At present, limited work has been reported on the triple-active-bridge (TAB) converters containing the current-fed full-bridge terminal. The reason is mainly due to the commutation issue of leakage-inductor current in the current-fed full-bridge. To address this issue, an optimized modulation scheme is proposed in this letter. It can realize soft-commutation of leakage-inductor current, soft-switching operation and minimized circulating current simultaneously. The experimental results validate the effectiveness of the proposed scheme.