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This article proposes a highly efficient current-fed half-bridge resonant converter over a wide range of the output voltages. By adding a bidirectional switch across center nodes of the voltage doubler and applying corresponding switching modulation, the converter accomplishes almost zero-voltage switching at the turn-off instant under the wide output voltage variations. Moreover, the circuit experiences very little instantaneous reactive current even when the output voltage varies widely. Primary-side duty cycle fixed at 0.5 balances the voltages across the capacitors at the primary side and at the secondary side each irrespective of the output voltage variation; it also limits the voltage stress at the active power components. Therefore, the proposed converter delivers high efficiency and compact component size. We fabricated a 400-W experimental prototype to validate the superior properties of the proposed converter.