q3，Q4交替导通，为焊接回路提供交流换向的再引燃电压以保持电弧的连续性。
为进一步提高交流换向时的维弧电压，于本实施例中，定电流源还包括四个电容C1，C2，C3，C4和八个二极管D5，D10，D11，D12，D6，D7，D8，D9。其中电容C1，C3组成一组，电容C2，C4组成另一组。两组电容分别在辅助变压器T2输出的两个半周期内进行交替充电，提升定电流源S1的输出电压。具体而言，在图2中，电容C1，C2的一端耦接于辅助变压器T2的上端，电容C1，C2的另一端则分别通过二极管D5，D11耦接于电感L1，L2。电容C3，C4的一端耦接于辅助变压器T2的下端，电容C3，C4的另一端则分别通过二极管D10，D12耦接于电感L1，L2。二极管D6耦接于电容C1另一端和辅助变压器T2的中心抽头；二极管D7耦接于电容C2另一端和辅助变压器T2的中心抽头；二极管D8耦接于电容C4另一端和辅助变压器T2的中心抽头；二极管D9耦接于电容C3另一端和辅助变压器T2的中心抽头。
具体而言，在初始时刻，当辅助变压器T2输出的交流电处于负半周：
辅助变压器T2的中心抽头经二极管D6对电容C1充电，电容C1上存储能量，产生与辅助变压器T2的输出电压UT2幅值相等的且左负右正的电压；于此同时，辅助变压器T2的下端经电容C3和二极管D9到辅助变压器T2的中心抽头的通路对电容C3充电，电容C3两端产生幅值为UT2且方向为左正右负的电压。
当辅助变压器T2输出的交流电进入正半周后：①在开关管Q3导通时：辅助变压器T2的上端→电容C1→二极管D5→电感L1→开关管Q3→回路电极右端→回路电极左端→主回路电感DCL→辅助变压器中心抽头。此时，定电流源S1的输出电压U30为辅助变压器T2的输出电压和电容C1上的电压叠加之和，为2UT2。②若开关管Q4导通时：辅助变压器T2的中心抽头→主回路电感DCL→回路电极左端→回路电极右端→开关管Q4→电感L2→二极管D12→电容C3→辅助变压器T2的下端。此时，定电流源S1的输出电压U40为辅助变压器T2的输出电压和电容C3上的电压叠加之和，为2UT2。于此同时，在当辅助变压器T2输出的交流电进入正半周时辅助变压器的上端将通过电容C2，二极管D7到辅助变压器中心抽头的回路对电容C2充电，电容C2两端的电压为UT2；辅助变压器的中心抽头将通过二极管D8、电容C4到辅助变压器下端的回路对电容C4充电，电容C4的两端电压为UT2。
当辅助变压器T2输出的交流电再一次进入负半周后：①在开关管Q3导通时：辅助变压器T2的下端→电容C4→二极管D10→电感L1→开关管Q3→回路电极右端→回路电极左端→主回路电感DCL→辅助变压器中心抽头。此时，定电流源S1的输出电压U30为辅助变压器T2的输出电压UT2和电容C4上的电压叠加之和，为2UT2。②若开关管Q4导通时：辅助变压器T2的中心抽头→主回路电感DCL→回路电极左端→回路电极右端→开关管Q4→电感L2→二极管D11→电容C2→辅助变压器T2的上端。此时，定电流源S1的输出电压U40为辅助变压器T2的输出电压UT2和电容C2上的电压叠加之和，为2UT2。在这个阶段内又再次重复辅助变压器T2的中心抽头经二极管D6对电容C1充电，辅助变压器T2的下端经电容C3和二极管D9到辅助变压器T2的中心抽头的通路对电容C3充电。
电容C1，C2，C3，C4以及八个二极管实现了定电流源S1的增压输出，基于辅助变压器绕组和定电流源S1的辅助变压器T2的高压输出将具有更大的设计空间。譬如，引弧电压需要100V，此时可设置辅助变压器T2输出电压UT2为50V，然后再通过定电流源S1增压至100V，从而实现电路的小型化设计。
在主回路1逆变换向时，定电流源S1和两个电感L1，L2将共同作用，为逆变换向过零点时提供的维弧电压。具体而言，若换向之前，开关管Q1和开关管Q3导通；开关管Q2和开关管Q4关断，主回路1产生由U1流向U0的电流，引弧回路2产生由U3流向U0的电流，电感L1中存储能量。关闭开关管Q1和开关管Q3，主回路1和引弧回路2均进入极短的死区时间。由于共模电感的耦 合作用，电感L2将获得与电感L1相同大小的电流，电感L2上产生左正右负的感应电压UL2。开通开关管Q2和开关管Q4，引弧回路2的输出电压为电感L2的感应电压UL2和定电流源S1的输出电压U40(等于2UT2)之和，两者共同为主回路1换向后提供很高的再引燃电压以保证换向后电弧的连续性。
