A Multi–Degree-of-Freedom Decoupled Power Control Strategy for a Single-Stage Resonant DAB Microinverte

Targeting severe control-variable coupling, high switching loss, and hard-to-suppress backflow power in single-stage resonant DAB microinverters, this work proposes a multi-degree-of-freedom decoupled power control strategy. First, a time-domain converter model is established. Under the zero-current condition, a decoupled mathematical model of the outer phase-shift angle at secondary switch turn-off is derived, yielding the time-domain relation between the outer phase-shift trajectory and the output current. Second, under soft-switching constraints, a coordinated trajectory equation linking the inner phase shift and the switching frequency is obtained. Based on these results, controller parameters are optimally designed by jointly considering soft-switching fulfillment, backflow-power suppression, and RMS-current minimization. The core is a multi-DOF decoupling model that enables independent regulation of the output current via the outer phase shift, thereby enhancing control flexibility, reducing switching loss, and suppressing backflow power. Finally, a 300 W laboratory prototype validates the correctness and effectiveness of the proposed strategy.