Analysis and design optimisation of grid-connected wound-rotor synchronous and induction motors

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Stellenbosch : Stellenbosch University
ENGLISH ABSTRACT: The dissertation presents new approaches in the analysis, design and optimisation of three-phase cylindrical wound-rotor synchronous (WRSM) and induction (WRIM) motor types. The new approaches are based on the analysis of the steady-state finite element method (FEM) in which the parameters and performances of the motor types are predicted. Absolute optimum designed WRSM and WRIM motor types can at best be obtained by the use of improved parameters and performance calculation methods in the design optimisation process. This dissertation proposes simple, fast and accurate parameter and performance calculation modern approaches for grid-connected WRSM and WRIM motor types using two-axes electromagnetic models. The modern approaches are based on non-classical models in which iterative processes are utilised using static FEM in conjunction with the motor types phasor diagrams. During the iterative processes, the electric circuit and magnetic field equations are coupled to access important parameters of the motor types. The access of parameters using iterative processes solves the excitation currents at different operating points of the motor. The parameters are accurately calculated using a FEM based method of freezing the motor core permeance. The dissertation investigates and expands the use of these parameters as an effective and powerful tool for explaining the motor behaviour under different operating points. A great deal of attention is also given to the design optimisation of the motor types during which a relatively efficient optimisation procedure is shown. In this study, the proposed model approaches are verified by employing a commercial FEM ANSYS-Maxwell and experimental tests in the laboratory. The study also gives the model approach and the design optimisation procedure of a 6 MW slip-ring motor used for milling purposes. In the analysis of this, the skin effects are perfectly fitted in the proposed model approaches The study presents a successful application of the proposed model approaches to the parameters and performance prediction and the design optimisation of the grid-connected WRSM and WRIM motor types. The proposed model approaches demonstrate accuracy, simplicity and fastness which are some of the key aspects in the electrical machine design.
AFRIKAANSE OPSOMMING: Die verhandeling stel nuwe benaderings vir die analise, ontwerp en optimering van drie-fase bewikkelderotor sinchroonmotor (WRSM) en induksiemotor (WRIM) tipes voor. Die nuwe benaderings is gebaseer op die analise van die bestendige toestand eindige element metodes (EEM) waarmee die vermo¨e van die motor tipes voorspel word. Die optimum ontwerpte WRSM en WRIM motors kan verkry word deur die gebruik van verbeterde parameter en vermo¨e berekeningmetodes in die ontwerp optimeringsproses. Hierdie verhandeling stel ‘n eenvoudige, vinnige en akkurate parameter en vermo¨e berekening vir netwerk-gekoppelde WRSM en WRIM voor deur gebruik te maak van twee-as elektromagnetiese modelle. Die moderne benaderings is gebaseer op nie-klassieke modelle waarin iteratiewe EEM in samewerking met die motor fasor diagramme gebruik word. Tydens die iteratiewe proses, word die elektriese stroombaan en magnetiese veld vergelykings gekoppel om belangrike motor parameters te kry. Die magnetiese veld vergelykings los die opweksstrome op by verskillende werkspunte van die motor. Die parameters word akkuraat bereken deur die gebruik van EEM gebaseer op die metode van die vries van die motor kern permeansies. Hierdie parameters word as ‘n effektiewe hulpmiddel gebruik om die motorgedrag by verskillende werkspunte te verduidelik. Aandag word gegee aan die motorontwerp optimering, waartydens ‘n effektiewe optimeringsproses gewys word. In die studie word die voorgestelde benaderingsmodelle deur ‘n kommersi¨ ele EEM pakket (ANSYS-Maxwell) en toetse in die laboratorium geverifieer. ‘n Benaderingsmodel en die ontwerp optimering van ‘n 6 MW sleep-ring motor vir wals toepassings word ook gegee, waar die benaderingsmodel aangepas word om huid effekte in ag te neem. Die studie wys ‘n suksesvolle toepassing van die voorgestelde benaderingsmodel vir parameter en vermo¨e voorspelling en ontwerp optimering van netwerk-gekoppelde WRSM en WRIM motor tipes. Die voorgestelde benaderingsmodel is akkuraat, vinnig en eenvoudig, wat van die sleutelaspekte in elektriese masjien ontwerp is.
Thesis (DEng)--Stellenbosch University, 2019.
Finite element method, UCTD, Electric motors, Induction, Electromagnetic measurements, Synchronous motors