Investigation on Resonant Converters for Induction Heating Applications

Abstract

In this research work, the investigations on various converter topologies to feed newlinepower to single, two and three coil fed induction heating (IH) systems has been developed. newlineThe mathematical analysis, circuit simulation, finite element study and experimental newlineinvestigation for heating/cooking application are performed for 1 kW power newlinerating. newlineCapacitor-less bifilar coil based IH system has been examined to feed power to newlinesingle load. The detailed analysis on the magnetic flux and temperature distribution newlineare carried out using COMSOL Multiphysics software. The performance of the bifilar newlinecoil based IH system is tested with various modulation techniques and the responses newlineare recorded in terms of heat rate, efficiency and modular power loss. The efficiency of newlinethe bifilar coil based IH system is 89.6% at rated output power. On analysis, it is found newlinethat the bifilar coil based IH system holds good only for single load IH system and it is newlinerelatively hard to estimate the resonant frequency for multi load applications. newlineTo feed power to multiple loads, dual output half bridge series resonance inverter newline(SRI) is presented. The inverter is operated by multiplexing two switching frequencies newlineusing pulse density modulation (PDM) technique for power control. The simultaneous newlineand independent power control is performed using PDM control scheme and validated newlinein real time using PIC16F877A micro controller. The efficiency of dual output half newlinebridge series resonance inverter fed IH system is 91% at rated output power. newlineThree leg SRI fed multi load IH system is developed for handling three loads with newlinesimultaneous and independent power control. The PDM control logic is employed to newlinehandle one load and/or two loads and/or three loads simultaneously/independently with newlineconstant switching frequency. The temperature rise in the loads are studied for various newlinetime instances. The system has 91% efficiency at 100% DPDM and greater than 86% newlinefor remaining DPDM. A wide range of power control from 0 to 100% of the rated power newlineis feasible with this technique