CN210789615U

CN210789615U - LLC-based double-wire pulse MIG welding power supply system

Info

Publication number: CN210789615U
Application number: CN201921150693.7U
Authority: CN
Inventors: 吴开源; 詹家通; 谢沛民; 曹宣伟; 尹彤
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2019-07-22
Filing date: 2019-07-22
Publication date: 2020-06-19
Anticipated expiration: 2029-07-22

Abstract

The utility model discloses a double-wire pulse MIG welding power supply system based on LLC, the system comprises a three-phase AC input power grid, a host power module, a slave power module, a human-computer interface module and an arc load; the arc loads comprise a master arc load and a slave arc load; the master power supply module and the slave power supply module are both connected with a three-phase alternating current input power grid; the main machine power supply module and the slave machine power supply module are respectively connected with a main machine electric arc load and a slave machine electric arc load; the human-computer interface module is connected with the host power supply module and the slave power supply module through a CAN bus; the host power supply module and the slave power supply module have the same structure and are formed by connecting N subsystems in parallel. The system combines the advantages of high welding efficiency of double-wire pulse MIG welding and high electric energy conversion efficiency of the LLC resonant converter, realizes output switching of three phase pulse waveforms, effectively improves welding quality and welding efficiency, and saves electric energy.

Description

LLC-based double-wire pulse MIG welding power supply system

Technical Field

The utility model relates to the field of welding technique, in particular to high-efficient welding technique field of double-wire pulse, concretely relates to double-wire pulse MIG welds electrical power generating system based on LLC.

Background

Since the innovation, the industry of China enters a rapid development period, and the welding technology plays an irreplaceable role in the automobile, railway, shipbuilding and petrochemical industries. The traditional single wire welding technology has low efficiency and serious energy consumption, and welding defects such as undercut, hump and the like easily occur in a welding seam. In order to comply with the development of the times, a welding technology with higher efficiency and better welding quality is produced. Compared with the single-wire pulse MIG welding, the double-wire pulse MIG welding not only improves the total heat input and welding speed, but also can change the heat distribution of welding and improve the welding quality of weldments, thereby realizing high-efficiency and high-quality welding. At present, the double-wire pulse MIG welding technology is widely applied to various production occasions, and contributes to great force for industrial development of China.

Although current double-filament pulse MIG welds and can improve welding efficiency, adopt traditional hard switch or the soft switch control technique of full-bridge of phase-shifting, electric energy conversion efficiency is low, and energy loss is serious, and it has following problem:

1. in the process of turning on and turning off the power devices of the hard switching circuit, a part of voltage and current are overlapped together, so that switching loss is caused, the efficiency is low, and electromagnetic pollution is caused.

2. The phase-shifted full-bridge soft switching circuit uses phase-shifted control at the switching-on stage of a switching tube, leads the current to lag voltage, and can realize zero-voltage switching-on of the power switching tube, but a bridge arm with light load and time lag is difficult to realize soft switching; the secondary side rectifier diode can not realize zero current turn-off, so that switching loss is caused, the problem of reverse recovery exists, ringing voltage spikes are difficult to process, and the reliability of the whole machine is deteriorated, so that the secondary side rectifier diode needs to be externally connected with a buffer absorption circuit; when the load is heavy, the duty ratio of the secondary side is lost more seriously, so that the energy of the power supply is not fully utilized, and the voltage ringing is further aggravated.

The LLC resonant converter has zero-voltage switching-on of a primary side MOSFET power switching tube, can realize zero-current switching-off and low-voltage-withstanding requirements of a secondary side rectifier diode, overcomes reverse recovery loss due to zero-current switching-off of the secondary side rectifier diode, generates small electromagnetic interference, easily solves the problems of conduction and radiation, and has the advantages of better power-down maintenance time characteristic, low loss and higher conversion efficiency.

When the LLC resonant converter operating frequency range is in f_m<f_s≤f_rIn the process, the zero-voltage switching-on of the primary side MOSFET power switch tube can be realized, the zero-current switching-off of the secondary side rectifier diode can be realized, the switching loss of the primary side power device and the secondary side power device is obviously reduced, the electric energy conversion efficiency is improved, the electromagnetic interference is smaller, and therefore the working frequency is ensured to be f_m<f_s≤f_rIn this range, the soft switching of the power device can be fully realized, thereby achieving the effect of energy saving.

The LLC resonant converter adopts a power switch tube which is an MOSFET field effect tube, and due to the limitation of the capacity of a semiconductor power device and the restriction of a magnetic material of a high-frequency transformer, the output current of a single subsystem is small and is not enough to meet the high current required by efficient welding, a plurality of subsystems are required to be connected in parallel to realize high current output, and each subsystem equally divides the high current required to be output. If each subsystem in parallel is made to operate at f_m<f_s≤f_rThis frequency rangeIn the enclosure, each subsystem is fully loaded with output, and the advantages of high efficiency and small electromagnetic interference of the LLC resonant converter can be fully exerted.

In order to further improve the welding deposition rate, improve the welding quality, improve the electric energy conversion efficiency and practice the idea of green environmental protection, a double-wire pulse MIG welding power supply system based on LLC is an effective method, and the system combines the advantages of high welding deposition efficiency of double-wire pulse MIG welding and high electric energy conversion efficiency of an LLC resonant converter, effectively improves the welding deposition rate, improves the welding quality and saves energy.

SUMMERY OF THE UTILITY MODEL

In order to overcome the shortcoming of current welding electrical power generating system, the utility model provides a two silk pulse MIG weld electrical power generating system based on LLC.

The utility model discloses at least, one of following technical scheme realizes.

A double-wire pulse MIG welding power supply system based on LLC comprises a three-phase AC input power grid, a host power supply module, a slave power supply module, a human-computer interface module and an arc load; the arc loads comprise a master arc load and a slave arc load; the master power supply module and the slave power supply module are both connected with a three-phase alternating current input power grid; the main machine power supply module and the slave machine power supply module are respectively connected with a main machine electric arc load and a slave machine electric arc load; the human-computer interface module is connected with the host power supply module and the slave power supply module through a CAN bus, so that the welding parameter setting, the double-wire pulse phase control, the welding process control and the real-time display of the welding parameters of the host power supply module and the slave power supply module are realized;

the host power supply module and the slave power supply module have the same structure and are formed by connecting N subsystems in parallel;

the subsystem comprises a main circuit, a high-frequency driving module, a DSP control module, a fault protection module and a voltage and current detection module, wherein the DSP control module is connected with the fault protection module, the high-frequency driving module and the voltage and current detection module;

the main circuit comprises an input rectifying and filtering module, an inversion module, an LLC resonance module, a power transformer and an output rectifying and filtering module which are sequentially connected, wherein one end of the input rectifying and filtering module is connected with a three-phase alternating current input power grid, and the other end of the input rectifying and filtering module is connected with the inversion module; the inversion module is connected with the LLC resonance module; one end of the power transformer is connected with the LLC resonance module, and the other end of the power transformer is connected with the output rectifying and filtering module; the output rectifying and filtering module is connected with the arc load;

the DSP control module is connected with the human-computer interface module, the human-computer interface module comprises an ARM chip, a controller, a driver and an LCD screen, wherein one end of the driver is connected with the ARM chip, and the other end of the driver is connected with the LCD screen; one end of the controller is connected with the ARM chip, and the other end of the controller is connected with the LCD screen.

