Medium-frequency induction heating power supply for bolt heating

Abstract

The utility model relates to a medium-frequency induction heating power supply for bolt heating. The medium-frequency induction heating power supply comprises a main circuit and a control circuit, the main circuit is used for converting a three-phase alternating current into a medium-frequency alternating current and driving an induction heating load; the control circuit is used for realizing intelligent control and protection of the power supply; the main circuit comprises a rectifier bridge BD1, a buffer porcelain tube resistor R4, an electric reactor L0, an IGBT module, a shunt R6, an intermediate frequency transformer TR1, an intermediate frequency transformer TR2, a resonant capacitor bank C6, a resonant capacitor bank C10 and an induction heating load. And the IGBT module comprises an IGBT (Insulated Gate Bipolar Translator) 1, an IGBT 2, an IGBT 3 and an IGBT 4. The utility model has the advantages that the one-driving-two structure saves cost and space, the main circuit adopts the one-driving-two structure, one main circuit can drive two control circuits, compared with the traditional single-path control structure, the cost can be effectively saved, the equipment volume is reduced, the installation and the arrangement are convenient, and the bolt heating device is suitable for the bolt heating application scene with limited space.

Description

Technical Field

[0001] This utility model relates to a medium-frequency induction heating power supply for heating bolts, belonging to the field of induction heating power supplies. Background Technology

[0002] Bolt heating is a common process in industry, currently mainly using flame heating and resistance heating rods. However, these two traditional heating methods have many shortcomings:

[0003] 1. Flame heating method: This method uses an open flame and has disadvantages such as low heating efficiency, harsh working environment for operators, poor safety, and inability to monitor temperature. This heating method not only has low energy efficiency but also requires highly skilled operators, making it prone to safety accidents due to improper operation.

[0004] 2. Resistance heating rod method: This is a type of conduction heating, which also faces the problems of low heating efficiency and long heating time. In addition, its control system is complex and lacks flexibility, making it difficult to meet the high requirements of heating precision and efficiency in modern industrial production.

[0005] With technological advancements, digitally controlled induction heating power supplies have been widely applied in various industries. However, due to the unique characteristics of bolt heating devices and transformers, the application of induction heating power supplies in bolt heating started relatively late. Nevertheless, existing induction heating power supplies still present some challenges in bolt heating applications, such as unstable control, large size, and insufficient signal feedback. These issues limit the further promotion and application of induction heating power supplies in the bolt heating field.

[0006] Therefore, developing an induction heating power supply for bolt heating that can overcome the shortcomings of the existing technology is of great practical significance and has broad market prospects. Utility Model Content

[0007] To overcome the shortcomings of existing technologies, this utility model provides a medium-frequency induction heating power supply for bolt heating. The technical solution of this utility model is as follows:

[0008] A medium-frequency induction heating power supply for bolt heating includes a main circuit and a control circuit. The main circuit converts three-phase AC power into medium-frequency AC power to drive the induction heating load. The control circuit enables intelligent control and protection of the power supply. The main circuit includes a rectifier bridge BD1, a buffer ceramic tube resistor R4, a reactor L0, an IGBT module, a shunt R6, a medium-frequency transformer TR1, a medium-frequency transformer TR2, a resonant capacitor bank C6, a resonant capacitor bank C10, and the induction heating load. The IGBT module includes IGBT1... IGBT2, IGBT3, and IGBT4; external three-phase AC power is connected to rectifier bridge BD1 after passing through molded case circuit breaker QF. A high-frequency filter capacitor C1 is connected in parallel across rectifier bridge BD1. The positive terminal of the rectified DC voltage output is connected to one end of buffer ceramic tube resistor R4. The main contacts of the AC contactor are connected in parallel across R4. The other end of resistor R4 is connected to one end of reactor L0. The other end of reactor L0 is connected to the positive terminals of IGBT1, IGBT2, IGBT3, and IGBT4. The negative terminals of IGBTs 3 and 4 return to the negative terminal of the rectifier bridge BD1 via shunt R6. The output terminal of IGBT 1 is connected to one end of the primary winding of the intermediate frequency transformer TR1. The output terminal of IGBT 2 is connected to the other end of the primary winding of transformer TR1 via DC blocking capacitor C5. The output terminal of IGBT 3 is connected to one end of the primary winding of the intermediate frequency transformer TR2. The output terminal of IGBT 4 is connected to the other end of the primary winding of transformer TR2 via DC blocking capacitor C9. Absorption capacitors C3 and C4 are connected in parallel between IGBTs 1 and 2. IGBT3 and IGBT4 are connected in parallel with absorption capacitors C7 and C8. A filter capacitor bank C2 is connected in parallel between the reactor L0 and the negative terminal of the IGBT module. One end of the secondary side of transformer TR1 is connected to the resonant capacitor bank C6. The other end of the resonant capacitor bank C6 is connected to the induction heating load. The other end of the induction heating load is connected back to the secondary side of transformer TR1. One end of the secondary side of transformer TR2 is connected to the resonant capacitor bank C10. The other end of the resonant capacitor bank C10 is connected to the induction heating load. The other end of the load is connected back to the secondary side of transformer TR2.

[0009] In the main circuit, the three output terminals of the molded case circuit breaker QF are each connected to a sampling resistor, namely sampling resistor R1, sampling resistor R2, and sampling resistor R3. The output terminals of the molded case circuit breaker QF are connected to the main control board U1 and main control board U2 through sampling resistors R1, R2, and R3 to obtain the three-phase AC voltage. The rear end of the reactor L0 is connected to the main control board U1 and main control board U2 through sampling resistor R5 to obtain the DC bus voltage. The two ends of the shunt R6 are connected to the main control board U1 and main control board U2 to obtain the bus current. A current transformer CT1 is fitted onto the output connection line of IGBT1; a current transformer CT2 is fitted onto the output connection line of IGBT3. The output of current transformer CT1 is connected to the main control board U1, and the output of current transformer CT2 is connected to the main control board U2, for obtaining the resonant output current; the two ends of resonant capacitor C6 are connected to voltage transformer VT1; the two ends of resonant capacitor C10 are connected to voltage transformer VT2. The output of voltage transformer VT1 is connected to the main control board U1, and the output of voltage transformer VT2 is connected to the main control board U2, for obtaining the resonant output voltage.

[0010] The three output terminals of the molded case circuit breaker QF are connected to the fan FAN via AC contactor KM3; one output terminal of the molded case circuit breaker QF and the input neutral wire are connected to the input terminal of the switching power supply P1, which outputs 24V+ and GND to power the control circuit.

