Efficiency comparison of the full bridge converters in considered magnetic saturation

Abstract

The operating efficiency of the full bridge converters via one and two output inductors was evaluated and analyzed based on the same power devices, magnetic components, output voltage ripple and switching frequency, is presented in this paper. Since the core losses of the output inductor and primary MOSFET ZVS performance will be affected by the output inductance at different load currents, the operating efficiency of the full bridge converter will be deteriorated without proper consideration the magnetic saturation characteristics of the core material. In order to take account the magnetic saturated effects of the core material, a nonlinear inductance model is used. As a result, the output current ripple and AC flux density variation at a different load current can be estimated more accurately in the design evaluation stage. After formulating the power losses of the key components, the operating efficiency of the 800W/12V/66A full bridge converter is estimated. From the estimated results, the one output inductor scheme has smaller power losses in the full CCM load range through proper design output inductance based on the output voltage ripple. Furthermore, the converters were further built and the experimental results were coincident with previous estimation. Finally, some simulation and experimental results are provided to demonstrate the effectiveness of this study. © 2008 IEEE.