Design and Implementation of Full-Bridge Resonant Inverter with PLL Control for Induction Welding Applications

This paper presents the design and implementation of a Full-Bridge Resonant (FBR) inverter employing Zero-Voltage Switching (ZVS) for induction welding applications. The proposed system aims to improve efficiency, reduce switching losses, and achieve a compact and lightweight welding power supply. The inverter is designed to operate at a high switching frequency of 35 kHz with an input voltage of 400 VDC and a maximum output current of 120 A, delivering a rated output power of 9.6 kW. A Phase-Locked Loop (PLL) control system implemented on a TMS320F28335 DSP is used to synchronize the inverter’s switching frequency with the resonant current, ensuring stable ZVS operation under varying load conditions. Simulation and experimental results verify that the inverter achieves smooth and stable arc welding performance. The measured output voltage and current are approximately 60–80 V and 110–120 A, respectively, producing a uniform weld bead with minimal spatter and excellent penetration. The experimental prototype demonstrates that the proposed FBR inverter provides high efficiency, stable operation, and reduced thermal stress on power switches. With its compact design and high power density, the inverter is suitable for modern welding systems. It can also be applied to other high-frequency industrial processes such as induction heating and metal melting applications.