Torque Analysis Of Concentric Magnetic Gear With Different Geometry Of Flux Modulators

The gears are widely used for torque transmission between the shafts of mechanical devices,and can also achieve torque and speed conversion.However,mechanical gears are subject to their construction and have significant drawbacks such as high maintenance requirements,low reliability,and vibration and noise.Compared with the transmission mode of the traditional mechanical gear,the magnetic gear transmission based on the magnetic field modulation type is a mode without mechanical contact,which can overcome some unavoidable problems such as friction loss,vibration and noise in the mechanical gear.It has high reliability,high efficiency,no lubrication during operation and overload protection.At first,this thesis introduces the principle of magnetic field modulation,and clarifies the relationship between the outer rotor surface-mounted magnetic pole pairs,the inner rotor pole pairs and the number of modulation blocks.In the concentric magnetic gear,the fundamental magnetic field of the local space at the inner and outer air gaps and the surface-mounted magnetic pole of the present side have the same pole pair number,so that the corresponding rotating magnetic field and the rotor is synchronously rotated to achieve magnetic coupling.Secondly,taking a typical magnetic field modulated magnetic gear as an example,the method of calculating the magnetic gear torque-angle characteristic curve and torque ripple is introduced.The torque is changed by the finite element simulation software Ansoft to change the initial angle of the inner rotor.Characteristic curve,which is used for fast Fourier analysis(FFT)of the waveform under a certain torque condition.Finally,the program used to calculate the harmonic distortion rate(THD)compiled in matlab software is used to obtain the corresponding torque ripple.The shape of the modulation block can significantly affect the harmonic magnetic field,which affects the torque-angle characteristic curve and torque ripple.Conventional modulation blocks are each fabricated and assembled using silicon steel sheets,however,it is difficult to overlap small silicon steel sheets.In order to make the modulation block structure simple and reliable,the connection bridge is introduced,so that the modulation blocks are connected into a single modulation ring,thereby making the manufacturing assembly simple.Finally,by changing the shape of the modulation block after joining the bridge and the position of the connecting bridge,the experimental modeling is carried out,the torque characteristics are obtained,and the torque performance is analyzed.Further,the block proportion of the modulation ring including the square modulation block is changed,and the influence of the change of the block ratio on the torque performance is discussed.