Comprehensive Optimization Modulation Scheme of Low Current Level and Wide ZVS Range for Dual Active Bridge Converter with Dead-Zone Control

Due to the contradiction between low circuit current andwide zero-voltage switching (ZVS) range, for dual active bridge (DAB) converters, optimization schemes only aiming at minimum current will inherently induce a large switching loss. To extend the ZVS range while ensuring a low current level over the whole power range, this article proposes a comprehensive efficiency optimization scheme with triple-phase-shift in buck and boost modes of converters. Distinct from the previous modulation schemes, the proposed scheme is a multiobjective optimization based on the accurate ZVS constraints, and it is implemented in combined with the dead-zone control. To explore the accurate ZVS constraints, this article quantitatively analyzes the commutation process of switching devices in dead-band and comprehensively considers the influence of secondary-side voltage and parasitic capacitances. Based on this, a comprehensive optimization of current level and ZVS range is presented. And through the Lagrange multiplier method, a close-form global optimal solutions are obtained to realize the real-time control across a wide load and voltage ranges. Meanwhile, to further ensure a complete ZVS process and avoid the additional loss caused by reverse diode, the dead-zone control is also proposed to realize the dynamic adjustment of the dead time at different working conditions. Finally, a 1.5 kW laboratory prototype is built and the maximum measurement efficiency can reach 97.3% whenM=0.8 and 97.6% whenM=1.2, which verifies the feasibility and effectiveness of the proposed modulation scheme.