Snubberless boost full-bridge converters: Analysis of soft switching performance and limitations

摘要

This paper analyses current-fed (current source) isolated dc-dc converters that are proposed for various renewable energy and dc microgrid applications, such as photovoltaic, fuel cell, or energy storage systems. The analysis addresses current-fed (boost) full-bridge converters that achieve clamping and soft switching without dedicated external auxiliary circuits, such as snubbers or clamps. Such converters have certain limitations that can lead to degraded performance and feasibility due to high circulating energy or low silicone utilization at some operating points. The current study reveals these limitations, highlighting advantages and drawbacks of selected snubberless converters at different operating conditions. The relation between the rms input current and the isolation transformer primary current as well as the cumulative rms current of primary semiconductors is used as figure of merit for converter characterization. This approach can be extended and applied to other topology types and used as a universal tool for performance assessment of snubberless converters without auxiliary circuits for particular operating conditions in various systems.