Welding control circuit for large-current submerged-arc welding power supply

Abstract

The utility model discloses a welding control circuit for a high-current submerged-arc welding power supply, which can prevent a workpiece from being burnt through by an arc strike by limiting an arc strike current in an arc strike stage, and can prevent the workpiece from being burnt through by releasing the limitation after the arc strike succeeds. The problems that in the prior art, due to the fact that a welding power source is provided with a change-over switch, operability is complex, and filament welding and large current welding cannot be met at the same time are solved. The device is high in reliability, and can effectively prevent a large-current submerged-arc welding power supply from arcing to burn through a workpiece; the structure is simple, cost is low, and welders can use conveniently.

Description

TECHNICAL FIELD

[0001] The utility model relates to welding technical field, concretely relates to a welding control circuit for large current submerged arc welding power supply. BACKGROUND

[0002] Submerged arc welding technology is a kind of process widely used in large welding piece welding, and it has many advantages such as high production efficiency, good weld quality and high mechanization degree.In actual welding operation, different welding current process parameters need to be switched to meet the corresponding welding requirements for different types of workpieces.This puts forward higher requirements for the maximum output current of the welding power supply, and generally, the maximum output current of the welding power supply should reach more than 1300A to adapt to the welding needs of various workpieces.

[0003] However, when using the welding power supply with output capacity reaching 2000A to weld thin wire (diameter ≤4mm), some technical problems will be faced.Because the instantaneous starting current is greater than 2000A, when welding thin wire, the excessive starting current will cause the welding wire to break, and then re-arc is needed.This not only makes the arc process longer, but also the excessive welding current is easy to burn through the arc point when re-arc, causing welding defects during arc, seriously affecting the welding quality and welding efficiency, and bringing many inconveniences and troubles to actual welding production.

[0004] In the prior art, the welding power supply usually adopts direct setting of the change-over switch, and when welding thin wire, the change-over switch is set to the minimum range, however, when the change-over switch is set to the minimum range, the welding power supply cannot weld large current.The processing of the welding power supply in the prior art not only increases the complexity of operation, but also if the welder forgets to switch the change-over switch during welding, it will cause welding defects, thus making the welding quality poor. UTILITY MODEL CONTENTS

[0005] Based on the problems proposed in the above background technology, the purpose of the utility model is to provide a welding control circuit for large current submerged arc welding power supply, which limits the arc current during the arc stage to avoid arc burning through the workpiece, and releases the limitation after successful arc, solving the problem that the change-over switch of the welding power supply in the prior art leads to complex operation and cannot meet the welding of thin wire while meeting the welding of large current.

[0006] The utility model realizes the following technical scheme:

[0007] A welding control circuit for large current submerged arc welding power supply, the welding control circuit comprises: a power frequency rectifier circuit, a medium frequency inverter circuit, a medium frequency rectifier circuit and a welding machine output circuit connected in sequence, and further comprises:

[0008] A current signal acquisition circuit and a voltage signal acquisition circuit connected with the welding machine output circuit;

[0009] An arc striking current control circuit connected with the current signal acquisition circuit and the voltage signal acquisition circuit;

[0010] The arc striking current control circuit is configured to perform arc striking control on the current signal and the arc voltage signal collected by the current signal acquisition circuit and the voltage signal acquisition circuit, and generate an arc striking control signal.

[0011] The arc striking control signal is configured to perform current control on the intermediate frequency inverter circuit.

[0012] In the above technical solution, the welding control circuit provides the current signal acquisition circuit, the voltage signal acquisition circuit and the arc striking current control circuit on the basis of the existing circuit. The voltage signal output by the welding machine output circuit is collected through the current signal acquisition circuit and the voltage signal acquisition circuit.

[0013] When the welding machine is started but the welding wire does not contact the workpiece, the output voltage is the no-load voltage. At this time, there is no current signal and only the voltage signal, which is determined as the non-arc striking state. When the welding wire contacts the workpiece but the arc striking is not successful, the output voltage signal is low (close to 0V) and the current signal can be detected, which is determined as the arc striking state. When the arc is established between the welding wire and the workpiece, the output voltage rises to above 20V and the current signal always exists, which is determined as the arc striking successful state.

