Design and analysis of an outer rotor permanent magnet alternator for low-speed wind turbine

Abstract

The outer rotor permanent magnet alternator (PMA) is superior for small wind turbine system due to its robust, little maintenance and low cost configuration. In this research, the design and performance analysis of a radial flux outer rotor type PMA used for gearless, extremely low-speed, and small capacity wind turbine system has been discussed. The design has been simulated to analyze this PMA. The elementary configuration like material types, magnet types and additional electrical and mechanical parameters are studied, and the performances parameters of PMA are improved by changing these elementary electrical and mechanical parameters or some other related factors such as reducing the cogging effect. Cogging torque has been reduced by employing fractional slot per pole, width of slot opening, mounting of the magnets. Also the slot shape has been custom-made to increase the efficiency. The slot fill factor was improved by using different wire diameter used as winding coil. This improvement has been played a great role to reduce copper losses thereby improving the thermal condition of the slot. Finite element analysis (FEA) method was used to analyze this PMA in order to test the real time performance simulation with loss and cogging torque calculation. By taking all these considerations into account, higher efficiency from the outer rotor arrangement with minimum losses has been achieved.