[0011] The control circuit includes a signal acquisition and control circuit and a main control system. The signal acquisition and control circuit is connected to the main control system. The main control system includes a main control board, an LCD screen, and a driver board. The driver board amplifies the PWM signal sent from the main control board and drives the IGBT module to output the inverter. The LCD screen communicates with the ARM of the main control board via RS232 or RS485.

[0012] The signal acquisition and control circuit includes a power indicator HL1, a running indicator HL2, an alarm indicator HL3, a running indicator HL4, an alarm indicator HL5, a power indicator HL1, control switches K1, K2, K3, K4, and K5, a start / stop switch SB1, a start / stop switch SB2, and an emergency stop switch SB3. One end of the power indicator HL1 is connected to GND, and the other end is connected to 24V+. One end of the running indicator HL2 is connected to 24V+, and the other end is connected to GND via control switch K1. One end of the alarm indicator HL3 is connected to 24V+, and the other end is connected to GND via control switch K2. One end of indicator light HL4 is connected to 24V+, and the other end is connected to GND via control switch K3; one end of alarm indicator light HL5 is connected to 24V+, and the other end is connected to GND via control switch K3; control switches K1 and K2 are both controlled by the main control board U1; one end of the coil of fan relay K6 is connected to 24V+, and the other end is connected to GND via control switch K5; one end of start / stop switch SB1 is connected to 24V+, and the other end is connected to the main control board U1; one end of start / stop switch SB2 is connected to 24V+, and the other end is connected to the main control board U2; one end of emergency stop switch SB3 is connected to 24V+, and the other end is connected to both the main control board U1 and the main control board U2.The main control boards U1 and U2 have the same structure, both including an ARM1 control unit and an ARM2 control unit. The ARM1 control unit is used for processing AC voltage, temperature, and I / O signals; the ARM2 unit is used for acquiring and calculating resonant output current and voltage, as well as processing PWM output. The ARM1 and ARM2 control units exchange information via serial communication. It also includes a three-phase AC voltage signal processing unit, used to process the signal after the three-phase AC input voltage passes through voltage divider resistors R1, R2, and R3 to obtain the current voltage value and phase sequence; a DC voltage signal processing unit, used to process the signal after the DC bus voltage passes through voltage divider resistor R3 to obtain the current DC bus voltage value; a DC current signal processing unit, used to process the signal after the DC bus current passes through voltage divider resistor R6 to obtain the current DC bus current value; a temperature signal processing unit, used to process the temperature signal to obtain the current temperature value; and a communication processing unit, used to use RS... The main control board communicates with the LCD screen via RS485 or RS232 communication. An indicator / relay output signal processing unit controls the on / off states of switches K1, K2, K3, K4, and K5. An input signal processing unit processes signals from start / stop switches SB1, SB2, and SB3 to determine the current running or stopped status. A resonant output voltage processing unit processes the resonant voltage signal after passing through voltage transformer VT1 to obtain the current resonant voltage value. A resonant output current processing unit processes the current signal after passing through current transformers CT1 or CT2 to obtain the current resonant current value. A PWM drive output control unit receives the PWM drive signal and outputs it to the drive board. A protection control unit processes and protects the system based on feedback signals from the drive board. A DC / DC power supply unit converts the 24V power supply to power the ARM1 and ARM2 control units.

[0013] The ARM1 control unit uses an STM32F4XX series chip; the ARM2 control unit uses an STM32F334 series chip.

[0014] The advantages of this utility model are:

[0015] 1. Structural design aspects

[0016] One-to-two structure, saving costs and space: The main circuit adopts a one-to-two structure, one main circuit can drive two control circuits. Compared with the traditional single-path control structure, it can effectively save costs, reduce the size of the equipment, and facilitate installation and layout. It is suitable for bolt heating application scenarios with limited space.

[0017] Independent control enhances flexibility and stability: The two control circuits operate independently. This design allows for flexible adjustment of the output power and frequency of each circuit during the heating process, based on actual needs, to meet the requirements of different bolt materials, sizes, and heating processes. It also improves system stability; if one circuit fails, the other can still operate normally, ensuring production continuity.

[0018] 2. Control accuracy and real-time performance

[0019] Dual ARM Chip Collaborative Control: The main control board employs dual ARM chips. ARM1 handles general signal processing such as AC voltage, temperature, and I / O signals, while ARM2 focuses on real-time and high-precision signal processing, including resonant output current and voltage acquisition and calculation, as well as PWM output. The two chips communicate via serial port, with clear division of labor and collaborative operation, effectively improving control accuracy and real-time performance. This ensures the stability and accuracy of the power output, meeting the precise temperature and power control requirements during bolt heating.

[0020] Multi-signal acquisition and processing: The control circuit acquires and processes multiple signals such as three-phase AC voltage, DC bus voltage, DC bus current, resonant output current, and resonant output voltage. It can monitor the power supply's operating status in real time, providing rich data support for precise control. This allows the power supply to adjust its output parameters in a timely manner according to actual operating conditions, ensuring consistent heating performance.

[0021] 3. Operation and monitoring aspects

[0022] Intelligent Human-Machine Interface: Equipped with a high-brightness medical-grade touch-screen LCD, it operates immediately upon power-up. It communicates with the main control board's ARM processor via RS232 or RS485, displaying real-time information such as output current, output power, output voltage, DC bus voltage, resonant frequency, three-phase AC input voltage, system version, system temperature, workpiece temperature, power information, and number of power-on cycles. Operators can easily set and modify parameters such as operating mode, target current, target power, and target temperature through the screen, achieving intelligent operation and monitoring, and improving production efficiency and product quality.

[0023] Real-time monitoring and feedback: The load is equipped with a spring-loaded temperature measuring device, which can provide real-time feedback on the workpiece temperature; at the same time, it has a water flow detection function, which can display the water flow value in real time, and automatically alarm and shut down when the water supply is interrupted, effectively protecting the equipment, preventing equipment damage caused by excessive temperature or insufficient cooling, extending the service life of the equipment, and reducing maintenance costs.

[0024] 4. Energy utilization and safety aspects

[0025] Intelligent fan start / stop: The relay output signal processing unit can control the start and stop of the fan. The fan runs when the equipment is running, and stops when the equipment stops if the system temperature is within the set range. This avoids the energy loss and noise pollution caused by the continuous operation of the fan in conventional induction heating power supplies, improves energy efficiency, and improves the working environment.

