Optimization Design Of Low Wind Speed Vertical Axis Generator And Magnetic Suspension Moto

Developing wind power is one of the important measures to realize “double carbon” goal,which has become a significant strategic demand in our country.Low-wind-speed wind power is one of the key research and development fields of Chinese wind power.The vertical axis wind turbine(VAWT)does not need to yaw,so it can effectively deal with the conditions that the wind direction changes frequently in low-wind-speed wind farms,therefore it is especially suitable for low wind speed wind farms.In view of the problems of high starting resistance moment and low utilization rate of wind energy in the existing vertical axis wind power system,this paper proposed a design scheme of low-wind-speed maglev vertical axis wind power generator and maglev motor with low cogging torque and low loss.The vertical axis wind power generator is the main generator,which is a direct-drive type permanent magnet synchronous generator(PMSG).The maglev motor adopts disc motor with hybrid excitation to reduce starting resistance moment and control suspension damping.The main work contents are as follows:First,according to the design characteristics and performance requirements of the main generator,the preliminary design of PMSG based on radial magnetization was completed.By combining equivalent magnetic circuit method(MEC)and finite element method(FEM),the simulation model of radially magnetized PMSG was established to explore the operation performance of the PMSG under different working conditions and make its performance meet the requirements.Second,on the basis of in-depth study of the characteristics of Halbach array,in order to further improve the performance of PMSG,Maxwell 2D software was used to establish the Halbach array PMSG model with magnetization angle of 90°,60° and 45°,and detailed simulation and comparison of PMSGs with different magnetization mode.The results show that Halbach array can optimize the performance index of PMSG,such as the air gap magnetic density,back electromotive force,cogging torque and electromagnetic torque and so on,which verifies the advantage of the PMSG with Halbach array.Among them,the Halbach array PMSG with 45° magnetization angle is the best.Third,according to the requirements of low starting torque,low loss and smooth operation for the main generator,with the cogging torque and iron consumption as the optimization objectives,the Halbach array PMSG was optimized to achieve low wind speed power generation.Based on the in-depth analysis of the mechanism of cogging torque,the analytical formula between cogging torque,pole parameters and stator structural parameters was derived by combining with the energy method.Three ways of weakening cogging torque were proposed,including changing the magnetizing angle of permanent magnet,the dimension of stator notch and the rotor segment skew pole.The effects of different magnetizing modes on eddy current were explored and the generator loss and efficiency were calculated.The simulation results show that the cogging torque and iron consumption are improved effectively,the starting resistance moment is reduced,and its efficiency is improved to 91.62%.Then,the optimized main generator is analyzed comprehensively.The results show that the waveform of the back electromotive force and output torque ripple of the optimized generator are improved effectively,which is more suitable for low wind speed power generation.Fourth,the maglev motor is designed,and verified by simulation.The maglev motor adopts disc motor structure: in order to achieve controllable suspension force and low energy consumption,the stator of the maglev motor adopts hybrid excitation;in order to weaken the cogging torque,the rotor slot is designed as a chute.Firstly,the topological structure and operating principle of the maglev motor were described.Secondly,the size parameters of the stator and rotor of the maglev motor were determined according to magnetic circuit calculation.Finally,the maglev motor model was established based on Maxwell 3D software,and the static field and transient field were simulated and analyzed respectively.The results show that the performance index of the maglev motor such as the suspension force,induced electromotive force,cogging torque,output torque met the design requirements.