PhD Studentship: : High-Fidelity Electromagnetic-Thermal Modelling of Litz Windings for Next-Generation Cryogenic Machines

This 3.5-year PhD project is fully funded; students who are eligible to pay tuition fees at the Home rate are eligible to apply. The successful candidate will receive an annual tax-free stipend set at the UKRI rate (£21,805 for 2026/27) and tuition fees will be paid. We expect the stipend to increase each year. The start date is flexible but we are looking for someone to start as soon as possible.

Transport electrification is central to energy security and net zero. Electrical machines lie at its heart, providing propulsion across road, rail and maritime transport. In mass- and volume-constrained applications such as aerospace, these machines must become substantially more power-dense and efficient, a leap that calls for innovative technologies rather than incremental refinement.

Cryogenically cooled machines offer one of the most promising routes. At extremely low temperatures (around 20 K), the electrical resistance of high-purity aluminium and copper falls by up to a hundredfold, allowing windings to carry far higher currents with drastically reduced DC losses. Built from readily available materials, these “hyperconducting” windings offer a practical path to step-change performance.

However, this benefit comes at a cost. The same reduction in resistance strongly amplifies induced eddy currents, making AC losses a major concern. Litz windings, with thousands of fine, 3D-transposed strands, can mitigate these losses, but at cryogenic temperatures the losses become highly sensitive to temperature. Conductor resistance can change several-fold over a few tens of kelvin, while low heat capacity means even small losses cause significant temperature rises. Losses and temperature are therefore tightly coupled, making accurate loss prediction and assessment of thermal stability both critical and highly challenging.

This PhD project will tackle this challenge by developing high-fidelity, computationally efficient electromagnetic–thermal models of Litz windings at cryogenic temperatures, and using them to derive design guidelines for next-generation power-dense cryogenic machines with ultra-high-efficiencies.

You will:

• extend established in-house analytical electromagnetic models to practical Litz windings, using reduced-order and data-driven AI methods for rapid, accurate loss prediction, verified against finite element simulations;
• integrate these models with an existing thermal solver into a two-way coupled electromagnetic–thermal framework;
• validate the framework through simulation and experiments on Litz winding samples, using an existing cryogenic test facility;
• use the validated framework to understand the coupled behaviour, identify key design factors and optimise winding designs.

You will join the Energy Conversion group in the Department of Electrical and Electronic Engineering, with weekly supervision from a team with complementary electromagnetic and thermal expertise. You will have access to established models, dedicated simulation software and cryogenic test facilities, so you will build on a solid foundation rather than starting from scratch. Training will cover electrical machine fundamentals, analytical and finite element modelling, data-driven methods, programming and cryogenic testing, alongside the University’s doctoral skills training.

This project suits a motivated candidate with a background in electrical, electronic or mechanical engineering, physics or a related discipline, who enjoys combining theory, simulation and experiments. Experience in electrical machine design, electromagnetic fields, finite element analysis, thermal management or programming (e.g. MATLAB, Python) is desirable but not essential.

Applicants should have, or expect to achieve, at least a 2.1 honours degree or a master’s (or international equivalent) in a relevant science or engineering related discipline.

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