Equivalent Circuit Model of Eddy Current Device

A new analytical model of axial-flux eddy current device is proposed in this paper, which is based on the equivalent circuit model. In order to simplify analysis, linearization at the mean radius is assumed in the 3-D model of eddy current device. In the equivalent circuit model, copper plate can be seen as a sum of coils in different volume elements. The equivalent circuit of coil is characterized by induced voltage, resistance, and inductance, which are calculated with the electromotive force, reaction flux, and linkage current in the copper plate frame of reference. To obtain these field solutions, the 3-D analytical computation method is employed to solve the Maxwell equations in Cartesian coordinate. The flux linkage equation, voltage equation, and torque equation are set up to depict the reaction field produced by eddy current and the function between the torque and slip speed in steady-state condition. With the equivalent resistance and inductance, the expression of torque becomes much simpler, and the inverse of which can also be obtained. Then, magnetic flux density, torque, and slip speed calculated by the proposed analytical model are compared with the 3-D analytical model and 3-D finite-element method.