Flux distribution and back-iron influence of tubular linear motors

Ferromagnetic material affects the magnetic field of electromagnetic actuators significantly. This paper studies the effect of back iron on magnetic field of linear motors. Designs of linear motors with single-sided, double-sided, and without back irons are analyzed quantitatively. The magnetic field for different structures is formulated analytically based on magnetic vector potential. The simulation result is compared with numerical result from finite element calculation. It shows that the analytical model fits with numerical result closely, and the use of back iron helps to enhance the magnetic field of linear motors.