Middle Frequency Transformer Investigation for Solid-State Transformer

This paper investigates the middle frequency transformer for the solid-state transformer. It is expected to be used in the traffic and power system. One of the key technologies is the solid-state transformer. The 3kHz, 5kVA transformers with some different core materials are manufactured. Dependency of the loss in the transformer to frequency is investigated. Estimated equation from the Steinmetz equation and some results are shown. Copper loss is also considered by using the measured resistance at various frequencies. It is indicated that the copper loss is major in the medium frequency transformer.