The Influence Of The Temperature Of Liquid Nitrogen On The Physical Properties Of Powder Magnetic Composites

Kapelski, Dariusz; Jankowski, B.; Przybylski, Marek; Ślusarek, B.

doi:10.1515/amm-2015-0123

Cited by 3 publications

(4 citation statements)

References 2 publications

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“…The frequency range tested varied from 50 Hz to 1 kHz, which aligned very well with the test rig specification. The experimental DC B-H curve for Somaloy ® 700 at 77 K was found in [35] and it exhibited only a slight reduction in B…”

Section: B Core Materials Selectionmentioning

confidence: 99%

“…The Litz wire coil region has adopted the homogenization model presented in Section II. The B-H curve data of the Somaloy ® core have been taken from [35] (relevant to 77 K) due to lack of available data at different temperatures. The cryostat containment vessel was fabricated from Electrolytic Tough-Pitch Cu and was modelled in order to assess any eddy losses due to field fringing: modelling results showed that the maximum Cu bucket loss is 0.5 W, which was assumed to be neglectable.…”

Section: Design Strategymentioning

confidence: 99%

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Electromagnetic Characterization of Hyperconducting Aluminum Litz Wires at Cryogenic Temperatures

Zhang,

Iacchetti,

Smith

et al. 2024

IEEE Access

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Cryogenic electric machines (CEMs) offer significant potential for highly power-dense and ultra-efficient net-zero aircraft. Aluminum (Al) displays superior conductivity to copper (Cu) at cryotemperatures, making Al Litz wires an attractive option for CEM windings to minimize DC and eddy losses. However, accurately quantifying Al Litz wire losses remains challenging, particularly considering their unknown electromagnetic behavior at different cryo-temperatures and frequencies when embedded in iron cores. To address this, a specialized test setup was developed to measure the losses of two customized Al Litz coils, alongside a Cu Litz coil, under varying cryo-temperatures (25 to 77 K) and frequencies (50 to 1000 Hz). A numerical model was also developed using COMSOL, incorporating a temperature-dependent electrical conductivity and a homogenization model for Litz wires with rectangular cross-sections. The model was incorporated into an analytic design procedure to maximize the test-rig loss ratio within the tight space and maximum heat rejection constraints of the cryostat, to allow accurate loss separation. The experimental data aligns closely with the numerical simulations, enabling a comprehensive analysis of the loss characteristics of Al Litz wires. This study provides a detailed design methodology and serves as a valuable resource for developing CEMs for zero-emission electric aircraft.

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Section: B Core Materials Selectionmentioning

confidence: 99%

Section: Design Strategymentioning

confidence: 99%

Electromagnetic Characterization of Hyperconducting Aluminum Litz Wires at Cryogenic Temperatures

Zhang,

Iacchetti,

Smith

et al. 2024

IEEE Access

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“…The litz wires used for the power coil and the LUT were modelled using a homogenised equivalent model to improve the simulation time [23]. Unfortunately, most of the datasheets for the core materials focus on room-temperature properties only, so assumptions and extrapolations to cryogenic temperatures were made, where possible based on previous tests in the literature [24,25]. Table 1 describes the magnetic materials considered for the core of the test rig.…”

Section: Design Criteriamentioning

confidence: 99%

Litz wire loss performance and optimization for cryogenic windings

Manolopoulos

Iacchetti

Smith

et al. 2022

IET Electric Power Appl

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Litz wires operating in a cryogenic environment can potentially improve both the efficiency and power density of electrical machines and passive components. However, due to the low resistivity and high magnetic fields, eddy-current losses may become significant in cryogenically cooled windings, especially in airgap winding arrangements or in the case of significant slot leakage fields, unless the litz wire parameters are carefully chosen. A framework for litz wire loss performance optimization and experimental characterisation at cryogenic temperatures is provided. An optimum operating temperature for minimum loss is derived based on analytical expressions, which highlights the role of litz wire parameters, current density and external field. The proximity loss model, used to calculate the optimum operating temperature, is validated experimentally. Two test rigs with different magnetic cores were designed and built. Copper and aluminium litz wires with a strand diameter down to 0.1 mm were tested in a liquid nitrogen bath with a uniform harmonic external magnetic field up to 0.5 T peak and a frequency up to 1 kHz. Measurements show good agreement with the theoretical results and confirm that the proposed model can be confidently used during the preliminary design of cryogenic windings.

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“…The result of investigation of transversal rupture strength and compressive strength shows that mechanical properties enhance with decreasing temperature [18]. Both of these powders are insulated by dielectric during the production process [17].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Soft Magnetic Composites at the Temperature of Liquid Nitrogen

2017

Self Cite

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Soft magnetic composites are used in a wide range of applications working in different environmental conditions, between others, in different temperatures. Nowadays, devices often work in cryogenic temperatures. The paper shows influence of liquid nitrogen temperature on mechanical properties of soft magnetic composites prepared from ABC100.30 powder bonded by epoxy resin. Mechanical properties of samples were measured in room and liquid nitrogen temperatures. Compressive strength and transverse rapture strength increase with decreasing temperature. This type of soft magnetic composite can be applied in magnetic circuits of devices working in cryogenic temperatures. The results of measurement show that new devices, especially electric machines, working in these temperatures can be designed with higher mechanical loadings than devices working at room temperature.

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The Influence Of The Temperature Of Liquid Nitrogen On The Physical Properties Of Powder Magnetic Composites

Cited by 3 publications

References 2 publications

Electromagnetic Characterization of Hyperconducting Aluminum Litz Wires at Cryogenic Temperatures

Electromagnetic Characterization of Hyperconducting Aluminum Litz Wires at Cryogenic Temperatures

Litz wire loss performance and optimization for cryogenic windings

Mechanical Properties of Soft Magnetic Composites at the Temperature of Liquid Nitrogen

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