Spot welding machine and control circuit thereof

Abstract

The embodiment of the utility model discloses a spot welding machine and a control circuit thereof. The control circuit comprises a micro-control unit, a direct-current power supply, a charging module, a capacitor module, a boosting module, a power MOS (Metal Oxide Semiconductor) tube module, an MOS tube driving module, a key module, a voltage detection module, a voltage reduction and stabilization module and a spot welding trigger detection module, the micro-control unit is connected with the charging module, the voltage detection module, the step-down and voltage-stabilizing module, the key module and the spot welding trigger detection module, the voltage detection module is connected with the capacitor module, and the direct-current power supply is connected with the charging module, the step-up module and the step-down and voltage-stabilizing module; the boost module is connected with the MOS tube driving module, the MOS tube driving module is connected with the power MOS tube module, the power MOS tube module is connected with the negative electrode of a spot welding pen of the spot welding machine, the capacitor module is respectively connected with the power MOS tube module and the positive electrode of the spot welding pen of the spot welding machine, and therefore the power supply circuit can meet the requirement for operation when no mains supply exists or power is cut off.

Description

TECHNICAL FIELD

[0001] The utility model relates to spot welding machine technical field especially point welding machine and control circuit thereof. BACKGROUND

[0002] Spot welding machine is a kind of metal connecting equipment, when working, two electrodes press workpiece to make two layers of metal form certain contact resistance under the pressure of two electrodes, and when welding current flows through another electrode, instantaneous hot fusion is formed at two contact resistance points, forming welding effect.In the prior art, the main components of spot welding machine include transformer, controller and welding head.Controller is the core component of spot welding machine, responsible for adjusting current and voltage;Welding head is the part directly contacting the object to be welded, providing current and pressure;Transformer is responsible for converting AC 220V voltage of city network into suitable voltage and current for welding, so the current spot welding machine is usually connected to mains by connector for use, which cannot meet the operation when there is no mains power supply or power failure, is inconvenient to carry, and due to the limitation of connecting line, the use space is limited, which is inconvenient to move flexibly. SUMMARY

[0003] The utility model embodiment provides a kind of spot welding machine and control circuit thereof, can satisfy the operation when there is no mains power supply or power failure, is conducive to the miniaturization of spot welding machine and can avoid the space limitation of connecting line, so that spot welding machine can be moved flexibly.

[0004] In order to achieve the above purpose, the utility model embodiment provides a kind of control circuit of spot welding machine, including micro control unit, direct current power supply, charging module, capacitor module, boost module, power MOS tube module, MOS tube drive module, button module, voltage detection module, voltage reduction and stabilization module and spot welding trigger detection module;

[0005] The micro control unit is connected with charging module, voltage detection module, voltage reduction and stabilization module, button module and spot welding trigger detection module respectively, the voltage detection module is connected with the capacitor module, and the direct current power supply is connected with charging module, boost module and voltage reduction and stabilization module respectively;The boost module is connected with MOS tube drive module, the MOS tube drive module is connected with power MOS tube module, the power MOS tube module is connected with the negative pole of spot welding pen of spot welding machine, and the capacitor module is connected with power MOS tube module and the positive pole of spot welding pen of spot welding machine respectively.

[0006] Further, it further includes charging self-balancing module, buzzer module, temperature sensor, display module and foot switch module;The micro control unit is connected with the buzzer module, temperature sensor, display module and foot switch module respectively, the temperature sensor is connected with power MOS tube module, and the charging self-balancing module is connected with capacitor module.

[0007] Further, the micro control unit includes chip U1, resistor R41, resistor R42 and capacitor C12, the 4th pin of chip U1 is connected with working voltage VCC through resistor R42, the 31st pin of chip U1 is grounded through resistor R41, and the 5th pin of chip U1 is grounded through capacitor C12.

[0008] Further, the voltage reduction stabilizing module includes chip U11, stabilizing diode D5, magnetic bead L1, capacitor C2, capacitor C3 and resistor R40; the positive pole of stabilizing diode D5 is connected with the positive pole of direct current power supply, the negative pole of stabilizing diode D5 is connected with the 3rd pin of chip U11 through magnetic bead L1, one end of capacitor C2 is connected with the 3rd pin of chip U11, the other end is grounded, the 2nd pin and the 4th pin of chip U11 are both connected with one end of resistor R40, the other end of resistor R40 outputs working voltage VCC and is grounded through capacitor C3;

[0009] The voltage increasing module includes chip U2, resistor R1, resistor R2, stabilizing diode D1, stabilizing diode D2, stabilizing diode D3, inductor L2, capacitor C4 and capacitor C5; the 1st pin of chip U2 is connected with the positive pole of stabilizing diode D2 and one end of inductor L2, the negative pole of stabilizing diode D2 outputs driving voltage and is connected with one end of resistor R1 and one end of capacitor C5, the other end of resistor R1 is connected with the 3rd pin of chip U2, the other end of capacitor C5 is connected with the 2nd pin of chip U2, one end of resistor R2 is connected with the 3rd pin of chip U2, the other end of resistor R2 and the 2nd pin of chip U2 are grounded, the other end of inductor L2, one end of capacitor C4 and the negative pole of stabilizing diode D1 are all connected with the 5th pin of chip U2, the other end of capacitor C4 is grounded, the positive pole of stabilizing diode D1 is connected with the positive pole of direct current power supply, the negative pole of stabilizing diode D3 is connected with the 4th pin of chip U2, and the positive pole is connected with the 3rd pin of chip U1.

