Soft Switched Synchronous Rectifier with Phase-Shifted Full Bridge Converter and Its Small-Signal Analysis

摘要

By using the output inductors and body capacitances without adding any component compared with hard switching synchronous rectifier, the topology of a soft switched synchronous rectifier with phase-shifted full bridge zero voltage switching DC/DC converter is proposed. The converter efficiency is maximized due to soft switching of the full bridge MOSFETs and the synchronous MOS-FETs, and also the low conduction loss of synchronous MOSFET. The operation principles of the circuit are analyzed in detail and the small-signal model is derived, also the converter dynamic characteristics are analyzed. Frequency responses of transfer functions under different values of transformer primary leakage inductance are discussed. The experimental results were obtained from a 400 V input and 100 A/12 V output DC/DC converter operating at 100 kHz. The results show that the converter efficiency is 2 percent higher in rated power than traditional diode rectifier.