同样的，主回路逆变从负半周过零换向至交流正半周时：电感L1上的感应电压UL1将叠加于定电流源S1的输出电压U30(等于2UT2)作为引弧回路2的输出加持在回路电极3上，为回路电极3换向后条件很高的再引燃电压。
然而，本发明对定电流源的结构不作任何限定。于其它实施例中，也可采用图7中的结构。在图8中，辅助变压器T2包括两个次级绕组T21，T22。定电流源S1包括两个电容Ca，Cb和两个全桥整流电路B1，B2。两个电容作为储能元件，两个次级绕组分别经一电容和一全桥整流电路接入引弧回路中。在该电路中，定电流源没有增压的作用；作为储能元件的两个电容Ca，Cb限制两个次级绕组T21，T22的输出电流且分别与对应的电感L1，L2共同作用实现小的引弧电流的稳定输出。于其它实施例中，还可采用电感、共模电感等其它储能元件来实现定电流源。
实施例二
本实施例与实施例一及其变化基本相同，区别在于，如图9和图10所示，提拉引弧防粘焊接控制电路还包括吸收电路4，吸收回路4包括吸收电容C5和四个续流阻断二极管D13，D14，D15，D16。吸收电容C5并联连接于主回路逆变电路和引弧逆变电路之间，吸收电容C5的两端分别通过四个续流阻断二极管连接于主回路逆变电路和引弧逆变电路。吸收电路4在开关管Q1，Q2，Q3，Q4关断时吸收产生的高压尖峰，避免高压尖峰对四个开关管的损坏且四个开关管共用一个吸收回路4也极大简化了电路的结构。
具体而言，在逆变正半周过零换向至负半周时，开关管Q1和开关管Q3的关断。开关管Q1关断所产生的高压尖峰将通过续流阻断二极管D13，D14对吸收电容C5进行充电，以实现高压尖峰的吸收；而开关管Q3关断所产生的高压尖峰则通过续流阻断二极管D15，D16对吸收电容C5的充电进行吸收。同样的，在逆变负半周过零换向正负半周时，开关管Q2和开关管Q4的关断。开关管Q2关断所产生的高压尖峰将开关管Q1上的续流二极管以及续流阻断二极管D13，D14对吸收电容C5进行充电，以实现高压尖峰的吸收。而开关管Q4关断所产生的高压尖峰则通过开关管Q3上的续流二极管以及续流阻断二极管D15，D16对吸收电容C5的充电进行吸收。
于本实施例中，吸收回路4还包括连接于吸收电容C5两端的预充电电路S2。预充电电路S2将吸收电容C5预充电至更高的电压，如接近400V。开关管Q1，Q2，Q3，Q4反激出的电压尖峰对吸收电容C5进行再充电后，吸收电容C5两端的电压将进一步提升到更高的电压值(如430V)并被续流阻断二极管D13，D14，D15，D4，D15钳制，引弧回路2和吸收回路4在主回路1逆变换向时为主回路提供很高的维弧电压。
具体而言，当开关管Q1，Q3均关断时，电感L1上将会感应出左负右正的感应电压。共模电感的耦合作用，电感L2上将会感应出幅值相等的且左正右负的感应电压。基于电感L1、续流阻断二极管D15、吸收电容C5、续流阻断二极管D16、电感L2以及定电流源S1内的多个二极管所组成的回路，吸收电容C5两端电压将施加于电感L1，L2。因此，电感L2上的感应电压UL2为吸收电容C5两端电压的一半，约215V左右。
当开关管Q2，Q4导通时，电感L2上的感应电压UL2叠加于辅助变压器T2的输出电压U40后输出至回路电极3，大大提高了主回路1逆变换向时的维弧电压，为换向后再燃弧提供条件。同样的，当开关管Q2，Q4关断时，电感L1上将产生感应电压UL1；在开关管Q1，Q3导通换向时，感应电压UL1叠加于辅助变压器T2的输出电压U30后输出至回路电极3，确保了电弧的持续性。
预充电电路S2可包括连接辅助变压器T2上的预充电绕组和整流器。预充电绕组通过辅助变压器T2取电并经整流器整流后将吸收电容C5预充电至维弧所需电压，如400V左右。然而，本发明对预充电电路的结构不作任何限定。于其它实施例中，也可采用独立的电源来为吸收电容进行预充电。进一步的，预充电后的吸收电容C5也使得：在正常焊接时，当主回路1的电源电压低于换向所需电压时(即主回路上的电源电压低于吸收电容C5两端的电压)，主回路1不会对吸收电容C5充电，吸收回路4内无电流流过，故吸收回路4不会影响主回路。
