Search results for: Nenad Mijatovic

Items from 1 to 20 out of 26 results

article

Nonlinear Dynamic Model of PMBLDC Motor Considering Core Losses

Muhammed Fasil, Nenad Mijatovic, Bogi Bech Jensen, Joachim Holboll

IEEE Transactions on Industrial Electronics > 2017 > 64 > 12 > 9282 - 9290

The phase variable model is used commonly when simulating a motor drive system with a three-phase permanent magnet brushless dc (PMBLDC) motor. The phase variable model neglects core losses and this affects its accuracy when modeling fractional-slot machines. The inaccuracy of phase variable model of fractional-slot machines can be attributed to considerable armature flux harmonics, which causes an...

article

Residual signal feature extraction for gearbox planetary stage fault detection

Georgios Alexandros Skrimpas, Thomas Ursin, Christian Sweeney, Kun Marhadi, more

Wind Energy > 20 > 8 > 1389 - 1404

Faults in planetary gears and related bearings, e.g. planet bearings and planet carrier bearings, pose inherent difficulties on their accurate and consistent detection associated mainly to the low energy in slow rotating stages and the operating complexity of planetary gearboxes. In this work, statistical features measuring the signal energy and Gaussianity are calculated from the residual signals...

article

A Full-Size High-Temperature Superconducting Coil Employed in a Wind Turbine Generator Setup

Xiaowei Song, Nenad Mijatovic, Jurgen Kellers, Carsten Buhrer, more

IEEE Transactions on Applied Superconductivity > 2017 > 27 > 4-2 > 1 - 5

A full-size stationary experimental setup, which is a pole pair segment of a 2 MW high-temperature superconducting (HTS) wind turbine generator, has been built and tested under the HTS-GEN project in Denmark. The performance of the HTS coil is crucial to the setup, and further to the development of the full generator. This paper deals with the HTS coil employed in the setup. The coil utilizing YBCO...

article

A Pole Pair Segment of a 2-MW High-Temperature Superconducting Wind Turbine Generator

Xiaowei Song, Nenad Mijatovic, Jurgen Kellers, Carsten Buhrer, more

IEEE Transactions on Applied Superconductivity > 2017 > 27 > 4-2 > 1 - 5

A 2-MW high-temperature superconducting (HTS) generator with 24 pole pairs has been designed for the wind turbine application. In order to identify potential challenges and obtain practical knowledge prior to production, a full-size stationary experimental setup, which is one pole pair segment of the full generator, has been built and tested. The experimental setup comprises a consequent-pole HTS...

article

Short Circuits of a 10-MW High-Temperature Superconducting Wind Turbine Generator

Xiaowei Song, Dong Liu, Henk Polinder, Nenad Mijatovic, more

IEEE Transactions on Applied Superconductivity > 2017 > 27 > 4-2 > 1 - 5

Direct Drive high-temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits take place at generator terminals. In this paper, a finite element model that couples magnetic fields and the...

article

Direct Reuse of Rare Earth Permanent Magnets—Coating Integrity

Stig Hogberg, Joachim Holboll, Nenad Mijatovic, Bogi Bech Jensen, more

IEEE Transactions on Magnetics > 2017 > 53 > 4-2 > 1 - 9

Rare earth permanent magnets can be reused directly as an alternative to traditional recycling methods, in which scrapped magnets are reprocessed into new magnets by undergoing many of the original energy-intensive and expensive production processes. Direct reuse entails using segmented magnet assemblies built by several small standard-sized magnets that can be reused directly in a number of different...

chapter

Axial permanent magnet generator for wearable energy harvesting

Stig Hogberg, Jakob Sodahl, Nenad Mijatovic, Johan Pedersen, more

2016 XXII International Conference on Electrical Machines (ICEM) > 677 - 682

2016 XXII International Conference on Electrical Machines (ICEM)

An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable application. The design was approached from an electromagnetic point of view in this article. Two types of axial...

chapter

Direct reuse of rare earth permanent magnets — Wind turbine generator case study

Stig Hogberg, Thomas Stigsberg Pedersen, Flemming Buus Bendixen, Nenad Mijatovic, more

2016 XXII International Conference on Electrical Machines (ICEM) > 1625 - 1629

2016 XXII International Conference on Electrical Machines (ICEM)

A novel recycling strategy, direct reuse, for rare earth permanent magnets were investigated in this article. Direct reuse uses small, unit-cell (segmented) magnets to replace the normal solid pole configuration, which is not directly reusable due its unique shape and size. The unit-cell magnets are directly reusable due to their standard shape and size, and direct reuse effectively bypasses a number...

