Steadv-state characteristics of a novel forward-flyback-mixed converter

摘要

Based on the conventional forward converter, the transformer's magnetizing inductance is made small, and a reset winding of the transformer is moved to the secondary side, and furthermore, the anode terminal of the freewheeling diode is connected to a different point. Then a novel topology of DC-DC converter is proposed, and its power efficiency is predicted to be improved. This converter has both operations of forward and flyback manners, and both of two diodes in the output side are maintained to be ON for a portion of the switching period. This operation results in the reduction of current ripple in the output inductor. Furthermore this novel converter is confirmed to have a prominent feature such as the reduction of withstand voltage for the main switch. As a result, this converter obtains a higher efficiency over the conventional forward converter. This paper describes its basic operation, and analyzes the steady-state characteristics by means of the extended state-space averaging method. The analytical results are confirmed experimentally, and a high efficiency of 94% was obtained for the input voltage of 140V and the output load of 18V and 4A.