The soft-switch PWM alternate-parallel dual-tube normal excitation converter belongs to DC converter in electric conversion device. Wherein, the one-way dual-tube normal excitation converter comprises source Vin, power switches Q1 and Q2, clamping diode DC1 and DC2, primary first winding NP1 of high-frequency isolating converter Tr and a first transformer leakage inductance Lr1; similarly, the another one-way dual-tube normal excitation converter comprises corresponding Vin, Q3 and Q4, DC3 and DC4, NP2 of Tr and Lr2; the output filter circuit comprises output rectifier diodes DR1 and DR2, output filter inductance Lf and output filter capacitor Cf. This invention keeps the ad vantage of low voltage stress and high reliability, increases the utility of magnetic core, needs no any active or passive circuit to realize the soft switch, has no circulation state to decrease on-state loss. |