Comparative evaluation of soft-switching, bidirectional, isolated AC/DC converter topologies

For realizing bidirectional and isolated AC/DC converters, soft-switching techniques/topologies seem to be a favourable choice as they enable a further loss and volume reduction of the system. Contrary to the traditional dual-stage approach, using a power factor corrector (PFC) stage in series with a DC/DC isolation stage, we showed recently that the same functionality can be achieved under full soft-switching operation using a single-stage dual active bridge (DAB) AC/DC converter. This paper investigates the performance of this single-stage approach by comparing it with a state-of-the-art conventional dual-stage concept (both soft-switching converters), where a bidirectional interleaved triangular current mode (TCM) PFC rectifier was chosen in combination with a DAB DC/DC converter. The advantages and drawbacks of each concept are discussed in detail, focusing on the impact of the utilized semiconductor technology and silicon area on the converter efficiency. Furthermore, a comprehensive comparison of power density is allowed by the analytical models that correlate the component losses with their respective volume.