Identification of stator insulation material partial discharge parameters during lifetime

With the increasing importance of wide bandgap material like silicon carbide (SiC) used in inverters, mainly due to the fast switching transitions and increased frequencies, the challenge for conventional electrical machines regarding insulation material stress is significantly increased. Therefore, the detection of partial discharge (PD) is a very important factor. It has recently been shown, that PDs not only occur on the rising edge, but also in the flat area of voltage pulses. Thus accurate detection of PD events is of major importance to characterize changes in PD properties due to voltage stress over lifetime. In a special test arrangement PD can be identified by sudden and short voltage drops what also allows for an estimation of the energy involved with the PD.