Mechanical Characteristics And Loss Analysis Of Field Modulation Magnetic Gear

The field modulated magnetic gear transmits torque by mutual coupling of magnetic field,it is an environmentally friendly,safe and efficient transmission mode.It has higher and higher research value and many advantages of no friction,no noise,no oil pollution,less maintenance,low cost,easy installation and so on.This paper mainly improves the magnetic gear from the number and structure of permanent magnets,and increases the output torque and reduces the torque ripple under the premise of using the same amount of permanent magnets.In this paper,the air gap magnetic field generated by the permanent magnets of magnetic gears with and without modulation magnet ring is introduced.The air gap magnetic density produced by the inner and outer permanent magnets in the inner and outer air gaps is calculated by using the superposition principle,the harmonic component and the corresponding speed are calculated,the influence of the number of poles of the inner and outer rotor permanent magnets on harmonics is explained,the influence of different harmonics on the electromagnetic torque of the magnetic gear is analyzed.The inner and outer air gap magnetic field,harmonic component and torque of magnetic gear are calculated,and the working principle of field modulation magnetic gear is explained.The principle that the harmonic component in the air gap will change when the pole pairs of the inner and outer permanent magnets are different is used.By changing the pole pairs of the permanent magnets,the electromagnetic torque can be increased and the torque ripple can be reduced.Under the condition of ensuring the same electromagnetic dimension,the finite element model of magnetic gear with different pole pairs of inner and outer permanent magnets is established,and the air gap magnetic density,harmonic component and electromagnetic torque are calculated.Through the comparison and analysis of finite element simulation and data,it is shown that changing the pole pairs of inner and outer permanent magnets can effectively improve the electromagnetic torque and reduce the torque ripple.According to the principle that changing the permanent magnet form and magnetizing mode of inner and outer rotors can effectively improve the harmonic component,Halbach array with self-shielding characteristics and Spoke structure with magnetic gathering characteristics are adopted.A new field modulated magnetic gear with inner rotor permanent magnet using Halbach array is proposed.The N / S pole of inner rotor permanent magnet is uneven,the width of small pieces of permanent magnet in Halbach array is unequal,and the outer rotor permanent magnet with Spoke structure.The finite element method is used to simulate the traditional magnetic field modulated gear and the proposed magnetic field modulated gear.The transmission ratio of the two gears is fixed at 1:4.25,and the same electromagnetic size and permanent magnet dosage are used.Through the simulation,it is shown that the combination of the focusing effect of the spoke structure and the shielding characteristic of the sine magnetization can effectively improve the electromagnetic torque of the magnetic gear.At the same time,when the inner rotor permanent magnet adopts the unequal pole,it can also effectively improve the electromagnetic torque.This paper mainly studies the mechanical characteristics of field modulated magnetic gears,the average torque and torque ripple of magnetic gears with different transmission ratios are calculated,simultaneous interpreting the optimum transmission ratio of field modulated magnetic gears.A new topological structure of magnetic gear is proposed.The air gap magnetic density,harmonic component and torque characteristics of the magnetic gear and the traditional magnetic gear are compared.It is shown that the new magnetic gear can effectively increase torque and reduce torque ripple.