[0014] The collected current signal and arc voltage signal are processed by the arc striking current control circuit to determine whether the welding machine is in the non-arc striking state, the arc striking state or the arc striking successful state. Then, the output current is limited according to the state of the welding machine. Before the arc striking is successful, the output current is limited in a certain range. After the arc striking is successful, the limitation is released. In the non-arc striking state and the arc striking state, the current output by the arc striking current control circuit is limited and less than the rated output current. At this time, the welding current output by the welding machine output circuit is limited and the problem of burning through the arc striking point due to the excessive welding current is avoided. In the arc striking successful state, the current output by the arc striking current control circuit returns to the rated output current. At this time, the welding current output by the welding machine output circuit returns to the welding large current. Through the arc striking current control circuit, the problem that the welding power supply sets the switch in the prior art and thus the operability is complex and the welding thin wire and the welding large current cannot be met at the same time is avoided.

[0015] In an optional embodiment, the arc striking current control circuit comprises:

[0016] An arc striking module connected with the current signal acquisition circuit and the voltage signal acquisition circuit, the arc striking module being configured to determine whether the arc striking is successful.

[0017] an integrated operational amplifier N2A connected with the arc striking module, and a current limiting module connected with the integrated operational amplifier N2A; wherein the integrated operational amplifier N2A is configured to control the current limiting module to limit output current according to an output signal of the arc striking module.

[0018] In an optional embodiment, the current limiting circuit comprises an optical coupler N1.

[0019] An input end of the optical coupler N1 is connected with the integrated operational amplifier N2A through a resistor R4.

[0020] An output end of the optical coupler N1 is connected with a voltage dividing unit.

[0021] The voltage dividing unit is configured to divide the output signal of the optical coupler N1 to limit output current.

[0022] In an optional embodiment, the voltage dividing unit comprises a resistor R1, a resistor R2 and a resistor R3.

[0023] The first end of the resistor R1 and the first end of the resistor R2 are connected with the first output port of the optical coupler N1; the second end of the resistor R2 is grounded; the first end of the resistor R3 is connected with the second output port of the optical coupler N1; and the second end of the resistor R3 is grounded.

[0024] In an optional embodiment, the resistance of the resistor R3 is determined by the size of the welding wire diameter.

[0025] In an optional embodiment, the arc striking module comprises an integrated operational amplifier N2B.

[0026] An arc voltage signal processing unit and a current signal processing unit are connected with the integrated operational amplifier N2B.

[0027] The input end of the arc voltage signal processing unit is connected with the voltage signal acquisition circuit, and the input end of the current signal processing unit is connected with the current signal acquisition circuit.

[0028] In an optional embodiment, the arc voltage signal processing unit comprises a resistor R8, a resistor R10, a resistor R11, an integrated operational amplifier N2C and a diode D1.

[0029] The negative input port of the integrated operational amplifier N2C is connected with the arc voltage signal acquisition circuit through the resistor R10; the positive input port of the integrated operational amplifier N2C receives a reference voltage through the resistor R11; the output port of the integrated operational amplifier N2C is connected with the anode of the diode D1 through the resistor R8; and the cathode of the diode D1 is connected with the negative input port of the integrated operational amplifier N2B.

[0030] In an alternative embodiment, the current signal processing unit comprises: a resistor R9, a resistor R12, a resistor R13, an integrated operational amplifier N2D, and a diode D2.

[0031] The negative input port of the integrated operational amplifier N2D is connected with the current signal collection circuit through the resistor R13; the positive input port of the integrated operational amplifier N2D receives a reference voltage through the resistor R12; the output port of the integrated operational amplifier N2D is connected with the anode of the diode D2 through the resistor R9; and the cathode of the diode D2 is connected with the negative input port of the integrated operational amplifier N2B.

[0032] In an alternative embodiment, the positive input port of the integrated operational amplifier N2B receives a reference voltage through a resistor R7.

[0033] In an alternative embodiment, the output port of the integrated operational amplifier N2B is connected with the negative input port of the integrated operational amplifier N2A through a resistor R6, and the positive input port of the integrated operational amplifier N2A receives a reference voltage through a resistor R5.

