Digital intelligent arc welding control system based on FPGA and STM32

Abstract

The invention discloses a digital intelligent arc welding control system based on FPGA and STM32, which comprises a power management module, a first control circuit and a second control circuit, and is characterized in that the first control circuit comprises an amplification filter circuit connected with output voltage and current of a welding power supply main circuit, a PWM output interface connected with a driver and an SPI interface communicated with the second control circuit; the second control circuit comprises an input interface connected with a welding gun and a cooling water tank controller, an output interface for controlling an air valve, a net pressure and temperature protection measurement and control circuit, an RS485 interface communicating with the UI operation panel and connected with a wire feeder controller, a CANBUS interface connected with the database interface board and the cooling water tank controller, and an SD card interface. Corresponding parameters are set from the UI operation panel, parameters such as output current, voltage and main inverter temperature are read from the welding power source main circuit, transient control over the current size and waveform is achieved, and finally welding performance control is achieved.

Description

Technical Field

[0001] The present invention relates to the field of intelligent welding, and particularly to a digital intelligent arc welding control system based on FPGA and STM32. Background Art

[0002] In the field of intelligent welding, with the rapid development of industrial automation and intelligent manufacturing, welding technology has been continuously advancing. Although existing welding equipment can achieve automated welding operations to a certain extent, there is still a large room for improvement in terms of digitization and intelligence. Welding equipment on the market can complete basic welding tasks, but often has problems such as insufficient control accuracy, inability to adjust welding parameters in real time and accurately, limited adaptability to different welding base materials and welding wires, etc. In addition, in the face of complex welding requirements and future intelligent development trends, existing welding equipment may be difficult to meet higher requirements. With the continuous progress of technology and the increasing requirements of industrial production for welding quality and efficiency, there is an urgent need in the market for a more digital and intelligent welding platform to better adapt to various welding working conditions, improve the accuracy and reliability of welding, and be able to continuously learn and evolve to lead the development direction of intelligent welding equipment. For example, in the development and application of SiC MOSFET, compared with Si MOSFET of the same power level, the on-resistance and switching losses of SiC MOSFET are significantly reduced, it is suitable for higher operating frequencies, and due to its high-temperature operating characteristics, its high-temperature stability is greatly improved.

[0003] Under this background, the digital intelligent welding platform of the present invention emerges as the times require, aiming to solve the deficiencies in the prior art and bring new breakthroughs and developments to the welding field.

[0004] An existing intelligent control method for TIG welding process (CN202310830413.1) includes an inverter power supply unit, a parameter setting unit, a real-time detection unit, a parameter processing unit, a pulse modulation unit and a control unit. The welding parameters are initially set and corrected through the parameter setting unit, and the trigger conditions for the voltage change threshold are set. The real-time detection unit continuously detects the real-time process parameter values of the welding parameters. The parameter processing unit and the control unit process the real-time process parameter values, calculate the welding voltage difference, current difference, power difference, and compare them with the preset parameters to determine whether to trigger the voltage or power change threshold. Thus, the consistency of the arc output ability is improved, tungsten electrode adhesion is avoided, and the weld appearance is improved. Summary of the Invention

[0005] The object of the present invention is to provide a digital intelligent arc welding control system based on FPGA and STM32. The welding platform sets corresponding parameters through the UI operation panel, and real-time collects process parameters such as output current, voltage, and main inverter temperature in the main circuit of the welding power supply, performs fast, accurate, and stable closed-loop response, realizes transient control of the current magnitude and waveform, and finally realizes the control of welding performance; reads relevant parameters in the database at the initial stage of welding, and can update the database according to the adjusted welding results, so as to establish a reliable expert database. Through the UI operation panel technical solution, a wired remote controller technology can be realized, the Linux / Android operating system is run, the voice input function is realized, the database stored in the server is queried through the HTTP protocol, data interaction is carried out with the on-site integrated controller, and a personalized database is established through account management. In addition, due to the need for a large number of parallel digital signal operations in a higher-precision welding process, the excellent parallel computing efficiency of the FPGA chip, high response speed, and accuracy can exceed traditional single-chip microcomputers and DSP chips.

[0006] The present invention is realized by at least one of the following technical solutions.

[0007] A digital intelligent arc welding control system based on FPGA and STM32 includes a power management module, a first control circuit, and a second control circuit. The first control circuit is provided with an FPGA processor chip, and the second control circuit is provided with an STM32F4 processor chip. The power management module is used to supply power to the first control circuit and the second control circuit;

[0008] The second control circuit sends welding setting parameters to the first control circuit through the SPI interface. The first control circuit sends two complementary PWMs to the SiC MOSFET driver through the PWM output interface, and drives the SiC MOSFET switch tube in the main circuit of the welding power supply through the SiC MOSFET driver. The first control circuit reads the voltage and current output by the main circuit of the welding power supply and returns them to the second control circuit through the SPI interface. The second control circuit sends the welding status information to the UI operation panel and updates the database.

[0009] Further, the first control circuit includes a current-voltage ADC interface circuit connected to the welding power supply, a PWM output interface connected to the SiC MOSFET driver circuit, an SPI interface connected to the second control circuit, and a spare expansion interface; the main control chip of the first control circuit adopts an FPGA processor chip of the GW2AR series based on the RISC-V architecture, and the ADC sampling pin of the FPGA processor chip is connected to the analog-to-digital conversion ADC chip, and the analog-to-digital conversion ADC chip is connected to the current-voltage ADC interface circuit.

