Modeling of the winding coil temperature in a compact permanent magnet wind generator

Wind energy harvesting has existed since ancient civilization. Nowadays, wind energy is harvested to generate electricity using a wind generator. With the recent reduction in the price of high-performance permanent magnet, it is made possible to construct a highefficiency compact generator. One of the problems with the compact generator is temperature management. Hence, this study aims to develop empirical models in estimating the winding coil temperature for natural and forced convection cooling. The modeling process was started with conducting experiments at various operating conditions while observing temperatures at several locations on the wind generator. One of the challenges in conducting the experiment is that it consumed a lot of time for the temperature to reach its steady state condition. Thus, this study proposes a method to reduce the experimental time by estimating the settling time using a control system engineering modeling technique. By using the method, the experimental time reduces by 55% with the difference of 1% between the predicted temperature and the steady state temperature. Due to several limitations of the experimental equipment, experiments with high current output (more than 1 amp) cannot be conducted, this leads to the alternative of simulation experiments. The challenges of simulation experiments started with the difficulty to acquire parts dimension. A method is proposed to acquire the dimension by using an image processing technique. The next challenge is to generate a quality mesh during the electromagnetic modeling process. To tackle this problem, an adaptive meshing technique is used which resulted in magnetic flux value increases by 5.3% compared to an automatic meshing method. The electromagnetic modeling was successfully implemented and validated with the difference of less than 4.0% in Vrms (volt) between simulation and experimental results. The electromagnetic results were then transferred to Ansys Fluent for computational fluid dynamic analysis. The Ansys Fluent software was used to simulate heating and cooling effects via natural and forced convection at the wind generator. Two empirical models were developed to predict the winding coil temperature with the difference of less than 10.7% in the natural convection cooling results compared to the experimental results. As for the forced convection empirical model, it was used to estimate the maximum current output and temperature at various operating conditions. This study has proven that an empirical model can be used to predict the winding coil temperature at various operating condition with a good accuracy.