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  • 1.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Analysis of a novel Transversal Flux Machine with a tubular cross-section for Free Piston Energy Converter application2010Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Constantly growing need for oil, all over the world, has caused oil price to rise rapidly during the last decade. High oil prices have made fuel economy as one of the most important factors when consumers are buying their cars today. Realizing this, many car manufacturers have developed or are looking for some alternative solutions in order to decrease fuel consumption. Combining two different technologies in a vehicle, the so called hybrid vehicle, can be seen as the first step toward a better and more sustainable development. There are several different solutions for hybrid vehicles today, among the best known are the Serie Electric Hybrid Vehicle (SEHV), the Parallel Electric Hybrid Vehicle (PEHV) and the Serie-Parallel Hybrid Electric Vehicle (SPEHV).

    By integrating a combustion engine with a linear electric machine into one unit, a system that is called Free Piston Energy Converter (FPEC) is achieved. The FPEC is suitable for use in a SEHV. Other application areas like stand alone generator are also possible.

    In this report a novel Transverse Flux Machine (TFM) with a tubular cross section of the translator has been investigated. Application of the machine in a FPEC has put tough requirement on the translator weight, specific power and force density. Different configurations of the winding arrangements as well as the magne tarrangement have been investigated. It has been concluded that the buried magnet design suffers from high leakage flux and is thus not asuitable TFM concept. Instead the surface mounted magnet design has been chosen for further investigation. An analytical model has been developed and a prototype machine has been built based on the analytical results. In order to have a better understanding of the machine characteristic a 3D-FEM analysis has been performed.

    The results from the analytical model, FEM model and measurements are analyzed and compared. The comparison between the measured and FEM-simulated results shows very good agreement. Furthermore, the results from the analytical model indicates that it can be successfully developed for further analysis and optimization of the design to give a cost-effective solution of the novel generato for mass production.

  • 2.
    Cosic, Alija
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Chandur, Sadarangani
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Cogging torque calculations for a novel concept of a Transverse Flux Linear Free-Piston Generator2007Conference paper (Refereed)
    Abstract [en]

    This paper investigates cogging force in a linear Transverse Flux Machine, TFM. 3D-FEM and 2D-FEM simulations has been performed and also two analytical methods have been applied. The analytical methods are based on the reluctant pressure method. Once the ¯eld distribution on the side of the tooth is known, the cogging force can be calculated by integrating the ¯eld. The agreement between the 2D-FEM and Conformal Mapping, CM, analytical method is good. However the 3D-FEM simulation results indicates a lower cogging force than the other two methods.

  • 3.
    Cosic, Alija
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Chandur, Sadarangani
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Fredrik, Carlsson
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    A novel concept of a Transverse Flux Linear Free-Piston Generator2005Conference paper (Refereed)
    Abstract [en]

    This paper investigates the electrical machine, which is one of the important parts in the FreePiston Energy Converter (FPEC). In the previous work it was found that one of the best candidate suitablefor the FPEC is a Transverse Flux Machine (TFM) due to the very tough requirements on the electrical ma-chine such as a low weight of the translator (movable part in the machine).This paper presents a new conceptof a linear TFM in which strong emphasis has been put to achieve a design that is simple to manufacture.Different types of the magnet confgurations on the translator have been investigated. It has been found thatthe buried magnet design suffers from a very high leakage to the nearby poles and is thus not suitable forthis type of machine. Another confguration, which has been investigated, is the surface mounted magnetconfguration. Analytical models for this confguration have been established. It has been found that thetough requirements, 4kN from a 6kg movable mass, can be achieved at the required speed, specifc powerand effciency

  • 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.
    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.
    Timmerman, Jan
    Design and manufacturing of a linear Transverse Flux Permanent Magnet Machines2008In: 2008 IEEE INDUSTRY APPLICATIONS SOCIETY ANNUAL MEETING, 2008, p. 726-730Conference paper (Refereed)
    Abstract [en]

    In general Transverse Flux Machines (TFM) are considered to be complex and difficult to manufacture. However, there are some exceptions. In the linear TFM the flux plane is the same as for the conventional rotating electrical machine. Therefore, iron laminations from conventional rotating machines can be used to manufacture the stator. The manufacturing process of the stator becomes then more simple compared to the manufacturing process of the conventional linear machine. This paper deals with a novel design of a linear TFM machine for the free piston energy converter application. It describes earlier designed and manufactured prototypes and a new manufacturing approach in order to avoid the loss in flux and thereby also loss in the force production.