[0034] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0035] 1. By limiting the arc starting current in the arc starting stage, the arc starting from the workpiece is avoided, and after the arc starting is successful, the limitation is released, thereby solving the problem that the welding power supply sets a switch in the prior art, thereby leading to complex operability and being unable to meet the welding of thin wires while meeting the welding of large currents;

[0036] 2. High reliability, which can effectively avoid the arc starting from burning through the workpiece of the large current submerged arc welding power supply;

[0037] 3. Simple structure, low cost, and convenient for welders to use. BRIEF DESCRIPTION OF DRAWINGS

[0038] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0039] Figure 1 A principle schematic view of a welding control circuit for a large current submerged arc welding power supply provided by the embodiment 1 of the present application;

[0040] Figure 2 A circuit schematic view of an arc starting current control circuit provided by the embodiment 1 of the present application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the utility model more clearly, the utility model is described in detail in one optional embodiment below combined with examples and drawings, the schematic implementation mode of the utility model and its description are only used for explaining the utility model, and do not serve as the limitation of the utility model.

[0042] Embodiment 1

[0043] The embodiment 1 provides a welding control circuit for a large-current submerged arc welding power supply, as shown in a welding control circuit for a large-current submerged arc welding power supply, the welding control circuit comprises: a power frequency rectifier circuit, a medium frequency inverter circuit, a medium frequency rectifier circuit and a welding machine output circuit connected in sequence, and further comprises: Figure 1

[0044] A current signal acquisition circuit and a voltage signal acquisition circuit connected with the welding machine output circuit;

[0045] An arc starting current control circuit connected with the current signal acquisition circuit and the voltage signal acquisition circuit;

[0046] The arc starting current control circuit is used for carrying out arc starting control on the current signal and the arc voltage signal collected by the current signal acquisition circuit and the voltage signal acquisition circuit, and generates an arc starting control signal.

[0047] The arc starting control signal is used for carrying out current control on the medium frequency inverter circuit.

[0048] It should be noted that the welding power supply adopts a power frequency rectifier circuit, a medium frequency inverter circuit, a medium frequency rectifier circuit and a welding machine output circuit to realize, and in the prior art, a change-over switch is usually arranged in the welding power supply, when welding a thin wire, the change-over switch is turned to the minimum range to avoid the problems of long arc starting process, too large welding current, burnt-out starting point and the like caused by the fact that the instantaneous starting current is greater than 2000A.

[0049] In view of the defects in the prior art, the utility model provides a welding control circuit for a large-current submerged arc welding power supply, and the welding control circuit provides a current signal acquisition circuit, a voltage signal acquisition circuit and an arc starting current control circuit on the basis of the existing circuit. The voltage signal output by the welding machine output circuit is collected through the current signal acquisition circuit and the voltage signal acquisition circuit.

[0050] ​Wherein, after the welding machine is started, but before the welding wire contacts the workpiece, the output voltage is the no-load voltage. At this time, there is no current signal, only the voltage signal, and it is judged as not starting the arc; after the welding wire contacts the workpiece but before the arc is successfully started, the output voltage signal is low (close to 0V), and the current signal can be detected, and it is judged as the arc starting state; after the arc is established between the welding wire and the workpiece, the output voltage rises to above 20V, and the current signal always exists, and it can be judged as the arc starting success state.

[0051] The arc starting current control circuit processes the collected current signal and arc voltage signal, judges the state of the welding machine as the arc not starting state, the arc starting state or the arc starting success state, and then outputs the current limitation according to the state of the welding machine. Before the arc is successfully started, the output current is limited in a certain range, and after the arc is successfully started, the limitation is released. In the arc not starting state and the arc starting state, the current output by the arc starting current control circuit is limited and less than the rated output current. At this time, the welding current output by the welding machine output circuit is limited, and the problem of the welding current being too large to burn the starting point is avoided. In the arc starting success state, the current output by the arc starting current control circuit returns to the rated output current. At this time, the welding current output by the welding machine output circuit returns to realize the welding of large current. Through the arc starting current control circuit, the problem that the welding power supply sets the switch in the prior art, resulting in complex operation and being unable to meet the welding of thin wires while meeting the welding of large current, is avoided.

