Analysis of influence of third spatial harmonic on currents and torque of multi-phase synchronous machine with permanent magnets

摘要

In the case of multi-phase machines and in machines with special winding arrangements, such as combined star-delta winding, the third spatial harmonic of the magnetomotive force can, unlike in three-phase machines, negatively influence the waveforms of stator currents and torque of the machine. The paper shows how permanent magnets give rise to the third spatial harmonic of the magnetic flux in the air gap and how this harmonic influences the currents and the torque. The analysis of the situation in the machine is carried out by means of the method of space vectors and symmetrical components of the instantaneous values of currents and voltages. The result of the analysis is a mathematical description of the machine. By means of numerical simulations, it is shown how the third spatial harmonic distorts the waveforms of the stator phase currents and torque.