Furthermore, the inverter module mainly comprises four power switch tubes, namely a first power switch tube V₁A second power switch tube V₂And a third power switch tube V₃And a fourth power switch tube V₄The D pole of the first power switch tube is connected with the input rectification filter module, the S pole of the first power switch tube is connected with the D pole of the third power switch tube, and the G pole of the first power switch tube is connected with the high-frequency driving module; the D pole of the second power switch tube is connected with the input rectification filter module, the S pole of the second power switch tube is connected with the D pole of the fourth power switch tube, and the G pole of the second power switch tube is connected with the high-frequency driving module; the D pole of the third power switch tube is connected with the S pole of the first power switch tube, the S pole of the third power switch tube is connected with the input rectification filter module, and the G pole of the third power switch tube is connected with the high-frequency driving module; and the D pole of the fourth power switch tube is connected with the S pole of the second power switch tube, the S pole of the fourth power switch tube is connected with the input rectification filter module, and the G pole of the fourth power switch tube is connected with the high-frequency driving module.

Furthermore, the LLC resonance module is mainly composed of a resonance inductor L_rAnd an excitation inductor L_mAnd a resonant capacitor C_rComposition is carried out; the resonant capacitorC_rOne end of the first power switch tube is connected with the S pole of the first power switch tube, and the other end of the first power switch tube is connected with the resonant inductor C_rConnection, said excitation inductance L_mConnected in parallel with the power transformer, and having one end connected with the resonance inductor L_rThe other end of the third power switch tube is connected with the D pole of the fourth power switch tube; the resonance inductor L_rAnd an excitation inductor L_mResonant capacitor C_rAnd the equivalent load form a resonant cavity; the equivalent load mainly comprises a power converter module, an output rectifying and filtering module and an arc load.

Further, the output rectifying and filtering module comprises a first rectifying diode D₁A second rectifying diode D₂And a second capacitor C₂(ii) a The first rectifying diode D₁And a second rectifying diode D₂Is connected with the second capacitor C₂Anode connection, the first rectifier diode D₁Is connected with the power transformer, and the second rectifying diode D₂The anode of the second capacitor C is connected with the other end of the power transformer₂The negative electrode is connected to ground.

Furthermore, the fault protection module comprises an overvoltage detection module, an undervoltage detection module, an overcurrent detection module, an overtemperature detection module and a gate circuit. The overvoltage detection module and the undervoltage detection module are connected with a three-phase alternating current input power grid, the overcurrent detection module is connected with the power transformer, the over-temperature detection module is connected with the radiator, and the overvoltage detection module, the undervoltage detection module, the overcurrent detection module and the over-temperature detection module are all connected with a gate circuit.

Furthermore, the primary side of the high-frequency driving module adopts a totem-pole type pushing structure to realize rapid switching and increase power of driving signals sent by the DSP control module, and the secondary side adopts a voltage-stabilizing tube to clamp the driving signals, so that the device is prevented from being damaged due to overhigh driving voltage amplitude.

Further, the human-computer interface module adopts an ARM chip STM32F103ZET 6.

Further, the DSP control module employs a TMS320F28035 digital signal processor, the digital signal processor has a Pulse Frequency Modulation (PFM) unit, and the control of the LLC resonant cavity gain is realized by adopting PFM control, thereby realizing constant current output control.

And the DSP control module realizes the switching of the pulse base value output and the pulse peak value output according to the pulse time sequence. When the pulse peak value of the host power supply module or the slave power supply module is output, the 1 st to N (N is more than or equal to 2 and less than or equal to N) subsystems in the host power supply module or the slave power supply module work simultaneously to output pulse peak voltage and pulse peak current; when the pulse base value of the host power module or the slave power module is output, the first subsystem in the host power module or the slave power module works to output pulse base value voltage and pulse base value current. In the welding process, the required welding voltage is small in the pulse base value stage, and the required welding voltage is large in the pulse peak value stage, so that the LLC resonance modules of all subsystems can not be ensured to work at the optimal resonance point f when the pulse peak value output and the pulse base value output_s＝f_rTherefore, when the pulse peak value is output, the LLC resonant module working frequency of all the subsystems is enabled to be f_m<f_s<f_rWithin the range, when the pulse basic value is output, the LLC resonance modules of the first subsystem of the master power supply module and the first subsystem of the slave power supply module work at the optimal resonance point f_s＝f_rPrimary side power switch tube V₁、V₂、V₃And V₄Can realize zero voltage switching-on and secondary side first rectifier diode D₁And a second rectifying diode D₂Zero current turn-off can be realized, soft switching is realized on power devices on the primary side and the secondary side, the electric energy conversion efficiency is high, and the electromagnetic interference is minimum.

Furthermore, when the inversion module and the LLC resonance module output pulse peak values, the working frequency is f_m<f_s<f_rWherein f is_mIs the minimum resonant frequency, f_sTo the operating frequency, f_rFor the optimal resonant frequency, the working frequency is f when the basic value is output_s＝f_rWorking in six different working phases:

at the time of pulse peak output, the working frequency is f_m<f_s<f_r：

The LLC resonance module is in a first working phase, i.e. working time, at t₀-t₁At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel body diode of (1) is used for switching the first power switch tube V₁And a fourth power switch tube V₄The voltage at both ends is clamped to be zero and is taken as a first power switch tube V₁And a fourth power switch tube V₄The first power switch tube V creates conditions for zero voltage switching-on₁And a fourth power switch tube V₄Zero voltage is switched on, the primary current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is negative, the secondary voltage of the power transformer is positive and negative, and the first rectifier diode D₁A second rectifying diode D₂The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current rises linearly;

the LLC resonance module is in a second working phase, i.e. working time, at t₁-t₂At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The current of the anti-parallel body diode is reduced to zero, the resonance current is changed to positive through zero, and the first power switch tube V₁And a fourth power switch tube V₄Zero voltage turn-on has been achieved and current flows through the first power switch tube V₁And a fourth power switch tube V₄The primary side current of the power transformer is equal to the resonance current minus the exciting current, the polarity is kept positive, negative and positive, and the first rectifier diode D₁Remains on, the second rectifier diode D₂Keeping off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current linearly rises and changes from negative to positive;

the LLC resonance module is in a third working phase, i.e. working time, at t₂-t₃At the initial moment of the stage, the resonant current and the exciting current are equal, the current flowing through the primary side of the power transformer is zero, and the first power switch tube V is connected with the first power switch tube V₁And a fourth power switch tube V₄Keep on and all current in resonant cavityForming a circular current without transferring energy to the secondary side, the first rectifying diode D₁Zero current turn-off is realized, no reverse recovery problem exists, and as the rectifier diodes are all in the turn-off state, the secondary output voltage of the power transformer loses the excitation inductance L_mSo that the inductance L is excited_mParticipating in a resonance process, wherein the resonance current and the excitation current are always equal;

