Multi-section intermediate frequency welding signal acquisition circuit

Abstract

The utility model provides a multi-section type intermediate frequency welding signal acquisition circuit which comprises a control module, a switching module, a first voltage acquisition module, a second voltage acquisition module and a current acquisition module, and the input end of the switching module is electrically connected with the output end of a pressure sensor and the secondary output end of a transformer. The output end of the switching module is electrically connected with the input end of the first voltage acquisition module and the input end of the second voltage acquisition module, and the first voltage acquisition module and the second voltage acquisition module are connected with the feedback output end of an external pressure sensor and the secondary output end of a transformer through the switching module. The voltage measuring module is used for respectively measuring feedback voltage of the pressure sensor and secondary voltage of the transformer, an output current value during welding can be acquired through the current acquisition module, a welding resistance value is calculated according to the acquired voltage value and current value, then the state of a welding spot and welding quality can be judged according to resistance, and the welding quality can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of medium frequency welding, in particular to a multi-stage medium frequency welding signal acquisition circuit. Background Art

[0002] The multi-stage medium frequency welding system is a device that uses a medium frequency power supply for welding. Its characteristic is that it can achieve high-precision control of the welding process by adjusting multiple currents. This system is widely used in the field of metal processing and manufacturing, especially in the automotive, home appliance, electronics and other industries.

[0003] An intelligent welding control system and method with publication number CN109202250A includes a logic control module connected to a power drive and a controller, an AC power supply connected to an input end of a full-bridge rectifier circuit, a power drive connected between the AC power supply and an inverter circuit unit, an output end of the full-bridge rectifier circuit connected to an input end of a DC circuit, an output end of the DC circuit connected to an input end of an inverter circuit unit, an output end of the inverter circuit unit connected to an input end of a medium frequency welding transformer, an output end of the medium frequency welding transformer connected to a current rectifier unit, and an output end of the current rectifier unit connected to a welding clamp device.

[0004] The welding control system in the above-mentioned prior art has poor accuracy in collecting the current and voltage output by the controller, which leads to errors in the measured voltage and current, and further leads to deviations in the calculated resistance of the welding plate, which affects the judgment of the state of the welding point and the welding quality, and reduces the welding quality. Utility Model Content

[0005] In view of this, the utility model proposes a multi-stage medium frequency welding signal acquisition circuit, which can accurately collect the voltage and current values ​​during welding in real time. Then the system can judge the state of the weld and the welding quality according to the voltage and current, which can effectively improve the welding quality.

[0006] The technical solution of the utility model is implemented as follows: The utility model provides a multi-stage intermediate frequency welding signal acquisition circuit, including a control module, a switching module, a first voltage acquisition module, a second voltage acquisition module and a current acquisition module, wherein:

[0007] The input end of the adapter module is electrically connected to the output end of the pressure sensor and the secondary output end of the transformer respectively, the output end of the adapter module is electrically connected to the input end of the first voltage acquisition module and the second voltage acquisition module respectively, the output ends of the first voltage acquisition module and the second voltage acquisition module are both electrically connected to the input end of the control module, the first voltage acquisition module is used to measure the feedback voltage signal of the pressure sensor, and the second voltage acquisition module is used to measure the secondary voltage signal of the transformer;

[0008] The output end of the current acquisition module is electrically connected to the input end of the control module, and is used to feed back the current signal during welding to the control module.

[0009] On the basis of the above technical solution, preferably, the adapter module includes an adapter P3, a varistor Z4, a varistor Z3, a varistor Z2, a varistor Z1, a resistor R126, a resistor R127, a resistor R81, a resistor R84, a resistor R61 and a resistor R58, wherein pin 1 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R81 respectively, pin 2 of the adapter P3 is electrically connected to the varistor Z3 and the resistor R84 respectively, and pin 7 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R81 respectively. They are electrically connected to the varistor Z2, the resistor R126 and the resistor R61 respectively, the pin 8 of the adapter P3 is electrically connected to the varistor Z1, the resistor R127 and the resistor R58 respectively, the other end of the resistor R126 is electrically connected to the other end of the resistor R127, the other end of the varistor Z4 is electrically connected to the other end of the varistor Z3, the other end of the varistor Z2 and the other end of the varistor Z1, and are commonly grounded with pins 5, 9, 10 and 11 of the adapter P3.

[0010] On the basis of the above technical solution, preferably, the first voltage acquisition module includes a Schott diode D15, a Schott diode D16, a resistor R79, a resistor R82, a capacitor C94, a resistor R80, a resistor R83, a chip U21, an amplifier U19A, a capacitor C88, and a resistor R78, wherein the other end of the resistor R81 is electrically connected to the third end of the Schott diode D15, the capacitor C94, the resistor R79, the resistor R80, and the pin 1 of the chip U21, respectively, the other end of the resistor R84 is electrically connected to the Schott diode D16, the resistor R82, the other end of the capacitor C94, the resistor R83 and the pin 2 of the chip U21, the second end of the Schott diode D15 is connected to the power supply, and the third end of the Schott diode D16 is connected to the power supply. The two ends are connected to the power supply, the first end of the Schott diode D15 is electrically connected to the first end of the Schott diode D16, the other end of the resistor R79 and the other end of the resistor R82, and are commonly grounded, the other end of the resistor R80 is electrically connected to the other end of the resistor 83, the inverting input end of the amplifier U19A and the output end of the amplifier U19A, the pin 3 of the chip U21 is electrically connected to the non-inverting input end of the amplifier U19A and the capacitor C88 respectively, the other end of the capacitor C88 is grounded, the pin 8 of the chip U21 is electrically connected to the resistor R78, the other end of the resistor R78 is electrically connected to the input end of the control module, the pin 10 of the chip U21 is electrically connected to the output end of the power conversion module 5, and the pin 9 of the chip U21 is electrically connected to the output end of the control module.