[0010] Further, the power MOS tube module includes MOS tube Q1-Q10, the MOS tube driving module includes resistor R12, resistor R13, resistor R14 and photo-coupler chip U4, the 1st pin of photo-coupler chip U4 is connected with the 2nd pin of chip U1, the 2nd pin of photo-coupler chip U4 is grounded through resistor R13, the 4th pin of photo-coupler chip U4 is connected with driving voltage, the 3rd pin of photo-coupler chip U4 is connected with one end of resistor R14 and the gate of MOS tube Q1-Q10 through resistor R12, the other end of resistor R14 is grounded and connected with the source of MOS tube Q1-Q10, and the drain of MOS tube Q1-Q10 is connected with the negative pole of point welding pen.

[0011] Further, the key module comprises an encoder SW1, a resistor R47, a resistor R48, a resistor R49, a capacitor C14, a capacitor C15, a capacitor C16, and a capacitor C17; the A pin of the encoder SW1 is connected to the 22 pin of the chip U1, one end of the resistor R49 and one end of the capacitor C15 are both connected to the A pin of the encoder SW1, the other end of the resistor R49 is connected to the working voltage VCC, one end of the resistor R48 is connected to the working voltage VCC, the other end of the resistor R48 is connected to the B pin of the encoder SW1, the other end of the capacitor C15 is grounded, one end of the capacitor C16 is connected to the B pin of the encoder SW1, the other end of the capacitor C16 is grounded, the B pin of the encoder SW1 is connected to the 21 pin of the chip U1, the D pin of the encoder SW1 is connected to the 30 pin of the chip U1, the D pin of the encoder SW1 is further connected to the working voltage VCC through the resistor R47, and is grounded through the capacitor C14, and the E pin of the encoder SW1 is grounded.

[0012] Further, the capacitor module comprises a capacitor group, the capacitor group comprises two super-farad capacitors connected in series, and the voltage detection module comprises a resistor R36, a resistor R37, a resistor R38, a resistor R39, a capacitor C7, and a capacitor C8; one end of the resistor R36 is connected to the positive pole CAP+ of the capacitor group, the other end of the resistor R36 and one end of the resistor R37 and one end of the capacitor C7 are connected to the 25 pin of the chip U1, the other end of the resistor R37 and the other end of the capacitor C7 are grounded; one end of the resistor R38 is connected to the series node CAPM of the capacitor group, the other end of the resistor R38 and one end of the resistor R39 and one end of the capacitor C8 are connected to the 26 pin of the chip U1, the other end of the resistor R39 and the other end of the capacitor C8 are grounded.

[0013] The foot switch module comprises an optocoupler chip U14, a resistor R50, a resistor R51, a resistor R52, a foot switch connecting seat DC1, and a capacitor C18; the 1 pin of the optocoupler chip U14 is connected to the working voltage VCC through the resistor R50, the 2 pin of the optocoupler chip U14 is connected to the 1 pin of the foot switch connecting seat DC1, the 3 pin of the foot switch connecting seat DC1 is grounded through the resistor R52, the 4 pin of the optocoupler chip U14 is connected to the 28 pin of the chip U1 and is connected to the working voltage VCC through the resistor R51, one end of the capacitor C18 is connected to the 4 pin of the optocoupler chip U14, and the other end of the capacitor C18 and the 3 pin of the optocoupler chip U14 are both grounded.

[0014] The spot welding trigger detection module comprises a diode D4, a resistor R7, and a resistor R8; the negative pole of the diode D4 and one end of the resistor R7 are connected to the negative pole of the spot welding pen, the other end of the resistor R7 and one end of the resistor R8 are connected to the 8 pin of the chip U1, the positive pole of the diode D4 and the other end of the resistor R8 are grounded.

[0015] Further, the charging module comprises chip U7, chip U8, diode D6, voltage stabilizing diode D7, diode D8, resistor R61-R67, inductor L3, capacitor C1, and triode Q12; one end of capacitor C1 is connected to the 4th pin of chip U7 and the 5th pin of chip U8, and the other end of capacitor C1 is connected to analog ground; the 3rd pin and the 6th pin of chip U8 are both connected to the negative electrode of diode D8, and the positive electrode of diode D8 is connected to one end of resistor R65 and the 1st pin of chip U8; the other end of resistor R65 is connected to the 4th pin of chip U8 and one end of resistor R64; the other end of resistor R64 is connected to the 2nd pin of chip U7; one end of resistor R61, one end of resistor R62, and the negative electrode of voltage stabilizing diode D7 are all connected to the 2nd pin of chip U8; the positive electrode of voltage stabilizing diode D7 is connected to the 3rd pin of chip U7 through resistor R63; the other end of resistor R61 is connected to the positive electrode of diode D6, one end of capacitor C19, and one end of inductor L3; the other end of inductor L3 is connected to the 6th pin of chip U8; the other end of resistor R62 and the other end of capacitor C19 are connected to analog ground; the negative electrode of diode D6 outputs charging voltage; the 1st pin of chip U7 is the collector of triode Q12; the emitter of triode Q12 is connected to one end of resistor R67 and working voltage VCC; the other end of resistor R67 and one end of resistor R66 are connected to the base of triode Q12; one end of resistor R66 is connected to the 15th pin of chip U1.

[0016] Further, the capacitor module comprises a capacitor group, and the capacitor group comprises two super-farad capacitors connected in series; the charging self-balancing module comprises chip U5, chip U6, resistor R15-R36, triode Q14, triode Q17, MOS tube Q15, and MOS tube Q16.

