Change search
Refine search result
1 - 39 of 39
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Alahakoon, Sanath
    et al.
    Central Queensland University, Australia.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Emerging energy storage solutions for transportation - A review: An insight into road, rail, sea and air transportation applications2015In: Electrical Systems for Aircraft, Railway and Ship Propulsion, ESARS, IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    Increasing usage of hybrid electric vehicles, plug-in electric vehicles and emerging new concepts in transportation such as electric highways have raised the significant role of energy storage solutions for transportation to its highest level. It is impossible to specify a single energy storage solution that can satisfactorily fulfill the varying performance demands of various applications in transportation. This paper will identify some of the most demanded performance requirements from some of the key applications in transportation and assess the suitability of emerging energy storage solutions against those.

  • 2.
    Alahakoon, Sanath
    et al.
    Cent Queensland Univ, Sch Engn & Technol, Ft Wayne, IN 4680 USA. eksell, Mats; Ostlund, Stefan.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Östlund, Stefan
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Emerging Energy Storage Solutions for Transportation Electrification - A view2019In: International Journal of Engineering and Technology Innovation, ISSN 2223-5329, E-ISSN 2226-809X, Vol. 9, no 2, p. 75-90Article, review/survey (Refereed)
    Abstract [en]

    Energy storages have caught the attention of transportation community r the past several years. Rsecent developments in hybrid and plug-in ectric vehicles together with novel concepts in transportation such as ectric highways are the reasons for raising the role of energy orages in transportation to such a significant level. Performance mands for energy storage solutions vary significantly from one ansportation application to the other, making it difficult for the ientific community to converge to a single energy storage solution at caters all. This paper reviews the key performance demands of the jor transportation applications. It also investigates the aracteristics of emerging energy storage solutions and assess their itability for those reviewed transportation applications.

  • 3.
    Bessman, Alexander
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Soares, Rúdi Cavalerio
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Svens, P.
    Investigating the aging effect of current ripple on lithium-ion cells2015In: ECS Transactions, Electrochemical Society, 2015, Vol. 69, no 18, p. 101-106Conference paper (Refereed)
    Abstract [en]

    We have built an experimental setup which exposes twelve cells to a well-defined ripple current. It consists of a system for cycling high capacity cells in parallel with a triangular current waveform superimposed on top of the direct current. The frequency of the waveform is variable up to 50 Hz, and the sum of the DC and AC components can have a magnitude of -40 A to 40 A. Current is measured over a 500 μω shunt resistor. The voltage and current of each cell is read simultaneously at a sample rate up to 4 MS/s, allowing for precise impedance measurements even for high frequency harmonics. The cells are cycled at 40 °C. The experiment has been designed to eliminate indirect effects of the AC harmonics as far as possible. This system is being used to test whether or not AC harmonics affect Li-ion aging.

  • 4.
    Cosic, Alija
    et al.
    KTH, Superseded Departments, Electrical Systems.
    Lindbäck, Jens
    Arshad, Waqas Mahmood
    KTH, Superseded Departments, Electrical Systems.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES).
    Thelin, Peter
    Nordlund, Erik
    APPLICATION OF A FREE-PISTON GENERATOR IN A SERIES HYBRID VEHICLE2003In: Proceedings of the 4th international Symposium on Linear Drives for Industry Applications, 2003, p. 541-544Conference paper (Refereed)
    Abstract [en]

    This paper deals with an investigation of differentcontrol strategies for a series hybrid electric vehicle (SHEV).Another discussed issue is the application of a free-pistongenerator. By replacing a conventional combustion enginewith a free-piston generator it is possible to increase the totalefficiency of the system. The object of investigation is a12-ton truck, mainly used in urban areas. The drive systemhas been built up and simulated in a MATLAB Simulinkenvironment. It follows from the investigation that theapplication of a free-piston engine in a SEHV can increasethe efficiency by 25 percent compared to the conventionalengine.

