Evaluation of the Impact of Switching Speed on Inductors in SiC Converters

Inhalt:
The implementation of the Silicon Carbide (SiC) semiconductor device enables higher switching frequency and higher switching speed in power electronic converters. While the high switching speed (dv/dt) effect of SiC devices is relatively well understood at the power device level, limited research has been conducted to reveal its impact on the magnetic components (e.g. inductors) in a power converter. This work carries out an experimental evaluation of the switching speed impact with respect to the magnetic core loss and parasitic capacitance of a filter inductor. A Triple Pulse Test procedure is applied to the inductor to provide high-voltage, large-signal excitement, with two testing variables considered, i.e. frequency and flux density swing. Core loss under various switching speed settings and dc-bias levels have been tested and compared. The results show the changes in core loss are not strongly related to the variation of the switching speed. An abnormal current distortion caused by the inductor parasitic capacitance has been observed under the high switching speed. An equivalent model and verification regarding the capacitance properties are provided. The effect of parasitic capacitance on core loss under different switching speeds is also evaluated.