综上所述，本发明提供的提拉引弧防粘焊接控制电路通过在主回路上并联引弧回路。在提拉引弧期间，高额定焊接电流的主回路处于关闭状态且引弧回路导通。在回路电极短路阶段，引弧回路上的定电流源和引弧电感为回路电极提供一稳定的且远小于额定焊接电流的引弧电流，实现小短路电流引弧；于此同时，辅助变压器的电压以最大状态输出。在提拉阶段，基于辅助变压器的最大输出和大电感量的引弧电感对引弧电流的稳定，电极回路将产生稳定电弧，从而实现小电流下的稳定提拉引弧。进一步的，由于引弧回路通过辅助变压器 完全并联于主回路，即引弧回路完全独立于主回路。故引弧回路上的大电感量的引弧电感不会对主回路的焊接电流特性造成任何的影响。
虽然本发明已由较佳实施例揭露如上，然而并非用以限定本发明，任何熟知此技艺者，在不脱离本发明的精神和范围内，可作些许的更动与润饰，因此本发明的保护范围当视权利要求书所要求保护的范围为准。

Claims (10)

  1. 一种提拉引弧防粘焊接控制电路，其特征在于，包括主回路和与主回路并联连接于回路电极的引弧回路，在提拉引弧期间，主回路关闭且引弧回路导通，所述引弧回路包括：
    辅助变压器，连接于焊接电源的一次逆变输出；
    定电流源，连接于辅助变压器的副边且包括储能元件，所述储能元件限定定电流源的输出电流；
    引弧电感，连接于储能元件且电感量大于主回路引弧电感；
    引弧开关，连接于引弧电感和回路电极；
    在回路电极短路阶段，基于储能元件的输出变化，引弧电感稳定引弧回路输出至回路电极的引弧电流且所述引弧电流小于主回路的焊接额定电流；在提拉阶段，辅助变压器的电压以最大状态输出且引弧电感基于电极的提拉稳定引弧电流。
  2. 根据权利要求1所述的提拉引弧防粘焊接控制电路，其特征在于，所述辅助变压器基于固定脉冲输出，在回路电极短路阶段和提拉阶段均处于最大状态输出。
  3. 根据权利要求1所述的提拉引弧防粘焊接控制电路，其特征在于，所述引弧回路的输出经电流采样元件接入焊接电源的PI调节系统，基于回路电极短路阶段输出的小于焊接额定电流的引弧电流，PI调节系统增大辅助变压器的脉冲宽度，辅助变压器在提拉阶段以最大状态输出。
  4. 根据权利要求1所述的提拉引弧防粘焊接控制电路，其特征在于，在提拉阶段完成后主回路开通，引弧回路延迟关断；在延迟关断期间内，主回路和引弧回路同时处于导通状态，回路电极上的电流从引弧电流过渡到焊接额定电流。
  5. 根据权利要求1所述的提拉引弧防粘焊接控制电路，其特征在于，当所述提拉引弧防粘焊接控制电路应用于直流焊接时，引弧回路通过引弧开关以直流正接的方式连接于电极回路；当所述提拉引弧防粘焊接控制电路应用于交流焊接时，引弧回路通过引弧开关以直流反接的方式连接于电极回路。
  6. 根据权利要求1所述的提拉引弧防粘焊接控制电路，其特征在于，当所述主回路上的主回路逆变电路为半桥逆变结构时，引弧回路还包括维弧开关和维弧电感，维弧开关和引弧开关形成与主回路拓扑结构相同的引弧逆变电路，维弧电感连接于维弧开关和定电流源之间且维弧电感和引弧电感形成共模电感。
  7. 根据权利要求6所述的提拉引弧防粘焊接控制电路，其特征在于，所述定电流源包括四个电容和八个二极管，四个电容作为储能元件，四个电容两两组成一组，两组电容分别在辅助变压器输出的两个半周期内交替充电，提升定电流源的输出电压。
  8. 根据权利要求6所述的提拉引弧防粘焊接控制电路，其特征在于，所述提拉引弧防粘焊接控制电路还包括吸收电路，吸收回路包括吸收电容和四个续流阻断二极管，所述吸收电容并联连接于主回路逆变电路和引弧逆变电路之间，吸收电容的两端分别通过四个续流阻断二极管连接于主回路逆变电路和引弧逆变电路。
  9. 根据权利要求6所述的提拉引弧防粘焊接控制电路，其特征在于，所述辅助变压器包括两个次级绕组，所述定电流源包括两个电容和两个全桥整流电路，两个电容作为储能元件，两个次级绕组分别经一电容和一全桥整流电路接入引弧回路中。
  10. 一种焊接电源，其特征在于，所述焊接电源包括权利要求1～9任一项所述的提拉引弧防粘焊接控制电路。
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