In order to improve the manufacturing difficulty of the complex helical-shape magnetic pole (HSMP) in permanent magnetic serew

the structure of HSMP is improved and replaced. The static characteristies of thrust and torque were simulated with the finite element method (FEM). It is proved that the two kinds of permanent magnetic screws

whose screw is oblique ring magnetic poles (ORMP)

nut is HSMP

and screw is HSMP

nut is ORMP

can realize smooth transmission. Two practical improvements were carried out

because there were still

some HSMP in the structures. Scheme one was to combine andarrange several circular arc-shaped magnetic poles (CASMP) blocks in step. Scheme two was a semi-oblique ring magnetic poles(SORMP) composite strueture. The results show that the number of combined pole blocks required for the latter is less

it can ensure the smooth transmission of the motion system

at the same time

with greater thrust and torque. Compared with LRMG which screw and nut are HSMP

the thrust and torque errors are 3.981% and 0.583% respectively

so it is an ideal scheme to replace HSMP. In addition

the concept of pole pitch ratio

K

was proposed

and it is concluded that when

K

=0. 3

the thrust and torque of unit volume pole have the largest value

and the utilization rate of magnetic pole is the highest. On this basis

SORMP composite structure is optimized by Halbach array. The peak thrust and torque can be increased by 42.3% and 36.3% respectively

and the optimal auxiliary ratio

λ

=0.4.