Investigation of Resistivity Impact on AC Losses in Hairpin Conductors

Pastura, Marco; Barater, Davide; Nuzzo, Stefano; Franceschini, Giovanni

doi:10.1109/iecon48115.2021.9589047

Cited by 13 publications

(7 citation statements)

References 21 publications

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“…The use of hairpin windings could be beneficial in terms of weight reduction; nevertheless, the AC losses (which are a big source of losses in superconducting machines due to the higher magnetic flux densities in the slot area) in hairpin windings are significantly higher than in other technologies [45]. The skewed winding is characterised by the introduction of the coils at an angle of rotation along the axial axis of the motor (helically), rather than purely axially (FIGURE 1).…”

Section: Skewed Windingmentioning

confidence: 99%

Design of a HTS 2 MW Electric Motor for Single-Aisle Regional Aircraft

Alvarez,

Satrústegui,

Scheifler

et al. 2023

IEEE Access

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This paper presents the design of a 2 MW superconducting electric machine capable of replacing a conventional regional aircraft turbine. The main objective of this work is to advance in the path towards the more-electric aircraft, by incorporating and assessing in the same design technologies such as a superconducting rotor and its cooling by means of helium at cryogenic temperatures, the skewed armature winding or the oil-flooded cooling of the stator, to obtain high specific power density and efficiency values. Although the use of these technologies is well known in the literature, no work is found to implement all of them simultaneously, which poses great challenges both for their subsequent manufacture and later performance. After showing and justifying each element of the design of the electric machine, the electromagnetic performance of the motor and of the superconducting coils is assessed, it is thermally evaluated so that it does not exceed the strict temperature limits and a mechanical analysis of the elements of the motor is also carried out. The main finding of this work is the validation of the proposed model, and that, even though the designed engine is feasible at the proposed power level, the specific power density and efficiency values would improve in the case of upscaling the engine for implementation in larger aircraft.INDEX TERMS Aircraft propulsion, electric machine, high-power, high-temperature superconductor, regional aircraft.

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Section: Skewed Windingmentioning

confidence: 99%

Design of a HTS 2 MW Electric Motor for Single-Aisle Regional Aircraft

Alvarez,

Satrústegui,

Scheifler

et al. 2023

IEEE Access

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show abstract

“…This necessity results in a lower number of degrees of freedom in terms of winding topologies compared to designing windings with round, stranded conductors. Apart from transposition, which is mandatory, some solutions have been studied to decrease the impact of AC losses, such as the adoption of hairpin conductors with variable cross sections inside the slot [13], the increase of the number of layers [12], pushing conductors towards the slot bottom or the adoption of different materials [14].…”

Section: B Hairpin Conductorsmentioning

confidence: 99%

Analysis of Voltage Distribution and Connections within a High-Frequency Hairpin Winding Model

Pastura

Nuzzo

Barater

et al. 2022

2022 International Conference on Electrical Machines (ICEM)

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In the last years the adoption of hairpin windings is increasing, especially in the automotive sector, mainly due to their inherently high fill factor and electric loading capability.A critical aspect related to the reliability and lifetime of every winding typology is the voltage stress due to the uneven voltage distribution. This phenomenon has already been largely analyzed in conventional stranded conductors, while a few studies are available for hairpin windings. With the spreading of wide bandgap devices, the investigation on voltage distribution becomes an ever-timely topic due to their short rise times. This paper presents an analysis of the uneven voltage distribution triggered within hairpin windings by a low rise time waveform, using a complete high-frequency winding model. The different options to series-connect different paths are investigated, providing simple but essential guidelines to reduce the electrical stress within hairpin windings.

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“…Depending on the conductor dimensions, material and operating frequency, it is possible to estimate the AC/DC loss ratio (Kac) for every winding layer. A brief summary of the adopted theoretical assumptions and formulas can be found in [15], while more details can be found in [24].…”

Section: A Winding Datamentioning

confidence: 99%

“…6 shows the 2D (active length) counterpart, where the average Kac every two layers (ETL) is evaluated for the sake of comparison. From the theory illustrated in [15] and [24], it is known that the value of Kac for each layer is strictly linked mainly to the operating frequency, conductor radial dimension and the position of the layer. In Figures 5 and 6, it can be seen that, in the end winding region, the impact of the layer position is lower but still exists.…”

Section: Pew = P3d-p2dmentioning

confidence: 99%

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On the AC Losses in the End Conductors of Hairpin Windings

Pastura

Notari

Nuzzo

et al. 2022

2022 International Conference on Electrical Machines (ICEM)

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In the last years, several resources have been employed to increase torque and power density values in electrical machines, especially in those intended for transport applications. In this context, the adoption of hairpin conductors is spreading thanks to their inherently high fill factor. Their main drawback is represented by their sensitivity to highfrequency phenomena, which can have a significant impact on the Joule losses and thus on the overall efficiency.While several researches have recently focused on ways to model and reduce such high-frequency losses in the slots, i.e. within the conductors' active sides, a few data are available on their impact in the end winding regions.This work provides an investigation on the AC losses occurring in the end conductors of a hairpin winding traction motor. The losses are determined through 3D finite element simulations for a wide frequency range, and compared against those occurring in the active part of the machine.

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Investigation of Resistivity Impact on AC Losses in Hairpin Conductors

Cited by 13 publications

References 21 publications

Design of a HTS 2 MW Electric Motor for Single-Aisle Regional Aircraft

Design of a HTS 2 MW Electric Motor for Single-Aisle Regional Aircraft

Analysis of Voltage Distribution and Connections within a High-Frequency Hairpin Winding Model

On the AC Losses in the End Conductors of Hairpin Windings

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