Analysis of features of magnetic field of a synchronous electric machine with a multi-phase fractional slot winding in a polyharmonic mode of operation

Abstract

An analytical model has been developed for calculating magnetic field in a multiphase synchronous electric machine with fractional toothed windings. For this, a harmonic analysis of the distribution functions of the magnetic field of excitation and the magnetic field of the armature reaction was carried out, taking into account the presence of higher harmonic components in the function of the magnetomotive force of permanent magnets, variable magnetic conductivity of the air gap, polyharmonic mode of operation of a multiphase electric machine and a non-sinusoidal law of variation of spatial winding functions. As a result of the analysis, the substantiation is given that in the investigated electric machine a nine-phase winding can extract with the greatest efficiency the harmonic components of the first and third order of a rotating magnetic field to create flux linkage and induce an electromotive force (as well as create a magnetomotive force with prevailing spatial harmonics of the first and third order). In the investigated electric machine, the amplitudes of the working harmonics of the induction of the modulated magnetic field of the armature reaction can be increased due to the modulation of the inoperative harmonics of the magnetomotive force of the armature response by the stator teeth to the first and third order. To check the developed provisions, a magnetostatic vector model of the magnetic field of the investigated electric machine was created. The simulation results confirmed the high efficiency of the developed analytical model for calculating the magnetic field in a synchronous electric machine with fractional toothed windings. The use of such a model will make it possible to reveal most reliably the influence of the geometricparameters of the magnetic circuit and the multiphase winding circuit on the nature of the change in the functions of the magnetic field in the air gap with the lowest time costs in the process of optimizing an electric machine.