Experimental study on position control system using encoderless magnetic motion (ICCAS 2013)

A position control system composed of a permanent magnet linear synchronous motor (PMLSM) as a stator and a magnetic plate as a mover is proposed in this paper. Rather than using a conventional encoder or resolver, position is measured by adopting a vector control method using two Hall sensors for generating a rectangular wave signal. This method estimates the velocity and position of a mover using the quadrature of two hall sensor signals instead of an encoder signal. Vector control of the PMLSM using two Hall sensors for generating a rectangular wave is proved to control the system in a stable and efficient manner through simulations. Hardware experiments reveal that the position control performance is within the range of 30~50μm with an accuracy of 10~20μm, a two-fold improvement over the conventional method. The proposed method exhibits an economical efficiency and practical usefulness. The vector control technique using two Hall sensors can be installed in a narrow place. Accordingly, the proposed method can be implemented in applications where conventional encoders or resolvers cannot operate.