the LLC resonance module is in the fourth working phase, i.e. the working time is t₃-t₄At the initial moment of this stage, the first power switch tube V₁And a fourth power switch tube V₄Turn off, at this time, the second power switch tube V₂And a third power switch tube V₃Also keeps off, the current can not change suddenly due to the inductance in the loop, therefore, the resonant current is supplied to the first power switch tube V₁And a fourth power switch tube V₄A second power switch tube V₂And a third power switch tube V₃After the charging and discharging process is finished, the second power switch tube V₂And a third power switch tube V₃The anti-parallel diode is a second power switch tube V₂And a third power switch tube V₃Creating conditions for zero voltage turn-on; the primary current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is positive, the secondary voltage of the power transformer is converted into negative voltage, and the second rectifier diode D₂A first rectifying diode D₁The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current linearly decreases;

the LLC resonance module is in a fifth working phase, i.e. working time, at t₄-t₅At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃The second power switch tube V₂And a third power switch tube V₃Zero voltage is switched on, the primary side current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is positive, the secondary side voltage of the power transformer is positive and negative,the first rectifying diode D₁Remains off, the second rectifier diode D₂Keeping on, the excitation inductor is clamped by the output voltage, does not participate in the resonance process, and the excitation current linearly decreases;

the LLC resonance module is in a sixth working phase, i.e. working time, at t₅-t₆At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃The current of the anti-parallel body diode is reduced to zero, the resonance current is changed to negative through zero, and the second power switch tube V₂And a third power switch tube V₃Zero voltage turn-on is realized and current flows through the second power switch tube V₂And a third power switch tube V₃The primary side current of the power transformer is equal to the resonance current minus the exciting current, the polarity is kept to be positive and negative, and the first rectifier diode D₁Remains off, the second rectifier diode D₂Keeping on, the exciting inductance is clamped by the output voltage and does not participate in the resonance process, the exciting current linearly decreases and changes from positive to negative;

the LLC resonance module is in a seventh working phase, i.e. working time, at t₆-t₇At the initial moment of the stage, the resonant current and the exciting current are equal, the current flowing through the primary side of the power transformer is zero, and the second power switch tube V is connected with the first power switch tube V₂And a third power switch tube V₃Keeping on, all current in the resonant cavity forms a circular current without transferring energy to the secondary side, and the second rectifier diode D₂Zero current turn-off is realized, the problem of reverse recovery is avoided, and as the rectifier diodes are all in the turn-off state, the secondary side output voltage loses the excitation inductance L_mSo that the inductance L is excited_mParticipating in a resonance process, wherein the resonance current and the excitation current are always equal;

the LLC resonance module is in an eighth working phase, i.e. working time, at t₇-t₈At the initial moment of this stage, the second power switch tube V₂And a third power switch tube V₃Turn off, at the moment, the first power switch tube V₁And a fourth power switch tube V₄Also keeps off, the current can not change suddenly due to the inductance in the loop, therefore, the resonant current is supplied to the second power switch tube V₂And a third power switch tube V₃The first power switch tube V₁And a fourth power switch tube V₄After the charging and discharging process is finished, the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel diode conducts follow current; the primary current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is negative, the secondary voltage of the transformer is converted into upper positive and lower negative, and the first rectifier diode D₁A second rectifying diode D₂The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current rises linearly;

when the basic value is output, the working frequency is f_s＝f_r：

The LLC resonant module is in a first operating phase at t₀-t₁At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel body diode of (1) is used for switching the first power switch tube V₁And a fourth power switch tube V₄The voltage at both ends is clamped to be zero and is taken as a first power switch tube V₁And a fourth power switch tube V₄The first power switch tube V creates conditions for zero voltage switching-on₁And a fourth power switch tube V₄Zero voltage is switched on, the primary current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is negative, the secondary voltage of the power transformer is positive and negative, and the first rectifier diode D₁A second rectifying diode D₂The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current rises linearly;

the LLC resonance module is in the second working phase t₁-t₂At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The current of the anti-parallel body diode is reduced to zero, the resonance current is changed to positive through the zero point, soThe first power switch tube V₁And a fourth power switch tube V₄Zero voltage turn-on has been achieved and current flows through the first power switch tube V₁And a fourth power switch tube V₄The primary side current of the power transformer is equal to the resonance current minus the exciting current, the polarity is kept positive, negative and positive, and the first rectifier diode D₁Remains on, the second rectifier diode D₂Keeping off, the excitation inductor is clamped by the output voltage and does not participate in the resonance process, the excitation current linearly rises and changes from negative to positive, and at t₂The moment resonance current is equal to the excitation current;

the LLC resonance module is in a third working phase t₂-t₃At the initial moment of this stage, the first power switch tube V₁And a fourth power switch tube V₄Turn off, at this time, the second power switch tube V₂And a third power switch tube V₃Also keeps off, the current can not change suddenly due to the inductance in the loop, therefore, the resonant current is supplied to the first power switch tube V₁And a fourth power switch tube V₄A second power switch tube V₂And a third power switch tube V₃After the charging and discharging process is finished, the second power switch tube V₂And a third power switch tube V₃The anti-parallel diode conducts follow current; the primary current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is positive, the secondary voltage of the power transformer is converted into negative voltage, and the second rectifier diode D₂A first rectifying diode D₁The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current linearly decreases;

the LLC resonant module is in a fourth operating phase (t)₃-t₄) At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃The second power switch tube V₂And a third power switch tube V₃Zero voltage is switched on, the primary side current of the power transformer is equal to the resonance current minus the exciting current, and the exciting currentThe current is positive, the secondary side voltage of the power transformer is positive and negative, and the first rectifier diode D₁Remains off, the second rectifier diode D₂Keeping on, the excitation inductor is clamped by the output voltage, does not participate in the resonance process, and the excitation current linearly decreases;

the LLC resonant module is in a fifth operating phase (t)₄-t₅) At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃The current of the anti-parallel body diode is reduced to zero, the resonance current is changed to negative through zero, and the second power switch tube V₂And a third power switch tube V₃Zero voltage turn-on is realized and current flows through the second power switch tube V₂And a third power switch tube V₃The primary side current of the power transformer is equal to the resonance current minus the exciting current, the polarity is kept to be positive and negative, and the first rectifier diode D₁Remains off, the second rectifier diode D₂Keeping on, the exciting inductance is clamped by the output voltage and does not participate in the resonance process, the exciting current linearly decreases and changes from positive to negative, and at t₅The moment resonance current is equal to the excitation current;

the LLC resonant module is in a sixth operating phase (t)₅-t₆) At the initial moment of this stage, the second power switch tube V₂And a third power switch tube V₃Turn off, at the moment, the first power switch tube V₁And a fourth power switch tube V₄Also keeps off, the current can not change suddenly due to the inductance in the loop, therefore, the resonant current is supplied to the second power switch tube V₂And a third power switch tube V₃The first power switch tube V₁And a fourth power switch tube V₄After the charging and discharging process is finished, the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel diode conducts follow current; the primary current of the power transformer is equal to the resonance current minus the exciting current, the exciting current is negative, the secondary voltage of the power transformer is converted into positive and negative, and the first rectifier diode D₁A second rectifying diode D₂And when the excitation inductor is turned off, the excitation inductor is clamped by the output voltage and does not participate in the resonance process, and the excitation current linearly rises.

