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

Abstract

The single-phase induction motors (SPIMs) are widely used in several household and industrial applications and thus millions of them are produced every year. Despite the fact that their output power is low, their efficiency enhancement could lead to significant energy savings. The SPIMs are included to the new industrial efficiency standards for commercial motors. Consequently, the minimum efficiency that the SPIMs have to present is that of IE3 (premium-efficiency). The already conducted research efforts have not provided a robust and acceptable-from economical and manufacturing point of view-design procedure toward their efficiency improvement. For this purpose, a novel design methodology is proposed here. It is proven that the required efficiency ratings are achievable with the increment of the motor's axial length, the proper design of the rotor bar slot and the careful selection of the auxiliary to main winding turns ratio along with the value of the used capacitor. Aiming to verify its effectiveness, the presented methodology has been applied to SPIMs with different output power ratings. Moreover, the derived results are compared to the corresponding ones obtained from other design strategies. The motor's nominal performance and its behavior during the start-up phase have been determined through finite element analysis.

Effect of Rotor Bars Shape on the Single-Phase Induction Motors Performance: An Analysis toward Their Efficiency Improvement

“…However, the investigations that were conducted in [28] refer to capacitor-run SPIMs that have a squirrel-cage rotor with semi-closed slots of trapezoidal cross-section. The specific rotor bar geometry is commonly preferred by IM designers and manufacturers.…”

“…Aiming to fill this gap, eight different rotor bar shapes (i.e., trapezoidal, oval, pent, polygonical, round, drop, rectangular, and quadrangular) are examined here for a four-pole/1.0 HP capacitor-run SPIM. The calculation of the machine's basic dimensions and the rest of the geometrical parameters is conducted by applying the design methodology that was presented in [28]. The effect of the bar's shape on the motor's efficiency and power factor is highlighted with the help of a sensitivity analysis, which involves the simultaneous variation of (i) the bar's cross-sectional area, (ii) the run-capacitor value, and (iii) the auxiliary to main winding turns ratio.…”

“…In addition, directions that could be valuable for designers and manufacturers toward the SPIMs' efficiency enhancement are given. Last but not least, the generalization of the design approach (proposed in [28] by the authors) is evaluated.…”

“…In particular, a structure with 24 stator slots has been preferred, since the efficiency and power factor of the SPIMs with the certain stator slots number (Q s ) were found to be higher than the respective ones of the machines with Q s = 12 and Q s = 36 for given rotor bars number (Q r ). The SPIM's basic dimensions, airgap length, rotor diameters, as well as its stator slots, rotor bars, and end-ring geometrical characteristics have been calculated as described in [28]. Readers can refer to [28,29] in order to find more information about the electromagnetic features and other quantities (i.e., coefficients, factors, constants, etc.)…”

“…In this way, it will be much easier for them to design and construct new motors with higher efficiency at reasonable turn-around time [26,27]. A complete design methodology, which has been proven to be effective for a variety of capacitor-run SPIMs with different output power ratings and requirements, was presented in [28], which is an author's previous research work. The preliminary findings of [29] were also exploited in that work.…”