CN210254637U

CN210254637U - SiC-based digital control circuit for fast-frequency pulse TIG welding power supply

Info

Publication number: CN210254637U
Application number: CN201920788500.4U
Authority: CN
Inventors: 王振民; 吴健文; 范文艳; 钟启明
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2019-05-29
Filing date: 2019-05-29
Publication date: 2020-04-07
Anticipated expiration: 2029-05-29

Abstract

The utility model provides a quick pulse TIG welding power supply digital control circuit based on SiC, its characterized in that: the device comprises a control system, an electric signal sampling feedback module and a driving module; the driving module comprises a SiC high-frequency driving circuit and a modulation switching tube driving circuit; the control system is connected with the SiC high-frequency driving circuit through the isolation I, and the SiC high-frequency driving circuit is respectively connected with SiC power switch tubes of the direct-current power supply I and the direct-current power supply II; the control system is connected with the modulation switching tube driving circuit through the second isolator, and the modulation switching tube driving circuit is connected with an IGBT switching tube of the modulation circuit; the control system is also connected with the electric signal sampling feedback module. The control circuit adopts isolation protection, effectively prevents the switch tube from being damaged, can avoid electromagnetic interference, avoids generating voltage peak to cause false triggering, and has good driving effect.

Description

SiC-based digital control circuit for fast-frequency pulse TIG welding power supply

Technical Field

The utility model relates to a welding equipment technical field, more specifically say, relate to quick pulse TIG welding power supply digital control circuit frequently based on SiC.

Background

In recent years, the fast frequency pulse TIG welding technology becomes the research focus in the field of pulse TIG welding at home and abroad. The fast-frequency pulse TIG welding can improve the electric arc contraction degree of the pulse TIG welding, improve the electric arc energy density and the electric arc stiffness, refine welding seam crystal grains and improve the welding seam mechanical property.

The inversion frequency of the fast-frequency pulse TIG welding power supply developed by the SiC power device can reach 200kHz, the loss is low, the control precision is high, and regular fast-frequency pulse current waveforms of 20kHz and above can be stably output. The fast-frequency pulse TIG welding technology adds the modulation of high-frequency current, which can generate strong electromagnetic interference on a welding power supply, and particularly has stronger influence on SiC power devices. The SiC MOSFET-based fast-frequency pulse TIG welding power supply has the advantages of high-frequency and high-voltage working state, high response speed, high pulse frequency current output and the like, but has the technical problems of more interference factors, high control difficulty, easy damage of a power switching tube due to voltage spikes and the like.

SUMMERY OF THE UTILITY MODEL

For overcoming the shortcoming and not enough among the prior art, the utility model aims to provide a quick pulse TIG welding power supply digital control circuit based on SiC, adopt isolation protection, effectively prevent that the switch tube from taking place to damage, can avoid electromagnetic interference, avoid producing the voltage spike and arouse the spurious triggering, have good drive effect.

In order to achieve the above purpose, the utility model discloses a following technical scheme realizes: a SiC-based digital control circuit for a fast-frequency pulse TIG welding power supply comprises a first direct-current power supply, a second direct-current power supply and a modulation circuit; the method is characterized in that: the device comprises a control system, an electric signal sampling feedback module and a driving module; the driving module comprises a SiC high-frequency driving circuit and a modulation switching tube driving circuit; the control system is connected with the SiC high-frequency driving circuit through the isolation I, and the SiC high-frequency driving circuit is respectively connected with the SiC power switch tubes of the direct-current power supply I and the direct-current power supply II so as to drive the SiC power switch tubes of the direct-current power supply I and the direct-current power supply II by the control system; the control system is connected with the modulation switching tube driving circuit through the second isolation switch, and the modulation switching tube driving circuit is connected with the IGBT switching tube of the modulation circuit so as to drive the IGBT switching tube of the modulation circuit by the control system; the control system is also connected with the electric signal sampling feedback module.

In the control circuit of the utility model, the SiC high-frequency drive circuit receives the PWM signal output by the control system, and realizes the drive control of the SiC power switch tube of the DC power supply I and the DC power supply II; and the modulation switching tube driving circuit receives the PWM signal output by the control system, and realizes the driving control of the IGBT switching tube of the modulation circuit, thereby regulating and controlling the output characteristic of the fast-frequency pulse TIG welding power supply. The electric signal sampling feedback module samples current and voltage, and inputs the current and voltage into the control system for digital filtering and PID control processing. The control system is connected with the SiC high-frequency drive circuit and the modulation switch tube drive circuit in a sampling isolation mode; the protection circuit has multiple protection functions, and can prevent the switch tube from being damaged while effectively driving the switch tube; the problems of overhigh transient voltage and transient current and electromagnetic interference in the driving process of the SiC power switch tube can be inhibited, the voltage spike is prevented from generating to cause false triggering, and the drive effect is good.

Preferably, the control system is connected with the SiC high-frequency driving circuit through the isolation one, and the SiC high-frequency driving circuit is connected with the SiC power switch tubes of the direct-current power supply one and the direct-current power supply two, which means that:

the control system is connected with the SiC high-frequency drive circuit through an isolation drive chip with the model number of ISO5451, and the isolation drive chip is also connected with a first drive power supply circuit; and the SiC high-frequency driving circuit is connected with SiC power switch tubes of the first direct-current power supply and the second direct-current power supply.

Compare with current fast pulse TIG welding power supply technique frequently, the utility model discloses a SiC power switch tube faces the problem at the high-frequency oscillation peak as main power device, makes SiC power switch tube misleading or is punctured easily, and this is the key place that influences SiC power switch tube grid drive reliability. The isolation driving chip with the type ISO5451 has the magnetic isolation characteristic, can provide functions of short-circuit protection, under-voltage protection, Miller clamping protection and the like for the SiC high-frequency driving circuit, can effectively reduce or eliminate oscillation voltage spikes, and ensures the working reliability of the SiC welding power supply.

Preferably, the SiC high-frequency driving circuit comprises a capacitor C304, a capacitor C305, a voltage regulator tube ZD301, a diode D302, a diode D303, a resistor R310, a resistor R311, a resistor R312 and a resistor R313;

a pin CLAMP of the isolation driving chip is connected with a grid electrode of the SiC power switch tube; the gate of the SiC power switch tube is grounded through a resistor R313 and a capacitor C305 which are connected in parallel; a pin OUT of the isolation driving chip is connected with a grid electrode of the SiC power switch tube through a resistor R312; the diode D303 and the resistor R311 are connected in series and then connected in parallel to the resistor R312; a pin OUT of the isolation driving chip is connected with a drain electrode of the SiC power switch tube through a resistor R310 and a diode D302 which are connected in series; the pin OUT of the isolation driving chip is also grounded through a capacitor C304 and a voltage stabilizing diode ZD301 which are connected in parallel; the terminal DESAT of the isolation driving chip is connected with the terminal OUT of the isolation driving chip. The SiC high-frequency driving circuit has a protection effect on the grid electrode of the SiC power switch tube.

Preferably, the control system is connected with the modulation switching tube driving circuit through the second isolator, and the modulation switching tube driving circuit is connected with an IGBT switching tube of the modulation circuit, which means that: the control system is connected with a modulation switching tube driving circuit through an optical coupling isolation chip, and the modulation switching tube driving circuit is connected with an IGBT switching tube of the modulation circuit.

Preferably, the modulation switching tube driving circuit comprises an NPN triode Q401, an NPN triode Q402, an NPN triode Q404, a PNP triode Q403 and a driving power supply circuit two;

the output end of the optical coupling isolation chip is connected with the base electrode of an NPN triode Q401 through a resistor R402, a resistor R403 and a diode D402 which are connected in sequence; the resistor R403 is connected with a capacitor C401 in parallel; the diode D403 is connected in parallel with the diode D402 in the reverse direction; the junction of the resistor R403 and the diode D402 is connected with the collector of the NPN triode Q401 through the diode D401; the collector of the NPN triode Q401 is also connected with the positive pole of the driving power supply circuit through a resistor R404;

the connection part of the resistor R402 and the resistor R403 is connected with the base electrode of the NPN triode Q402 through a resistor R408 and a diode D408 which are connected in sequence; the resistor R408 is connected with a capacitor C403 in parallel; the diode D408 is reversely connected with a diode D409 in parallel; the junction of the resistor R408 and the diode D408 is connected with the collector of the NPN triode Q402 through a diode D407; the collector of the NPN triode Q402 is also connected with the positive pole of the driving power supply circuit through a resistor R409; an emitting electrode of the NPN triode Q401 and an emitting electrode of the NPN triode Q402 are respectively connected with the negative electrode of the driving power supply circuit II;

the collector of the NPN triode Q401 is connected with the base of the PNP triode Q403 through a resistor R405 and a diode D405 which are connected in sequence; the resistor R405 is connected with a capacitor C402 in parallel; the diode C405 is reversely connected with the diode D404 in parallel; the junction of the resistor R405 and the diode D405 is connected with the collector of the PNP triode Q403 through a diode D406; the base electrode of the PNP triode Q403 is connected with the second positive electrode of the driving power supply circuit through a resistor R406; the emitter of the PNP triode Q403 is connected with the second positive electrode of the driving power supply circuit through a resistor R407;

the collector of the NPN triode Q402 is connected with the base of the NPN triode Q404 through a resistor R410 and a diode D411 which are connected in sequence; the resistor R410 is connected with a capacitor C404 in parallel; the diode D412 is connected in parallel in the reverse direction with the diode D411; the junction of the resistor R410 and the diode D411 is connected with the collector of the NPN triode Q404 through the diode D410; the collector of the NPN triode Q404 is connected with the collector of the PNP triode Q403; an emitter of the NPN triode Q404 is connected with the second cathode of the driving power supply circuit through a resistor R411; the collector of the NPN triode Q404 is connected with the second negative electrode of the driving power supply circuit through a resistor R412; the collector of the NPN triode Q404 is connected with an IGBT switching tube of the modulation circuit. The benefits of this setup are: the switch has the advantages of small volume, high switching speed and strong shock resistance, and meets the design requirements of driving.

Preferably, the optical coupling isolation chip is an optical coupling isolation chip with the model number of HCPL-3120.

Preferably, the electric signal sampling feedback module comprises two output voltage and current sampling feedback circuits for respectively acquiring output voltage and current of the first direct current power supply and the second direct current power supply; the two output voltage and current sampling feedback circuits are respectively connected with the control system through the third isolator.

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

1. the utility model is suitable for a fast frequency pulse TIG welding power supply which adopts SiC power switch tube as main power device; the control system is connected with the SiC high-frequency drive circuit and the modulation switch tube drive circuit in a sampling isolation mode; the protection circuit has multiple protection functions, and can prevent the switch tube from being damaged while effectively driving the switch tube;

2. the utility model can inhibit the problems of over-high transient voltage and transient current and electromagnetic interference in the drive process of the SiC power switch tube, prevent the generation of voltage peak to cause false triggering, and has good drive effect;

3. the utility model discloses a high-speed high accuracy full digital control technique based on ARM, control accuracy is higher, and response speed is faster, has realized closed-loop control, changes in the design and the control that become more meticulous to fast pulse TIG electric arc, improves welding process quality.

Drawings

FIG. 1 is a schematic circuit diagram of a fast frequency pulse TIG welding power supply topology;

FIG. 2 is a system block diagram of the digital control circuit of the SiC-based fast frequency pulse TIG welding power supply of the present invention;

FIG. 3 is a circuit diagram of a SiC high frequency driving circuit in the digital control circuit of the SiC-based fast frequency pulse TIG welding power supply of the utility model;

FIG. 4 is a circuit diagram of a modulation switch tube driving circuit in the digital control circuit of the SiC-based fast frequency pulse TIG welding power supply of the present invention;

fig. 5 is the circuit diagram of the electric signal sampling feedback module in the digital control circuit of the SiC-based fast frequency pulse TIG welding power supply.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Examples

A topological circuit of the rapid frequency pulse TIG welding power supply is shown in figure 1 and comprises a first direct current power supply, a second direct current power supply and a modulation circuit.

