The phase-shift controlled series resonant high frequency inverter has attracted growing interest as an induction heating and plasma production for basic research and industrial application. In general, the phase-shift controlled series resonant inverter by using the resonant current tracking or adaptive control scheme have excellent characteristics for power regulation and soft-switching operation. However, the inverter resonant frequency fluctuation by influence of switching disturbance in a resonant state is a problem of great proportions from a practical point of view. This paper deals with a newly developed phase-shift controlled ZCS (Zero Current Switching) inverter, which consists of the duplexed series resonant circuit topology that is suitable for high-frequency operation in Megahertz (MHz) switching range. In accordance with the discussion of frequency fluctuation in phase-shift controlled resonant inverter, we explained the operation of duplexed resonant circuit topology to reduce the frequency fluctuation. Furthermore, the design method of this proposed circuit is also described. Feature of this proposed circuit topology is described by using the computer simulation and experimental results.
