Closed-Form Continuous Asymmetrical Hybrid Modulation, Ensuring Wide ZVS Range and Seamless Transients for DAB Converters

This article introduces the closed-form continuous asymmetric-pulses–asymmetric-zeros (C2APAZ) hybrid modulation for dual-active-bridge converters, aiming to extend the ZVS range with minimal penalty in the rms current. The C2APAZ hybrid modulation combines symmetrical and asymmetrical modulation modes, utilizing five control variables. Closed-form continuous equations for these control variables are derived based on the switches' turn-
on
current. Optimization is conducted by controlling these currents, leading to an extended ZVS range. Experimental results from a 5000-W hardware setup demonstrate a 1.2% efficiency improvement at 500 W and a 0.72% efficiency improvement at 3500 W compared to the state-of-the-art asymmetrical hybrid modulations. In addition, a 5000-W power step is applied, and the proposed method illustrates the continuous transition of hybrid modulation modes throughout the power range, leading to a seamless transition.