Abstract
This paper presents a hybrid methodology to analyze the commercial measures of changing stator windings and adjusting air gap length to upgrade efficiency of typical three-phase direct-on-line induction motors with die-cast copper rotor (DCR). The calculation is carried out through combining the time-stepping and time-harmonic finite element analysis (FEA) and the circuit equivalent circuit model. Typical full-load performance of stator windings with different air gap lengths are computed by MATLAB invoking the 2D transient and eddy current field analysis in ANSYS/MAXWELL. Then, MATLAB scripts about post-processing of the FEA results are used to obtain the full-load running performance including the loss distribution and circulating current. The MATLAB scripts of circuit model built based on the FEA results is used to compare the overload and starting performance. After that, four stators with the four windings and three DCRs with different air gap of an 11 kW motor are fabricated and tested to validate the calculations. By comparing results from both calculations and measurements, it is shown that the factors of stator windings and air gap length can effectively improve the efficiency of the 11 kW DCR induction motor without the addition of extra materials. The motor with the 11/12 pitch Y-Δ series winding and 0.6 mm air gap has the best performance, in terms of efficiency, overloading capability and starting performance. Its efficiency can increase from 90% to the highest 92.35% by sole adjustment of stator winding and air gap length.
Highlights
Energy issues have caused motor designers, manufacturers and users to pay more attention to efficiency when applying electric motors to production and daily life, as they consume roughly two-thirds of all the electrical energy used by industrial or commercial applications in industrialized countries [1]
Another measure of upgrading materials such as premium electrical grade lamination steel is used for decreasing core losses and Ohmic losses [6,7,8]
The aim of this paper is to develop a hybrid methodology to analyze the influence of commercial measures to comprehensively increase the efficiency of induction motors on full-load, performance
Summary
Energy issues have caused motor designers, manufacturers and users to pay more attention to efficiency when applying electric motors to production and daily life, as they consume roughly two-thirds of all the electrical energy used by industrial or commercial applications in industrialized countries [1]. The higher efficiency can usually be achieved by increasing the active materials, such as increasing the stack length [5,6], in induction motors Another measure of upgrading materials such as premium electrical grade lamination steel is used for decreasing core losses and Ohmic losses [6,7,8]. The efficiency can be improved by enhancing the performance of cooling and bearing systems to reduce the mechanical losses [7] and improving cooling performance to make Ohmic losses less significant [9]. These methods either rise the raw material cost or increase manufacturing complexity
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