Design of a field-intensified interior permanent magnet synchronous machine for electric vehicle application

Prins, Michiel Hendrik Albertus (2014-04)

Thesis (MScEng)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: The focus of this thesis is on the optimal design and evaluation of FI-PM machines to be used with a MG transmission drive-train for EV application. The machines presented are optimised using a gradient-based optimisation algorithm of the VisualDoc software together with FE software and Python scripts. Each machine is optimised for its own objective function. The focus is to reduce expensive rare earth material. High torque ripple issues of the optimised machines are solved by implementing a relatively new topology where the rotor poles/barriers are made asymmetric. The asymmetric rotor topology implemented is effective and can be used as an alternative for rotor stack skewing. PM demagnetisation and rotor deformation studies are conducted on the optimum designed machines to ensure that no PM demagnetisation on the surface of the PMs and critical rotor deformation occur. The FE performance results of the optimum designed machines are shown and discussed. One of the optimum designed FI-PM machines is manufactured and tested in the laboratory. The FE and measured results of the machine are compared and shows good correlation. The saliency performance of the optimum designed machines are evaluated as it determines its position sensorless control capability. It is shown that the saliency ratios increase linearly with load, making it favourable for position sensorless control. It is also shown that the asymmetric rotor topologies introduced a larger mutual inductance compared to their symmetric counterparts, thus higher cross-coupling is present in these rotors and therefore a higher saliency shift, which is undesirable. Two case studies are performed in order to improve saliency performance. The objective of the first case study is to improve the saliency shift by reducing the flux leakage paths in the rotor. The objective of the second case study is to optimise a FI-PM machine in order to improve the saliency ratio and -shift. The results of the two case studies are compared with the saliency performance of the other machines.

AFRIKAANSE OPSOMMING: Die fokus van hierdie tesis is op die optimale ontwerp en evaluering van veld versterking permanente magneet masjiene vir veelvoudige-rat elektriese voertuig toepassings. Die masjiene teenwoordig is geoptimeer met behulp van ’n helling-gebaseerde optimering algoritme. Elke masjien is geoptimeer vir sy eie doel funksie. Die fokus is om duur seldsame permanent magneet materiaal te verminder. Hoë wringkrag-rimpeleffek van die optimale masjiene word opgelos deur die implementering van ’n relatief nuwe topologie waar die rotor pole/vloedbarrière asimmetries gemaak word. Die asimmetriese rotor topologie wat geimplementeer is, is effektief en kan dus as ’n alternatief vir die rotor stapel skeef metode gebruik word. Permanent magneet demagnetisering en rotor vervorming studies is ook uitgevoer op die optimum ontwerpte masjiene om te verseker dat geen demagnetisering plaasvind nie en ook geen kritiese rotor vervorming nie. Die eindige-element resultate van die optimum ontwerpte masjiene word getoon en bespreek. Een van die optimum ontwerpte veld versterking permanente magneet masjiene is vervaardig en getoets in die laboratorium . Die eindige-element en gemete resultate van die masjien word vergelyk en toon goeie korrelasie. Die speek prestasie van die optimum ontwerpte masjiene word geëvalueer aangesien dit die sensorlose posisie beheer vermoë bepaal. Daar word getoon dat die speek koëffisiënt verhoog lineêr met vrag wat dit gunstig maak vir posisie sensorlose beheer . Daar word ook gewys dat die asimmetriese rotor topologie ’n groter wedersydse induktansie het in vergelyking met hul simmetriese eweknieë, dus is daar hoër kruis-koppeling teenwoordig in die rotors en dus ’n ho¨er speek skuif, wat ongewens is. Twee gevallestudies om speek prestasie te verbeter is uitgevoer. Die doel van die eerste gevallestudie is om die speek skuif te verbeter deur die vermindering van die vloed lekkasie paaie in die rotor. Die doel van die tweede gevallestudie is om ’n veld versterking permanente magneet masjiene te optimeer ten einde die speek koëffisiënt en - skuif te verbeter. Die resultate van die twee gevallestudies word vergelyk met die speek prestasie van die ander masjiene.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/86242
This item appears in the following collections: