Full soft-switching bidirectional current-fed DC-DC converter

The focus is on a switching control strategy for the galvanically isolated bidirectional current-fed dc-dc converter. The converter under study employs the current-fed full-bridge stage at the low-voltage side and the voltage-fed half-bridge stage at the high-voltage side. The current-fed side of the converter utilizes four-quadrant switches comprised of two MOSFETs each. The switching sequence proposed enables soft-switching operation of all switches in both directions of energy transfer for a wide range of dc voltage gain and load variations. Moreover, it features natural clamping and thus eliminates voltage overshoot at the turn-off of switches at the current-fed side. Full zero-current switching is achieved in the current-fed side, while full zero-voltage switching is accommodated in the voltage-fed side. Theoretical predictions were verified with simulations in PSIM 9.