DC-DC zero-voltage-transition converter with PWM control and low stresses on switches

A new type of DC-DC power converter, which achieves soft-switching for all the active and passive switches, is presented. Its basic structure is that of a quasi-resonant power converter, with an additional two active switches and four diodes. The resonant capacitors are not discrete elements, the parasitic capacitances of the MOSFETs play the role of resonant capacitors. All switches are subjected to voltage and current stresses at the same level as those in their PWM hard-switching counterparts. The power converter exhibits high efficiency and large regulation capability, based on a duty-cycle control. The soft-switching condition is maintained for a wide line range and load range