الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Gears are a rotating mechanical system having cut teeth which mesh with another toothed part in order to transmit torque. A gear system, consisting of two or more gears working together is called a transmission and can produce a mechanical advantage through a gear ratio. Geared devices can change the speed, torque, and direction of a power source. Conventional mechanical gear has a high torque density, but suffers from some inherent problems; as friction, then noise, heat, and vibration. In contrast, magnetic gearbox offers significant benefits over its mechanical counterpart as the contactless power transfer, lubrication, maintenance free operations, reduced acoustic noise, minimum vibration, and inherent overload protection. Magnetic gearbox is basically a non-contact magnet-based mechanical power transmission, which uses permanent magnets to transmit torque between an input and output shafts without direct physical contact. For higher power ratings, magnetic gearbox will be smaller, lighter and with a lower cost. Magnetic gearbox has various topologies with a similar construction to its mechanical counterpart and has a lot of developing processes over the years. Cogging torque is one of the inherent drawbacks in permanent magnet machines as well as magnetic gearboxes, which results from the interaction of the permanent magnet and the airgap harmonics due to stator slotting. So an unexcited rotor will tend to align itself to a stable position. The torque cogging magnitude depends on the geometric parameters of the magnetic system such as the rotor position, number of poles, and number of stator teeth. Similarly in magnetic gearboxes, cogging torque is produced by the interaction between the magnetic flux produced by their parts and the variable permeance of the air gap due to the geometry. Cogging torque does not contribute to a useful torque, leads to speed ripple and vibrations. This thesis introduces some techniques for cogging torque reduction in magnetic gearboxes. For any general desired gear ratio, the torque ripple magnitude may be significant. In the available literature, certain fixed gear ratios are suitable to minimize cogging torque. However, for other ratios or even for these limited ratios, cogging torque magnitude may be unacceptable depending on the employed application. A conventional 14/4 radial and 16/4 axial magnetic gearboxes, which normally result in a significant cogging torque magnitude, are subjected to some modification techniques to reduce their cogging torque magnitudes. These techniques are based on step skewing or pole paring of the magnetic parts of the magnetic gearbox system. The proposed models of magnetic gearboxes are quantitatively analyzed using JMAG-10.4 designer finite element software. Simulation results will indicate a significant reduction in the cogging torque magnitude. Hence the optimum technique will be observed for each magnetic gearbox model.