[0017] One end of resistor R15, one end of resistor R21, one end of resistor R23, one end of resistor R24, one end of resistor R25, one end of resistor R26, one end of resistor R27, and the emitter of triode Q14 are all connected to the series node CAPM of the capacitor group; the other end of resistor R15 and one end of resistor R16 are connected to the 1st pin of chip U5; the other end of resistor R16, the 3rd pin of chip U5, one end of resistor R22, and the source of MOS tube Q15 are all connected to ground; the 2nd pin of chip U5 is connected to the other end of resistor R21 and one end of resistor R19; the other end of resistor R19 is connected to the base of triode Q14; the collector of triode Q14 is connected to one end of resistor R20; the other end of resistor R20 and the other end of resistor R22 are connected to the gate of MOS tube Q15; the drain of MOS tube Q15 is connected to the other end of resistor R23, the other end of resistor R24, the other end of resistor R25, the other end of resistor R26, and the other end of resistor R27.

[0018] One end of the resistor R17, one end of the resistor R34, one end of the resistor R28, one end of the resistor R29, one end of the resistor R30, one end of the resistor R31, one end of the resistor R32, the emitter of the transistor Q17 are connected with the positive pole CAP+ of the capacitor group, the other end of the resistor R17 is connected with the 1 pin of the chip U6, the other end of the resistor R18 is connected with the 3 pin of the chip U6, one end of the resistor R35 and the source of the MOS tube Q16, the 2 pin of the chip U6 is connected with the other end of the resistor R34 and one end of the resistor R33, the other end of the resistor R33 is connected with the base of the transistor Q17, one end of the resistor R36 is connected with the collector of the transistor Q17, the other end of the resistor R36 and the other end of the resistor R35 are connected with the gate of the MOS tube Q16, the drain of the MOS tube Q16 is connected with the other end of the resistor R28, the other end of the resistor R29, the other end of the resistor R30, the other end of the resistor R31 and the other end of the resistor R32.

[0019] The utility model embodiment further provides a spot welding machine, including the control circuit described above.

[0020] Beneficial effect: the spot welding machine control circuit of the utility model, through utilizing direct current power supply provides the electric energy required for work, thereby can satisfy the operation when there is no commercial power supply or power failure, is favorable to the miniaturization of spot welding machine and can avoid the space restriction of connecting line, makes spot welding machine can move flexibly. BRIEF DESCRIPTION OF DRAWINGS

[0021] The technical scheme and beneficial effects of the utility model will be obvious by the following detailed description of the specific implementation of the utility model combined with the drawings.

[0022] Figure 1 It is the control circuit structure schematic view of spot welding of the utility model,

[0023] Figure 2-1 It is the circuit diagram of micro control unit of the utility model,

[0024] Figure 2-2 It is the circuit diagram of reference voltage generation module of the utility model,

[0025] Figure 3 It is the circuit diagram of voltage reduction stabilizing module of the utility model,

[0026] Figure 4 It is the circuit diagram of voltage increasing module of the utility model,

[0027] Figure 5 It is the circuit diagram of power MOS tube module and MOS tube drive module of the utility model,

[0028] Figure 6is a circuit diagram of the key module of the utility model;

[0029] Figure 7 is a circuit diagram of the voltage detection module of the utility model;

[0030] Figure 8 is a circuit diagram of the foot switch module of the utility model;

[0031] Figure 9 is a circuit diagram of the spot welding trigger detection module of the utility model;

[0032] Figure 10 is a circuit diagram of the charging module of the utility model;

[0033] Figure 11 is a circuit diagram of the buzzer module of the utility model;

[0034] Figure 12 is a circuit diagram of the temperature sensor of the utility model;

[0035] Figure 13 is a circuit diagram of the display module of the utility model;

[0036] Figure 14 is a circuit diagram of the charging self-balancing module of the utility model;

[0037] Figure 15 is a circuit diagram of the protection module of the utility model. DETAILED DESCRIPTION

[0038] Reference will now be made to the drawings, in which the same reference numerals are used to represent the same components throughout the various illustrations. The principles of the present application are illustrated in the context of a suitable operating environment. The following description is based on the example of the present application as illustrated and should not be taken as limiting the other embodiments of the present application not detailed herein.

[0039] Referring to Figure 1 , the control circuit 100 of the spot welding machine of the utility model embodiment includes a micro control unit 11, a direct current power supply 12, a charging module 13, a capacitor module 14, a voltage boosting module 15, a power MOS tube module 16, a MOS tube drive module 17, a key module 18, a voltage detection module 19, a voltage reducing and stabilizing module 21 and a spot welding trigger detection module 22.

[0040] The micro control unit 11 is connected with the charging module 13, the voltage detection module 19, the voltage reduction and stabilization module 21, the key module 18 and the spot welding trigger detection module 22 respectively, the voltage detection module 19 is connected with the capacitor module 14, and the direct current power supply 12 is connected with the charging module 13, the voltage increasing module 15 and the voltage reduction and stabilization module 21 respectively; the voltage increasing module 15 is connected with the MOS tube driving module 17, the MOS tube driving module 17 is connected with the power MOS tube module 16, and the power MOS tube module 16 is connected with the negative electrode of the spot welding pen of the spot welding machine; the capacitor module 14 is connected with the power MOS tube module 16 and the positive electrode of the spot welding pen of the spot welding machine respectively.

[0041] Further referring to Figure 1 , the control circuit 100 further comprises a charging self-balancing module 23, a buzzer module 24, a temperature sensor 25, a display module 26 and a foot switch module 27; the micro control unit 11 is connected with the buzzer module 24, the temperature sensor 25, the display module 26 and the foot switch module 27 respectively, the temperature sensor 25 is connected with the power MOS tube module 16, and the charging self-balancing module 23 is connected with the capacitor module 14.

[0042] The direct current power supply 12 can be a linear power supply, an adjustable direct current power supply, a fixed direct current power supply, a battery-powered direct current power supply or a solar direct current power supply; for example, for the battery-powered direct current power supply, the battery can be a lithium battery, and the lithium battery is connected with the charging port of the spot welding machine, so that the charging of the lithium battery can be realized. The voltage increasing module 15 is used for providing driving power for the MOS tube driving module 17, and the voltage reduction and stabilization module 21 is used for converting the output voltage of the direct current power supply 12 into a stable working voltage VCC, so as to provide a suitable working voltage for the micro control unit 11.

