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1.	Acquaviva, Alessandro, 1987, et al. (författare) Computationally Efficient Modeling of Electrical Machines With Cooling Jacket 2019 Ingår i: IEEE Transactions on Transportation Electrification. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2332-7782. ; 5:3, s. 618-629 Tidskriftsartikel (refereegranskat)abstract Modeling of electrical machines is a multiphysics problem. Depending on the phenomena of interest and the computational time constraint, this can be done at different levels of detail. In this article, the main approaches to model the thermal behavior of electrical machines with a liquid cooled casing around the stator (often referred to as cooling jacket) are analyzed and a novel approach is presented. The proposed method aims at creating computationally efficient 3-D multiphysics models of electrical machines with liquid cooled jacket. This model is based on the assumption of a fully developed flow in the cooling jacket which allows to scale the computational fluid dynamics (CFD) simulation to 1-D. The slot with a two layer concentrated winding and potting material is modeled using a composite material comprising of both the conductors and slot filler. Similarly, a unified material is used to model the end-windings. Experimental results on a traction machine for vehicle applications are presented showing good agreement with the simulations. Also, a comparison with a 3-D CFD is presented to verify the pressure drop in the pipe bend. Finally, the model is used to simulate a dynamic load cycle, which would be computationally extremely demanding with combined 3-D CFD and thermal FEA of the machine and its cooling.
2.	Acquaviva, Alessandro, 1987, et al. (författare) Electromagnetic and Calorimetric Validation of a Direct Oil Cooled Tooth Coil Winding PM Machine for Traction Application 2020 Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 13:13 Tidskriftsartikel (refereegranskat)abstract Tooth coil winding machines offer a low cost manufacturing process, high efficiency and high power density, making these attractive for traction applications. Using direct oil cooling in combination with tooth coil windings is an effective way of reaching higher power densities compared to an external cooling jacket. In this paper, the validation of the electromagnetic design for an automotive 600 V, 50 kW tooth coil winding traction machine is presented. The design process is a combination of an analytical sizing process and FEA optimization. It is shown that removing iron in the stator yoke for cooling channels does not affect electromagnetic performance significantly. In a previous publication, the machine is shown to be thermally capable of 25 A/mm2 (105 Nm) continuously, and 35 A/mm2 (140 Nm) during a 10 s peak with 6 l/min oil cooling. In this paper, inductance, torque and back EMF are measured and compared with FEA results showing very good agreement with the numerical design. Furthermore, the efficiency of the machine is validated by direct loss measurements, using a custom built calorimetric set-up in six operating points with an agreement within 0.9 units of percent between FEA and measured results.
3.	Alatalo, Mikael C D, 1959, et al. (författare) Electric Machine Design for Traction Applications Considering Recycling Aspects- Review and New Solution 2011 Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. - 9781612849720 ; , s. 1836-1841 Konferensbidrag (refereegranskat)abstract With the expansion of the fleet of electric and hybrid electric vehicles worldwide, it is of interest to consider recycling aspects of the parts that are introduced in these new vehicles. This paper focuses on the design of electrical machines considering recycling of its components. The materials to consider are mainly copper, core materials such as lamination steel or iron, and permanent magnets. One design is suggested with a core material of soft magnetic composites which is very suitable for recycling as it is a brittle material and thus simplifies the access of the copper winding. The suggested design shows to have similar performance to a similar size and similar weight commercial permanent magnet electric machine made with steel lamination. © 2011 IEEE.
4.	Alatalo, Mikael C D, 1959, et al. (författare) Evaluation of three cooling concepts for an electric vehicle motor - 3D models 2020 Ingår i: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. ; , s. 867-873 Konferensbidrag (refereegranskat)abstract The aim of this paper is to model and analyze the performance of a permanent magnet electric motor for an electric vehicle with different cooling duct designs; wave-cooling duct, spiral cooling duct, and cooling in potted end regions. The comparison between designs are made first by using a 2way coupled electromagnetic model and a computational fluid dynamic (CFD) software for a set of operating points, and then by using lumped parameter models (and boundary conditions from the 2-way coupled model) to calculate the drive system performance over the motor operating region. The first task is described in this paper and the second task in an accompanying paper. It is found that the three cooling system designs give similar efficiencies and average component temperatures with some exceptions depending on the loss distribution but also that the hottest regions have different locations. However, the relatively high flow rate of 10 l/min used in the comparison, results in efficient cooling and low temperature difference between the coolant and the aluminum housing.
5.	Franzke, Randi, 1989, et al. (författare) Measurements and CFD Modeling of Temperatures in the Engine Compartment of a Hybrid Electric Vehicle 2018 Ingår i: 2017 IEEE Vehicle Power and Propulsion Conference, VPPC 2017 - Proceedings. ; 2018-January Konferensbidrag (refereegranskat)abstract In this article the temperature distribution within the engine compartment of a hybrid electric vehicle is experimentally and numerically investigated. The aim of this study is to develop a simulation model that captures the thermal behaviour of the electrical components for different driving conditions. For the experimental part, temperature sensors are placed at various locations inside cooling hoses as well as on the hoses and on various components. Using the commercial computational fluid dynamics (CFD) software StarCCM+, a complete vehicle simulation is set up for the same model. A comparison between the measurements and the numerical results shows good results. The increase in cooling media temperature when passing through the CIDD (Combined Inverter and DC/DC converter) is determined with a 10\,\% deviation, also the CIDD surface temperatures are well predicted. For the Electric Rear Axle Drive (ERAD) the surface temperatures lie within the requested 5k interval for the majority of measurement points, especially on the exterior of the cooling channel around the electric machine.
6.	Grunditz, Emma, 1980, et al. (författare) Acceleration, Drive Cycle Efficiency, and Cost Tradeoffs for Scaled Electric Vehicle Drive System 2020 Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 56:3, s. 3020-3033 Tidskriftsartikel (refereegranskat)abstract This article investigates and quantifies, for varying drive system ratings (0.5-2.0 times the rating of a small and large reference system), the tradeoff relations between the electric vehicle acceleration performance and energy consumption during a wide range of drive cycles, using detailed load-dependent loss models. Additionally, the results are related to estimated drive system cost by transparently determined scalable electric motor and inverter cost models. When reducing the system rating to half, the cost is 83% of the small reference system and 76% of the large. The acceleration time (0-100 km/h) decreases nonlinearly with increasing system rating. Interestingly, the drive cycle energy consumption generally decreases with decreasing drive system rating, and most cycles show a minimum consumption with a downscaled drive system. For the small system, the strongest impact was noted for the HWFET cycle where the energy consumption is reduced 2% when downscaling the drive system by 0.5 relative to the reference system. For the large system, NYCC shows the largest reduction in energy consumption: 4% when scaled by 1.6 relative to the reference system.
