Yu Jiang

TL;DR: In this article , the average model of the proposed converter topology and the grid-forming and grid-following control strategy based on two-phase independent control is discussed. And the smooth switching method of low-frequency four-phase to three-phase mode under line fault and operation maintenance conditions is analyzed respectively.

Abstract: The strong parameter dependency of model predictive control (MPC), despite its capability to enhance dynamic performance in dual-active-bridge (DAB) converters, remains a critical limitation. To overcome the parameters’ uncertainty of DAB, this article proposes a model-free predictive control (MFPC) method integrated with a sliding-mode observer (SMO). First, to enhance the steady-state efficiency of the DAB converter, optimization strategies for natural zero-voltage switching (ZVS) and full ZVS are proposed under the constraint of minimum current stress. A comprehensive analysis of the advantages and disadvantages of both methods is conducted, and the most efficiency-optimal approach is selected based on experimental results. Second, an ultralocal model of the DAB converter is established, which innovatively consolidates all uncertainties into a unified lumped disturbance. A full-order SMO is employed to estimate the lumped disturbance in real time, replacing traditional parameter identification techniques. This reduces computational burden while enhancing system robustness. Finally, experimental comparisons with other schemes validate the effectiveness and superiority of the proposed method.