Integrated magnetics for current-doubler rectifiers

This paper presents a new integrated magnetic structure for current-doubler rectifiers (CDR). Compared to previously published structures, the proposed design allows the equivalent filtering inductance to be increased with significantly less increase in total winding conduction loss. The increased inductance leads to reduced current and voltage ripple, thereby reducing the size of capacitors required for output filtering. The lower current and flux ripple also helps to reduce the conduction loss and the magnetic core loss. As the result, the overall converter efficiency can be improved, especially under light load when the losses due to ripple current and ripple flux are more significant. Analysis of the proposed structure is presented in the paper, along with an equivalent circuit model suitable for steady-state and dynamic response analyses. Detailed design procedures are also provided by using a half-bridge converter as example. Experimental results from two 100-W, 3.3-V output half-bridge converters are presented to validate the concept and the analyses.