A number of different topologies of PM wind generator were designed and compared. Permanent magnet generators became popular because they eliminate field windings and enable direct coupling of wind turbines. The practical design of a PM machine includes commercial material specifications and magnetic and electric circuit analysis. The design of PM machines is an iterative process with different parameter values. The permanent magnet (PM) machines provide high power density and high torque density. They have tremendous potential to reduce transmission and distribution losses by restricting grid expansion. Such systems provide power supply to remote locations that are not connected to common grid. The global installed capacity of small SAWES at the end of 2012 is 728.3 MW. Small SAWES play a vital role in meeting the demand for electricity.
The percentage shares of the leading countries such as China, USA, and Germany are 26.7, 21.2, and 11.1, respectively. The worldwide wind power installed capacity at the end of 2012 is 282.5 GW. Wind energy systems are widely used to generate electricity and help to improve the quality of life. Wind energy is clean, abundant, and renewable. The test results have good agreement with the simulation predictions. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The cogging torque of DRFPMG has been reduced without major change in induced emf. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. Three methods were applied to reduce the cogging torque in DRFPMG. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation.
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