Optimal design of length factor for cross-coupled 2-DOF motor with Halbach magnet array

Abstract

This paper introduces an optimal design for a crosscoupled two-degree-of-freedom (2-DOF) motor. Generally, Halbach magnet array can realize high magnetic loading. Therefore, higher thrust force and torque will be obtained by employing Halbach magnet array. The proposed motor has a shaft, the permanent magnets, helical windings, and two bobbins. This structure can independently realize linear and rotary motions. Also, the mover part is constituted of the shaft and the permanent magnets which are segment shape and magnetized to the radial or the axial direction. Two kinds of magnets (magnetizations of axial and radial directions) are alternately placed at the shaft to axial direction. By determining the length factor which is the ratio between lengths of two kinds of magnets, the maximum thrust force and maximum torque will be found. In this paper, the optimal design is verified by varying the length factor of these magnets and performing the finite element analysis (FEA).

Key Parameter Design and Analysis of Flux Reversal Linear Rotary Permanent Magnet Actuator

“…A rotary linear switched reluctance motor was presented in [1], and its characteristics were analyzed by 3-D finite element method (FEM). Shodai Tanaka proposed a cross-coupled two-degreeof-freedom (2-DOF) motor with helical windings located in and out the bobbins in [2]. The cogging torque of a 2-DOF cylindrical actuator was reduced by changing the shape of stator and mover salient pole, which combined permanent magnet (PM) rotary synchronous motor and PM linear synchronous motor [3].…”

Dynamic magnetic‐coupling effect of two‐degrees‐of‐freedom direct drive induction motor

“…Its static magnetic fields are fully coupled, hence a two‐directional d‐q transformation was proposed to decouple the inter‐relation between the linear and rotary part . Besides, the interval between two successive magnets in the axial direction can affect the rotary and linear magnetic flux densities . Apart from 2DoF induction motor and permanent magnet motor, a rotary‐linear switched reluctance motor realizes 2DoF motion through several rotary stators, and its linear force was generated by the coupling of several rotary magnetic fields according to the mode of power supply .…”

Analysis of magnetic‐coupling effect on the performances of 2DoF direct‐drive induction motors

“…For the rotary‐linear permanent magnet actuator with a Halbach magnet array which can realise a high magnetic load, the static magnetic field was investigated [7] and the two‐directional d – q transformation was proposed to decouple the inter‐relation between the linear and rotary motions [8]. Further, the interval between two successive magnets in the axial direction affects the rotary and linear magnetic flux densities [9]. For the rotary‐linear switched reluctance motor [10, 11], linear force was generated by the coupling of multiple rotary magnetic fields, whose coupling intensity changed with the power supply mode of the motor.…”

“…Thus, the complex amplitude of the vector magnetic potential in the coupling magnetic field can be expressed as Ȧ m = Ȧ mi + Ȧ mo = Ċ 1 e η 2 2 + jG + η 2 α x − 4pτ + Ċ 2 e η 2 2 + jG − η 2 αx (10) where 0 ≤ x ≤ 2pτ. Therefore, the magnetic flux density of the coupling magnetic field can be calculated according to B m = ∂Ȧ m /∂x, as shown in (9):…”