[0010] Further, the second control circuit includes an input interface connecting the welding torch and the cooling water tank controller, an output interface for controlling the air valve, a line voltage and temperature protection measurement and control circuit, an RS485 interface connected to the isolated RS485 transceiver, a CANBUS interface connected to the database interface board and the cooling water tank controller, and an SD card interface connected to the SD card; the main control chip of the second control circuit uses the STM32F4 processor chip with a Cortex-M4 core. The RS485 pin of the STM32F4 processor chip is connected to the UI operation panel and the wire feeder controller through the isolated RS485 transceiver; the input and output pins of the main control chip are connected to the input and output interfaces of the second control circuit through the input and output interface circuit; the CAN pin of the main control chip is connected to the CANBUS interface of the second control circuit, and the second control circuit is connected to the SPI interface of the first control circuit.

[0011] Further, the FPGA processor chip adopts digital control and is connected to the SPI interface of the second control circuit through the SPI interface to realize data exchange, generate a peak current control mode PWM signal, a current slope compensation signal, and a peak current comparison signal, or a phase-shifted PWM signal and a low-spatter switch trigger signal, and detect the output voltage and current of the welding power supply. Then, according to the real-time current and voltage signals sent by the second control circuit through the SPI interface and the relevant set values sent by the UI panel through RS485, the frequency and duty cycle of the PWM signal are dynamically adjusted to realize the closed-loop control of the inverter main circuit of the welding power supply.

[0012] Further, the STM32F4 processor chip adopts digital control, sends the relevant parameters set by the UI operation panel to the SPI interface of the first control circuit through the SPI interface, and performs power status management according to the real-time current and voltage information of the main circuit of the welding power supply detected by the first control circuit, stores the basic welding parameter database, can download and update the welding database, realizes data exchange with the wire feeder, the cooling water tank, and the UI operation panel, and protects and alarms against abnormal line voltage and temperature and abnormal cooling water tank.

[0013] Further, the power management module includes a synchronous buck DC / DC converter, a step-down adjustable DC-DC power converter, an isolated DC-DC converter, and a step-down DC-DC adjustable power converter;

[0014] The model of the synchronous buck DC / DC converter is RT7272B, the input end is connected to +24V DC power, and the output is +15V DC power;

[0015] The model of the step-down adjustable DC-DC power converter is LM2576-15, the input end is connected to +24V DC power, and the output is -15V DC power;

[0016] The isolated DC-DC power converter model is LM2576-15, with its input terminal connected to +5V DC power, and the output is 3.3V DC power;

[0017] The buck DC-DC adjustable power converter model is MT3520B, with its input terminal connected to +5V DC power, and the output is 2.5V DC power.

[0018] Furthermore, the current and voltage pre-amplification filter module of the first control circuit uses a dual-channel 12-bit AD sampling chip to monitor the output voltage and current of the main circuit of the welding power supply. It compares the UI panel input values collected by the STM32F4 processor chip of the second control circuit through the RS485 interface with the output voltage and current of the main circuit of the welding power supply, so as to adjust the duty cycle of the PWM signal output by the first control circuit, and then drive the SiC MOSFET switch tube in the main circuit of the welding power supply, so that the actual current and voltage signals reach the set voltage and current signal values; Generate PWM signals through the peak current control mode, or generate phase-shifted PWM signals, and send relevant data to the SPI interface of the second control circuit through the SPI interface;

[0019] The first control circuit outputs two complementary PWM signals with adjustable duty cycles to the SiC MOSFET driver circuit through the PWM output interface, and changes the duty cycle and frequency of the two complementary PWM signals according to the welding setting parameters sent by the second control circuit through the SPI interface;

[0020] The first control circuit exchanges data with the second control circuit through the SPI communication interface, sends the collected voltage and current data to the second control circuit, and receives the working status such as the current welding setting parameters from the second control circuit.

[0021] Furthermore, the second control circuit compares the information received from the first control circuit with the information sent by the UI operation panel through RS485 communication, receives the data monitored by the cooling water tank controller through the CANBUS bus, and receives instructions to control the start and stop of the water pump motor;

[0022] The CANBUS interface circuit of the second control circuit uses an isolated CAN transceiver, connects to the database interface board through the CAN bus, and reads relevant data from the expert database during the welding process; After the welding is completed, the parameters are sent to the data interface board through the controller area network bus CANBUS to update the database;

[0023] The second control circuit monitors the abnormal working status of the water pump motor and the working status of the torch control circuit through the input interface and output interface circuit; Controls the opening and closing of the air valve through the output interface according to the working conditions;

[0024] The line voltage and temperature protection measurement and control circuit of the second control circuit is a voltage follower circuit composed of operational amplifiers. After the NTC voltage signal collected by the voltage follower circuit passes through a follower composed of FET input operational amplifiers, it is connected to the AD interface of the chip of the second control circuit and converted into a digital signal of 0-1024 to monitor the temperature of the main inverter and the process parameters of line voltage fluctuations;

[0025] The RS485 interface circuit for the second control circuit to communicate with the UI operation panel and connect to the wire feeder controller uses an isolated RS485 transceiver to distinguish the UI operation panel from the wire feeder by addressing; according to the welding voltage and current information sent by the first control circuit, corresponding control is performed on the gas valve and the wire feeder controller, and it is sent to the UI operation panel for display through the RS485 interface, so that the welding state can be displayed in real time. At the same time, the technical solution of this UI operation panel can realize the technology of a wired remote controller;

[0026] The second control circuit is connected to the wire feeder through an RS485 serial interface; the wire feeder uses a DC brushed motor drive mechanism, and the parameters of the motor are controlled through RS485; the voltages of the thermistors NTC1 and NTC2 are converted into analog quantities of 0-4095 and sampled through the line voltage and temperature protection measurement and control circuit at the ADC sampling interface on the STM32F4 processor chip of the second control circuit to realize temperature detection and overheat protection, and the signals of the torch switch and the abnormal cooling water tank are received through the input interface of the second control circuit;

[0027] The second control circuit realizes the connection with the SD card through the SD card interface of the STM32F4 processor chip, and stores the drawn current-voltage waveform in the SD card according to the collected voltage and current data sent by the first control circuit through the SPI communication interface.