  • 5.
    Cosic, Alija
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    3D Analyses of a Novel Transverse Flux Machine for a Free Piston Energy Converter2009In: ICEM: 2008 INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES, NEW YORK: IEEE , 2009, p. 324-329Conference paper (Refereed)
    Abstract [en]

    The electrical machine is one of the key parts in the Free Piston Energy Converter (FPEC), and as such the electrical machine faces very tough requirements such as low weight of the translator and high power density. During the design process great emphasis has been put not only on the machine performance but also on the manufacturing process. This paper investigates a novel Transverse Flux Linear machine for the FPEC application. At first, the analytical calculations are performed based on some estimation of the leakage flux in the machine. However, during the FEM analysis and measurements it was obvious that a more detailed analysis was required in order to achieve a better agreement in results. A more detailed reluctance network is developed and used for the analysis. The results are compared with both FEM simulations and the measurements.

  • 6. Hagbin, Saeid
    et al.
    Alukula, Mats
    Khan, Kashif
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Lundmark, Sonja
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Carlson, Ola
    An integrated charger for plug-in hybrid electric vehicles based on a special interior permanent magnet motor2010Conference paper (Refereed)
    Abstract [en]

    For a plug-in hybrid electric vehicle (PHEV), the battery needs to be charged from the grid while the vehicle is parked. The traction system components are normally not engaged during the charging time so there is a possibility to use them in the charger system to develop an integrated charger. An innovative high power isolated three-phase bi-directional integrated charger with unit power factor operation is introduced for PHEVs based on a special configuration of the ac motor. The winding of the machine is re-arranged in charging mode to have a three-phase boost based high power battery charger. The system configuration, the device model (machine with multiple windings), traction and charging system functionality and charger control are presented in this paper.

  • 7. Hagbin, Saeid
    et al.
    Khan, Kashif
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Lundmark, Sonja
    Alukula, Mats
    Carlson, Ola
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Integrated chargers for EV's and PHEV's: Examples and new solutions2010Conference paper (Refereed)
    Abstract [en]

    The battery is an important component in an electric vehicle (EV) or a plug-in hybrid electric vehicle (PHEV) and it should be charged from the grid in a cost efficient, preferably fast and definitely safe way. The charger could be an on board or an off board charger. For an on board charger it is possible to use available hardware of the traction system, mainly the inverter and the electric motor, in the charger circuit. This is called an integrated charger. In this paper, different examples of integrated chargers are reviewed and explained. Additionally, other possible solutions of integrated chargers are described.

  • 8.
    Hansson, Jörgen
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Performance of a Series Hybrid Electric Vehicle with a Free-Piston Energy Converter2006In: 2006 IEEE VEHICLE POWER AND PROPULSION CONFERENCE, NEW YORK, NY: IEEE , 2006, p. 108-113Conference paper (Refereed)
    Abstract [en]

    The free-piston energy converter (FPEC), consists of an internal combustion engine and a linear electrical machine. It is characterised by high efficiency and rapid transient response, which makes it suitable for hybrid electric vehicles. In this paper we investigate the performance gain of utilising the FPEC in a medium sized series hybrid electric vehicle (SHEV), compared to a conventional diesel-generator. First, we utilise optimisation to find a lower limit on the SHEVs fuel consumption for a given drive cycle. In addition, we develop a control strategy based on the ideas of an equivalent consumption minimisation (ECM) proposed earlier in the literature. The results show a potential decrease in fuel consumption of up to 19% compared to a diesel-generator SHEV. The ECM control strategy behaves as desired, and a 13% reduction of fuel consumption compared to a traditional load-following strategy is achieved.

  • 9.
    Hansson, Jörgen
    et al.
    KTH, School of Electrical Engineering (EES).
    Leksell, Mats
    KTH, School of Electrical Engineering (EES).
    Carlsson, Fredrik
    KTH, School of Electrical Engineering (EES).
    Minimizing power pulsations in a free piston energy converter2005In: 2005 European Conference on Power Electronics and Applications, 2005Conference paper (Refereed)
    Abstract [en]

    A Free Piston Energy Converter (FPEC) is a combination of a linear combustion engine and a linear electrical machine. This type of converter has many potential advantages like high efficiency, low fuel consumption and low emissions, which make it suitable for a series hybrid vehicle. However, the generated power pulsates due to the reciprocating motion of the translator. This paper presents a comparative study on how different generator force profiles affect the electric power pulsations produced by the FPEC. In addition, the influence of these profiles on translator motion and the needed power converter current is investigated. A dynamic free piston model is used for the investigation. Results show that the generator force profile has a major impact on the power pulsation amplitude and peak current demand. Thus the chosen force profile will affect dimensioning of power converter, electrical machine and energy storage. Furthermore, loading the translator heavily in the beginning or end of the stroke seems to affect the peak translator velocity more than evenly distributed load profiles.