[0043] The spot welding machine control circuit 100 of the utility model, through utilizing direct current power supply 12 provides the electric energy required for working, thereby can satisfy the work of no commercial power supply or power failure, is favorable to the miniaturization of spot welding machine and can avoid the space restriction of connecting line, makes spot welding machine can move flexibly.

[0044] As shown in Figure 2-1 , the micro control unit 11 comprises a chip U1, a resistor R41, a resistor R42 and a capacitor C12, the 4th pin of the chip U1 is connected with the working voltage VCC through the resistor R42, the 31st pin of the chip U1 is grounded through the resistor R41, and the 5th pin of the chip U1 is grounded through the capacitor C12. Further, the 5th pin of the chip U1 is also connected with a reference voltage VREF, as shown in Figure 2-2As shown, the control circuit 100 also includes a reference voltage generation module, which includes a chip U12 and a resistor R44. Pin 1 of the chip U12 is connected to one end of the resistor R44, and the other end of the resistor R44 is connected to the operating voltage VCC. Pin 3 of the chip U12 is grounded, and pin 2 of the chip U12 is connected to pin 1 and outputs a reference voltage VREF.

[0045] like Figure 3 As shown, the buck regulator module 21 includes a chip U11, a Zener diode D5, a ferrite bead L1, capacitors C2 and C3, and a resistor R40. The anode of the Zener diode D5 is connected to the anode of the DC power supply 12, which outputs a supply voltage V12. The cathode of the Zener diode D5 is connected to pin 3 of the chip U11 via the ferrite bead L1. One end of the capacitor C2 is connected to pin 3 of the chip U11, and the other end is grounded. Pins 2 and 4 of the chip U11 are connected to one end of the resistor R40, and the other end of the resistor R40 outputs the operating voltage VCC, which is grounded via capacitor C3. The buck regulator module 21 converts the high voltage output from the DC power supply 12 into a 3.3V operating voltage, i.e., VCC, thereby powering the microcontroller unit 11 and its peripheral circuits.

[0046] like Figure 4 As shown, the boost module 15 includes chip U2, resistors R1 and R2, Zener diodes D1, D2, and D3, inductor L2, capacitor C4, and capacitor C5.

[0047] Pin 1 of chip U2 is connected to the anode of Zener diode D2 and one end of inductor L2. The cathode of Zener diode D2 outputs a drive voltage V15, which is connected to one end of resistor R1 and one end of capacitor C5. The other end of resistor R1 is connected to pin 3 of chip U2, and the other end of capacitor C5 is connected to pin 2 of chip U2. One end of resistor R2 is connected to pin 3 of chip U2, and the other end of resistor R2 and pin 2 of chip U2 are grounded. The other end of inductor L2, one end of capacitor C4, and the cathode of Zener diode D1 are all connected to pin 5 of chip U2. The other end of capacitor C4 is grounded. The anode of Zener diode D1 is connected to the anode of DC power supply 12. The cathode of Zener diode D3 is connected to pin 4 of chip U2, and its anode is connected to pin 3 of chip U1. The boost module 15 can boost the voltage output from DC power supply 12 to provide a 15V drive voltage for the power MOSFET module 16.

[0048] like Figure 5As shown, the power MOSFET module 16 includes MOSFETs Q1 to Q10, and the MOSFET driver module 17 includes resistors R12, R13, and R14, and an optocoupler chip U4. Pin 1 of the optocoupler chip U4 is connected to pin 2 of chip U1. Pin 2 of the optocoupler chip U4 is grounded through resistor R13. Pin 4 of the optocoupler chip U4 is connected to the driving voltage V15. Pin 3 of the optocoupler chip U4 is connected to one end of resistor R14 and the gate of MOSFETs Q1 to Q10 through resistor R12. The other end of resistor R14 is grounded and connected to the source of MOSFETs Q1 to Q10. The drain of MOSFETs Q1 to Q10 is connected to the negative terminal PEN- of the soldering pen.

[0049] like Figure 6 As shown, the button module 18 includes encoder SW1, resistors R47, R48, and R49, and capacitors C14, C15, C16, and C17. The A pin of encoder SW1 is connected to pin 22 of chip U1. One end of resistor R49 and one end of capacitor C15 are both connected to pin A of encoder SW1. The other end of resistor R49 is connected to the operating voltage VCC. One end of resistor R48 is connected to the operating voltage VCC, and the other end is connected to pin B of encoder SW1. The other end of capacitor C15 is grounded. One end of capacitor C16 is connected to pin B of encoder SW1, and the other end is grounded. Pin B of encoder SW1 is connected to pin 21 of chip U1. Pin D of encoder SW1 is connected to pin 30 of chip U1. Pin D of encoder SW1 is also connected to the operating voltage VCC through resistor R47 and grounded through capacitor C14. Pin E of encoder SW1 is grounded. Encoder SW1 is an encoder with a tactile switch function, which can adjust the output pulse width, trigger delay, and trigger mode during spot welding. The triggering modes include manual triggering mode and automatic triggering mode. In manual triggering mode, soldering can be manually triggered via foot switch module 27.

[0050] Capacitor module 14 includes a capacitor bank, wherein capacitors can be combined Figure 14 The capacitor bank consists of two supercapacitors C21 and C22 connected in series. CAP+ indicates the positive terminal of the capacitor bank or is connected to the positive terminal of the capacitor bank. CAPM indicates the series connection point of the capacitor bank or is connected to the series connection point of the capacitor bank. For example... Figure 7As shown, the voltage detection module 19 includes resistors R36, R37, R38, R39, capacitors C7 and C8; one end of the resistor R36 is connected to the positive pole CAP+ of the capacitor group, the other end of the resistor R36 and one end of the resistor R37, one end of the capacitor C7 are connected to the 25 pin of the chip U1, the other end of the resistor R37 and the other end of the capacitor C7 are grounded; one end of the resistor R38 is connected to the series node CAPM of the capacitor group, the other end of the resistor R38 and one end of the resistor R39, one end of the capacitor C8 are connected to the 26 pin of the chip U1, the other end of the resistor R39 and the other end of the capacitor C8 are grounded. When the micro control unit 11 detects that the super farad capacitors C21 and C22 are abnormal through the voltage detection module 19, the control charging module 13 stops charging the capacitor group.

[0051] As shown in Figure 8 The foot switch module 27 includes an optocoupler chip U14, resistors R50, R51, R52, a foot switch connecting seat DC1 and a capacitor C18, the 1 pin of the optocoupler chip U14 is connected to the working voltage VCC through the resistor R50, the 2 pin of the optocoupler chip U14 is connected to the 1 pin of the foot switch connecting seat DC1, the 3 pin of the foot switch connecting seat DC1 is grounded through the resistor R52, the 4 pin of the optocoupler chip U14 is connected to the 28 pin of the chip U1 and the working voltage VCC through the resistor R51, one end of the capacitor C18 is connected to the 4 pin of the optocoupler chip U14, and the other end of the capacitor C18 and the 3 pin of the optocoupler chip U14 are both grounded. The foot switch module 27 is connected with the external foot switch through the foot switch connecting seat DC1, and is used for triggering detection in the manual triggering mode.

[0052] As shown in Figure 9 The spot welding trigger detection module 22 includes a diode D4, a resistor R7 and a resistor R8, the negative pole of the diode D4 and one end of the resistor R7 are connected to the negative pole PEN- of the spot welding pen, the other end of the resistor R7 and one end of the resistor R8 are connected to the 8 pin of the chip U1, the positive pole of the diode D4 and the other end of the resistor R8 are grounded. When the automatic triggering mode, whether the positive pole and the negative pole of the spot welding pen contact the welding workpiece is detected by the spot welding trigger detection module 22: when the spot welding pen negative pole PEN- and the spot welding pen positive pole (connected to the positive pole CAP+ of the capacitor group) contact the welding workpiece at the same time, the spot welding pen negative pole PEN- voltage is pulled high, the TRI signal is pulled high, and the chip U1 triggers the spot welding when detecting that the TRI signal is high level through the 8 pin. The diode D4 is an anti-static diode, which can release the static electricity generated by the negative pole of the spot welding pen in the working process, and prevent damage to the internal circuit.

[0053] As shown in Figure 10As shown, the charging module 13 includes chip U7, chip U8, diode D6, voltage regulator diode D7, diode D8, resistor R61~resistor R67, inductor L3, capacitor C1, triode Q12; one end of capacitor C1 is connected to the positive pole of DC power supply 12 through 4th pin of chip U7 and 5th pin of chip U8, the other end of capacitor C1 is connected to analog ground, 3rd pin and 6th pin of chip U8 are both connected to the negative pole of diode D8, the positive pole of diode D8 is connected to one end of resistor R65 and 1st pin of chip U8, the other end of resistor R65 is connected to ground through 4th pin of chip U8 and one end of resistor R64, the other end of resistor R64 is connected to 2nd pin of chip U7, one end of resistor R61, one end of resistor R62 and the negative pole of voltage regulator diode D7 are all connected to 2nd pin of chip U8, the positive pole of voltage regulator diode D7 is connected to 3rd pin of chip U7 through resistor R63, the other end of resistor R61 is connected to the positive pole of diode D6, one end of capacitor C19 and one end of inductor L3, the other end of inductor L3 is connected to 6th pin of chip U8, the other end of resistor R62 and the other end of capacitor C19 are connected to analog ground, the negative pole of diode D6 outputs charging voltage V5.2, 1st pin of chip U7 is the collector of triode Q12, the emitter of triode Q12 is connected to one end of resistor R67 and working voltage VCC, the other end of resistor R67 and one end of resistor R66 are both connected to the base of triode Q12, one end of resistor R66 is connected to 15th pin of chip U1.

[0054] Through the action of charging module 13, 5.2V-5A cross current charging can be provided for the capacitor group (super farad capacitors C21 and C22), resistor R66 is connected to 15th pin of chip U1, and the charging of the capacitor group can be controlled by chip U1: when the signal CHRG_EN output by 15th pin of chip U1 is low, triode Q12 is turned on, then optocoupler chip U7 is turned on, the voltage feedback pin 2 (FB) of switching power supply chip U8 is pulled high, at this time, charging module 13 stops output; on the contrary, when the signal CHRG_EN is low, charging module 13 starts output, and the capacitor group is charged.

[0055] As shown in Figure 11 Buzzer module 24 includes resistor R3, resistor R4, triode Q11 and buzzer BUZZER1, one end of resistor R3 is connected to working voltage VCC, the other end is connected to 1st pin of buzzer BUZZER1, 2nd pin of buzzer BUZZER1 is connected to the collector of triode Q11, the emitter of triode Q11 is connected to ground, and the base is connected to 29th pin of chip U1 through resistor R4.

[0056] As shown in Figure 12As shown, the temperature sensor 25 includes a resistor R9, a thermistor NTC, and a capacitor C6. One end of the resistor R9 is connected to the operating voltage VCC, and the other end is connected to one end of the thermistor NTC, one end of the capacitor C6, and pin 7 of the chip U1. The other ends of the thermistor NTC and the other end of the capacitor C6 are grounded. When the microcontroller unit 11 detects an abnormal temperature through the temperature sensor 25, it stops working to prevent damage to the power MOSFETs Q1 to Q10.

