Closed-Form Continuous Asymmetrical Hybrid Modulation, Ensuring Wide ZVS Range and Seamless Transients for DAB Converters
Morteza Mahdavifard, S. Ali Khajehoddin
Abstract
This paper introduces the closed-form continuous asymmetric-pulses-asymmetric-zeros (C2APAZ) hybrid modulation for dual-active-bridge (DAB) converters, aiming to extend the ZVS range with minimal penalty in the RMS current. 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 5000W hardware setup demonstrate a 1.2% efficiency improvement at 500W and a 0.72% efficiency improvement at 3500W compared to the state-of-the-art asymmetrical hybrid modulations. Additionally, a 5000W 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.