A computationally efficient method for calculation of strand eddy current losses in electric machines

Fatemi, Alireza; Ionel, Dan M.; Demerdash, Nabeel A. O.; Staton, D.A.; Wróbel, Rafał; Chong, Yew Chuan

doi:10.1109/ecce.2016.7854667

Cited by 14 publications

(13 citation statements)

References 21 publications

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“…It should be noted that for random windings, methods such as the one described in [2] maybe further developed for 3D application in conjunction with the new techniques described in this paper. Also, it is important to carefully adapt the flux density sampling to the problem.…”

Section: Proposed Methodsmentioning

confidence: 99%

“…A discrete sampling along radial direction with N L samples can be performed in which case the coordinates of the sample points in the general 3D FEA model can be obtained from (2).…”

Section: Proposed Methodsmentioning

confidence: 99%

“…In order to bridge the gap, hybrid methods have been proposed [2], [8], [9]. These methods generally employ the FEA calculated flux density in one coil cross section in order to provide a trade-off between accuracy and computational speed.…”

Section: Introductionmentioning

confidence: 99%

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A Hybrid Analytical and FE-based Method for Calculating AC Eddy Current Winding Losses Taking 3D Effects into Account

Taran

Ionel

2019

2019 IEEE Energy Conversion Congress and Exposition (ECCE)

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This paper proposes a new hybrid analytical and numerical FE-based method for calculating ac eddy current losses in wire windings and demonstrates its applicability for axial flux electric machines. The method takes into account 3D field effects in order to achieve accurate results and yet greatly reduce computational efforts. It is also shown that hybrid methods based on 2D FE models, which require semi-empirical correction factors, may overestimate the eddy current losses. The new 3D FE-based method is advantageous as it employs minimum simplifications and considers the end turns in the eddy current path, the magnetic flux density variation along the effective length of coils, and the field fringing and leakage, which ultimately increases the accuracy of simulations. Case studies of axial flux PM motors: one with concentrated windings and open slots and another one with a coreless topology, are included.

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Section: Proposed Methodsmentioning

confidence: 99%

“…A discrete sampling along radial direction with N L samples can be performed in which case the coordinates of the sample points in the general 3D FEA model can be obtained from (2).…”

Section: Proposed Methodsmentioning

confidence: 99%

See 1 more Smart Citation

A Hybrid Analytical and FE-based Method for Calculating AC Eddy Current Winding Losses Taking 3D Effects into Account

Taran

Ionel

2019

2019 IEEE Energy Conversion Congress and Exposition (ECCE)

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“…It should be noted that is calculated by a strand eddy-current loss model in ref. [26] with the aim to include the skin-effect and strand eddy-current losses due to the presence of slot leakage and fringing fluxes. While and are calculated with the core losses and magnet losses models in ref.…”

Section: B Optimization Fitness Functionmentioning

confidence: 99%

Computationally Efficient Optimization of a Five-Phase Flux-Switching PM Machine Under Different Operating Conditions

Chen

Liu

Demerdash

et al. 2019

IEEE Trans. Veh. Technol.

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This paper investigates the comparative design optimizations of a five-phase outer-rotor flux-switching permanent magnet (FSPM) machine for in-wheel traction applications. To improve the comprehensive performance of the motor, two kinds of large-scale design optimizations under different operating conditions are performed and compared, including the traditional optimization performed at the rated operating point and the optimization targeting the whole driving cycles. Three driving cycles are taken into account, namely, the urban dynamometer driving schedule (UDDS), the highway fuel economy driving schedule (HWFET), and the combined UDDS/HWFET, representing the city, highway, and combined city/highway driving, respectively. Meanwhile, the computationally efficient finite-element analysis (CE-FEA) method, the cyclic representative operating points extraction technique, as well as the response surface methodology (in order to minimize the number of experiments when establishing the inverse machine model), are presented to reduce the computational effort and cost. From the results and discussion, it will be found that the optimization results against different operating conditions exhibit distinct characteristics in terms of geometry, efficiency, and energy loss distributions. For the traditional optimization performed at the rated operating point, the optimal design tends to reduce copper losses but suffer from high core losses; for UDDS, the optimal design tends to minimize both copper losses and PM eddy-current losses in the low-speed region; for HWFET, the optimal design tends to minimize core losses in the high-speed region; for the combined UDDS/HWFET, the optimal design tends to balance/compromise the loss components in both the low-speed and high-speed regions. Furthermore, the advantages of the adopted optimization methodologies versus the traditional procedure are highlighted. SECTION I. Introduction As the most important component in the traction system of electric vehicles (EVs), electric machines should be designed to have high torque density to provide the required acceleration capability in the low-speed region, and high flux-weakening capability to expand the constant-power speed range in the high-speed region. Compared to the conventional machine topologies commonly used in this application, e.g., induction motors [1], switched reluctance motors [2], and permanent magnet synchronous motors (PMSM) [3], flux-switching permanent magnet (FSPM) machines have attracted more attention due to their simple and robust rotor, high torque density, and favorable thermal dissipation [4]. Recently, FSPM machines with various configurations such as original configurations [5], C-and E-core configurations [6], have been presented for a diversity of applications. However, most of these configurations are limited to three-phase inner-rotor machines. Multi-phase motors have shown advantages in terms of their fault-tolerance capability, low torque pulsation, and additional degrees of freedom in the associated control sy...

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“…This is in order to include the portion of the ac losses that stems from the presence of slot leakage and fringing fluxes in the performance characterization of such machines. The developed hybrid analytical-numerical loss calculation method is rendered computationally efficient (CE) through adopting several measures, such as alternative coil modeling, which reduces the computation time required for solving the FE model, exploiting the existing electric symmetry in addition to the magnetic periodicity of PM machines with sinusoidal current excitation, and implementing fast analytical techniques for mapping the flux within the slot area, estimating the fill factor and strand locations, and finally characterization of the eddy current losses based on the value of the flux density impinging on each stator winding conductor [20]. The presented loss calculation method does not account for ac losses that are three-dimensional (3-D) in nature [21]; thus, the effects of twisting and transposition throughout the length of the conductors are not considered, neither does it address the circulating losses appearing in bundled conductors [17], [22], as these losses do not occur at the strand level.…”

Section: Section I Introductionmentioning

confidence: 99%

Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

Fatemi

Ionel

Demerdash

et al. 2019

IEEE Trans. on Ind. Applicat.

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A fast finite element (FE) based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines is presented in this paper. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions that exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor s f for all the design variations, the maximum s f in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. Rather than pursuing the precise estimation of ac conductor losses, the research focus of this paper is placed on the development of a computationally efficient technique for the derivation of strand eddy current losses applicable in design optimization, especially where both the electromagnetic and thermal machine behavior are accounted for. A fractional-slot concentrated winding permanent magnet synchronous machine is used for the purpose of this study due to the higher slot leakage flux and slot opening fringing flux of such machines, which are the major contributors to strand eddy current losses in the windings. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winding loss effects for this machine design, a subject that has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results.

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A computationally efficient method for calculation of strand eddy current losses in electric machines

Cited by 14 publications

References 21 publications

A Hybrid Analytical and FE-based Method for Calculating AC Eddy Current Winding Losses Taking 3D Effects into Account

A Hybrid Analytical and FE-based Method for Calculating AC Eddy Current Winding Losses Taking 3D Effects into Account

Computationally Efficient Optimization of a Five-Phase Flux-Switching PM Machine Under Different Operating Conditions

Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

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