Analytical Computation for AC Resistance and Reactance of Electric Machine Windings in Ferromagnetic Slots

Xu, Shijie; Ren, Hongliang

doi:10.1109/tec.2018.2843357

Cited by 16 publications

(13 citation statements)

References 26 publications

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“…Where * is the copper conductivity and µ + is the void permeability. The model below, presented in [21], is very accurate under its hypothesis, and is used to predict losses for a real case study, where some hypotheses are not fully respected. The authors in [21] considered the following assumptions: 1) Permeability of iron core is infinite; 2) End effects are neglected; 3) Magnetic field lines are horizontal across the slots; 4) Sinusoidal current is applied to conductors; 5) Conductors are positioned in floors with height equal to the diameter of conductors D as shown in Fig.…”

Section: Conventional Methodsmentioning

confidence: 99%

Experimental Statistical Method Predicting AC Losses on Random Windings and PWM Effect Evaluation

Preci

Valente

Galassini

et al. 2021

IEEE Trans. Energy Convers.

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Nowadays, one of the challenges in transport electrification is the reduction of the components' size and weight in order to improve the power density. This is often achieved by designing electrical machines with higher rotational speeds and excitation frequencies. In addition, the converter needs to control the machine over a wide speed range given by the mission profile. Therefore, copper losses can significantly increase due to the combination of high frequency excitation and the harmonics introduced by the converter .The winding arrangement design plays a key role in the minimization of the copper losses, thus towards a higher efficiency and/or an improved power density. Different winding topologies can be adopted for high speed electrical machines and amongst them random windings are still one of the most widespread types. This paper presents an in depth study on AC losses in random windings for high frequency motor applications. An analytical method is compared against 2-D Finite Element (FE) simulation results. These are then compared to experimental measurements taken on a custom motorette. Importantly, in order to take into account the random positions of each strand within the machine slots, an Experimental Statistic Method (ESM) is proposed. The ESM allows to define the probability distribution which is useful to evaluate the winding copper losses at the design stage. The contribution of the Pulse Width Modulation (PWM) effect is also considered and experimentally evaluated.

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Section: Conventional Methodsmentioning

confidence: 99%

Experimental Statistical Method Predicting AC Losses on Random Windings and PWM Effect Evaluation

Preci

Valente

Galassini

et al. 2021

IEEE Trans. Energy Convers.

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“…For the multilayer rectangular conductors placed in a ferromagnetic slot, from Ampère’s circuital law and Faraday’s law, the effective AC resistance of each conductor in the k th layer can be derived as 21 where h , d , and l are the height, width, and length of the conductors, respectively, σ is the conductivity of the conductors, f is the frequency of the current, μ 0 is the permeability of the vacuum, w s is the width of the slot, n k is the number of the conductors in the k th layer, and Sn k -1 is the sum of all conductors under the k th layer. For a round conductor, it can be equivalent to a square conductor with the same cross-sectional area.…”

Section: Comparison Of Round Wires and Rectangular Wiresmentioning

confidence: 99%

Analysis of a thrust magnetic bearing with rectangular wire winding

Sun

Ren

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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Active magnetic bearings generally use the coils made of enameled round wires, which have a low filling factor and waste plenty of slot space, resulting in large volume and weight of the machine. This paper introduces the rectangular wires to apply in magnetic bearings. The rectangular wires can be wound compactly without gaps and increase the wire filling factor, thereby reducing the size of the magnetic bearing stators, as well as the associated rotor part. These structural improvements are greatly beneficial to the high-speed rotating machinery in the aspects of windage losses, natural frequency, and material strength of the rotor, which are quantitatively analyzed. By utilizing the rectangular wire, a coil for a thrust magnetic bearing prototype is fabricated and tested, demonstrating the practical feasibility of the rectangular wires to apply in magnetic bearings.

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“…Based on existing research work in academia, circulating current issue can be investigated based on finite element method (FEM) [4] [7][8][9][10][11], analytical methods [12][13][14][15][16], and the semi-analytical methods [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…To overcome the disadvantage of long calculation time of FEM, analytical methods [12][13][14][15][16] have been proposed to evaluate AC copper loss. The analytical method obtains the slot leakage field by directly solving the Maxwell's equations in the slot, and ultimately derives the circulating current in the strands through the analytical circuit model [12][13][14] or directly calculates the AC losses based on the Poynting's theorem [15] [16].…”

Section: Introductionmentioning

confidence: 99%

A Computationally Efficient Semi-Analytical Method for Circulating Current Loss of High Speed Permanent Magnet Machines

Li,

Fan,

Liu

et al. 2024

IEEE Trans. Energy Convers.

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This paper proposes a computationally efficient (CE) semi-analytical method for winding power loss calculation of high speed permanent magnet machines induced by circulating current. It combines a CE magnetostatic finite element method (FEM) for rapid slot leakage field extraction and an analytical circuit model for circulating current calculation. Time-space transformation based CE FEM is applied for efficient slot leakage field extraction considering the polyphase windings.Besides, a conductor model with an automatic and practical turn splitting strategy is proposed to consider the effect of conductor positions and bundle shapes on the circulating current loss. The results on circulating current waveforms and corresponding losses show that the proposed method has high accuracy and can significantly reduce the simulation time, with an error less than 2% and the simulation time only 1/400 for the studied machine compared with the commercial FEM. Using the proposed method, the influence of some factors, including the turn number, the transposition effect and the bundle shape on the circulating current loss are investigated. Finally, the proposed method is further verified by experimental measurements implemented on two stator specimens.

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Analytical Computation for AC Resistance and Reactance of Electric Machine Windings in Ferromagnetic Slots

Cited by 16 publications

References 26 publications

Experimental Statistical Method Predicting AC Losses on Random Windings and PWM Effect Evaluation

Experimental Statistical Method Predicting AC Losses on Random Windings and PWM Effect Evaluation

Analysis of a thrust magnetic bearing with rectangular wire winding

A Computationally Efficient Semi-Analytical Method for Circulating Current Loss of High Speed Permanent Magnet Machines

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