Power Control of Series-Parallel Resonant Inverter For Induction Heating Using Buck Converter

Abstract

The purpose of this work is to study, analyze, and design a half-bridge seriesparallel resonant inverter for induction heating applications. A pulse width modulation (PWM)-based double integral sliding mode voltage controlled buck converter is proposed for control the induction heating power. This type of controller is used in order to obtain very small steady state error, stable and fast dynamic response, and robustness against variations in the line voltage and converter parameters. A small induction heating coil is designed and constructed. A carbon steel (C45) cylindrical billet is used as a load. The induction heating load parameters (R L and L L ) are measured at the resonant frequency of 85 kHz. The parameters of the resonant circuit are chosen for operation at resonant. The inverter is operated at unity power factor by phased locked loop (PLL) control irrespective of load variations, with maximum current gain, and practically no voltage spikes in the switching devices at turn-off, therefore no snubber circuit is used for operation at unity power factor. A power MOSFET transistor is used as a switching device for buck converter and the IGBT transistor is used as a switching device for the inverter. A complete designed system is simulated using Matlab/Simulink. All the electronic control circuits are designed and implemented. The practical results are compared with simulation results to verify the proposed induction heating system. A close agreement between simulation and practical results is noticed and a good performance is achieved.