Force formulation of a three-phase tubular linear machine with dual Halbach array

Abstract

A novel dual Halbach array is proposed in this paper to increase the output performance of tubular linear machines. The magnetic field distribution in three-dimensional (3D) space is formulated with Bessel functions analytically. Following that, the modeling of force output for linear machines with threephase windings is carried out based on Lorentz force law. The formula component of force ripple is separated from the analytical expression of total force. It is found that for multi-phase tubular linear machines, the force output and force ripple are not only closely related to the instantaneous position of the mover, but also the starting position. Therefore, the force output of the linear machine is formulated for three typical starting positions as a function of mover positions. The derived models are simulated with respect to the mover's motion. They are also validated with numerical results from finite element calculation. The study shows that an appropriate starting position of the mover helps to improve the output performance of the tubular linear machines. The proposed analytical force model can also be employed to analyze the influence of the structure parameters on the force output of linear machines with similar structures.

Design investigation of a coreless tubular linear generator for a Moball: A spherical exploration robot with wind-energy harvesting capability

“…The mover of "model B" consists of two dipole-PMs sandwiched between three irons [15][16][17]22]. It is well known that the Halbach PM array in "model C" concentrates the magnetic flux in a particular direction [18][19][20][21].…”

“…Based on that result, this paper considers the advanced design of a coreless linear generator intended for energy harvesting in a Moball system. Several previous works have considered coreless linear generators [21][22][23]. In [21], the proposed coreless linear generator contains a moving coreless coil and a Halbach-PM array as the stator to enhance the axial thrust.…”

“…Several previous works have considered coreless linear generators [21][22][23]. In [21], the proposed coreless linear generator contains a moving coreless coil and a Halbach-PM array as the stator to enhance the axial thrust. In [22], the proposed linear machine has coreless coils as a stator and a mover that consists of alternately-located dipole PMs and irons.…”

Magnetic Flux Distribution of Linear Machines with Novel Three-Dimensional Hybrid Magnet Arrays

“…However, the fabrication and magnetization of magnets are relatively challenging. Yan et al [ 22 , 23 ] extended conventional magnet array into three-dimensional topology, and proposed the novel dual Halbach array. It helps to improve the axial force output and depress the radial vibration.…”