Series resonant high frequency inverter with zero current switching pulse density modulation for induction heated load

This paper presents the two lossless auxiliary inductor assisted voltage source type half bridge series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. This high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide power regulation ranges and load variations under its constant frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally presented for a constant high-frequency PDM control strategy under a ZCS operation commutation, together with its output effective power regulation characteristics-based on the PDM strategy. The experimental operating performances of this voltage source ZCS-PDM high frequency inverter using IGBTs are illustrated as compared with computer simulation ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The effectiveness of this high frequency inverter appliance is proved from the practical point of view.