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This paper contributes to the steady-state analysis of the bidirectional dual active bridge (DAB) dc-dc converter by proposing a new model that produces equations for rms and average device currents, and rms and peak inductor/transformer currents. These equations are useful in predicting losses that occur in the devices and passive components and aid in the converter design. An analysis of zero-voltage switching (ZVS) boundaries for buck and boost modes while considering the effect of snubber capacitors on the DAB converter is also presented. The proposed model can be used to predict the converter efficiency at any desired operating point. The new model can serve as an important teaching-cum-research tool for DAB hardware design (devices and passive components selection), soft-switching-operating range estimation, and performance prediction at the design stage. The operation of the DAB dc-dc converter has been verified through extensive simulations. A DAB converter prototype was designed on the basis of the proposed model and was built for an aerospace energy storage application. Experimental results are presented to validate the new model for a 7 kW, 390/180 V, 20 kHz converter operation and the ZVS boundary operation.
Date of Publication: Nov. 2012