Research On The Control System Of Inverter-based Resistance Spot Welder With Microcomputer

The complexity of welding course, melt nuclear uncertainty of forming process, especially some weld course's quality control adopt simple method determine the quality control of spot welding is an very arduous task. The premise of resistance spot welding process and its quality is to real-time sampling and processing of the concerned date or parameters during the spot welding, the correction of signal sampling is the key factor of whole control system. So the research on the real-time signal sampling and processing technology is very instructive and important to the quality controlling of spot welding.In this paper, aiming at the low precision; poor real-time and complicated circuit of the traditional spot welding controller and parameters testing system, a date sampling and processing method which can be used to sampling and processing the value of welding current, the value of voltage between electrodes and welding time with high speed and high precision is introduced through software calculating and reasonable simple but reliable hardware circuit.The principle of the main circuit, choice of the control parameters, choice of the control algorithm and the principle of point-by-point integration method are first introduced in this paper. Secondly, gave an explanation about controller's design principle which used welding current and voltage between the electrodes for input and output a voltage to control the phase shifting of the PWM. Based on the requirement of high performance about the microprocessor of multi-parameters control system, we chose 80C196KC SCM for the core, and the hardware circuit which consisted of input circuit, output circuit, sampling enabling signal circuit and alarming are analyzed. The ideology of software developing, the main program, the interrupt service program, the sampling program, and other function program and the system's anti-interference measure are introduced systematically. At last, debug the keyboard, LED display, I/O port and the A/D port of current and voltage, and the soft ware of PID program.The control system we have designed has simple structure, operating fast, can meet the need of the inverter-based resistance spot welder, and has such functions as parameter setting up , parameter showing , fault alarms etc, capable of the multi parameters and informationsampling and processing of the spot welding process, has some theory and practical value of the realization of the inverter-based resistance spot welder's process and quality intelligent control.