Piecewise Linear Model for Snubberless Dual Active Bridge Commutation

A dual active bridge (DAB) converter promises high power density. The highest power transfer can be achieved by phase shift modulation inside the zero-voltage switching boundaries. This paper analyzes the transients of DAB commutation. Although commutation has been previously analyzed for DAB with the linear turn-off snubbers, in today's industries, the output capacitors of the switches are utilized as the snubberless approach. The presence of these time-variant capacitors leads to nonlinear equations. This paper applies a piecewise linear model for analyzing the commutation of the ac-link current into the switches. The study is inspired by practical experiments, and the results are experimentally verified.