Using Transformer Parasitics for Resonant Converters—A Review of the Calculation of the Stray Capacitance of Transformers

Parasitic capacitances of conventional transformers can be used as resonant elements in resonant DC-DC converters in order to reduce the overall system size. For predicting the values of the parasitic capacitors without building the transformer different approaches for calculating these capacitances are compared. A systematic summary of the known approaches is given and missing links between the different theories and missing equations are added. Furthermore, a new simple procedure for modeling parasitic capacitances that is based on the known approaches is proposed. The resulting equations are verified by measurements on four different high voltage transformers.