An algebraic approach to prediction of the performance of PM electric machines during sustained fault conditions

A computer aided method for predicting the performance of three-phase permanent magnet machines during normal and sustained fault conditions is presented. An approach based on Fourier series signal representations of the machine parameters and waveforms is used to determine the sustained fault currents and voltages. Using a model in the abc reference frame, the unknown but periodic currents and/or voltages are modeled as Fourier series. With the constant velocity assumption, the derivatives of the inductances can be calculated, and derivatives of the currents can be calculated as functions of the unknown current Fourier series coefficients. Thus the model equations become algebraic and hence solvable by algebraic means