Optimised designs of toroidal cage coils

The toroidal cage coil is a heavy-duty inductor used in power electronics. This paper studies the geometrical proportions of the coil, and gives design curves to maximise inductance for coil weight, to maximise inductance for overall volume, and to minimise power losses. The effect of an axial hole on the electrical properties is examined. Although the hole can provide much improved heat transfer, the reoptimised designs are generally less efficient than those without a hole.