chapter

Topology optimisation of PMSM rotor for pump application

Alexander Niels August Hermann, Nenad Mijatovic, Matthew Lee Henriksen

2016 XXII International Conference on Electrical Machines (ICEM) > 2119 - 2125

2016 XXII International Conference on Electrical Machines (ICEM)

This paper proposes a design optimization procedure of a PMSM rotor. In the process of optimization, the shape and the size of the permanent magnet is considered constant while the distribution of electric steel and voids (air) in the rotor are variables contributing to the final objective. For the gradient search the “Method of Moving Asymptotes” algorithm is applied to the rotor design of an internal...

chapter

A 3.0MW case study of the influence of PM cost on wind turbine cost of energy

Matthew L. Henriksen, Bogi B. Jensen, Nenad Mijatovic, Joachim Holboll

2016 IEEE Energy Conversion Congress and Exposition (ECCE) > 1 - 8

2016 IEEE Energy Conversion Congress and Exposition (ECCE)

A wind turbine generator optimization procedure based on minimization of annual energy losses and drivetrain cost is presented. Pareto fronts for four different 3.0MW wind turbine drivetrains utilizing permanent magnet synchronous machines are presented. The results are given for three different scenarios in which the magnet cost is varied. This variation affects direct-drive machines the most. A...

article

AC Losses and Their Thermal Effect in High-Temperature Superconducting Machines

Xiaowei Song, Nenad Mijatovic, Shengnan Zou, Bogi Bech Jensen, more

IEEE Transactions on Applied Superconductivity > 2016 > 26 > 4 > 1 - 5

In transient operations or fault conditions, high-temperature superconducting (HTS) machines suffer ac losses, which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate ac losses and their thermal effect in HTS machines is presented. The method consists of three submodels that are coupled only in one direction. The magnetic field distribution...

article

Performance Variation of Ferrite Magnet PMBLDC Motor With Temperature

Muhammed Fasil, Nenad Mijatovic, Bogi Bech Jensen, Joachim Holboll

IEEE Transactions on Magnetics > 2015 > 51 > 12 > 1 - 6

The price fluctuations of rare-earth (RE) metals and the uncertainty in their availability have generated an increased interest in ferrite magnet machines. The influence of temperature on the

$B$

–

$H$

characteristics of the ferrite magnet differs considerably from that of the RE magnet, and hence, requires a different approach when deciding their operating point. In this paper, the laboratory measured...

chapter

Detection of generator bearing inner race creep by means of vibration and temperature analysis

Georgios A. Skrimpas, Ivaylo G. Dragiev, Reynir Hilmisson, Christian W. Sweeney, more

2015 IEEE 10th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) > 303 - 309

2015 IEEE 10th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED)

Vibration and temperature analysis are the two dominating condition monitoring techniques applied to fault detection of bearing failures in wind turbine generators. Relative movement between the bearing inner ring and generator axle is one of the most severe failure modes in terms of secondary damages and development. Detection of bearing creep can be achieved reliably based on continuous trending...

article

Employment of Kernel Methods on Wind Turbine Power Performance Assessment

Georgios Alexandros Skrimpas, Christian Walsted Sweeney, Kun S. Marhadi, Bogi Bech Jensen, more

IEEE Transactions on Sustainable Energy > 2015 > 6 > 3 > 698 - 706

A power performance assessment technique is developed for the detection of power production discrepancies in wind turbines. The method employs a widely used nonparametric pattern recognition technique, the kernel methods. The evaluation is based on the trending of an extracted feature from the kernel matrix, called similarity index, which is introduced by the authors for the first time. The operation...

article

Design Study of Fully Superconducting Wind Turbine Generators

Xiaowei Song, Nenad Mijatovic, Bogi Bech Jensen, Joachim Holboll

IEEE Transactions on Applied Superconductivity > 2015 > 25 > 3-2 > 1 - 5

In this paper, two fully superconducting generators employing MgB₂ armature winding, with YBCO and MgB ₂ field winding respectively, are presented and analyzed. The ac loss in armature winding is estimated, and a simple comparative study is carried out. The results show that both electromagnetic designs for fully superconducting generators are promising with respect to the power density. However,...

chapter

Influence of demagnetization-temperature on magnetic performance of recycled Nd-Fe-B magnets

