Current Sharing Analysis of a High Power Transformer with Parallel Windings

With the development of electric transportation, resonant converters are widely used. However, the increased power and frequency make it more difficult to design the magnetics. For this application, litz wires with thinner strands and more strand numbers are needed, which is expensive and hard to get. So, parallel windings are usually used to reduce the current stress. In this paper, an analytical model of the current sharing for parallel windings is introduced. According to the model, a perfect current sharing structure is designed so that the transformer can stand a much higher current. A 30 kW 100 kHz Serial Half Bridge DC-DC converter prototype is designed to verify the methods at last.