Optimal design of auxiliary-teeth to solve circulation current reduction of permanent magnet linear synchronous motor

Abstract

A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM). Due to the unbalanced back electro-motive force (EMF) and impedance produced, unbalanced current is generated. The circulating current, which is caused by a decrease in the thrust, is generated by the unbalanced current. The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment (DOE), and compared with the basic model through finite element analysis (FEA). As a result, the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase. Also, this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.

Assessment of cogging‐force‐reduction techniques applied to fractional‐slot linear permanent magnet motors equipped with non‐overlapping windings

“…Of particular interest is a linear fractional‐slot per‐pole PM motor with double‐layer non‐overlapping windings, in which coils are wound on all teeth, in contrast to the single‐layer design in which coils are wound on alternative teeth. In this motor topology, auxiliary teeth are usually introduced to reduce the phase unbalance caused by open slots at both ends [11]. Consequently, undesirably large tooth‐ripple cogging force exists, as will be described in detail in Section 2.…”

Analysis and Calculation of the Normal Force Fluctuations of Permanent Magnet Linear Synchronous Motor

“…Document [6,7] calculated the normal force of PMLSM with Finite Element Method (FEM), obtained the expression by emulation fitting, analyzed the influence of amplitude of force ripple to the machine structure distortion. Document [8,9] analyzed flux density and electromagnetic force of moving-magnetic type PMLSM with Magnetic Circuit Analytical Method, deduced analytical expression of normal attraction force, without further analysis for force fluctuation. This paper is mainly focused on normal force fluctuation of PMLSM used in high-precision CNC machine tool servo system, deduce analytical expression of normal electromagnetic force wave of PMLSM with the method of MMF magnetic permeance; then, analyze the influences on the force wave order and amplitude when the coefficients of the electric machine are changed; Finally, base on a PMLSM with 6 poles and 36 slots, apply the Ansoft finite element analysis software to verify the effectiveness of normal electromagnetic force wave analytical expression.…”