POWER CONVERTER WITH LOW DRAIN VOLTAGE OVERSHOOT IN DISCONTINUOUS CONDUCTION MODE

摘要

A power converter includes a primary side with switch devices (A-D) that form a power transfer stage, and a secondary side with switch devices (E1, E2, F1, F2) that form a rectification stage and an output filter (Lo, Co) coupled to the rectification stage and including an output inductor (Lo) and output capacitor (Co). A transformer (Tr) couples the primary and secondary sides. The switch devices (A-D, E1, E2, F1, F2) are controlled by a controller (106) in DCM (discontinuous conduction mode) to transfer energy from the primary side to the secondary side during a power transfer interval in which one branch of the power transfer stage is conducting, one branch of the rectification stage is conducting and another branch of the rectification stage is blocking. As a voltage of the transformer first begins to rise at the start of a new power transfer interval in DCM, the branch of the rectification stage that is to be conducting during the new power transfer interval is hard switched on.