Auxiliary arc maintenance circuit for manual welding machine

Abstract

The invention discloses an auxiliary arc-maintaining circuit for a manual welding machine, comprising: a pulse transformer, wherein the primary side comprises a first winding and a second winding, and the input end of the first winding is connected to an AC power supply; a power management chip, wherein the power end is connected to the second winding on the primary side of the pulse transformer; an arc-maintaining current control circuit, which is respectively connected to the output end, the current sensing end and the output end of the first winding on the primary side of the pulse transformer of the power management chip; an arc-maintaining current output circuit, which is respectively connected to the secondary side of the pulse transformer and the positive output of the power circuit; and a voltage feedback circuit, which is respectively connected to the feedback voltage input end of the power management chip and the negative output of the power circuit. The invention only needs to generate a low-power arc-maintaining current through a low-power electronic device, which greatly reduces the cost; and, due to the low-power filter inductor, the main circuit of the welding machine only needs to provide an inductor with very small inductance, which reduces the cost on the main circuit of the welding machine.

Description

Technical Field

[0001] The invention relates to a manual welding machine circuit, in particular to an auxiliary arc-maintaining circuit for a manual welding machine. Background Art

[0002] Generally, for manual arc welding using cellulose electrodes, due to the characteristic of cellulose electrodes that arcs are easily broken, the no-load voltage requirements of the welding machine are relatively high, and an inductor with a large inductance needs to be connected in series at the output end of the welding machine. Increasing its no-load voltage will inevitably lead to an increase in the reverse voltage spike of the rectifier diode on the secondary rectifier side, increased diode losses, an increase in the number of secondary turns of the transformer, an increase in the current flowing in the IGBT tube on the inverter side, increased losses, and a series of other problems. To solve these problems, it is necessary to select IGBTs with high current resistance, high voltage resistance diodes, larger heat sinks, and larger welding machine sizes, and these problems will inevitably lead to a significant increase in the cost of the welding machine. Summary of the invention

[0003] According to an embodiment of the present invention, an auxiliary arc maintenance circuit for a manual welding machine is provided. The power supply circuit of the manual welding machine adopts an inverter power supply circuit. The inverter power supply circuit outputs low-voltage direct current to the manual welding machine after rectifying, inverting, reducing voltage and single-phase rectifying the AC power supply, including:

[0004] A pulse transformer, wherein the primary side of the pulse transformer comprises a first winding and a second winding, and an input end of the first winding is connected to an AC power source;

[0005] A power management chip, wherein the power supply terminal of the power management chip is connected to the second winding of the primary side of the pulse transformer;

[0006] The arc pilot current control circuit is respectively connected to the output end of the power management chip, the current sensing end and the output end of the first winding of the primary side of the pulse transformer, and is used to control the manual welding machine to output the arc pilot current;

[0007] The arc pilot current output circuit is connected to the secondary side of the pulse transformer and the positive output of the power supply circuit, and is used to output the arc pilot current to the manual welding machine;

[0008] The voltage feedback circuit is connected to the feedback voltage input terminal of the power management chip and the output negative electrode of the power circuit respectively, and is used to generate a control voltage to control the width of the arc-maintaining current pulse.

[0009] Furthermore, the arc pilot current control circuit comprises:

[0010] A power switch tube, wherein the drain of the power switch tube is connected to the output end of the first winding;

[0011] A driving resistor, wherein two ends of the driving resistor are respectively connected to the output end of the power management chip and the gate of the power switch tube;

[0012] A first sampling resistor, one end of which is connected to the source of the power switch tube and the current sensing end of the power management chip, and the other end is grounded.

[0013] Furthermore, the arc pilot current control circuit further comprises:

[0014] An absorption circuit, wherein an input end of the absorption circuit is connected to an output end of the first winding, and an output end of the absorption circuit is connected to an input end of the first winding;

[0015] The first filter circuit is arranged between the first sampling resistor and the current sensing end of the power management chip.

[0016] Furthermore, the absorption circuit includes a mixed absorption resistor, an absorption capacitor and an absorption diode. The absorption resistor and the absorption capacitor are connected in parallel and then in series with the absorption diode. The positive electrode of the absorption diode is connected to the drain of the power switch tube and the output end of the first winding, the negative electrode of the absorption diode is connected to one end of the parallel circuit of the absorption capacitor and the absorption resistor, and the other end of the parallel circuit of the absorption capacitor and the absorption resistor is connected to the input end of the first winding.

[0017] Furthermore, the first filtering circuit includes a first filtering resistor and a first filtering capacitor connected in series, the first filtering capacitor is grounded, the other end of the first filtering resistor is connected to the non-grounded end of the first sampling resistor, and the midpoint of the first filtering resistor and the first filtering capacitor is connected to the current sensing end of the power management chip.

[0018] Furthermore, the arc pilot current output circuit comprises:

[0019] A secondary diode, the anode of which is connected to the anode of the secondary side of the pulse transformer;

[0020] The filter inductor has two ends connected to the cathode of the secondary diode and the output anode of the power supply circuit respectively;

[0021] An output capacitor, wherein the positive electrode of the output capacitor is connected to the negative electrode of the secondary diode, and the negative electrode of the output capacitor is respectively connected to the negative electrode of the secondary side of the pulse transformer and the output negative electrode of the power supply circuit.

[0022] Furthermore, the voltage feedback circuit comprises:

[0023] A second sampling resistor, two ends of which are respectively connected to the negative electrode of the secondary side of the pulse transformer and the output negative electrode of the power supply circuit;

[0024] The amplifier circuit includes an amplifier and an amplifier resistor, two ends of the amplifier resistor are respectively connected to the reverse input terminal and the output terminal of the amplifier, and the reverse input terminal of the amplifier is connected to the output negative electrode of the power supply circuit and the second sampling resistor;

[0025] Voltage divider, the voltage divider is a series circuit formed by a pair of resistors connected in series, one end of the series circuit is grounded, the other end is connected to a high level, and the midpoint of the series circuit is connected to the same-direction input terminal of the amplifier;

[0026] A first photocoupler and a second photocoupler, wherein the input end of the first photocoupler is connected to the output end of the amplifier, the second photocoupler is coupled to the input through the first photocoupler, and the output end of the second photocoupler is connected to the feedback voltage input end of the power management chip;

[0027] A feedback resistor, wherein two ends of the feedback resistor are respectively connected to a feedback voltage input terminal of a power management chip and ground, and is used to generate a current in the feedback resistor to generate a feedback voltage signal.

[0028] Furthermore, the voltage feedback circuit further includes: a second filter capacitor, which is connected in parallel with the feedback resistor.

[0029] Furthermore, the voltage feedback circuit further includes: an anti-oscillation capacitor, which is arranged between the internal error amplifier terminal and the feedback voltage input terminal of the power management chip.

[0030] Furthermore, the anti-oscillation capacitor is an integrating capacitor.

[0031] According to the auxiliary arc-maintaining circuit for a manual welding machine according to the embodiment of the present invention, only a low-power arc-maintaining current needs to be generated by a low-power electronic device, and there is no need to change the main circuit of the welding machine to increase the no-load voltage, which greatly reduces the cost.

[0032] Moreover, due to the low-power filter inductor, only a very small inductor needs to be provided in the main circuit of the welding machine. Especially when the switching frequency of the welding machine is very high, even the output inductor is not required. Only the parasitic inductance on the welding cable and the grounding cable is sufficient, which reduces the cost of the main circuit of the welding machine.

[0033] It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the technology as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The schematic diagram of the auxiliary arc maintenance circuit for a manual welding machine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings to further illustrate the present invention.

[0036] First, combine Figure 1 An auxiliary arc maintenance circuit for a manual welding machine according to an embodiment of the present invention is described. The auxiliary arc maintenance circuit for a manual welding machine has a wide range of application scenarios.

[0037] like Figure 1 As shown, the auxiliary arc-maintaining circuit for a manual welding machine of the embodiment of the present invention, the power circuit of the manual welding machine adopts an inverter power circuit, the inverter power circuit outputs low-voltage direct current to the manual welding machine after rectifying, inverting, reducing and single-phase rectifying the AC power supply, and has a pulse transformer T1, a power management chip U1, an arc-maintaining current control circuit, an arc-maintaining current output circuit, and a voltage feedback circuit. In this embodiment, the power management chip U1 selects a power management chip of model UC3843.

[0038] Specifically, Figure 1 As shown, the primary side of the pulse transformer T1 includes a first winding and a second winding, and the input end of the first winding is connected to the AC power source VIN.

[0039] Specifically, Figure 1 As shown, the power supply terminal VCC of the power management chip U1 is connected to the second winding of the primary side of the pulse transformer T1. In this embodiment, a control power supply is formed by a series connection of a diode and a capacitor to supply power to the power management chip U1.

[0040] Specifically, Figure 1 As shown, the arc pilot current control circuit is respectively connected to the output terminal OUT of the power management chip U1, the current sensing terminal ISNS and the output terminal of the first winding of the primary side of the pulse transformer T1, and is used to control the manual welding machine to output the arc pilot current.

[0041] Further, if Figure 1 As shown, the arc-maintaining current control circuit includes: a power switch tube T2, a driving resistor R1, and a first sampling resistor R2. The drain D of the power switch tube T2 is connected to the output end of the first winding; the two ends of the driving resistor R1 are respectively connected to the output end OUT of the power management chip U1 and the gate G of the power switch tube T2, and the driving resistor R1 is the driving resistor of the power switch tube T2; one end of the first sampling resistor R2 is connected to the source S of the power switch tube T2 and the current sensing end ISNS of the power management chip U1, and the other end is grounded.

[0042] Further, if Figure 1 As shown, in this embodiment, the arc pilot current control circuit further includes: an absorption circuit and a first filtering circuit.

[0043] The absorption circuit includes a mixed absorption resistor R3, an absorption capacitor C1 and an absorption diode D1, which are used to absorb the voltage spike generated when the power switch tube T2 is working. The absorption resistor R3 and the absorption capacitor C1 are connected in parallel and then connected in series with the absorption diode D1. The positive electrode of the absorption diode D1, that is, the input end of the absorption circuit, is connected to the drain D of the power switch tube T2 and the output end of the first winding. The negative electrode of the absorption diode D1 is connected to one end of the parallel circuit of the absorption capacitor C1 and the absorption resistor R3. The other end of the parallel circuit of the absorption capacitor C1 and the absorption resistor R3, that is, the output end of the absorption circuit, is connected to the input end of the first winding.

[0044] The first filtering circuit includes a first filtering resistor R4 and a first filtering capacitor C2 connected in series. The first filtering capacitor C2 is grounded. The other end of the first filtering resistor R4 is connected to the non-grounded end of the first sampling resistor R2. The midpoint of the first filtering resistor R4 and the first filtering capacitor C2 is connected to the current sensing end ISNS of the power management chip U1, and the transmitted current signal is CFB1.

[0045] Specifically, Figure 1 As shown, the arc pilot current output circuit is respectively connected to the secondary side of the pulse transformer T1 and the output positive pole of the power supply circuit, and is used to output the arc pilot current to the manual welding machine.

[0046] Further, if Figure 1 As shown, the pilot arc current output circuit includes: a secondary diode D2, a filter inductor L1, and an output capacitor C3. The positive electrode of the secondary diode D2 is connected to the positive electrode of the secondary side of the pulse transformer T1; the two ends of the filter inductor L1 are respectively connected to the negative electrode of the secondary diode D2 and the positive electrode of the output of the power supply circuit; the positive electrode of the output capacitor C3 is connected to the negative electrode of the secondary diode D2, and the negative electrode of the output capacitor C3 is respectively connected to the negative electrode of the secondary side of the pulse transformer T1 and the negative electrode of the output of the power supply circuit.

[0047] Specifically, Figure 1 As shown, the voltage feedback circuit is respectively connected to the feedback voltage input terminal VFB of the power management chip U1 and the output negative electrode of the power circuit, and is used to generate a control voltage to control the width of the arc-maintaining current pulse.

[0048] Further, if Figure 1As shown, the voltage feedback circuit includes: a second sampling resistor R5, an amplifier circuit, a voltage divider, a first photocoupler U2A, a second photocoupler U2B, and a feedback resistor R6. Among them, the two ends of the second sampling resistor R5 are respectively connected to the negative electrode of the secondary side of the pulse transformer T1 and the output negative electrode of the power supply circuit; the amplifier circuit includes an amplifier U3A and an amplifier resistor R7, the two ends of the amplifier resistor R7 are respectively connected to the reverse input end and the output end of the amplifier U3A, the reverse input end of the amplifier U3A is connected to the output negative electrode of the power supply circuit and the second sampling resistor R5; the voltage divider is a series circuit formed by a pair of resistors connected in series, one end of the series circuit is grounded, and the other end is connected to a high level, the midpoint of the series circuit is connected to the same direction input end of the amplifier U3A, and the voltage divider input amplifier U3A The voltage size determines the size of the output arc-maining current of the auxiliary power supply. In the present embodiment, the high level connected to one end of the voltage divider is 15V; the input end of the first photocoupler U2A is connected to the output end of the amplifier U3A, the second photocoupler U2B is coupled input through the first photocoupler U2A, and the output end of the second photocoupler U2B is connected to the feedback voltage input end VFB of the power management chip U1; the two ends of the feedback resistor R6 are respectively connected to the feedback voltage input end VFB of the power management chip U1 and ground, so as to generate a current in the feedback resistor R6 to generate a feedback voltage signal.

