Investigation of Synchronous Reluctance Machines for Feed Drive Axes in Machine Tools

Synchronous reluctance machines (SynRM) are characterized by high efficiency in compared to asynchronous machines. Meanwhile, the rotor position is synchronized with the rotating magnet field, which theoretically makes it well suited for precise positioning tasks, such as for feed drive axes in machine tools. However, some of its inherent drawbacks, mainly the high torque ripple and saturation characteristic have so far limited its use on machine tools. This article experimentally investigates the application of SynRM for feed drive axes of machine tools, which require high speed and high accuracy positioning ability. In order to overcome the disadvantages of the SynRM, the conventional cascaded control loop in feed drive axis is modified by means of gain scheduling and feed forward control. The control performance is evaluated by different criteria in time and frequency domain. The comparison with a machine tool demonstrates that satisfactory result can be achieved by the proposed control schema for SynRM.