DAB-Based Common-Mode Injection in Three-Phase Four-Wire Inverters

Three-phase four-wire DC/AC converters are crucial for applications like electric vehicle (EV) chargers and solid-state transformers (SST). For ensuring galvanic isolation, dual-active-bridge (DAB) converters are often selected to be associated with the front-end AC/DC stage. In this context, this paper explores the possibility of delivering and driving the additional neutral wire directly from the DAB converter without introducing any additional and dedicated fourth-leg, as well as an independent-controlled neutral module. Further, a modified single phase-shift strategy capable of providing common-mode injection is presented and discussed under different operating conditions and modulation schemes. Finally, numerical results are presented to validate the correctness of all developments.