THEORY OF HYSTERESIS COUPLING TORQUE

Abstract

Abstract Hysteresis couplings find applications in many control requirements where the torque has to he independent of speed and angular position of the rotor and where a smooth, quiet operation is desirable. Because the developed torque is basically due to the hysteresis loss occurring in the rotor ring, a predominantly nonlinear phenomenon, the theoretical calculation of coupling torque is a complicated task. This paper presents a quantitative analysis of predicting torque of a salient-pole type hysteresis coupling from its design details and the knowledge of the magnetic properties of the rotor active material. The cardinal feature of the analysis derives from the special magnetic behaviour of the rotor annulus during operation. This allows the use of a ‘two-potential’ concept in deriving the final field components in the airgap and arbor regions of the coupling. The developed torque is then computed by the application of Poynting's theorem on a closed surface enclosing the rotor. The theory is applied...