Embedded Absolute Position Detection for Permanent Magnet Linear Motors with Passive Track

The absolute position detection scheme proposed in this paper belongs to the group of scale-less or embedded position detection methods. It uses the permanent magnets of the passive track of the permanent magnet (PM) linear motor as sensor target. As true absolute position detection it covers both (i) the position required for commutation and (ii) the position of the mover on the track even after a system shutdown and additional manual user interaction. The low-cost system approach consists of an array of linear Hall sensors mounted at the stator to evaluate the permanent magnet pattern on the passive track. The proposed sensor system is designed and analyzed in simulation and validated with a prototype system.