Revolving-field polygon technique for performance prediction of single-phase induction motors

Abstract

Abstract-This paper presents a new analytical technique for improving the performance prediction of single-phase induction motors, especially capacitor motors. The technique uses the split-phase motor electrical equivalent circuit analysis together with electrical and magnetic parameters whose variation is computed from the equivalent balanced polyphase motor, so that the same magnetic circuit analysis can be used for both. (The term split-phase is used to cover motors operating from a single-phase supply but with the phase windings split into two orthogonal windings, one of which may have a capacitor in series with it during running or starting.) The technique accounts for the elliptical envelope of the magnetizing field vector and results in improved precision, since the three-phase electromagnetic model is considered to be more precise than the normal split-phase motor analysis. An important result is the computation of vector polygons of flux density for each section of the magnetic circuit, providing a better basis for core loss prediction. The double-frequency torque ripple is also obtained from the stator magnetomotive force and flux-density polygons. Three different electrical equivalent circuit methods for the split-phase motor (based respectively on the cross-field theory, forward-and backward-revolving fields, and symmetrical components) are evaluated to determine the method best suited for incorporating the variation of the circuit parameters from the polyphase magnetic circuit analysis, and it is discussed how the core losses can be included in these circuits to obtain the best overall performance prediction.

Comparison of Electromagnetic Characteristics of Single-Phase Induction Motor between Balanced and Unbalanced Operation under Different Loads

“…In balanced-load condition, the stator MMF with respect to the fundamental frequency rotates with the same magnitude at the fundamental frequency, but the fluctuation increases as the operation deviates from balanced condition. Unlike the stator MMF, the trajectory of magnetizing MMF is rather a circular shape, referring to some researches [3]. This is because the reaction field created by rotor MMF, thus the resultant field MMF can be simplified as the term of only forward rotating field, as written as: Unlike the stator MMF, the trajectory of magnetizing MMF is rather a circular shape, referring to some researches [3].…”

“…Unlike the stator MMF, the trajectory of magnetizing MMF is rather a circular shape, referring to some researches [3]. This is because the reaction field created by rotor MMF, thus the resultant field MMF can be simplified as the term of only forward rotating field, as written as: Unlike the stator MMF, the trajectory of magnetizing MMF is rather a circular shape, referring to some researches [3]. This is because the reaction field created by rotor MMF, thus the resultant field MMF can be simplified as the term of only forward rotating field, as written as:…”

“…In addition, impedance of both windings is adjusted by geometrical changes or additional capacitors to split into two-phase sources. Even though decreasing prices of inverter-fed drive have spread to operate two-phase or three-phase motors electronically, but SPIMs still have strong merits for its simplicity and maintenance [1][2][3][4].…”

A novel design methodology for the compliance of single phase induction motors with recent industrial premium efficiency standards

“…However, millions of them are produced every year. Also, research studies have mentioned that the efficiency improvement of the specific motors could lead to significant potential for savings in energy consumption 2 …”

“…In these models, the impact of eddy currents and also non‐linear effects (eg, magnetic saturation on motor's parts) were taken into account 5 . Moreover, improved equivalent circuits based on the cross‐field theory, the forward and backward revolving fields and symmetrical components were proposed in Reference 2 aiming to obtain the best overall motor's performance prediction.…”