Research On Medium Frequency Inverter Welding Power Supply System Based On The Touch Screen Controlling

Resistance welding inverter technology plays an important role in industrial production. In recent years, with the development of the new technology of power electronics and modern control theory, as well as the emergence of new competing materials, inverter welding power is gradually toward digital, multi-functional and high-precision direction. In domestic, there exist cumbersome welding parameter settings, low control accuracy and low intelligence in inverter welding power, and also the equalizing resistance of the main circuit exists large heating and short life. According to these problems, this paper proposes an "intermediate frequency inverter welding power system based on the touch screen controlling." In the system, the industrial touch screen, which is used as the upper computer, can group control multiple medium frequency inverter welding powers used as the slave machine. In the design of medium frequency inverter welding power, it adopts DSP and MCU to design the digital control circuit, also it gives full play to the advantages of powerful data processing capability on DSP and powerful control capability on MCU.In the main circuit of medium frequency inverter welding power, it firstly introduces the mechanism of IGBT spike voltage pulse generated and explores measures to reduce the voltage spike, including using laminated busbar structure and adding the buffer circuit in the main circuit. Then, a model of the inverter circuit has been built in the MATLAB environment and experimental simulation has been done, In the control circuit, it mainly introduces the control system hardware circuit composed by DSP and MCU. Firstly it designs a multi-output flyback regulator switching power supply, and then it designs A/D sampling circuit, over-voltage protection circuit, a capacitor terminal voltage detection control circuit, phase protection circuit, three-phase half-controlled rectifier bridge trigger circuit, IGBT drive circuit and so on. In the software control strategies of the welding power source, it uses modular programming ideas, focusing on the design of the A/D sampling subroutine, PWM control subroutine and constant current control algorithm. Finally, it gives writing process of the touch screen software interface based on the development of the touch screen which is used as a upper machine.Through experimental test, it can solve some technical problems when using medium frequency inverter welding power system based on the touch screen controlling. After adopting the laminated busbar structure in the main circuit and adding the discharge-suppressing RCD buffer circuit, it effectively reduces the peak voltage across the IGBT. After applying the capacitor control terminal voltage detection circuit, it not only avoids equalizing resistors been in a state of current consumption but also saves energy and enhances the thermal stability of the power system. In the constant current control algorithm, it innovatively applies the digital integral separation PID control algorithm with dead zone. As a result, it significantly improves the welding process real-time control. As the host computer, the touch screen can group control multiple equipments of welding power source, and it completely solves the tedious process of welding power source parameter settings.