This paper proposes a discrete-time model for dual active bridge (DAB) converters by taking the delay of micro-controller units (MCUs) into account based on the subsampling mode. The proposed model addresses the issue of traditional discrete-time model which cannot accurately reflect the delay effects on dynamics introduced by calculation and phase shift modulation. The proposed model is compared with various existing small-signal models including reduced-order model, generalized averaging model, traditional discrete-time model, and the accuracy is verified through computer simulation.