[0052] In an optional embodiment, the arc starting current control circuit comprises:

[0053] An arc starting module connected with the current signal acquisition circuit and the voltage signal acquisition circuit, the arc starting module being configured to judge whether the arc is successfully started;

[0054] An integrated operational amplifier N2A connected with the arc starting module and a current limiting module connected with the integrated operational amplifier N2A, wherein the integrated operational amplifier N2A is configured to control the current limiting module to limit the output current according to the output signal of the arc starting module.

[0055] As shown in Figure 2 The arc starting current control circuit mainly comprises three modules, the first module being the arc starting module, the arc starting module being connected with the current signal acquisition circuit and the voltage signal acquisition circuit, the current signal and the arc voltage signal being processed by the arc starting module, and the state of the welding machine being judged as the arc not starting state, the arc starting state or the arc starting success state. Then the judged state is input into the integrated operational amplifier N2A through the voltage signal, the integrated operational amplifier N2A controls whether the current limiting module limits the current and limits the current in what range, thereby realizing the function of limiting the output current.

[0056] In an alternative embodiment, the current limiting circuit comprises: an optocoupler N1;

[0057] An input end of the optocoupler N1 is connected with the integrated operational amplifier N2A through a resistor R4;

[0058] An output end of the optocoupler N1 is connected with a voltage dividing unit;

[0059] The voltage dividing unit is configured to divide the output signal of the optocoupler N1 to limit the output current.

[0060] In an alternative embodiment, the voltage dividing unit comprises: a resistor R1, a resistor R2 and a resistor R3;

[0061] The first end of the resistor R1 and the first end of the resistor R2 are connected with the first output port of the optocoupler N1; the second end of the resistor R2 is grounded; the first end of the resistor R3 is connected with the second output port of the optocoupler N1; and the second end of the resistor R3 is grounded.

[0062] In the embodiment, the current limiting circuit is implemented by the optocoupler N1, the resistor R4 and the voltage dividing unit. The optocoupler N1 is controlled by the integrated operational amplifier N2A to be turned on or off, and the current limiting is realized by the voltage dividing unit. The voltage dividing unit comprises the resistor R1, the resistor R2 and the resistor R3. The current limiting signal voltage is generated by the voltage dividing of the resistor R1 and the resistor R2, and the output current is limited to the rated value. In the embodiment, the rated value is 2000A.

[0063] Specifically, when the optocoupler N1 is turned on, the resistor R3 is connected in parallel with the resistor R2, the voltage dividing resistor is reduced, the current limiting signal voltage is lowered, and the output current is limited to the optimal arc starting value. In the embodiment, the optimal arc starting value is 1300A.

[0064] When the arc starting is unsuccessful, i.e. the arc voltage signal and the current signal do not exist at the same time, the output end of the integrated operational amplifier N2A outputs a high level, the optocoupler N1 is turned on, and the welding machine output current is limited to avoid the welding current being too large to burn through the arc starting point.

[0065] Further, the unsuccessful arc starting in the embodiment includes the following three states:

[0066] 1. The starting state without output voltage and current;

[0067] 2. The welding machine output voltage, but the welding wire does not contact the workpiece, which is the empty load state;

[0068] 3. The welding wire is short-circuited with the workpiece, and the output current is large and the output voltage is close to zero.

[0069] Only when the output current and the arc starting voltage reach a certain value, it can be determined that the arc starting is successful, and at this time, the current limiting circuit releases the limitation on the current.

[0070] In an alternative embodiment, the resistance of the resistor R3 is determined by the size of the welding wire diameter.

[0071] It should be noted that the resistance of the resistor R3 can be changed to change the optimal arc starting current value according to different welding wire diameters.

[0072] In an alternative embodiment, the arc starting module comprises an integrated operational amplifier N2B.

[0073] An arc voltage signal processing unit and a current signal processing unit connected to the integrated operational amplifier N2B.

[0074] The input end of the arc voltage signal processing unit is connected to the voltage signal acquisition circuit, and the input end of the current signal processing unit is connected to the current signal acquisition circuit.

[0075] In an alternative embodiment, the arc voltage signal processing unit comprises a resistor R8, a resistor R10, a resistor R11, an integrated operational amplifier N2C, and a diode D1.

