Novel Interleaved Bidirectional Snubberless Soft-Switching Current-Fed Full-Bridge Voltage Doubler for Fuel-Cell Vehicles

This paper presents a novel interleaved soft-switching bidirectional snubberless current-fed full-bridge voltage doubler (dc/dc converter) for an energy storage system in fuel cell electric vehicles. A novel secondary modulation technique is also proposed to clamp the voltage across the primary-side switches naturally with zero-current commutation. It, therefore, eliminates the necessity for an external active-clamped circuit or passive snubbers to absorb the switch turn-off voltage spike, a major challenge in current-fed converters. Zero-current switching of primary-side devices and zero-voltage switching of secondary-side devices are achieved, which significantly reduce switching losses. An interleaved design is adopted over a single cell to increase the power handling capacity obtaining merits of lower input current ripple, reduction of passive components´ size, reduced device voltage and current ratings, reduced conduction losses due to current sharing, and better thermal distribution. Primary device voltage is clamped at rather low-reflected output voltage, which enables the use of low-voltage semiconductor devices having low on-state resistance. Considering input current is shared between interleaved cells, conduction loss of the primary side, a considerable part of total loss, is significantly reduced and higher efficiency can be achieved to obtain a compact and higher power density system. Steady-state operation, analysis, and design of the proposed topology have been presented. Simulation is conducted over software package PSIM 9.0.4 to verify the accuracy of the proposed analysis and design. A 500-W prototype has been built and tested in the laboratory to validate the converter performance.