A rotary eddy-current brake or damper consisting of several sector magnets and a plate conductor of arbitrary shape

A method for analyzing a rotary magnetic damper (eddy-current brake) consisting of several sector magnets and a plate conductor of arbitrary shape is presented. The analytical solution to obtain the eddy current, braking force, and damping coefficient is obtained by dividing the magnetic flux into the narrow sector bands, and the unit step function is applied to solve the differential equation of the electromagnetic fields. The boundary condition of the plate conductor of arbitrary shape is satisfied directly by making use of the Fourier expansion collocation method. Numerical calculations have been carried out for the conductors of square plates, hexagonal plates, and elliptical plates, and the damping coefficients versus the variation of the flux range, the position, and the number of the magnets have been investigated in detail.