[0057] like Figure 13 As shown, the display module 26 includes a chip FPC1, resistors R10 and R11, a transistor Q13, and a resistor array RN1 consisting of four resistors. Pin 3 of the chip FPC1 is connected to the collector of the transistor Q13 through resistor R10. Pin 5 of the chip FPC1 is connected to the emitter of the transistor Q13 and grounded. The base of the transistor Q13 is connected to pin 18 of the chip U1 through resistor R11. Pins 6, 7, 8, and 9 of the FPC1 chip are connected to pins 9, 10, 13, and 11 of the chip U1, respectively. The common pin of the resistor array RN1 is connected to the operating voltage VCC. The four pins of the resistor array RN1 are connected to pins 7, 8, 9, and 12 of the chip FPC1, respectively. Pin 12 of the chip FPC1 is connected to pin 14 of the chip U1.

[0058] like Figure 14 As shown, the charging self-balancing module 23 includes chip U5, chip U6, resistors R15 to R36, transistor Q14, transistor Q17, MOSFET Q15 and MOSFET Q16.

[0059] One end of resistor R15, one end of resistors R21, R23, R24, R25, R26, and R27, and the emitter of transistor Q14 are all connected to the series node CAPM of the capacitor bank. The other end of resistor R15 and one end of resistor R16 are connected to pin 1 of chip U5. The other end of resistor R16, pin 3 of chip U5, one end of resistor R22, and the source of MOSFET Q15 are all grounded. Pin 2 of chip U5 is connected to the other end of resistor R21 and one end of resistor R19. The other end of resistor R19 is connected to the base of transistor Q14. The collector of transistor Q14 is connected to one end of resistor R20. The other ends of resistors R20 and R22 are connected to the gate of MOSFET Q15. The drain of MOSFET Q15 is connected to the other ends of resistors R23, R24, R25, R26, and R27.

[0060] One end of resistor R17, one end of resistors R34, R28, R29, R30, R31, and R32, and the emitter of transistor Q17 are all connected to the positive terminal CAP+ of the capacitor bank. The positive terminal CAP+ of the capacitor bank is shorted to the charging voltage V5.2. The other end of resistor R17 and one end of resistor R18 are connected to pin 1 of chip U6. The other end of resistor R18 is connected to pin 3 of chip U6, one end of resistor R35, and the source of MOSFET Q16. Connect the capacitor bank to the series node CAPM. Connect pin 2 of chip U6 to the other end of resistor R34 and one end of resistor R33. Connect the other end of resistor R33 to the base of transistor Q17. Connect the collector of transistor Q17 to one end of resistor R36. Connect the other ends of resistor R36 and resistor R35 to the gate of MOSFET Q16. Connect the drain of MOSFET Q16 to the other ends of resistors R28, R29, R30, R31, and R32.

[0061] The charging self-balancing module 23 can prevent the capacitor bank from overcharging during the charging process. When the supercapacitor C21 is overcharged, transistor Q17 turns on, which in turn turns on MOSFET Q16, allowing discharge through resistors R28 to R32 and MOSFET Q16; when the supercapacitor C22 is overcharged, transistor Q14 turns on, which in turn turns on MOSFET Q15, allowing discharge through resistors R23 to R27 and MOSFET Q15.

[0062] like Figure 15 As shown, the control circuit 100 also includes a protection circuit, which includes a connector CN1, a fuse F1, a capacitor C23, a diode D9, and a Zener diode D10. Pins 3 and 4 of the connector CN1 are connected to the positive terminal of the capacitor C23 and the positive terminal of the DC power supply 12 through the fuse F1. Pins 3 and 4 of the connector CN1 are also used to input an external voltage VIN. The negative terminal of the capacitor C23, the positive terminal of the diode D9, and the negative terminal of the Zener diode D10 are all connected to analog ground. The positive terminal of the Zener diode D10 is grounded, and the negative terminal of the diode D9 is connected to pins 1 and 2 of the connector. The connector CN1 is used to connect an external DC power source, which can be a DC power supply group or a power adapter connected to the mains. The input voltage range of the external DC power source is 12-18V, and the power is not less than 35W. The Schottky diode D9 can prevent the external DC power source from being reverse-connected. When a reverse connection occurs, the Schottky diode D9 conducts, pulling the potential low and protecting the subsequent circuits. When the input current is too large, the fuse F1 (4A self-resetting fuse) will trip, providing protection.

[0063] The utility model discloses a control circuit 100, the positive pole CAP of capacitor group's connection point welds the positive pole, the negative pole of capacitor group connects the source of power MOS pipe Q1~Q10, and the drain of power MOS pipe Q1~Q10 connects the negative pole of point welds. When spot welding, the positive pole and the negative pole of spot welding pen contact metal welding piece simultaneously, after the inside spot welding trigger detection module 22 detects the action, triggers spot welding: through the WELD_OUT signal output of micro control unit 11 control power MOS pipe drive module 17 carries out the short -time conduction, and then drives power MOS pipe Q1~Q10 to carry out the short -time conduction, at this moment, spot welding pen positive pole (connects the positive pole CAP of capacitor group)-welding work piece-spot welding pen negative pole-power MOS pipe Q1~Q10-capacitor group negative pole forms the circuit and carries out discharge in turn, thereby reaches the spot welding effect. When the 1 pin of photoelectric coupling chip U4 pulls high, photoelectric coupling conduction in succession, and then power MOS pipe Q1~Q10 is pulled high to 15V drive voltage, and then the drain and the source of power MOS pipe Q1~Q10 conduction, spot welding output.

[0064] The utility model further provides a spot welding machine, including the control circuit described in the above embodiment.

