Design of a Solid-State Transformer in Pursuit of more Sustainable Power Electronics Solutions

Abstract

This thesis aims to explore the field of sustainable power electronics by attempting to design a solid-state transformer (SST) circuit to replace low frequency doorbell transformers. The idea is that by significantly increasing the frequency of the signal being transferred through the transformer using an SST topology, the required size of the transformer will shrink substantially, leading to savings in terms of manufacturing emissions. A brief overview of the sustainability of a couple of important components in terms of manufacturing emissions is performed before the proposed SST is designed to inform the selection of the transformer core, as well as all other components, and to allow the comparison of emissions between the low-frequency and SST devices for this application. An isolated Ćuk AC-AC converter with bidirectional switches is decided upon as the base topology for this SST design, and an analysis is performed to determine what components are needed to fulfill the application requirements. Further, the transformer is designed to ensure that it meets the specifications of the Ćuk converter. A control circuit as well as PCB are also designed to allow for the proper operation of the Cuk converter. The design proposed in this thesis was shown to be insufficient in terms of both emissions and cost compared to the currently used low-frequency transformer. This was mostly attributable to the heavy emissions profiles of the ICs, power transistors, and the PCB, as well as the high cost of the DC/DC converters which were used. Most of the emissions for these high emission components came from scope 2 emissions, in particular electricity consumption. As such, this paper finds that the ability to design more sustainable alternatives to low-frequency transformers is highly dependent on decarbonization of the grid.