[0011] On the basis of the above technical solution, preferably, the circuit of the second voltage acquisition module is the same as that of the first voltage acquisition module, and the other end of the resistor R61 and the other end of the resistor R58 are both electrically connected to the input end of the second voltage acquisition module, and the output end of the second voltage acquisition module is electrically connected to the control module.

[0012] On the basis of the above technical solution, preferably, the current acquisition module includes a Rogowski coil, a buffer unit, a range selection unit, a reset unit, an amplifying unit and a conversion unit, wherein the output end of the Rogowski coil is electrically connected to the input end of the buffer unit; the reset unit is electrically connected to the range selection unit and the buffer unit respectively, the output end of the buffer unit and the output end of the range selection unit are both electrically connected to the input end of the amplifying unit, the output end of the amplifying unit is electrically connected to the input end of the conversion unit, and the output end of the conversion unit is electrically connected to the input end of the control module.

[0013] On the basis of the above technical scheme, preferably, the buffer unit includes resistor R9, resistor R10, resistor R15, resistor R16, resistor R26, resistor R27, resistor R20, resistor R21, resistor R2, resistor R1, spare resistor R1A, spare resistor R2A, resistor R24, resistor R19, resistor R14, resistor R33, resistor R37, resistor R39 and capacitor C49, wherein one end of the Rogowski coil is electrically connected to resistor R9, resistor R15, resistor R26, resistor R20, resistor R2 and resistor R9 respectively, two ends of the spare resistor R2A are electrically connected to two ends of resistor R2 respectively, and the other end of the Rogowski coil is electrically connected to resistor R10, resistor R16, resistor R27, resistor R21, resistor R1, resistor R24 ​​and resistor R14 respectively The two ends of the standby resistor R1A are electrically connected to the two ends of the resistor R1 respectively, the other end of the resistor R9 is electrically connected to the other end of the resistor R10, the other end of the resistor R15 is electrically connected to the other end of the resistor R16 and are commonly grounded, the other end of the resistor R26 is electrically connected to the other end of the resistor R27, the other end of the resistor R20 is electrically connected to the other end of the resistor R21, the other end of the resistor R19 is electrically connected to the capacitor C49 and the resistor R37 respectively, the other end of the capacitor C49 is grounded, the other end of the resistor R24 ​​is electrically connected to the resistor R39, the other end of the resistor R14 is electrically connected to the reset unit and the resistor R33 respectively, the common end of the resistor R33 and the resistor R37 is electrically connected to the range selection unit and the amplification unit respectively, and the other end of the resistor R39 is electrically connected to the amplification unit.

[0014] On the basis of the above technical scheme, preferably, the amplifying unit includes an amplifier U5A, an amplifier U6A and a capacitor C54, wherein the other end of the resistor R39 is electrically connected to the in-phase input terminal of the amplifier U5A, the common end of the resistor R33 and the resistor R37 is respectively electrically connected to one end of the range selection unit and the reverse input terminal of the amplifier U5A, the output end of the amplifier U5A is electrically connected to the forward input terminal of the amplifier U6A, the output end of the amplifier U6A is respectively electrically connected to one end of the range selection unit and the input end of the conversion unit, the reverse input terminal of the amplifier U6A is electrically connected to one end of the range selection unit, and the two ends of the capacitor C54 are respectively electrically connected to the reverse input terminal and the output terminal of the amplifier U6A.

[0015] On the basis of the above technical scheme, preferably, the range selection unit includes capacitor C1, capacitor C1A, analog switch U12C, capacitor C2, capacitor C2A, analog switch U7A, resistor R25, capacitor C3, capacitor C3A, analog switch U7C, resistor R34, capacitor C4, capacitor C4A, analog switch U7D and resistor R40, wherein one end of the capacitor C1 is electrically connected to the first end of the analog switch U12C, capacitor C1A, capacitor C2, capacitor C2A, the first end of the analog switch U7A and resistor R25, the other end of the resistor R25 is grounded, the third end of the analog switch U7A and the third end of the analog switch U12C are commonly connected to the input end of the control module, one end of the capacitor C3 is electrically connected to the first end of the analog switch U7C, capacitor C3A and resistor R34, and resistor The other end of R34 is grounded, the third end of the analog switch U7C is electrically connected to the input end of the control module, one end of the capacitor C4 is electrically connected to the first end of the analog switch U7D, the capacitor C4A, the resistor R40 and the reverse input end of the amplifier U6A, the other end of the resistor R40 is grounded, the third end of the analog switch U7D is electrically connected to the input end of the control module, the other end of the capacitor C1 is electrically connected to the other ends of the capacitors C1A, C2, C2A, C3, C3A, C4, C4A, R33 and R37, and are commonly connected to the reverse input end of the amplifier U5A, and the second end of the analog switch U12C is electrically connected to the second end of the analog switch U7A, the second end of the analog switch U7C, the second end of the analog switch U7D and the output end of the amplifier U6A.