[0028] Furthermore, the FPGA processor chip is GW2AR-LV18. GW2AR-LV18 is connected to the analog-to-digital conversion ADC chip through the ADC sampling pin, and then the ADC chip is connected to the current and voltage amplification filter module, connected to the PWM output interface through the chip IO port, and then the PWM output interface is connected to the SiC MOSFET driver circuit. It is connected to the SPI interface through the pins available for SPI communication on the GW2AR-LV18 chip, and then the SPI interface is connected to the SPI interface of the second control circuit;

[0029] The STM32F4 processor chip is STM32F407ZET6. STM32F407ZET6 is connected to the SPI interface of the first control circuit through the SPI interface to realize data exchange.

[0030] Furthermore, the second control circuit is connected and communicates with the UI operation panel through the RS485 serial interface; the UI operation panel is a controller that can be installed on the welding power supply panel or the wire feeder panel, and uses LEDs, digital tubes, or OLEDs for simple graphic display, and buttons / rotary encoders for operation; at the same time, the UI operation panel implements the wired remote controller technology, and can expand the WiFi / Bluetooth interface. The main control uses a single-chip SoC system and runs the Linux / Android operating system. The APP is compatible with mobile phone / tablet applications; the APP realizes the voice input function by calling the API of voice recognition; the APP can perform data interaction with the centralized controller through a socket connection to realize wireless remote operation of the welding equipment; a personalized database is established according to the actual welding situation, the database stored in the server is queried through the HTTP protocol, and data update is realized through account management.

[0031] Compared with the existing technologies, the beneficial effects of the present invention are as follows:

[0032] 1. The combination of digitization and intelligence: By combining the FPGA and STM32 processors, the present invention makes full use of the advantages of the chips to monitor and control parameters such as current and voltage during the welding process in real time, and interact with the UI operation panel and the database, providing more comprehensive control of the welding process; optimizing the welding parameters through the database reflects a higher level of intelligence; due to the combination of FPGA and STM32, the system has higher flexibility and scalability, realizing digital control and intelligent management during the welding process, and improving the welding accuracy and reliability.

[0033] 2. Real-time parameter adjustment: By collecting parameters such as current and voltage in the main circuit of the welding power supply in real time and performing closed-loop control, the real-time adjustment of welding parameters is realized.

[0034] 3. Establishment and update of the expert database: Read the parameters in the database at the initial stage of welding and update the database according to the welding results, establishing a reliable expert database, which improves the adaptability and intelligence level of welding.

[0035] 4. Remote upgrade and Internet connection: The programmable flexibility of the FPGA allows the chip to be remotely modified through a software upgrade package, and even remotely upgraded through the Internet, enhancing the scalability and maintainability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of a digital intelligent arc welding control system based on FPGA and STM32 in an embodiment of the present invention; Figure 2 It is a general structural block diagram of a digital intelligent arc welding control system based on FPGA and STM32 in an embodiment of the present invention; Figure 3 Schematic diagram of the current-voltage preamplification and filtering module circuit in the embodiment of the present invention; Figure 4 Schematic diagram of the peripheral circuit design of the AD sampling chip in the embodiment of the present invention; Figure 5 Real-time sampling waveform diagram of the ADC in the embodiment of the present invention; Figure 6 PWM output waveform diagram of the chip in the embodiment of the present invention; Figure 7 SPI data transmission waveform diagram of the second control circuit in the embodiment of the present invention; Figure 8 SPI data transceiver waveform diagram of the first control circuit in the embodiment of the present invention; Figure 9 Schematic diagram of the input-output interface circuit in the embodiment of the present invention; Figure 10 Schematic diagram of the network voltage temperature protection measurement and control circuit in the embodiment of the present invention; Figure 11 Schematic diagram of the RS485 interface circuit in the embodiment of the present invention; Figure 12 Schematic diagram of the SD card interface circuit in the embodiment of the present invention. Detailed implementation manners

[0049] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] Such as Figure 1As shown in the figure, a digital intelligent arc welding control system based on FPGA and STM32 in this embodiment includes a power management module, a first control circuit, and a second control circuit; the first control circuit is connected to the second control circuit through an SPI interface, and the first control circuit sends two complementary PWM signals to the SiC MOSFET driver, and the SiC MOSFET driver sends eight complementary AC signals to the main circuit of the welding power supply to control the SiC MOSFET in the main circuit, achieving the effect of controlling the output voltage and current waveforms.

[0051] As a preferred embodiment, in the power management module, the model of the synchronous buck DC / DC converter used to achieve 24 -> ±15V and 15 -> 5V is RT7272B; the model of the DC-DC power chip used to achieve 5V -> 3.3V is CA-IS3105W; the model of the buck DC-DC adjustable power chip used to achieve 5V -> 2.5V and 1V is MT3520B;

[0052] The power management module realizes multiple output DC voltages such as ±15V, 5V, 3.3V, 2.5V, and 1.0V from the input +24V DC power of the digital intelligent welding platform, so as to realize the function of supplying power or reference voltage for various control circuits and chips.