[0026] Multiple protection mechanisms: The control circuit has comprehensive protection functions, such as overcurrent, overvoltage, and overheat protection. When an abnormal situation is detected, it can quickly take protective measures, such as alarm shutdown, to ensure the safety of equipment and operators. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the main structure of this utility model.

[0028] Figure 2 This is a schematic diagram of the signal acquisition and control circuit of this utility model.

[0029] Figure 3 This is a block diagram of the main control system structure of this utility model.

[0030] Figure 4 This is a schematic diagram of the structure of the main control board U1 (main control board U2) of this utility model. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result of the description. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solution of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0032] See Figures 1 to 4This utility model relates to a medium-frequency induction heating power supply for bolt heating, including a main circuit and a control circuit; the main circuit is used to convert three-phase AC power into medium-frequency AC power and drive the induction heating load; the control circuit is used to realize intelligent control and protection of the power supply; the main circuit includes a rectifier bridge BD1, a buffer ceramic tube resistor R4, a reactor L0, an IGBT module, a shunt R6, a medium-frequency transformer TR1, a medium-frequency transformer TR2, a resonant capacitor bank C6, a resonant capacitor bank C10, and the induction heating load; the IGBT module includes... IGBT1, IGBT2, IGBT3, and IGBT4; external three-phase AC power is connected to rectifier bridge BD1 after passing through molded case circuit breaker QF. A high-frequency filter capacitor C1 is connected in parallel across rectifier bridge BD1. The positive terminal of the rectified DC voltage output is connected to one end of buffer ceramic tube resistor R4. The main contacts of the AC contactor are connected in parallel across R4. The other end of resistor R4 is connected to one end of reactor L0. The other end of reactor L0 is connected to the positive terminals of IGBT1, IGBT2, IGBT3, and IGBT4. The negative terminals of IGBT3 and IGBT4 return to the negative terminal of rectifier bridge BD1 via shunt R6. The output terminal of IGBT1 is connected to one end of the primary winding of intermediate frequency transformer TR1. The output terminal of IGBT2 is connected to the other end of the primary winding of transformer TR1 via DC blocking capacitor C5. The output terminal of IGBT3 is connected to one end of the primary winding of intermediate frequency transformer TR2. The output terminal of IGBT4 is connected to the other end of the primary winding of transformer TR2 via DC blocking capacitor C9. Absorption capacitors C3 and C4 are connected in parallel between IGBT1 and IGBT2. Absorption capacitors C7 and C8 are connected in parallel between IGBT3 and IGBT4. Filter capacitor bank C2 is connected in parallel between reactor L0 and the negative terminal of the IGBT module. One end of the secondary side of transformer TR1 is connected to resonant capacitor bank C6. The other end of resonant capacitor bank C6 is connected to an induction heating load. The other end of the induction heating load is connected back to the secondary side of transformer TR1. One end of the secondary side of transformer TR2 is connected to resonant capacitor bank C10. The other end of resonant capacitor bank C10 is connected to an induction heating load. The other end of the load is connected back to the secondary side of transformer TR2.

[0033] Among them, IGBT1, IGBT2, DC blocking capacitor C5, resonant capacitor group C6 and transformer TR1 are one circuit, while IGBT3, IGBT4, DC blocking capacitor C9, resonant capacitor group C10 and transformer TR2 are another circuit.

[0034] By designing the main circuit and control circuit, and combining the coordinated work of various components, the following advantages were achieved:

[0035] 1. Precise signal acquisition and monitoring

[0036] Three-phase AC voltage acquisition: By connecting sampling resistors R1, R2, and R3 to the main control boards U1 and U2, the three-phase AC voltage can be accurately acquired, ensuring the stability and reliability of the power input. This helps to monitor grid voltage fluctuations in real time, adjust control strategies promptly, and ensure the stability of the heating process.

[0037] DC bus voltage acquisition: Connected to main control boards U1 and U2 via sampling resistor R5, the DC bus voltage can be acquired in real time, ensuring its stability and providing a stable DC power supply to the IGBT modules. This helps improve power conversion efficiency and output stability.

[0038] Bus current acquisition: Connected to main control boards U1 and U2 via shunt R6, the bus current can be accurately acquired, and the power supply output current can be monitored in real time to ensure the stability and reliability of the power supply output. This helps prevent overcurrent and protects the safety of equipment and operators.

[0039] Resonant output current acquisition: Connected to main control boards U1 and U2 via current transformers CT1 and CT2, the resonant output current can be accurately acquired, allowing real-time monitoring of current changes in the heating load and ensuring the stability and uniformity of the heating process. This helps improve heating efficiency and heating quality.

[0040] Resonant output voltage acquisition: Connected to main control boards U1 and U2 via voltage transformers VT1 and VT2, the resonant output voltage can be accurately acquired, allowing real-time monitoring of voltage changes in the heating load and ensuring the stability and uniformity of the heating process. This helps improve heating efficiency and heating quality.

[0041] 2. Intelligent control and protection

[0042] Real-time monitoring and feedback: Through precise signal acquisition, the main control board can monitor the power supply's operating status in real time, promptly detect abnormalities, and take corresponding protective measures. This helps improve equipment reliability and safety, and reduces equipment failures and downtime.

[0043] Precise Control: By acquiring various signals in real time, the main control board can precisely control the power output and frequency of the power supply, ensuring the stability and uniformity of the heating process. This helps improve heating efficiency and quality, meeting the requirements of different bolt materials, sizes, and heating processes.

[0044] Multiple protection mechanisms: By monitoring various signals in real time, the main control board can implement multiple protection functions such as overcurrent, overvoltage, and overheating to ensure the safety of equipment and operators. This helps improve equipment reliability and safety, and reduce equipment failures and downtime.

[0045] 3. High-efficiency energy conversion and transmission

[0046] High-efficiency rectification and filtering: The rectifier bridge BD1 and high-frequency filter capacitor C1 efficiently convert three-phase AC power to DC power and filter out high-frequency harmonics, ensuring the stability of the DC bus voltage. This helps improve the power supply's conversion efficiency and output stability.

[0047] Stable Inversion and Transmission: The IGBT module and intermediate frequency transformers TR1 and TR2 efficiently invert DC power into intermediate frequency AC power and transmit it to the induction heating load. This helps improve energy transfer efficiency, reduce energy loss, and increase heating efficiency.

[0048] The function of the resonant capacitor bank: Resonant capacitor banks C6 and C10 can form a resonant circuit with intermediate frequency transformers TR1 and TR2, improving energy transfer efficiency and ensuring the stability and uniformity of the heating process. This helps to improve heating efficiency and heating quality.

