Dual active bridge modulation with complete zero voltage switching taking resonant transitions into account

The paper proposes an optimized modulation scheme for the Dual Active Bridge (DAB) converter topology, ensuring complete Zero Voltage Switching (ZVS) over the whole operating range. At first, ZVS limits for the modulation scheme in use are evaluated, taking the effect of resonant commutations into account. A strategy to achieve ZVS over the whole operating area is then proposed. A simple procedure to analytically calculate the switching pattern is presented, achieving high conversion efficiency without using complex loss models. Performance of the proposed control system is evaluated by actual measurements on a 2 kW DAB prototype, showing that complete ZVS is obtained over the whole operating range of the converter, resulting in high conversion efficiency even in the case of light load and buck/boost ratio considerably different from unity.