Aviation is responsible for around 2.4% of the annual global carbon emissions. Without further measure, with a yearly passenger traffic growth of 3.6-3.8%, CO2 emissions are expected to double by 2050. This substantial impact has been addressed in recent decades, and multiple projects like EU Flightpath 2050 have been launched to tackle this challenge for carbon-free air travel. Various alternatives to conventional aviation fuel have been investigated to fulfill this objective. The most feasible solutions are sustainable aviation fuel (SAF) and hydrogen. Despite e-fuel, which can only be burnt in gas turbines, green hydrogen can be used in combustion engines or to produce electricity through fuel cell stacks in an electric aircraft. Liquid hydrogen, LH2, has nearly three times more energy content per unit mass than jet fuel, which makes it an ideal choice for aviation decarbonization. Several studies have identified LH2 as the long-term solution for long-range flights, replacing sustainable aviation fuel. Using hydrogen in a fuel cell-based electric aircraft has multiple benefits over burning it in gas turbines, including higher efficiency, quieter operation, and elimination of emissions such as NOx and SO2 in addition to CO2. ... mehrTherefore, several companies like Airbus and Boeing have already considered aviation electrification in different configurations, including fully electric, hybrid electric, and turboelectric aircraft. Due to all the benefits, this work focuses on a fuel cell-based fully electric aircraft. With the increased required power, the components size and weight increase substantially, especially the hydrogen tank size. Hence, the powertrain components size and weight must be lighter and more efficient, as higher efficiency leads to lower hydrogen consumption and, consequently, smaller tanks. Superconducting material stands as a promising solution, allowing for power transmission with reduced weight and space and more efficiency. This has been a motivation for considering this technology in several projects in aviation electrification, like Airbus's ASCEND project. Thus, an electric aircraft with a superconducting powertrain provides a unique opportunity for a rapid transition to carbon-free aviation. Such a powertrain includes several components, such as the fuel cell stack, superconducting fault current limiter, DC/AC cables and motor, and DC/AC inverter. With all the benefits, the accurate modeling of the entire powertrain and each component is an important issue that must be addressed. This work presents the approach to model such a powertrain in MATLAB/SIMULINK for system simulation in various flight scenarios. Fuel cell stacks as power source converts hydrogen chemical energy to electric energy. Proton exchange membrane fuel cells (PEMFC) offer suitable properties for aviation applications, hence, this fuel cell type is considered in this work. Fuel cell delivers the power with a non-linear voltage-current variation, meaning that the higher the current, the lower the output voltage. Most research works propose a resistive-capacitive transient behavior for the fuel cell. However, the experiments often show a resistive-inductive behavior or, depending on the fuel cell, a combination of both. In this work, the approach to model any behavior is presented. To prevent the short circuit currents in the powertrain, a resistive superconducting fault current limiter (RSFCL), using high temperature superconducting (HTS) tapes and designed based on the powertrain requirements, is integrated. The lumped-parameter modeling of the RSFCL in adiabatic and non-adiabatic conditions is discussed. The simulation results show the RSFCL effective contribution in limiting the fault current. Moreover, no difference between these conditions during short circuits is observed, while after fault, the non-adiabatic model can predict how long it takes for the coolant to absorb the additional heat generated in the tapes and return them to the superconducting state. The superconducting DC and AC cables are integrated to efficiently transfer the energy from the fuel cell stack to the motor. The specific design of these cables is provided, and they are simulated under different scenarios through different models, including lumped-parameter, and onedimensional (1-D) and two-dimensional (2-D), finite-difference method (FDM) based models. The 2-D model is the only one that can calculate the coolant temperature along the cable length. However, this model is more complicated than other models and has higher computational efforts. The simulation results show that during a short circuit, the lumped-parameter model can still give relatively similar results to the 2-D model as a reference, and the 1-D model is an ideal choice for the simulation of the short-length cables, as temperature rise along the length is negligible. A superconducting motor for the aircraft propeller, which is controlled by the DC/AC inverter, is integrated. This work considers a permanent magnet synchronous motor (PMSM) with significantly small stator resistance due to the superconducting coils. The modeling approach for this motor via a basic electrical equivalent circuit is presented, and the control approach using the field-oriented control (FOC) technique, as the most well-known PMSM control method, is explained. To simulate the DC/AC inverter, its average model is considered, and a fault protection algorithm for the inverter is developed. Finally, the results of the entire powertrain simulation in a simulation flight scenario inspired by a real flight profile are presented and discussed. The integrated powertrain in SIMULINK is also simulated under DC and AC short circuits, providing insights into the contribution of each component in the fault events. The system-level simulation results confirm the design of each component based on the powertrain requirements, lossless impact of the superconducting components and validate the effectiveness of the motor drive control. Short circuit analysis indicates an estimation of the components sizing and the RSFCL contribution in protecting the cables from fault. This study also shows the converter blockage by the fault management algorithm, which results in turning the motor into a generator due to motor inertia, feeding the fault. Since superconducting coils in the motor have a small resistance, the motor produces a substantial current, which might be dangerous. This current can be used as an input for the design and further analysis of the motor with more advanced methods. Overall, by following the approach explained in this work, all the modeled components are adjustable with requirements, which provides a beneficial opportunity to use them in wider power system applications.
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