Magnetic Losses Evaluation in PM SM Drive with Non Sinusoidal Supply by Finite Elements Analysis and Superposition

Field superposition in rotating machines with sinusoidal distribution of magneto motive force and non sinusoidal voltage supply is analyzed in view of specific behavior of field components rotating in opposite direction at the same velocity in relation to rotor. These components -5th and 7th, or 11th and 13th etc -form oscillating fields which imply rotor losses quite different than it is usually expected in superposition procedures, where overall losses are given by sum of effects produced by individual harmonic components of sliding fields. In case of eddy current losses in rotor's permanent magnets the difference for one pair of harmonics can reach several tens percent.