A Differential-Mode Isolated AC/AC Converter

In this article, an isolated single-stage direct power conversion (DPC) type ac/ac converter is outlined. The ac/ac converter is based on differential-mode (DM) architecture where two dc/dc converter modules are connected differentially. The pulsewidth modulation active-clamp-Ćuk converter is used for the DM modules as the converter allows zero-voltage-switching turn-on capability on all switches over a wide operating range, enabling the construction of a high-efficiency ac/ac converter. This article details the modulation scheme and the operational analysis of the new DM ac/ac converter (DMAC). In DPC-type ac/ac converters, the converter is required to propagate the input port electric signal to the output port with minimal internal energy storage. The capacitative component internal to the converter undergoes the ac voltage transition, which appears as a capacitive load resulting in reactive power injection in the input port. Hence, a thorough design process of the ac/ac converter is provided to minimize the internal capacitance of the converter. A 1-kW hardware prototype is also built using the underscored design process to validate and demonstrate the operation of the ac/ac converter.