Stig Hogberg, Flemming Buus Bendixen, Nenad Mijatovic, Bogi Bech Jensen, more

2015 IEEE International Electric Machines & Drives Conference (IEMDC) > 1242 - 1246

2015 IEEE International Electric Machines & Drives Conference (IEMDC)

Recycling rare earth permanent magnets is becoming an important alternative source of supply of raw materials for neodymium-iron-boron (Nd-Fe-B) permanent magnets. This article documents a recycling case-study in which isotropic binder-free magnet powder is extracted and recycled from hermetically-sealed rotors. The extraction process is detailed, and the influence of demagnetization-temperature on...

chapter

Structural design of SynRM rotor, and the effect on power factor

Matthew L. Henriksen, Bogi B. Jensen, Nenad Mijatovic, Jere Kolehmainen, more

2015 IEEE International Electric Machines & Drives Conference (IEMDC) > 516 - 522

2015 IEEE International Electric Machines & Drives Conference (IEMDC)

In this paper, structural designs for multiple synchoronous reluctance machine (SynRM) rotor configurations are presented. The rotor flux bridges are increased in thickness until mechanical integrity is achieved, and then the performance of the resulting SynRM is observed. After performing this analysis for SynRM rotors with different barrier numbers and different flux bridge configurations, this...

chapter

Parametric design optimization of a novel permanent magnet coupling using finite element analysis

Stig Hogberg, Nenad Mijatovic, Joachim Holboll, Bogi Bech Jensen, more

2014 IEEE Energy Conversion Congress and Exposition (ECCE) > 1465 - 1471

2014 IEEE Energy Conversion Congress and Exposition (ECCE)

A parametric design optimization routine has been applied to a novel magnetic coupling with improved recyclability. Coupling designs are modeled in a 3-D finite element environment, and evaluated by three design objectives: pull-out torque, torque density by magnet mass, and torque density by total mass. Magnet and outer core thicknesses are varied discretely, whereas outer dimensions and air-gap...

chapter

Analysis of generator bearing vibration data for diagnosing rotor circuit malfunction in DFIGs

Georgios A. Skrimpas, Christian W. Sweeney, Bogi B. Jensen, Nenad Mijatovic, more

2014 International Conference on Electrical Machines (ICEM) > 1746 - 1751

2014 XXI International Conference on Electrical Machines (ICEM)

Doubly fed induction generators (DFIGs) are the most popular configuration met in the wind energy sector occupying approximately 65% of the total market share. Condition monitoring of wind turbine generators is performed based on vibration data collected from accelerometers mounted on the drive end and non-drive end bearings, meeting the requirements of numerous turbine operators for condition based...

chapter

Parallel Hierarchical Affinity Propagation with MapReduce

Dillon Mark Rose, Jean Michel Rouly, Rana Haber, Nenad Mijatovic, more

2014 IEEE International Conference on Cloud Engineering > 367 - 372

2014 IEEE International Conference on Cloud Engineering (IC2E)

The accelerated evolution and explosion of the Internet and social media is generating voluminous quantities of data (on zettabyte scales). Paramount amongst the desires to manipulate and extract actionable intelligence from vast big data volumes is the need for scalable, performance-conscious analytics algorithms. To directly address this need, we propose a novel MapReduce implementation of the exemplar-based...

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INFONA - science communication portal

Search results for: Nenad Mijatovic

Nonlinear Dynamic Model of PMBLDC Motor Considering Core Losses

Residual signal feature extraction for gearbox planetary stage fault detection

A Full-Size High-Temperature Superconducting Coil Employed in a Wind Turbine Generator Setup

A Pole Pair Segment of a 2-MW High-Temperature Superconducting Wind Turbine Generator

Short Circuits of a 10-MW High-Temperature Superconducting Wind Turbine Generator

Direct Reuse of Rare Earth Permanent Magnets—Coating Integrity

Axial permanent magnet generator for wearable energy harvesting

Direct reuse of rare earth permanent magnets — Wind turbine generator case study

Topology optimisation of PMSM rotor for pump application

A 3.0MW case study of the influence of PM cost on wind turbine cost of energy

AC Losses and Their Thermal Effect in High-Temperature Superconducting Machines

Performance Variation of Ferrite Magnet PMBLDC Motor With Temperature

Detection of generator bearing inner race creep by means of vibration and temperature analysis

Employment of Kernel Methods on Wind Turbine Power Performance Assessment

Design Study of Fully Superconducting Wind Turbine Generators

Influence of demagnetization-temperature on magnetic performance of recycled Nd-Fe-B magnets

Structural design of SynRM rotor, and the effect on power factor

Parametric design optimization of a novel permanent magnet coupling using finite element analysis

Analysis of generator bearing vibration data for diagnosing rotor circuit malfunction in DFIGs

Parallel Hierarchical Affinity Propagation with MapReduce

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