Predicting iron losses in soft magnetic materials with arbitrary voltage supply: an engineering approach
TL;DR: In this article, the authors proposed a new approach for predicting iron losses in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with a sinusoidal or pulsewidth modulation supply.
Abstract: We propose a new approach for predicting iron losses in soft magnetic materials with any voltage supply, starting from the knowledge of the iron losses with a sinusoidal or pulsewidth modulation supply. The model is based on the separation of the loss contributions due to hysteresis, eddy currents, and excess losses with the two supplies. Since any contribution depends on the voltage supply characteristics, it is possible to find a direct mathematical relationship between the iron loss contribution and the voltage supply characteristics. As a consequence, an iron loss prediction can be obtained with any voltage supply if it does not produce a hysteresis minor loop. The energetic model is based on coefficients that depend on the magnetic material characteristic. We performed an accurate analysis of the model on eight magnetic materials used for electrical machine construction, of different thicknesses and alloy compositions. In this way, we found the main coefficients for a large spread of magnetic materials. As a consequence, our approach can be a useful support for electrical machine designers when the energetic performance of a magnetic material has to be predicted for a voltage supply different from the sinusoidal one.
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11 Dec 2006
TL;DR: In this paper, 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, and 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.
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.
249 citations
TL;DR: In this paper, 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 were variable only with the induction, is proposed.
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.
239 citations
Cites background from "Predicting iron losses in soft magn..."
...Also included are two example studies from a prototype interior permanent-magnet (IPM) machine and an induction motor....
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TL;DR: It is demonstrated the necessity to consider the harmonics initial phase in order to increase the accuracy in the iron loss prediction in pulse width modulation inverter fed induction motors.
Abstract: This paper intends to develop a more accurate approach for determining the no-load iron losses in pulse width modulation (PWM) inverter fed induction motors. The proposed method is validated by means of a prototype motor with a plastic rotor cage. The iron losses have been computed by the time-stepping finite element method, both with sinusoidal and PWM supply. The iron losses have then been estimated by adding up the contribution generated by orthogonal components of the flux density, as if the iron losses generated by these components were independent phenomena. The rotational hysteresis losses, as well as excess ones, have been calculated applying a correction factor based on experimental data. These factors are a function of the peak flux density and ellipticity of the B vector loci. Experimental validations are provided for several frequency and magnetic saturation values. In addition, this paper demonstrates the necessity to consider the harmonics initial phase in order to increase the accuracy in the iron loss prediction.
135 citations
TL;DR: In this article, a multiphysic modeling of an interior permanent-magnet synchronous machine (IPMSM) dedicated to high speed, including magnetic, electric, thermal, and mechanical aspects, is proposed.
Abstract: High-speed electric drive design is concerned with paying particular attention to thermal and mechanical design of the machine. Therefore, this paper proposes a multiphysic modeling of an interior permanent-magnet synchronous machine (IPMSM) dedicated to high speed, including magnetic, electric, thermal, and mechanical aspects. The proposed analytical models are verified using finite-element (FE) computations. These models are then subjected to a multiobjective optimization-based on genetic algorithm-to design an IPMSM for a high-speed compressor application that develops 30 kW at 20 000 r/min. The design is formulated as a constrained optimization problem consisting of maximizing the machine efficiency while minimizing its weight. The result of this process is a Pareto front between efficiency and weight of the machine allowing the designer to make a posteriori choice. A particular optimal machine is chosen and its performances are validated with FE analysis. This study carries out an optimal multiphysic and multiobjective design approach that allows rationalization of the design process in a realistic computation time thanks to the analytical models involved.
117 citations
Cites methods from "Predicting iron losses in soft magn..."
...[20]—for a given frequency and expressed in watts per kilogram—is employed....
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TL;DR: In this paper, an accurate and efficient method for predicting the iron losses in pulsewidth modulation (PWM) inverter-fed induction motors is presented. But the method requires the separation of the IR losses in the hysteresis and eddy-current components and the average rectified and rms of the PWM voltage values.
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.
111 citations
Cites background or result from "Predicting iron losses in soft magn..."
...The percentage of the two loss components is dependent on the flux density [14], [17]....
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...Previously obtained results [14], [17], [22] demonstrate that the eddy-current loss coefficient ke increases with the induction level and decreases with the frequency....
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References
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TL;DR: In this article, the basic physical mechanism responsible for the general behavior of eddy current losses versus magnetizing frequency fm is recognized in the competition between the external field and local internal fields, due to magnetostatic, coercive, and eddy currents effects.
