Preheat Welding with Induction Heating Based Control of Phase-Locked Loop Resonant Inverter

This paper proposes application of induction heating for surface heating. Use electric welding with control duty cycle of buck converter and frequency inverter by Phase Lock Loop (PLL), adjust the resonance frequency at switch inverter circuit high frequency pulse generator and constant phase angle control unit IC dsPIC33F. Switching Frequency of Buck Converter 20kHz. The switch inverter can operation under zero-voltage-switch inverter (ZVS). A prototype power output a 1.5 kW, can heat a steel plate 300 mm long, 500 mm wide, and 4.5 mm thick at temperature 287°.