Further, when the master power module or the slave power module outputs a base current, the first subsystem in the master power module or the slave power module works and works at the optimal resonance point f_s＝f_rWhen the host power supply module or the slave power supply module outputs peak current, the 1 st-N (N is more than or equal to 2 and less than or equal to N) subsystems in the host power supply module or the slave power supply module work, and the current is equalized in parallel to output the peak current and work at f_m<f_s<f_rWithin the range.

Furthermore, when the pulse peak current is output, the 1 st-nth subsystem resonant current carries out staggered phase adjustment, so that the power output is increased, and the load of a power grid is reduced.

Furthermore, the number of the subsystems which work is changed at the same time when the pulse peak value is output is changed, so that the peak current can be adjusted in a large range, and the resonant frequency of the LLC resonant module is always at f_m<f_s<f_rWithin the range.

Compared with the prior art, the utility model has the advantages of as follows and effect:

the utility model discloses at pulse basic value stage, maintain the electric arc burning and do not extinguish, at pulse peak value stage, the molten drop grows up, under the effect of electromagnetic force, gravity, plasma flow force and surface tension, the molten drop breaks away from the welding wire and gets into the molten bath. Because the output current is in a pulse waveform, the stirring effect on the molten pool can be generated, the molten pool is promoted to flow, and fine and uniform weld joint tissues are obtained.

The utility model discloses a parallel circuit structure can select the subsystem work of different quantity according to actual need, realizes that the peak current on a large scale is adjustable, simple structure, and control is nimble, and is small, can save a large amount of spaces to adopt LLC resonance module, electric energy conversion efficiency is high, electromagnetic interference is little.

The utility model discloses can realize that the double-wire pulse MIG welds the pulse basic valueWhen outputting, the LLC resonant converter works at the optimal working point f of the resonant frequency_s＝f_rOperating in the resonant frequency range f at peak pulse output_m<f_s<f_rRealize the primary side power switch tube V₁、V₂、V₃And V₄Zero voltage turn-on, secondary side first rectifier diode D₁And a second rectifying diode D₂Zero current is turned off, and the power devices on the primary side and the secondary side realize soft switching, so that the switching loss is reduced, and the power efficiency is improved.

The utility model discloses a two-wire pulse MIG welding electrical power generating system based on LLC has combined two-wire pulse MIG to weld and has applied efficiently, and LLC electric energy conversion efficiency is high, and welding efficiency obviously improves, has controlled welding process heat input, energy-efficient effectively.

Drawings

FIG. 1 is a schematic structural diagram of a double-wire pulse MIG welding power supply system based on LLC of the present invention;

FIG. 2 is a schematic diagram of a subsystem of the present invention;

FIG. 3 is a schematic diagram of the main circuit of the subsystem of the present invention;

FIG. 4 shows a view of f_m<f_s<f_rA working waveform diagram;

FIG. 5 shows a view of f_s＝f_rA working waveform diagram;

fig. 6 is a schematic circuit diagram of the high-frequency driving module of the present invention;

fig. 7 is a schematic circuit diagram of the fault protection module of the present invention;

fig. 8a is a schematic diagram of the voltage detection circuit of the present invention;

fig. 8b is a schematic diagram of the current detection circuit of the present invention;

fig. 9a is a schematic diagram of the waveform of the synchronized phase pulse of the present invention;

fig. 9b is a schematic diagram of an alternate phase pulse waveform of the present invention;

fig. 9c is a schematic diagram of the waveform of the independent phase pulse of the present invention;

FIG. 10a is a flow chart of the human-machine interface control of the present invention;

fig. 10b is a flow chart of the synchronous phase control of the present invention;

fig. 10c is a flowchart of the alternate phase control of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following examples and drawings, but the present invention is not limited thereto.

As shown in fig. 1, a double-wire pulse MIG welding power supply system based on LLC includes a three-phase ac input power grid, a master power supply module, a slave power supply module, a human-computer interface module and an arc load; the arc loads comprise a master arc load and a slave arc load; the host power supply module, the slave power supply module and the human-computer interface module are connected with each other through a CAN bus. One end of the main machine power supply module is connected with a three-phase alternating current input power grid, and the other end of the main machine power supply module is connected with a main machine arc load; one end of the slave power supply module is connected with a three-phase alternating current input power grid, and the other end of the slave power supply module is connected with an arc load of a slave;

the human-computer interface module comprises an ARM chip, a controller, a driver and an LCD screen, wherein one end of the driver is connected with the ARM chip, and the other end of the driver is connected with the LCD screen; controller one end is connected with the ARM chip, and its other end is connected with the LCD screen, human-computer interface module is connected with DSP control module, the ARM chip adopts STM32F103ZET6, as the control core of human-computer interface, realizes human-computer interaction, welding parameter's settlement, real-time display, welding process control and pulse phase's coordinated control, the variety of improvement system function. The controller of the human-computer interface module adopts an RA8835 liquid crystal display controller.

As shown in fig. 2, the subsystem includes a main circuit, a high-frequency driving module, a DSP control module, a fault protection module, and a voltage and current detection module;

the DSP control module adopts a TMS320F28035 digital signal processor, an event manager is embedded in the digital signal processor, wherein the event manager is provided with a pulse frequency modulation unit, and the DSP control module realizes the switching of pulse basic value and pulse peak value output according to a pulse time sequence sent by a human-computer interface module;

the output end of the fault protection module and the output end of the voltage and current detection module are connected with the input end of the DSP control module;

the input end of the high-frequency driving module is connected with the output end of the DSP control module;

the voltage and current detection module is connected with the DSP control module;

the input end of the fault protection module is connected with a three-phase alternating current input power grid;

and the output end of the output rectifying and filtering module of the main circuit is connected with the input end of the voltage and current detection module.

And the DSP control module is connected with the human-computer interface module through a CAN bus.

As shown in fig. 3, the main circuit includes an input rectification filter module, an inverter module, an LLC resonant module, a power transformer, and an output rectification filter module, wherein the input rectification filter module, the inverter module, the LLC resonant module, the power transformer, and the output rectification filter module are connected in sequence; the input end of the input rectifying and filtering module is connected with a three-phase alternating current input power grid; the output end of the output rectifying and filtering module is connected with an arc load;

the inversion module mainly comprises four power switch tubes, the four power switch tubes are all MOSFET tubes, and a Driver1 in the figure is a first power switch tube V₁A drive signal Driver2 is a second power switch tube V₂A drive signal Driver3 is a third power switch tube V₃A drive signal Driver4 is a fourth power switch tube V₄A drive signal; the D pole of the first power switch tube is connected with the input rectifying and filtering module, the S pole of the first power switch tube is connected with the D pole of the third power switch tube, and the G pole of the first power switch tube is connected with the high-frequency driving module; the D pole of the second power switch tube is connected with the input rectifying and filtering module, the S pole is connected with the D pole of the fourth power switch tube, and the G pole is connected with the high-frequency driving moduleConnecting the blocks; the D pole of the third power switch tube is connected with the S pole of the first power switch tube, the S pole is connected with the input rectifying and filtering module, and the G pole is connected with the high-frequency driving module; the D pole of the fourth power switch tube is connected with the S pole of the second power switch tube, the S pole is connected with the input rectifying and filtering module, and the G pole is connected with the high-frequency driving module;

the four power switch tubes are controlled to be switched on or switched off by Pulse Frequency Modulation (PFM) signals provided by a high-frequency driving module, and the first power switch tube V₁And a fourth power switch tube V₄And simultaneously on or off, the second power switch tube V₂And a third power switch tube V₃Simultaneously turned on or off, and V₁And V₄And V₂And V₃Alternately switching on and off, in order to avoid damaging the power switch tube due to straight-through, two power switch tubes V of the same bridge arm₁And V₃And V₂And V₄With dead time in between.

