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  • 1.
    Hu, Yifei
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Cosic, A.
    Östlund, Stefan
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Zhang, Hui
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Design and optimization procedure of a single-sided linear induction motor applied to an Articulated funiculator2016In: 2016 IEEE 8th International Power Electronics and Motion Control Conference, IPEMC-ECCE Asia 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 3096-3102, article id 7512790Conference paper (Refereed)
    Abstract [en]

    The paper describes the design of a single-sided linear induction motor (SLIM) intended for an Articulated Funiculator (AF). A procedure is proposed where first an analytical design is carried out to obtain a preliminary geometry. The analytical design is based on approximate equivalent circuits under constrained conditions. In the second step a two-dimensional finite element method (2D-FEM) analysis is performed to validate the accuracy of the analytical models. The modification and optimization are conducted to acquire the best design.

  • 2.
    Hui, Zhang
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Limitations and constraints of eddy-current loss models for interior permanent-magnet motors with fractional-slot concentrated windings2017In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 3Article in journal (Refereed)
    Abstract [en]

    This paper analyzes and compares models for predicting average magnet losses in interior permanent-magnet motors with fractional-slot concentrated windings due to harmonics in the armature reaction (assuming sinusoidal phase currents). Particularly, loss models adopting different formulations and solutions to the Helmholtz equation to solve for the eddy currents are compared to a simpler model relying on an assumed eddy-current distribution. Boundaries in terms of magnet dimensions and angular frequency are identified (numerically and using an identified approximate analytical expression) to aid the machine designer whether the more simple loss model is applicable or not. The assumption of a uniform flux-density variation (used in the loss models) is also investigated for the case of V-shaped and straight interior permanent magnets. Finally, predicted volumetric loss densities are exemplified for combinations of slot and pole numbers common in automotive applications.

  • 3.
    Jin, Lebing
    et al.
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Zhang, Hui
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Evaluation of a Multiphase Drive System in EV and HEV Applications2015In: 2015 IEEE INTERNATIONAL ELECTRIC MACHINES & DRIVES CONFERENCE (IEMDC), Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 941-945Conference paper (Refereed)
    Abstract [en]

    Multiphase machine drive systems have been applied in many electric propulsion fields such as aerospace and electric vehicle applications. With the development of SiC semiconductors, its superior characteristic makes compact multiphase converters possible. Moreover, by using a single chip in each switch, problems caused by an uneven current split between paralleled devices can be avoided. This paper presents a performance evaluation for a 50 kW multiphase EV/HEV drive system with 1.2 kV SiC MOSFETs. Power loss calculation, cost comparison and system simulation are provided to illustrate the feasibility of the proposed concept.

  • 4.
    Jin, Lebing
    et al.
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Zhang, Hui
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Comparison and Evaluation of Modular Integrated Electric Drives for Automotive Traction ApplicationsIn: IEEE Transactions on Transportation Electrification, ISSN 2332-7782Article in journal (Refereed)
    Abstract [en]

    In order to increase the competitiveness of the integrated motor drives (IMDs), alternative topologies have been developed for electric and hybrid electric vehicles. Within this framework, the integrated modular motor drive (IMMD) concept has been proposed, aiming to make the system more compact and fault-tolerant. Potential converter topologies for an IMMD are reviewed in this paper, with particular focus on the stacked polyphase bridges converter, the parallel-connected polyphase bridges converter and the modular high frequency converter. The machine topologies that are the best candidates to be used in such drive systems are also presented. Based on the FreedomCar 2020 specifications, a comparative evaluation of the studied topologies is presented and discussed in terms of machine design, power losses, energy storage requirements, and cell redundancy. The conventional two-level three-phase drive system is utilized as the reference. Finally, predicted costs of the studied drive systems are compared for both fault-tolerant designs and non-fault tolerant designs.

