Design, Simulation and Hardware Implementation of Soft Switching based Induction Heating System

Induction heaters are being used widely for heating magnetic materials in various industrial and research applications particularly for controlled precision heating requirements. Induction heating has advantages like noncontact type heating, high efficiency, surface hardening, clean heating, etc. compared to other methods of heating. The power circuit configuration used for induction heating system in several applications is inverter circuit based on hard switching which increases losses in the inverter bridge particularly for high current, high frequency switching applications. The soft switching type induction heaters have advantages of lower switching power loss and high frequency operation and hence can be used for heating in various process applications. In this paper, different soft switching methods like load resonance soft switching, zero voltage switching, zero current switching have been described. Analyzing the results of various soft switching methods, parallel load resonance method has an advantage if operated near resonance where all reactive current required by induction coil need not be supplied by source. Considering parallel load resonance method, soft switching is achieved at both turn ON and turn OFF incidences of solid state switches used in inverter circuit. The paper presents design, modeling, simulation and hardware implementation of soft switching technique based induction heater focusing reduced switching losses in the switching devices.