[0065] The principle and implementation mode of the utility model are described by applying specific examples in the paper, and the above embodiment is only used for helping to understand the method and core idea of the utility model; at the same time, for the technical personnel in the field, according to the idea of the utility model, the specific implementation mode and application range will have the change, and the above-mentioned, the content of the specification should not be understood as the limitation of the utility model.

Claims

1. A control circuit for a spot welder, characterised in that, The micro control unit, direct current power supply, charging module, capacitor module, voltage boosting module, power MOS tube module, MOS tube driving module, key module, voltage detection module, voltage reducing and stabilizing module and spot welding trigger detection module are included. The micro control unit is connected with the charging module, voltage detection module, voltage reducing and stabilizing module, key module and spot welding trigger detection module respectively, the voltage detection module is connected with the capacitor module, the direct current power supply is connected with the charging module, voltage boosting module and voltage reducing and stabilizing module respectively, the voltage boosting module is connected with the MOS tube driving module, the MOS tube driving module is connected with the power MOS tube module, the power MOS tube module is connected with the negative pole of the spot welding pen of the spot welding machine, and the capacitor module is connected with the power MOS tube module and the positive pole of the spot welding pen of the spot welding machine respectively.

2. The control circuit of claim 1, wherein, The charging self-balancing module, buzzer module, temperature sensor, display module and foot switch module are further included, the micro control unit is connected with the buzzer module, temperature sensor, display module and foot switch module respectively, the temperature sensor is connected with the power MOS tube module, and the charging self-balancing module is connected with the capacitor module.

3. The control circuit of claim 2, wherein, The micro control unit includes chip U1, resistor R41, resistor R42 and capacitor C12, the 4th pin of chip U1 is connected with working voltage VCC through resistor R42, the 31st pin of chip U1 is grounded through resistor R41, and the 5th pin of chip U1 is grounded through capacitor C12.

4. The control circuit of claim 3, wherein, The voltage reducing and stabilizing module includes chip U11, voltage stabilizing diode D5, magnetic bead L1, capacitor C2, capacitor C3 and resistor R40, the positive pole of voltage stabilizing diode D5 is connected with the positive pole of direct current power supply, the negative pole of voltage stabilizing diode D5 is connected with the 3rd pin of chip U11 through magnetic bead L1, one end of capacitor C2 is connected with the 3rd pin of chip U11, the other end is grounded, the 2nd pin and the 4th pin of chip U11 are both connected with one end of resistor R40, the other end of resistor R40 outputs working voltage VCC and is grounded through capacitor C3; The voltage boosting module includes chip U2, resistor R1, resistor R2, voltage stabilizing diode D1, voltage stabilizing diode D2, voltage stabilizing diode D3, inductor L2, capacitor C4 and capacitor C5, the 1st pin of chip U2 is connected with the positive pole of voltage stabilizing diode D2 and one end of inductor L2, the negative pole of voltage stabilizing diode D2 outputs driving voltage and is connected with one end of resistor R1 and one end of capacitor C5, the other end of resistor R1 is connected with the 3rd pin of chip U2, the other end of capacitor C5 is connected with the 2nd pin of chip U2, one end of resistor R2 is connected with the 3rd pin of chip U2, the other end of resistor R2 and the 2nd pin of chip U2 are grounded, the other end of inductor L2, one end of capacitor C4 and the negative pole of voltage stabilizing diode D1 are all connected with the 5th pin of chip U2, the other end of capacitor C4 is grounded, the positive pole of voltage stabilizing diode D1 is connected with the positive pole of direct current power supply, the negative pole of voltage stabilizing diode D3 is connected with the 4th pin of chip U2, and the positive pole is connected with the 3rd pin of chip U1.

5. The control circuit of claim 4, wherein, The power MOS module includes MOS Q1~Q10, and the MOS drive module includes resistors R12, R13, R14 and an optical coupling chip U4. The 1 pin of the optical coupling chip U4 is connected to the 2 pin of the chip U1, the 2 pin of the optical coupling chip U4 is grounded through the resistor R13, the 4 pin of the optical coupling chip U4 is connected to a driving voltage, the 3 pin of the optical coupling chip U4 is connected to one end of the resistor R14 and the gate of the MOS Q1~Q10 through the resistor R12, the other end of the resistor R14 is grounded and connected to the source of the MOS Q1~Q10, and the drain of the MOS Q1~Q10 is connected to a negative pole of a pen.

6. The control circuit of claim 3, wherein, The key module includes an encoder SW1, resistors R47, R48, R49, capacitors C14, C15, C16 and C17. The A pin of the encoder SW1 is connected to the 22 pin of the chip U1, one end of the resistor R49 and one end of the capacitor C15 are both connected to the A pin of the encoder SW1, the other end of the resistor R49 is connected to a working voltage VCC, one end of the resistor R48 is connected to the working voltage VCC, the other end of the resistor R48 is connected to the B pin of the encoder SW1, the other end of the capacitor C15 is grounded, one end of the capacitor C16 is connected to the B pin of the encoder SW1, the other end of the capacitor C16 is grounded, the B pin of the encoder SW1 is connected to the 21 pin of the chip U1, the D pin of the encoder SW1 is connected to the 30 pin of the chip U1, the D pin of the encoder SW1 is further connected to the working voltage VCC through the resistor R47 and grounded through the capacitor C14, and the E pin of the encoder SW1 is grounded.

