Electromotive Force Calculation of Fifteen-phase Induction Motors With Non-sinusoidal Supply

If the positive amplitude point of fundamental magnetic motive force(MMF) is not located identically with the negative amplitude point of 3-order harmonic MMF,the superimposed MMF waveform is named the normal MMF waveform.In this case,the induction electromotive forces(EMFs) are calculated as the precondition for electromagnetic performance analysis and optimization design of the fifteen-phase induction motor with non-sinusoidal supply.Being different from the sinusoidal MMF or the ideal superimposed MMF,the normal MMF leads to the fact that phasor differences between exciting currents and corresponding induction EMFs are not ??/2 due to the saturated magnetic circuits,therefore,the new approach which treats EMFs as exciting current controlled voltage sources is proposed.In view of diversity of air-gap magnetic flux density under each half-pole region of the induction motor,the extended distributed magnetic circuit method based on one-pole region is proposed to calculate air-gap magnetic flux density,by which the fundamental induction EMF and 3-order harmonic induction EMF are obtained.With comparison of the measured fundamental EMF and 3-order harmonic EMF,respectively,with the calculated ones,good agreement between calculated values and measured values shows the validity and accuracy of the extended distributed magnetic circuit method.