Transformer design for reducing the inrush current by asymmetrical winding

This study proposes a novel approach for designing transformers to reduce the inrush current using asymmetrical winding. Differently from traditional methods, the inrush current was reduced based on increasing the inrush equivalent inductance by changing the proportion of inner layer to outer layer in coil winding. To estimate the distributive ratio of winding, the formulae of the inrush equivalent inductance and the leakage inductance are calculated from the structural parameters of the transformer. By theoretical analyses, an optimum distributive ratio of coil winding is presented. Experimental results confirm that inrush current can be reduced concurrently with appropriate voltage regulation and short-circuit current in transformer.