Magnetic field analysis of permanent magnet tubular linear machines with multiple movers

Conventional linear machine consists of only one stator and one mover. In this paper, a permanent magnet (PM) tubular linear motor with multiple movers is proposed to improve the efficiency of stator field. The outer and inner movers can produce independent motions by interacting with the PM stator. It can be used in large systems requiring multiple driven elements and space saving. The employment of tubular structure helps to reduce the flux leakage and improve the system working efficiency. The design concept and operating principle of the proposed linear machine are introduced. The magnetic field distribution in the machine is formulated by using Laplace´s and Poisson´s equations of magnetic vector potential. Following that, the modeling of force output for this machine is obtained based on Lorentz law. Numerical computation is also conducted on the flux field. It shows that the derived analytical model fits with the result of finite element analysis (FEA) well.