Analytical Methods for Estimating the Equivalent Stray Capacitance of Single-Layer Core Windings

The analytical methods for estimating the equivalent stray capacitance (ESC) in a single-layer iron core winding include the capacitance network method (CNM) and the energy equivalence method (EEM). The CNM is limited to applications in symmetrical windings, and the EEM is restricted to use in multiconductor systems (MCSs) with fully known potential distributions. These methods are improved in this article. The winding symmetry limitation of the CNM is eliminated, and the EEM is used to calculate the ESC of MCSs containing floating potential conductors. ESC calculations are found to differ between the CNM and the EEM. The accuracies of the hypotheses used in the CNM and the EEM and the ESCs calculated with each approach are assessed and compared based on finite-element simulations, circuit simulations and experiments. The results show that at the first resonant frequency condition, the EEM hypothesis is more consistent with reality than that of the CNM, and the ESC calculated with the EEM is more accurate. The ESC errors incurred when using the CNM and the EEM are mainly due to model errors introduced by the discrepancies between the assumptions and the actual conditions.