Thévenin Equivalent Circuits for Modeling Common-Mode Behavior in Power Electronic Systems

Abstract

Modeling the common-mode behavior of power electronic systems can be a challenge. This research aims to simplify the process by developing a modeling approach based on Thévenin common-mode equivalent circuits. The Thévenin common-mode equivalent circuits prove to be both straightforward to construct and reliable in predicting worst-case common-mode behavior. In this paper, a theoretical understanding of the Thévenin-based modeling approach is first provided. Subsequently, methods to characterize the Thévenin parameters are established. The modeling approach is then validated experimentally on a dc micro-grid. INDEX TERMS Electromagnetic interference (EMI), leakage current, common-mode (CM), Thevenin equivalent circuit, micro-grid.

Thévenin Equivalent Circuits for Modeling Coupled Common/Differential-Mode Behavior in Power Electronic Systems

“…An LTI TCD-MEC is illustrated in Fig. 2 In general an LTI TCDMEC may not exist for a converter [19]. This is due to the fact that PE converters are fundamentally time-varying circuits resulting from the on/off switching of the transistors/diodes.…”

“…where each ∆S is the error between measured and calculated PSDs (e.g., ∆S 11 = S 11,meas − S 11,calc ). In (19), x is given by…”

“…Recently, in [19], the approaches to model periodically linear time-varying (PLTV) circuits proposed in [20], [21] were used to derive Thévenin CM equivalent circuits of power converters that account for the time-varying nature. Subsequently, the resulting structure of the models was used to justify cases in which time-invariant forms could be applied.…”

“…Subsequently, the resulting structure of the models was used to justify cases in which time-invariant forms could be applied. Herein, the results of [19] are extended to consider converters in which there is coupling between the CM and the DM. Unlike the models in [14]- [18], which assume an LTI form and do not explicitly separate the common-and differential-modes of operation, here PLTV analysis is used to create models that directly account for CM/DM coupling and the time-varying nature of the respective circuits.…”

Modeling of Conducted Emissions for EMI Analysis of Power Converters: State-of-the-Art Review

“…For common-mode current prediction, un-terminated behavioral modeling has been applied to address the aforementioned limitations [21]- [24]. This method is capable of predicting CM emission for changes in the load side.…”