7.	Grunditz, Emma, 1980 (författare) BEV Powertrain Component Sizing With Respect to Performance, Energy Consumption and Driving Patterns 2014 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract In this thesis, various drive cycles, legislative, official real-world and measured withinthe frame of the project, have been studied and characterized in terms of speed and accelerationcycle parameters, as well as acceleration and speed distribution. The objective was toassess typical vehicle usage on different road types, but also to study the implication on vehicleenergy consumption due to the drive cycle’s characteristics. For this evaluation, threereference vehicles were designed after different set performance requirements, with data onexisting BEVs as a frame of reference. An available traction motor, power electronic moduleand battery cell were utilized, where the motor was scaled by active length. Finally, theconsequence of downsizing the electric drive system in terms of energy consumption andperformance was also studied.Through comparison between legislative together with official real-world cycles andmeasured drive cycles, it was found that even though the measured cycles reach higherpeak acceleration levels for a certain speed level, they still spend only slightly more time athigher levels of acceleration compared to the official cycles, at least on average over a groupof similar cycles. During the powertrain sizing regarding torque and power, it turned out thatthe acceleration requirementwas dominating over other requirements such as top speed, andgrade levels. The analysis shows that for two cycles with similar speed parameters such asmaximum and average speed and time share at low speed, but where the speed time tracesare very different with many more speed fluctuations in one cycle compared to the other,in combination with generally higher acceleration levels, the increase in net battery energyconsumption per distancemay be as high as 28% for the cycle with more speed fluctuations.By down-scaling the electric drive system of the City car by 40%, the net battery energy perdriven distance for low speed cycles increased by about 3−6%, while three of the cyclescould not be fulfilled due to limited acceleration capability.
8.	Grunditz, Emma, 1980, et al. (författare) Characterizing BEV Powertrain Energy Consumption, Efficiency, and Range During Official and Drive Cycles From Gothenburg, Sweden 2016 Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 65:6, s. 3964 - 3980 Tidskriftsartikel (refereegranskat)abstract In this paper, the energy consumption per distance of a battery electric vehicle (BEV) is comprehensively investigated for various official and gathered real-world drive cycles, including the powertrain's cycle average efficiency. The powertrain component losses are modeled with a high level of detail, and they are functions of both speed and load. It is shown that the difference in calculated drive-cycle energy consumption may be up to 16% when using two different acceleration approximation methods and one speed sample per second, which is an interval commonly used among drive cycles. In contrast to combustion engine vehicles (CEVs), BEV energy consumption per distance generally increases with increasing cycle speed levels, and time spent at high speed levels have the largest influence on the consumption. The effect of acceleration on energy consumption is seen to be considerably reduced due to regenerative braking as it reduces the consumption by up to 49% on an acceleration intense cycle. Even when the regenerative area is limited to about half, the decrease in driving range is less than 1% for most cycles. By introducing the concept of overconsumption, it is shown that much time spent at high levels of acceleration is one of the largest contributors to excess energy consumption for BEVs. Furthermore, the found cycle average powertrain efficiencies are quite similar between the different cycles, with 82%–90% during propulsion and only slightly lower during braking, i.e., much less speed dependent than for CEVs.
9.	Grunditz, Emma, 1980 (författare) Design and Assessment of Battery Electric Vehicle Powertrain, with Respect to Performance, Energy Consumption and Electric Motor Thermal Capability 2016 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract In this thesis, various drive cycles, legislative, official real-world and measured, have been studied and characterized based on their speed and acceleration content. Three reference vehicles (a City car, a Highway car and a Sport car) were conceptualized after performance requirements, with data on existing battery electric cars as a frame of reference. The acceleration performance, energy consumption and efficiency of the powertrain, comprising a traction motor, a power electronic module and a battery, was determined and analyzed for the various drive cycles. Furthermore, the consequence on acceleration performance, drive cycle fulfillment and energy consumption during re-scaling of the electric drive system was studied. Moreover, the electromagnetic losses for four different slot areas were compared, along with the thermal steady state and transient over load as well as temperature development during drive cycles. Through comparison between official and measured drive cycles, it was found that even though the measured cycles reach higher peak acceleration levels for a certain speed level, on an average they still spend only slightly more time at higher levels of acceleration compared to the official cycles. The resulting cycle average powertrain efficiencies were fairly similar for both the official and measured cycles, and showed to be slightly higher for cycles that spend more time at higher speed levels. During the powertrain sizing regarding torque and power, the acceleration requirement turned out to dominate over other requirements such as top speed, and grade levels. It was found that a down scaling of the electric power train resulted in an energy consumption down to 94% of the original powertrain size. The small slot geometry had the highest peak losses during the drive cycles, however, on a cycle average it had the lowest losses for many cycles. This fact, in combination with the highest peak torque and lowest material cost, makes it a very interesting option as an electric vehicle traction motor.
10.	Grunditz, Emma, 1980, et al. (författare) Drive Cycle Evaluation and Consumption of PM Motors for a Typical Battery Electric City Bus 2023 Ingår i: 2023 IEEE International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles & International Transportation Electrification Conference (ESARS-ITEC). - 9798350346893 Konferensbidrag (refereegranskat)abstract Four permanent magnet electric machines for a typical battery electric city bus (BECB) are compared regarding drive cycle energy consumption during 18 official and one logged bus drive cycle. Two machine types are used; an interior permanent magnet synchronous machine (IPMSM) with a two layer distributed winding (DW), and an IPMSM with tooth coil windings (TCW), both with either copper or aluminum winding material. The results are aimed for a life cycle assessment study of electric machines in a typical BECB. A conducted BECB market survey is shortly summarized, and 40 official bus drive cycles are characterized using the chosen bus dimensions.
11.	Grunditz, Emma, 1980, et al. (författare) Electric Vehicle Acceleration Performance and Motor Drive Cycle Energy Efficiency Trade-Off 2018 Ingår i: Proceedings 2018 XIII International Conference on Electrical Machines (ICEM). - 2381-4802. - 9781538624777 ; , s. 717-723 Konferensbidrag (refereegranskat)abstract During passenger car design, both high acceleration performance and low energy consumption are targeted. For battery electric vehicles (BEVs) to reach these objectives, it is vital to evaluate the consequences that different motor design choices have on them. This paper presents a quantitative analysis of the effect on acceleration performance and motor losses during BEV driving, when the motors power rating is varied. Two reference traction machines are sized and evaluated using finite element analysis, for a small and large BEV. Via axial scaling, the motors' power is then varied linearly by factors between 0.5-2, and the changes in motor losses are accounted for. Both the 0-100km/h acceleration time and motor losses during several low, middle and high speed drive cycles are calculated. Depending on drive cycle, scale factors between 0.5-1.0 give the lowest motor losses with both BEVs. The lowest are down to 67% and 61 % of the losses with scale factor 1.0, for the small and large BEV respectively. Yet, then the acceleration time varies non-linearly between 28s-13s for the small BEV and 20s-10s for the large, respectively. Hence, the results demonstrate a clear trade-off between targeting high acceleration performance and low energy consumption during driving.
