Optimal design of synchronous torque couplers

Abstract

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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5.6 \times 10^{-3} (B_{r}^{2}\bar{r}/\Delta)</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10^{-2}B_{r}^{2}</tex> per unit volume of magnetic material and inner coupler element, respectively, where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\bar{r}</tex> is the average radius in the gap of width <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Delta, \bar{r}/\Delta \gg 1</tex> , and B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> is the remanent flux density. Examples of such optimal designs are given and possible alternate design criteria are briefly discussed.