A comparative design study and analysis of inner and outer rotor permanent magnet synchronous machine for power generation in vertical axis wind turbine using GSA and GSA-PSO

In wind energy conversion system, an electric generator is coupled with a wind turbine. The wind turbine is either vertical axis or horizontal axis wind turbine. To increase the efficiency the gear driven generator has been replaced by directly driven generator. This paper recounts the design optimization of inner and outer rotor permanent magnet synchronous machine of rating 500 KVA, 3.3 kV, 3-phase, and 600 rpm. The weight of the generator has been taken as an objective function. The gravitational search algorithm and its hybridization with particle swarm optimization have been used as tools for optimization. The temperature rise, efficiency, regulation and maximum flux density in stator teeth are taken as constraints for design problem. The results of both types of generator configurations are obtained and compared. It is found that the efficiency of outer rotor permanent magnet synchronous generator is improved by 2.19% and regulation by 2.83% as compared to inner rotor permanent magnet synchronous generator. Lower temperature rise as 22.61 °C is observed for outer rotor permanent magnet synchronous generator whereas it is 31.18 °C in case of outer rotor permanent magnet synchronous machine. Further, the sensitivity analysis has been performed over design parameters using local sensitivity method for both generators.