Resonant converter transformer design and optimization

Abstract

A new, low-profile, low-loss resonant converter transformer is proposed. Its design allows the absorption of the series inductor of the resonant converter through its leakage inductance. The windings are concentric with ferrite between them to control the leakage inductance. This arrangement offers electromagnetic interference (EMI) reduction compared to similar designs. Design software which optimizes the transformer inclusive of all of the resonant converter's load conditions is described. A design optimization for a 550 W inverter with a 20 mm tall transformer is presented and the resulting prototype is discussed. The results of large-signal power loss experiments are provided and indicate that measured results match well with predictions. Under reactive load, the results indicate an expected transformer efficiency of at least 98.20% at a load condition similar in magnitude to an actual operating point of the converter.