Magnetic Guidance of the Mover in a Long-Primary Linear Motor

Modern in-plant transport and handling systems benefit from using long-primary linear motors. To improve these systems, the lateral guidance of a vehicle is performed by magnetic forces instead of a mechanical guiding assembly. In this paper, an active guiding system is presented for permanent-magnet-synchronous linear motors with long and double-sided primary. The air gap and yaw angle are controlled while a simple wheel-rail system fixes the vertical displacement. Each side of the primary is supplied by its own inverter, allowing the necessary degree of freedom to control the air gap and yaw angle in addition to thrust. With this arrangement, a mover can be kept passive, avoiding any energy transmission system to it. Experimental tests were performed on a laboratory prototype. The experimental results show good dynamic performance that in turn provides stiffness in the guidance.