An Optimized Scheme for Current Stress Reduction with Zero-Voltage Switching in Dual-Active-Bridge Converters under Varying Input Voltage

This paper proposes an optimized extended-phase-shift (EPS) modulation to reduce the current stress in the dual-active-bridge (DAB) converters when the voltage ratio between primary and secondary sides is not matched with the turn ratio of its transformer. The proposed method can achieve the minimum peak current among possible solutions to achieve given power reference under whole power range and any voltage ratios. The realization of zero-voltage switching (ZVS) with consideration of the parasitic capacitance of the devices is also analyzed. This paper introduces a concept of minimal switching current to guarantee the ZVS in a specific power range. A small-scale experimental prototype was used to verify that this scheme is effective and practical.