[0016] On the basis of the above technical scheme, preferably, the reset unit includes a chip U9, a capacitor C71, a resistor R50, an amplifier U8A, a capacitor C62, an analog switch U12D, an analog switch U12A, an analog switch U12B, an analog switch U7B, a resistor R51, a MOS tube Q4, a resistor R49 and an amplifier U8B, wherein the pin 5 of the chip U9 is electrically connected to the pin 4 of the chip U9 and the capacitor C71, and is commonly grounded, the other end of the capacitor C71 is electrically connected to the pin 6 of the chip U9, the resistor R50 and the positive input end of the amplifier U8A, the other end of the resistor R50 is connected to the power supply, the reverse input end of the amplifier U8A is electrically connected to the capacitor C62, the first end of the analog switch U12D and the resistor R49, the other end of the resistor R49 is electrically connected to the output end of the amplifier U8B and the reverse input end of the amplifier U8B respectively, and the output end of the amplifier U8A is electrically connected to the reverse input end of the amplifier U8B. The analog switch U12A is electrically connected to the other end of the capacitor C62, the first end of the analog switch U12A and the second end of the analog switch U12D respectively. The second end of the analog switch U12A is electrically connected to the first end of the analog switch U12B and the first end of the analog switch U7B respectively. The second end of the analog switch U12B is electrically connected to the output end of the amplifier U6A. The second end of the analog switch U7B is electrically connected to the positive input end of the amplifier U8B, the common end of the resistor R14 and the resistor R33 respectively. The third end of the analog switch U12D is electrically connected to the third end of the analog switch U12B and is commonly connected to the output end of the control module. The third end of the analog switch U7B is electrically connected to the output end of the control module 1. The third end of the analog switch U12A is electrically connected to the resistor R51 and the drain of the MOS tube Q4 respectively. The source of the MOS tube Q4 is grounded, and the gate of the MOS tube Q4 is electrically connected to the output end of the control module.

[0017] On the basis of the above technical scheme, preferably, the conversion unit includes a chip U11, a resistor R48, a resistor R43, a capacitor C67, a capacitor C63, a Schottky diode D8, a resistor R44, a resistor R42, an amplifier U6B, a capacitor C60 and a resistor R47, wherein pin 1 of the chip U11 is electrically connected to the capacitor C63, the third end of the Schottky diode D8, the resistor R42 and the resistor R44, respectively, the other end of the resistor R44 is electrically connected to the output end of the amplifier U6A, and pin 2 of the chip U11 is electrically connected to the capacitor C67, the resistor R48 and the resistor R43, respectively, and the other end of the resistor R43 is electrically connected to the output end of the amplifier U6A. The other end of resistor R42, the output end of amplifier U6B and the reverse input end of amplifier U6B are electrically connected, the same-direction input end of amplifier U6B is electrically connected to capacitor C60 and pin 3 of chip U11 respectively, the other end of capacitor C60 is grounded, the other end of capacitor C67 is electrically connected to resistor R48, capacitor C63 and the first end of Schottky diode D8, and are commonly grounded, the second end of Schottky diode D8 is connected to the power supply, pin 8 of chip U11 is electrically connected to resistor R47, the other end of resistor R47 is electrically connected to the input end of the control module, and pins 10 and 9 of chip U11 are electrically connected to the output end of the control module.

[0018] Compared with the prior art, the multi-stage intermediate frequency welding signal acquisition circuit of the utility model has the following beneficial effects:

[0019] (1) The first voltage acquisition module and the second voltage acquisition module are respectively connected to the external pressure sensor feedback output terminal and the transformer secondary output terminal through the adapter module to respectively measure the pressure sensor feedback voltage and the transformer secondary voltage. The output current value during welding can be acquired through the current acquisition module. The welding resistance value is calculated according to the acquired voltage value and current value. Then, the state of the welding point and the welding quality can be judged according to the resistance, which can effectively improve the welding quality;

[0020] (2) The welding current is sensed by the Rogowski coil, and the current signal is input into the buffer unit. The buffer unit buffers the induced current signal output by the Rogowski coil to suppress overvoltage or overcurrent and reduce the impact on the subsequent circuit. The amplification unit amplifies the induced voltage output by the buffer unit to facilitate subsequent signal processing or analog-to-digital conversion. The range selection unit selects a suitable range to adapt to different current ranges according to different application scenarios or requirements. The reset unit resets the buffer unit to ensure its normal operation. The conversion unit converts the amplified induced voltage into a corresponding digital signal to facilitate further processing by the control module. The digital signal output by the conversion unit is received and processed or controlled accordingly as needed to achieve accurate measurement and effective control of the measured current. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a circuit block diagram of the multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0023] Figure 2 This is a circuit block diagram of a current acquisition module of a multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0024] Figure 3 This is a circuit schematic diagram of part of the control module of the multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0025] Figure 4 This is the circuit schematic diagram of another part of the control module of the multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0026] Figure 5 This is a circuit schematic diagram of a switching module of a multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0027] Figure 6 It is a circuit schematic diagram of the first voltage acquisition module and the second voltage acquisition module of the multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0028] Figure 7 It is a circuit schematic diagram of a buffer circuit of a multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0029] Figure 8 It is a circuit schematic diagram of the range selection unit and the amplification unit connection of the multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0030] Fig. 9 This is a circuit schematic diagram of a reset unit of a multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0031] Fig.10 This is a circuit schematic diagram of a conversion unit of a multi-stage intermediate frequency welding signal acquisition circuit of the utility model;

[0032] Fig.11 This is a circuit schematic diagram of a power module of a multi-stage intermediate frequency welding signal acquisition circuit of the utility model. DETAILED DESCRIPTION

[0033] The following will be combined with the implementation of the utility model to clearly and completely describe the technical solutions in the implementation of the utility model. Obviously, the described implementation is only a part of the implementation of the utility model, not all of the implementations. Based on the implementation of the utility model, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0034] like Figure 1 As shown, a multi-stage intermediate frequency welding signal acquisition circuit of the utility model includes a control module 1, an adapter module 2, a first voltage acquisition module 3, a second voltage acquisition module 4 and a current acquisition module 5, wherein the input end of the adapter module 2 is electrically connected to the output end of the pressure sensor and the secondary output end of the transformer, respectively, the output end of the adapter module 2 is electrically connected to the input end of the first voltage acquisition module 3 and the input end of the second voltage acquisition module 4, respectively, the output ends of the first voltage acquisition module 3 and the second voltage acquisition module 4 are both electrically connected to the input end of the control module 1, the first voltage acquisition module 3 is used to measure the pressure sensor feedback voltage signal, and the second voltage acquisition module 4 is used to measure the transformer secondary voltage signal; the output end of the current acquisition module 5 is electrically connected to the input end of the control module 1, and is used to feed back the current signal during welding to the control module 1.

