A Boost Type Resonant Forward Converter With Topology Combination

This brief proposes a combined topology achieve duty ratio control for a resonant forward converter. Instead of directly cascading a boost converter with a resonant forward converter, the new circuit simultaneously fulfills voltage step up and isolated resonant power conversion by using a shared MOSFET and a shared diode. The main attraction is that simpler structure is utilized to achieve the performance feature of a two-stage circuit, and higher power efficiency is achievable due to reduced power conversion stages and power losses. Then, output voltage regulation is properly maintained by controlling the duty ratio, and a lower ratio between the leakage inductance and the magnetizing inductance is also allowed. In addition to detailed theoretical analysis, experimental results verify the feasibility of the proposed concept.