  • 10.
    Hansson, Jörgen
    et al.
    KTH, School of Electrical Engineering (EES).
    Leksell, Mats
    KTH, School of Electrical Engineering (EES).
    Carlsson, Fredrik
    KTH, School of Electrical Engineering (EES).
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES).
    Operational strategies for a free piston energy converter2005In: Proceedings of the Fifth International Symposium on Linear Drives for Industry Applications (LDIA05), 2005Conference paper (Refereed)
    Abstract [en]

    This paper investigates how the losses in a Free Piston Energy Converter during start, stop and idling affects energy consumption and required power from the supply system. Simulation results indicate that the electrical machine efficiency is the most critical factor during start. Moreover, by choosing the correct amplitude of the starting force, energy consumption during start can be reduced. When it comes to idling, friction is the most significant loss factor. Nevertheless, by compensating the mechanical loss for short time intervals using the generator force, the reciprocating motion can be kept alive for a rapid start without major energy consumption.

  • 11. Jansson, Magnus
    et al.
    Harnefors, L.
    Wallmark, Oskar
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Synchronization at startup and stable rotation reversal of sensorless nonsalient PMSM drives2006In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 53, no 2, p. 379-387Article in journal (Refereed)
    Abstract [en]

    In this paper, a variant of the well-known voltage model is applied to rotor position estimation for sensorless control of nonsalient permanent-magnet synchronous motors (PMSMs). Particular focus is on a low-speed operation. It is shown that a guaranteed synchronization from any initial rotor position and stable reversal of rotation can be accomplished, in both cases under load. Stable rotation reversal is accomplished by making the estimator insensitive to the stator resistance. It is also shown that the closed-loop speed dynamics are similar to those of a sensored drive for speeds above approximately 0.1 per unit, provided that the model stator inductance is underestimated. Experimental results support the theory.

  • 12.
    Khan, Kashif
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Haghbin, Saeid
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Design and performance analysis of a permanent-magnet assisted synchronous reluctance machine for an integrated charger application2010In: 19th International Conference on Electrical Machines, ICEM 2010, 2010, p. 5607905-Conference paper (Refereed)
    Abstract [en]

    In a plug-in hybrid electric vehicle equipped with an integrated charger, the electric machine and the inverter, which in traction mode are used to propel the vehicle and recover energy during braking, are also used to charge the battery from the grid while the vehicle is at rest [1]. This paper studies the design and performance of a permanent-magnet assisted synchronous reluctance machine (PMaSynRM) both in traction and charging mode. Designing a PMaSynRM in order to obtain optimal reluctance and magnetic torque components is a complex task since rotor dimensioning for one torque component (magnet or reluctance torque) limits the possibility to optimize the other torque component. This paper identifies and relates the design parameters that influence these torque components and the performance of the machine using simulations based on the finite element method. The results are compared based on developed torque, torque ripple and relative values of the resulting magnet and reluctance torque.

  • 13.
    Khan, Kashif
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Design aspects on magnet placement in permanent-magnet assisted synchronous reluctance machines2010In: IET Conference Publications, Institution of Engineering and Technology, 2010Conference paper (Refereed)
    Abstract [en]

    The design of permanent-magnet assisted synchronous reluctance machines (PMRSMs) for optimum reluctance and magnetic torque components is a complex task since rotor dimensioning for one torque component (magnet or reluctance torque) limits the possibility to optimize the other torque component. This paper identifies and relates the design parameters that influence these torque components. It describes the influence of insulation ratio, magnet size and magnet placement on the performance of the machine using finite element (FEM) based simulations. The results are compared based on developed torque, torque ripple and relative values of the resulting magnet and reluctance torque.

  • 14.
    Leksell, Mats
    et al.
    KTH, Superseded Departments, Electrical Systems.
    Harnefors, Lennart
    Malardalen University, Sweden.
    Jansson, Magnus
    Direct Sensorless Speed Control of PM-Motors - a simple and effective sensorless method2001In: 32nd Annual Power Electronics Specialists Conference, IEEE , 2001, Vol. 2, p. 805-810Conference paper (Refereed)
    Abstract [en]

    This paper presents a method for sensorless speed control of non-salient permanent magnet synchronous motors (PMSM). Special attention is put on the startup and synchronization of the motor, which are crucial for good performance of the drive system. The method merges both estimation and control of speed into one combined algorithm. Good performance is verified theoretically and experimentally.