12.	Grunditz, Emma, 1980, et al. (författare) Electric Vehicle IGBT Power Module Sizing and Drive Cycle Energy Efficiency for Various Switching Frequencies-Based on a Scalable Module Model 2018 Ingår i: 2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe. Konferensbidrag (refereegranskat)abstract Preferably, in electric vehicles, the drive system components are sized to comply with performance requirements while simultaneously striving to keep energy losses and cost down. One of the parameters affecting the inverter's losses is the selected switching frequency. Hence it could also play a role during sizing. In this paper an electric vehicle IGBT power module is sized using various switching frequencies, against a scaled reference electric machine. As a tool for this assessment a scalable power module model is suggested, that scales with current rating. Finally, the impact on drive cycle efficiency is determined for various inverter ratings designed for different switching frequencies.
13.	Grunditz, Emma, 1980, et al. (författare) Evaluation of three cooling concepts for an electric vehicle motor - Lumped parameter models 2020 Ingår i: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. ; 23 August 2020, s. 860-866 Konferensbidrag (refereegranskat)abstract Three different cooling solutions for the same permanent magnet electric vehicle traction machine are compared using 2D finite element method generated loss maps and a thermal lumped parameter network. Two water jackets, with a wave and a spiral shaped channel, are compared to an end-shield cooling channel with end winding potting. The coolant convection is estimated using 3D conjugate heat transfer simulation software, presented in an accompanying paper. The continuous and overload torque capability are determined as well as the winding temperatures and energy losses during a set of low, middle and high-speed drive cycles. The results indicate very similar performance for the two water jackets. With the end-shield cooling the continuous torque is considerably higher at low speed levels, higher torque levels can be sustained for a certain time, and the drive cycle winding temperatures and losses are lower compared to the cooling jackets.
14.	Grunditz, Emma, 1980, et al. (författare) Performance Analysis of Current BEVs - Based on a Comprehensive Review of Specifications 2016 Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 2:3, s. 270-289 Forskningsöversikt (refereegranskat)abstract This paper aims to provide an analysis of BEV performance that is based on a comprehensive collection of specifications of over 40 currently globally available battery electric vehicles (BEVs). The analysis comprise dimensional, powertrain and performance data. The collected data is provided in the paper to facilitate further academic studies. There is a wide variety of BEVs from small to large as well as high performing sedans and sport cars. It was found that all BEVs are using Li-ion batteries with specific energy of 55-170 Wh/kg, and that battery weights are representing 13%-37% of the vehicle weight. Furthermore, the majority of the BEVs are using permanent magnet motors, where some indicate power densities of 1.5-3.1 kW/kg. The specified NEDC driving range varies between 85- 528 km, and the energy consumption between 117-268 Wh/km. A rough estimation indicates that the powertrain’s share of the net energy consumption during NEDC may be up to around 40%-54%.
15.	Grunditz, Emma, 1980, et al. (författare) Thermal capability of electric vehicle PMSM with different slot areas via thermal network analysis 2021 Ingår i: eTransportation. - : Elsevier BV. - 2590-1168. ; 8 Tidskriftsartikel (refereegranskat)abstract In this paper, the effect that a varied stator slot size has on the efficiency and thermal capability of a permanent magnet synchronous machine for an electric vehicle, is evaluated and quantified. A machine with four differently sized slot areas was electromagnetically evaluated with finite element analysis, and thermally with a lumped parameter network model. By decreasing the slot size while keeping other dimensions fixed, the core losses reduce due to the wider magnetic path, whereas the winding losses increase. Additionally, a higher maximum torque is reached due to reduced saturation. Results are compared in the machine's torque-speed operating area regarding machine-part and total losses, continuous torque and transient overload capability, as well as during 19 low, middle and high-speed drive cycles regarding energy losses and peak winding temperature. The largest slot showed the lowest winding losses and thus the highest thermally limited torque capability. In contrast, the energy losses with the largest slot were the highest in 13 of the drive cycles, and the lowest in 11 of them with the smallest slot due to its lower part load (i.e. core) losses. The smallest slot would also result in the lowest material cost since it has the least copper.
16.	Grunditz, Emma, 1980, et al. (författare) Three traction motors with different magnet materials — Influence on cost, losses, vehicle performance, energy use and environmental impact 2018 Ingår i: 2018 Thirteenth International Conference on Ecological Vehicles and Renewable Energies (EVER). ; , s. 1-13 Konferensbidrag (refereegranskat)abstract The aim of reducing both cost and environmental impact of automotive electric traction motors motivates the examination of motor performance when using magnets of varying strength and materials. Such investigations have attracted increasing interest in recent years. Given the same take-off torque capability, three motors are compared that have the same stator geometry but different magnet materials in the rotor; two PMSMs - one with Nd(Dy)FeB and one with SmCo magnets - and one PMaSynRM with strontium-ferrite magnets. To compensate the weaker magnets, their corresponding core stacks are prolonged. The resulting torque capability at high speed levels is lower for the SmCo PMSM and ferrite PMaSynRM compared to the Nd(Dy)FeB PMSM. The ferrite PMaSynRM has the poorest dynamic vehicle performance, but also the lowest energy losses over a wide range of drive cycles. In addition, the ferrite based motor option has the lowest environmental impact during manufacturing as well as the lowest material cost estimate. The SmCo motor has slightly lower losses than the Nd(Dy)FeB, but the highest material cost. Certainly, the result signals that further in-depth studies of the described PMaSynRM are of high relevance.
17.	Grunditz, Emma, 1980 (författare) Traction Motor for a Battery Electric City Bus - Specification and Drive Cycle Evaluation, Based on Comprehensive Data Collection 2020 Rapport (övrigt vetenskapligt/konstnärligt)abstract This internal, yet official, report serves as base for selecting the specification of a propulsion electric motor for a typical Battery Electric City Bus (BECB). The motor and the bus data are used as references in the research project Circular Economy for Electric Machines, sponsored by the Swedish Energy Agency. Additionally, found official bus drive cycles are presented and characterized, as well as four logs of real world driving of a battery electric city bus in Gothenburg, Sweden. Then, the energy consumption of the reference bus with the reference electric motor efficiency map are calculated and compared to found official data on energy consumption of similar size battery electric city buses. Finally, related bus and electric bus market statistics and projections are summarized. In general, this report aim to provide background data for further analysis, which is why deeper analysis is left out of the report.
18.	Haghbin, Saeid, 1977, et al. (författare) Switched Reluctance Motor in Electric or Hybrid Vehicle Applications: A Status Review 2013 Ingår i: IEEE Conference on Industrial Electronics and Applications (ICIEA 2013). - 9781467363211 ; , s. 1017-1022 Konferensbidrag (refereegranskat)abstract Drive systems based on a switched reluctance motor (SRM) are important alternatives in traction applications because of the motor simple and robust structure without using rare-earth permanent magnets. In this paper, different aspects of the SRM-based drive systems for the vehicle traction are presented and reviewed. Motor design and comparison with the permanent magnet motors, power electronics, simulation, control, and thermal design of the drive are explained and discussed.
19.	Hsieh, Meng-Ju, 1985, et al. (författare) Improved Parametric Representation of im from FEM for More Accurate Torque Predictions 2022 Ingår i: 2022 International Conference on Electrical Machines, ICEM 2022. ; , s. 599-605 Konferensbidrag (refereegranskat)abstract In this work, an updated methodology to determine the parameters of three-phase induction machines (IMs) is developed and presented. The goal of this determination is for a better representation of machines for the further applications of the parameter-based control system operated with different stator flux linkage levels, such as automotive applications. First, the theory of the T-form model (TFM) and the inverse Γ-form model (IGFM) are reviewed. The former review becomes the brick of the following interpretation of the developing methods for identifying these parameters. Moreover, a 2D electromagnetic finite element method (FEM) model of a 15kW IM is utilized to demonstrate the strength of the methodology on a real machine. Lastly, a comparison of results using the conventional test and the newly proposed method is presented, showing improvement.
20.	Hsieh, Meng-Ju, 1985, et al. (författare) Improved Parametric Representation of IM from FEM for More Accurate Torque Predictions: Simulations and Experimental Validations 2024 Ingår i: 2022 IEEE International Conference on Environment and Electrical Engineering and 2022 IEEE Industrial and Commercial Power Systems Europe, EEEIC / I and CPS Europe 2022. - 1939-9367 .- 0093-9994. ; In Press Tidskriftsartikel (refereegranskat)abstract In this work, an updated methodology to determine the parameters of three-phase induction machines (IMs) is developed and presented. The goal of this determination is to achieve a better model representation of induction machines for the usage of a circuit-based control system. First, the theory of the T-form model (TFM) and the inverse Γ-form model (IGFM) are reviewed. The former review becomes the foundation of the following interpretation of the developing methods for identifying the needed parameters. Next, a 2D electromagnetic finite element method (FEM) model of a 15kW IM is utilized to demonstrate the strength of the methodology on a real machine. Furthermore, a comparison of results using the conventional test and the newly proposed method is presented, demonstrating the strength of the proposed procedure with enhanced accuracy for the torque and slip prediction. Lastly, experimental results using a 15kW IM are utilized to demonstrate the usefulness of the proposed parameter determination procedure.
21.	Jansson, Elisabet, 1989, et al. (författare) Convergence of Core Losses in a Permanent Magnet Machine, as Function of Mesh Density Distribution, a Case-Study Using Finite-Element Analysis 2020 Ingår i: IEEE Transactions on Energy Conversion. - 1558-0059 .- 0885-8969. ; 35:3, s. 1667-1675 Tidskriftsartikel (refereegranskat)abstract To limit numerical inaccuracies in electromagnetic finite element analysis, the mesh resolution needs to be set with care. Within electric vehicle propulsion, core losses are highly important while excessive simulation times should be avoided, due to the wide operating range. This paper investigates the procedure of achieving core loss convergence, in all parts of a permanent magnet synchronous machine, by varying mesh density. The finite element analysis is done in Ansys Maxwell and the core loss error is quantified by an estimated fully converged result. Two approaches to mesh tuning are compared. It is found that interdependence, between the mesh density in one part and the core loss in another, should be considered. The required mesh resolution is found to differ among operating points. Finally, the flexibility offered by this convergence method is shown. Once the convergence behaviour has been identified, a mesh can be found for any desired compromise of error and simulation time. For the investigated case, the estimated error in total core loss is below 1.2% when an angular machine segment covering one pole, is modelled with 15 500 mesh elements. Reducing the number of mesh elements to 7 200 gives an error below 3.3%.
22.	Jansson, Elisabet, et al. (författare) Impact of Saturation and Scaling on the Field Weakening Performance of an Interior PM Machine 2020 Ingår i: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. - 9781728199450 ; , s. 1136-1142 Konferensbidrag (refereegranskat)abstract If magnetic saturation is neglected, powerful visual tools exist for understanding field weakening in interior permanent magnet machines (IPMs). However, saturation can severely reduce field weakening performance. This is of concern in electric vehicle propulsion, where compact machines operate short-term at high power over a wide speed range. This paper shows how finite element results, including saturation, can be interpreted in established visual tools. This aids deeper understanding of field weakening in IPMs with significant saturation. Further, scaling laws for finite element results are shown to preserve field weakening performance. This allows analysis of machine peak performance over a range of maximum currents, with varying saturation severity, while scaling ensures precise fulfilment of torque and power requirements. Ultimately, this combination of current variation and scaling can be used to identify the trade-off between inverter rating and machine volume, with finite element analysis accuracy, for any specific application and IPM geometry.
23.	Jansson, Elisabet, et al. (författare) Influence of Flux Barrier Shape and Mechanical Constraints on Field-Weakening Performance in Double-Layer Interior Permanent Magnet Machines 2024 Ingår i: IEEE Transactions on Energy Conversion. - 1558-0059 .- 0885-8969. ; In Press Tidskriftsartikel (refereegranskat)abstract This paper investigates the influence of flux barrier shape on the field-weakening performance of interior permanent magnet rotors with two layers of magnets. The field-weakening performance of four topologies, with different flux barrier shape, has been maximized using combined electromagnetic and mechanical optimization of the rotor geometry. The impact of the mechanical stress constraint on the optimization result is quantified. The rotor topologies differ in both their optimal balance between saliency and normalized magnet flux linkage, and in how severely they are affected by mechanical constraints. Including stress constraints strongly increased the differences between the rotor topologies and it was shown that careful handling of the mechanical constraints was of similar importance for the field-weakening performance as the shape of the flux barrier. Among the included topologies, the double V-shape design was found to have the highest power capability across the speed range and lowest sensitivity to mechanical constraints.
24.	Jansson, Elisabet, 1989, et al. (författare) Time Resolution Dependency of Core Loss Accuracy in Finite Element Analysis of a Permanent Magnet Synchronous Machine 2020 Ingår i: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. ; , s. 1011-1017 Konferensbidrag (refereegranskat)abstract Higher time resolution in finite element analysis increases numerical accuracy, but also computational load. This paper investigates the influence of time resolution on core loss convergence, for different parts of a permanent magnet synchronous machine intended for electric vehicle propulsion. Time resolution is varied, in each of two simulated electrical periods. The core losses in the rotor parts show a slower convergence while the stator parts are more sensitive to time resolution in the first period. Finally, the trade-off between core loss accuracy and computational time is assessed. A core loss error of 1% could be reached using either 180 time steps in each electric period or, in 70% of the computational time, using 60 and 180 steps in the first and second period respectively. For the investigated case, placing 75% of the time steps in the second period gives the best compromise between computational time and core loss accuracy.
