Assessment of permanent magnet generators for small-scale wind power applications -

Abstract

The economic and environmental costs associated with the ever- increasing use and combustion of various types of fossil fuels have shifted the global focus towards cleaner technologies that will reduce the fossil fuels consumption patterns through deployment of energy efficient and renewable devices and systems. The green energy industry including renewable energy and the energy efficiency industries are experiencing rapid developments associated with advanced research topics on issues related to their designs and operations. The role of wind turbine power generation has increased over the past decade. The use of wind power, as a mitigation technology, has been increasing at an annual rate of 20percent, with a worldwide capacity of 238,000 MW by end of 2011. One of the important components of the wind turbine system is the choice of electric generator. Several types of generators are used including brushed DC, induction and permanent magnet generators. In this thesis, an analytical design approach will be presented to show the advantages of permanent magnet generator over the induction generator for small- size wind turbine applications. The comparison is carried out with surface- mounted and interior rotor design configurations, making use of 3 types of magnets, neodymium iron boron, samarium cobalt and ferrite. An analytical approach for the surface- mounted and interior permanent magnet ac generator is conducted to calculate the generated voltage, induced torque and relevant mechanical speeds. The analysis will show that using permanent magnets for the ac generator will provide much higher performance characteristics compared to existing equivalent induction generators. Specifically, the magnetic loading of the machine will increase when different types of magnets are used for field excitation. This enhanced performance can be translated into a drop in the wind speed requirements. Accordingly, when using permanent magnet generators, wind power would be applicable for wider territories, thus increasing its mar