  • 15.
    Leksell, Mats
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Harnefors, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Machine Design Considerations for Sensorless Control of PM Motors1998In: Proc. of the International Conference on Electrical Machines 1998, 1998Conference paper (Refereed)
  • 16.
    Nategh, Shafigh
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Huang, Zhe
    Krings, Andreas
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Thermal Modeling of Directly Cooled Electric Machines Using Lumped Parameter and Limited CFD Analysis2013In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 28, no 4, p. 979-990Article in journal (Refereed)
    Abstract [en]

    This paper presents a practical approach to model thermal effects in directly cooled electric machines. The main focus is put on modeling the heat transfer in the stator winding and to the cooling system, which are the two critical parts of the studied machines from a thermal point of view. A multisegment structure is proposed that divides the stator, winding, and cooling system into a number of angular segments. Thereby, the circumferential temperature variation due to the nonuniform distribution of the coolant in the cooling channels can be predicted. Additionally, partial computational fluid dynamics (CFD) simulations are carried out to model the coolant flow in the cooling channels and also on the outer surface of the end winding bodies. The CFD simulation results are used as input to the analytical models describing the convective heat transfer to the coolant. The modeling approach is attractive due to its simplicity since CFD simulations of the complete machine are avoided. The proposed thermal model is evaluated experimentally on two directly cooled induction machines where the stator winding is impregnated using varnish and epoxy, respectively. A good correspondence between the predicted and measured temperatures under different cooling conditions and loss levels is obtained.

  • 17.
    Nategh, Shafigh
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Huang, Zhe
    Lunds tekniska högskola.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Krings, Andreas
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Thermal Modeling of Directry Cooled Electric Machenes Using Lumped Parameter and Limited CFD AnalysisArticle in journal (Other academic)
  • 18.
    Nategh, Shafigh
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Krings, Andreas
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Huang, Zhe
    Lunds tekniska högskola.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Lindenmo, Magnus
    Evaluation of stator and rotor lamination materials for thermal management of a PMaSRM2012In: Proceedings of the 20th International Conference on Electrical Machines, ICEM 2012, 2012, p. 1309-1314Conference paper (Refereed)
    Abstract [en]

    In this paper, the thermal impact of using different steel laminations in the stator and the rotor of a permanentmagnet assisted synchronous reluctance machine designed for an automotive application is studied. In this regard, two main parameters of the steel lamination materials, thickness and amount of alloy content in weight percent, are studied. Frequency characteristics of the iron losses of the studied materials are used to estimate iron losses in the stator and rotor laminations. An accurate lumped parameter model including a housing water jacket cooling system is used to model thermal effects and estimate the temperature distribution in critical parts of the machine. The predicted temperature distributions in the machines show that using lamination materials with different amounts of alloy content leads to 2%-10% variation in the temperatures of rotor and winding. However, using materials with different thicknesses results in substantial temperature changes in critical parts of the machine (up to 75%).

  • 19.
    Nategh, Shafigh
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Krings, Andreas
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Evaluation of Impregnation Materials for Thermal Management of Liquid-Cooled Electric Machines2014In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 61, no 11, p. 5956-5965Article in journal (Refereed)
    Abstract [en]

    In this paper, the thermal impact of using different impregnation materials on high-performance liquid-cooled electric machines is studied. In this regard, varnish, Epoxylite, and a silicone-based thermally conductive material are considered. To study thermal effects of using different impregnation materials in theory, an advanced lumped-parameter thermal model of the studied electric machines is developed. In addition to the simulation studies, three identical induction machines using the aforementioned materials are manufactured and evaluated. Experimental tests are carried out at a wide range of current magnitudes and cooling conditions. A good agreement between the temperature measurements and corresponding simulation results is observed. It is demonstrated that using innovative thermally conductive materials in the stator slots and the end winding bodies of liquid-cooled electric machines results in a significant reduction in the winding hot spot temperature. Additionally, the influence of the critical parameters on the impregnation material performance, e. g., impregnation goodness and slot fill factor, is studied.

