Impact of switching frequency and edge rates on common-mode current in MVDC microgrids

Recently, a formalized approach was derived to construct common-mode equivalent circuit models (CEMs) of complex power systems. In this paper, an initial focus is on the validation of the approach using Purdue's reduced-scale naval dc microgrid (PDCM). As part of the validation, techniques to characterize the measured and simulated CM performance in the frequency domain are highlighted. Subsequently, Fourier analysis is used to derive analytical expressions for the CM voltages of the PDCM converters that are valid for arbitrary ramp rates and switching frequency. The CM voltages are then used in tandem within the CEM to consider the impact that wide-bandgap (WBG) devices have on the CM behavior of the testbed.