An accurate method for modeling transformer winding capacitances

A simple method of modeling parasitic transformer capacitances is presented. This method allows determination of quantitative values for various transformer parasitic capacitances, allows the utilization of a transformer model for circuit analysis that takes the parasitic effects into account, provides a means of critically judging the merits of various winding configurations, and allows the designer to determine whether a given circuit configuration will increase or minimize the effect of transformer parasitic capacity. Voltage and energy relationships are described for uniform field discrete capacitors. Terms that provide a precise way of characterizing these relationships are defined, and examples are given. Nonuniform field capacitive energy storage as found in layer-wound or toroid structures is investigated. With these relationships established, the modeling methodology is presented by a series of examples. It is shown that what appear to be small changes in circuit configuration can result in enormous changes in transformer parasitic effects