Development of a Simple Direct Switched-Capacitor Ac-Ac Converter Using Cascade Connection

In this paper, we propose a simple direct AC-AC converter with cascade connection by using switched-capacitor (SC) techniques. The proposed AC-AC converter is synthesized with n (= 1, 2, ... ,N) converter blocks, where each converter block realizing 1/2x step-down conversion consists of only two capacitors and four switches. Unlike conventional SC converters, power conversion of the proposed converter is achieved without a flying capacitor. Hence, the proposed converter can reduce circuit size from the conventional converters. Furthermore, high conversion ratio is realized by connecting these converter blocks in series. In other words, multiple conversion is performed by cascade topology. To evaluate the effectiveness of the proposed converter, we conducted simulation program with integrated circuit emphasis (SPICE) simulations and theoretical analysis concerning power efficiency and input power factor. The evaluation demonstrated that the proposed converter can achieve better performance than the conventional converter using a flying capacitor.