[0049] 4. Flexible control and adjustment

[0050] Dual ARM Chip Collaborative Control: The main control boards U1 and U2 employ dual ARM chips for collaborative control, enabling precise signal processing and control. This helps improve control accuracy and real-time performance, ensuring the stability and reliability of the power output.

[0051] Flexible parameter adjustment: Operators can easily set and modify parameters such as operating mode, target current, target power, and target temperature via the LCD screen. This helps meet the requirements of different bolt materials, sizes, and heating processes, improving heating efficiency and quality. Independently controlled dual circuits: IGBT1, IGBT2, DC blocking capacitor C5, resonant capacitor bank C6, and transformer TR1 form one circuit; IGBT3, IGBT4, DC blocking capacitor C9, resonant capacitor bank C10, and transformer TR2 form the other circuit. Independent control of these two circuits enhances system flexibility and stability. This helps improve heating efficiency and quality, meeting the requirements of different bolt materials, sizes, and heating processes.

[0052] 5. Compact structural design

[0053] Space saving: The compact structural design allows for efficient integration of the main circuit and control circuitry, saving equipment size and space. This contributes to increased equipment integration, reduced footprint, and easier installation and layout.

[0054] Modular design: The modular design of the main circuit and control circuit makes equipment maintenance and upgrades more convenient. The connections between modules are clear, facilitating disassembly and replacement, reducing maintenance time and costs. This contributes to improved equipment reliability and maintainability.

[0055] 6. Environmental protection and energy conservation

[0056] Reduced energy loss: Through efficient energy conversion and transmission, the equipment can effectively reduce energy loss and improve energy utilization efficiency during operation. This helps to reduce energy consumption, reduce carbon emissions, and achieve environmental protection and energy conservation.

[0057] Reduced noise pollution: Through intelligent control, the equipment can reduce unnecessary operating time, lower noise pollution, and improve the working environment. This helps improve the comfort of the working environment and reduces the impact on operators.

[0058] With its advantages in precise signal acquisition and monitoring, intelligent control and protection, efficient energy conversion and transmission, flexible control and adjustment, compact structural design, and environmental protection and energy saving, it achieves efficient, stable and reliable bolt heating function, meeting the high requirements for bolt heating in modern industrial production.

[0059] In the main circuit, the three output terminals of the molded case circuit breaker QF are each connected to a sampling resistor, namely sampling resistor R1, sampling resistor R2, and sampling resistor R3. The output terminals of the molded case circuit breaker QF are connected to the main control board U1 and main control board U2 through sampling resistors R1, R2, and R3 to obtain the three-phase AC voltage. The rear end of the reactor L0 is connected to the main control board U1 and main control board U2 through sampling resistor R5 to obtain the DC bus voltage. The two ends of the shunt R6 are connected to the main control board U1 and main control board U2 to obtain the bus current. A current transformer CT1 is fitted onto the output connection line of IGBT1; a current transformer CT2 is fitted onto the output connection line of IGBT3. The output of current transformer CT1 is connected to the main control board U1, and the output of current transformer CT2 is connected to the main control board U2, used to obtain the resonant output current; the two ends of the resonant capacitor C6 are connected to the voltage transformer VT1; the two ends of the resonant capacitor C10 are connected to the voltage transformer VT2. The output of voltage transformer VT1 is connected to the main control board U1, and the output of voltage transformer VT2 is connected to the main control board U2, used to obtain the resonant output voltage. This structure, through the careful arrangement of various sampling resistors, shunts, current transformers, and voltage transformers in the main circuit and their connection to the main control board, achieves comprehensive monitoring and precise control of the power supply's operating status.

[0060] The three output terminals of the molded case circuit breaker QF are connected to the fan FAN via AC contactor KM3; one output terminal of the molded case circuit breaker QF and the input neutral wire are connected to the input terminal of the switching power supply P1, which outputs 24V+ and GND to power the control circuit.

[0061] The control circuit includes a signal acquisition and control circuit and a main control system. The signal acquisition and control circuit is connected to the main control system. The main control system includes a main control board, an LCD screen, and a driver board. The driver board amplifies the PWM signal sent from the main control board and drives the IGBT module to output the inverter. The LCD screen communicates with the ARM of the main control board via RS232 or RS485.

[0062] The signal acquisition and control circuit includes a power indicator HL1, a running indicator HL2, an alarm indicator HL3, a running indicator HL4, an alarm indicator HL5, a power indicator HL1, control switches K1, K2, K3, K4, and K5, a start / stop switch SB1, a start / stop switch SB2, and an emergency stop switch SB3. One end of the power indicator HL1 is connected to GND, and the other end is connected to 24V+. One end of the running indicator HL2 is connected to 24V+, and the other end is connected to GND via control switch K1. One end of the alarm indicator HL3 is connected to 24V+, and the other end is connected to GND via control switch K2. One end of indicator light HL4 is connected to 24V+, and the other end is connected to GND via control switch K3; one end of alarm indicator light HL5 is connected to 24V+, and the other end is connected to GND via control switch K3; control switches K1 and K2 are both controlled by the main control board U1; one end of the coil of fan relay K6 is connected to 24V+, and the other end is connected to GND via control switch K5; one end of start / stop switch SB1 is connected to 24V+, and the other end is connected to the main control board U1; one end of start / stop switch SB2 is connected to 24V+, and the other end is connected to the main control board U2; one end of emergency stop switch SB3 is connected to 24V+, and the other end is connected to both main control boards U1 and U2. When start / stop switch SB1 or start / stop switch SB2 is pressed, 24V+ is input to the main control board, and the equipment starts; when start / stop switch SB1 or start / stop switch SB2 is reset, 24V+ is disconnected from the main control board, and the equipment stops running. When the emergency stop switch SB3 is pressed, 24V+ is disconnected from the main control board, and the equipment stops urgently; when SB3 is reset, 24V+ is input to the main control board, and the equipment emergency stop signal is reset.

[0063] This signal acquisition and control circuit structure, through its carefully designed signal acquisition and control circuit and main control system, achieves intelligent control and protection of the medium-frequency induction heating power supply, bringing the following advantages:

[0064] 1. Intelligent control and protection

[0065] Precise Control: The main control system receives and collects various signals from the control circuit, enabling precise control of the power supply's start / stop, operating status, and protection functions. For example, operators can easily control the operation and shutdown of the equipment using start / stop switches SB1 and SB2; the emergency stop switch SB3 provides an emergency stop function, ensuring that the power supply can be quickly cut off in emergencies, protecting the safety of the equipment and operators.

