Analysis of Space Harmonics in Shaded Pole Induction Motor By Discrete Hartley Transform
Shaded pole induction motors(SPIM) are special type one-phase motors with salient poles. Due to theirs advantages such as simple construction, low cost and easy manufacturing SPIMs are used extensively in ventilation systems, household appliances, etc. Nevertheless, the formation of an elliptical rotating magnetic field in SPIM makes it difficult to analyze these machines. Variable air-gap structure causes the space harmonics which significantly complicates the theoretical analysis of these machines. In this study, the stator-rotor mutual inductance of a 15W 4-pole SPIM is obtained with high accuracy. sensitively. The obtained waveform is subjected to harmonic analysis using Discrete Hartley Transform(DHT). As a result of the analyzes, the third harmonic is obtained as the dominant harmonic (21.76%). 5th, 7th, 9th, 11th and 13th harmonics are varying between 1.15 % to 9.07. Total harmonic distortion (THD) has been calculated as 23.78%. Because of the stator-rotor mutual inductance waveform is symmetrical with respect to rotor position the double harmonics are absent.
Index Terms—Discrete Hartley Transform, Shaded pole motor, Space harmonic, Total harmonic distortion.