Average Modeling of Dual Stage Solid State Transformer Power Electronic Building Blocks

Power electronic building block (PEBB) based solidstate transformers (SSTs) are attractive for shipboard applications due to their power density, controllability, and modularity. Circuit simulations of SSTs based on switch-level simulation for each PEBB are typically slow due to the high parts count, number of switching states, and complex interactions between converters. Average-value models (AVMs) of power-converters can enhance simulation speed, enabling system level studies of an SST for control design, design optimization, and even full-ship electrical plant models. This paper presents an enhanced average-value modeling (AVM) approach for a PEBB composed of a multilevel active neutral point clamped (ANPC) AC/DC stage and a dual active bridge (DAB) DC/DC stage. The proposed model incorporates loss and dead-time effects while maintaining computational efficiency. The trade-offs between different AVM approaches for each stage are analyzed. The AVMs are then integrated into a combined PEBB model with closed loop control demonstrating the suitability of the proposed models. The AVMs reduced the simulation time for the closed-loop model by 85 % compared to a fully switched model, highlighting the approach is suitable for integration into a complete SST model and full-ship electrical plant models.