Optimal design of magnetic hysteresis couplers

Hysteresis couplers are commonly used within industrial applications requiring the transmission of a constant torque from zero to synchronous speed. Respect to the other coupler types, they feature low torque ripple and simple mechanical structure. This paper presents a comparison between different hysteresis couplers optimized in terms of average torque and permanent magnets volume. Two coupler topologies are analyzed along with two magnetic materials. Special attention is paid to the different behaviour of isotropic and anisotropic materials. The different coupler options are optimally designed with the aid of an automatic procedure making use of a computational effective performance evaluation method. A single static finite element analysis is carried out to calculate the flux density distributions within the device which are used in post processing to evaluate the transmitted torque via a simplified hysteresis model. The comparative analysis of the optimal designs allows drawing general guidelines particularly useful in the preliminary design stage of this class of electromagnetic devices.