Optimal design of synchronous torque couplers

The design of synchronous torque couplers based upon the utilization of high coercive force rare-earth cobalt permanent magnets is considered. For such units, it is generally required to obtain a given torque output with a minimum volume of magnetic material, subject to whatever design constraints may exist. The maximum torque for such optimized configurations is shown to be
5.6 \times 10^{-3} (B_{r}^{2}\bar{r}/\Delta)
and
10^{-2}B_{r}^{2}
per unit volume of magnetic material and inner coupler element, respectively, where
\bar{r}
is the average radius in the gap of width
\Delta, \bar{r}/\Delta \gg 1
, and B
r
is the remanent flux density. Examples of such optimal designs are given and possible alternate design criteria are briefly discussed.