An Efficiency-Oriented Two-Stage Optimal Design Methodology of High-Frequency LCLC Resonant Converters for Space Travelling-Wave Tube Amplifier Applications

Abstract

The high-frequency LCLC resonant converters are widely used in the two-stage power converter as a dc transformer for the space travelling-wave tube amplifier applications. In the two-stage power converter, since the output voltage is controlled by a preregulator, which is the first stage, the main functions of the high-frequency LCLC resonant converter, which serves as the second stage, are to boost the input voltage and to provide galvanic isolation while keeping high efficiency. As boosting the input voltage and providing galvanic isolation can be achieved by the transformer, achieving high efficiency is most challenging. Previous studies on the LCLC resonant converter mainly focus on reducing the switching loss. However, in addition to the switching loss, the total power loss of the LCLC resonant converter contains driving and conduction loss of the main switches; core loss, copper loss, and dielectric loss of the transformer; and the conduction loss of the rectifiers. As a result, low switching loss cannot guarantee the high efficiency of the LCLC resonant converter. To solve this problem, in this paper, an efficiency-oriented two-stage optimal design methodology of the LCLC resonant converters is proposed. In the first stage, the optimal parameters of the LCLC resonant converter, which aims at minimizing the total power loss of the converter, are found from the proposed genetic algorithm + particle swarm optimization algorithm. After that, in the second stage, a single-layer partially interleaved transformer structure is proposed to realize the optimal parameters. After the transformer design is finished, the optimal LCLC resonant converter is built. The proposed efficiency-oriented two-stage optimal design method and the transformer structure are validated by simulations and experiments.