Optimal Design and Implementation of High-Voltage High-Power Silicon Steel Core Medium-Frequency Transformer

A 1.5 kV, 35 kW, 1 kHz silicon steel core medium-frequency transformer is designed and prototyped for a 10 kV, 0.5 MW electronic power transformer. This transformer uses 0.18 mm silicon steel as core material due to the advantages of easy processing, high saturation flux density, low noise, and low cost. The detailed design considerations and an optimal design method are presented in this paper. Different from the previous work on medium-frequency transformer design, the proposed approach takes ripples into account. Core loss model under square wave excitation with ripple and winding loss model considering sideband harmonics are established. Besides, two-dimensional finite-element simulations are adopted to obtain ac/dc resistance factors. Finally, the proposed approach is verified by experiments on prototype. The test results show performance better than expected, with desirable no-load loss and power density of 2.9623 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> W/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .