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


The purpose of this work is to study, analyze, and design a half-bridge seriesparallelresonant inverter for induction heating applications. A pulse width modulation(PWM)-based double integral sliding mode voltage controlled buck converter isproposed for control the induction heating power. This type of controller is used inorder to obtain very small steady state error, stable and fast dynamic response, androbustness against variations in the line voltage and converter parameters. A smallinduction heating coil is designed and constructed. A carbon steel (C45) cylindricalbillet is used as a load. The induction heating load parameters (RL and LL) aremeasured at the resonant frequency of 85 kHz. The parameters of the resonant circuitare chosen for operation at resonant. The inverter is operated at unity power factor byphased locked loop (PLL) control irrespective of load variations, with maximumcurrent 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 powerMOSFET transistor is used as a switching device for buck converter and the IGBTtransistor is used as a switching device for the inverter. A complete designed system issimulated using Matlab/Simulink. All the electronic control circuits are designed andimplemented. The practical results are compared with simulation results to verify theproposed induction heating system. A close agreement between simulation andpractical results is noticed and a good performance is achieved.