Efficient numerical method for predicting the torque/displacement curve of saturated VR stepping motors

Accurate prediction of the torque/angle characteristic of variable reluctance stepping motors is difficult because their magnetic circuits are usually highly saturated. A complete numerical solution of the magnetic circuit would be lengthy and expensive, but it is shown that this is, anyway, unnecessary. An economic method of torque prediction is described. It is based on the separation of the magnetic circuit into `airgap¿ and `back-iron¿ regions, with numerical solutions being restricted to a simplified model of the gap region. This leads to economy in programming and computing times, but is capable of yielding accurate torque predictions.