[0066] Multiple protections: The control circuit has multiple protection functions, such as overcurrent, overvoltage, and overheat protection. When an abnormality is detected, the main control system can quickly take protective measures, such as illuminating alarm indicator lights HL3 and HL5, and disconnecting the fan relay K6, to ensure the safe operation of the equipment.

[0067] 2. Real-time monitoring and feedback

[0068] Operational Status Monitoring: Operators can monitor the equipment's operational status in real time via power indicator HL1, operation indicator HL2, operation indicator HL4, and alarm indicator HL3, alarm indicator HL5. Power indicator HL1 shows whether the power supply is on, operation indicator HL2 and HL4 show whether the equipment is operating normally, and alarm indicator HL3 and HL5 illuminate when a fault occurs, providing intuitive fault indication.

[0069] Fault Diagnosis: The main control system acquires various signals through the signal acquisition and control circuit, enabling real-time fault diagnosis of the equipment. For example, when overcurrent or overvoltage is detected, the main control system will illuminate the corresponding alarm indicator and take protective measures to help operators quickly locate and resolve the problem.

[0070] 3. Flexible operation and control

[0071] Start-stop control: Start-stop switches SB1 and SB2 provide flexible start-stop control functions. Operators can easily control the operation and stop of the equipment by pressing or resetting these switches, improving the convenience and flexibility of operation.

[0072] Emergency Stop: The emergency stop switch SB3 provides an emergency stop function. In an emergency, the operator can quickly press the emergency stop switch to cut off the power supply and ensure the safety of the equipment and the operator.

[0073] 4. Highly efficient energy conversion and transmission

[0074] PWM signal amplification and driving: The driver board amplifies the PWM signal sent from the main control board and drives the IGBT module to invert and output the signal. This design ensures accurate amplification and transmission of the PWM signal, improving energy conversion efficiency and output stability.

[0075] Real-time adjustment: The main control system can adjust the frequency and amplitude of the PWM signal in real time by acquiring various signals through the signal acquisition and control circuit, so as to ensure that the output of the IGBT module meets the heating requirements, thereby improving heating efficiency and heating quality.

[0076] 5. User-friendly interface

[0077] LCD screen display: The LCD screen communicates with the ARM processor of the main control board via RS232 or RS485 to display the device's operating status and parameters in real time. Operators can easily set and modify parameters such as operating mode, target current, target power, and target temperature through the screen, improving the convenience and flexibility of operation.

[0078] Intuitive indicator lights: Various indicator lights provide intuitive operating status and fault indication, helping operators quickly understand the equipment's operating status and improving the convenience and safety of operation.

[0079] 6. Easy to maintain and upgrade

[0080] Modular design: The control circuit adopts a modular design, with clear connections between components, facilitating disassembly and replacement. This helps improve the maintainability and upgradeability of the equipment, reducing maintenance time and costs.

[0081] Fault Diagnosis and Early Warning: The main control system acquires various signals through the signal acquisition control circuit, providing detailed fault diagnosis information to help maintenance personnel quickly locate and resolve problems. Simultaneously, the system also features a fault early warning function, enabling appropriate protective measures to be taken before a fault occurs, reducing equipment maintenance costs and downtime.

[0082] This signal acquisition and control circuit structure achieves efficient, stable, and reliable bolt heating functions through its advantages in intelligent control and protection, real-time monitoring and feedback, flexible operation and control, efficient energy conversion and transmission, user-friendly interface, and ease of maintenance and upgrades, thus meeting the high requirements for bolt heating in modern industrial production.

[0083] The main control boards U1 and U2 have the same structure, both including an ARM1 control unit and an ARM2 control unit. The ARM1 control unit is used for processing AC voltage, temperature, and I / O signals; the ARM2 unit is used for acquiring and calculating resonant output current and voltage, as well as processing PWM output. The ARM1 and ARM2 control units exchange information via serial communication. It also includes a three-phase AC voltage signal processing unit, used to process the signal after the three-phase AC input voltage passes through voltage divider resistors R1, R2, and R3 to obtain the current voltage value and phase sequence; a DC voltage signal processing unit, used to process the signal after the DC bus voltage passes through voltage divider resistor R3 to obtain the current DC bus voltage value; a DC current signal processing unit, used to process the signal after the DC bus current passes through voltage divider resistor R6 to obtain the current DC bus current value; a temperature signal processing unit, used to process the temperature signal to obtain the current temperature value; and a communication processing unit, used to use RS... The main control board communicates with the LCD screen via RS485 or RS232 communication. An indicator / relay output signal processing unit controls the on / off states of switches K1, K2, K3, K4, and K5. An input signal processing unit processes signals from start / stop switches SB1, SB2, and SB3 to determine the current running or stopped status. A resonant output voltage processing unit processes the resonant voltage signal after passing through voltage transformer VT1 to obtain the current resonant voltage value. A resonant output current processing unit processes the current signal after passing through current transformers CT1 or CT2 to obtain the current resonant current value. A PWM drive output control unit receives the PWM drive signal and outputs it to the drive board. A protection control unit processes and protects the system based on feedback signals from the drive board. A DC / DC power supply unit converts the 24V power supply to power the ARM1 and ARM2 control units.

[0084] The ARM1 control unit uses an STM32F4XX series chip; the ARM2 control unit uses an STM32F334 series chip.

[0085] This main control board structure, through the coordinated operation of dual ARM control units and multiple functional units, achieves efficient and precise control and protection of the medium-frequency induction heating power supply, bringing the following advantages:

[0086] 1. Highly efficient and precise control and processing

[0087] Dual ARM cooperating: Both main control boards U1 and U2 contain an ARM1 control unit and an ARM2 control unit. The ARM1 control unit is responsible for processing AC voltage, temperature, and I / O signals, while the ARM2 control unit is responsible for acquiring and calculating resonant output current and voltage, as well as processing PWM output. This clearly defined dual ARM architecture can efficiently handle various signals and control tasks, improving the system's control accuracy and real-time performance.

[0088] Serial communication exchange: The ARM1 control unit and the ARM2 control unit exchange information through serial communication, which ensures the stability and reliability of data transmission, enabling the two control units to work together to realize complex control logic and functions.

[0089] 2. Comprehensive signal processing and monitoring

[0090] Three-phase AC voltage signal processing: The three-phase AC voltage signal processing unit can process the signal after passing through voltage divider resistors R1, R2, and R3 to obtain the current voltage value and phase sequence. This helps to monitor the grid voltage in real time and ensure the stability and reliability of the power input.

