Analysis and Design of Four-Leg Fuel Cell Boost Converter

This paper presents the design and development of a four-leg fuel cell boost converter. For reduction of fuel cell current ripple, the converter always operates in continuous conduction mode (CCM), and is used with interleaved technology to meet specific ripple factor limitation for fuel cell currents. The design consideration of input inductors L plays a critical role for the ripple current reduction, while output capacitors C for a specified output voltage are designed with the considerations of leg number, switching frequency, output loads, and dynamic response. Equivalent models of the proposed converter are built for system analysis and compensation design. Intersil ISL6556A is used to implement control kernel to execute current-sharing algorithm and interlace triggering signals on each switch of the proposed system. Finally, the experimental results of a 1000 W prototype are given to justify the analysis of efficiency, current sharing tolerance, and current ripple factor. The Experimental results show that the four-leg converter in CCM can have lower ripple factor than its two- and three-leg counterparts, and meet the typical limitation of fuel cell output current ripple factor to be less than 4%