Design And Optimization Of Direct Drive Outer Rotor Permanent Magnet Synchronous Generator

Wind power generation is one of the most promising and large-scale approaches in the utilization of renewable energy.The direct-drive external rotor permanent magnet synchronous wind generator installs the rotor on the outside of the stator,which provides more space for magnetic pole installation,and does not need to install a tight ring to fix the permanent magnet,which has good heat dissipation conditions;no intermediate transmission device is required,and it is reliable High performance;easy to realize the effective use of wind energy in low wind speed areas.However,the motor still has problems such as high harmonic content of the air gap magnetic field and large amount of permanent magnet materials.Through the special design of the magnetic pole magnetization angle,the Halbach permanent magnet array is beneficial to achieve magnetization,increase the air gap magnetic field strength,and improve the power generation efficiency of the motor.At the same time,it saves the use of permanent magnet materials and reduces the manufacturing cost of the motor.This paper calculates the parameters of the motor’s stator and rotor size,electromagnetic load,pole slot ratio and other parameters to complete the parameter design that meets the motor design indicators.The motor design software RMxprt was used to complete the magnetic circuit calculation of the motor,and the preliminary design model of the direct-drive external rotor permanent magnet synchronous wind generator was obtained.Using ANSYS Maxwell finite element analysis software,the electromagnetic field simulation models of the 90-degree Halbach permanent magnet array and the 45-degree Halbach permanent magnet array is established.By comparing the air gap flux density and output voltage of the Halbach permanent magnet array motor and the traditional motor,it is proved that the 45-degree Halbach permanent magnet array can more effectively optimize the air gap magnetic field of the motor and improve the output voltage quality of the motor.The thickness and width ratio of the permanent magnet block of the 45-degree Halbach permanent magnet array are optimized,and the optimal magnetization scheme of the 45-degree Halbach permanent magnet array is obtained.Finally,a thermal simulation model of a 45-degree Halbach permanent magnet array direct-drive external rotor synchronous wind turbine was established in Ansys thermal simulation software.The temperature distribution of the motor under rated conditions,(0.5-1.5)times the rated speed,and(-10 to 40°C)ambient temperature are calculated.The simulation results show that there is no local overheating of the motor,and the Halbach array permanent magnet synchronous wind turbine can operate stably under different working conditions.