[0091] DC voltage signal processing: The DC voltage signal processing unit can process the signal after passing through the voltage divider resistor R3 to obtain the current DC bus voltage value. This helps to monitor the DC bus voltage in real time and ensure the stable operation of the IGBT module.

[0092] DC current signal processing: The DC current signal processing unit can process the signal after passing through the voltage divider resistor R6 to obtain the current DC bus current value. This helps to monitor the DC bus current in real time, prevent overcurrent, and protect the safety of equipment and operators.

[0093] Temperature signal processing: The temperature signal processing unit can process temperature signals to obtain the current temperature value. This helps to monitor the equipment temperature in real time, prevent overheating, and ensure the safe operation of the equipment.

[0094] Resonant output voltage and current processing: The resonant output voltage processing unit and the resonant output current processing unit process the signals after passing through voltage transformer VT1 and current transformer CT1 or CT2, respectively, to obtain the current resonant voltage and current values. This helps to monitor the voltage and current of the heating load in real time, ensuring the stability and uniformity of the heating process.

[0095] 3. Flexible control and operation

[0096] Indicator / Relay Output Signal Processing: The indicator / relay output signal processing unit can control the on / off states of control switches K1, K2, K3, K4, and K5 to indicate and control the equipment's operating status. For example, the running indicator and alarm indicator can visually display the equipment's operating status and fault conditions.

[0097] Switch input signal processing: The switch input signal processing unit can process the signals from start / stop switch SB1, start / stop switch SB2, and emergency stop switch SB3 to determine the current running and stopping status. This allows operators to easily control the start / stop and emergency stop of the equipment, improving operational flexibility and safety.

[0098] 4. Stable communication and display

[0099] Communication Processing Unit: The communication processing unit uses RS232 or RS485 communication methods to achieve stable communication between the main control board and the LCD screen. This allows operators to monitor the equipment's operating status and parameters in real time through the LCD screen, improving the convenience and flexibility of operation.

[0100] LCD screen display: The LCD screen can display the equipment's operating status and parameters in real time, such as output current, output power, output voltage, DC bus voltage, resonant frequency, three-phase AC input voltage, system version, system temperature, workpiece temperature, power information, and number of power-on cycles. This helps operators understand the equipment's operating status in a timely manner and make corresponding adjustments and controls.

[0101] 5. Reliable protection and security

[0102] Protection and Control Unit: The protection and control unit processes and protects against feedback signals from the drive board, providing multiple protection functions such as overcurrent, overvoltage, and overheating. When an abnormality is detected, it can quickly take protective measures, such as illuminating alarm indicator lights and disconnecting fan relays, to ensure the safety of equipment and operators.

[0103] Emergency stop function: The SB3 emergency stop switch provides an emergency stop function, which can quickly cut off the power supply in an emergency to ensure the safety of equipment and operators.

[0104] 6. Highly efficient energy conversion and transmission

[0105] PWM Drive Output Control Unit: The PWM drive output control unit generates PWM drive signals and outputs them to the driver board to control the inverter output of the IGBT module. This helps improve energy conversion efficiency and output stability, ensuring efficient heating.

[0106] This main control board structure achieves efficient, stable, and reliable control of the medium-frequency induction heating power supply through its advantages in efficient and precise control and processing, comprehensive signal processing and monitoring, flexible control and operation, stable communication and display, reliable protection and safety, efficient energy conversion and transmission, and ease of maintenance and upgrading. It meets the high requirements for bolt heating in modern industrial production.

[0107] This utility model relates to a medium-frequency induction heating power supply for bolt heating, the working principle of which mainly involves the coordinated operation of the main circuit and the control circuit. The working principle of this utility model will be explained in detail below with reference to the mentioned components and sequential steps:

[0108] 1. Working principle of the main circuit

[0109] 1.1 Input and Rectification of Three-Phase Alternating Current

[0110] Molded case circuit breaker QF: External three-phase AC power first passes through the molded case circuit breaker QF to protect the circuit from overload and short circuit.

[0111] Rectifier bridge BD1: Three-phase AC power passes through the molded case circuit breaker QF and is connected to rectifier bridge BD1. Rectifier bridge BD1 rectifies the three-phase AC power into DC power.

[0112] High-frequency filter capacitor C1: A high-frequency filter capacitor C1 is connected in parallel across the rectifier bridge BD1 to filter out high-frequency harmonics and ensure the stability of the DC bus voltage.

[0113] 1.2 Stabilization and buffering of DC bus voltage

[0114] Buffer ceramic tube resistor R4: The positive terminal of the rectified DC voltage output is connected to one end of the buffer ceramic tube resistor R4 to limit surge current and protect subsequent circuits.

[0115] Reactor L0: The other end of the buffer ceramic tube resistor R4 is connected to one end of reactor L0. Reactor L0 is used to smooth DC current and reduce current fluctuations.

[0116] Shunt R6: The other end of reactor L0 is connected to the positive terminal of IGBT module, and the negative terminal of IGBT module returns to the negative terminal of rectifier bridge BD1 through shunt R6.

[0117] Shunt R6 is used for accurate measurement of bus current.

[0118] 1.3 Inverter Output of IGBT Module

[0119] IGBT Modules: The IGBT modules include IGBT1, IGBT2, IGBT3, and IGBT4. These IGBT modules invert DC power into intermediate frequency AC power. DC Blocking Capacitors C5 and C9: The output of IGBT1 is connected to one end of the primary winding of the intermediate frequency transformer TR1, and the output of IGBT2 is connected to the other end of the primary winding of transformer TR1 via DC blocking capacitor C5. Similarly, the output of IGBT3 is connected to one end of the primary winding of the intermediate frequency transformer TR2, and the output of IGBT4 is connected to the other end of the primary winding of transformer TR2 via DC blocking capacitor C9. The DC blocking capacitors prevent DC components from entering the transformer. Absorption Capacitors C3, C4, C7, and C8: Absorption capacitors C3 and C4 are connected in parallel between IGBT1 and IGBT2, and absorption capacitors C7 and C8 are connected in parallel between IGBT3 and IGBT4. These capacitors absorb voltage spikes generated during IGBT switching, protecting the IGBT modules.

