80KVA PLC Controlled Three-Phase Medium Frequency DC Spot Welding Machine
Medium frequency inverter DC resistance control system: Refer to the following picture, the three-phase AC current has been rectified into DC. Then convert into medium frequency 1000Hz square wave and connected into primary of welding transformer through inverter circuit which is composed of IGBT. After the rectification through welding transformer, the current become DC with small pulsation and being supplied to electrode for welding. The inverter will adjust the duty cycle rate of IGBT according to the feedback of primary and secondary welding current so as to achieve constant current during welding process.