25.	Kersten, Anton, 1991, et al. (författare) Battery Loss and Stress Mitigation in a Cascaded H-Bridge Multilevel Inverter for Vehicle Traction Applications by Filter Capacitors 2019 Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 5:3, s. 659-671 Tidskriftsartikel (refereegranskat)abstract In this paper, two types of filter capacitors of varying capacity, were connected to the battery packs of a cascaded H-Bridge single-star multilevel vehicle traction inverter, and their influence on the battery losses has been analyzed. The battery and capacitor simulation models used are experimentally verified in a down-scaled system. Different capacitor configurations were simulated for four drive cycle scenarios to determine the potentials for the mitigation of current pulse stresses and battery loss reduction with respect to the added weight. By adding capacitors corresponding to a weight of 4% of the initial battery storage, the peak current is reduced by 5%-20%, depending on the operating point from DC to a few kHz, and the battery losses are reduced by 10%. In comparison, it is demonstrated that adding supercapacitors is more beneficial for lower output frequencies, while adding electrolytic capacitors is better for higher output frequencies. Furthermore, the low-order voltage harmonics of the DC-rails between the converter and battery were reduced by 10%-30% for frequencies above 9 kHz, which decreases the potential of electromagnetic disturbances. In addition, during cold battery temperatures, when it is very important to avoid heavy cyclings, the loss reduction using the capacitors was 2.5 times larger than for nominal temperature.
26.	Kersten, Anton, 1991, et al. (författare) CM & Line-Dm Noise Separation for Three-Level NPC Inverter with Connected Neutral Point for Vehicle Traction Applications 2019 Ingår i: ITEC 2019 - 2019 IEEE Transportation Electrification Conference and Expo. ; June 2019, s. 1-6 Konferensbidrag (refereegranskat)abstract EMI standards limit the noise level for conducted disturbances on DC power cables of electric vehicles. However, designing the EMI filter requires the information about the CM and DM noise levels. Therefore, a separation of the noise is needed. This paper deals with the separation and quantification of the three-phase DM and CM noise for a three-level NPC inverter with a connected neutral point. A hardware separator, based on HF transformers was developed to separate the noise into CM and line-DM noise. The CM and line-DM noise of the NPC inverter was measured, when operating the inverter with a two-level and a three-level modulation. As expected, the CM noise is dominating, and it is shown that the three-level operation reduces the noise compared to the two-level operation by about 3 to 6 dB.
27.	Kersten, Anton, 1991, et al. (författare) Efficiency of Active Three-Level and Five-Level NPC Inverters Compared to a Two-Level Inverter in a Vehicle 2018 Ingår i: 2018 20th European Conference on Power Electronics and Applications, EPE 2018 ECCE Europe. - 9789075815283 ; , s. 1-9 Konferensbidrag (refereegranskat)abstract This paper deals with a comparison of a standard two-level inverter, with a three-level and a five-level active neutral point clamped (ANPC) inverter for vehicle traction applications. The inverter efficiencies during different drive cycles are assessed and an efficiency enhancement of the multilevel inverters for partial loading and different drive cycle scenarios is found.
28.	Kersten, Anton, 1991, et al. (författare) Fault Detection and Localization for Limp Home Functionality of Three-Level NPC Inverters with Connected Neutral Point for Electric Vehicles 2019 Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 5:2, s. 416-432 Tidskriftsartikel (refereegranskat)abstract This paper deals with the detection of single battery or inverter switch faults during operation of a common and an active three-level neutral-point-clamped (NPC) inverter with a connected neutral point. Here, the main focus lies on the detection and localization of open-circuit faults of the inverter's switches. Therefore, a fault detection algorithm, using a current estimator, and two fault localization algorithms, a pulse pattern injection principle and an online adaption of the space vector modulation (SVM), are investigated and verified through simulations and experiments. Also, investigated is how the powertrain can be operated under a fault condition, so that the vehicle can drive with a limited maximum power using an adapted SVM, referred to as "limp home" mode, to the next service station. It is shown, that an active NPC inverter can cope with any single short or open-circuit fault of the inverter's switches without bringing the vehicle to standstill, whereas a generic NPC inverter loses controllability if an open-circuit fault at an inner switch occurs. Furthermore, both inverter types are able to be operated just with half of the dc-link voltage in case of a failure in one part of the battery.
29.	Kersten, Anton, 1991, et al. (författare) Inverter and Battery Drive Cycle Efficiency Comparisons of CHB and MMSP Traction Inverters for Electric Vehicles 2019 Ingår i: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe. ; , s. 1-12 Konferensbidrag (refereegranskat)abstract This paper investigates the performance of several inverter types for electric vehicles. A standard two-level and two seven-level multilevel inverters, a cascaded H-bridge (CHB) and a modular multilevel series parallel (MMSP) inverter, are considered. Based on the AC impedance spectra measured on a single battery cell, the battery pack impedances of the multilevel and two-level inverter systems are modeled. The inverter losses are modeled using the semiconductors’ datasheets. Based on the loss models, the inverter and battery efficiency during different driving cycles are assessed. In comparison to the two-level inverter system, the multilevel inverter drivetrains show an increased drivetrain efficiency, despite increased battery losses. The MMSP topology showed the best result. In comparison to the CHB topology, the battery losses were reduced by the MMSP inverter system.
30.	Lundmark, Sonja, 1966, et al. (författare) Experiences from a distance course in electric drives including on-line labs and tutorials 2012 Ingår i: 2012 20th International Conference on Electrical Machines, ICEM 2012, Marseille, 2 September - 5 September 2012. - 9781467301428 ; , s. 3050-3055 Konferensbidrag (refereegranskat)abstract This paper explains the steps taken to convert the electric drives course activities at Chalmers University of Technology to a distance course directed towards the automotive industry, including interactive remote web-labs, and on-line tutorials and computer lab sessions. A first pilot course is conducted during autumn 2011. From the course evaluation, from student results and from experience of the involved teachers during the work, it could be concluded that the first pilot course worked as planned, yielding good results in students' performance compared to the on-campus course, except for the practical lab part where students from both courses performed equally well. The web course got an average of 4.2 (out of 5.0) from the course evaluations. In order to improve the web-course, the interactivity during the practical labs should be improved.
31.	Lundmark, Sonja, 1966, et al. (författare) Heat transfer coefficients in a coupled 3-D model of a liquid-cooled IPM traction motor compared with measurements 2019 Ingår i: 2019 14th International Conference on Ecological Vehicles and Renewable Energies, EVER 2019. - 9781728137032 Konferensbidrag (refereegranskat)abstract Modelling of electrical machines is constantly refined and it is now possible to couple numerical thermal models and electromagnetic models, thereby considering the thermal effects on motor materials. In this paper it is shown how a 3-D model of an interior permanent magnet (IPM) motor, including losses in the end windings and the effect of air and liquid cooling can be made where simulation results are compared with measurements. Further, it is shown how the coolant inlet temperature and volumetric flow rate affects the heat transfer coefficient of the cooling duct for some load points within the torquespeed range of the motor.
32.	Lundmark, Sonja, 1966, et al. (författare) Heat transfer coefficients in a coupled 3-D model of a liquid-cooled IPM traction motor compared with measurements 2021 Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 57:5, s. 4805-4814 Tidskriftsartikel (refereegranskat)abstract Modelling of electrical machines is constantly refined and it is now possible to couple numerical thermal models and electromagnetic models, thereby allowing to examine the thermal effects on motor materials. In this paper it is shown how a 3-D model of an interior permanent magnet (IPM) motor, including power loss in the end windings and the effect of air and liquid cooling can be made where simulation results are compared with measurements. Further, it is shown how the coolant inlet temperature and volumetric flow rate affects the heat transfer coefficient of the cooling duct for some load points within the torque-speed range of the motor.