The LLC resonance module comprises a resonance inductor L_rAnd an excitation inductor L_mAnd a resonance capacitor C_rSaid resonant inductor L_rAnd an excitation inductor L_mResonant capacitor C_rThe equivalent load and the resonant cavity are formed together; one end of the resonant capacitor is connected with the S pole of the first power switch tube, the other end of the resonant capacitor is connected with the resonant inductor, the excitation inductor is connected with the power transformer in parallel, one end of the excitation inductor is connected with the resonant inductor, and the other end of the excitation inductor is connected with the D pole of the fourth power switch tube; the resonance inductor L_rAnd an excitation inductor L_mResonant capacitor C_rAnd the equivalent load form a resonant cavity.

The output rectifying and filtering module comprises a first rectifying diode D₁A second rectifying diode D₂And a second capacitor C₂。

As shown in FIG. 4, V _gs1、V _gs2、V _gs3、V_gs4 are respectively high-frequency driving signals of a first power switch tube, a second power switch tube, a third power switch tube and a fourth power switch tube, I_D1、I_D2Respectively a first rectifying diode,Current of a second rectifying diode, and the LLC resonant module has working frequency f_m<f_s<f_rInternally, the work is in the following eight distinct phases:

the LLC resonant module is in a first operating phase (t)₀-t₁) At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel body diode of (1) is used for switching the first power switch tube V₁And a fourth power switch tube V₄The voltage at both ends is clamped to be zero and is taken as a first power switch tube V₁And a fourth power switch tube V₄The first power switch tube V creates conditions for zero voltage switching-on₁And a fourth power switch tube V₄Zero voltage is switched on, and the primary side current of the power transformer is equal to the resonant current I_LrMinus the exciting current I_LmThe exciting current is negative, the secondary side voltage of the power transformer is positive and negative, and the first rectifier diode D₁A second rectifying diode D₂The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current rises linearly;

the LLC resonant module is in a second operating phase (t)₁-t₂) At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The current of the anti-parallel body diode is reduced to zero, the resonance current is changed to positive through zero, and the first power switch tube V₁And a fourth power switch tube V₄Zero voltage turn-on has been achieved and current flows through the first power switch tube V₁And a fourth power switch tube V₄The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmAnd the polarity is kept positive up and negative down, the first rectifier diode D₁Remains on, the second rectifier diode D₂Keeping off, the exciting inductance is clamped by output voltage and does not participate in resonance process, and the exciting current I_LmLinearly increasing from negative to positive;

the LLC resonant module is in a third operating phase (t)₂-t₃) At the stageAt the initial moment of the segment, the resonant current I_LrAnd an excitation current I_LmEqual, the current flowing through the primary side of the power transformer is zero, and the first power switch tube V₁And a fourth power switch tube V₄Keeping on, all current in the resonant cavity forms a circular current without transferring energy to the secondary side, and the first rectifier diode D₁Zero current turn-off is realized, the problem of reverse recovery is avoided, and as the rectifier diodes are all in the turn-off state, the secondary side output voltage loses the excitation inductance L_mSo that the inductance L is excited_mParticipating in a resonance process when the resonance current I_LrAnd an excitation current I_LmAre always equal;

the LLC resonant module is in a fourth operating phase (t)₃-t₄) At the initial moment of this stage, the first power switch tube V₁And a fourth power switch tube V₄Turn off, at this time, the second power switch tube V₂And a third power switch tube V₃Also remains off, the current cannot jump suddenly due to the presence of inductance in the loop, and therefore the resonant current I_LrFor the first power switch tube V₁And a fourth power switch tube V₄A second power switch tube V₂And a third power switch tube V₃After the charging and discharging process is finished, the second power switch tube V₂And a third power switch tube V₃The anti-parallel diode is a second power switch tube V₂And a third power switch tube V₃The zero voltage turn-on creates conditions. The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmExcitation current I_LmThe secondary side voltage of the power transformer is positive, the secondary side voltage of the power transformer is converted into negative voltage, and the second rectifier diode D₂A first rectifying diode D₁The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current linearly decreases;

the LLC resonant module is in a fifth operating phase (t)₄-t₅) At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃The second power switch tube V₂And a third power switch tube V₃Zero voltage is switched on, and the primary side current of the power transformer is equal to the resonant current I_LrMinus the exciting current I_LmExcitation current I_LmPositive, negative and positive under the secondary side voltage of the power transformer, and the first rectifier diode D₁Remains off, the second rectifier diode D₂Kept on, said exciting inductor being clamped by the output voltage and not participating in the resonance process, said exciting current I_LmThe linear decrease;

the LLC resonant module is in a sixth operating phase (t)₅-t₆) At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃Has been reduced to zero, the resonant current I_LrBecomes negative after passing through zero point, and the second power switch tube V₂And a third power switch tube V₃Zero voltage turn-on is realized and current flows through the second power switch tube V₂And a third power switch tube V₃The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmAnd the polarity is kept positive and negative, the first rectifier diode D₁Remains off, the second rectifier diode D₂Kept on, said exciting inductor being clamped by the output voltage and not participating in the resonance process, said exciting current I_LmLinearly decreasing from positive to negative;

the LLC resonant module is in a seventh operating phase (t)₆-t₇) At the initial moment of this phase, the resonant current I_LrAnd an excitation current I_LmThe current flowing through the primary side of the power transformer is zero, and the second power switch tube V is equal to the current flowing through the primary side of the power transformer₂And a third power switch tube V₃Keeping on, all current in the resonant cavity forms a circular current without transferring energy to the secondary side, and the second rectifier diode D₂Zero current turn-off is realized, the problem of reverse recovery is avoided, and as the rectifier diodes are all in the turn-off state, the secondary side output voltage loses the excitation inductance L_mSo as to excite the fieldFeeling L_mParticipating in a resonance process when the resonance current I_LrAnd an excitation current I_LmAre always equal;

the LLC resonant module is in an eighth operating phase (t)₇-t₈) At the initial moment of this stage, the second power switch tube V₂And a third power switch tube V₃Turn off, at the moment, the first power switch tube V₁And a fourth power switch tube V₄Also remains off, the current cannot jump suddenly due to the presence of inductance in the loop, and therefore the resonant current I_LrFor the second power switch tube V₂And a third power switch tube V₃The first power switch tube V₁And a fourth power switch tube V₄After the charging and discharging process is finished, the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel diode is a first power switch tube V₁And a fourth power switch tube V₄The zero voltage turn-on creates conditions. The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmExcitation current I_LmThe voltage of the secondary side of the power transformer is converted into positive and negative, and the first rectifier diode D₁A second rectifying diode D₂The excitation inductor is switched off, the excitation inductor is clamped by output voltage and does not participate in the resonance process, and the excitation current rises linearly;