[0120] 1.4 Intermediate Frequency Transformer and Resonant Capacitor Bank

[0121] Intermediate frequency transformers TR1 and TR2: Intermediate frequency transformers TR1 and TR2 step up or step down the inverted intermediate frequency AC power to meet the needs of the induction heating load. Resonant capacitor banks C6 and C10: One end of the secondary side of transformer TR1 is connected to resonant capacitor bank C6, and the other end of resonant capacitor bank C6 is connected to the induction heating load. Similarly, one end of the secondary side of transformer TR2 is connected to resonant capacitor bank C10, and the other end of resonant capacitor bank C10 is connected to the induction heating load. The resonant capacitor banks and transformers form a resonant circuit, improving energy transfer efficiency.

[0122] 2. Working principle of the control circuit

[0123] 2.1 Signal Acquisition and Monitoring

[0124] Three-phase AC voltage acquisition: Sampling resistors R1, R2, and R3 are connected to main control boards U1 and U2 to acquire three-phase AC voltage signals, ensuring the stability and reliability of the power input. DC bus voltage acquisition: Sampling resistor R5 is connected to main control boards U1 and U2 to acquire DC bus voltage signals, ensuring the stability of the DC bus voltage. Bus current acquisition: Shunt resistor R6 is connected to main control boards U1 and U2 to acquire bus current signals, ensuring the stability and reliability of the power output. Resonant output current acquisition: Current transformers CT1 and CT2 are connected to main control boards U1 and U2 to acquire resonant output current signals, ensuring the stability and uniformity of the heating process. Resonant output voltage acquisition: Voltage transformers VT1 and VT2 are connected to main control boards U1 and U2 to acquire resonant output voltage signals, ensuring the stability and uniformity of the heating process.

[0125] 2.2 Intelligent Control and Protection

[0126] Main Control Boards U1 and U2: Main control boards U1 and U2 employ dual ARM chips for collaborative control. ARM1 control unit is responsible for processing AC voltage, temperature, and I / O signals, while ARM2 control unit is responsible for acquiring and calculating resonant output current and voltage, as well as processing PWM output. The two control units communicate with each other via serial port. Signal Processing Unit: The main control board includes multiple signal processing units, such as a three-phase AC voltage signal processing unit, a DC voltage signal processing unit, a DC current signal processing unit, a temperature signal processing unit, a resonant output voltage processing unit, and a resonant output current processing unit, used to process various signals and ensure stable system operation. Protection Control Unit: Based on feedback signals from the driver board, this unit processes and protects against overcurrent, overvoltage, and overheating, ensuring the safety of equipment and operators.

[0127] 2.3 Generation and Driving of PWM Signals

[0128] PWM drive output control unit: The main control board generates a PWM drive signal, which is then amplified by the drive board to drive the IGBT module to output the inverter, ensuring the high efficiency and stability of energy conversion.

[0129] 2.4 Operation and Monitoring Interface

[0130] LCD Screen: Communicates with the main control board's ARM processor via RS232 or RS485 to display real-time equipment operating status and parameters, such as output current, output power, output voltage, DC bus voltage, resonant frequency, three-phase AC input voltage, system version, system temperature, workpiece temperature, power information, and number of power-on cycles. Operators can set and modify parameters such as operating mode, target current, target power, and target temperature through the screen. Indicator Lights and Switches: Power indicator HL1, operation indicator HL2, alarm indicator HL3, operation indicator HL4, alarm indicator HL5, and control switches K1, K2, K3, K4, and K5 provide intuitive operating status and fault indications, helping operators quickly understand the equipment's operating condition. Start / Stop Switches SB1 and SB2: Operators can conveniently control the operation and stop of the equipment by pressing or resetting these switches. Emergency Stop Switch SB3: Provides an emergency stop function, ensuring rapid power cut-off in emergencies to protect the equipment and operator safety.

[0131] 3. Work Process

[0132] 1. Power input: External three-phase AC power passes through the molded case circuit breaker QF and is connected to the rectifier bridge BD1, where it is rectified into DC power.

[0133] 2. Stable DC bus voltage: The DC current passes through the buffer ceramic tube resistor R4 and the reactor L0 to ensure the stability of the DC bus voltage.

[0134] 3. Inverter Output: The IGBT module inverts DC power into medium-frequency AC power, which is transmitted to resonant capacitor banks C6 and C10 through medium-frequency transformers TR1 and TR2 to form a resonant circuit that drives the induction heating load.

[0135] 4. Signal Acquisition and Monitoring: The main control board U1 and main control board U2 acquire signals through various sampling resistors, shunts, current transformers and voltage transformers to monitor the power supply's operating status in real time.

[0136] 5. Intelligent control: The main control board precisely controls the output power and frequency of the power supply based on the collected signals to ensure the stability and uniformity of the heating process.

[0137] 6. Protection functions: The main control board has multiple protection functions such as overcurrent, overvoltage, and overheat protection to ensure the safety of equipment and operators.

[0138] 7. Operation and monitoring interface: Operators can easily control the operation of the equipment and monitor its status through the LCD screen and various indicator lights and switches.

[0139] Through the coordinated operation of the main circuit and control circuit described above, this utility model achieves a highly efficient, stable, and reliable bolt heating function, meeting the high requirements for bolt heating in modern industrial production.

[0140] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A medium-frequency induction heating power supply for heating bolts, characterized in that, It includes a main circuit and a control circuit; the main circuit is used to convert three-phase AC power into medium-frequency AC power and drive an induction heating load; the control circuit is used to realize intelligent control and protection of the power supply; the main circuit includes a rectifier bridge BD1, a buffer ceramic tube resistor R4, a reactor L0, an IGBT module, a shunt R6, a medium-frequency transformer TR1, a medium-frequency transformer TR2, a resonant capacitor bank C6, a resonant capacitor bank C10, and an induction heating load; the IGBT module includes IGBT1, IGBT2, IGBT3, and IGBT4; External three-phase AC power is connected to rectifier bridge BD1 after passing through molded case circuit breaker QF. A high-frequency filter capacitor C1 is connected in parallel across rectifier bridge BD1. The positive terminal of the rectified DC output voltage is connected to one end of buffer ceramic tube resistor R4. The main contacts of the AC contactor are connected in parallel across R4. The other end of resistor R4 is connected to one end of reactor L0. The other end of reactor L0 is connected to the positive terminals of IGBT1, IGBT2, IGBT3, and IGBT4. The negative terminals of IGBT1, IGBT2, IGBT3, and IGBT4 return to the negative terminal of rectifier bridge BD1 via shunt R6. The output terminal of IGBT1 is connected to one end of the primary winding of intermediate frequency transformer TR1. The output terminal of IGBT2 is connected to the other end of the primary winding of transformer TR1 via DC blocking capacitor C5. The output terminal of IGBT3... The output terminal is connected to one end of the primary side of the intermediate frequency transformer TR2. The output terminal of the IGBT4 is connected to the other end of the primary side of the transformer TR2 through the DC blocking capacitor C9. The absorption capacitors C3 and C4 are connected in parallel between the IGBT1 and IGBT2. The absorption capacitors C7 and C8 are connected in parallel between the IGBT3 and IGBT4. The filter capacitor group C2 is connected in parallel between the reactor L0 and the negative terminal of the IGBT module. One end of the secondary side of the transformer TR1 is connected to the resonant capacitor group C6. The other end of the resonant capacitor group C6 is connected to the induction heating load. The other end of the induction heating load is connected back to the secondary side of the transformer TR1. One end of the secondary side of the transformer TR2 is connected to the resonant capacitor group C10. The other end of the resonant capacitor group C10 is connected to the induction heating load. The other end of the load is connected back to the secondary side of the transformer TR2.