Abstract: The basic physical mechanism responsible for the general behavior of eddy current losses versus magnetizing frequency fm is recognized in the competition between the external field and local internal fields, due to magnetostatic, coercive, and eddy current effects. The concept of magnetic object, corresponding to a group of neighboring walls evolving in a highly correlated fashion, is introduced in order to take into proper account the role of short‐range internal correlation fields. With a random spatial distribution of magnetic objects, the dynamic loss is essentially a function of the number n of magnetic objects which are simultaneously active at each value of fm. It is shown that the dynamic balance between applied field and local eddy current counterfields leads, with increasing fm, to a progressive increase of n governed by the simple linear law n=n0+Hexc/V0, where Hexc represents the part of the applied field in excess of the hysteresis and classical contributions. Under these conditions, a general law of losses is derived, which turns out to be in excellent agreement with several experimental results concerning different iron‐based ferromagnetic alloys. On the basis of the general validity of the obtained loss equation, a bidimensional map of dynamic losses is defined and constructed, in which the parameters n0 and V0 are used as orthogonal coordinates of representative points characterizing the loss behavior of different materials. This map provides the proper basis for a general classification of dynamic losses, which might also be useful from the applicative point of view.
252 citations
TL;DR: In this paper, a simple and efficient method for the estimation of iron loss under any nonsinusoidal voltage without multiple zero crossings (i.e. without minor hysteresis loops) is proposed.
Abstract: A simple and efficient method for the estimation of iron loss under any nonsinusoidal voltage without multiple zero crossings (i.e. without minor hysteresis loops) is proposed. This method is based on the loss separation model, where iron loss is decomposed into hysteresis, classical and excess loss components. The voltage waveform is identified by the form factor coefficient, easily accessible. Knowledge of the voltage harmonic spectrum is not required in this method. The cases of rectangular pulse, PWM, and fundamental plus a controlled third harmonic voltage are treated and a satisfactory prediction of iron loss is obtained. >
111 citations
TL;DR: In this article, a systematic PWM iron loss study has been carried out and all the loss components can be given as functions of the sum of pulses width in half a period.
Abstract: A systematic PWM iron loss study has been carried out. All the loss components can be given as functions of the sum of pulses width in half a period. PWM loss surplus when compared with the sinusoidal supply is more pronounced in the laminations with more important part of dynamic loss in the whole loss outcome. Along the constant flux trajectories in variable speed regimes of the induction machines the iron losses are also constant. The underlying analysis has been developed for an alternative magnetic field and tested on an Epstein frame. However, the iron loss invariability (per cycle) on the constant flux trajectories has been confirmed in motor measurements, where the actual field is far more complicated.
70 citations
"Predicting iron losses in soft magn..." refers background in this paper
...Different approaches have been proposed by the researchers but, unfortunately, they are quite complex, and the obtained results cannot be considered suitable for an immediate use by electrical machine designers [ 1 ]‐[4]....
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17 Jun 2001
TL;DR: In this paper, a method to determine the effects due to the punching process on soft magnetic materials used in the electrical machines has been presented, based on a full experimental approach, where four wound cores, having the same geometrical dimensions have been assembled as the overlap of a different number of rings.
Abstract: The paper presents a method to determine the effects due to the punching process on soft magnetic materials used in the electrical machines. The proposed methodology, is based on a full experimental approach. Four wound cores, having the same geometrical dimensions, have been assembled as the overlap of a different number of rings. The rings have been obtained by means of a punching process and in this way the four wound cores present an evident difference in terms of punched edge length. The comparison between the magnetic and energetic properties on the four cores has put in evidence in a qualitative and quantitative way, the punching process effects.
30 citations
"Predicting iron losses in soft magn..." refers background in this paper
...These effects have been analyzed by the authors in [7], [ 8 ], where the deterioration of the magnetic characteristics have been taken into account....
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03 Oct 1999
TL;DR: The obtained building factor has been used to predict the iron losses in the stator core of an induction motor realized with the same magnetic material used for the wound cores.
Abstract: In the paper a possibility to determine the iron losses building factor is proposed. The used methodology, which has to be intended as a first approach to the problem, is based on a full experimental approach. Four wound cores, having the same geometrical dimensions, have been assembled as the addition of different number of rings of the same magnetic material. The rings have been obtained by means of a punching process and as a consequence, the four wound cores present a well evident difference in terms of punched edges perimeters. The comparison between the specific losses [W/kg] has been used to obtain the iron loss increase due to the punching process. A building factor defined as the iron loss increase for punched edges length and for sheet can be obtained. The obtained building factor has been used to predict the iron losses in the stator core of an induction motor realized with the same magnetic material used for the wound cores. The comparison between the measured and the predicted results is quite good and it can be considered an interesting starting point for future research.
29 citations