A Study On Microcontroller System And Its Reliability Design In Spot Welding

This topic carries on the constant current control to the resistance spot welding process using a system of single chip computer, whose core has used the C8051F005. In the main circuit, the inverse parallel couple SCRs(silicon-controlled rectifier) are used as a electric switch, switching the transformer of resistance spot welding. The control system produces feedback regulation by use of such electric units as detecting driving circuits, orders pressure to work piece with solenoid valve and pneumatic mechanism. Each process time parameter as well as the power parameter of resistance spot welding may be preset and input into the memory of the microcontroller.This control method of this topic is variable coefficient PID control based on the modern control theory and traditional theory, transforming the non-linearity process in welding into the linear relations with help of subsection. The design of software implements modulation, of which the important modules were the welding control module and the PID control module. The main function of welding control module is current sampling, digital filtering, computing current effective value, while PID control module mainly processes AD conversion value and computes the variable quantity of pilot angle of SCRs and re-adjusts the angle.The study is put forward on improving the reliability of control system, in which the actual noise source and the disturbance way are considered, so some measures are taken for the overall system reliability such as hardware design to guard against disturbance, the printed circuit board designed against noise and the anti-interference software.A desired result can be achieved by debugging the software and hardware and the actual welding experiments.