[0076] The negative input port of the integrated operational amplifier N2C is connected to the arc voltage signal acquisition circuit through the resistor R10; the positive input port of the integrated operational amplifier N2C receives a reference voltage through the resistor R11; the output port of the integrated operational amplifier N2C is connected to the anode of the diode D1 through the resistor R8; and the cathode of the diode D1 is connected to the negative input port of the integrated operational amplifier N2B.

[0077] In an alternative embodiment, the current signal processing unit comprises a resistor R9, a resistor R12, a resistor R13, an integrated operational amplifier N2D, and a diode D2.

[0078] The negative input port of the integrated operational amplifier N2D is connected to the current signal acquisition circuit through the resistor R13; the positive input port of the integrated operational amplifier N2D receives a reference voltage through the resistor R12; the output port of the integrated operational amplifier N2D is connected to the anode of the diode D2 through the resistor R9; and the cathode of the diode D2 is connected to the negative input port of the integrated operational amplifier N2B.

[0079] In an alternative embodiment, the positive input port of the integrated operational amplifier N2B receives a reference voltage through the resistor R7.

[0080] In an alternative embodiment, the output port of the integrated operational amplifier N2B is connected to the negative input port of the integrated operational amplifier N2A through the resistor R6, and the positive input port of the integrated operational amplifier N2A receives a reference voltage through the resistor R5.

[0081] In the embodiment, the arc striking module mainly includes three parts. The first part is an arc voltage signal processing unit, which is used for receiving and processing the arc voltage signal. The second part is a current signal processing unit, which is used for receiving and processing the current signal. The third part is an integrated operational amplifier N2B, which is used for judging the output signals of the arc voltage signal processing unit and the current signal processing unit to determine whether the welding machine is in the successful arc striking state.

[0082] Further, the arc voltage signal is input to the negative input port of the integrated operational amplifier N2C through the resistor R10, and the reference voltage is input to the positive input port of the integrated operational amplifier N2C through the resistor R11. When the arc voltage signal is less than the reference voltage signal, it is the first state or the third state of the unsuccessful arc striking. At this time, the integrated operational amplifier N2C outputs a high level, which is input to the negative input port of the integrated operational amplifier N2B through the resistor R8 and the diode D1. At this time, the integrated operational amplifier N2B outputs a low level, the integrated operational amplifier outputs a high level, the optocoupler N1 is turned on, and the output current is limited.

[0083] The current signal is input to the negative input port of the integrated operational amplifier N2D through the resistor R13, and the reference voltage is input to the positive input port of the integrated operational amplifier N2D through the resistor R12. When the current signal is less than the reference voltage signal, it is the first state or the second state of the unsuccessful arc striking. At this time, the integrated operational amplifier N2D outputs a high level, which is input to the negative input port of the integrated operational amplifier N2B through the resistor R9 and the diode D2. At this time, the integrated operational amplifier N2B outputs a low level, the integrated operational amplifier N2A outputs a high level, the optocoupler N1 is turned on, and the output current is limited.

[0084] Further, the diode D1 is used to avoid the output of the integrated operational amplifier N2D being a low level when only the current signal is present, so as to pull down the high level of the output of the integrated operational amplifier and limit the output current. The diode D2 is used to avoid the output of the integrated operational amplifier N2C being a low level when only the arc voltage signal is present, so as to pull down the high level of the output of the integrated operational amplifier N2D.

[0085] Only when the welding state is present, i.e. the arc voltage signal is greater than the arc voltage signal reference value, and the current signal is greater than the current signal reference value, the integrated operational amplifier N2C and the integrated operational amplifier N2D simultaneously output a low level, the integrated operational amplifier N2B outputs a high level, the integrated operational amplifier N2A outputs a low level, the 3th pin and the 4th pin of the optocoupler N1 are cut off, the current limiting signal voltage is increased, and the output current can be removed from the limitation and restored to the rated output current.

[0086] In the embodiment, the arc voltage signal reference value is 15V, and the current signal reference value is 375A.

