Analysis and Output Voltage Control of a High-Efficiency Converter for DC Microgrids

Abstract

Analytical evaluation and voltage control method of a cascaded step-up switched-capacitor converter (CSU–SCC) under zero current switching (ZCS) operation and continuous conduction mode is studied in this paper. The ZCS condition, which means operation below resonant frequency, makes the soft-switching operation of switching devices. Therefore, it increases the converter efficiency. In addition, due to operating in higher range of switching frequency, the size of proposed converter can be reduced (i.e., higher power density). Compared with the competitive topology of SCCs, it enables the output voltage regulation of the converter under ZCS. The proposed CSU–SCC provides a higher range of output voltage and power by proposing an exponential structure of an SCC. An analytical study is developed to calculate the output current and voltage characteristics of the converter. Based on the derived output voltage characteristic, a closed–loop voltage controller is proposed to regulate the output voltage of the CSU–SCC under different conditions. The simulation results for an input voltage 110 V-160 V and 500 W CSU–SCC converter verify the proposed analysis and the proposed voltage controller.