Multipurpose Universal Steady-State Model of Current-Fed Dual-Active-Bridge Converter Deciphering Its Accurate Behavior

This article develops a universal, accurate steady-state model suitable for the current-fed dual active bridge (CFDAB). Unlike a voltage-fed dual-active-bridge converter, modeling of the CFDAB converter is not straightforward due to the presence of additional buck/boost stage on the low-voltage side. This article presents for the first time exhaustive information on steady-state characteristics of the CFDAB for the entire operating region under pulsewidth plus phase shift (PPS) modulation. The steady-state behavior is obtained analytically using the harmonic state-space (HSS) model. The developed HSS model is advantageous over the popular generalized averaging method since it is easier to extend the former model to numerous high-order harmonics than the latter. The presented model outputs accurate steady-state waveforms. The model is used to study the characteristics of some important electrical quantities, such as peak current, rms current of the high frequency link, output current ripple, for the entire range of all degrees of freedom at one go. The exhaustive experimental results confirm the analytical model.