[0035] It should be noted that the first voltage acquisition module 3 and the second voltage acquisition module 4 are respectively connected to the external pressure sensor feedback output terminal and the transformer secondary output terminal through the adapter module 2, and are used to measure the pressure sensor feedback voltage and the transformer secondary voltage respectively. The output current value during welding can be collected through the current acquisition module 5, and the welding resistance value is calculated based on the collected voltage value and current value. Then, the state of the weld and the welding quality can be judged based on the resistance, which can effectively improve the welding quality.

[0036] As a preferred implementation, the adapter module 2 in this embodiment includes an adapter P3, a varistor Z4, a varistor Z3, a varistor Z2, a varistor Z1, a resistor R126, a resistor R127, a resistor R81, a resistor R84, a resistor R61 and a resistor R58, wherein the pin 1 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R81 respectively, the pin 2 of the adapter P3 is electrically connected to the varistor Z3 and the resistor R84 respectively, and the pin 7 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R81 respectively. They are electrically connected to the varistor Z2, the resistor R126 and the resistor R61 respectively, the pin 8 of the adapter P3 is electrically connected to the varistor Z1, the resistor R127 and the resistor R58 respectively, the other end of the resistor R126 is electrically connected to the other end of the resistor R127, the other end of the varistor Z4 is electrically connected to the other end of the varistor Z3, the other end of the varistor Z2 and the other end of the varistor Z1, and are commonly grounded with pins 5, 9, 10 and 11 of the adapter P3.

[0037] It should be noted that pins 1 and 2 of the adapter P3 interface are connected to the feedback output end of the pressure sensor to measure the real-time pressure sensor feedback voltage. The positive and negative voltage of the pressure sensor feedback voltage can be automatically adapted to the voltage range of positive and negative 0-10V, which can avoid the situation where the voltage feedback is connected incorrectly. The feedback voltage signal is converted into a digital quantity through the 14-bit ADC chip of the chip U21, and the changes in the pressure sensor feedback voltage are reflected to the control module 1 in real time; pins 7 and 8 of the adapter P3 interface are connected to the secondary output end of the transformer to measure the real-time secondary voltage. The positive and negative voltage can be automatically adapted to the voltage from positive and negative 20V, which can avoid the situation where the voltage feedback is connected incorrectly. The feedback voltage signal is converted into a digital quantity through the 14-bit ADC chip of the chip U21, and the changes in the secondary voltage of the transformer are reflected to the control module 1 in real time, thereby inferring the resistance value of the solder joint to judge the quality of the solder joint.

[0038] As a preferred implementation, the first voltage acquisition module 3 in this embodiment includes a Schott diode D15, a Schott diode D16, a resistor R79, a resistor R82, a capacitor C94, a resistor R80, a resistor R83, a chip U21, an amplifier U19A, a capacitor C88, and a resistor R78, wherein the other end of the resistor R81 is electrically connected to the third end of the Schott diode D15, the capacitor C94, the resistor R79, the resistor R80, and the pin 1 of the chip U21, respectively, the other end of the resistor R84 is electrically connected to the Schott diode D16, the resistor R82, the other end of the capacitor C94, the resistor R83, and the pin 2 of the chip U21, the second end of the Schott diode D15 is connected to the power supply, and the second end of the Schott diode D16 is connected to the power supply. The first end of the Schott diode D15 is electrically connected to the first end of the Schott diode D16, the other end of the resistor R79 and the other end of the resistor R82, and are commonly grounded. The other end of the resistor R80 is electrically connected to the other end of the resistor 83, the inverting input end of the amplifier U19A and the output end of the amplifier U19A. The pin 3 of the chip U21 is electrically connected to the non-inverting input end of the amplifier U19A and the capacitor C88 respectively. The other end of the capacitor C88 is grounded. The pin 8 of the chip U21 is electrically connected to the resistor R78. The other end of the resistor R78 is electrically connected to the input end of the control module 1. The pin 10 of the chip U21 is electrically connected to the output end of the power conversion module 5. The pin 9 of the chip U21 is electrically connected to the output end of the control module 1.

[0039] Specifically, the model of the chip U21 in this embodiment is LTC1403-1.

[0040] It should be noted that the resistors R81 and R84, the resistors R79 and R82 connected to the first voltage acquisition module 3 can be used as a voltage divider circuit to make the voltage signal input to the chip U21 positive and negative 10.625V, satisfying its input voltage range of 2.7V-3.6V. At the same time, negative voltage can be input to meet the pressure sensors of various output standards. At the same time, capacitor C94, Schott diode D15 and Schott diode D16 filter and protect the input signal to avoid sudden large voltage affecting chip U21. Capacitor C88 filters the VREF reference voltage to ensure the accuracy of the reference power supply.

[0041] The resistance of the resistor R81 and the resistor R84 is 7.5K.

[0042] As a preferred implementation, the second voltage acquisition module 4 in this embodiment has the same circuit as the first voltage acquisition module 3, and the other end of the resistor R61 and the other end of the resistor R58 are both electrically connected to the input end of the second voltage acquisition module 4, and the output end of the second voltage acquisition module 4 is electrically connected to the control module 1.

[0043] It should be noted that the resistor R61 and the resistor R58 connected to the second voltage acquisition module 4 can be used as a voltage divider circuit, so that the voltage signal input to the corresponding chip U21 is positive and negative 20V, satisfying its 2.7V-3.6V input voltage range. At the same time, negative voltage can be input to meet the specifications of various transformer output voltages.

[0044] The resistance values ​​of the resistor R61 and the resistor R58 are both 15K.

[0045] As a preferred implementation, the current acquisition module 5 in this embodiment includes a Rogowski coil, a buffer unit, a range selection unit, a reset unit, an amplifying unit and a conversion unit, wherein the output end of the Rogowski coil is electrically connected to the input end of the buffer unit; the reset unit is electrically connected to the range selection unit and the buffer unit respectively, the output end of the buffer unit and the output end of the range selection unit are both electrically connected to the input end of the amplifying unit, the output end of the amplifying unit is electrically connected to the input end of the conversion unit, and the output end of the conversion unit is electrically connected to the input end of the control module 1.

[0046] It should be noted that the welding current is induced by the Rogowski coil, and the current signal is input into the buffer unit. The buffer unit buffers the induced current signal output by the Rogowski coil to suppress overvoltage or overcurrent and reduce the impact on subsequent circuits. The amplification unit amplifies the induced voltage output by the buffer unit to facilitate subsequent signal processing or analog-to-digital conversion. The range selection unit selects a suitable range to adapt to different current ranges according to different application scenarios or requirements. The reset unit resets the buffer unit to ensure its normal operation. The conversion unit converts the amplified induced voltage into a corresponding digital signal to facilitate further processing by the control module 1. The digital signal output by the conversion unit is received, and corresponding processing or control is performed as needed to achieve accurate measurement and effective control of the measured current.

[0047] As a preferred implementation, the buffer unit in this embodiment includes a resistor R9, a resistor R10, a resistor R15, a resistor R16, a resistor R26, a resistor R27, a resistor R20, a resistor R21, a resistor R2, a resistor R1, a spare resistor R1A, a spare resistor R2A, a resistor R24, a resistor R19, a resistor R14, a resistor R33, a resistor R37, a resistor R39 and a capacitor C49, wherein one end of the Rogowski coil is electrically connected to the resistor R9, the resistor R15, the resistor R26, the resistor R20, the resistor R2 and the resistor R9, respectively, the two ends of the spare resistor R2A are electrically connected to the two ends of the resistor R2, and the other end of the Rogowski coil is electrically connected to the resistor R10, the resistor R16, the resistor R27, the resistor R21, the resistor R1, the resistor R24 ​​and the resistor R14, respectively. The two ends of the standby resistor R1A are electrically connected to the two ends of the resistor R1 respectively, the other end of the resistor R9 is electrically connected to the other end of the resistor R10, the other end of the resistor R15 is electrically connected to the other end of the resistor R16 and are commonly grounded, the other end of the resistor R26 is electrically connected to the other end of the resistor R27, the other end of the resistor R20 is electrically connected to the other end of the resistor R21, the other end of the resistor R19 is electrically connected to the capacitor C49 and the resistor R37 respectively, the other end of the capacitor C49 is grounded, the other end of the resistor R24 ​​is electrically connected to the resistor R39, the other end of the resistor R14 is electrically connected to the reset unit and the resistor R33 respectively, the common end of the resistor R33 and the resistor R37 is electrically connected to the range selection unit and the amplification unit respectively, and the other end of the resistor R39 is electrically connected to the amplification unit.

[0048] It should be noted that the induced current signal output by the Rogowski coil is buffered by the buffer unit to suppress overvoltage or overcurrent and reduce the impact on subsequent circuits. The backup resistors R1A and R2A are respectively connected in parallel with the resistors R2 and R1 to play the role of current shunting and current limiting. In the parallel circuit, the current will be distributed according to the size of the resistance. Therefore, the backup resistors can share part of the current, reduce the burden of the main resistor, and prevent the main resistor from being overloaded and burned. At the same time, the presence of the backup resistors can also play a role of current limiting, limit the current in the circuit, and protect other components in the circuit from being burned.

[0049] As a preferred implementation, the amplification unit in this embodiment includes an amplifier U5A, an amplifier U6A and a capacitor C54, wherein the other end of the resistor R39 is electrically connected to the in-phase input terminal of the amplifier U5A, the common end of the resistor R33 and the resistor R37 is electrically connected to one end of the range selection unit and the reverse input terminal of the amplifier U5A, respectively, the output end of the amplifier U5A is electrically connected to the forward input terminal of the amplifier U6A, the output end of the amplifier U6A is electrically connected to one end of the range selection unit and the input end of the conversion unit, respectively, the reverse input terminal of the amplifier U6A is electrically connected to one end of the range selection unit, and the two ends of the capacitor C54 are electrically connected to the reverse input terminal and the output terminal of the amplifier U6A, respectively.

[0050] As a preferred implementation, the range selection unit in this embodiment includes capacitor C1, capacitor C1A, analog switch U12C, capacitor C2, capacitor C2A, analog switch U7A, resistor R25, capacitor C3, capacitor C3A, analog switch U7C, resistor R34, capacitor C4, capacitor C4A, analog switch U7D and resistor R40, wherein one end of the capacitor C1 is electrically connected to the first end of the analog switch U12C, capacitor C1A, capacitor C2, capacitor C2A, the first end of the analog switch U7A and resistor R25, the other end of the resistor R25 is grounded, the third end of the analog switch U7A and the third end of the analog switch U12C are commonly connected to the input end of the control module 1, one end of the capacitor C3 is electrically connected to the first end of the analog switch U7C, capacitor C3A and resistor R34, and resistor The other end of R34 is grounded, the third end of the analog switch U7C is electrically connected to the input end of the control module 1, one end of the capacitor C4 is electrically connected to the first end of the analog switch U7D, the capacitor C4A, the resistor R40 and the reverse input end of the amplifier U6A, the other end of the resistor R40 is grounded, the third end of the analog switch U7D is electrically connected to the input end of the control module 1, the other end of the capacitor C1 is electrically connected to the other ends of the capacitors C1A, C2, C2A, C3, C3A, C4, C4A, R33 and R37, and are commonly connected to the reverse input end of the amplifier U5A, and the second end of the analog switch U12C is electrically connected to the second end of the analog switch U7A, the second end of the analog switch U7C, the second end of the analog switch U7D and the output end of the amplifier U6A.

[0051] As a preferred implementation, the reset unit in this embodiment includes a chip U9, a capacitor C71, a resistor R50, an amplifier U8A, a capacitor C62, an analog switch U12D, an analog switch U12A, an analog switch U12B, an analog switch U7B, a resistor R51, a MOS tube Q4, a resistor R49 and an amplifier U8B, wherein pin 5 of chip U9 is electrically connected to pin 4 of chip U9 and capacitor C71, and is commonly grounded, the other end of capacitor C71 is electrically connected to pin 6 of chip U9, resistor R50 and the positive input end of amplifier U8A, the other end of resistor R50 is connected to a power supply, the reverse input end of amplifier U8A is electrically connected to capacitor C62, the first end of analog switch U12D and resistor R49, the other end of resistor R49 is electrically connected to the output end of amplifier U8B and the reverse input end of amplifier U8B respectively, and the output end of amplifier U8A is electrically connected to the reverse input end of amplifier U8B respectively. The analog switch U12A is electrically connected to the other end of the capacitor C62, the first end of the analog switch U12A and the second end of the analog switch U12D. The second end of the analog switch U12A is electrically connected to the first end of the analog switch U12B and the first end of the analog switch U7B respectively. The second end of the analog switch U12B is electrically connected to the output end of the amplifier U6A. The second end of the analog switch U7B is electrically connected to the positive input end of the amplifier U8B, the common end of the resistor R14 and the resistor R33 respectively. The third end of the analog switch U12D is electrically connected to the third end of the analog switch U12B and is commonly connected to the output end of the control module 1. The third end of the analog switch U7B is electrically connected to the output end of the control module 1. The third end of the analog switch U12A is electrically connected to the resistor R51 and the drain of the MOS tube Q4 respectively. The source of the MOS tube Q4 is grounded, and the gate of the MOS tube Q4 is electrically connected to the output end of the control module 1.

[0052] It should be noted that the reset signal sent to the range selection unit is used to return the range selection unit to an initial state or a specific state. When the range selection unit receives the reset signal, it resets the internal state register or control logic to the initial state. In this way, the range selection unit can restart a new working cycle or enter a new working mode.

[0053] Specifically, the model of the chip U9 in this embodiment is LT1634-1.25.

[0054] As a preferred implementation, the conversion unit in this embodiment includes a chip U11, a resistor R48, a resistor R43, a capacitor C67, a capacitor C63, a Schottky diode D8, a resistor R44, a resistor R42, an amplifier U6B, a capacitor C60 and a resistor R47, wherein the pin 1 of the chip U11 is electrically connected to the capacitor C63, the third end of the Schottky diode D8, the resistor R42 and the resistor R44, respectively, the other end of the resistor R44 is electrically connected to the output end of the amplifier U6A, the pin 2 of the chip U11 is electrically connected to the capacitor C67, the resistor R48 and the resistor R43, respectively, the other end of the resistor R43 is electrically connected to the resistor C60, respectively. The other end of R42, the output end of amplifier U6B and the reverse input end of amplifier U6B are electrically connected, the same-direction input end of amplifier U6B is electrically connected to capacitor C60 and pin 3 of chip U11 respectively, the other end of capacitor C60 is grounded, the other end of capacitor C67 is electrically connected to resistor R48, capacitor C63 and the first end of Schottky diode D8, and are commonly grounded, the second end of Schottky diode D8 is connected to the power supply, pin 8 of chip U11 is electrically connected to resistor R47, the other end of resistor R47 is electrically connected to the input end of control module 1, and pins 10 and 9 of chip U11 are electrically connected to the output end of control module 1.

[0055] It should be noted that the amplified induced current signal is converted into a corresponding digital signal through the chip U11, so as to facilitate further processing or control by the control module 1.

[0056] Specifically, the signal of the chip U11 in this embodiment is LTC1403-1.

[0057] In this embodiment, the input end of the power conversion module is electrically connected to the external power supply, and the output end of the power conversion module is electrically connected to the input ends of the first voltage acquisition module (3) and the second voltage acquisition module (4), respectively, for supplying power to the first voltage acquisition module (3) and the second voltage acquisition module (4).

[0058] The power conversion module in this embodiment includes a resistor R77, a capacitor C82, a resistor R75, a chip U20, a capacitor C83, and a capacitor C84, wherein pin 1 of the chip U20 is electrically connected to the resistor R75, the resistor R77, and the capacitor C82, respectively, the other end of the resistor R75 is electrically connected to pin 3 of the chip U20, the other end of the capacitor C82 is grounded, the other end of the resistor R77 is connected to a power supply, pin 5 of the chip U20 is electrically connected to the capacitor C83, the capacitor C84, and the output end of the power conversion module (5), the other end of the capacitor C83 is electrically connected to pin 4 of the chip U20, and the other end of the capacitor C84 is grounded.

[0059] Specifically, the model of the chip U20 in this embodiment is LT1761-3.3.

[0060] Working principle:

[0061] The second voltage acquisition module 4 is connected to the secondary output terminal of the transformer through the adapter module 2, and is used to measure the secondary voltage of the transformer respectively. The output current value during welding is collected through the current acquisition module 5, and the welding resistance value is calculated according to the collected voltage and current values. Then, the state of the welding point and the welding quality can be judged according to the resistance.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-stage intermediate frequency welding signal acquisition circuit, characterized in that: It comprises a control module (1), a switching module (2), a first voltage acquisition module (3), a second voltage acquisition module (4) and a current acquisition module (5), wherein: The input end of the adapter module (2) is electrically connected to the output end of the pressure sensor and the secondary output end of the transformer respectively, the output end of the adapter module (2) is electrically connected to the input ends of the first voltage acquisition module (3) and the second voltage acquisition module (4) respectively, the output ends of the first voltage acquisition module (3) and the second voltage acquisition module (4) are both electrically connected to the input end of the control module (1), the first voltage acquisition module (3) is used to measure the pressure sensor feedback voltage signal, and the second voltage acquisition module (4) is used to measure the transformer secondary voltage signal; The output end of the current acquisition module (5) is electrically connected to the input end of the control module (1) and is used to feed back the current signal during welding to the control module (1).

2. The multi-stage intermediate frequency welding signal acquisition circuit according to claim 1, characterized in that: The adapter module (2) comprises an adapter P3, a varistor Z4, a varistor Z3, a varistor Z2, a varistor Z1, a resistor R126, a resistor R127, a resistor R81, a resistor R84, a resistor R61 and a resistor R58, wherein the pin 1 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R81 respectively, the pin 2 of the adapter P3 is electrically connected to the varistor Z3 and the resistor R84 respectively, the pin 7 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R84 respectively, and the pin 8 of the adapter P3 is electrically connected to the varistor Z4 and the resistor R84 respectively. Z2, resistor R126 and resistor R61 are electrically connected, pin 8 of adapter P3 is electrically connected to varistor Z1, resistor R127 and resistor R58 respectively, the other end of resistor R126 is electrically connected to the other end of resistor R127, the other end of varistor Z4 is electrically connected to the other end of varistor Z3, the other end of varistor Z2 and the other end of varistor Z1, and is commonly grounded with pin 5, pin 9, pin 10 and pin 11 of adapter P3.

3. The multi-stage intermediate frequency welding signal acquisition circuit as described in claim 2 is characterized in that: The first voltage acquisition module (3) comprises a Schott diode D15, a Schott diode D16, a resistor R79, a resistor R82, a capacitor C94, a resistor R80, a resistor R83, a chip U21, an amplifier U19A, a capacitor C88, and a resistor R78, wherein the other end of the resistor R81 is electrically connected to the third end of the Schott diode D15, the capacitor C94, the resistor R79, the resistor R80, and a pin 1 of the chip U21, respectively; the other end of the resistor R84 is electrically connected to the Schott diode D16, the resistor R82, the other end of the capacitor C94, the resistor R83, and a pin 2 of the chip U21, respectively; the second end of the Schott diode D15 is connected to a power supply, the second end of the Schott diode D16 is connected to a power supply, and the The first end of the diode D15 is electrically connected to the first end of the Schott diode D16, the other end of the resistor R79 and the other end of the resistor R82, and are commonly grounded. The other end of the resistor R80 is electrically connected to the other end of the resistor 83, the inverting input end of the amplifier U19A and the output end of the amplifier U19A. The pin 3 of the chip U21 is electrically connected to the non-inverting input end of the amplifier U19A and the capacitor C88 respectively. The other end of the capacitor C88 is grounded. The pin 8 of the chip U21 is electrically connected to the resistor R78. The other end of the resistor R78 is electrically connected to the input end of the control module (1). The pin 10 of the chip U21 is electrically connected to the output end of the power conversion module (5). The pin 9 of the chip U21 is electrically connected to the output end of the control module (1).

4. The multi-stage intermediate frequency welding signal acquisition circuit as described in claim 3 is characterized in that: The circuit of the second voltage acquisition module (4) is the same as that of the first voltage acquisition module (3), and the other end of the resistor R61 and the other end of the resistor R58 are both electrically connected to the input end of the second voltage acquisition module (4), and the output end of the second voltage acquisition module (4) is electrically connected to the control module (1).

5. The multi-stage intermediate frequency welding signal acquisition circuit according to claim 1, characterized in that: The current acquisition module (5) comprises a Rogowski coil, a buffer unit, a range selection unit, a reset unit, an amplifying unit and a conversion unit, wherein the output end of the Rogowski coil is electrically connected to the input end of the buffer unit; the reset unit is electrically connected to the range selection unit and the buffer unit respectively; the output end of the buffer unit and the output end of the range selection unit are both electrically connected to the input end of the amplifying unit; the output end of the amplifying unit is electrically connected to the input end of the conversion unit; and the output end of the conversion unit is electrically connected to the input end of the control module (1).

6. The multi-stage intermediate frequency welding signal acquisition circuit as claimed in claim 5, characterized in that: The buffer unit includes a resistor R9, a resistor R10, a resistor R15, a resistor R16, a resistor R26, a resistor R27, a resistor R20, a resistor R21, a resistor R2, a resistor R1, a spare resistor R1A, a spare resistor R2A, a resistor R24, a resistor R19, a resistor R14, a resistor R33, a resistor R37, a resistor R39 and a capacitor C49, wherein one end of the Rogowski coil is electrically connected to the resistor R9, the resistor R15, the resistor R26, the resistor R20, the resistor R2 and the resistor R9 respectively, two ends of the spare resistor R2A are electrically connected to two ends of the resistor R2 respectively, the other end of the Rogowski coil is electrically connected to the resistor R10, the resistor R16, the resistor R27, the resistor R21, the resistor R1, the resistor R24 ​​and the resistor R14 respectively, and the spare resistor R Two ends of 1A are electrically connected to two ends of resistor R1 respectively, the other end of resistor R9 is electrically connected to the other end of resistor R10, the other end of resistor R15 is electrically connected to the other end of resistor R16 and is commonly grounded, the other end of resistor R26 is electrically connected to the other end of resistor R27, the other end of resistor R20 is electrically connected to the other end of resistor R21, the other end of resistor R19 is electrically connected to capacitor C49 and resistor R37 respectively, the other end of capacitor C49 is grounded, the other end of resistor R24 ​​is electrically connected to resistor R39, the other end of resistor R14 is electrically connected to the reset unit and resistor R33 respectively, the common end of resistor R33 and resistor R37 is electrically connected to the range selection unit and the amplification unit respectively, and the other end of resistor R39 is electrically connected to the amplification unit.

