A. O. Smith Water Products Company

About: A. O. Smith Water Products Company is a based out in . It is known for research contribution in the topics: Rotor (electric) & Stator. The organization has 414 authors who have published 476 publications receiving 7104 citations.

Computation of Core Losses in Electrical Machines Using Improved Models for Laminated Steel

Abstract: Two new models for specific power losses in cold-rolled motor lamination steel are described together with procedures for coefficient identification from standard multifrequency Epstein or single sheet tests. The eddy-current and hysteresis loss coefficients of the improved models are dependent on induction (flux density) and/or frequency, and the errors are substantially lower than those of conventional models over a very wide range of sinusoidal excitation, from 20 Hz to 2 kHz and from 0.05 up to 2 T. The model that considers the coefficients to be variable, with the exception of the hysteresis loss power coefficient that has a constant value of 2, is superior in terms of applicability and phenomenological support. Also included are a comparative study of the material models on three samples of typical steel, mathematical formulations for the extension from the frequency to the time domain, and examples of validation from electrical machine studies.

On the variation with flux and frequency of the core loss coefficients in electrical machines

Abstract: A model of core losses, in which the hysteresis coefficients are variable with the frequency and induction (flux density) and the eddy-current and excess loss coefficients are variable only with the induction, is proposed. A procedure for identifying the model coefficients from multifrequency Epstein tests is described, and examples are provided for three typical grades of non-grain-oriented laminated steel suitable for electric motor manufacturing. Over a wide range of frequencies between 20-400 Hz and inductions from 0.05 to 2 T, the new model yielded much lower errors for the specific core losses than conventional models. The applicability of the model for electric machine analysis is also discussed, and examples from an interior permanent-magnet and an induction motor are included.

Magnetic Equivalent Circuit Modeling of Induction Motors

Abstract: Finite element models are invaluable for determining expected machine performance. However, finite element analysis can be computationally intense; particularly if a large numbers of studies or high bandwidth studies are required. One method to avoid this difficulty is to extract machine parameters from the finite element model and use the parameters in lumped parameter models. While often useful, such an approach does not represent space harmonics or asymmetries in the motor. A methodology for constructing a state-variable model, based on a magnetic equivalent circuit of the motor is described herein. In addition, the parameters for this model are based solely on geometrical data. This approach is an excellent compromise between the speed of lumped parameter models and the ability of finite element methods to capture spatial effects. Experimental validation of the model is provided.

Interior permanent magnet motor including rotor with flux barriers

Abstract: An electric machine includes a stator, and a rotor positioned adjacent the stator and configured to rotate with respect to the stator. The rotor includes a plurality of laminations having an outside diameter and stacked in a stackwise direction. Each lamination includes a plurality of non-linear slots positioned inward of the outside diameter. Each non-linear slot includes an inner portion spaced a first distance from the outside diameter and two end portions disposed a second distance from the outside diameter. The second distance is smaller than the first distance. The rotor also includes a plurality of permanent magnets. Each magnet is disposed in one of the non-linear slots.

A General Model to Predict the Iron Losses in PWM Inverter-Fed Induction Motors

Abstract: This paper presents an accurate and efficient method for predicting the iron losses in pulsewidth modulation (PWM) inverter-fed induction motors. The method was initially proposed for the prediction of iron losses in a nonoriented soft magnetic material with the same supply conditions. The proposed method requires the separation of the iron losses in the hysteresis and eddy-current components and the average rectified and rms of the PWM voltage values. Starting from the iron losses measured with a sinusoidal supply and the PWM waveform characteristics, a fast and reliable prediction of the iron losses in the motor with the new voltage supply can be obtained. The proposed method has been proved on an induction-motor prototype capable of providing good accuracy in the iron-loss measurement. The comparison between the measured and predicted iron losses with the PWM supply has shown excellent agreement, confirming the validity of the method.