Multifrequency Single-Stage Hybrid Switched-Capacitor Converter

The hybrid switched-capacitor converter (SSC) has unique advantages in the application of high-fixed-ratio dc-dc conversion. To meet the requirements of the load or input fluctuation range, the fixed-ratio hybrid SSC needs to build a two-stage structure with the traditional dc-dc converter. This article presents a multifrequency single-stage hybrid SSC with a modular design. The conventional resonant switched-capacitor circuit and buck circuit are modularly improved; different modules can operate at different frequencies. Modules with different operating frequencies are combined by means of the switched-capacitor structure. By increasing the switching frequency of the mixed switched-capacitor part in the prototype, the volume and weight of the passive components are significantly reduced, and the power density is improved. In addition, the frequency of the hard switching part is kept lower, reducing the switching loss of the inverter and improving the system efficiency. An experimental prototype consisting of two modules with a step-down ratio of 3-7 is constructed. The peak efficiency of the prototype reaches 96.79% at 48-V input.