Reduction of Switching Power Losses for ZVS Operation in Switched-Capacitor-Based Resonant Converters

This article proposes a new method for the switched-capacitor-based resonant converter (SCRC) consisting of two-half bridge circuits and a series resonant circuit. The proposed method controls the switching frequency, phase-shift angle, and deadtime to turn the MOSFETs off with a minimum turn- off current and to turn them on with zero voltage, resulting in the reduction of the switching power losses under both light and heavy load conditions. The gate signals for the two half-bridge circuits are mathematically derived based on the electrical charge and/or energy stored in the switched capacitor and the resonant inductor. The experimental results obtained from a 3-kW, 350-kHz SCRC prototype showed that the proposed method exhibited a high maximum power conversion efficiency of 99.5%, and it maintained a proper zero-voltage switching operation at a wide output current range from 17% to 100% with a conversion efficiency higher than 98.8%.