  • 7.
    Cosic, Alija
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Östlund, Stefan
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Design of an Electromechanical Actuator for Active Lateral Suspension2008Report (Other academic)
  • 8.
    Cosic, Alija
    et al.
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Yao, Yanmei
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Malik, Naveed ur Rehman
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Construction of a rotating power electronic converter for induction machine operation2015Conference paper (Refereed)
    Abstract [en]

    This paper describes the construction of the rotating power electronic converter. By mounting the power electronics on the rotor of an induction machine, the rotor winding can be made easily accessible without the use of slip-rings and brushes. This offers certain advantages regarding motor control. However, it is evident that the rotating mass, communication with the converter and maintaining the mechanical stability and reliability of the system are huge challenges that must be overcome. This paper describes some solution that are partly investigated and some solutions that still needs to be investigated in more detail.

  • 9.
    Malik, Naveed ur Rehman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Synchronous Operation of a Rotating Power Electronic Brushless Doubly-Fed Generator2016In: IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 250-255, article id 7392107Conference paper (Refereed)
    Abstract [en]

    This paper presents the synchronous operation of a novel generator termed as the rotating power electronic brushless doubly-fed induction generator (RPE-BDFIG). It is shown that the generator operates well at the synchronous speed of the main machine, delivering the desired power to the grid. Furthermore, it is illustrated that the RPE-BDFIG behaves similar to a synchronous generator in the synchronous mode. The closed-loop control of the generator is implemented in real-time, and the current and voltage waveforms of the stator and rotor of the RPE-BDFIG are experimentally analyzed. The paper highlights the stable operation and full control of the generator during synchronous mode.

  • 10.
    Malik, Naveed ur Rehman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Harnefors, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion. ABB CRC Västerås.
    Experimental Validation of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator for Variable-Speed OperationManuscript (preprint) (Other academic)
    Abstract [en]

    This paper investigates through experiments a differenttopology of a brushless doubly-fed induction generatorwith a rotating power electronic converter: the rotatingpower electronic brushless doubly-fed induction generator (RPEBDFIG),operated with variable speed and torque. The theorybehind the operation of the generator is presented, its dynamicmodel and control aspects are discussed, and closed-loop controlof the generator is implemented and verified through experimentson an 11-kW prototype. The measurement results show stableoperation for variable speed and torque regions. Moreover, itis shown that the integrated rotating exciter is sufficient torecover slip power and deliver to the grid, hence, verifyingsuccessful brushless operation. Besides, it is verified that thegenerator operates well in both regions of operation, i.e., the subsynchronousand super-synchronous modes, and is stable undertorque transients added by the rotating exciter.

  • 11.
    Malik, Naveed ur Rehman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Harnefors, Lennart
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion. ABB CRC Västerås.
    Variable Reactive Power Control of a Rotating Power Electronic Brushless Doubly-Fed GeneratorManuscript (preprint) (Other academic)
    Abstract [en]

    This paper considers reactive power control of anew topology of a brushless doubly-fed generator—the rotatingpower electronic brushless doubly-fed induction generator (RPEBDFIG).It consists of a doubly-fed induction generator (DFIG),on whose rotor two power electronic converters and a rotatingexciter are mounted and rotating with its shaft. The rotatingexciter and power electronic converters supply reactive powerfrom the rotor of the DFIG, thus manipulating the powerfactor at the stator terminals. Theory for variable-reactive-poweroperation is developed and verified through experiments on an11-kW prototype.

  • 12.
    Malik, Naveed ur Rehman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Lindmark, Magnus
    Induction Machine at Unity Power Factor with Rotating Power Electronic Converter2012Conference paper (Refereed)
    Abstract [en]

    A new configuration for the self-excitation of the induction machine invented by Magnus Lindmark is presented. The power electronic converter using solid state switches is connected to the rotor while the stator is directly connected to the grid. Using appropriate control, the reactive power consumed by the motor can be generated in the rotor resulting in unity power factor operation. The rotor connected power electronic converter is also used for constant speed operation of the induction machine at variable torque.

  • 13.
    Svechkarenko, Dmitry
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Soulard, Juliette
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics.
    Transverse flux machines for sustainable development - Road transportation and power generation2007In: 2007 INTERNATIONAL CONFERENCE ON POWER ELECTRONICS AND DRIVE SYSTEMS, 2007, p. 1301-1307Conference paper (Other academic)
    Abstract [en]

    The higher specific torque and power density of a transverse flux machine (TFM) in comparison to a conventional machine makes it a promising energy converter in various applications. In this paper, a free piston energy converter and a direct-driven wind turbine are considered. The analytical investigation of the novel TFM topology applied in these two cases is presented. The cogging torque is evaluated by use of a three-dimensional finite element method. The results of simulating generators rated in the range of 3-12 MW are discussed. Manufacturing of a linear prototype is presented.

