The Dual Active Bridge (DAB) topology is ideally suited for high-power dc/dc conversion especially for energy storage applications. Due to the low current ripple and higher conversion requirements, Current-Fed DAB (CFDAB) with secondary-side modulation is implemented to avoid the voltage spike across parasitic capacitance of Low Voltage (LV) switches. This paper details Phase Shift Modulation (PSM) and Phase Shift plus High Voltage Duty Modulation (PSDM) implemented to transfer the power and avoid voltage spike. A comparison between the two in terms of the power transfer, soft-switching conditions and transformer RMS and circulating currents are detailed. Also, to improve the efficiency of the converter at low load conditions, an Extended Phase Shift Modulation (EPSM) is proposed. The zero state in High Voltage (HV) transformer voltage is introduced by the phase shift between the cross-connected legs in HV. The phase shift between the legs reduces to zero at heavy loads and thus, the modulation shifts to PSM smoothly. The zero state reduces the peak current which thus, reduces the back flow power. The above Modulation analyses power transfer and transformer currents within the safe operation region of the converter. Simulation results are shown to validate the theoretical claims for full load and partial load conditions for PSM and EPSM.