Dynamic Modeling and Closed-Loop Control of a Solid-State Transformer (SST) Based on Series Resonant Converter (SRC)

In this article, dynamic modeling and associated closed-loop control of a cascaded H-bridge (CHB)-based solid-state transformer (SST) with series resonant dual active bridge (SRDAB) as a high-frequency link isolation is proposed. The SRDAB converters are operated at resonant frequency in an open-loop fashion. The proposed integrated modeling of the SST incorporates important nonidealities of the system, which in turn reveals a simple yet rugged control of the entire SST system. The crux of the proposed control architecture is to regulate the low-voltage dc (LVDC) bus voltage by sensing only three high-voltage (HV) side dc-bus voltage of the input H-bridge cells. The proposed control technique is also extended for the SST system where the LVDC bus is remotely placed. The control technique does not require information of the LVDC bus voltage though there may be sufficient resistive drop in the SRDAB section and long cable drop in case of a remotely placed LVDC section. The proposed controller is easy to realize but takes care of all the inherent dynamics of the system. The feasibility of the proposed control technique is validated experimentally on a 1.65-
$kV$
/300-
$V$
, 8-
$kW$
SST system.