| In today’s increasingly scarce fossil energy,wind energy has attracted widespread attention from all walks of life as a new form of pollution-free and renewable energy.In order to develop wind power generation vigorously and promote the grid price of wind power has become an inevitable requirement for the development of new energy power generation.Therefore,it has become an inevitable trend in wind power research to improve the capacity and efficiency of a single wind generator,thereby reducing the cost per kilowatthour.At present,the key factors limiting the increase in the capacity of wind generators mainly include the increase in the volume caused by the increase in the capacity of the wind generator,which increases the cost of the single unit and the difficulty of transportation;and when the power generation of the motor increases,the winding current is directly increased.And motor loss,resulting in excessive temperature rise in motor windings and other parts of the insulation can not afford.Based on this situation,this paper designs a 5MW semi-directdrive permanent magnet wind generator with one-stage gearbox that has the advantages of the current mainstream doubly-fed and direct-drive wind generators,and analyzes its operating characteristics analysis.First of all,starting from the working principle of the semi-direct drive permanent magnet synchronous motor,the multi-unit structure design method of the motor is introduced,and the structural characteristics of the multi-unit structure and the winding design method are described in detail.On this basis,the multi-unit structure design method of the motor is analyzed.The inductance characteristics and torque characteristics of the unit structure,the general mathematical model of the motor with this structure.In the design,the direct split method is adopted to reduce the difficulty of splitting the multi-unit motor.Secondly,the cogging torque of the semi-direct drive permanent magnet synchronous wind generator is analyzed and the magnetic pole shape is optimized with the main goal of reducing the cogging torque.Starting from the structure,the principle,calculation method,and general weakening measures of cogging torque are analyzed.On this basis,a magnetic pole shape optimization method is proposed.Based on the energy method,the influence of the magnetic pole shape on the cogging torque is numerically analyzed,and the magnetic pole shape is variable separated based on the numerical analysis,and the cogging torque and permanent The amount of magnet is the constraint function to design the optimal magnetic pole shape of the applicable motor.It is verified on the motor model that the optimized magnetic pole shape reduces the cogging torque by 76.9%.Thirdly,after designing the special structure of the motor,the overall design and optimization of the semi-direct drive permanent magnet synchronous wind generator are carried out.Using the equivalent magnetic circuit method for initial design,a 102-pole 315-slot semi-direct-drive permanent magnet synchronous wind generator was designed.It is optimized based on Taguchi’s method,using pole-to-slot ratio,permanent magnet thickness,pole arc coefficient,and stator tooth width as optimization factors,and motor efficiency,output torque,and cogging torque as the optimization goals.The orthogonal test is adopted.The optimization plan was determined,and the efficiency of the motor was increased from95.23% to 97.45%.Finally,the operating performance of the motor is analyzed.Including the finite element analysis of the no-load and load electromagnetic field characteristics of the motor,the loss of the rated pure resistance load,and the change of the temperature field,the operating characteristics of the motor are calculated.It is verified that the performances meet the design goals,meet the standards and material allowable limit requirements,and prove the feasibility of the designed semi-direct drive permanent magnet synchronous wind generator. |
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