LIMITLESS Project
Linear Induction Motor Drive for Traction and Levitation in Sustainable Hyperloop Systems
51885.1 IP-ENG
Duration
48 Months
Start Date
01-07-2021
FINANCED BY
Innosuisse
ACADEMIC Partners
IMPLEMENTATION PARTNERS
Description:
According to the Swiss strategy on mobility (“Avenir de la mobilité en Suisse, Cadre d’orientation 2040 du DETEC”), future transportation systems should be sustainable, efficient and based on light infrastructures. While this strategy is aligned with global trends in the transportation sector, it poses several technical challenges.
A promising solution are high-speed trains, notably based on Hyperloop technology. Composed of two main elements, an electric vehicle and a controlled environment confined infrastructure, the Hyperloop has the potential to disrupt intra-continental travels, while being sustainable at the same time. While high-speed solutions, such as Maglev, exist, the cost of their infrastructure is prohibitive as it requires an active and sophisticated rail.
Swisspod’s efforts focus on flipping the Maglev concept by integrating the energy reservoir in the vehicle propelled by an optimally-designed Linear Induction Motor (LIM) that makes the infrastructure passive. The major limitation of an energy-autonomous vehicle is its range. Since current battery energy densities cap at a few hundreds of Wh/kg, the autonomy is limited by mass constraints and the efficiency of LIMs. The LIM is a good candidate for high-speed travel when compared to its rotating equivalent.
However, current LIM solutions are known to be less energy efficient and have a lower power factor than rotating motors. Those limitations are associated with LIM’s finite length. Although nowadays Power Electronics (PE) make available efficient power converters, the use of conventional solutions faces fundamental challenges to reach high-speeds. The goal of this project is to overcome these limits.
Contact Person:
georgios.sarantakos@epfl.ch
Author(s):
Abstract:
Traditional magnetic levitation trains (maglev) generally use two or three separate systems to perform propulsion, levitation, and guidance (PLG) functionalities. Linear electromagnetic motors (LEMs) may be used for propulsion, electromagnetic suspension (EMS), or electrodynamic suspension (EDS) for levitation and guidance. Although considerable effort has been made to integrate these functionalities in a single LEM, a maglev with combined PLG is not yet available. This article proposes a solution to increase the levitation force of a singlesided linear induction motor (SLIM) at medium-to-high speed by adding an appendix of ferromagnetic material to its rear section. The appendix’s role is to conserve the magnetic flux density at the SLIM rear, which would otherwise be unexploited, and use it to generate additional levitation. The impact of the tail size on the levitation force has been modeled and added to an analytical model developed in previous works. The accuracy of the proposed model has been numerically and experimentally validated through f.e.m. and measurements from a custom-made test bench. A sensitivity analysis on the appendix length for a realistic-size SLIM is finally carried out, proving the effectiveness of the proposed solution and demonstrating the potential of SLIMs for combined PLG for medium-to-high-speed magnetic levitation vehicles.
Author(s):
Abstract:
Literature on linear induction motors (LIMs) has proposed several approaches to model the behavior of such devices for different applications. In terms of accuracy and fidelity, field analysis-based models are the most relevant. Closed-form or numerical solutions can be derived, based on the complexity of the model and the underlying hypotheses. In terms of simplicity, equivalent circuit-based models are the most effective, since they can be easily integrated into optimization frameworks. To the best of the authors’ knowledge, the literature has not yet provided a computationally efficient LIM analytical model that considers the main characteristics of this type of motor altogether (i.e. finite motor length, magnetomotive force (mmf) space harmonics, slot effect, edge effect, and tail effect) and that is numerically and experimentally validated, especially at high speed (i.e. v ≃ 100ms -1 ). Within this context, this paper proposes a field analysis-based pseudo-three-dimensional model of LIMs that explicitly takes into account the above-mentioned effects. The derived closed-form solution makes the model computationally more effective than traditional f.e.m. models and, therefore, suitable to be coupled with optimization frameworks for optimal LIM design. The performance and accuracy of the proposed model are assessed through numerical simulations and experimental measurements, carried out by means of a dedicated test bench.
Author(s):
Abstract:
Linear electromagnetic motors (LEMs) have been proposed, developed and used to propel high-speed (i.e. speed > 100 m/s) levitating vehicles. However, few real implementations have demonstrated the feasibility of these machines at such speeds. Furthermore, LEMs are expected to be enabling technologies for levitating vehicles traveling at near sonic speed, such as the Hyperloop concept. This paper presents a systematic review of modeling, design and performance assessment of LEMs used (or proposed) for the propulsion of levitating high-speed vehicles. Among all the possibilities, those that have received the most attention since the 1960s, along with the first magnetic levitation train concepts, are discussed. Classified by operating principle and topology, the LEMs are compared in terms of design and performance via specific key performance indicators. The performance of the various proposed LEMs is assessed on the basis of data available in the literature.
Author(s):
Abstract:
This article describes a field-based analytical model of single-sided linear induction motors (SLIMs) that explicitly considers the following effects altogether: finite motor length, magnetomotive force mmf space harmonics, slot effect, edge effect, and tail effect. The derived closed-form solution of the system’s differential equations makes the model computationally more efficient than traditional finite elements (f.e.m.) models, and, therefore, more suitable for SLIM design optimization processes. The computational performance and accuracy of the proposed analytical model are validated through numerical simulations (via COMSOL Multiphysics) and experimental measurements carried out through a dedicated test bench.