  • 14.
    YAO, YANMEI
    et al.
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Analysis of an induction machine using a rotor integrated converter with a floating capacitor2015In: Electrical Machines and Systems (ICEMS), 2015 18th International Conference on, IEEE , 2015, p. 1851-1857Conference paper (Refereed)
    Abstract [en]

    A novel topology of induction machine with a rotor integrated converter with a floating capacitor is investigated in this paper. The stator windings of the induction machine are directly connected to the grid. While the rotor windings are connected to a converter with a floating capacitor. The steady state mathematical model is presented and used to predict the operating range of the induction machine. The result shows that the induction machine can operate in a wide torque and speed range instead of working on the original torque-speed curve. In addition, the relationship between capacitance and capacitor voltage is studied for the constant speed and variable load operation. It is shown that it is possible to choose a low volume and high capacitance capacitor since the average DC-link voltage is quite low.

  • 15.
    YAO, YANMEI
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Investigation on the dynamic performance of an induction machine using a novel concept of a rotating converter with a floating capacitor2015In: Industrial Electronics Society, IECON 2015 - 41st Annual Conference of the IEEE, IEEE , 2015, p. 2944-2949Conference paper (Refereed)
    Abstract [en]

    This paper explores a topology of induction machine drive with a novel concept of a wound rotor fed by a converter with a floating DC-link capacitor. The Y-connected stator windings are connected to the grid, while Y-connected rotor windings are connected to a three phase converter with a floating DC-link capacitor. By integrating the converter into the wound rotor, the slip-rings and the brushes becomes unneeded. Constant speed operation can be achieved at various loads by controlling the fundamental frequency of the converter. The stator power factor can be effectively improved over a wide range of load at constant speed. Particularly, unity power factor can be obtained within ±25% of the rated load. Moreover, harmonic spectra of the stator and rotor currents are presented.

  • 16.
    Yao, Yanmei
    et al.
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Power Factor Improvement and Dynamic Performance of an Induction Machine With a Novel Concept of a Converter-Fed Rotor2016In: IEEE transactions on energy conversion, ISSN 0885-8969, E-ISSN 1558-0059, Vol. 31, no 2, p. 769--775Article in journal (Refereed)
    Abstract [en]

    This paper investigates an induction machine with a novel concept of the rotor fed by a converter. The stator is Y-connected and directly connected to the grid, while the rotor windings are open-ended and fed by a back-to-back converter with a floating capacitor. Power factor and efficiency improvements of the induction motor are studied with different settings of phase-shift angle between the two converters. Moreover, the dynamic performance of the induction machine is explored in MATLAB/Simulink and verified experimentally on a 1.8-kW induction machine in the laboratory. The result shows good agreement between simulation and experiment. At a constant speed, variable load operation of the induction machine is obtained by setting the frequency of the rotor voltage.

  • 17.
    Yao, Yanmei
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Cosic, Alija
    KTH, School of Electrical Engineering (EES), Electrical Energy Conversion.
    Experimental Investigation on the Speed Control and Power Factor Improvement of a Novel Induction Machine with Rotating Power Electronic Converter2013In: Proceedings of the 10th Jubilee International Symposium on Advanced Electromechanical Motion Systems: ELECTROMOTION 2013 Cluj-Napoca, Romania, October 21-22, 2013, 2013, Vol. 20, p. 138-144Conference paper (Refereed)
    Abstract [en]

    A novel speed control strategy of an inductionmachine with RPEC (rotating power electronic converter) isinvestigated in this paper. The stator of the machine is directlyconnected to the power distribution network while the open-endedrotor windings are connected to a back-to-back converter. Adynamic model is developed in the three-phase reference frame.Dynamic performance of the starting process of the system isstudied, based on an 1.8kW induction machine in the laboratory.Experimental results have shown that constant speed control isachieved in a simple manner by controlling the rotor currentfrequency. Importantly the stator power factor can be improvedeffectively within a wide range of load variation including therated load. Moreover, the dc-link voltage over the capacitorbetween the two converters is considerably low which implies agreat reduction of the capacitor size.

1 - 17 of 17
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