Short primary linear drive designed for synchronous and induction operation in different sections

The potential for very long tracks, multiple vehicles travelling at high speed, high positioning repeatability and rapid acceleration turns the short primary linear drive into a good candidate for use in material transfer and processing lines. To implement this system, the linear motor was designed for synchronous and induction operation, since the costs can be considerably reduced by using a simple induction rail at the long transporting sections, instead of permanent magnets. This study is focused on the vehicle motion control strategy of a short primary linear drive, in order to regulate the speed without jerks. The implemented control algorithm for both the operations is based on a field oriented control, which uses a moving AB-reference frame. The position information was obtained by using a magneto-resistive incremental encoder, which was mounted on the vehicle, and a magnetic linear scale, which was installed along the passive track. Furthermore, force generation which depends on the vehicle´s position will be discussed. Finally, experimental tests are performed to demonstrate the feasibility of the employed control strategy.