CAREER: Multi-level Bridge Tapped Resonant (MBTR) Solid-State Transformers (SSTs)

Solid State Transformers (SSTs) play a critical role in various applications for a sustainable future including integrating renewable energy and energy storage into modern electrical grids, electrified transportation systems, buildings etc. These applications require SSTs to comply with grid integration standard IEEE 1547, have the agility to deal with very abrupt load changes with high energy conversion efficiency over a wide load range. Present SSTs fall short of meeting these needs, having remained virtually unchanged since their inception. This necessitates the need to rethink the realization of SSTs, leading to the introduction of a family of new AC-DC bidirectional power converter topologies and control strategies to perform power conversion at higher switching frequencies with reduced component count and size for a wide range of applications. Simultaneously, the proposed approach takes full advantage of emerging Wide and Ultra-Wide Band Gap (WBG and UWBG) power semiconductors and innovations in magnetic materials for power conversion. A tightly-coupled educational plan supports the national priority to create renewable energy systems-based jobs through a power electronics workforce training program that includes students from diverse backgrounds and includes outreach to community colleges, public high schools, and Native reservations. The outcomes contribute to a sustainable future by reducing the cost and complexity of integration of renewable energy, reducing power conversion losses in such systems and transforming the charging infrastructure for electrified transportations, thus increasing their range and payload. This project engages in fundamental research to realize a new family of WBG and UWBG device-based, SSTs. The anticipated outcomes include 1) discovery and validation by analysis, prototyping, and testing of a new family of reduced device count, soft switched, high frequency, light weight fault-tolerant non-modular and modular power and voltage scalable SSTs naturally conforming to IEEE 1547; 2) unique multi-carrier space vector modulation and control techniques for the new SSTs; 3) novel additive manufacturing techniques for high temperature nano-crystalline integrated magnetics for SSTs. The new SSTs will have 25% fewer devices compared to state of art, will be 30% cheaper, 40% more power dense, and 5% more efficient resulting in a more sustainable future. In applications to battery energy storage alone, which is expected to expend to 4000 Tera-Watt Hours by 2030 in the US, the new family of SSTs will reduce the losses during power conversion by about 400 GWatt-Hours. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.