Adaptive Dual-Side Phase-Shift Modulation for Complete and Decoupled Elimination of Transient DC Bias in DAB Converter

Transient DC bias inherently exists in dual-active bridge (DAB) converters during load transients. Although various mitigation methods have been proposed, transient DC bias current and flux still cannot be fully removed due to the difference in the time constant. This letter proposes a novel adaptive dual-side phase-shift modulation for DAB converters to achieve complete and decoupled elimination of transient DC bias current and flux. Distinguished from existing methods, the proposed method exploits both phase-shift angle direction and magnitude as independent control variables, enabling decoupled instantaneous flux balancing and transient peak current tracking. Consequently, both transient DC bias current and flux are fully eliminated despite the impact of AC-link resistance, allowing transformer current and flux to stabilize within one switching cycle. Experiments are conducted to validate the effectiveness of the proposed method.