DSP-Based Resistance Spot Welding Signal Acquisition And FFT Analysis System

Real-time sampling the signals of welding current and voltage between two electrodes, displaying waveforms on LCD, spectrum analysis are important research approaches of resistance spot welding (RSW) quality control in the process of RSW.Using resistance spot welding current and voltage between two electrodes as signal source, a DSP-based signal acquisition and analysis system is developed. Signal sampling, FFT, LCD displaying of waveform and spectrum, and PC archiving were realized by the system. The main chip of the system hardware is TMS320F240 digital signal processor, and the LCD is driven by SED1335F chip. Employing Linear Optocoupler LOC110 in signal regulating circuit, signal earth is effectively separated from digital earth. System software is made with C and Assembler. For the core subroutine is made with Assembler, the system software execute more speedily. The communication interface between DSP system and PC is made with C++ Builder, through which data can be transmitted to PC. Several Electro Magnetic Compatibility measures were undertaken such as Linear Optocoupler separating, mixed earthing etc. So designed DSP system worked steadily in high-current and intense magnetic field environment.Experimental results show that the system can be used to sample signal, analyze and display waveform on welding field.This research is of important engineering value to real-time test of resistance spot and seam welding quality.