Permanent magnet motors used for optimum electric generating from small windmill

Small scale wind mill as wind energy converter system (WECS) with permanent magnet generator has great opportunity to develop for the islands of eastern area of Indonesia. Application of this appropriate technology will increase electrification ratio. Experiment and simulation studies of electric machines used for electric generating from small multi blades windmill were carried out. Diameter of the wind mill is 3 meters. The electric machines are 350 Watt brushless direct current (BLDC) motor with permanent magnet at rotors. The machine is used as electric generator by simple electric circuit addition for lamps to get its characteristics and for charging of 12 V and 24 V batteries. Wind speeds were 4 up to 9 m/s covered annual wind speed at Indonesia and rest of islands of eastern Indonesia. Results showed that the generators efficiency decreased when loads increased, 65.3% and 77.6% for 12 V and 24 V batteries charging. Two generators with a controller charged both batteries optimum. Transmission ratio of gearbox is 1:4 for primary generator and 1:5 for secondary generator. Maximum wind speed of primary generator for 12 V batteries charging is 7 m/s and switch to secondary generator for 24 V batteries charging. Minimum wind speed for 24 V batteries charging is 6 m/s and switch to primary generator.