2. The medium-frequency induction heating power supply for bolt heating according to claim 1, characterized in that, In the main circuit, the three output terminals of the molded case circuit breaker QF are each connected to a sampling resistor, namely sampling resistor R1, sampling resistor R2, and sampling resistor R3. The output terminals of the molded case circuit breaker QF are connected to the main control board U1 and main control board U2 through sampling resistors R1, R2, and R3 to obtain the three-phase AC voltage. The rear end of the reactor L0 is connected to the main control board U1 and main control board U2 through sampling resistor R5 to obtain the DC bus voltage. The two ends of the shunt R6 are connected to the main control board U1 and main control board U2 to obtain the bus current. A current transformer CT1 is fitted onto the output connection line of IGBT1; a current transformer CT2 is fitted onto the output connection line of IGBT3. The output of current transformer CT1 is connected to the main control board U1, and the output of current transformer CT2 is connected to the main control board U2, for obtaining the resonant output current; the two ends of resonant capacitor C6 are connected to voltage transformer VT1; the two ends of resonant capacitor C10 are connected to voltage transformer VT2. The output of voltage transformer VT1 is connected to the main control board U1, and the output of voltage transformer VT2 is connected to the main control board U2, for obtaining the resonant output voltage.

3. The medium-frequency induction heating power supply for bolt heating according to claim 1 or 2, characterized in that, The three output terminals of the molded case circuit breaker QF are connected to the fan FAN via AC contactor KM3; one output terminal of the molded case circuit breaker QF and the input neutral wire are connected to the input terminal of the switching power supply P1, which outputs 24V+ and GND to power the control circuit.

4. The medium-frequency induction heating power supply for bolt heating according to claim 3, characterized in that, The control circuit includes a signal acquisition and control circuit and a main control system. The signal acquisition and control circuit is connected to the main control system. The main control system includes a main control board, an LCD screen, and a driver board. The driver board amplifies the PWM signal sent from the main control board and drives the IGBT module to output the inverter. The LCD screen communicates with the ARM of the main control board via RS232 or RS485.

5. The medium-frequency induction heating power supply for bolt heating according to claim 4, characterized in that, The signal acquisition and control circuit includes a power indicator HL1, a running indicator HL2, an alarm indicator HL3, a running indicator HL4, an alarm indicator HL5, a power indicator HL1, control switches K1, K2, K3, K4, and K5, a start / stop switch SB1, and a start / stop switch SB2. One end of the power indicator HL1 is connected to GND, and the other end is connected to 24V+. One end of the running indicator HL2 is connected to 24V+, and the other end is connected to GND via control switch K1. One end of the alarm indicator HL3 is connected to 24V+, and the other end is connected to 24V+ via control switch K2. The running indicator HL1... One end of L4 is connected to 24V+, and the other end is connected to GND via control switch K3; one end of alarm indicator HL5 is connected to 24V+, and the other end is connected to GND via control switch K3; control switches K1 and K2 are both controlled by the main control board U1; one end of the coil of fan relay K6 is connected to 24V+, and the other end is connected to GND via control switch K5; one end of start / stop switch SB1 is connected to 24V+, and the other end is connected to the main control board U1; one end of start / stop switch SB2 is connected to 24V+, and the other end is connected to the main control board U2; one end of emergency stop switch SB3 is connected to 24V+, and the other end is connected to both the main control board U1 and the main control board U2.

6. The medium-frequency induction heating power supply for bolt heating according to claim 5, characterized in that, The main control boards U1 and U2 have the same structure, both including an ARM1 control unit and an ARM2 control unit. The ARM1 control unit is used for processing AC voltage, temperature, and IO signals; the ARM2 unit is used for acquiring and calculating resonant output current and voltage, as well as processing PWM output; the ARM1 control unit and the ARM2 control unit exchange information through serial communication; it also includes a three-phase AC voltage signal processing unit, used to process the signal after the three-phase AC input voltage passes through voltage divider resistors R1, R2, and R3, to obtain the current voltage value and voltage phase sequence; The DC voltage signal processing unit is used to process the signal of the DC bus voltage after passing through the voltage divider resistor R3 to obtain the current DC bus voltage value. The DC current signal processing unit is used to process the signal of the DC bus current after passing through the voltage divider resistor R6 to obtain the current DC bus current value. The temperature signal processing unit is used to process the temperature signal and obtain the current temperature value. The communication processing unit is used to process communication between the main control board and the LCD screen using RS232 or RS485 communication methods. The indicator / relay output signal processing unit is used to control the on / off state of switches K1, K2, K3, K4 and K5. The switch input signal processing unit is used to process the signals of emergency stop switch SB1, emergency stop switch SB2, and emergency stop switch SB3, and to determine the current running and stopping status. The resonant output voltage processing unit is used to process the signal after the resonant voltage passes through the voltage transformer VT1 to obtain the current resonant voltage value. The resonant output current processing unit is used to process the signal after the current passes through the current transformer CT1 or CT2 to obtain the current resonant current value. The PWM drive output control unit is used to obtain the PWM drive signal and output it to the driver board; The protection control unit is used to process and protect based on the feedback signals from the driver board; The DC / DC power supply unit is used to convert the 24V power supply to power the ARM1 control unit and the ARM2 control unit.

7. The medium-frequency induction heating power supply for bolt heating according to claim 6, characterized in that, The ARM1 control unit uses an STM32F4XX series chip; the ARM2 control unit uses an STM32F334 series chip.

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