In conventional electrical machines the shear stress in the airgap has been shown to be equal to half the product of magnetic and electric loading. These quantities are limited by saturation levels in the iron and temperature levels in the copper respectively. In order to increase the shear stress available, then, it is necessary to depart from these topologies. Iron saturation is a material property and so cannot be altered, but the equivalent electric loading can be increased by the introduction of rare earth Permanent Magnets (PMs).

Figure 3.4: Equivalent current sheet of a PM

Figure 3.4 shows how a single permanent magnet may be modelled by two current carrying wires, producing an identical magnetic field. If these wires are thought of as

'current sheets', than the equivalent density can be greater than 900 kAm- , calculated using (3.5).

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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