High Efficiency Mechanism Analysis of Resonant Switched-Capacitor Converter

The switched-capacitor (SC) converters are gaining popularity in some practical use. Its resonant counterpart, with a small inductor as current shaper in the architecture, has the advantage of smoother charging current, smaller voltage and current variation ratio and so on. This paper presents a generic and thorough analysis of the efficiency mechanism of the resonant switched-capacitor converter (RSCC). It decomposes any RSCC into three basic sub-circuits of SRLC circuit, CRLC circuit and SRLC2 circuit, which are analyzed and compared with corresponding sub-circuits of SCC, respectively. Then the overall efficiency of a RSCC could be derived. Furthermore, a new calculation method of output impedance is developed in another perspective to reveal the high efficiency mechanism of RSCC. On this basis, the high efficiency operation condition for RSCC could be obtained. Finally, a resonant bridge modular switched-capacitor converter (RBMSCC) is proposed and built for example of extended implementation of RSCC to achieve high efficiency operation. Some useful comments for designing resonant switched-capacitor converters are suggested.