Experimental validation of a proposal for a 3.5 kVA three-phase magnetic-less solid-state autotransformer (SSAT) based on the switched-capacitor principle

Abstract

This paper presents experimental results for a three-phase direct ac-ac converter based on switched capacitor principle in delta and wye configuration. This converter employs only capacitors and switches in the power stage, it has a fixed gain, it operates in open loop with constant duty cycle and constant switching frequency and the topology is bidirectional. One advantage of the proposed converter is a power stage with no magnetic elements, which makes the converter appropriated to build solid state autotransformers. A complete analysis of output voltages (phase-shift and amplitude) that are obtained regarding the delta and wye connections of converter is approached and it is corroborated with experimental results for resistive, inductive and nonlinear loads. A 220 V/110 V/3.5 kVA/100 kHz (in switching frequency) prototype was built and tested. For delta and wye connections of the modules, an efficiency of 90.4% and 95.05% was obtained in the rated load, respectively.