This thesis investigates the design, modeling, and testing requirements of Medium Frequency Transformers (MFTs) for Solid State Transformer (SST) applications, with a focus on insulation coordination, thermal performance, and compliance with international standards. SSTs are gaining traction as a next-generation solution for power distribution, offering size and weight reduction, galvanic isolation, and seamless integration with renewable and bidirectional power systems. Central to their viability is the MFT, which must withstand high-frequency electrical and thermal stresses.

A 25kW, three-phase MFT operating at 1kHz was designed using copper windings and a Metglas core, achieving 98% theoretical efficiency and a target mass of 50kg. Detailed electromagnetic and thermal models were developed and validated through experimental testing on a single-phase air-core prototype, assessing insulation withstand, partial discharge behavior, and thermal rise.
The thesis also evaluates IEC 60076-11 as a baseline for MFT testing. While many procedures remain relevant, modifications are necessary to reflect high-frequency effects and pulsed excitation typical of SST systems. Recommendations are provided for adapting key tests to SST environments. This work contributes to bridging the gap between traditional transformer practices and the emerging demands of solid-state-based power conversion, supporting the future standardization and deployment of SST-compatible MFTs.