A Terminal Capacitance Method for Analyzing Global Capacitive Effects of Magnetic Components

Periodic switching processes of transistors may cause high-level electromagnetic interference (EMI), which will conduct along magnetic components in the system and threaten electromagnetically sensitive facilities. In order to evaluate impacts of magnetic components on propagation of the EMI, it is necessary to investigate capacitive effects on the whole component, i.e., the global capacitive effects. In this case, detailed partial capacitance (PC) networks based on turn-to-turn and turn-to-ground capacitances may be impractical due to their size and the resultant computational burden. A terminal capacitance (TC) method characterized by explicit physical mechanism and high computation efficiency is proposed to analyze global capacitive effects of magnetic components. By defining coefficient matrix accounting for potential distribution of each winding, PCs corresponding to turns are decoupled to TCs corresponding to external terminals, and quantificational links between TCs and PCs are established with rigorous equations. Furthermore, TCs are directly deduced based on energy computation without having to compute PCs beforehand, making the TC method convenient and efficient. An air-core inductor and a two-winding transformer are used to verify the proposed TC method, and a smoothing reactor employed in the practical UHVdc engineering is used as an application of the method.