33.	Nordelöf, Anders, 1975, et al. (författare) A Scalable Life Cycle Inventory of an Electrical Automotive Traction Machine – Technical and Methodological Description 2016 Rapport (övrigt vetenskapligt/konstnärligt)abstract This report is one of four coupled publications. It describes the technical and methodological selections, and the data collection made to develop of a scalable life cycle inventory (LCI) model of an electrical automotive traction machine. It also presents the essential electrical machine theory background for the work. The report is intended to be used as a reference book for the scalable LCI model when detailed information and explanations are sought. Therefore, no summary or abstract has been included.The scalable LCI model covers both design and production data of a permanent magnet synchronous machine (PMSM). The resulting LCI model, in the form of a Microsoft Excel Macro-Enabled Worksheet file, can be downloaded from the Swedish Life Cycle Center as a part of the SPINE@CPM LCA Database.Furthermore, a series of two peer reviewed articles presents the LCI model based on this report. The first article, part I (DOI: 10.1007/s11367-017-1308-9), describes how the LCI model was established and the type of results it provides, including the underlying PMSM design and the structure of the LCI data model based on mainly chapters 2 and 4 of this report. Additionally to what is included here, it also contains an evaluation of the mass estimations made by the model through comparison with data for seven existing PMSMs for vehicles from established brands, published from 2013 or later.The second article, part II (DOI: 10.1007/s11367-017-1309-8), presents an overview of new primary production data and how literature data was revised to cover the complete PMSM motor manufacturing chain, including magnet fabrication, electrical steel production and a comprehensive survey of an electric motor factory. More in depth information about all production procedures, and how the data was established, is presented in Chapter 5 of this report. Part II of the article series also discusses the selected system boundaries and explains how to link the gate to gate inventory to the Ecoinvent database version 3 (Weidema et al., 2013), based on Chapter 2 of this report.
34.	Nordelöf, Anders, 1975, et al. (författare) A scalable life cycle inventory of an electrical automotive traction machine—part I: design and composition 2018 Ingår i: International Journal of Life Cycle Assessment. - : Springer Science and Business Media LLC. - 1614-7502 .- 0948-3349. ; 24:1, s. 55-69 Tidskriftsartikel (refereegranskat)abstract Purpose: A scalable life cycle inventory (LCI) model of a permanent magnet electrical machine, containing both design and production data, has been established. The purpose is to contribute with new and easy-to-use data for LCA of electric vehicles by providing a scalable mass estimation and manufacturing inventory for a typical electrical automotive traction machine. The aim of this article (part I of two publications) is to present the machine design, the model structure, and an evaluation of the models’ mass estimations. Methods: Data for design and production of electrical machines has been compiled from books, scientific papers, benchmarking literature, expert interviews, various specifications, factory records, and a factory site visit. For the design part, one small and one large reference machine were constructed in a software tool, which linked the machines’ maximum ability to deliver torque to the mass of its electromagnetically active parts. Additional data for remaining parts was then gathered separately to make the design complete. The two datasets were combined into one model, which calculates the mass of all motor subparts from an input of maximum power and torque. The range of the model is 20–200 kW and 48–477 Nm. The validity of the model was evaluated through comparison with seven permanent magnet electrical traction machines from established brands. Results and discussion: The LCI model was successfully implemented to calculate the mass content of 20 different materials in the motor. The models’ mass estimations deviate up to 21% from the examples of real motors, which still falls within expectations for a good result, considering a noticeable variability in design, even for the same machine type and similar requirements. The model results form a rough and reasonable median in comparison to the pattern created by all data points. Also, the reference motors were assessed for performance, showing that the electromagnetic efficiency reaches 96–97%. Conclusions: The LCI model relies on thorough design data collection and fundamental electromagnetic theory. The selected design has a high efficiency, and the motor is suitable for electric propulsion of vehicles. Furthermore, the LCI model generates representative mass estimations when compared with recently published data for electrical traction machines. Hence, for permanent magnet-type machines, the LCI model may be used as a generic component estimation for LCA of electric vehicles, when specific data is lacking.
35.	Nordelöf, Anders, 1975, et al. (författare) Life cycle assessment of permanent magnet electric traction motors 2019 Ingår i: Transportation Research Part D: Transport and Environment. - : Elsevier BV. - 1361-9209. ; 67, s. 263-274 Tidskriftsartikel (refereegranskat)abstract Ongoing development of electrified road vehicles entails a risk of conflict between resource issues and the reduction of greenhouse gas emissions. In this study, the environmental impact of the core design and magnet material for three electric vehicle traction motors was explored with life cycle assessment (LCA): two permanent magnet synchronous machines with neodymium-dysprosium-iron-boron or samarium-cobalt magnets, and a permanent magnet-assisted synchronous reluctance machine (PM-assisted SynRM) with strontium-ferrite magnets. These combinations of motor types and magnets, although highly relevant for vehicles, are new subjects for LCA. The study included substantial data compilation, machine design and drive-cycle calculations. All motors handle equal take-off, top speed, and driving conditions. The production (except of magnets) and use phases are modeled for two countries – Sweden and the USA – to exemplify the effects of different electricity supply. Impacts on climate change and human toxicity were found to be most important. Complete manufacturing range within 1.7–2.0 g CO2-eq./km for all options. The PM-assisted SynRM has the highest efficiency and lowest emissions of CO2. Copper production is significant for toxicity impacts and effects on human health, with problematic emissions from mining. Resource depletion results are divergent depending on evaluation method, but a sensitivity analysis proved other results to be robust. Key motor design targets are identified: high energy efficiency, slender housings, compact end-windings, segmented laminates to reduce production scrap, and easy disassembly.
36.	Rabiei, Ali, 1985, et al. (författare) Improved Maximum-Torque-Per-Ampere Algorithm Accounting for Core Saturation, Cross-Coupling Effect, and Temperature for a PMSM Intended for Vehicular Applications 2016 Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 2:2, s. 150 - 159 Tidskriftsartikel (refereegranskat)abstract This paper presents an improved method of deriving the ideal maximum-torque-per-ampere (MTPA) angle for a permanent-magnet synchronous machine (PMSM). The algorithm accounts for core saturation and cross coupling of the direct- and quadrature-axis magnetic flux. In addition, the impact of various temperatures is also investigated. The algorithm is demonstrated to provide a d{-}q current reference angle that is very close to the real MTPA-angle for the whole operating range. It is found that if the current dependency of the equivalent circuit machine parameters such L_d , L_q , and \Psi _m is updated for each optimization iteration step in an MTPA algorithm rather than being accounted for directly in the optimization, the MTPA angle is predicted up to 7° too low for the investigated machine. However, with the proposed MTPA-angle method here, this discrepancy is eliminated. Moreover, the consequence of utilizing the derived improved algorithm here is that the losses at the peak torque operating point is 6% lower than without the full optimization. This leads to an enhanced take-off ability by increasing the torque at the rated current by up to 3.6%.
