Advanced zero-current soft-switching PWM and PFM hybrid controlled series load-resonant inverters for high-frequency electromagnetic induction-heating power supply and its performance evaluations

This paper deals with a new soft-switched circuit topology of the voltage-fed full-bridge type series load-resonant high-frequency inverter with lossless inductor snubbers incorporated into one of the switching bridge legs. The wide power regulation ranges under the condition of zero-current soft-switching operations are achieved for this unique topology and control strategy. The simulations of this inverter are analyzed and evaluated, when this inverter operates under the optimum condition of load-adaptive frequency modulated mode phase-shifted PWM hybrid control strategy. From the experimental results of the inverter system using lossless inductor snubbers and IGBTs, this inverter circuit topology designed for induction-heating is proved to be cost-effective for reducing switching losses, and its operating frequency can increase up to 100 kHz for IGBTs.