[0049] Further, in this embodiment, if Figure 1 As shown, the voltage feedback circuit further includes a second filter capacitor C4 connected in parallel with the feedback resistor R6.

[0050] Further, in this embodiment, if Figure 1 As shown, the voltage feedback circuit also includes: an anti-oscillation capacitor C5, which is an integral capacitor and is arranged between the internal error amplifier terminal COMP of the power management chip U1 and the feedback voltage input terminal VFB to prevent the circuit from oscillating.

[0051] When working, the pulse transformer T1 supplies power to the power management chip U1, and the output terminal OUT of the power management chip U1 outputs current, generating a voltage at the rear end of the driving resistor R1, driving the power switch tube T2 to open, and generating current on the primary side of the pulse transformer T1, which is then output after filtering through the arc-maintaining current output circuit on the secondary side, generating a small current to assist the arc-maintaining. When the power supply voltage is abnormal, the current of the power switch tube T2 increases. When the voltage of the first sampling resistor R2 exceeds 1V, the OUT terminal of the power management chip U1 stops outputting, and the rear end of the driving resistor R1 generates a low level, which turns off the power switch tube T2 and protects the power switch tube T2.

[0052] The second sampling resistor R5 is used for auxiliary arc-maintaining current sampling. The sampling signal is input to the amplifier U3A. At the same time, the voltage divider also inputs voltage to the amplifier U3A. The output end of the amplifier U3A is amplified by the amplifying resistor R7 and connected to the input end of the first photocoupler U2A. The current signal received by the first photocoupler U2A is the current feedback signal, which is photoelectrically coupled to the second photocoupler U2B to generate current on the feedback resistor R6, thereby converting it into a feedback voltage signal. After filtering by the second filter capacitor C4, it is connected to the feedback voltage input end VFB of the power management chip U1. The power management chip U1 compares the feedback voltage signal received at the feedback voltage input end VFB with the reference voltage at the same-direction input end of the internal error amplifier COMP to generate a control voltage, thereby controlling the width of the pulse. Only low-power electronic devices are required to generate low-power arc-maintaining current, without any modification to the main circuit of the welding machine, and precise control is achieved, which greatly reduces costs and improves welding effects.

[0053] In addition, since the present embodiment has a low-power filter inductor, only an inductor with very small inductance needs to be provided in the main circuit of the welding machine. Especially when the switching frequency of the welding machine is very high, even an output inductor is not required, and only the parasitic inductance on the welding cable and the grounding cable is sufficient. This not only does not increase, but reduces the cost of the main circuit of the welding machine.

[0054] Above, refer to Figure 1 The invention describes an auxiliary arc-maintaining circuit for a manual electric welding machine according to an embodiment of the present invention. It only needs to generate a low-power arc-maintaining current through a low-power electronic device, and there is no need to change the main circuit of the electric welding machine to increase the no-load voltage, thereby greatly reducing the cost. In addition, due to the presence of a low-power filter inductor, only an inductor with very small inductance needs to be provided on the main circuit of the electric welding machine. Especially when the switching frequency of the electric welding machine is very high, there is no need for an output inductor, and only the parasitic inductance on the welding cable and the grounding cable is sufficient, thereby reducing the cost on the main circuit of the electric welding machine.

