Papers by Sarah Asma Touhami
After the industrial and the environmental successes of hybridization railways transport, the hyb... more After the industrial and the environmental successes of hybridization railways transport, the hybridization of aviation transport is acquiring more and more consideration. In this context, the European Union in partnership with the aerospace manufacturers, has launched in 2014 a largest research program Clean Sky 2 aiming to reduce aircraft fuel consumptions and noise levels. Clean Sky 2 research program includes several projects among of them: Academic reSearch on Thermal & Electric Components & Systems "HASTECS project" which aims to identify and to develop the most promising technologies for decreasing the weight and increasing efficiency of hybrid propulsion chain. "HASTECS project" is organized around six Work Packages (WPs) dedicated to the components of hybrid propulsion chain, for instance, the WP1 is dedicated to electric motors and the WP3 is dedicated to their cooling systems. Indeed, the estimated reduction fuel consumptions for a short range flight would be 3.5% if the specific power of electric machines and power converters with their cooling systems is respectively increased to 5kW/kg and 15kW/kg for 2025, and also increased to 10kW/kg and 25kW/kg for 2035. The targets are significantly higher than those of today. Specific power planned of the industrial electric machines and power converters is higher than the currently one. However, these specific powers present some limitations which depend on the involved material properties and by environment conditions such as: thermal limitations and partial discharges risk. For reaching targeted specific powers for instance in electric machines, the mechanical, electrical and the magnetic loads linked to the materials and cooling technologies must be increased. However, considering the limitations and the environment constraints, choice of loads should be adequate. Therefore, it is important to develop models and tools allowing assessing the actual and the future technologies which allow achieving the HASTECS targets. The present thesis focuses to the development of models and tools for satisfying the HASTECS targets about the electric machines and their cooling systems. There are several different electric machine topologies, namely: radial flux machines, axial flux machines, permanent magnet synchronous machines, wound rotor synchronous machines, asynchronous machines, etc. Performing for each electric machine topology a model for identifying the most promising technologies is a very complex and laborious task. Nevertheless, an analytical model of non-salient sine wave electric machines associated to load ability concepts characterizes a quite lot of electric machine topologies. Based on it, a Target Setting Tool is developed for assessing electric motor technologies considering limits and constraints while without specifying the electric motor topology. Therefore, very few input data are required to make quick trade-offs on electric motor performances as specific power and efficiency whereas Target Setting is based on huge assumptions. For assessing cooling system weight, sizing specified structure of electric motor is unavoidable. Moreover, studies of others work packages are strongly linked to the electric motor structure. Surface Mounted Permanent Magnet Synchronous Motor topology is one of electric motor topology which satisfies the analytical model of Target Setting Tool. A sizing tool called "SM-PMSM" has been carried out based on Surface Mounted Permanent Magnet topology helpful for others packages for providing more details and for checking the Target Setting Tool validity. Two sizing of electric motors with their cooling systems were carried out using Target Setting Tool, SM-PMSM and others tools performed by WP3 to identify the required technologies for the term medium (2025) and long (2035) term HASTECS targets. The sizing using these tools was checked by finite element analysis.
2019 19th International Symposium on Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering (ISEF)
In 2019, transportation was the fastest growing sector, contributing to environmental degradation... more In 2019, transportation was the fastest growing sector, contributing to environmental degradation. Finding sustainable solutions that pollute less is a key element in solving this problem, particularly for the aviation sector, which accounts for around 2-3% of global CO2 emissions. With the advent of Covid-19, air traffic seems to have come to a fairly permanent halt, but this pandemic reinforces the need to move towards a "cleaner sky" and respect for the environment, which is the objective of the Clean Sky2 program (H2020 EU), the context in which the HASTECS project has been launched in September 2016.
HAL (Le Centre pour la Communication Scientifique Directe), Nov 16, 2020
In this paper, the effects of splitting and twisting conductors on the AC Joule losses are studie... more In this paper, the effects of splitting and twisting conductors on the AC Joule losses are studied. The splitting effects are studied using 2D finite element harmonic analysis. 3D finite element harmonic analyses are performed to study the twisting effects. The results give insights in the understanding of Litz wires and their efficiency in reducing AC Joule losses.
2020 International Conference on Electrical Machines (ICEM), 2020
Sizing equations of radial and axial electrical machines are developed. From these equations, the... more Sizing equations of radial and axial electrical machines are developed. From these equations, the main geometrical parameters of the machines are obtained from the specifications and the loads. Analytical models of the open circuit and armature reaction fields are set up and associated to the sizing equations. This results in more accurate sizing equations. An axial and a radial flux motors are sized for the same loads and the same specifications to check the effectiveness of the sizing approach. Eventually Finite Element Analysis results validate the analytical models.
2018 XIII International Conference on Electrical Machines (ICEM), 2018
In the past, designers develop analytical models that are useful to size rapidly surface mounted ... more In the past, designers develop analytical models that are useful to size rapidly surface mounted permanent magnet synchronous motor with sinusoidal waves and a high specific power. In order to ensure the assumptions of sinusoidal waves, a joint design of the stator winding and the rotor is presented. First, an Halbach permanent magnet array is optimized to obtain the desired airgap magnetic flux density wave. Then, in order to obtain a surface current density wave consistent with the desired wave, the conductor distribution along the stator bore is determined.
