A 15 kV class intelligent universal transformer for utility applications
This paper discloses the development of 15 kV class intelligent universal transformer (IUT) to show system level design, circuit topology, and prototype test results. The complete system is split into two stages: (1) high voltage ac to low voltage dc and (2) low voltage dc to low voltage ac. With the adoption of silicon carbide (SiC) devices, the high voltage front end ac to low voltage dc conversion stage achieves 98.4% efficiency, and the complete power stage can be naturally cooled. With the adoption of auxiliary resonant soft switching inverter, the second stage achieves 99.2% efficiency. Overall the system has been demonstrated at 97.5% efficiency without forced air cooling. Extended 8 hour testing was conducted to ensure long term operation reliability. Overall efficiency and voltage regulation were compared with that of a conventional transformer for justification of IUT adoption.
2016 IEEE Applied Power Electronics Conference and Exposition (APEC)