Naturally Clamped Soft-Switching Current-Fed Three-Phase Bidirectional DC/DC Converter

A novel bidirectional snubberless naturally clamped soft-switching three-phase current-fed dc/dc converter is proposed. A proposed secondary modulation technique naturally clamps the voltage across the primary-side devices with zero-current commutation, eliminating the necessity for active-clamping circuits or passive snubbers and solving the traditional problem of device turn-off voltage spike. Switching losses are reduced significantly, owing to zero-current switching of primary-side devices and zero-voltage switching (ZVS) of secondary-side devices. Soft switching and natural voltage clamping are inherent and load independent. The proposed bidirectional converter achieves high efficiency, high density, high reliability, small volume, light weight, and low cost compared to the active-clamped ZVS counterpart. Steady-state operation, analysis, and design of the proposed topology are explained. Experimental results are demonstrated to verify the natural clamping, soft switching, operation, and analysis.