Direct buck-type AC/AC converter based on switched-capacitor

Switched-capacitor (SC) converters — mainly non-isolated DC-DC converters — have been a very important research topic for many years. Recently, switched capactitors have also been applied in direct AC-AC conversion, and studies have presented two different bidirectional SC ac-ac converters, which intended to replace the conventional auto-transformer in commercial and residential applications. The analysis of one of the presented converters shows that, by sacrificing the bidirectionality, the circuit can be shortened, resulting in a reduction of its overall cost and size. The proposed change modifies the behavior of the converter in each operational stage, thus a new analysis is needed. Therefore, this paper studies, describes, analyzes, designs and tests the proposed new topology. The paper also compares the new converter with the previous topology and presents its advantages, disadvantages and applications. In order to demonstrate the performance of that converter, the design example and experimental results of a prototype of 1 kW, 220/110 V input/output voltages, and switching frequency of 100 kHz, are reported herein. The maximum and nominal efficiencies shown by the prototype were 97.6% and 96.1%, respectively.