A 1-kW Step-Up/Step-Down Switched-Capacitor AC-AC Converter

This paper proposes a new ac-ac static power converter based on the switched-capacitor (SC) principle, intended to replace the conventional autotransformer in commercial and residential applications. The principle of operation, a qualitative and quantitative analysis, the design methodology, and an example are described in this paper. The main advantages of the proposed ac-ac converter are the absence of magnetic elements, the stress voltages in all components being equal to half of the high-side voltage, the common reference between input and output voltages, the employment of a single SC leg, the ability to be bidirectional, the high efficiency, and the high power density. In order to demonstrate the performance of this converter in the laboratory, a prototype of 1-kW, 220-V-rms high-side voltage, 110-V-rms low-side voltage, and switching frequency of 100 kHz was designed and fabricated. The relevant experimental results are reported herein. The maximum and rated power efficiencies obtained in the laboratory were 98% and 96%, respectively.