Prediction of pull-in rate and settling-time characteristics of a variable-reluctance stepping motor and effect of stator-damping coils on these characteristics

A theoretical method, described in detail in an earlier contribution, is extended to predict the dynamic response of a multistator, variable-reluctance stepping motor operating with multiphase excitation. Comparisons between experimental and predicted responses are made in terms of the settling time and pull-in-rate characteristics. The importance of allowing for core eddy currents in the theory is demonstrated. Consideration is also given to the feasibility of using closely coupled secondary coils on the stator to provide built-in electromagnetic damping for the motor. This too is considered regarding the effect produced on the settling time and pull-in rate.