Relationship between temperature and magnet skew angle in PMSG for low-speed wind applications

Abstract

The Permanent Magnet Synchronous Generators (PMSG) was generally used for low speed wind turbines. A skew magnet (rotor) was practically utilized for reducing the starting torque of the PMSG operating at low wind speeds. However, the thermal conduction in the air-coil (stator) can be effected by the magnet skew angle. The thermal conduction was then measured at three different areas, in the middle, at the surface and between the air-coil. The higher thermal conduction is found out to be located in the middle of the air-coil. When the skew angle was zero, the temperature maintained at 41.2°C for 120 minutes at 250 rpm while a 20 degrees angle skew resulted in the lower temperature at 39.5°C for 120 minutes at the same speed. At the higher turbine speed, 500 rpm, the non-skew magnet generated the temperature of 48.8°C for 120 minutes while the temperatures of a 20 degree angle skew read 46°C for 120 minutes. Overall, the magnet skewed angle at 20 degrees decreased the temperature by approximately 4.13% and 5.74% for 120 minutes at 250 and 500 rpm respectively. Therefore, the skew magnet angle can practically reduce the temperature in PMSGs for applications based on low-speed wind turbines.