Browsing by Author "Kamper, Maarten J."

Now showing 1 - 6 of 6
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    Analytical modeling of surface-mounted and consequent-pole linear vernier hybrid machines
    (Institute of Electrical and Electronics Engineers, 2021) Botha, Christoff D.; Kamper, Maarten J.; Wang, Rong-Jie; Chama, Abdoulkadri
    ENGLISH ABSTRACT: This paper presents an analytical method for modeling the no-load air gap ux density of a surface-mounted and a consequent-pole linear Vernier hybrid machine (LVHM). The approach is based on simple magneto-motive force (MMF) and permeance functions to account for the doubly-slotted air gap of the LVHM. These models are used to determine the ux linkage, induced electromotive force (EMF) and average thrust force of each machine. The accuracy of the two analytical models is validated by comparison with 2D nite element method (FEM) solutions. Based on the analytical models, it is found that the working harmonics of both surface-mounted and consequent-pole LVHMs are essentially the same. However, the magnitudes of these working harmonics in the consequent-pole LVHM are invariably greater than those of surface-mounted LVHM. Further, using the analytical model, the contribution to the thrust force of the machine by each individual working harmonic can be shown clearly, and is used to explain why the consequent-pole LVHM has improved performance despite using only 50% of the permanent magnet (PM) material compared to the surface-mounted LVHM.
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    Analytical prediction of rotor eddy current loss due to stator slotting in PM machines
    (IEEE Xplore, 2001-08) Wills, Dominic A.; Kamper, Maarten J.
    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.
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    Contemporary wind generators
    (Energy Research Centre, 2015) Akuru, Udochukwu Bola; Kamper, Maarten J.
    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.
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    Cross-coupling inductance parameter estimation for more accurate performance evaluation of wound-field flux modulation machines
    (MDPI, 2020-10-22) Mabhula, Mkhululi; Akuru, Udochukwu B.; Kamper, Maarten J.
    ENGLISH ABSTRACT: In this paper, a proposed numerical frozen permeability modeling procedure is fully derived to accurately estimate the parameters of two variants of wound-field flux modulation machines (WF-FMMs) namely: wound-field flux switching machine (WF-FSM) and DC-excited vernier reluctance machine (DC-VRM). During the procedure, the contribution of saturation to the variation of the machine parameters is investigated. The parameter variation effects on the machine performance is also investigated. It is shown that analysis of WF-FMMs is better understood by using the proposed procedure which computes accurately the machine parameters.
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    Reducing PM eddy current rotor losses by partial magnet and rotor yoke segmentation
    (IEEE Xplore, 2010-09) Wills, Dominic A.; Kamper, Maarten J.
    In order to reduce the losses caused by eddy currents in the magnets and rotor yoke of a PM electric machine, a number of effective methods can be used. One method that imposes the least restrictions on machine performance is segmentation, which can be difficult to implement as magnets need to be cut, insulated and re-glued, which is a laborious and costly process. This paper presents methods of partial segmentation in magnets and the rotor yoke that aim to improve machine performance by reducing eddy current loss, while also suggesting realistic manufacturing possibilities. Results are obtained using analytical, numerical and experimental methods and good agreement is achieved.
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    Wind generator impedance matching in small-scale passive wind energy systems
    (Institute of Electrical and Electronics Engineers, 2021) Labuschagne, Casper J. J.; Kamper, Maarten J.
    ENGLISH 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.