An Improved Stray Capacitance Model for Inductors

Abstract

This paper proposes an improved analytical stray capacitance model for inductors. It considers the capacitances between the winding and the central limb, side limb, and yoke of the core. The latter two account for a significant proportion of the total capacitance with the increase of the core window utilization factor. The potential of the floating core/shield is derived analytically, which enables the model to apply not only for the grounded core/shield, but also for the floating core/shield cases. Based on the improved model, an analytical optimization method for the stray capacitance in inductors is proposed. Moreover, a global Pareto optimization is carried out to identify the trade-offs between the stray capacitance and ac resistance in the winding design. Finally, the analysis and design are verified by finite element method (FEM) simulations and experimental results on a 100 kHz dual active bridge (DAB) converter.

A Novel Analytic Method to Calculate the Equivalent Stray Capacitance of the Low-Speed Maglev Train’s Suspension Electromagnet

“…Energies 2020, 13, x FOR PEER REVIEW 2 of 20 [19][20][21]. The measurement methods are black-box techniques, which can help to obtain the equivalent stray capacitance of the suspension electromagnet but have no help to optimize the stray capacitance due to vague physical meaning.…”

“…The SEM winding of the low-speed maglev train is manufactured with the rectangular section wire, and the standard winding method [9,10] is adopted. The capacitance is defined, which is determined by winding shape, size, space position, and insulation parameters, as the static capacitance (inherent capacitance) [9,21]. Figure 2 shows the winding arrangement method and the composition of static capacitances.…”

“…At present, the methods of extracting the stray capacitance mentioned in the literature are the measurement method [6,15,16], the finite element method (FEM) [17,18], and the analytic 2 of 21 method [19][20][21]. The measurement methods are black-box techniques, which can help to obtain the equivalent stray capacitance of the suspension electromagnet but have no help to optimize the stray capacitance due to vague physical meaning.…”

“…Majid Ezati Mosleh et al proposed an analytic method to calculate a slide-conductive rotor magneto cumulative generator's stray capacitance [20], which neglects the effects of the core potential on the electric field energy storage. Zhan Shen et al [21] systematically took the influence of the iron core potential on the electric field energy into account for the first time, furthermore given several approximate methods to estimate the iron core floating potential. At the same time, Zhan Shen's team gave the equivalent circuit method [21], which is suitable for the case of including a few capacitors, whose calculation error increases with the increase in the number of the winding layers.…”

“…Zhan Shen et al [21] systematically took the influence of the iron core potential on the electric field energy into account for the first time, furthermore given several approximate methods to estimate the iron core floating potential. At the same time, Zhan Shen's team gave the equivalent circuit method [21], which is suitable for the case of including a few capacitors, whose calculation error increases with the increase in the number of the winding layers. This paper derives an analytical formula to calculate the equivalent stray capacitance of the SEM, considering the effect of the iron core on electric field energy storage.…”