High-Gain High-Frequency Three-Phase $LLC$ Resonant Converter Design Based on the Wye–Delta Transformer for Aircraft Applications
Daniel Ríos Linares, Alberto Delgado, Miroslav Vasić
Abstract
The requirements for small form-factor power supplies drive the need for high-frequency, small magnetic components and high efficiency to obtain thermal stability. When combined with high output power, magnetic optimization becomes crucial in the pushing of the boundaries of magnetic shrinkage. Among those applications in need of power dense systems, aircraft is considered one of the most restrictive due to its ultra-high reliability and miniaturization in both volume and mass. Critical on-board apparatus upstream the responsibility to the power stage classifying it as mission-critical. The selection of a multiphase converter enables the desired magnetic components shrinkage. With these objectives in mind, a Three-Phase LLC based on the wye-delta transformer is selected as a promising topology to fulfil high efficiency, small form-factor, effective power density and high voltage step-down in aircraft applications. The focus of this work is the listing of the guidelines on the design of the three-phase magnetic components with the compensation of an asymmetric structure (EE/EI cores) to match its magnetic coupling. The multiple sources of power losses are analysed and optimized, including the high-amplitude high-frequency currents traveling around the PCB. This paper presents the design of an unidirectional DC/DC converter with an input voltage range of 235-285 V to 28 V at the output, controlled by a frequency range of 15% for a nominal output power of 1 kW reaching 96% of efficiency.