  • 20. Nategh, Shafigh
    et al.
    Lassila, Viktor
    Huang, Zhe
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Evaluation of alternative stator and rotor lamination materials for thermal management of permanent magnet machines2011Conference paper (Refereed)
  • 21.
    Nategh, Shafigh
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Thermal analysis of permanent-magnet synchronous reluctance machines2011In: 14th European Conference on Power Electronics and Applications, 2011Conference paper (Refereed)
    Abstract [en]

    This paper presents a thermal analysis of permanent-magnet synchronous reluctance machines (PM-SRM). Particular focus is put on the rotor and two lumped parameter (LP) thermal models of the rotor are implemented and evaluated. The results of the two LP thermal models are compared to thermal simulations using the finite element method (FEM). Induced eddy current losses in the permanent magnets are computed using three-dimensional (3D) FEM computations whereas the losses in the electrical steel are obtained using a 2D FEM model. Based on type of cooling system, two cases are evaluated and the agreement between the two LP thermal simulations and the thermal FEM simulation is generally good but particular differences are highlighted. In the first case, the water cooling system manages to effectively handle the dominating copper losses which results in only a minor temperature difference between the shaft and the inner part of the stator teeth. In the second case, it is assumed that there is a significant temperature difference between the rotor shaft and the stator.

  • 22.
    Nategh, Shafigh
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Zhao, Shuang
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Thermal Analysis of a PMaSRM Using Partial FEA and Lumped Parameter Modeling2012In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 27, no 2, p. 477-488Article in journal (Refereed)
    Abstract [en]

    This paper presents an advanced lumped parameter (LP) thermal model for a permanent-magnet assisted synchronous reluctance machine (PMaSRM) developed for propulsion in a hybrid electric vehicle. Particular focus is put on the stator winding and a thermal model is proposed that divides the stator slot into a number of elliptical copper and impregnation layers. The model is enabled by the derivation of an approximate analytical expression for the thermal resistance of an elliptical cylinder with constant thickness. The approach is attractive due to its simplicity and the fact that it closely models the actual temperature distribution for common slot geometries. Additionally, an analysis, using results from a proposed simplified thermal finite element model representing only one slot of the stator and its corresponding end winding, is presented in which the number of layers and the proper connection between the parts of the LP thermal model representing the end winding and the active part of winding is determined. The presented thermal model is evaluated experimentally on a PMaSRM equipped with a water cooling jacket, and a good correspondence between the predicted and measured temperatures is obtained.

  • 23.
    Nikouie Harnefors, Mojgan
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Jin, Lebing
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Harnefors, Lennart
    ABB Corporate Research, Västerås, Sweden.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Analysis of the dc-link stability for the stacked polyphase bridges converter2015In: 2015 17th European Conference on Power Electronics and Applications (EPE'15 ECCE-Europe), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    This paper presents an analysis of the capacitor voltage stability for a stacked polyphase bridges (SPB)

    type converter. The SPB converter comprises of several submodules which are connected in series.

    Therefore, stability of the dc-link voltage is very important to investigate. From the analysis, a corresponding

    controller and an analytical expression for stability are derived. The proposed controller and

    the associated stability condition are verified in a simulation environment and on a small experimental

    setup.

  • 24. Pietiläinen, K. D.
    et al.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Voltage sag ride-through for active rectifiers2005In: Proceedings of the Eighth IASTED International Conference on Power and Energy Systems, ACTA Press, 2005, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this paper we design a converter control for voltage sag ride-through with good load disturbance rejection. The algorithm is intended to improve the performance of the standard industrial motor drive with intermediate dc-voltage link. There are four options for ride-through, dependent on the strength of the supply grid. A further improvement of the ride-through has been achieved by also considering the driven load.

