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.