Modularized Diode Rectifiers: A New Family of Solid-State Transformers

Abstract

Solid-state transformers (SSTs) are conventionally based on a multistage architecture, with an input and/or an output ac/dc converter (for interfacing with the ac grid and/or the load), and with an isolated dc/dc conversion stage (to provide insulation and voltage/current scaling). Alternatively, some single-stage SST circuits use ac/ac conversion modules and rely on bidirectional blocking devices, which however have limited commercial availability and face significant operational challenges. This letter explains the derivation, operating principle, and fundamental topologies of a new family of SSTs, named modularized diode rectifiers. Their architecture is derived from the integration, within basic diode rectifier circuits, of dc/dc converter modules, which are fed by unipolar pulsating voltages. Despite using only dc/dc modules, this family of circuits can achieve isolated ac/dc and/or ac/ac conversion, can provide power factor corrector features, and can be easily scaled for higher voltage and/or current ratings.