  • 5. Nategh, Shafigh
    et al.
    Zhang, Hui
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Aldo, Boglietti
    Nassen, Tobias
    Bombardier Transportat, SE-72214 Vasteras, Sweden.
    Bazant, Martin
    Bombardier Transportat, CH-8050 Zurich, Switzerland.
    Transient thermal modeling and analysis of railway traction motors2018In: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 66, no 1, p. 79-89, article id 8328892Article in journal (Refereed)
    Abstract [en]

    This paper presents a practical approach to modeland analyze transient thermal effects in open air-cooled electrictraction motors. The developed thermal modeling method enablesaccurate estimation of temperature in critical parts of the motorincluding winding and bearing. Advantages of both numericaland analytical modelling methods are exploited with the aim ofrealizing accurate estimation of hot spot temperatures in tractionmotors while keeping the computation time within a reasonablerange. Computational fluid dynamics (CFD) simulations arecarried out to model the cooling fan’s performance and airflow distribution in the motor in order to provide heat transferboundary inputs to the developed combined finite element (FE)and lumped parameter (LP) thermal model. The combinationof the FE and LP models keeps the size of the model relativelysmall and enables running transient calculations reasonably fast.Also, the developed model provides the possibility to studythe influence of stator and rotor duct blockages on the motorthermal performance which is a common root of failure intraction applications during operation in dirty environments. Theproposed thermal model is verified using experimental results ona traction motor equipped with temperature sensors in motorcritical parts and a good agreement between estimated andmeasured temperatures is achieved. Finally, a calibrated fullyanalytical model using the abovementioned developed model isimplemented to further reduce simulation running time andcalculate motor temperature under normal running condition.

  • 6.
    Nikouie, Mojgan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Zhang, Hui
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    A highly integrated electric drive system for tomorrow's EVs and HEVs2018In: Proceedings - 2017 IEEE Southern Power Electronics Conference, SPEC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1-5Conference paper (Refereed)
    Abstract [en]

    This paper presents an ultra-compact integrated electric drive prototype. The prototype illustrates the integration of a fractional slot concentrated winding (FSCW) electric motor, a stacked polyphase bridges (SPB) converter, the control boards, and the water cooling plates into a common housing. This integrated prototype offers a high potential of compactness and cost reduction for electric and hybrid electric vehicles.

  • 7.
    Nikouie, Mojgan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Zhang, Hui
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Highly integratedelectric drives system for tomorrow’s EVs and HEVs2017Conference paper (Refereed)
    Abstract [en]

    This paper presents an ultra-compact integratedelectric drive prototype. The prototype illustrates the integrationof a fractional slot concentrated winding (FSCW) electric motor,a stacked polyphase bridges (SPB) converter, the control boards,and the water cooling plates into a common housing. Thisintegrated prototype offers a high potential of compactness andcost reduction for electric and hybrid electric vehicles.

  • 8.
    Yao, Yanmei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Sadarangani, Chandur
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Zhang, Hui
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Efficiency Improvement of a 12-Pole 17.5 kW Induction Motor Using Converter-fed Wound Rotor2017In: 2017 20TH INTERNATIONAL CONFERENCE ON ELECTRICAL MACHINES AND SYSTEMS (ICEMS), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    This paper investigates an induction machine using a novel concept of a converter-fed rotor. The stator is directly connected to the grid while the rotor is fed by a converter with a floating capacitor over the dc-link. In earlier work this topology has shown to be capable of improving the power factor and efficiency of a 4-pole induction machine. This paper explores the possibility to improve the power factor and efficiency of a squirrel-cage 12-pole 17.5 kW induction machine by redesigning the cage rotor to a wound rotor to enable connection of the rotor windings to the converter. A standard 12-pole squirrel-cage induction machine (SCIM) with an inherent low power factor is studied. A wound rotor induction machine (WRIM) is then analytically designed. The performance of the designed WRIM using the analytical model is shown to agree with the results from the finite element (FEM) simulations, thus verifying the correctness of the model. The analytical model is then further used to design different WRIMs with different dimensions and rotor slot numbers. Performances of these designed WRIMs show good potential for power factor and efficiency improvement. Particularly, an optimum efficiency improvement of 6.8%, compared with the original SCIM, has been achieved.