[0055] It should be noted that, in this specification, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprises..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0056] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. An auxiliary arc-maintaining circuit for a manual welding machine, wherein the power supply circuit of the manual welding machine adopts an inverter power supply circuit, and the inverter power supply circuit outputs low-voltage direct current to the manual welding machine after rectifying, inverting, stepping down and single-phase rectifying the AC power supply, characterized in that: Include: A pulse transformer, wherein the primary side of the pulse transformer comprises a first winding and a second winding, and an input end of the first winding is connected to the AC power supply; A power management chip, wherein a power supply terminal of the power management chip is connected to the second winding of the primary side of the pulse transformer; An arc pilot current control circuit, the arc pilot current control circuit is respectively connected to the output end of the power management chip, the current sensing end and the output end of the first winding of the primary side of the pulse transformer, and is used to control the manual welding machine to output the arc pilot current; An arc pilot current output circuit, the arc pilot current output circuit is respectively connected to the secondary side of the pulse transformer and the output positive electrode of the power supply circuit, and is used to output the arc pilot current to the manual welding machine; A voltage feedback circuit, the voltage feedback circuit is respectively connected to the feedback voltage input terminal of the power management chip and the output negative electrode of the power circuit, and is used to generate a control voltage to control the width of the arc-maintaining current pulse; The arc pilot current control circuit comprises: A power switch tube, wherein the drain of the power switch tube is connected to the output end of the first winding; A driving resistor, wherein two ends of the driving resistor are respectively connected to the output end of the power management chip and the gate of the power switch tube; A first sampling resistor, one end of which is connected to the source of the power switch tube and the current sensing end of the power management chip, and the other end is grounded; The arc pilot current control circuit further comprises: an absorption circuit, wherein an input end of the absorption circuit is connected to an output end of the first winding, and an output end of the absorption circuit is connected to an input end of the first winding; A first filter circuit, wherein the first filter circuit is arranged between the first sampling resistor and a current sensing end of the power management chip; The absorption circuit comprises a mixed absorption resistor, an absorption capacitor and an absorption diode, wherein the absorption resistor and the absorption capacitor are connected in parallel and then connected in series with the absorption diode, the positive electrode of the absorption diode is connected to the drain of the power switch tube and the output end of the first winding, the negative electrode of the absorption diode is connected to one end of the parallel circuit of the absorption capacitor and the absorption resistor, and the other end of the parallel circuit of the absorption capacitor and the absorption resistor is connected to the input end of the first winding; The first filter circuit comprises a first filter resistor and a first filter capacitor connected in series, the first filter capacitor is grounded, the other end of the first filter resistor is connected to the non-grounded end of the first sampling resistor, and the midpoint between the first filter resistor and the first filter capacitor is connected to the current sensing end of the power management chip; The arc pilot current output circuit comprises: A secondary diode, wherein the positive electrode of the secondary diode is connected to the positive electrode of the secondary side of the pulse transformer; A filter inductor, two ends of which are connected to the cathode of the secondary diode and the output anode of the power supply circuit respectively; An output capacitor, wherein the positive electrode of the output capacitor is connected to the negative electrode of the secondary diode, and the negative electrode of the output capacitor is respectively connected to the negative electrode of the secondary side of the pulse transformer and the output negative electrode of the power supply circuit; The voltage feedback circuit comprises: A second sampling resistor, two ends of which are respectively connected to the negative electrode of the secondary side of the pulse transformer and the output negative electrode of the power supply circuit; an amplifier circuit, the amplifier circuit comprising an amplifier and an amplifier resistor, the two ends of the amplifier resistor are respectively connected to the reverse input end and the output end of the amplifier, and the reverse input end of the amplifier is connected to the output cathode of the power supply circuit and the second sampling resistor; A voltage divider, wherein the voltage divider is a series circuit formed by a pair of resistors connected in series, one end of the series circuit is grounded, the other end is connected to a high level, and the midpoint of the series circuit is connected to the same-direction input terminal of the amplifier; A first photoelectric coupler and a second photoelectric coupler, wherein an input end of the first photoelectric coupler is connected to an output end of the amplifier, an input of the second photoelectric coupler is coupled through the first photoelectric coupler, and an output end of the second photoelectric coupler is connected to a feedback voltage input end of the power management chip; A feedback resistor, two ends of which are respectively connected to a feedback voltage input terminal of the power management chip and ground, and are used to generate a current in the feedback resistor to generate a feedback voltage signal; The voltage feedback circuit further comprises: a second filter capacitor, the second filter capacitor being connected in parallel with the feedback resistor; The voltage feedback circuit further comprises an anti-oscillation capacitor, which is arranged between the internal error amplifier terminal and the feedback voltage input terminal of the power management chip; The anti-oscillation capacitor is an integrating capacitor.

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