Hatchable Solid State Transformer Rectifier Design through System Co-Optimization

Hepburn and Sons LLC, teamed with the North Carolina State University (NCSU), proposes to prototype, validate, and demonstrate a hatchable solid state transformer rectifier design based off the neutral point clamped converter topology, achieving modularized power capacity in a line replaceable unit (LRU) architecture featuring fully parallel MVAC inputs and DC outputs. The design converts 13.8kV AC to +-850V DC with modular LRUs that are compact and lightweight such that two personnel may quickly and easily replace a hatchable, failed unit. The design improves maintainability, reduces or eliminates costly access cuts, and improves system availability with potential at-sea replacements using onboard LRU replacements. The distribution interconnection design will readily support shipboard applications which could include integrated warfare systems (IWS), energy storage charging, and pulsed DC loads such as directed energy.  During the Phase I Base period, the team performed multi-objective optimization of converter topology, device, and magnetics selections. These considerations were also optimized for thermal management, space, and weight requirements for a dramatic reduction of the current system’s mean time to repair (MTTR). The design was down selected to a direct MV to LV conversion topology using a single-phase neutral point clamped active front end with dual active bridge. Co-optimization of a medium frequency (MF) transformer core design leverages advanced US based magnetic materials available from companies such as CorePower Magnetics and Metglas, Inc. Priority was placed on ease and cost of replaceability, operational mission availability, and alignment with military performance standards called out in the solicitation. The team is leveraging extensive experience and active projects in wide band gap (WBG) device characterization with demonstration experience for design co-optimization of topology and semiconductor device selections. Coupling this data with extensive experience modeling and characterizing high power, medium frequency magnetics, the project team is providing a co-optimized converter and magnetics design.