Comparative Analysis of the Dual-Path Hybrid Switched-Capacitor DC-DC Converter and the 3-Level Buck Converter

Dual-Path (DP) DC-DC converters have been proposed as an alternative to traditional hybrid switched capacitor (SC) converters that can operate with a smaller, lower-quality, or higher effective series-resistance ESR inductor. The dual-path approach uses a partially hard-switched flying capacitor to reduce DC inductor current and associated resistive conduction losses. However, the SC hard-charging losses and higher inductor current ripple can partially or completely offset the advantage of reduced inductor DC current depending on the operating conditions and component parameters. In this work, we develop a unified model for all four 2:1 SC-based DP converters that captures SC hard-charging loss and inductor conduction loss as a function of conversion ratio, switching frequency, flying capacitance, and inductor ESR with fixed-volume inductor scaling. While there are regimes where the DP approach has advantages, there are also many scenarios where the traditional hybrid approach outperforms the respective dual-path alternative.