New phase-shifted soft-switching PWM high-frequency series resonant inverters topologies and their practical evaluations

This paper is concerned with a novel control scheme for full-bridge series-resonant phase-shifted PWM inverter. This control scheme is based upon varying inverter frequency adaptively according to load circuit parameters and phase-shifted angle φ. As a result, switching losses and stresses are minimized under phase-shifted power regulation. High frequency series-resonant inverters using this control technique and static induction power devices are practically applied to a 30 kHz-500 kHz high-power induction heating and melting power supply. The trially-produced inverter breadboards using static induction transistors are successfully demonstrated and discussed from a practical point of view. Finally, zero-voltage soft-switching effects of lossless capacitive snubbers are mentioned for an inverter circuit design which is incorporated into one switching leg of the full-bridge configuration