Power Loss Analysis and Optimal Design of High Efficiency MW-level Medium Frequency Transformer

High efficiency MW-level medium frequency transformer is the core basic equipment to realize large-scale new energy collection and transmission. The large capacity and medium frequency characteristics of transformer make the working condition of the iron core, winding and cooling system change, and the loss of transformer increases, which becomes the bottleneck restricting its wide application. In order to reduce the loss, the loss characteristics of the MW-level medium frequency transformer are analyzed in this paper. At the same time, based on the loss characteristics, this paper presents the corresponding material selection and structural improvement of the loss optimization method for the core, winding and cooling system. Finally, based on the proposed loss optimization methods, a 1.5 MVA/600 Hz medium frequency transformer was optimized in design, and the prototype development, efficiency, and temperature rise tests were completed. The efficiency of the transformer under rated working conditions reaches 99.57% and the temperature rise is lower than 60K, which verifies the effectiveness of the proposed loss optimization method.