As shown in FIG. 2, the utility model discloses SiC-based digital control circuit of fast-frequency pulse TIG welding power supply includes control system, electric signal sampling feedback module and drive module, can also include communication module and interface module. The driving module comprises a SiC high-frequency driving circuit and a modulation switching tube driving circuit; the control system is connected with the SiC high-frequency driving circuit through the first isolation circuit, and the SiC high-frequency driving circuit is respectively connected with the SiC power switch tubes of the first direct-current power supply and the second direct-current power supply so as to drive the SiC power switch tubes of the first direct-current power supply and the second direct-current power supply by the control system; the control system is connected with the modulation switching tube driving circuit through the second isolation switch, and the modulation switching tube driving circuit is connected with the IGBT switching tube of the modulation circuit so as to drive the IGBT switching tube of the modulation circuit by the control system; the control system is also connected with the electric signal sampling feedback module.

The utility model discloses control circuit's theory of operation is: the first direct current power supply converts 380V input alternating current into low-voltage smooth direct current, and then outputs the direct current to the modulation circuit. Two IGBT switching tubes in the modulation circuit are alternately switched at a frequency of 20kHz or more to convert the direct current into high-frequency pulse current. The high-frequency pulse current is superposed with the basic value direct current output by the direct current power supply II, and the fast-frequency pulse current is output to the external arc load. Sampling and feeding back the output voltage and current of a direct current power supply I and a direct current power supply II in a fast-frequency pulse TIG welding power supply to be independently controlled; output current and voltage are respectively collected at the output ends of the direct current power supply I and the direct current power supply II through the Hall sensors, the output current and voltage are input into the control system after signal conditioning, the control system compares an output value with a preset value, the output PWM duty ratio is changed, and closed-loop control is completed.

The utility model discloses control circuit uses control system as the core, combines peripheral hardware circuit to realize functions such as power welding flow task control, hardware circuit on-off control and signal of telecommunication feedback regulation and control, man-machine communication, striking. In the control circuit of the utility model, the SiC high-frequency drive circuit receives the PWM signal output by the control system, and realizes the drive control of the SiC power switch tube of the DC power supply I and the DC power supply II; and the modulation switching tube driving circuit receives the PWM signal output by the control system, and realizes the driving control of the IGBT switching tube of the modulation circuit, thereby regulating and controlling the output characteristic of the fast-frequency pulse TIG welding power supply. The electric signal sampling feedback module samples current and voltage, and inputs the current and voltage into the control system for digital filtering and PID control processing. The communication module comprises a human-computer interaction interface and robot communication, wherein the human-computer interaction interface is used for adjusting welding parameters and displaying output current and voltage and a welding state in real time; the robotic communication functions to set up the welding path and control the welding process.

The control system can adopt the prior art, for example, an ARM minimum control system is adopted, and the ARM minimum control system comprises a main control chip with the model number of STM32F405RGT6, a precision 3.3V power supply module, an external clock oscillation module, a reset module, a JTAG debugging interface and other auxiliary peripheral circuits. A FREERTOS system is embedded in the main control chip, so that real-time scheduling of multiple control tasks in the fast-frequency TIG welding power supply can be completed; the electric signal sampling feedback module is connected to an ADC port of the main control chip.

As shown in fig. 3, the control system is connected with the SiC high-frequency driving circuit through an isolation driving chip with a model number of ISO5451, and the isolation driving chip is further connected with a first driving power supply circuit; and the SiC high-frequency driving circuit is connected with SiC power switch tubes of the first direct-current power supply and the second direct-current power supply. The first driving power supply circuit can be composed of a DC-DC power supply with the model number QA121C2 and peripheral circuits thereof, and other existing power supply circuits can also be adopted.

