General High-Frequency-Link Analysis and Application of Dual Active Bridge Converters

High-frequency-link (HFL) electrical quantities, including high-frequency voltages, currents, and instantaneous power, are closely related to the performance of dc-dc converters. However, HFL electrical quantities are usually square, triangular, or trapezoidal waves and conventional indicators like apparent power or power factor are with vague physical meaning. This article gives a general HFL analysis to guide the optimization of dual active bridge converters (DAB). Novel indicators are proposed to describe the instantaneous power characteristic, which show better accuracy and reliability than the conventional indicators. Optimization objective construction method and hybrid optimization algorithm are proposed to calculate the optimal control coordinate, and the efficiency of DAB is enhanced for most of the operation points. Besides, the novel indicators and optimization objective are also good at the estimation of efficiency. Finally, experimental results verified the validity of the HFL analysis.