Wei Lianghong, Zeng Min, Luo Jingrong and Chen Guanghui (South China University of Technology, Guangzhou 510641, Guangdong)

ABSTRACT: The improvement of welding quality of medium frequency inverted resistance welding depends on the improvement of detection technology. Traditional detection methods have the disadvantages of too large volume and low detection accuracy. In order to improve the control accuracy and response speed of IF inverted resistance welding equipment, an electric parameter detection system based on constant current control method is designed. The system includes primary current detection module, primary voltage detection module and secondary voltage detection module. True RMS processing circuit and secondary voltage detection circuit are introduced in detail. The disposal of primary current and secondary voltage by sampling circuit is tested by experiment, and the waveform of sampling and disposal is analyzed and verified. The results show that the primary current detection circuit and the secondary voltage detection circuit can accurately measure the effective value of the primary current and the voltage between the electrodes. The welding product has excellent performance and meets the higher welding process requirements.

Key words: Constant current control; Primary current; Secondary voltage; True RMS