Single-stage multilevel ac/dc conversion using monolithic bidirectional switches

The recent invention of the Gallium Nitride (GaN) based monolithic bidirectional switch (MBDS) has unlocked new possibilities for power converter topologies and revamped interests in old topologies that have great theoretical merits but were deemed unattractive due to lack of access to MBDSs. This paper experimentally demonstrates a new power conversion topology (called the Cascaded Resonant Bridge or CRB) using such MBDS GaN transistors. The core of this topology is an isolated resonant dc-dc converter with high control bandwidth that can be connected in series/parallel/cascade to synthesise scaled-up ac or dc voltage (and power) as required. Theoretical and experimental works give evidence that the CRB can be a drop-in replacement for the widely used cascaded H-bridge (CHB) circuit with one less power conversion stage.