Back-iron effect of tubular linear motors with dual Halbach permanent magnet arrays

Ferromagnetic materials affect magnetic field distribution and force output of electromagnetic motors significantly. This paper studies effect of back iron on tubular linear motors with dual Halbach array. The structure and operating principle of linear motors with dual Halbach array are presented. Numerical method in Ansoft environment is employed to compute the magnetic field and force output of linear motors with various types of back iron patterns including designs with internal back-iron, external back-iron, double-sided back-iron, and without back-iron. The study shows that the employment of back irons does help to enhance magnetic field and increase force output of electromagnetic linear motors with dual Halbach arrays.