Simplified approach to the dynamic modelling of variable-reluctance stepping motors

The authors establish a simplified theoretical model for variable-reluctance stepping motors systems, based on the linearisation of the motor´s dynamic torque-producing characteristics about an arbitrary working point. It is shown that, by representing the torque as contours in the speed/switching angle plane, unambiguous stability limits for open and closed-loop operation are clearly defined. The authors show how the theoretical model provides valuable information about the mid-range instability of a stepping motor system, and provide experimental support for the model.<>