| As the core component of wind turbine to complete energy conversion,the progress of its research and development technology is undoubtedly one of the wind vanes of the current development of wind power industry.With the rapid development of the wind power industry in recent years,the research and development of offshore wind turbines are gradually developing towards the direction of large capacity,modular structure,light weight,and convenient maintenance.Compared with traditional wind turbines developed in the past,megawatt-class high-power units require higher power density and higher stability when operating in more complex offshore environment.Under this development background,this thesis has completed the design of a 10 MW Semi-Direct Drive Medium Speed Permanent Magnet Synchronous Wind Turbine and the optimization of its cog torque and vibration.The main work is as follows:Firstly,this thesis determines the winding connection mode and the main size structure of the generator based on the rating parameters,design requirements and structural strength of the10 MW permanent magnet synchronous semi-direct drive wind turbine.Two kinds of generator models,fractional slot concentrated winding and integer slot winding,are established respectively to complete the construction of external circuit under no-load,load and short-circuit conditions,and the preliminary electromagnetic calculation based on finite element analysis is calculated.Secondly,in view of the excessive cogging torque in the generator design process,which causes the torque ripple to exceed the normal range,resulting in unnecessary vibration and noise of the generator,this thesis studies the principle and optimization process of Taguchi Methods.Based on the analysis of the generating mechanism and its suppression method of the generator’s cogging torque under no-load condition,a method to reduce the cogging torque based on the combination of Taguchi algorithm and finite element algorithm is proposed.The multi-objective optimization of the cogging torque and generator efficiency is carried out by determining the best matching mode of the pole arc coefficient and the chute Angle.The reliability,rationality and effectiveness of the method are verified by electromagnetic field simulation analysis.Then,the electromagnetic vibration caused by the electromagnetic force wave of the generator under the rated load condition is analyzed and extracted,and the relationship between the electromagnetic force wave generated by the interaction between the stator and the rotor of the generator and the air gap flux density is analyzed.Then the radial and tangential air gap magnetic density is extracted and compared,and based on this,the simulation analysis of the radial and tangential electromagnetic force wave density of the two generators is completed.Based on this,the frequency spectrum of electromagnetic force changing with time is analyzed,and the main distribution frequency band of high-order harmonics of electromagnetic force density is determined,which is combined with the results of modal analysis of stator core to determine the vibration of generator by means of harmonic response analysis.Finally,the finite element simulation analysis of the two optimized permanent magnet synchronous semi direct drive wind turbines is carried out,and the parameters of the two generators under no-load,load and short-circuit conditions are analyzed in detail.The rated load condition with id=0 is simulated by resistance capacitance load,and the demagnetization condition of permanent magnet under short circuit condition is simulated and verified.The results show that the performance of the two design schemes meet the design requirements and meet the practical engineering application,which provides a theoretical reference for the design of high-power permanent magnet wind turbine. |
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