Three-level switching cell for low voltage/high-current dc-dc converters

New three-level switching cell converter topologies are proposed for transformer isolated low voltage/high current output dc-dc conversion. When compared with corresponding conventional converters without the three-level switching cell, the proposed converters operate with smaller current ripple and reduced voltage stresses. Alternatively, the current ripple size can be kept the same and the filter inductor value can be reduced for higher slew rate. First, the operation principles of these converters are described. Then converter design, control implementation and applications are presented. The capacitor charge balance problem is also addressed. Circuit simulations and experiments verify the basic operation of the new converters and their efficiency improvement. Index Terms--Synchronous rectification (SR), voltage regulator modules (VRM).