  • 9.
    Zhang, Hui
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    On Electric Machinery for Integrated Motor Drives in Automotive Applications2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Compact, electric drives for automotive traction applications represent animportant enabler towards realizing tomorrow’s fossil free transport solutions.One attractive solution is to integrate the power electronic converter withits associated electric machinery into a single unit. This thesis, along withits appended papers, considers design and analysis of electric machinery forintegrated electric drives intended for automotive applications. Particular focusis put on permanent-magnet synchronous machines (PMSMs) with interiormountedpermanent magnets combined with modular converter topologies.In the first part of the thesis, different converter concepts and windingarrangements suitable for an integrated drive are reviewed. Compared to theconventional solution utilizing a three-phase two-level converter, a compactintegration can be implemented by physically splitting the converter and itsassociated dc-link capacitor into a number of converter submodules. Moreover,a modular concept also enables a certain level of fault tolerance.In the second part of the thesis, fractional-slot concentrated windings(FSCWs) are analyzed. First, a review for how to determine suitable slot, pole,and phase combinations is identified considering mainly the winding factor forthe main harmonic and the associated rotor losses. Then, integrated modularconverter concepts and associated winding configurations are considered andslot, pole and phase combinations that also comply with the consideredmodular converters are proposed. Further, two possible winding arrangementssuitable for the stacked polyphase bridges (SPB) and the parallel polyphasebridges (PPB) type converter are compared with respect to torque duringpost-fault operation in the event of failure of a single converter submodule.In the third part, an iterative process adopting both finite element analysisand analytical techniques is proposed for the design of PMSMs with interiormountedpermanent magnets and FSCWs. The resulting machine designsillustrate tradeoffs in terms of fault tolerance, power factor, torque density,and potential for field-weakening operation. From a given set of specifications,an experimental prototype is also designed and built.Finally, since a FSCW generally results in a large harmonic content ofthe resulting flux-density waveform, models for predicting eddy-current lossesin the permanent magnets are analyzed and compared. Particularly, modelsadopting different formulations to the Helmholtz equation to solve for the eddycurrents are compared to a simpler model relying on an assumed eddy-currentdistribution. Boundaries in terms of magnet dimensions and angular frequencyare also identified in order to aid the machine designer whether the mostsimple loss model is applicable or not. With a prediction of the eddy-currentlosses in the permanent magnets together with a corresponding thermal model,predicted volumetric loss densities exemplified for combinations of slot andpole numbers common in automotive applications are presented along withthe associated thermal impact.

  • 10.
    Zhang, Hui
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Jin, Lebing
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Norrga, Staffan
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Evaluation of Modular Integrated Electric Drive Concepts for Automotive Traction Applications2017In: IEEE Transactions on Transportation ElectrificationArticle in journal (Other academic)
    Abstract [en]

    In order to achieve compactness and realize a certain level of fault tolerance in integrated motor drives, a number of integrated modular motor drive concepts have been proposed in recent years. In this paper, converter topology candidates suitable for an IMMD are considered with particular focus on the stacked polyphase bridges cconverter; the parallel-connected polyphase bridges converter, and the modular high frequency converter. A comparative evaluation of the studied topologies is presented and discussed in terms of machine design aspects, power losses, capacitor energy storage requirements, costs, and cell redundancy using the conventional two-level three-phase drive system as reference.

  • 11.
    Zhang, Hui
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Evaluation of winding arrangements in electric machinery for modular electric drives2016In: 2016 IEEE 8th International Power Electronics and Motion Control Conference, IPEMC-ECCE Asia 2016, IEEE conference proceedings, 2016, p. 2820-2825Conference paper (Refereed)
    Abstract [en]

    This paper considers different winding connection configurations for a modular electric drive based on series/ parallel connected polyphase bridges converter. Suitable stator winding connection configurations are identified to adapt to the converter topologies considered. Particular focus is put on the post-fault performance. Selected winding layouts are evaluated using 2D-FEM simulations.

  • 12.
    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.

  • 13.
    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.

  • 14.
    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.

1 - 14 of 14
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  • harvard1
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