[0053] Specifically, the power management module includes a synchronous buck DC / DC converter, a buck adjustable DC-DC power converter, an isolated DC-DC converter, and a buck DC-DC adjustable power converter;

[0054] The model of the synchronous buck DC / DC converter is RT7272B. The input end of the RT7272B converter is connected to +24V DC power, and the output is +15V DC power, achieving 24 -> 15V and 15 -> 5V.

[0055] The chip model of the buck adjustable DC-DC power converter is LM2576-15. The input end of the LM2576-15 converter is connected to +24V DC power, and the output is -15V DC power, achieving 24 -> -15V.

[0056] The model of the isolated DC-DC power converter is LM2576-15. The input end of the LM2576-15 converter is connected to +5V DC power, and the output is 3.3V DC power, achieving 5 -> 3.3V.

[0057] The model of the buck DC-DC adjustable power converter is MT3520B. The input end of the MT3520B converter is connected to +5V DC power, and the output is 2.5V DC power, achieving 5 -> 2.5V.

[0058] As Figure 2As shown, the first control circuit includes a current-voltage ADC interface connected to a welding power source, a PWM output interface connected to a SiC MOSFET driver circuit, an SPI interface connected to a second control circuit, and a spare expansion interface. The main control chip of the first control circuit uses an FPGA processor chip. The ADC sampling pins of the main control chip are connected to an analog-to-digital conversion ADC chip, and the analog-to-digital conversion ADC chip is connected to the current-voltage ADC interface through a current-voltage amplification filter module.

[0059] The second control circuit includes an input interface connected to a welding torch and a cooling water tank controller, an output interface for controlling an air valve, a line voltage and temperature protection measurement and control circuit, an RS485 interface connected to an isolated RS485 transceiver, a CANBUS interface connected to a database interface board and a cooling water tank controller, and an SD card interface connected to an SD card. The main control chip of the second control circuit uses a Cortex-M4 core chip. The RS485 pins of the main control chip are connected to a UI operation panel and a wire feeder controller through an isolated RS485 transceiver. The input and output pins of the main control chip are connected to the input and output interfaces of the second control circuit through an input-output interface circuit. The CAN pins of the main control chip are connected to the CANBUS interface of the second control circuit through a CAN transceiver.

[0060] The control chip used in the first control circuit is a GW2AR series FPGA product (GW2AR-LV18), which supports the RISC-V architecture and is compatible with the RISC-V instruction set. This control chip is connected to an analog-to-digital conversion ADC chip through ADC sampling pins, and then the ADC chip is connected to a current-voltage amplification filter module. It is connected to a PWM output interface through the chip's IO ports, and then the PWM output interface is connected to a SiC MOSFET driver circuit. It is connected to an SPI interface through the pins available for SPI communication on the GW2AR-LV18 chip, and then the SPI interface is connected to the SPI interface of the second control circuit. Among them, the GW2AR-LV18 chip uses digital control, exchanges data with the second control circuit through the SPI interface, generates a peak current control mode PWM signal, a current slope compensation signal, and a peak current comparison signal, or a phase-shifted PWM signal, a low-spatter switch trigger signal, etc., and detects the output voltage and current of the welding power source. Then, it dynamically adjusts the frequency and duty cycle of the PWM signal according to the relevant set values sent by the second control circuit, thereby realizing the closed-loop control of the inverter main circuit of the welding power source.

[0061] The software platform uses Gowin FPGA Designer and can perform multitasking. The control chip used in the second control circuit is STM32F407ZET6, which is connected to the SPI interface of the first control circuit through the SPI interface to realize data exchange.

[0062] As Figure 3 shown in (a) and (b) of Figure 3 , the current-voltage ADC interface is connected to the output end of the main circuit of the welding power source, where a DC voltage signal of 0 - 50V is input into Figure 3 the UF+ and UF- ports in Figure 3 . After passing through the voltage-dividing circuit composed of resistors R100 and R105 and the amplifying circuit composed of operational amplifiers (IC16, IC18), a DC voltage of 0 - 3.3V is output from Figure 3 the ADC1 port in Figure 3 and connected to the ADC1 pin of the analog-to-digital conversion ADC chip of the first control circuit.

[0063] After the current signal of 0 - 400A passes through a 400A / 3.3V Hall sensor, a DC voltage of 0 - 3.3V is input at the LEM400 port in Figure 3 Figure 3 . After passing through the voltage-following circuit composed of an operational amplifier, a DC voltage of 0 - 3.3V is output from the ADC2 port and connected to the ADC1 pin of the analog-to-digital conversion ADC chip of the first control circuit.

