A two-stage topology for 24V input low voltage high current DC/DC converter

Abstract

A two-stage topology which is very suitable for 24V input, low voltage and high current output DC/DC converter is proposed. The first stage is two-phase interleaved Boost for regulating voltage, and the second stage is a fixed 50% duty cycle full-bridge (FB) for isolation and power transmission. To show its advantages in loss reduction, two topologies are also introduced for loss comparison. One is full-bridge which is typically used in industry, and the other one is two-phase-buck+full-bridge (TPBuck+FB). Through loss analysis and comparison of the three topologies mentioned above, we can easily come to the conclusion that the newly proposed topology could get higher efficiency than conventional topologies, especially under the condition of high power and low input voltage. Moreover, the magnitude of input current ripple is partly canceled because of two-phase interleaving operation of first stage, which means the size of input filter can be accordingly reduced. An experimental prototype using the new topology has been made to identify its high efficiency and high power density.