Electromagnetic Analysis of a Permanent Magnet Compulsator (PMCPA)

The eddy current distribution in the shield of a new type CPA is discussed. In this new type CPA, permanent magnet is used to produce excitation field. Because of the permanent magnet, the working mode of this type CPA is different from the conventional CPA that using electric excitation. Therefore the discharge process and the action of the shield should be analyzed to design the parameters of the CPA. By making some assumptions, the problem of the electromagnetic field distribution can be simplified and an analytical solution of the two-dimensional diffusion equations can be obtained. The transient eddy current distribution in the shield and the forces on the armature during the discharge are discussed. Finite element method (FEM) is used and the results show that the conclusions from the analytical solution are basically correct and can be used for preparing and optimizing design data about later passive compulsators