[0064] As Figure 4 shown, in this embodiment, the analog-to-digital conversion chip ADC of the first control circuit selects a 12-bit dual-channel AD7356 analog-to-digital converter, which can accurately sample the current and voltage, and thus can accurately and quickly sample the current and voltage in the real-time welding process. The model of the analog-to-digital conversion chip ADC used in the current-voltage amplifier filter module in the first control circuit is AD7356YRUZ. The 1st and 2nd pins VINA- and VINA+ of this analog-to-digital conversion chip are the analog input terminals of sampling channel 1; the 3rd and 6th pins are the decoupling capacitor pins for the reference voltage; the 4th pin is the reference ground of the reference voltage; the 5th and 11th pins are the analog ground; the 7th and 8th pins VINB- and VINB+ are the analog input terminals of sampling channel 2; the 9th pin is the power input; the 10th pin is the chip select pin of the chip, where a low level represents a valid logic input; the 12th pin is the digital ground; the 13th and 14th pins SDATAB and SDATAA are respectively the serial data output interfaces of the digital quantities after the signals of sampling channel 2 and sampling channel 1 are converted, and the data output is sent to the control chip of the first control circuit in the form of a serial data stream; the 15th pin is the clock output, connected to the control chip of the first control circuit; the 16th pin is the power input. In this embodiment, the reference voltage is set to 3.3V, so the sampling output range of this analog-to-digital conversion chip is -3.3 to +3.3V. In this embodiment, the input pins 1 (VINA+) and 8 (VINB+) of the analog-to-digital conversion chip are respectively connected to the ADC1 and ADC2 ports. The analog-to-digital conversion ADC chip converts the 0 - 3.3V analog signals output from the ADC1 and ADC2 ports into 12-bit digital signals, which are output from the pins 14 (SDATAA) and 13 (SDATBB) to the ADC sampling pins of the main control chip of the first control circuit.

[0065] As a preferred embodiment, to ensure the sampling accuracy, the sampling rates of the two channels (A and B) of the analog-to-digital conversion chip ADC are set to 5 MSPS, with no conversion delay, and the sampling clock period is set to 12.5 ns (80 MHz), achieving data conversion and data reading within 200 ns. Taking channel A as an example, when the input voltage is 2.5 V, the real-time sampling waveform diagram and data are as Figure 5 shown. The sampled data of sampling channel A is (3747), corresponding to its input voltage.

[0066] The PWM output interface outputs a PWM signal with adjustable pulse width, which is used to adjust the primary inverter output of the welding power supply. By modulating the pulse width, the magnitude of the output voltage is changed, thereby adjusting the amplitude of the voltage output. The FPGA control chip of the first control circuit outputs two complementary PWM signals (PWM1 and PWM2 signals) from the PWM output interface through timing. The schematic diagram of the waveform output by the control chip is as Figure 6 shown, where the high level is +3.3 V and the low level is 0 V. The dead time of the PWM1 and PWM2 signals is set to 200 ns. In this embodiment, the duty cycles of PWM1 and PWM2 are 32.60% and 33.34% respectively, and the dead time is inserted when PWM1 is turned off or PWM2 is turned off.

[0067] The SPI interface is responsible for realizing the data exchange between the first control circuit and the second control circuit, sending the collected voltage and current data to the second control circuit, and receiving the relevant set welding parameters sent by the second control circuit. The control chip STM32F407 of the second control circuit and the control chip GW2AR-LV18 of the first control circuit adopt the SPI communication protocol in the master-slave mode, with GW2AR-LV18 as the master and STM32F407 as the slave. As the master, GW2AR-LV18 provides the SPI communication clock and selects the slave device. STM32F407 does not generate a control clock signal. In this embodiment, STM32F407 sends 16-bit data to test the SPI communication. The waveform of data transmission and reception measured by the oscilloscope is as Figure 7 shown, and the transmitted data is 0001001101010111.

[0068] As Figure 8As shown in (a), (b), and (c) of this embodiment, the transistor output optocoupler chip model used in the input / output interface circuit is HCRN201-500E; in the input interface and output interface of the second control circuit, the output ports of the torch control circuit and the output port of the cooling water tank controller are connected to the input pins of the first control circuit through the input interface circuit, so as to realize the abnormal alarm of the cooling water tank and the monitoring of the torch state. The output pins of the first control circuit are connected to the input port of the gas valve control circuit through the output interface circuit, which is responsible for realizing the on / off control of the gas valve. The second control circuit monitors the abnormal working state of the water pump motor and the working state of the torch control circuit through the input / output interface circuit; controls the gas valve switch according to the working condition through the output interface. When the output port outputs a high level, Figure 8 the voltage of pin 1 of the optocoupler chip IC11 in the output interface circuit is greater than the voltage of pin 2 of the optocoupler chip IC11, so pins 15 and 16 of the optocoupler chip IC11 are turned on. Figure 8 a current signal is detected at the base of the triode Q1 in it, and it satisfies that the base voltage of the triode Q1 is greater than the emitter voltage of the triode Q1. The triode Q1 conducts as a switching tube, so that Figure 8 a low level is output at the GAS interface in it. The GAS interface is connected to the input port of the gas valve control circuit, so as to realize the on / off control of the gas valve; when Figure 8 a low level is detected at the input signal COOLER-ERR terminal of the input interface circuit in it, Figure 8 the voltage of pin 1 of the transistor output optocoupler chip IC8 is greater than the voltage of pin 2 in it, and pins 16 and 15 of the optocoupler chip IC8 are turned on. At this time, Figure 8 a low level is output from the PE4 port to the input pin of the first control circuit in it; similarly, when Figure 8 a low level is detected at the input signal TORCH terminal of the input interface circuit in it, the voltage of pin 5 of the transistor output optocoupler chip IC8 is greater than the voltage of pin 6, and pins 12 and 11 of the transistor output optocoupler chip IC8 are turned on. At this time, Figure 8 a low level is output from the PE6 port to the input pin of the first control circuit in it.