  • 25.
    Samaranayake, Lilantha
    et al.
    KTH, Superseded Departments, Electrical Systems.
    Alahakoon, Sanath
    KTH, Superseded Departments, Electrical Systems.
    Leksell, Mats
    KTH, Superseded Departments, Electrical Systems.
    Control and Scheduling Co-design of Distributed Real-Time Control Systems2004Conference paper (Refereed)
    Abstract [en]

    Closing control loops over networks is becomingincreasingly popular in embedded applications because of itsflexibility, but it also introduces many new problems. From acontrol perspective, the computer system will introduce (possiblyrandom) delays in the control loop. There is also the potentialproblem of lost measurement signals or control signals. Froma real-time perspective, the first problem is figuring out thetemporal constraints (deadlines, etc.) of the different tasks in thesystem, and then scheduling the CPUs and the network such thatall constraints are met during runtime. As a recurring example,a DC servo, whose position control-loop that is closed over aSwitched Ethernet communication network is studied. It is thenextended to three such systems running parallel sharing the CPUtime and the network bandwidth. Hence different schedulingpolicies with subtask scheduling is investigated.

  • 26.
    Samaranayake, Lilantha
    et al.
    KTH, Superseded Departments, Electrical Systems.
    Leksell, Mats
    KTH, Superseded Departments, Electrical Systems.
    Output feedback predictor compensating time-delays in distributed real-time systems2004In: Proceedings of the Sixth IASTED International Conference on Intelligent Systems and Control / [ed] Hamza, MH, CALGARY: ACTA PRESS , 2004, p. 162-167Conference paper (Refereed)
    Abstract [en]

    Inherent time-delays in distributed real-time control systems can deorade the performance or unstable the system unless treated properly. Standard delay compensation schemes usually include time stamped measurements, which require clock synchronization at different nodes. This needs periodic re-synchronization to minimize the impact of clock drift. consuming additional bandwidth. Further, the controller to actuator delay is unknown prior to the controller calculation, where probability distribution based complicated methods are required, to know it in advance. In this paper, a plant model based predictor is cascaded to the state observer to predict the states corresponding to the next sample. These states are then used in the controller to derive the next control signal, which is released C just after reading the next sample. This completely eliminates clock synchronization and complications in delay compensation. The proposed method is implemented in simulation in a real-time environment for open loop stable and unstable systems.

  • 27.
    Samaranayake, Lilantha
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Alahakoon, S
    Distributed control of an XY board via Ethernet2005In: Proceedings of the Eighth IASTED International Conference on Intelligent Systems and Control, CALGARY: ACTA PRESS , 2005, p. 216-221Conference paper (Refereed)
    Abstract [en]

    With the recent IPv6, Power over Ethernet (PoE) and robust hardware designs, Switched Ethernet technology is currently reaching the status of a complete fieldbus system for harsh factory floor applications. However, the investors still hesitate on its field level operation for time critical applications, due to the non-deterministic delays in the closed world of a switched network. The objective of this paper is to practically prove an adaptive sampling scheme to handle network delays and to highlight the potential of Switched Ethernet in implementing time critical real-time distributed control system applications. Experiments are carried out on a distributed XY board, in which the speed and position control loops on each axis, are closed through a 100Mbps Switched Ethernet network.

  • 28. Samaranayake, Lilantha
    et al.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Alahakoon, S
    Relating sampling period and control delay in distributed control systems2005In: Eurocon 2005: The International Conference on Computer as a Tool, Vol 1 and 2 , Proceedings, NEW YORK: IEEE , 2005, p. 274-277Conference paper (Other academic)
    Abstract [en]

    The control delay in distributed control systems may be compensated on-line or off-line depending on the required quality of the output, available computational power of the controller node, time stamping and clock synchronizing facilities etc. Irrespective of the compensation technique, there is an upper bound to the constant or variable control delay, which is decided by the plant, controller and the selected sampling period of the distributed computer controlled system. It is shown that in general, if the control delay exceeds the sampling period, the system becomes multi-rate; deteriorate performance as the plant updates do not correspond to the output samples. This paper introduces an adaptive sampling scheme to ensure the control delay is less than the sampling period in steady state and uses the maximum tolerable delay of the system at a particular sampling interval to ensure stable transform from one sampling period to another.