7. The multi-stage intermediate frequency welding signal acquisition circuit as claimed in claim 6, characterized in that: The amplification unit includes an amplifier U5A, an amplifier U6A and a capacitor C54, wherein the other end of the resistor R39 is electrically connected to the in-phase input terminal of the amplifier U5A, the common end of the resistor R33 and the resistor R37 is electrically connected to one end of the range selection unit and the reverse input terminal of the amplifier U5A respectively, the output end of the amplifier U5A is electrically connected to the forward input terminal of the amplifier U6A, the output end of the amplifier U6A is electrically connected to one end of the range selection unit and the input end of the conversion unit respectively, the reverse input terminal of the amplifier U6A is electrically connected to one end of the range selection unit, and the two ends of the capacitor C54 are electrically connected to the reverse input terminal and the output terminal of the amplifier U6A respectively.

8. The multi-stage intermediate frequency welding signal acquisition circuit as claimed in claim 7, characterized in that: The range selection unit comprises a capacitor C1, a capacitor C1A, an analog switch U12C, a capacitor C2, a capacitor C2A, an analog switch U7A, a resistor R25, a capacitor C3, a capacitor C3A, an analog switch U7C, a resistor R34, a capacitor C4, a capacitor C4A, an analog switch U7D and a resistor R40, wherein one end of the capacitor C1 is electrically connected to the first end of the analog switch U12C, the capacitor C1A, the capacitor C2, the capacitor C2A, the first end of the analog switch U7A and the resistor R25, the other end of the resistor R25 is grounded, the third end of the analog switch U7A and the third end of the analog switch U12C are connected to the input end of the control module (1), one end of the capacitor C3 is electrically connected to the first end of the analog switch U7C, the capacitor C3A and the resistor R34, the other end of the resistor R34 is grounded , the third end of the analog switch U7C is electrically connected to the input end of the control module (1), one end of the capacitor C4 is electrically connected to the first end of the analog switch U7D, the capacitor C4A, the resistor R40 and the reverse input end of the amplifier U6A, the other end of the resistor R40 is grounded, the third end of the analog switch U7D is electrically connected to the input end of the control module (1), the other end of the capacitor C1 is electrically connected to the other ends of the capacitors C1A, C2, C2A, C3, C3A, C4, C4A, the resistor R33 and R37, and are commonly connected to the reverse input end of the amplifier U5A, and the second end of the analog switch U12C is electrically connected to the second end of the analog switch U7A, the second end of the analog switch U7C, the second end of the analog switch U7D and the output end of the amplifier U6A.

9. The multi-stage intermediate frequency welding signal acquisition circuit as claimed in claim 8, characterized in that: The reset unit includes a chip U9, a capacitor C71, a resistor R50, an amplifier U8A, a capacitor C62, an analog switch U12D, an analog switch U12A, an analog switch U12B, an analog switch U7B, a resistor R51, a MOS tube Q4, a resistor R49 and an amplifier U8B, wherein pin 5 of chip U9 is electrically connected to pin 4 of chip U9 and capacitor C71, and is commonly grounded, the other end of capacitor C71 is electrically connected to pin 6 of chip U9, resistor R50 and a positive input end of amplifier U8A, the other end of resistor R50 is connected to a power supply, the reverse input end of amplifier U8A is electrically connected to capacitor C62, a first end of analog switch U12D and resistor R49, the other end of resistor R49 is electrically connected to the output end of amplifier U8B and the reverse input end of amplifier U8B respectively, the output end of amplifier U8A is electrically connected to the other end of capacitor C62, The first end of the analog switch U12A is electrically connected to the second end of the analog switch U12D, the second end of the analog switch U12A is electrically connected to the first end of the analog switch U12B and the first end of the analog switch U7B respectively, the second end of the analog switch U12B is electrically connected to the output end of the amplifier U6A, the second end of the analog switch U7B is electrically connected to the positive input end of the amplifier U8B, the common end of the resistor R14 and the resistor R33 respectively, the third end of the analog switch U12D is electrically connected to the third end of the analog switch U12B and is commonly connected to the output end of the control module (1), the third end of the analog switch U7B is electrically connected to the output end of the control module (1), the third end of the analog switch U12A is electrically connected to the resistor R51 and the drain of the MOS tube Q4 respectively, the source of the MOS tube Q4 is grounded, and the gate of the MOS tube Q4 is electrically connected to the output end of the control module (1).

10. The multi-stage intermediate frequency welding signal acquisition circuit according to claim 9, characterized in that: The conversion unit includes a chip U11, a resistor R48, a resistor R43, a capacitor C67, a capacitor C63, a Schottky diode D8, a resistor R44, a resistor R42, an amplifier U6B, a capacitor C60 and a resistor R47, wherein a pin 1 of the chip U11 is electrically connected to the capacitor C63, the third end of the Schottky diode D8, the resistor R42 and the resistor R44 respectively, the other end of the resistor R44 is electrically connected to the output end of the amplifier U6A, a pin 2 of the chip U11 is electrically connected to the capacitor C67, the resistor R48 and the resistor R43 respectively, the other end of the resistor R43 is electrically connected to the other end of the resistor R42, the amplifier U6A respectively, and the output end of the amplifier U6A respectively. The output end of the amplifier U6B is electrically connected to the reverse input end of the amplifier U6B, the non-inverting input end of the amplifier U6B is electrically connected to the capacitor C60 and the pin 3 of the chip U11 respectively, the other end of the capacitor C60 is grounded, the other end of the capacitor C67 is electrically connected to the resistor R48, the capacitor C63 and the first end of the Schottky diode D8, and are commonly grounded, the second end of the Schottky diode D8 is connected to the power supply, the pin 8 of the chip U11 is electrically connected to the resistor R47, the other end of the resistor R47 is electrically connected to the input end of the control module (1), and the pins 10 and 9 of the chip U11 are electrically connected to the output end of the control module (1).

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