Designing the electric motors to propel an aircraft represents a huge challenge. The constraint o... more Designing the electric motors to propel an aircraft represents a huge challenge. The constraint of weight requires such machines to be compact. Besides, the high specific power necessary (a few kW/kg, machine cooling included) leads to an increase of the voltage range of stator winding. Such characteristics increase considerably the risk of partial discharges (PD) in the stator winding. In this paper, the design of electric motors aimed to propel a future hybrid aircraft will be presented. It will be realized using 2 tools.
Quelle puissance specifique pouvons-nous atteindre en fonction des technologies actuelles et fut... more Quelle puissance specifique pouvons-nous atteindre en fonction des technologies actuelles et futures des machines electriques pour la propulsion hybride ? Quelles sont les verrous technologiques qu’il faut soulever pour depasser cette puissance specifique ?
This paper presents a sensitivity analysis based on the Sobol indices which is an essential step ... more This paper presents a sensitivity analysis based on the Sobol indices which is an essential step "on the road of system optimization". Such analysis focuses on electrical propeller subsystem (propellers, gearbox, electric motors) including surrogate design models. A previous study [1] has shown that electromechanical actuators (electric generators and electric motors) involve more than 30% of hybrid electric propulsion system weight. Furthermore, most of the variables used for the electric machine design. The electric motor design model is detailed with the related constraints. A physical analysis based on design parameter sensitivity and parameter couplings are described. This study will permit to remove insensitive variables in view of simplifying the global optimization process to be achieved at the whole powertrain level.
This paper presents electrothermal models for sizing the electric motors with their cooling syste... more This paper presents electrothermal models for sizing the electric motors with their cooling system for Hybrid Aircraft Propulsion. A design approach is proposed to reach high specific powers. An electric motor is sized using tools based on loadability concepts. Its performances are validated by Finite Element Analysis. Cooling system is sized based on adapted hydraulic calculations and temperatures are verified using Lumped Parameter Thermal Model.
International Journal of Applied Electromagnetics and Mechanics, 2019
In order to choose electric machines for transport applications, i.e. automotive, aerospace, rail... more In order to choose electric machines for transport applications, i.e. automotive, aerospace, railway and naval, a tool that can make quick tradeolfs of high specific torque electric motors has been developed. The level of the different technologies involved in an electrical machine can be quantifi ed using the loadability concepts developed by experienced designers. After recalling these concepts, magnetic, electric and thermaJ balances are used to calculate the main sizes of an electric motor according to some targets. Specific power or specifi c torque can then be quickly assessed. The proposed approach is validated by applying the tool to some known high torque industrial motors.
2015 Intl Aegean Conference on Electrical Machines & Power Electronics (ACEMP), 2015 Intl Conference on Optimization of Electrical & Electronic Equipment (OPTIM) & 2015 Intl Symposium on Advanced Electromechanical Motion Systems (ELECTROMOTION), 2015
This paper proposes a new model of asymmetric three-phase three legged transformers for the simul... more This paper proposes a new model of asymmetric three-phase three legged transformers for the simulation of transient operation. In the current literature, several models yield incomplete and inaccurate results, both in the steady-state and transient operations. Among all these models, the idea of using a PI model [5] seemed the most promising. We have improved the model by taking into account the fast and very fast electromagnetic transients. An analysis is performed on over-current and overvoltage in the unbalanced three-phase asymmetrical transient behavior. The simulation results are compared with experimental ones to validate the suggested model.
2015 Intl Aegean Conference on Electrical Machines & Power Electronics (ACEMP), 2015 Intl Conference on Optimization of Electrical & Electronic Equipment (OPTIM) & 2015 Intl Symposium on Advanced Electromechanical Motion Systems (ELECTROMOTION), 2015
In this paper we carried out dynamical modeling studies and analyzed of the three-phase three leg... more In this paper we carried out dynamical modeling studies and analyzed of the three-phase three legged transformers of the laboratory. The unbalance and hysteresis phenomenon are also treated and two models are used, namely the T- and PI-models. The PI-model as developed by De-Léon et al [14] in the EMTP simulator (Electro-Magnetic Transients Program) does not give good results. That is why we proceeded to the correction of this model by reversing the two transformers keeping the same parameters of the magnetizing branch. However, the inductance Lsh determined by a short-circuit test should be reduced to the secondary winding of the second transformer. An adequate correction of the model gave simulation results very similar to those of experimental ones. Another solution giving the same results is presented in this paper. We also addressed the unbalance of the three-phase transformer by the symmetrical components method and by the FPEM (Feature Pattern Extraction Method).
This paper describes a thermal equivalent circuit of Liquid Cooling Totally Enclosed Permanent Ma... more This paper describes a thermal equivalent circuit of Liquid Cooling Totally Enclosed Permanent Magnet Synchronous Machines (LCTE-PMSMs). Conductive heat transfer in all directions is taken into account. Specific care has been taken to represent them by equivalent circuit. The conductive heat transfer in heterogeneous media like slots and the convective heat transfer in the airgap and the end-winding are studied.
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Papers by Sarah Asma Touhami