Research And Design Of MW-class Direct-drive Permanent Magnet Wind Turbine

In recent years,due to global energy shortages,clean energy has been greatly developed.As a major form of clean energy,wind power generation has become more and more mature,and the capacity of wind turbines has continuously increased.Among various types of generators,direct-drive permanent magnet synchronous generators are preferred for use in large-scale wind power generation systems due to their simple structure,high efficiency,and no need for reduction gearboxes.This article will design a direct-drive permanent magnet wind turbine with a rated power of1.2MW.According to the research status at home and abroad and the actual production capacity of domestic manufacturers,this paper chooses the topology of the radial magnetic flux rotor.The main work of the thesis is as follows:First,according to the traditional calculation methods of high-power permanent magnet motor,the electromagnetic calculation of the MW-class direct-drive permanent magnet wind turbine generator is carried out,and the basic parameters of the motor are determined.The basic model of the motor is designed in Maxwell/RMxprt software.Second,after the motor model design is completed,it will be imported into Maxwell software for electromagnetic analysis.Under a static magnetic field,observe the motor's profile,magnetic field distribution cloud,and air gap magnetism.In the transient field,an external circuit of the no-load and rated load of the motor is built.The output voltage,motor torque,cogging torque,power factor of the motor,and motor efficiency of the motor in both cases are analyzed.Fourier analysis of the no-load back electromotive force.After a comprehensive analysis,the motor design is more reasonable,but the no-load back EMF has higher harmonic content and slightly worse sinusoidal characteristics.Thirdly,the demagnetization risk of the direct-drive permanent magnet synchronous generator designed in this paper is checked,and the external circuit control method is used to simulate single-phase short circuit,two-phase short circuit,and three-phase symmetrical short circuit motor fault,and the maximum demagnetization magnetic field is obtained.The radial magnetic density distribution curve of the permanent magnet magnet under the action of the momentum,and then the average flux density and the lowest flux density value are calculated by the field processor.The lowest magnetic susceptibility value of the motor under each fault type is compared with the inflection point of the demagnetization curve to determine whether the motor is irreversibly demagnetized.Finally,in order to improve the performance of the motor and improve the safety margin ofthe demagnetization operating point of the motor,this paper optimizes the motor on the pole arc coefficient and permanent magnet thickness of the permanent magnet,so that the motor is in the no-load back-EMF waveform distortion rate and anti-demagnetization capability.There has been some improvement.