Dynamic performance of a rectilinear screw-thread motor

The paper describes the dynamic performance of a linear reluctance motor capable of operating over displacements of 1 m or more, with good positional accuracy. The main features of the motor, together with its static performance, were described in an earlier paper. The method of energising the machine is described. A detailed assessment of dynamic performance is made and this is verified by experimental results. The linear incremental open-loop transfer function is derived, taking into account eddy-current effects. Voltage-and current-drive performances are compared. It is also shown that eddy currents have a significant effect on dynamic performance. Measurements of open-loop performance and closed-loop force control are included.