Influence of Coil Position on AC Losses of Stator Superconducting Windings of a Synchronous Machine for a 10 MW Wind Turbine

Vargas-Llanos, Carlos Roberto; Lengsfeld, Sebastian; Noë, M.; Arndt, Tabea; Grilli, Francesco

doi:10.1109/tasc.2021.3104983

Cited by 12 publications

(13 citation statements)

References 34 publications

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“…The coil is a scale-down version (1:3) of the stator coil of an electrical machine, it has a racetrack shape and represents one of the three types of coils necessary to build the star configuration introduced in [30]. The dimensions of the coil are presented in figure 2.…”

Section: Coil Geometry and Characterisationmentioning

confidence: 99%

Design and test of a setup for calorimetric measurements of AC transport losses in HTS racetrack coils

Vargas-Llanos

Krämer²,

Noë³

et al. 2023

Supercond. Sci. Technol.

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The estimation and measurement of AC losses in coils based on high-temperature superconductors (HTS) are relevant aspects of HTS applications. They influence the cooling power requirement, operating temperature and efficiency, which can be decisive in the construction and implementation of superconducting equipment, such as superconducting electrical machines. The measurement of losses due to AC transport current (without external magnetic field) is not an easy task. Several efforts have been made to measure these AC transport losses in superconducting coils with a calorimetric approach by trying to minimize the influence of the environment, improve the accuracy and ensure the reproducibility of the results. This work presents the design and construction of a setup to measure transport AC losses in high-temperature superconducting coils based on a calorimetric approach (boil-off method). The evaporated cryogen (nitrogen) related to the dissipation of energy is collected by using a 3D printed bubble collector that guides the gas into a flow sensor. A box-inside-a-box approach is used to surround the measurement chamber with a cryogenic environment. This approach allows re-directing the heat transfer from the surroundings into an intermediate zone (space between external and internal box). Since this intermediate zone operates under cryogenic temperatures, the noise and the heat transfer in the internal part of the setup are reduced. A statistical analysis of the results based on a standard load cycle, average value, and standard deviation calculations allows assessing the variability in the measurements and expressing the results as average value and uncertainty range. The calibration and reproducibility of the measurements are verified with a set of resistors under different conditions and during different weeks. Finally, the AC transport losses in a racetrack coil for an electrical machine application are measured and compared with 3D simulation results based on the homogenization of the T-A formulation.

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Section: Coil Geometry and Characterisationmentioning

confidence: 99%

Design and test of a setup for calorimetric measurements of AC transport losses in HTS racetrack coils

Vargas-Llanos

Krämer²,

Noë³

et al. 2023

Supercond. Sci. Technol.

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“…The elliptical equation for the lift factors which are used to describe the characterization data of superconductors is expressed in Equation (7). The fitted parameters at different temperatures of the measured lift factors from SuperPower Inc. are taken from [13,18] as listed in Table 1. To get more accurate flux density, the nonlinearity of magnetic property of the stator and rotor iron core are taken into account and the function of magnetic strength and flux density of ferromagnetic materials (B-H) [17] are included as in Figure 4.…”

Section: Determination Of Operating Pointsmentioning

confidence: 99%

“…A common way to reduce the AC loss is to employ narrower superconducting tapes. In [13] the AC loss of stator coils reduced from 28 kW to 15.42 kW by changing the superconductor tapes from 4 mm to 2 mm. However, in our case, if we keep the distance between the pancake coils in a slot 2 mm, and use the same lift factors and half the critical current of the 4 mm tape, the total loss of the stator coils is 29.4 kW/m as shown in Table 3.…”

Section: Influence Of the Width Of Superconducting Tapesmentioning

confidence: 99%

“…Hence, the superconducting coils in the studied slot are subjected to magnetic fields from the rotor coils, coils from other slots, and coils from the same slot, that is self-field. In [13] there is a large space for iron materials, and due to the shielding magnetic field effect of iron, the superconducting coils in one slot are mainly subjected to the self-field. This could cause the different results of employing 2 mm tapes.…”

Section: Influence Of the Width Of Superconducting Tapesmentioning

confidence: 99%

“…Hence, in this paper, an in-house code was developed to design superconducting wind generators, taking into account geometry, electromagnetics, superconducting properties, iron properties, and AC loss. The estimation of the AC loss is made through the T-A formulation of Maxwell's equations by employing finite elements within the whole generator domain [11][12][13][14]. This work addresses the design of a 10 MW fully superconducting direct-drive wind generator to present the model and is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

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An Electromagnetic Design of a Fully Superconducting Generator for Wind Application

et al. 2021

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A fully superconducting wind generator employs superconductors in stator and rotor to enable high torque density and low weight, that is, enable an ultra-light electric machine for wind application. However, the level of the AC loss of the stator armature coils is a critical issue, which lacks investigations in the design of the fully superconducting generators. In this paper, an in-house model was developed to analyze the potential of a fully superconducting generator by integrating the electromagnetic design with the AC loss estimation. The electromagnetic model was made through analytical equations, which take into consideration the geometry, the magnetic properties of iron, and the nonlinear E–J constitutive law of superconductors. Since the permeability of iron materials and the critical current of the superconductors depend on the magnetic field, an iteration process was proposed to find their operating points for every electromagnetic design. The AC loss estimation was carried out through finite element software based on the T–A formulation of Maxwell’s equations instead of analytical equations, due to the complexity of magnetic fields, currents and rotation. The results demonstrate that the design approach is viable and efficient, and is therefore useful for the preliminary design of the generator. In addition, it is found that smaller tape width, larger distance between the superconducting coils in the same slot, smaller coil number in one slot and lower working temperature can reduce the AC loss of the stator coils, but the reduction of the AC loss needs careful design to achieve an optimum solution.

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An Electrometric Method with Real-time Transport AC Loss Measurement in Superconducting Tapes Based on Compensation Theory

Song

Yang

et al. 2022

J Supercond Nov Magn

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Influence of Coil Position on AC Losses of Stator Superconducting Windings of a Synchronous Machine for a 10 MW Wind Turbine

Cited by 12 publications

References 34 publications

Design and test of a setup for calorimetric measurements of AC transport losses in HTS racetrack coils

Design and test of a setup for calorimetric measurements of AC transport losses in HTS racetrack coils

An Electromagnetic Design of a Fully Superconducting Generator for Wind Application

An Electrometric Method with Real-time Transport AC Loss Measurement in Superconducting Tapes Based on Compensation Theory

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