Saturation Harmonics and Current Waveforms of Single-Phase Induction Motors

The harmonics in the air gap magnetic field of saturated single-phase induction motors with uniform or nonuniform stator teeth and cores are analyzed using two-dimensional Fourier series. The analysis shows that when the fundamental backward-traveling and forward-traveling magnetic field waves are saturated they produce saturation harmonics having several different velocities, frequencies, and spatial harmonics. The saturation harmonics for an applied 60 Hz voltage can include 180 Hz and 300 Hz waves with spatial harmonics equal to the number of pole pairs, which create 180 Hz and 300 Hz components in the current drawn by the motor. Current waveforms are shown which demonstrate the saturation effects.