7. The control circuit of claim 3, wherein, The capacitor module includes a capacitor group, the capacitor group includes two super-farad capacitors in series, and the voltage detection module includes resistors R36, R37, R38, R39, capacitors C7 and C8. One end of the resistor R36 is connected to the positive pole CAP+ of the capacitor group, the other end of the resistor R36 and one end of the resistor R37 and one end of the capacitor C7 are connected to the 25 pin of the chip U1, the other end of the resistor R37 and the other end of the capacitor C7 are grounded. One end of the resistor R38 is connected to the series node CAPM of the capacitor group, the other end of the resistor R38 and one end of the resistor R39 and one end of the capacitor C8 are connected to the 26 pin of the chip U1, the other end of the resistor R39 and the other end of the capacitor C8 are grounded. The foot switch module includes an optical coupling chip U14, resistors R50, R51, R52, a foot switch connecting seat DC1 and a capacitor C18. The 1 pin of the optical coupling chip U14 is connected to the working voltage VCC through the resistor R50, the 2 pin of the optical coupling chip U14 is connected to the 1 pin of the foot switch connecting seat DC1, the 3 pin of the foot switch connecting seat DC1 is grounded through the resistor R52, the 4 pin of the optical coupling chip U14 is connected to the 28 pin of the chip U1 and the working voltage VCC through the resistor R51, one end of the capacitor C18 is connected to the 4 pin of the optical coupling chip U14, and the other end of the capacitor C18 and the 3 pin of the optical coupling chip U14 are both grounded. The spot welding trigger detection module comprises a diode D4, a resistor R7 and a resistor R8, the negative electrode of the diode D4 and one end of the resistor R7 are connected to the negative electrode of the spot welding pen, the other end of the resistor R7 and one end of the resistor R8 are connected to the 8th pin of the chip U1, the positive electrode of the diode D4 and the other end of the resistor R8 are grounded.

8. The control circuit of claim 3, wherein, The charging module comprises a chip U7, a chip U8, a diode D6, a voltage stabilizing diode D7, a diode D8, resistors R61 to R67, an inductor L3, a capacitor C1 and a triode Q12; one end of the capacitor C1 is connected to the positive electrode of the direct current power supply through the 4th pin of the chip U7 and the 5th pin of the chip U8, the other end of the capacitor C1 is connected to the analog ground, the 3rd pin and the 6th pin of the chip U8 are connected to the negative electrode of the diode D8, the positive electrode of the diode D8 and one end of the resistor R65 and the 1st pin of the chip U8 are connected to the analog ground, the other end of the resistor R65 and the 4th pin of the chip U8 and one end of the resistor R64 are grounded, the other end of the resistor R64 is connected to the 2nd pin of the chip U7, one end of the resistor R61 and one end of the resistor R62 and the negative electrode of the voltage stabilizing diode D7 are connected to the 2nd pin of the chip U8, the positive electrode of the voltage stabilizing diode D7 is connected to the 3rd pin of the chip U7 through the resistor R63, the other end of the resistor R61, the positive electrode of the diode D6, one end of the capacitor C19 and one end of the inductor L3 are connected, the other end of the inductor L3 is connected to the 6th pin of the chip U8, the other end of the resistor R62 and the other end of the capacitor C19 are connected to the analog ground, the negative electrode of the diode D6 outputs the charging voltage, the 1st pin of the chip U7 is the collector of the triode Q12, one end of the resistor R67 is connected to the working voltage VCC through the emitter of the triode Q12, the other end of the resistor R67 and one end of the resistor R66 are connected to the base of the triode Q12, one end of the resistor R66 is connected to the 15th pin of the chip U1.

9. The control circuit of claim 3, wherein, The capacitor module comprises a capacitor group, the capacitor group comprises two super-farad capacitors connected in series, the charging self-balancing module comprises a chip U5, a chip U6, resistors R15 to R36, a triode Q14, a triode Q17, a MOS tube Q15 and a MOS tube Q16. One end of the resistor R15 is connected with one end of the resistor R21, one end of the resistor R23, one end of the resistor R24, one end of the resistor R25, one end of the resistor R26, one end of the resistor R27, and the emitter of the transistor Q14 to the series node CAPM of the capacitor group, the other end of the resistor R15 is connected with one end of the resistor R16 to the 1 pin of the chip U5, the other end of the resistor R16 is connected with the 3 pin of the chip U5, one end of the resistor R22, and the source of the MOS transistor Q15 to the ground, the 2 pin of the chip U5 is connected with the other end of the resistor R21 and one end of the resistor R19, the other end of the resistor R19 is connected with the base of the transistor Q14, the collector of the transistor Q14 is connected with one end of the resistor R20, the other end of the resistor R20 and the other end of the resistor R22 are connected with the gate of the MOS transistor Q15, the drain of the MOS transistor Q15 is connected with the other end of the resistor R23, the other end of the resistor R24, the other end of the resistor R25, the other end of the resistor R26, and the other end of the resistor R27; One end of the resistor R17 is connected with one end of the resistor R34, one end of the resistor R28, one end of the resistor R29, one end of the resistor R30, one end of the resistor R31, one end of the resistor R32, and the emitter of the transistor Q17 to the positive electrode CAP+ of the capacitor group, the other end of the resistor R17 is connected with one end of the resistor R18 to the 1 pin of the chip U6, the other end of the resistor R18 is connected with the 3 pin of the chip U6, one end of the resistor R35, and the source of the MOS transistor Q16 to the series node CAPM of the capacitor group, the 2 pin of the chip U6 is connected with the other end of the resistor R34 and one end of the resistor R33, the other end of the resistor R33 is connected with the base of the transistor Q17, the collector of the transistor Q17 is connected with one end of the resistor R36, the other end of the resistor R36 and the other end of the resistor R35 are connected with the gate of the MOS transistor Q16, and the drain of the MOS transistor Q16 is connected with the other end of the resistor R28, the other end of the resistor R29, the other end of the resistor R30, the other end of the resistor R31, and the other end of the resistor R32.

10. Spot welder, characterized in that The control circuit of any one of claims 1-9.

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