Analytical prediction of rotor eddy current loss due to stator slotting in PM machines

Paper presented during the 2010 IEEE Conference, Electrical Machines and Systems, 2001. ICEMS 2001, Shenyang . The original publication is available at http://research.ee.sun.ac.za/emr/files/u1/2010-ECCE-Wills.pdf and also http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=971799&tag=1Wills, D. A. & Kamper, M. J.2010. Analytical prediction of rotor eddy current loss due to stator slotting in PM machines, in Electrical Machines and Systems, 2001. ICEMS 2001. Proceedings of the Fifth International Conference, 2:806 - 809, doi:10.1109/ICEMS.2001.971799.Certain types of PM electric machines are particularly susceptible to the proliferation of eddy currents flowing within the solid conducting regions in the rotor. These eddy currents can be induced by current winding harmonics, but also by the interaction of the static rotor magnetic field with the permeance variation of the slotted stator known as ‘slotting’. This work focuses on the analytical calculation of eddy current loss that occurs in the conducting regions within a rotor under no-load conditions. The results are compared with finite element analysis and measured results from a machine test. Good agreement is achieved between the three methods of comparison.Post-prin

Design optimisation of cageless flux barrier rotor reluctance synchronous machine

Dissertation (Ph. D.) -- University of Stellenbosch, 1996.Some digitised pages may appear illegible due to the condition of the original microfiche copy.ENGLISH ABSTRACT: The focus of this thesis is on the overall (stator and rotor) design optimisation of the current vector-controlled reluctance synchronous machine and the evaluation of the steady-state performance of this machine in motoring operation. The rotor considered is the cageless normal laminated flux barriertype of rotor. The absolute optimum-designed electrical machine can at best be obtained by using the finite element method in the design optimisation process. This thesis proposes a multidimensional finite element-based design optimisation method for the optimum design of the reluctance synchronous machine. The thesis stresses the explanation and understanding of the optimum-designed reluctance machine. A simple approximate magnetic circuit calculation method is used to show and explain design tendencies and to do preliminary stator design optimisations. Goodness factors for the reluctance synchronous machine are also derived. The optimised results of a number of reluctance synchronous machines that are designed according different criteria in the 3 - 10 kW power range are given and explained. A great deal of attention is also given to the performance capability of the reluctance: synchronous machine in the medium power range (sub 500 kW). The thesis shows that the proposed optimisation method can be applied with success to optimise the design of the reluctance synchronous machine. The optimum steady-state performance of the reluctance synchronous machine found in this study shows that this machine can no longer be considered as a bad machine. Although the power factor of this machine is still on the low side, the advantages of high power density and high efficiency, even in the upper-medium power range, are attractive characteristics for any variable speed drive.AFRIKAANSE OPSOMMING: Die fokus van hierdie tesis is op die totale (stator en rotor) ontwerp-optimering van die stroom vektor beheerde reluktansie sinchroonmasjien en die evaluering van die bestendige toestand vermoë van hierdie masjien in motorwerking. Die tipe rotor onder beskouing is die koulose, normaal gelamelleerde vloedbarriere tipe rotor. Die absoluut optimum ontwerpte elektriese masjien kan op sy beste verkry word deur die eindige element metode in die ontwerp-optimeringsproses te gebruik. Hierdie tesis stel 'n multidimensionele eindige element gebaseerde optimeringsmetode voor vir die optimum ontwerp van die reluktansie sinchroonmasjien. Die tesis le nadruk op die verduideliking en verstaan van die optimum ontwerpte reluktansiemasjien. 'n Eenvoudige benaderde magnetiese stroombaan berekeningsmetode is gebruik om ontwerp tendense te verduidelik en om voorlopige stator-ontwerpe te doen. Goedheidsfaktore is ook vir die reluktansie sinchroonmasjien afgelei. Die geoptimeerde resultate van 'n aantal reluktansie sinchroonmasjiene wat volgens verskillende kriteria in die 3 - 10 kW drywingsgebied ontwerp is, word gegee en verduidelik. Heelwat aandag word ook gegee aan die vermoë van die reluktansiemasjien in die medium drywingsgebied (sub 500 kW). Die tesis toon dat die voorgestelde optimeringsmetode met sukses toegepas kan word om die ontwerp van die reluktansie sinchroonmasjien te optimeer. Die optimum bestendige toestand vermoë van die reluktansie sinchroonmasjien wat in hierdie studie gevind is, toon dat die masjien nie langer meer as 'n swak masjien beskou kan word nie. Alhoewel die arbeidsfaktor van die masjien nog steeds aan die lae kant is, is die voordele van hoë drywingsdigtheid en hoë benuttingsgraad, selfs in die boonste medium drywingsgebied. aantreklike karakteristieke vir enige veranderlike spoed aandryfstelsel

Contemporary wind generators

It is believed that wind energy is growing at a very rapid rate, especially in the last few years. When compared with other sources of renewable energy in the energy portfolio, it becomes evident that the bulk is wind energy-based. However, there are some backlogs to full manifestation of this technology ranging from initial high cost to performance and reliability issues, among others. But in spite of these bottlenecks, new research trends have been assertive in seeking out a sustainable solution for harnessing wind energy for power generation – especially in the design and construction of wind generators. In order to motivate and prime a sustainable energy mix among stakeholders, this paper is a shot at appraising the theory of these innovative wind generators towards ecological sustainability, economy, efficiency, and employment creation

Potentials of locally manufactured wound-field flux switching wind generator in South Africa

The China-based monopoly of high-energy permanent magnet materials used in modern wind generators impact the economic viability and local content value of most wind turbines installed in South Africa, especially large installations. It is possible to design with less expensive excitation technologies using locally-sourced wound-field electromagnets, which might promote local content. This study involves the optimum design performance comparison of the wound-field flux switching machine (WF-FSM) technology based on two variants – Design I and II (D-I and D-II) – the difference being in the arrangement of their DC wound-field coils. The machines are evaluated using finite element analyses (FEA) with optimum performance emphasised on design parameters such as torque density, efficiency and power factor. The selected design targets are meant to improve the performance to cost fidelity of the proposed wind generator variants. In 2D FEA, D-II can produce up to 18.8% higher torque density (kNm/m3) and 17.1% lesser loss per active volume (kW/m3) than D-I. In 3D FEA, the torque density of D-II remains higher at 10.6%, but its loss per active volume increases by 15% compared to D-I. The discrepancy observed in 2D and 3D FEA is due to an underestimation of the end-winding effects in D-II. The power factor of D-II is higher than D-I, both in 2D and 3D FEA, which may translate to lower kVA ratings and inverter costs. A higher total active mass ensues for the studied WF-FSMs than a conventional direct-drive PMSG, but avoiding rare earth PMs translate to significantly lower costs

Die ontwerp-kriteria en ontwikkeling van 'n ontwerpprogram vir kourotor-induksiemotors vir gebruik in die belastingsgebied

Proefskrif (M.Ing.) -- Universiteit van Stellenbosch, 1987.Full text to be digitised and attached to bibliographic record

On the Design and Topology Selection of Permanent Magnet Synchronous Generators for Natural Impedance Matching in Small-Scale Uncontrolled Passive Wind Generator Systems

Small-scale uncontrolled passive wind generator systems are an attractive solution for rural energy generation because of the system’s reliability and low cost. However, designing these uncontrolled wind generators for good power matching with the wind turbine is challenging and often requires external impedance matching. In this paper, permanent magnet generators with different stator and rotor structures were investigated and designed to increase the generator’s synchronous inductance for a natural impedance matching. For the design methodology, multi-objective optimisation was used to design the generators for near-maximum turbine power matching, whereby internal impedance matching was reached as much as possible. It was shown that altering the placement and orientation of the permanent magnets in the rotor is a viable method to achieve the desired impedance matching; however, these generators do not have the best performance. It was found that the surface-mounted permanent magnet generator with semi-closed slots was the optimum topology. An optimised generator prototype was tested for the experimental validation. All designs were verified by comparing the results of 2D and 3D finite-element analysis

Wind generator impedance matching in small-scale passive wind energy systems

CITATION: Labuschagne, C. J. J. & Kamper, M. J. 2021. Wind generator impedance matching in small-scale passive wind energy systems. IEEE Access, 9:22558-22568, doi:10.1109/ACCESS.2021.3056226.The original publication is available at https://ieeexplore.ieee.orgENGLISH ABSTRACT: In this paper, the improved turbine power matching of passive wind energy systems for dcconnected battery storage applications with an impedance matching method is investigated. The passive system uses a direct-drive permanent magnet synchronous generator and is directly connected via a diode recti er to the dc xed-voltage battery storage. To improve power matching, an external inductance is added to the passive system between the generator and the diode recti er. A static nite element based solution method is proposed to accurately calculate the necessary external inductance to achieve near maximum power point matching. It is shown that the proposed nite element based calculation method is computationally ef cient and excellently suited for generator design optimization, which is critical for this application. It is also shown that by rewinding existing machines for the correct cut-in speed and adding the external inductance for improved power matching, existing machines can be effectively recycled for passive wind energy systems. The proposed static nite element solution method's accuracy and improved power matching are con rmed with measured results on a sub 5 kW power level.https://ieeexplore.ieee.org/document/9343816Publisher's versio

Contemporary wind generators

CITATION: Akuru, U. B. & Kamper, M. J. 2015. Contemporary wind generators. Journal of Energy in Southern Africa, 26(3):116-124.The original publication is available at http://www.scielo.org.zaIt is believed that wind energy is growing at a very rapid rate, especially in the last few years. When compared with other sources of renewable energy in the energy portfolio, it becomes evident that the bulk is wind energy-based. However, there are some backlogs to full manifestation of this technology ranging from initial high cost to performance and reliability issues, among others. But in spite of these bottlenecks, new research trends have been assertive in seeking out a sustainable solution for harnessing wind energy for power generation -especially in the design and construction of wind generators. In order to motivate and prime a sustainable energy mix among stakeholders, this paper is a shot at appraising the theory of these innovative wind generators towards ecological sustainability, economy, efficiency, and employment creation.http://www.scielo.org.za/scielo.php?script=sci_abstract&pid=S1021-447X2015000300013&lng=en&nrm=iso&tlng=enPublisher's versio