A Fast and Accurate Analytical Model for Calculating Electromagnetic Performance of Helical Winding Slotless PMSMs

Helical slotless permanent magnet synchronous motors (PMSMs) are widely used in high-precision systems. In this article, a fast and accurate analysis model of helical winding slotless PMSMs is established to solve the problem that the current 2-D analysis method is not applicable while the existing 3-D finite element analysis method is complex and time-consuming. First, the PM field is analyzed considering the end effects. Second, the spatial current distribution of the armature is analyzed. Based on the 2-D analytical method and the spatial current density corresponding to different axial positions, an analysis method for the helical winding field is proposed. The Maxwell equations corresponding to different regions are obtained according to the motor structure. Then, the spatial distribution of the armature magnetic field of helical winding slotless PMSM is obtained by the separation of variables method. The air gap flux density correction function of the PM field and the flux density of the armature reaction magnetic field calculated by the analytical method are verified by the finite element analysis. Finally, the winding inductance, EMF, and electromagnetic torque, considering the end effects, are analyzed and verified by experiments on a prototype.