  • 29.
    Samaranayake, Lilantha
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Vijayananda, T
    Alahakoon, S
    Ethernet ready sensor actuator module for distributed control applications2005In: Eurocon 2005: The International Conference on Computer as a Tool, Vol 1 and 2 , Proceedings, NEW YORK: IEEE , 2005, p. 342-345Conference paper (Refereed)
    Abstract [en]

    Ethernet today is the most widely used information carrier and the service provider for many important applications in the routine life such as e-mail, voice-image data and web based information. It is also emerging strongly into the area of industrial communication covering even sensors and actuators at the factory floor level. However, obtaining network connectivity for existing machinery is still an open question on which many research interests are being focused. This paper presents the hardware development of a general purpose Ethernet Ready Sensor Actuator (ERSA) module and its usage in closing the speed control loop of a Brushless DC motor over a standard Switched Ethernet network. The module is subsequently used to compare connection oriented TCP with connectionless UDP for the same Distributed Control Application under constant network traffic but at different sampling rates.

  • 30.
    Soares, Rudi
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Bessman, Alexander
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Svens, Pontus
    Design Aspects of an Experimental Setup for Investigating Current Ripple Effects in Lithium-ion Battery Cells2015In: Power Electronics and Applications (EPE'15 ECCE-Europe), 2015 17th European Conference on, IEEE conference proceedings, 2015, p. 1-8Conference paper (Refereed)
    Abstract [en]

    This paper describes an experimental setup for investigating the effects of current ripple on lithium-ion battery cells. The experimental setup is designed so that twelve li-ion cells can be simultaneously tested in a controlled environment. The experimental setup allows for a wide range of current ripple in terms of frequency and amplitude. Additionally, the quantification of the current ripple effects such as the aging of li-ion cells implies that a precise measurement system has to be designed which also are discussed in the paper.

  • 31.
    Zhang, Hui
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    An iterative FEA-based approach for the design of fault-tolerant IPM-FSCW machines2015In: 2015 17TH EUROPEAN CONFERENCE ON POWER ELECTRONICS AND APPLICATIONS (EPE'15 ECCE-EUROPE), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    This paper presents an iterative finite-element analysis (FEA) approach for the design of integrated electric drives comprising of interior permanent magnet fractional-slot concentrated winding (IPM-FSCW) machines and the stacked poly-phase bridges (SPB) converter. Particular focus is put on fault tolerance to handle a shorted converter submodule and the level of fault tolerance versus compactness (torque density) and power factor is quantified in the form of a case study considering a 30 kW, 2000 rpm machine.

  • 32.
    Zhang, Hui
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    On fault tolerance for IPM-FSCW machines adopting a modular converter2014In: 2014 17th International Conference on Electrical Machines and Systems, ICEMS 2014, 2014, p. 1633-1638Conference paper (Refereed)
    Abstract [en]

    This paper investigates the fault-tolerant capability of a number of 30 kW permanent magnet (PM) machines with fractional-slot concentrated windings (FSCWs) when connected to two types of modular type converters recently proposed in the literature. Due to the strong PM rotor magnetization when using NdFeB-type magnets, the resulting short-circuit currents during a converter submodule short-circuit was found to be larger than the rated current which, potentially, may cause the machine to overheat. Reducing the PM rotor magnetization will reduce the short-circuit current but also affect the constant power speed range (CPSR). The results further highlight the importance of a tailored design specification when designing FSCW PM machines in automotive applications.

  • 33.
    Zhang, Hui
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Harnefors, Mojgan
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Jin, Lebing
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Machine design considerations for an MHF/SPB-converter based electric drive2014In: 2014 The 40th Annual Conference of the IEEE Industrial Electronics Society, IECON 2014, 2014, p. 3849-3854Conference paper (Refereed)
    Abstract [en]

    This paper identifies suitable phase/slot/pole combinationsfor fractional-slot concentrated winding (FSCW)permanent-magnet machines when forming an integrated electricdrive together with a modular high frequency (MHF) converteror a stacked polyphase bridge (SPB) converter.

  • 34.
    Zhao, Shuang
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Haghbin, S.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Lundmark, S.
    Carlson, O.
    Transient modeling of an integrated charger for a plug-in hybrid electric vehicle2011In: Proceedings of the 2011 14th European Conference on Power Electronics and Applications, EPE 2011, IEEE conference proceedings, 2011, p. 1-10Conference paper (Refereed)
    Abstract [en]

    This paper considers a permanent magnet assisted synchronous reluctance (PMSynRel) machine for an integrated charger application for use in a plug-in hybrid electric vehicle (PHEV). The integrated charger functionality means that the machine is also used when the battery is charged from the electrical grid. A finite element model (FEM) is presented from which a transient model of the complete system is derived. The resulting model can be used for simulating and tuning the algorithms needed to synchronize the machine to the electrical grid and controlling the charging process.

