Advanced modulations for a current-fed isolated DC-DC converter with wide voltage operating ranges

An Active-Bridge-Active-Clamp (ABAC) topology with its associated switching patterns and modulation techniques is introduced in this paper. The topology has been designed to comply with stringent power quality requirements in a More Electric Aircraft (MEA) application. The dual transformer secondary structure of the ABAC allows the definition of a particular phase shift based switching pattern. The proposed switching pattern ensures not only the output current switching harmonics elimination but also even power sharing between the secondary half bridges. Consequently, passives on the low voltage side of the converter are minimized and transformer DC bias is eliminated. All these features can be achieved independently from the operating point of the converter. In this paper, the basic operation of the ABAC converter is firstly introduced. Theoretical analysis of switching harmonics elimination and power sharing is then carried out in the development of the proposed switching patterns. The theoretical claims are validated by both simulation and experimental results on a 10kW 270V/28V ABAC converter.