as shown in FIG. 5, the LLC resonant module operates at the optimum operating point f of the resonant frequency_s＝f_rWhen working in six different phases:

the LLC resonant module is in a first operating phase (t)₀-t₁) At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel body diode of (1) is used for switching the first power switch tube V₁And a fourth power switch tube V₄The voltage at both ends is clamped to be zero and is taken as a first power switch tube V₁And a fourth power switch tube V₄The first power switch tube V creates conditions for zero voltage switching-on₁And a fourth power switchPipe V₄Zero voltage is switched on, and the primary side current of the power transformer is equal to the resonant current I_LrMinus the exciting current I_LmExcitation current I_LmIs negative, the secondary side voltage of the power transformer is up-down negative, and the first rectifier diode D₁A second rectifying diode D₂Turn off, the exciting inductor is clamped by output voltage and does not participate in resonance process, and the exciting current I_LmLinearly increasing;

the LLC resonant module is in a second operating phase (t)₁-t₂) At the initial moment of this stage, the current flows through the first power switch tube V₁And a fourth power switch tube V₄The current of the anti-parallel body diode is reduced to zero, the resonance current is changed to positive through zero, and the first power switch tube V₁And a fourth power switch tube V₄Zero voltage turn-on has been achieved and current flows through the first power switch tube V₁And a fourth power switch tube V₄The primary side current of the power transformer is equal to the resonance current minus the exciting current, the polarity is kept positive, negative and positive, and the first rectifier diode D₁Remains on, the second rectifier diode D₂Keeping off, the exciting inductance is clamped by output voltage and does not participate in resonance process, and the exciting current I_LmLinearly rising from negative to positive at t₂Time of day resonant current I_LrAnd an excitation current I_LmEqual;

the LLC resonant module is in a third operating phase (t)₂-t₃) At the initial moment of this stage, the first power switch tube V₁And a fourth power switch tube V₄Turn off, at this time, the second power switch tube V₂And a third power switch tube V₃Also keeps off, the current can not change suddenly due to the inductance in the loop, therefore, the resonant current is supplied to the first power switch tube V₁And a fourth power switch tube V₄A second power switch tube V₂And a third power switch tube V₃After the charging and discharging process is finished, the second power switch tube V₂And a third power switch tube V₃Is connected in parallel with the diodeConducting follow current as the second power switch tube V₂And a third power switch tube V₃The zero voltage turn-on creates conditions. The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmExcitation current I_LmThe secondary side voltage of the power transformer is positive, the secondary side voltage of the power transformer is converted into negative voltage, and the second rectifier diode D₂A first rectifying diode D₁Turn off, the exciting inductor is clamped by output voltage and does not participate in resonance process, and the exciting current I_LmThe linear decrease;

the LLC resonant module is in a fourth operating phase (t)₃-t₄) At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃The second power switch tube V₂And a third power switch tube V₃Zero voltage is switched on, and the primary side current of the power transformer is equal to the resonant current I_LrMinus the exciting current I_LmExcitation current I_LmPositive, negative and positive under the secondary side voltage of the power transformer, and the first rectifier diode D₁Remains off, the second rectifier diode D₂Kept on, said exciting inductor being clamped by the output voltage and not participating in the resonance process, said exciting current I_LmThe linear decrease;

the LLC resonant module is in a fifth operating phase (t)₄-t₅) At the initial moment of this stage, the current flows through the second power switch tube V₂And a third power switch tube V₃Has been reduced to zero, the resonant current I_LrBecomes negative after passing through zero point, and the second power switch tube V₂And a third power switch tube V₃Zero voltage turn-on is realized and current flows through the second power switch tube V₂And a third power switch tube V₃The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmAnd the polarity is kept positive and negative, the first rectifier diode D₁Remains off, the second rectifier diode D₂Kept on, the exciting inductor is clamped by the output voltage and does not participate in the resonance processSaid excitation current I_LmLinearly decreasing from positive to negative at t₅Time of day resonant current I_LrAnd an excitation current I_LmEqual;

the LLC resonant module is in a sixth operating phase (t)₅-t₆) At the initial moment of this stage, the second power switch tube V₂And a third power switch tube V₃Turn off, at the moment, the first power switch tube V₁And a fourth power switch tube V₄Also remains off, the current cannot jump suddenly due to the presence of inductance in the loop, and therefore the resonant current I_LrFor the second power switch tube V₂And a third power switch tube V₃The first power switch tube V₁And a fourth power switch tube V₄After the charging and discharging process is finished, the first power switch tube V₁And a fourth power switch tube V₄The anti-parallel diode is a first power switch tube V₁And a fourth power switch tube V₄The zero voltage turn-on creates conditions. The primary side current of the power transformer is equal to the resonance current I_LrMinus the exciting current I_LmExcitation current I_LmThe voltage of the secondary side of the power transformer is converted into positive and negative, and the first rectifier diode D₁A second rectifying diode D₂Turn off, the exciting inductor is clamped by output voltage and does not participate in resonance process, and the exciting current I_LmLinearly increasing;

as shown in fig. 6, the high frequency driving module schematic diagram of the MOSFET full bridge LLC of the present invention has the isolation and power amplification functions. The primary side of the driving circuit adopts a high-speed MOSFET N_1b～N_4bThe formed totem-pole type driving structure can realize quick switching and increase driving power of driving pulses PFM _1 and PFM _2 sent by the DSP control module. A voltage regulator tube (D) is adopted at the secondary side of the drive circuit_9b～D_10b、D_16b～D_17b、D_23b～D_24b、D_30b～D_31b) Voltage stabilizing and clamping the driving pulse to avoid passing through the driving transformer T_1bAnd T_2bHigh-voltage MOSFET V of primary side conversion circuit of damaged converter due to overhigh amplitude of drive pulse obtained by conversion₁～V₄(ii) a Capacitor C_7b～C_10bFor high voltage MOSFET V₁～V₄Accelerating driving is carried out to eliminate adverse influence of turn-on time delay caused by the Miller effect of the MOSFET at the turn-on moment as much as possible; d_13bAnd V_1b、 D_20bAnd V_2b、D_27bAnd V_3b、D_34bAnd V_4bThe formed rapid discharge loop can accelerate the pulse back edge to be switched off when the driving pulse is switched off, and secondary switching-on caused by the Miller effect of the MOSFET at the switching-off moment is eliminated.

