Modeling, Optimal Design, and Control of Linear Induction Motors for Medium-to-High-Speed Ground Transportation Systems
To meet the Paris Agreement target of limiting global warming to 1.5°C, the International Energy Agency stresses the urgent need for rapid and transformative actions in all sectors. In 2022, transportation accounted for about 25% of global CO2 emissions, making decarbonization a critical priority. Among transportation modes, rail is the least carbon-intensive and is expanding significantly worldwide. High-speed rail, in particular, provides a viable alternative to short- and medium-haul flights, helping reduce aviation-related emissions. Innovative, sustainable transportation technologies are gaining interest as complementary solutions to rail expansion. They diversify land transportation and help reduce aviation-related emissions. Governments, especially the European Commission, have shown renewed commitment to advancing high-speed systems. This political interest has brought back interest in established but underutilized technologies like Hyperloop and maglev trains. The propulsion of maglev and Hyperloop systems is typically achieved using Linear Electrical Machines (LEMs), which are types of electrical machines that produce linear motion by generating a direct and contactless thrust force along a straight-line path. Among various types of LEMs, Linear Induction Motors (LIMs) stand out as promising candidates for maglev propulsion. LIMs correspond to the linear counterpart of conventional Rotating Induction Motors (RIMs) and may offer significant advantages compared to other LEMs, such as simpler construction, lower cost, and scalability. However, LIMs have traditionally been restricted to low-speed, short-haul applications due to their lower efficiency and gravimetric force densities than other LEMs. This thesis explores the potential of LIMs for medium- to high-speed maglev ground transportation systems, focusing on the integration of Propulsion and Levitation (PL) or Propulsion and Guidance (PG) functionalities into a single motor for an all-in-one maglev system. The core of the thesis is the development of a highly accurate and computationally efficient analytical model of LIMs that allows for the calculation of motor electromagnetic fields, forces, and efficiency. The proposed analytical model has been validated through comparisons with Finite Element Analysis (FEA) simulations and measurements from a custom-made experimental platform, demonstrating excellent accuracy and superior computational efficiency compared to FEA models. The proposed analytical model is utilized in the thesis to enhance the performance of Single-Sided LIMs (SLIMs), focusing particularly on increasing their gravimetric force densities, and to demonstrate the potential of SLIMs for a MHS maglev system with PL or PG functionalities integrated into the same motor. The thesis also proposes an optimization framework for the design of SLIMs, in which the developed analytical model and the performance enhancement techniques mentioned above have been combined into a multiobjective optimization problem. The objective is to maximize the Levitation-to-Weight Ratio (LWR) and the efficiency of SLIMs for a reduced-scale Hyperloop prototype operated at the EPFL Hyperloop test infrastructure. Finally, a control strategy is proposed to achieve a decoupled, simultaneous, and electromagnetic drag-less control of PL in SLIMs, thereby unlocking their potential to combine these functionalities into a single motor.
École Polytechnique Fédérale de Lausanne
Prof. Sophia Haussener (présidente) ; Prof. Mario Paolone, Dr André Hodder (directeurs) ; Prof. Alfred Rufer, Prof. Mauro Carpita, Prof. Luca Zarri (rapporteurs)
2025
Lausanne
2025-08-04
11350
236