Stepper motors.

摘要

A stepper motor having a permanent magnet rotor (5) and a number of pole windings (1-4) which can be energised successively. The rotor angular position is sensed by Hall effect devices or reed switches and each pole winding is energised in dependence upon the position of the rotor and, in particular, before the preceding pole winding position is reached by the rotor. Where reed switches are used as the position sensor they can also perform the pole switching function. Speed control is obtained by control of the pole energising current and is thus divorced from any control of the frequency of the pole energisation. Very high speeds at very low powers can be attained.