Asymmetrical duty cycle control with phase limit of LLC resonant inverter for an induction furnace

Abstract

This paper proposes a power control of LLC resonant inverter for an induction furnace using asymmetrical duty cycle control (ADC) with phase limit to guarantee zero voltage switching (ZVS) operation and protect switching devices from spike current during the operation. The output power can be simply controlled through duty cycle of gate signals of a full-bridge inverter. With the phase limit control, non-ZVS operation and spike current caused by a change of duty cycle with fixed frequency and load Curie's temperature can be eliminated. Theoretical and simulation analyses of the proposed method have been investigated. The experimental results of heating a 300 g of Tin from room temperature until it is melted at 232 °C provided.