Piecewise linear modeling of snubberless dual active bridge commutation

The 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 from practical experiments, and the results are verified experimentally.