Capacitor-charging soft switching DC/DC transformer

This paper introduces capacitor charging soft switching DC/DC transformer (CSDT). Voltage and current waveforms of DC/DC Transformer are given, the relationship formulae for voltage and current changing with time in one switching period are deduced and in which the switching period is split up into four time zones, and the characteristics of zero voltage soft switching (ZVS) and the zero current soft switching with restriction are analyzed. The experiment circuit is completed and the simulation and verification of the model is preceded. The current waveform observed from second side of the high frequency transformer shows that there are fed-forward and fly-back energies in the output current of the converter at the same time zone. The results also show that the DC/DC transformer has good ZVS and a special property of loading character in a relative large area of duty ratio values, and it has a higher efficiency of power conversion and lower EMI.