The control system provides a PWM driving control signal, the control signal passes through the driving isolator after passing through the jitter removing circuit, and the isolated signal is output by the push-pull amplification of the rear-stage field effect transistor. The protection functions of the circuit design comprise short-circuit detection, Miller active clamping, under-voltage protection and the like, wherein the short-circuit detection DESAT generates a short-circuit protection signal through collecting the drain-source voltage of a SiC power switch tube and a comparator, an output driving signal is turned off through a logic circuit, and a resistor R310 and a diode D302 can prevent drain current from flowing backwards; the Miller active CLAMP CLAMP can monitor the grid voltage of the SiC power switch tube in real time, the voltage value of the SiC power switch tube is compared with a 2V reference voltage through a comparator and then is input into a logic circuit, and when the voltage exceeds 2V, a CLAMP field effect tube is started, so that the release of parasitic capacitance charges in a grid source electrode is facilitated, and the Miller effect is reduced or eliminated; under-voltage output locking UVLO can guarantee that when supply voltage is too low, can pull gate drive control signal to low level to make SiC power switch tube stop work.

The SiC high-frequency driving circuit comprises a capacitor C304, a capacitor C305, a voltage regulator tube ZD301, a diode D302, a diode D303, a resistor R310, a resistor R311, a resistor R312 and a resistor R313;

As shown in fig. 4, the control system is connected to the modulation switching tube driving circuit through the optical coupling isolation chip, and the modulation switching tube driving circuit is connected to the IGBT switching tube of the modulation circuit.

The modulation switching tube driving circuit comprises an NPN triode Q401, an NPN triode Q402, an NPN triode Q404, a PNP triode Q403 and a driving power supply circuit II;

the collector of the NPN triode Q402 is connected with the base of the NPN triode Q404 through a resistor R410 and a diode D411 which are connected in sequence; the resistor R410 is connected with a capacitor C404 in parallel; the diode D412 is connected in parallel in the reverse direction with the diode D411; the junction of the resistor R410 and the diode D411 is connected with the collector of the NPN triode Q404 through the diode D410; the collector of the NPN triode Q404 is connected with the collector of the PNP triode Q403; an emitter of the NPN triode Q404 is connected with the second cathode of the driving power supply circuit through a resistor R411; the collector of the NPN triode Q404 is connected with the second negative electrode of the driving power supply circuit through a resistor R412; the collector of the NPN triode Q404 is connected with an IGBT switching tube of the modulation circuit.

The control system and the modulation switch tube driving circuit are driven in an optical coupling isolation mode, the optical coupling is a high-speed optical coupling HCPL-3120 special for IGBT or MOSFET, the switching delay time is about 0.3us, and the high-speed optical coupling has small volume, high switching speed and strong impact resistance and can meet the driving design requirement. Because the modulation switch tube driving circuit generates two complementary driving electric signals without dead zones, the grid driving circuit structures of the two modulation IGBT switch tubes are the same, one of the two modulation IGBT switch tubes is intercepted, the isolation optocoupler is connected with a half-bridge topological structure formed by two MOSFETs, and finally, the +15V/-7V voltage is output to drive the modulation IGBT switch tube. The benefits of this setup are: the switch has the advantages of small volume, high switching speed and strong shock resistance, and meets the design requirements of driving.

The electric signal sampling feedback module comprises two paths of output voltage and current sampling feedback circuits for respectively acquiring output voltage and current of the first direct current power supply and the second direct current power supply; the two output voltage and current sampling feedback circuits are respectively connected with the control system through the third isolator. As shown in fig. 5, the output voltage and current sampling feedback circuit includes a 200A current hall sensor with model number HAS 200-P, an integrated differential amplifying circuit composed of a differential amplifier with model number AD629 and its peripheral circuits, and a low-pass filter circuit composed of a chip with model number OP177 and its peripheral circuits; the current Hall sensor, the integrated differential amplifying circuit and the low-pass filter circuit are connected in sequence.

The measurement voltage value converted back by the current hall sensor needs to be divided by resistors R501 and R502 and then connected to an integrated differential amplification circuit, wherein U501 is a differential amplifier AD629 with low offset, low gain error drift and high common mode rejection ratio, and the amplification factor is 1. Filtering is performed through a KRC active low-pass filter, a more flat Butterworth filter in a pass band is used as a model, wherein U502 is an operational amplifier OP177 with high precision and low zero drift, and the U502 is matched with the values of external resistance capacitors R503, R504, C505 and C506.