As shown in fig. 7, the utility model discloses a fault protection module schematic diagram, each component part all can adopt current circuit to constitute as the example, and fault protection module includes overvoltage detection module, undervoltage detection module, overflows detection module, excess temperature detection module and gate circuit. The overvoltage detection module and the undervoltage detection module are connected with a three-phase alternating current input power grid, the overcurrent detection module is connected with the power transformer, the over-temperature detection module is connected with the radiator, and the overvoltage detection module, the undervoltage detection module, the overcurrent detection module and the over-temperature detection module are all connected with a gate circuit. The overvoltage detection module and the undervoltage detection module step down a three-phase alternating current input power grid through a power frequency transformer, the three-phase alternating current input power grid is rectified into a direct current voltage signal through a bridge rectifier circuit and then is supplied to a resistor voltage division circuit, and the sizes of resistors (R39, R26, R38 and R24) of the bridge circuit are respectively adjusted, so that overvoltage and undervoltage thresholds can be changed, and the overvoltage and undervoltage protection effect can be achieved. The over-temperature detection module realizes over-temperature protection by detecting the disconnection of a temperature relay on the radiator to obtain a disconnection signal and send the disconnection signal to the inverting input end of the comparator U6A, and the comparator U6A is used as a comparator to carry out voltage comparison. The non-inverting end of the circuit is a given reference voltage, when the temperature of the radiator is lower than the threshold temperature of the temperature relay, the temperature relay is closed, the inverting input end of the comparator U6A is at a low level, and the comparator U6A outputs a high level; when the temperature of the radiator is higher than the temperature threshold of the temperature relay, the temperature relay is switched off, the inverting input end of the comparator U6A is at a high level, the comparator U6A outputs a low level, and the signal can cause the fault protection of the DSP control module to be interrupted. The overcurrent detection module detects that a primary current signal is sent to the inverting input end of the comparator U6B after being filtered, the comparator U6B serving as the comparator has the non-inverting input end serving as a given reference current, and when the detected primary current is larger than the given reference current, the comparator U6B outputs a low level, and the signal can cause the fault protection interruption of the DSP control module. In the figure, the output of an and gate U13(CD4073B) is connected with an external interrupt pin of a DSP control module through a photocoupler U14(TLP521-1), when overvoltage, undervoltage, overtemperature and overcurrent detection signals output by an output end of the and gate U13 have overvoltage, undervoltage, overtemperature and overcurrent faults, the and gate outputs a low level, and outputs the low level after being photocoupled by the U14, and the low level is used as a trigger signal of the fault protection interrupt of the DSP to a TZ1 pin of the DSP to enter a fault protection interrupt service subprogram, so that fault protection is realized;

as shown in fig. 8a and 8b, which are the schematic diagram of the voltage detection circuit and the schematic diagram of the current detection circuit of the present invention, the sampling of the precision resistor obtains the voltage signal, the voltage follower N2B performs isolation and buffering, the voltage is divided by the resistor R9 and the resistor R10, and the voltage regulator tube V3 performs voltage stabilization to obtain the voltage signal less than or equal to 3.3V; output current is sampled by a shunt, converted into a differential voltage signal between + GND and-GND, filtered by a capacitor C13 and a capacitor C14, amplified to a proper multiple by a differential amplifier TLC4501 by adjusting the size of a resistor (R12-R18), isolated and buffered by a voltage follower N2D, divided by a resistor R22 and a resistor R23, and protected by a voltage regulator tube V2, so that a voltage signal less than or equal to 3.3V is obtained. The voltage signal and the current signal obtained by sampling realize A/D conversion through software, are converted into digital signals, and are sent to a DSP control module to form closed-loop control, so that constant current output at different stages is realized;

as shown in fig. 9a, 9b and 9c, the present invention is a current pulse period phase diagram of the master power module and the slave power module. In the synchronous phase, the pulse current of the master power supply and the slave power supply has 2 stages in one cycle: a base phase T1 and a peak phase T2; when the phases are alternated, the pulse current of the master power supply and the slave power supply has 4 stages in one period: main unitA peak slave base value stage T1, a master base value slave base value stage T2, a master base value slave peak value stage T3 and a master base value slave base value stage T4; and when the phases are independent, judging that the host power supply module and the slave power supply module respectively enter a base value stage and a peak value stage to be freely switched after the arc striking is successful, wherein the phase angle between the host and the slave is not strict. The first subsystem of the master machine and the first subsystem of the slave machine work at the optimal resonance point f in the fundamental value stage_s＝f_rOutputting base voltage and base current, and enabling the 1 st-nth (N is more than or equal to 2 and less than or equal to N) subsystems in the host and the slave to work in a frequency range f at the peak stage_m<f_s<f_rAs long as the set current is ensured to be less than or equal to N times of the base value current, zero-voltage switching-on of the primary side power switching tube and zero-current switching-off of the secondary side rectifier diode can be realized, the whole system has high efficiency and small power loss;

fig. 10a, 10b and 10c show flowcharts of the man-machine interface, synchronous and alternative phase control method according to the present invention. Different phases adopt different stage control methods, and the control is as follows:

synchronous phase: after the arc striking of the master power module and the slave power module is successful, the master and the slave simultaneously enter a pulse basic value stage, a first subsystem in the master power module and a first subsystem in the slave power module work, a timer is started for timing, the time T1 of the stage is calculated, the peak value stage of the master and the slave is switched to work when the time T1 is up, the 1-nth (N is more than or equal to 2 and less than or equal to N) subsystems in the master power module and the slave power module work, the timer is started for timing, the time T2 of the stage is calculated, and the stage of switching to the basic value stage of the master and the slave is switched to work when the time T2 is up, and the steps.

Alternate phase: after arc striking is successful, the master power module and the slave power module enter a master pulse peak value stage and a slave pulse basic value stage, the 1 st-N (N is more than or equal to 2 and less than or equal to N) subsystems of the master power module work, the first subsystem in the slave power module works, a timer is started to time, the time T1 of the stage is calculated, the stage is switched to the master basic value stage and the slave basic value stage to work when the time T1 is up, the first subsystem in the master power module and the first subsystem in the slave power module work, the timer is started to time, the time T2 of the stage is calculated, the stage is switched to the master basic value stage and the slave peak value stage to work when the time T2 is up, the first subsystem in the master power module works, the 1 st-N (N is more than or equal to 2 and less than or equal to N) subsystems in the slave power module work, the timer is started to time, the time T3 of the stage is calculated, and the time T3 of the, and the first subsystem in the master machine power supply module and the first subsystem in the slave machine power supply module work, a timer is started for timing, the time T4 of the period is calculated, and the period is switched to a master machine pulse peak value period and a slave machine pulse basic value period when the time T4 is up, and the steps are repeated.

Independent phase: the host power supply module enters a pulse peak value stage and a pulse base value stage for switching after arc striking is successful, the slave power supply module enters the pulse peak value stage and the pulse base value stage for switching after arc striking is successful, and the host and the slave have no strict phase relation.