37.	Theliander, Oskar, et al. (författare) Battery Modeling and Parameter Extraction for Drive Cycle Loss Evaluation of a Modular Battery System for Vehicles Based on a Cascaded H-Bridge Multilevel Inverter 2020 Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 56:6, s. 6968-6977 Tidskriftsartikel (refereegranskat)abstract This article deals with the modeling and the parameterization of the battery packs used in cascaded H-bridge multilevel propulsion inverters. Since the battery packs are intermittently conducting the motor currents, the battery cells are stressed with a dynamic current containing a substantial amount of low-order harmonic components up to a couple of kHz, which is a major difference in comparison to a traditional two-level inverter drive. Different models, such as pure resistive and dynamic RC -networks, are considered to model the energy losses for different operating points (OPs) and driving cycles. Using a small-scale setup, the models’ parameters are extracted using both a low-frequency, pulsed current, and an electrochemical impedance spectroscopy (EIS) sweep. The models are compared against measurements conducted on the small-scale setup at different OPs. Additionally, a drive cycle loss comparison is simulated. The simple resistive model overestimates the losses by about 20% and is, thus, not suitable. The dynamic three-time-constant model, parameterized by a pulsed current, complies with the measurements for all analyzed OPs, especially at low speed, with a maximum deviation of 3.8%. Extracting the parameters using an EIS seems suitable for higher speeds, though the losses for the chosen OPs are underestimated by 1.5%–7.9%.
38.	Theliander, Oskar, et al. (författare) LiFePO4 Battery Modeling and Drive Cycle Loss Evaluation in Cascaded H-Bridge Inverters for Vehicles 2019 Ingår i: ITEC 2019 - 2019 IEEE Transportation Electrification Conference and Expo. ; June 2019, s. 1-7 Konferensbidrag (refereegranskat)abstract This paper deals with the modeling and parameterization of LiFeP04batteries when used in cascaded H-bridge multilevel inverter drive systems. Since the battery packs are intermittently conducting the motor currents, the battery cells are stressed with a dynamic current waveform containing a substantial amount of low order harmonic components in the range of a couple of kHz. Different battery models like a pure resistive or different RC networks are considered, to determine the battery losses. Measurements of the voltage drop for a pulsed current of variable frequency and magnitude are done to be able to determine the model parameters. The models are then verified against measurements on a battery pack placed in a small scale multilevel inverter operated at 6 different operating point that are representative for the operation of an electrified vehicle. It is shown that the dynamic model agrees very well with the measurements for all operating points analyzed with a maximum deviation of 4 %. The results are also compared with the commonly used resistive model which overestimates the losses with typically around 20 % for the evaluated points. Simulations of 4 full drive cycles are performed where it is stated that the resistive model always shows about 20 % more losses compared to the 3 time constant model.
39.	Tidblad Lundmark, Sonja, 1966, et al. (författare) Fordonskomponenter och konfigurationer 2014 Ingår i: Perspektiv på eldrivna fordon 2014. - 9789198097443 ; , s. 10-11 Bokkapitel (övrigt vetenskapligt/konstnärligt)
40.	Tidblad Lundmark, Sonja, 1966, et al. (författare) Vehicle components and configurations 2013 Ingår i: Systems Perspectives on Electromobility 2013. - 9789198097313 ; , s. 22-32 Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract The main objective of this chapter is to describe components and configurations ofelectric drive systems used for electric or plug-in hybrid electric vehicles. Componentssuch as the battery and the battery charger are also included. The aimis to describe different alternatives, possibilities and bottlenecks associated withsuch components and configurations. We also outline some of the key factors thatinfluence automobile design.One key issue, for instance, relates to cost reduction methods, which are importantfor commercialisation. Another issue is space requirements. The way in whichcomponents are packaged within vehicles is a key design issue that relates to anefficient use of the available space.
41.	Tillman, Anne-Marie, 1958, et al. (författare) Elmaskiner för fordon i en cirkulär ekonomi. Design för miljö- och resurseffektivitet och krav på End-of-Life system. 2020 Rapport (övrigt vetenskapligt/konstnärligt)abstract Elektrifieringen av fordon drivs av nödvändigheten att drastiskt minska klimatutsläppen. Samtidigt behövs mer energi- och materialresurser för att bygga elektriska drivlinor, främst för batterier, men också för också andra komponenter i den elektriska drivlinan, som elmotorer. Föreliggande rapport fokuserar på elmotorer för framdrift av vägfordon, så kallade framdriftsmotorer, och hur de kan anpassas till den cirkulära ekonomin. Material i elmotorerna med väsentlig miljö- och resurspåverkan är aluminium, elektroplåt, koppar samt magnetmaterialen. Deras produktion kräver energi som ger upphov utsläpp av klimatpåverkande gaser. Kopparproduktion leder också till utsläpp av toxiska metaller. Koppar och magnetmetaller som kobolt och sällsynta jordartsmetaller (dit neodym och dysprosium hör) är geologiskt knappa. Gruppen sällsynta jordartsmetaller, liksom kobolt, klassas också som kritiska av EU, vilket betyder att de bedöms utgöra en försörjningsrisk samtidigt som de är ekonomiskt viktiga. Alla materialslagen ger väsentliga bidrag till materialkostnaden. Strategier för att minska resursåtgången kan vara att minimera mängden material, att byta material, att renovera och förlänga motorns livslängd, eller att återvinna motorn till högkvalitativa material. Mer cirkulära materialflöden för elfordon kräver både att fordonen och deras komponenter är utformade för lång livslängd, återanvändning och högkvalitativ återvinning, och att End-of-Life-systemet är anpassat for att effektivt ta hand om uttjänta fordon och deras komponenter och material. Projektet har därför syftat till: - Rekommendationer för design av elektriska framdriftsmotor som uppfyller krav på hög verkningsgrad och annan önskvärd teknisk prestanda, och samtidigt är lämpade för en mer cirkulär ekonomi. - Rekommendationer för utvecklingen av ett End-of-Life-system för fordon som kan nyttiggöra fordonskomponenter designade för en mer cirkulär ekonomi. Nulägesanalyser användes för att välja ett antal motoralternativ att studera, liksom olika alternativ för att hantera dem vid End-of-Life. Kravspecifikationer för studerade motorer upprättades baserat på fordonskrav för en personbil och för en buss. De mest krävande materialen identifierades, utifrån miljöpåverkan, resurstillgång på lång och kort sikt, samt kostnader. Valda motoralternativ varierade med avseende på magnetmaterial, lindningsmaterial och lindningskonfiguration. I några alternativ användes en kärna av pressat järnpulver istället för elektroplåt. Magnetflödets riktning varierade mellan de undersökta motorerna. Demonteringsstudier av använda motorer gav, tillsammans med en kartläggning av dagens End-of-Life-hantering, en beskrivning av hur uttjänta motorer hanteras idag, och utgjorde ett underlag för att ta fram ett scenario för en framtida mer