Efficient Frequency-domain Evaluation of Transient Voltage Effects in Electric Machines

The use of wide bandgap semiconductors in inverters such as SiC and GaN can lead to very high volt-age transients in electric machines, causing severe voltage stress on the isolation system and possibly electromagnetic compatibility (EMC) issues. In order to model the influence of steep voltage steps on stator windings a high-frequency multi-turn model of an electric machine is created. The parameters for the electrical network including their fre-quency dependency are determined analytically or via 2D finite elemente method (FEM). Furthermore, a state-space model of the electrical network is extracted. Since the model is evaluated analytically in the frequency domain, this method is computationally efficient and more flexible than conventional approaches that use network analysis software such as SPICE. First measurements of transient voltage effects are performed for a 3-phase 23 kW permanent magnet synchronous machine supplied by an inverter with 276 V DC-link voltage at 12 kHz, validating the proposed simulation method.