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Dynamic and Steady-State 3-D Thermal Design and Investigation of the Rotating Power Electronic IGBT Converter
KTH, School of Electrical Engineering (EES), Electrical Energy Conversion. (Electrical Machines and Drives)ORCID iD: 0000-0002-4694-802X
KTH, School of Electrical Engineering (EES), Communication Theory. NCSU, FREEDM Systems Center, Raliegh, USA.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

This paper deals with a 3-dimensional developmentof a thermal model of a power electronic converter mountedon the generator shaft and rotating with it. The dimensions ofthe heat sink are determined and the temperature gradients ofthe converter, its heat sink, and shaft during natural and forcedconvection are analyzed for variable rotor speeds. It is shown thatthe chosen sizes of the IGBT and heat sink offers compact designof the rotating converter, which is sufficient for its mounting inthe limited space, offered by the generator shaft. Furthermore,transient temperature profile is also presented. Additionally,transient thermal profile of the converter and dimensions of thecooling fan are also calculated. Besides analysis of the coolingrequirements of the converter during over-currents due to gridfaults is also investigated.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering
URN: urn:nbn:se:kth:diva-174339OAI: diva2:858983

QS 2015

Available from: 2015-10-05 Created: 2015-10-05 Last updated: 2015-10-06Bibliographically approved
In thesis
1. Modelling, Analysis, and Control Aspects of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator
Open this publication in new window or tab >>Modelling, Analysis, and Control Aspects of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the modeling, analysis and control of a novel brushlessgenerator for wind power application. The generator is named as rotatingpower electronic brushless doubly-fed induction machine/generator (RPEBDFIM/G).

A great advantage of the RPE-BDFIG is that the slip power recoveryis realized in a brushless manner. This is achieved by introducing an additionalmachine termed as exciter together with the rotating power electronicconverters, which are mounted on the shaft of a DFIG. It is shown that theexciter recovers the slip power in a mechanical manner, and delivers it backto the grid. As a result, slip rings and carbon brushes can be eliminated,increasing the robustness of the system, and reducing the maintenance costsand down-time of the turbine.

To begin with, the dynamic model of the RPE-BDFIG is developed andanalyzed. Using the dynamic model, the working principle of the generatoris understood and its operation explained. The analysis is carried out atspeeds, ±20% around the synchronous speed of the generator. Moreover, thedynamics of the generator due to external load-torque disturbances are investigated.Additionally, the steady-state model is also derived and analyzed forthe machine, when operating in motor mode.

As a next step, the closed-loop control of the generator is considered indetail. The power and speed control of the two machines of the generator andthe dc-link voltage control is designed using internal model control (IMC)principles. It is found that it is possible to maintain the stability of thegenerator against load-torque disturbances from the turbine and the exciter,at the same time maintain a constant dc-link voltage of the rotor converter.The closed-loop control is also implemented and the operation of the generatorwith the control theory is confirmed through experiments.In the third part of the thesis, the impact of grid faults on the behaviourof the generator is investigated. The operation of the generator and its responseis studied during symmetrical and unsymmetrical faults. An approachto successful ride through of the symmetrical faults is presented, using passiveresistive network (PRN). Moreover, in order to limit the electrical and mechanicaloscillations in the generator during unsymmetrical faults, the dualvector control (DVC) is implemented. It is found that DVC to a certain extentcan be used to safeguard the converter against large oscillations in rotorcurrents.

Finally, for completeness of the thesis, a preliminary physical design ofthe rotating power electronic converter has been done in a finite elementsoftware called ANSYS. The thermal footprint and the cooling capability,with estimates of the heatsink and fan sizes, are presented.

Besides, another variant of a rotating electronic induction machine whichis based on the Lindmark concept and operating in a single-fed mode is also investigated. It’s steady-state model is developed and verified through experiments.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xi, 85 p.
TRITA-EE, ISSN 1653-5146 ; 2015:63
Brushless doubly-fed induction generator, dual vector control, dynamic model, induction machine, internal model control, Lindmark concept, low-voltage ride-through, passive resistive network, rotating power electronic converter, rotating exciter, symmetrical faults, synchronous machine, thermal model, unity power factor, unsymmetrical faults, vector control, wind turbines.
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Electrical Engineering; Energy Technology
urn:nbn:se:kth:diva-174349 (URN)978-91-7595-691-6 (ISBN)
Public defence
2015-10-19, F3, Lindstedtsvägen 26, KTH, Stockholm, 20:23 (English)

QC 20151006

Available from: 2015-10-06 Created: 2015-10-05 Last updated: 2015-10-06Bibliographically approved

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