Research on Temperature Distribution of Large Permanent Magnet Synchronous Direct Drive Wind Turbine

Abstract

A wind turbine is a conversion mechanism that converts wind energy into electrical energy, but the conversion efficiency cannot reach 100%, so there is partial loss. These losses are converted into thermal energy, which in turn causes the wind turbine to heat up and affect generator performance. Therefore, the cooling and temperature field analysis of wind turbines is very important. In this paper, an electromagnetic analysis model is established by using the parameters of a 4 MW wind turbine; the losses of each part of the generator under rated load and three-phase short-circuit conditions are calculated, respectively; and the heat source is imported into the workbench fluent software to determine the cooling mode, so as to obtain the magnetic-thermal-flow field coupling model of permanent magnet synchronous direct drive wind turbine. The temperature distribution and temperature rise of the generator are obtained. Under the rated load condition, the overall maximum temperature rise of the wind turbine is 41.4 °C, about 180 mm near the fluid outlet side, which is as high as the winding temperature rises, because the winding is the main heating body. The maximum temperature rise of the rotor model and the permanent magnet model is about 36 °C. Under the three-phase short circuit condition, the temperature distribution of each component is similar to that under the rated load condition, and the temperature near the fluid inlet is low; the lowest is only 29.8 °C. The higher the temperature at the fluid’s outlet, but not close to it, the higher the temperature is when it is about 180 mm away from the fluid’s outlet side. The temperature difference in the same axial length is relatively large, with a maximum temperature difference of about 120 °C. The temperature distribution and temperature rise of the generator are independent of the operating conditions, which mainly affect the value. Additionally, through experimental verification, the minimum error under the rated load condition is 1.05%, the maximum error is 3.3%, and the average error is 2.30%. The minimum error under the three-phase short-circuit condition is 1.5%, the maximum error is 3.62%, and the average error is 2.26%. The difference with the engineering error range requirements is small, indicating the reasonable and effective effectiveness of this method. This study aims to provide a strong reference for analyzing the cooling and magnetic thermal flow field and a coupling analysis of direct drive wind turbines.