  • 35.
    Zhao, Shuang
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Lasson, Anders
    Volvo Cars AB.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Off-Vehicle Evaluation of Active Oscillation Damping Schemes2014In: IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN 2168-6777, Vol. 2, no 2, p. 264-271Article in journal (Refereed)
    Abstract [en]

    Torsional drivetrain oscillations are a well-known problem in electrical or hybrid electric drivetrains and may greatly influence the driving comfort. An experimental testing setup that can be used to design and evaluate active oscillation damping schemes is proposed in this paper. Instead of an in-vehicle test, the drivetrain transmission is emulated from mathematic models, executed by a servo drive which is connected to the physical electrical drive system. The proposed setup functions as a hardware-in-the-loop simulator and can be easily adjusted to simulate any drive trains without additional cost.

  • 36.
    Zhao, Shuang
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Analysis of a deeply saturated sensorless PMSynRel drive for an automotive application2011In: Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011), IEEE conference proceedings, 2011, p. 1-10Conference paper (Refereed)
    Abstract [en]

    This paper presents an method of mapping feasible region for a sensorless control PMSynRel drive using the resulting position error signal. Thanks to the rotor anisotropy, the rotor position can be detected at low speeds by means of injecting high frequency voltage, either a pulsating voltage vector in the estimated synchronous frame or a rotating vector in the stator frame, on top of the fundamental excitation. However, the resulting position error signal is degraded and distorted by magnetic saturation (including crosssaturation) and spatial inductance harmonics. Therefore, the feasible region is used to find the stable operating points. Instead of mapping the inductances, which is time consuming, position error signal is used to map the feasible sensorless control region. A prediction method of the maximum position estimation error is also presented by taking the spatial inductance harmonics into account. After that, some techniques are presented to compensate the cross-saturation and slot harmonic effects in order to improve the sensorless control quality. Additionally, it is shown how saturation in the rotor bridges affects the initial polarity detection required during startup.

  • 37.
    Zhao, Shuang
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Damping of Torsional Drive-Train Oscillationsusing a Position Sensorless PMSynRel DriveIn: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059Article in journal (Other academic)
  • 38.
    Zhao, Shuang
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Low-Speed Sensorless Control With Reduced Copper Losses for Saturated PMSynRel Machines2013In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 28, no 4, p. 841-848Article in journal (Refereed)
    Abstract [en]

    Permanent-magnet-assisted synchronous reluctance (PMSynRel) machines are generally well suited for sensorless operation at all speeds since the rotor topology possesses a magnetic saliency. However, magnetic saturation can result in a vanishing differential saliency which renders sensorless control at certain operating points difficult (or even impossible) at low speed. In this paper, an optimization procedure, based on results from finite-element (FEM)-based simulations, is proposed. As output, current reference trajectories are obtained in which copper losses are kept at minimum, while the capability for sensorless control is still maintained. The results from the FEM-based simulations are in good agreement with the corresponding experimental results. For the experimental prototype in consideration, the torque limit when operating sensorless at low speed is increased substantially from below 45% to around 95% of its rated value with only slightly increased copper losses. Additionally, the impact of position-dependent harmonics on the magnetic cross saturation (affecting the steady-state position estimation error) is found to be substantial. This highlights that this spatial variation should be taken into consideration for accurate prediction of performance during sensorless operation even if the winding of the machine is of the conventional distributed type.

  • 39.
    Zhao, Shuang
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Leksell, Mats
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Lasson, Anders
    Off-Vehicle Evaluation of Active Oscillation Damping Schemes2013In: 2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013, 2013Conference paper (Refereed)
    Abstract [en]

    Torsional drivetrains oscillations is a well known problem in electrical or hybrid electric drivetrains which may greatly influence the driving comfort. An experimental testing setup that can be used to design and evaluate active oscillation damping schemes is proposed in this paper. Instead of in-vehicle test, the drivetrain transmission is emulated from mathematic models, executed by a servo drive which is connected to the physical electrical drive system. The proposed setup functions as a hardware-in-the-loop simulator and can be easily adjusted to simulate any drivetrains without additional cost.

1 - 39 of 39
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf