Abstract: To improve the present status that insufficient attention has been paid on the feature of zero current turn-off applying to the diodes which act as the rectifiers,and minimize the switching loss of the converter,this paper presented the methodology that can determine whether the zero voltage turn-off for a diode is achieved,via the theory analysis and example explanation,based on the definition of zero current turn-off. This paper also concluded the two practical ways to realize zero current turn-off for the rectifier diodes. Furthermore,a family of novel topologies which feature in zero voltage turn-on for the inverting switches and zero current turn-off for the rectifiers was proposed,via the deviation of topologies. Every member of this topology family is snubber-free,thus they are very suitable for the bidirectional DC-DC converters. A prototype,which can be applied in the uninterruptible power supply （UPS） system,verified the validity of the family of the snubber-free topologies and its superiority if implemented into practical applications.