Evaluation of space harmonics in a “C” type shaded pole motor and sensitivity study of its stalled torque with respect to its design parameters

A three-dimensional nonlinear transient analysis is used to demonstrate the complexity and importance of the space harmonics in “C” frame shaded pole motors. The trajectory (locus) of the fundamental and space harmonics of the air-gap magnetic flux distribution for the first fifteen harmonics were calculated. The significance of space harmonics is demonstrated by plotting their THD (total harmonic distortion), DF (distortion factor), DF_n (distortion factor of an individual harmonic), and HF_n (harmonic factor of an individual harmonic) as a function of time. Other hard to measure quantities such as induced current in the shading rings are also obtained from the results of the analysis. Equivalent forward and backward revolving magnetomotive forces (MMFs) were calculated from the simulation results. By design parameter changes, the sensitivity of the stalled torque were calculated. The commercially available MSC/EMAS finite element package was used in this study