Compare with current welding power supply analog control method or classic control method that generally adopts at present, the utility model discloses directly adopted powerful, the low price single DSC level ARM microprocessor, the ARM in-chip solidification has the multi-functional digital wave control software system who runs in the embedded real-time operating system of FreeRTOS, can realize functions such as the production of PWM digital signal, state monitoring, the quick regulation and control of course of technology, all human-computer interactions also all realize through the touch-sensitive screen, the main circuit adopts wide band gap power device to carry out the contravariant current conversion.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to 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 SiC-based digital control circuit for a fast-frequency pulse TIG welding power supply comprises a first direct-current power supply, a second direct-current power supply and a modulation circuit; the method is characterized in that: the device comprises a control system, an electric signal sampling feedback module and a driving module; the driving module comprises a SiC high-frequency driving circuit and a modulation switching tube driving circuit; the control system is connected with the SiC high-frequency driving circuit through the isolation I, and the SiC high-frequency driving circuit is respectively connected with the SiC power switch tubes of the direct-current power supply I and the direct-current power supply II so as to drive the SiC power switch tubes of the direct-current power supply I and the direct-current power supply II by the control system; the control system is connected with the modulation switching tube driving circuit through the second isolation switch, and the modulation switching tube driving circuit is connected with the IGBT switching tube of the modulation circuit so as to drive the IGBT switching tube of the modulation circuit by the control system; the control system is also connected with the electric signal sampling feedback module.

2. The digital control circuit for a SiC-based fast frequency pulsed TIG welding power supply of claim 1, wherein: the control system is connected with the SiC high-frequency driving circuit through the isolation I, and the SiC high-frequency driving circuit is connected with SiC power switch tubes of the direct-current power supply I and the direct-current power supply II, and the control system is characterized in that:

3. The digital control circuit for a SiC-based fast frequency pulsed TIG welding power supply of claim 2, wherein: the SiC high-frequency driving circuit comprises a capacitor C304, a capacitor C305, a voltage regulator tube ZD301, a diode D302, a diode D303, a resistor R310, a resistor R311, a resistor R312 and a resistor R313;

a pin CLAMP of the isolation driving chip is connected with a grid electrode of the SiC power switch tube; the gate of the SiC power switch tube is grounded through a resistor R313 and a capacitor C305 which are connected in parallel; a pin OUT of the isolation driving chip is connected with a grid electrode of the SiC power switch tube through a resistor R312; the diode D303 and the resistor R311 are connected in series and then connected in parallel to the resistor R312; a pin OUT of the isolation driving chip is connected with a drain electrode of the SiC power switch tube through a resistor R310 and a diode D302 which are connected in series; the pin OUT of the isolation driving chip is also grounded through a capacitor C304 and a voltage stabilizing diode ZD301 which are connected in parallel; the terminal DESAT of the isolation driving chip is connected with the terminal OUT of the isolation driving chip.

4. The digital control circuit for a SiC-based fast frequency pulsed TIG welding power supply of claim 1, wherein: the control system is connected with the modulation switch tube driving circuit through the second isolation part, and the modulation switch tube driving circuit is connected with an IGBT switch tube of the modulation circuit, and the control system means that: the control system is connected with a modulation switching tube driving circuit through an optical coupling isolation chip, and the modulation switching tube driving circuit is connected with an IGBT switching tube of the modulation circuit.

5. The digital control circuit for a SiC-based fast pulse TIG welding power supply of claim 4, wherein: the modulation switching tube driving circuit comprises an NPN triode Q401, an NPN triode Q402, an NPN triode Q404, a PNP triode Q403 and a driving power supply circuit II;

6. The digital control circuit for a SiC-based fast pulse TIG welding power supply of claim 4, wherein: the optical coupling isolation chip is an optical coupling isolation chip with the model of HCPL-3120.

7. The digital control circuit for a SiC-based fast frequency pulsed TIG welding power supply of claim 1, wherein: the electric signal sampling feedback module comprises two paths of output voltage and current sampling feedback circuits for respectively acquiring output voltage and current of the first direct current power supply and the second direct current power supply; the two output voltage and current sampling feedback circuits are respectively connected with the control system through the third isolator.