Power conversion circuit having improved zero voltage switching

摘要

A highly efficient and simple power conversion circuit (300) having zero voltage switching (ZVS) includes a novel switch timing technique, such that the need for an leakage inductor connected in series with the primary circuit of the converter and rectifier diodes is eliminated. A switch timing circuit (351) located in an output side circuit (350) enables the use of the natural stored magnetic energy in the output side circuit (350) to drive the critical switching transitions to accomplish soft switching for all of the switches (314-317) in a full bridge forward converter (300) for all transitions. This power conversion circuit (300) includes a full bridge circuit (310) having plurality of switching devices (314-317) that intermittently couple the primary winding (327) to the input of the power converter (300). A transformer (326) couples to receive power from the full bridge circuit (310) into its primary winding (327). The output side circuit (310) includes the switching circuit (351) coupled to provide stored magnetic energy to drive the switching transitions of the switching devices (314-317) in the full bridge circuit (310). The switching circuit (351) closes at a predetermined time delay after the switching transitions in the full bridge circuit (310) to accomplish zero voltage switching for the plurality of switches in the full bridge circuit (310). A converter controller provides control signals to the full bridge and the switching circuits (310, 351).