cirkulär hantering med långtgående materialseparation. De utvalda motoralternativen utvärderades med hjälp av elektromagnetiska beräkningar och körscykelberäkningar som användes för att beräkna energianvändningen under drift. Denna användes i livscykelanalyser, tillsammans med data om motorernas sammansättning och produktion, för att utvärdera deras miljö- och resurspåverkan. Effekten av varierande End-of- Life-hantering undersöktes i detalj. Tre möjliga strategier för End-of-Life-systemets utveckling mot resurseffektivitet identifierades: att renovera och öka livslängden hos motorer och deras komponenter; att förbättra materialåtervinningen i dagens system med fragmentering; samt en långt driven separation av material ur motorer som demonterats ur fordonen, för materialåtervinning. Effektiviteten i användning av material och komponenter kan ökas genom renovering och återanvändning. Begränsad renoveringsverksamhet finns idag, främst för tunga fordon, men skulle kunna utökas och också omfatta lätta fordon. Delar som kan bytas ut är kullager, motoraxel och möjligen även hela rotorpaket. Rotorpaket ur kasserade motorer skulle kunna utnyttjas som reservdelar. Hela motorer ur kasserade fordon kan också återanvändas som reservdelar. Däremot är möjligheterna att återanvända magneter mycket begränsade, eftersom deras form är låst till den ursprungliga designen. I befintlig fragmenteringsverksamhet utvecklas kontinuerligt processerna för att sortera material i olika fraktioner. En utmaning för elmaskiner är de hoptrasslade nystan av koppartråd och elektroplåt som uppstår i fragmenteringen, så kallade ”köttbullar”. Separeringen av materialen i dessa skulle kunna drivas längre. Magnetmaterialen hamnar till största delen i en lättfraktion, varifrån de inte återvinns (som magnetmaterial). Inga processlösningar för återvinning av magnetmaterial ur fragmenterat skrot har identifierats. Materialåtervinningen ur framdriftsmotorer kan ökas genom att demontera motorerna ur uttjänta fordon och därefter använda semiautomatiserad separering vilket ger relativt rena materialfraktioner. Det finns utrustning på marknaden för att separera koppar, stål och aluminium från uttjänta elmotorer, En långt driven semiautomatiserad separering av dessa material förbättrar återvinningen jämfört med fragmentering, men endast i begränsad omfattning. Semiautomatiserad separering av motormaterialen är dock den enda identifierade tekniken som gör det möjligt att återvinna magnetmaterial med såpass kvalitet att de kan användas för nytillverkning av magneter. Det finns ingen kommersiell utrustning för att separera ut magneter ur elmotorer inför återvinning idag, men det har gjorts experimentellt, och det finns processlösningar på prototypstadiet. Renovering av framdriftsmotorer kräver att de enkelt kan demonteras ur fordonet och att motorn sedan utan svårigheter kan demonteras till en nivå där delar kan bytas ut. Fixerings- och impregneringsmedel bör därför användas på ett genomtänkt sätt och antalet varianter av skruvar och andra fästanordningar minimeras. Motorns design är avgörande för både dess klimatpåverkan och resursanvändning. Klimatpåverkan orsakas av energianvändningen under drift, som avgörs av verkningsgraden över körcykeln och motorns vikt. Designval med betydelse är valet av lindningsmaterial och lindningskonfiguration. Koppar ger högre energieffektivitet än aluminium, liksom designer med hög andel koppar i det aktiva tvärsnittet, som hårnålslindning eller koncentrerad lindning. De svaga magneter av strontium-ferrit som undersöktes gav låg energianvändning över körcykeln. Strontium-ferritmagneter är dock inte stabila vid temperaturer under cirka 20oC, vilket är en teknisk utmaning som måste lösas. En intressant utvecklingsmöjlighet är att eftersträva elmotorer med hög effekttäthet, till exempel genom att de designas med mer koppar i spåren, kombinerat med svaga magneter. Ett färre antal starka magneter är också en möjlighet. Designer med kärna av pressat järnpulver ger ingen fördel i materialåtervinningen, eftersom dagens fragmenteringsprocesser återvinner koppar, stål och aluminium med tämligen hög effektivitet. Magnetmaterialen återvinns dock inte och inga designåtgärder i elmotor-utvecklingen har identifierats som kan möjliggöra magnetåtervinning i fragmenterings-processen. Däremot, semiautomatiserad demontering av magneter skulle underlättas av en långt driven standardisering av laminatets tvärsnitt, liksom av att magneterna inte limmas fast.
42.	Xun, Qian, 1990, et al. (författare) Drive Cycle Energy Efficiency of Fuel Cell/Supercapacitor Passive Hybrid Vehicle System 2021 Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 57:1, s. 894-903 Tidskriftsartikel (refereegranskat)abstract The electric vehicle with passive hybridization of fuel cells and supercapacitors leads to lower cost and compactness due to the absence of DC/DC converters. This paper models such a vehicle and evaluates the energy efficiency of its powertrain system. The powertrain component losses, as functions of electric machine torque, speed and DC-link voltage, are modelled with a high level of detail which are verified against available test data. Compared to a pure fuel cell system, the fuel cell efficiency is higher when supercapacitors are introduced under pulse current load, and it is higher at lower current amplitude. As the pulse current frequency increases, the fuel cell efficiency also increases due to higher proportional current from the high-efficiency supercapacitors. A multiplicity of drive cycles is selected, divided into a low, middle, and high speed category to analyze the powertrain efficiency. The total powertrain energy efficiency varies between 53%-71% during propulsion for the studied drive cycles, whereas it is higher during braking ranging from 84% to 94%. The differences are closely related to the speed, acceleration, and DC-link voltage levels. The lower powertrain efficiency causes higher hydrogen consumption, leading to a reduced fuel cell efficiency at high speed, high acceleration and low DC-link voltage.
43.	Xun, Qian, 1990, et al. (författare) Modelling and simulation of fuel cell/ supercapacitor passive hybrid vehicle system 2019 Ingår i: 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019. ; , s. 2690-2696 Konferensbidrag (refereegranskat)abstract The concept of the passive hybrid system is to develop a single-stage power conversion topology in which fuel cell and supercapacitor can be directly coupled, leading to low cost and compactness in the absence of DC/DC converters. The paper deals with the modelling and simulation of such a vehicle system. The powertrain component losses are modelled with a high level of detail, and they are functions of speed, torque and DC-link voltage. Different drive cycles divided into a low, middle, and high-speed category are used to evaluate the performance of the powertrain system. The wheel energy per distance and powertrain efficiency differs between the drive cycles due to the different speed and acceleration levels. Furthermore, the acceleration and WLTC characteristics of the powertrain system show that in the passive hybrid system, the supercapacitors can support fuel cells as a low-pass filter. As a result, the peak power requirement can be successfully achieved due to the lowered system impedance, and the fuel cell only needs to supply the average power during operation. © 2019 IEEE.

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