Methods For Reduced Computation Time For Frequency-Domain Evaluation Of Transient Voltage Effects In Electric Machines

Due to increasing slew rates when using wide bandgap semiconductors in inverters, such as SiC and GaN, very high voltage transients occur in electrical machines. This further causes severe voltage stress on the isolation system and possibly partial discharge or electromagnetic interference issues. Therefore, a high-frequency multi-turn model of an electric machine is created, modeling the influence of steep voltage steps on the stator windings. A state-space model of the electrical network is extracted and evaluated analytically in the frequency domain. The presented approach contributes to the state of the art because it is widely applicable and computationally efficient. To further reduce computation time analytical methods for evaluating the parameters of the electrical network are presented. Moreover the combination of parallel wires in the network model is proposed, decreasing the computation effort significantly for machines with high number of parallel branches. Measurements of voltage transients are performed for a 3-phase synchronous machine with a nominal power of 23 kW and compared to the simulation results.