The system realizes cooperative control of the host power supply module and the slave power supply module through interactive communication between the human-computer interface module and the DSP control module, and the control method comprises the following steps:

the human-computer interface module detects whether a welding gun switch is closed, if the welding gun switch is closed, an arc striking command is sent, an air valve is started to supply air in advance, the wire is slowly fed and an arc is struck, the DSP control module is initialized and communicates with the human-computer interface module through a CAN (controller area network), the DSP control module detects whether the arc striking command sent by the human-computer interface module is received, if the arc striking command is received, arc striking control is executed, and if the arc striking command is not received, the next command of the human-computer interface module is;

the DSP control module receives an arc striking instruction from the human-computer interface module and then enters an arc striking control stage, at the moment, all subsystems in the host power supply module and the slave power supply module work simultaneously to output peak current, the DSP control module judges whether a fault occurs or not, if the fault occurs, a fault signal is sent to the human-computer interface module, if the fault does not occur, whether the current exceeds a certain threshold or not is detected, if the current does not exceed the threshold, arc striking control is continuously executed, if the current exceeds the certain threshold, arc striking success is judged, an arc striking success instruction is sent to the human-computer interface module, the human-computer interface module judges whether the fault signal of the DSP control module is received or not, if the fault signal is received, all outputs are closed and gas feeding is stopped, if the fault signal is not received, whether an arc striking success instruction is received or not is judged, if the arc striking success instruction is received, a pulse cycle instruction is sent, the DSP control module detects whether a pulse circulation instruction of the human-computer interface module is received, if the pulse circulation instruction is received, pulse base value and pulse peak value output switching time sequence control is carried out, and constant current in the pulse base value stage and constant current in the pulse peak value stage are connected in parallel to realize current sharing and constant current control;

the DSP control module realizes the switch switching of current output in a pulse base value stage and a pulse peak value stage according to a pulse cycle instruction sent by the human-computer interface module, and when the pulse peak value of the host power supply module or the slave power supply module is output, the 1 st to N (N is more than or equal to 2 and less than or equal to N) subsystems inside the host power supply module or the slave power supply module work simultaneously to output pulse peak voltage and pulse peak current; when the pulse base value of the host power module or the slave power module is output, the first subsystem in the host power module or the slave power module works to output pulse base value voltage and pulse base value current. When the pulse basic value is output, the LLC resonance module of one subsystem in the host power module and the slave power module works at the optimal working point f of the resonance frequency_s＝f_rWhen the pulse peak value is output, the 1 st-nth (N is more than or equal to 2 and less than or equal to N) subsystems in the host power supply and the slave power supply are connected in parallel for current sharing output, when the set peak current is different, the current shared by each subsystem is different, the voltage also fluctuates, as long as the set peak current is ensured to be less than or equal to N times of the base value current, the zero-voltage switching-on of the primary side MOSFET power switch tube and the zero-current switching-off of the secondary side rectifier diode can be realized, and at the moment, the electric energy conversion efficiency of the system is still higher than that of a hard switch or;

in the welding process, the DSP control module continuously detects whether a fault occurs, if the fault occurs, a fault signal is sent to the human-computer interface module, if the fault does not occur, whether an arc receiving instruction is received or not is judged, if the arc receiving instruction is received, arc receiving control is executed, and if the arc receiving instruction is not received, pulse circulation is continued; the human-computer interface module continuously detects whether a fault signal is received, if the fault signal is received, all outputs are closed, wire feeding and air supply are stopped, if the fault signal is not received, whether a welding gun switch is closed is judged, if the welding gun switch is closed, the welding gun switch is communicated with the DSP control module continuously to detect the fault signal, if the welding gun switch is disconnected, the human-computer interface module sends an arc receiving instruction to the DSP control module and stops wire feeding, and after the DSP control module executes arc receiving control, the human-computer interface module stops air supply and enters a standby state. A and B in the figure represent turning marks of the flow chart.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be equivalent replacement modes, and all are included in the scope of the present invention.

Claims

1. A double-wire pulse MIG welding power supply system based on LLC is characterized by comprising a three-phase alternating current input power grid, a host power supply module, a slave power supply module, a human-computer interface module and an arc load; the arc loads comprise a master arc load and a slave arc load; the master power supply module and the slave power supply module are both connected with a three-phase alternating current input power grid; the main machine power supply module and the slave machine power supply module are respectively connected with a main machine electric arc load and a slave machine electric arc load; the human-computer interface module is connected with the host power supply module and the slave power supply module through a CAN bus;

the host power supply module and the slave power supply module have the same structure and are mainly formed by connecting N subsystems in parallel; the subsystem comprises a main circuit, a high-frequency driving module, a DSP control module, a fault protection module and a voltage and current detection module; the DSP control module is connected with a fault protection module, a high-frequency driving module and a voltage and current detection module, the fault protection module is connected with the input end of the main circuit, and the voltage and current detection module is connected with the output end of the main circuit;

2. The LLC-based dual-wire pulse MIG welding power supply system of claim 1, wherein said inverter module consists essentially of four power switching tubes, a first power switching tube V₁A second power switch tube V₂And a third power switch tube V₃And a fourth power switch tube V₄The D pole of the first power switch tube is connected with the input rectification filter module, the S pole of the first power switch tube is connected with the D pole of the third power switch tube, and the G pole of the first power switch tube is connected with the high-frequency driving module; the D pole of the second power switch tube is connected with the input rectification filter module, the S pole of the second power switch tube is connected with the D pole of the fourth power switch tube, and the G pole of the second power switch tube is connected with the high-frequency driving module; the D pole of the third power switch tube is connected with the S pole of the first power switch tube, the S pole of the third power switch tube is connected with the input rectification filter module, and the G pole of the third power switch tube is connected with the high-frequency driving module; and the D pole of the fourth power switch tube is connected with the S pole of the second power switch tube, the S pole of the fourth power switch tube is connected with the input rectification filter module, and the G pole of the fourth power switch tube is connected with the high-frequency driving module.

3. The LLC-based dual-wire pulse MIG welding power supply system of claim 1, wherein said LLC resonance module mainTo be controlled by a resonant inductor L_rAnd an excitation inductor L_mAnd a resonant capacitor C_rComposition is carried out; the resonant capacitor C_rOne end of the first power switch tube is connected with the S pole of the first power switch tube, and the other end of the first power switch tube is connected with the resonant inductor C_rConnection, said excitation inductance L_mConnected in parallel with the power transformer, and having one end connected with the resonance inductor L_rThe other end of the third power switch tube is connected with the D pole of the fourth power switch tube; the resonance inductor L_rAnd an excitation inductor L_mResonant capacitor C_rAnd the equivalent load form a resonant cavity; the equivalent load mainly comprises a power transformer, an output rectifying and filtering module and an arc load.

4. The LLC-based dual-wire pulse MIG welding power supply system of claim 1, wherein said output rectifying and filtering module comprises a first rectifying diode D₁A second rectifying diode D₂And a second capacitor C₂(ii) a The first rectifying diode D₁And a second rectifying diode D₂Is connected with the second capacitor C₂Anode connection, the first rectifier diode D₁Is connected with the power transformer, and the second rectifying diode D₂The anode of the second capacitor C is connected with the other end of the power transformer₂The negative electrode is connected to ground.

5. The LLC-based twin-wire pulse MIG welding power supply system of claim 1, wherein the fault protection module includes an overvoltage detection module, an undervoltage detection module, an overcurrent detection module, an overtemperature detection module, and a gate circuit; the overvoltage detection module and the undervoltage detection module are connected with a three-phase alternating current input power grid, the overcurrent detection module is connected with the power transformer, the over-temperature detection module is connected with the radiator, and the overvoltage detection module, the undervoltage detection module, the overcurrent detection module and the over-temperature detection module are all connected with a gate circuit.

6. The LLC-based twin-wire pulse MIG welding power supply system of claim 1, wherein the primary side of the high-frequency drive module employs a totem-pole type drive structure.

7. The LLC-based dual-wire pulse MIG welding power supply system of claim 1, wherein said human interface module employs an ARM chip STM32F103ZET 6.

8. The LLC-based dual-wire pulse MIG welding power supply system of claim 1 wherein the DSP control module employs a TMS320F28035 digital signal processor having a pulse frequency modulation unit.