Analysis of an Axial Permanent Magnetic Bearing for 1MW Horizontal Axis Wind

Abstract

One way to reduce maintenance costs while improving wind turbine efficiency is to replace mechanical bearings with permanent magnetic bearings. The permanent magnetic bearing is a free contact bearing in which the rotor is elevated from the stator by the magnet's repelling force. The purpose of this study is to analyze the variation of permanent magnet width and the gap distance between the rotor-stator magnets that can produce the magnetic axial force opposing the thrust force of 1MW horizontal axis wind turbines (HAWT). The method used in this study is a magnetic force simulation using finite element method by varying the magnet thickness, width of the gap, and displacement between the rotor-stator of the PMB model. The PMB model consists of rotor and stator magnets arranged in 3 layers with Nd2Fe14B type material with a magnetic flux density of 1.45 T. Variations in thickness of the rotor and stator magnets are 0.1; 0.15, respectively; 0.2 (m), while variations in the width of the magnetic gap are 4, 5, 6 (mm). The results of the study found that the displacement that produces an axial magnetic force that can support a thrust force of 199.5kN is the lowest in the PMB model with a magnetic thickness of 0.15m with a magnetic gap of 4mm, while the highest is at a magnetic thickness of 0.1m with a magnet gap of 6mm. The greater the thickness of the PMB axial magnet design, the greater the displacement that provides zero axial magnetic forces. Further, the maximum of the magnetic axial force is rise on with increasing magnet thickness.