Detent Torque Estimation of Permanent Magnet Motors Using Stress Dependent Hysteresis Model

It is crucial to predict detent torque in the case of the servo motors for electric power steering systems. Thus, this paper proposes an improved method to estimate the torque of the permanent magnet motors using stress dependent hysteresis model. For analysis, the stator is divided into several areas on the basis of applied stress which is caused by press or shrinkage fittings to its housing. Following the conventional FEM(Finite Element Method) analysis in a non-stress condition, the hysteresis torque for each area is calculated with individual hysteresis models applied. Finally, the detent torque can be computed with sum of all hysteresis torque and the torque obtained from the conventional FEM.