Resonant Flying Capacitor Multi-Level Converter with Rerouted Capacitor for High Power Density and Efficiency

The conventional resonant flying capacitor multi-level (FCML) topology faces challenges in achieving high power density due to non-uniform phase durations, which limits the maximum output current. To address this, the proposed resonant FCML converter introduces a rerouted switched capacitor stage, ensuring uniform resonant phase durations and uniform peak phase currents. Utilization of the rerouted capacitor also reduces the equivalent series-connected switch resistance in the current path, leading to reduced conduction loss and enhanced efficiency. The proposed resonant FCML topology aims to address the limitations caused by non-uniform resonant frequency in conventional resonant FCML structures. It offers a promising solution for enhancing the power density and efficiency of the resonant switched capacitor topologies. The intended uniform resonant frequency operation is confirmed with a 48-to-12 V conversion FCML prototype. The experimental prototype achieves a maximum efficiency 98.3% and an efficiency of 95.2% at full-load efficiency with a power density of 1472W/in3.