Theory of eddy-current brakes with thick rotating disc

The braking forces acting on a thick conducting disc rotating in the field of rectangular electromagnets are examined. The analysis is based on the solution of quasi-one-dimensional vector potential in the plate and airgap regions of the device. Finite thickness of the plate is taken into account explicitly in deriving the general expression for the braking force. This expression is shown to reduce to the conventional induction motor characteristic in the thin plate limit and a simple original expression is presented for the calculation of braking forces in the skin-effect region.