[0069] As Figure 9 shown, the line voltage temperature protection measurement and control circuit is composed of a voltage follower circuit formed by an operational amplifier. The model of the operational amplifier used in this embodiment is LF347D. Figure 9The input ports NTC1 and NTC2 are respectively connected to the thermistors NTC1 and NTC2, and the input port V-PRIM interface is connected to the signal after the grid voltage is divided. The output ports ADC2_IN13, ADC2_IN14, and ADC2_IN15 are connected to the ADC sampling pins of the main control chip of the second control circuit. Among them, the thermistors NTC1 and NTC2 are respectively connected to the inverter circuit in the main circuit of the welding power supply. The input ends NTC1 and NTC2 are used to detect the voltages of NTC1 and NTC2 in the circuit. The voltages at the NTC1 and NTC2 ports are output to the ADC2_IN13 and ADC2_IN14 ports after passing through the voltage follower composed of an operational amplifier, and are connected to the ADC sampling pins of the main control chip of the second control circuit, so as to realize the detection of the voltages at both ends of the NTC1 and NTC2 thermistors. Since the NTC is a negative temperature coefficient thermistor, its main functions include: temperature measurement, temperature compensation, and current limiting protection. According to the characteristics of the NTC, the temperature of the current inverter is calculated to realize temperature monitoring. The V-PRIM interface outputs the divided grid voltage to the ADC2_IN15 port after passing through the voltage follower composed of an operational amplifier, and is connected to the ADC sampling pin of the main control chip of the second control circuit to sample the fluctuations of the current grid voltage in real time, so as to achieve the effect of monitoring the grid voltage fluctuations

[0070] As Figure 10 shown, the isolation type RS485 transceiver adopted by the second control circuit is model CA-IS3092W; the RS485 interface realizes the communication between the second control circuit and the UI operation panel and the wire feeder controller through the isolation type RS485 transceiver, and is distinguished by the address bit in the communication data. The transceiver chip of the isolation type RS485 transceiver has its pin 1 connected to the power supply, pins 2, 7, and 8 grounded, pin 3 is the receiver output end, pin 4 is the receiver enable control, low level is valid; pin 5 is the transmitter enable control: high level is valid; pin 6 is the transmitter data input end. When DE is at a high level, if DI is at a high level, then A outputs a high level and B outputs a low level; pins 9 and 15 are the ground on the bus side; when pin 10 is grounded, VISO = 3.3V at pin 16; pin 12 is the receiver non-inverting input / transmitter non-inverting output end; pin 13 is the receiver inverting input / transmitter inverting output end; among them, pins 3, 5, and 6 are connected to the control chip of the second control circuit, and pins 12 and 13 are respectively connected to the RS485 interfaces of the UI operation panel and the wire feeder controller. In this embodiment, pins 3 and 6 of the isolation type RS485 transceiver chip are respectively connected to the RS485 pins of the main control chip of the second control circuit, pins 4 and 5 of the RS485 transceiver chip are connected to the enable RS485 pins of the main control chip of the second control circuit, and pins 12 and 13 of the RS485 transceiver chip are respectively connected to the RS485 receiving and sending pins of the UI panel and the wire feeder controller

[0071] As shown Figure 11 in the figure, the isolation type CAN transceiver adopted by the second control circuit is CA-IS3062W; the CANBUS interface communicates with the database interface board and the cooling water tank controller through the isolation type CAN transceiver, receives the data monitored by the cooling water tank controller through the CANBUS bus, and thus receives commands to control the start and stop of the water pump motor; reads relevant data from the expert database during the welding process. The pin 1 of the chip of this isolation type CAN transceiver is the power input; the pins 2 and 8 are the logic side grounds; the pin 3 is the driver input data; the pins 4, 6, 7, and 14 are not connected; the pin 5 is the receiver output data; the pins 9, 10, and 15 are the bus side grounds; the pins 11 and 16 are the bus side isolated power outputs; the pin 12 is the low-level CAN voltage input / output; the pin 13 is the high-level CAN voltage input / output. In this embodiment, the pins 3 and 5 of the isolation type CAN transceiver chip are respectively connected to the CAN pins of the main control chip of the second control circuit, and the pins 12 and 13 of the CAN transceiver chip are respectively connected to the receive and transmit pins of the CAN bus.

[0072] As shown Figure 12 in the figure, the SD card interface circuit is used to save the waveforms drawn during the welding process. The IO port on the main control chip of the second control circuit is multiplexed as the interface connected to the SD card. The pins 7, 8, 9, and 1 of the SD card adopted in this embodiment are data D0 - D3 respectively, and the pin 2 is used to transmit command signals; the pins 3 and 11 are grounded; the pins 4 and 6 are connected to the power supply; the pin 5 is connected to the clock signal for synchronizing data transmission; the pins 10, 11, and 12 are floating; in this embodiment, the pins 7, 8, 9, and 1 of the SD card are respectively connected to the SD card connection pins of the main control chip of the second control circuit, the pin 5 of the SD card is connected to the SD card clock pin of the main control chip of the second control circuit, and the pin 2 of the SD card is connected to the SD card transmission command pin of the main control chip of the second control circuit.

