On the Effect of Disorder on Stray Capacitance of Transformer Winding in High-Voltage Power Supplies

Stray capacitance of transformer winding is an important parasitic element influencing the behavior of the switching power converters, especially for high-voltage transformers. There are various methods for calculating the stray capacitance in transformers and inductors with ordered windings. However, an ordered winding is less likely with an increased number of turns and layers. In this paper, it is shown that a slight disorderliness in winding leads to a considerable difference between the value of winding stray capacitance of the former ordered winding and its slightly disordered scheme. Therefore, regular methods for calculating the stray capacitance have significant errors in a disordered winding. A generic method is proposed to calculate the stray capacitance of a winding with disordered turns. The proposed method is to apply the probabilistic tools to evaluate the possible position of winding turns and calculation of stray capacitance for all possible winding diagrams. As the number of possible winding diagrams is very large, especially in high turn windings, Kolmogorov-Smirnov theorem is used to estimate the winding stray capacitance based on the reduced number of possible winding diagrams. The energy method is used to calculate the equivalent stray capacitance of winding. Using this calculation method, the effect of disorder and some other parameters on the value of stray capacitance is investigated. The proposed method is tested and validated with the computer simulation and the experimental measurement.