[0087] The above specific embodiments explain the purpose, technical scheme and beneficial effects of the present application in further detail, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A welding control circuit for a high current submerged arc welding power source, the welding control circuit comprising: The power frequency rectifier circuit, the intermediate frequency inverter circuit, the intermediate frequency rectifier circuit and the welding machine output circuit are connected in sequence, and the welding machine further comprises: A current signal acquisition circuit and a voltage signal acquisition circuit connected with the welding machine output circuit; An arc starting current control circuit connected with the current signal acquisition circuit and the voltage signal acquisition circuit; The arc starting current control circuit is used for performing arc starting control on the current signal and the arc voltage signal collected by the current signal acquisition circuit and the voltage signal acquisition circuit, and generates an arc starting control signal; The arc starting control signal is used for performing current control on the intermediate frequency inverter circuit.

2. A welding control circuit for a high current submerged arc welding power source as defined in claim 1, wherein, The arc starting current control circuit comprises: An arc starting module connected with the current signal acquisition circuit and the voltage signal acquisition circuit, which is used for judging whether the arc starting is successful; An integrated operational amplifier N2A connected with the arc starting module, and a current limiting module connected with the integrated operational amplifier N2A; the integrated operational amplifier N2A is used for controlling the current limiting module to perform output current limiting according to the output signal of the arc starting module.

3. A welding control circuit for a high current submerged arc welding power source as defined in claim 2, wherein, The current limiting circuit comprises an optical coupler N1; An input end of the optical coupler N1 is connected with the integrated operational amplifier N2A through a resistor R4; An output end of the optical coupler N1 is connected with a voltage dividing unit; The voltage dividing unit is used for dividing the output signal of the optical coupler N1 to limit the output current.

4. A welding control circuit for a high current submerged arc welding power source as defined in claim 3, wherein, The voltage dividing unit comprises resistors R1, R2 and R3; A first end of the resistor R1 and a first end of the resistor R2 are connected with a first output port of the optical coupler N1; a second end of the resistor R2 is grounded; a first end of the resistor R3 is connected with a second output port of the optical coupler N1; and a second end of the resistor R3 is grounded.

5. A welding control circuit for a high current submerged arc welding power source as defined in claim 4, wherein, The resistance of the resistor R3 is determined by the size of the welding wire diameter.

6. A welding control circuit for a high current submerged arc welding power supply as defined in claim 2, wherein, The arc starting module comprises an integrated operational amplifier N2B; An arc voltage signal processing unit and a current signal processing unit connected with the integrated operational amplifier N2B; An input end of the arc voltage signal processing unit is connected with the voltage signal acquisition circuit, and an input end of the current signal processing unit is connected with the current signal acquisition circuit.

7. A welding control circuit for a high current submerged arc welding power source as defined in claim 6, wherein, The arc voltage signal processing unit comprises resistors R8, R10, R11, an integrated operational amplifier N2C and a diode D1; A negative input port of the integrated operational amplifier N2C is connected with the arc voltage signal acquisition circuit through the resistor R10; a positive input port of the integrated operational amplifier N2C receives a reference voltage through the resistor R11; an output port of the integrated operational amplifier N2C is connected with an anode of the diode D1 through the resistor R8; and a cathode of the diode D1 is connected with a negative input port of the integrated operational amplifier N2B.

8. A welding control circuit for a high current submerged arc welding power source as defined in claim 6, wherein, The current signal processing unit comprises resistors R9, R12, R13, an integrated operational amplifier N2D and a diode D2; The negative input port of the integrated operational amplifier N2D is connected with the current signal collection circuit through the resistor R13; the positive input port of the integrated operational amplifier N2D receives a reference voltage through the resistor R12; the output port of the integrated operational amplifier N2D is connected with the anode of the diode D2 through the resistor R9; and the cathode of the diode D2 is connected with the negative input port of the integrated operational amplifier N2B.

9. A welding control circuit for a high current submerged arc welding power source as defined in claim 6, wherein, The positive input port of the integrated operational amplifier N2B receives a reference voltage through the resistor R7.

10. A welding control circuit for a high current submerged arc welding power source as defined in claim 6, wherein, The output port of the integrated operational amplifier N2B is connected with the negative input port of the integrated operational amplifier N2A through the resistor R6, and the positive input port of the integrated operational amplifier N2A receives a reference voltage through the resistor R5.

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