[0073] The second control circuit is connected and communicates with the UI operation panel through an RS485 serial interface; the UI operation panel is a controller that can be installed on the welding power supply panel or the wire feeder panel, and uses LEDs, digital tubes, or OLEDs for simple graphic display, and buttons / rotary encoders for operation. In this embodiment, after the operator inputs parameters such as the welded base material, wire type, and welding method on the UI operation panel, the UI operation panel sends data to the second control circuit through RS485 serial communication. The second control circuit reads the database through the CANBUS bus and then sends data to the first control circuit through the SPI interface. The first control circuit participates in the PID operation with the voltage and current signals output by the welding power supply main circuit sampled by the AD sampling chip with this parameter, and dynamically outputs the frequency and duty cycle of two complementary PWMs, thereby realizing the closed-loop control of the voltage and current during the welding process, and sending two complementary PWMs to the SiC MOSFET driver through the PWM output interface, and controlling the SiC MOSFET switching tubes in the welding power supply main circuit through the SiC MOSFET driver; the first control circuit samples and reads the voltage and current output by the welding power supply main circuit through the amplifier filter circuit, and sends data to the second control circuit through the SPI interface. The second control circuit controls the wire feeding of the wire feeder, controls the opening and closing of the air valve according to the working conditions, sends the welding state information to the UI operation panel, and updates the database, so as to be able to display the welding state and the voltage and current waveforms during the welding process in real time on the UI operation panel, realize the transient control of the current magnitude and waveform, and finally realize the control of the welding performance and establish a reliable expert database.

[0074] A digital intelligent arc welding control system based on FPGA and STM32 of the present invention helps to operate the equipment more simply, correctly, and quickly, and improves the welding quality. The UI operation panel is used to set parameters and detect welding data. Through the set parameters and real-time monitoring during the welding process, the welding state can be displayed in real time. The display of the welding current and voltage waveforms is newly added, and the waveform changes can be observed during the welding process.

[0075] Reliable data in the database is read at the initial stage of welding, combined with the sampling and monitoring of the current and voltage parameters during the welding process, the welding state is monitored in real time and the welding process parameters are dynamically adjusted, realizing the real-time update and processing of the parameters during the welding process, thereby updating the database and making the database more reliable.

[0076] Obviously, the above embodiments are only examples given for clear illustration, rather than limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A digital intelligent arc welding control system based on FPGA and STM32, characterized in that, It includes a power management module, a first control circuit, and a second control circuit. The first control circuit is provided with an FPGA processor chip, and the second control circuit is provided with an STM32F4 processor chip. The power management module is used to supply power to the first control circuit and the second control circuit; The second control circuit sends welding setting parameters to the first control circuit through the SPI interface. The first control circuit sends two complementary PWMs to the SiC MOSFET driver through the PWM output interface, and drives the SiC MOSFET switch tube in the main circuit of the welding power supply through the SiC MOSFET driver. The first control circuit reads the voltage and current output by the main circuit of the welding power supply and returns them to the second control circuit through the SPI interface. The second control circuit sends the welding status information to the UI operation panel and updates the database.

2. The digital intelligent arc welding control system based on FPGA and STM32 according to claim 1, wherein The first control circuit includes a current-voltage ADC interface circuit connected to the welding power supply, a PWM output interface connected to the SiC MOSFET driver circuit, an SPI interface connected to the second control circuit, and a spare expansion interface; the main control chip of the first control circuit uses an FPGA processor chip of the GW2AR series based on the RISC-V architecture. The ADC sampling pin of the FPGA processor chip is connected to the analog-to-digital conversion ADC chip, and the analog-to-digital conversion ADC chip is connected to the current-voltage ADC interface circuit.

3. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 1, characterized in that, The second control circuit includes an input interface connected to the welding torch and the cooling water tank controller, an output interface for controlling the air valve, a network voltage and temperature protection measurement and control circuit, an RS485 interface connected to the isolated RS485 transceiver, a CANBUS interface connected to the database interface board and the cooling water tank controller, and an SD card interface connected to the SD card; the main control chip of the second control circuit uses an STM32F4 processor chip with a Cortex-M4 core. The RS485 pin of the STM32F4 processor chip is connected to the UI operation panel and the wire feeder controller through the isolated RS485 transceiver; the input and output pins of the main control chip are connected to the input and output interfaces of the second control circuit through the input and output interface circuit; the CAN pin of the main control chip is connected to the CANBUS interface of the second control circuit through the CAN transceiver, and the second control circuit is connected to the SPI interface of the first control circuit.

4. The digital intelligent arc welding control system based on FPGA and STM32 according to claim 2, wherein The FPGA processor chip uses digital control and is connected to the SPI interface of the second control circuit through the SPI interface to achieve data exchange, generate a peak current control mode PWM signal, a current slope compensation signal, and a peak current comparison signal, or a phase-shifted PWM signal and a low-spatter switch trigger signal, and detect the output voltage and current of the welding power supply. Then, according to the real-time current and voltage signals sent by the second control circuit through the SPI interface and the relevant set values sent by the UI panel through RS485, the frequency and duty cycle of the PWM signal are dynamically adjusted to achieve the closed-loop control of the main circuit of the welding power supply inverter.

5. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 3, characterized in that, The STM32F4 processor chip adopts digital control, sends the relevant parameters set by the UI operation panel to the SPI interface of the first control circuit through the SPI interface, and performs power status management according to the real-time current and voltage information of the main circuit of the welding power supply detected by the first control circuit. It stores a basic welding parameter database, can download and update the welding database, realizes data exchange with the wire feeder, cooling water tank, and UI operation panel, and protects and alarms against abnormal network voltage temperature and abnormal cooling water tank.

6. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 1, characterized in that The power management module includes a synchronous buck DC / DC converter, a buck-type adjustable DC-DC power converter, an isolated DC-DC converter, and a buck-type DC-DC adjustable power converter; The model of the synchronous buck DC / DC converter is RT7272B, the input end is connected to +24V DC power, and the output is +15V DC power; The model of the buck-type adjustable DC-DC power converter is LM2576-15, the input end is connected to +24V DC power, and the output is -15V DC power; The model of the isolated DC-DC power converter is LM2576-15, the input end is connected to +5V DC power, and the output is 3.3V DC power; The model of the buck-type DC-DC adjustable power converter is MT3520B, the input end is connected to +5V DC power, and the output is 2.5V DC power.

7. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 2, characterized in that The current and voltage pre-amplification filter module of the first control circuit uses a dual-channel 12-bit AD sampling chip to monitor the output voltage and current of the main circuit of the welding power supply. It compares the UI panel input value collected by the STM32F4 processor chip of the second control circuit through the RS485 interface with the output voltage and current of the main circuit of the welding power supply, so as to adjust the duty cycle of the PWM signal output by the first control circuit, and then drive the SiC MOSFET switch tube in the main circuit of the welding power supply, so that the actual current and voltage signal reaches the set voltage and current signal value; Generate a PWM signal through the peak current control mode, or generate a phase-shifted PWM signal, and send the relevant data to the SPI interface of the second control circuit through the SPI interface; The first control circuit outputs two complementary PWM signals with adjustable duty cycles to the SiC MOSFET driver circuit through the PWM output interface, and changes the duty cycle and frequency of the two complementary PWM signals according to the welding setting parameters sent by the second control circuit through the SPI interface; The first control circuit exchanges data with the second control circuit through the SPI communication interface, sends the collected voltage and current data to the second control circuit, and receives the current welding setting parameters and other working states from the second control circuit.

8. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 3, characterized in that, The second control circuit compares the information received from the first control circuit with the information sent by the UI operation panel through RS485 communication, receives the data monitored by the cooling water tank controller through the CANBUS bus, and receives instructions to control the start and stop of the water pump motor; The CANBUS interface circuit of the second control circuit uses an isolated CAN transceiver, connects to the database interface board through the CAN bus, and reads relevant data from the expert database during the welding process; after welding, it sends parameters to the data interface board through the Controller Area Network bus CANBUS to update the database; The second control circuit monitors the abnormal working state of the water pump motor and the operation of the torch control circuit through the input interface and output interface circuit; Controls the air valve switch according to the working conditions through the output interface; The line voltage and temperature protection measurement and control circuit of the second control circuit is a voltage follower circuit composed of operational amplifiers. The voltage follower circuit connects the collected NTC voltage signal to the chip AD interface of the second control circuit after passing through a follower composed of FET input operational amplifiers, and converts it into a digital signal of 0 - 1024 to monitor the main inverter temperature and line voltage fluctuation process parameters; The communication between the second control circuit and the UI operation panel and the RS485 interface circuit connecting to the wire feeder controller use isolated RS485 transceivers, and distinguish the UI operation panel and the wire feeder through the addressing method; according to the welding voltage and current information sent by the first control circuit, it controls the gas valve and the wire feeder controller accordingly, and sends it to the UI operation panel for display through the RS485 interface, so that the welding state can be displayed in real time. At the same time, adopting this UI operation panel technical solution can realize the wired remote controller technology; The second control circuit is connected to the wire feeder through the RS485 serial interface; the wire feeder adopts a DC brush motor drive mechanism, and the parameters of the motor are controlled through RS485; the voltages of the thermistors NTC1 and NTC2 are converted into 0 - 4095 analog quantities, and are sampled through the line voltage and temperature protection measurement and control circuit connected to the ADC sampling interface on the STM32F4 processor chip of the second control circuit to realize temperature detection and overheat protection, and the signals of the torch switch and the abnormal cooling water tank are received through the input interface of the second control circuit; The second control circuit realizes the connection with the SD card through the SD card interface of the STM32F4 processor chip, and stores the drawn current - voltage waveform to the SD card according to the collected voltage and current data sent by the first control circuit through the SPI communication interface.

9. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 2, wherein, The FPGA processor chip is GW2AR - LV18. GW2AR - LV18 is connected to the analog - to - digital conversion ADC chip through the ADC sampling pin, and then the ADC chip is connected to the current - voltage amplification and filter module, connected to the PWM output interface through the chip IO port, then the PWM output interface is connected to the SiC MOSFET driver circuit, connected to the SPI interface through the pins available for SPI communication on the GW2AR - LV18 chip, and then the SPI interface is connected to the SPI interface of the second control circuit; The STM32F4 processor chip is STM32F407ZET6. STM32F407ZET6 is connected to the SPI interface of the first control circuit through the SPI interface to realize data exchange.

10. A digital intelligent arc welding control system based on FPGA and STM32 according to claim 5, characterized in that, The second control circuit is connected and communicates with the UI operation panel through the RS485 serial interface; the UI operation panel is a controller that can be installed on the welding power source panel or the wire feeder panel, and uses LED, digital tube or OLED for simple graphic display, and is operated by buttons / rotary encoders; at the same time, the UI operation panel realizes the technology of a wired remote controller, can expand the WiFi / Bluetooth interface, the main control uses a single-chip SoC system, runs the Linux / Android operating system, and the APP can be compatible with mobile phone / tablet applications; the APP realizes the voice input function by calling the API of voice recognition; the APP can perform data interaction with the centralized controller through a socket connection to realize the wireless remote operation of the welding machine equipment; a personalized database is established according to the actual welding situation, the database stored in the server is queried through the HTTP protocol, and data update is realized through account management.

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