A fast nonlinear equivalent magnetic network model for magnetic jack type control rod drive mechanism in reactor

Due to high current and large air gap length, the magnetic jack type control rod drive mechanism (CRDM) features serious magnetic saturation and leakage. In this paper, a fast nonlinear equivalent magnetic network (EMN) model for the CRDM is proposed, which takes leakage, fringing flux and saturation into account. By proposed relatively fine division technique of magnetic reluctance, the proposed EMN model can fully consider flux distribution within the CRDM. To get a trade-off between model accuracy and solution speed, detailed modeling has been conducted in the air zone, which is a key area for energy conversion. Especially with the introduction of bypass reluctances, it not only considers the impact of working air gap length and magnetic saturation on fringing flux, but also refines the meshing around the working air gap zone. To solve the magnetic saturation problem, a relatively simple nonlinear iteration algorithm is implemented. The proposed EMN model predicts the magnetic density distribution, inductance, and electromagnetic force of the CRDM under various working conditions. The accuracy and high calculation speed of the proposed MEN model are verified in comparison with 3D finite element analysis (FEA) and existing EMN model.