Hatchable Solid State Transformer Rectifier Design through System Co-Optimization

Hepburn and Sons LLC teamed with North Carolina State University (NCSU) proposes an analysis of alternatives (AoA) to design and optimize a megawatt class, solid state transformer rectifier (SSTR) supporting maintainability of U.S. Navy shipboard power infrastructure. The design will convert 13.8kV AC to +-850V DC with modular, line-replaceable units (LRUs) that are compact and lightweight such that personnel may quickly and easily replace a hatchable failed unit. The design will improve maintainability, reduce costly access cuts, and improve system availability with potential at-sea replacements using onboard LRU replacements. The distribution interconnection of the SSTR design will readily support given shipboard applications which could include integrated warfare systems (IWS), energy storage charging, and pulsed DC loads such as directed energy. The team proposes an analysis of alternative SSTR topologies, implementing for each design a multi-objective optimization of converter topology, device, and magnetics selections. The designs will be optimized for thermal management, space, and weight requirements for a dramatic reduction of the current system’s mean time to repair (MTTR). A Phase I design concept will explore design options while evaluating mean time to failure of LRUs, ease and cost of LRU replaceability, and system performance against military standards. The team will leverage extensive wide band gap (WBG) device characterization and evaluation experience to determine optimal combinations of topology and semiconductor device selections. Coupling this data with extensive experience modeling and characterizing high power magnetics, the project team will provide co-optimized converter and magnetics design solutions for down selection. Through 3D renderings, the team will demonstrate the proposed LRU segmentation showing the plug-and-play ease of rackable modules. The transformer design will enable arc free, and toolless interconnects between high and low voltage LRUs, allowing hot swap replaceability of failed LRUs. Through multiphysics, electro-thermal modeling, attention will be placed on LRU compartmentalization with requisite thermal management to ensure mechanical robustness and cooling while minimizing weight. Design selection of the cooling methodology can enable further options in compartmentalizing functions to maximize replaceability of the design. The team will combine FEA work with 3D renderings to visualize the proposed converter design in hatchable LRU form. All analysis will support plans for Phase II prototyping and validation testing per military performance specifications. To ensure compliance with performance specifications, the team will apply extensive experience in military qualification testing, mapping out transition to U.S. Navy integration.