Optimal design considerations for a linear actuator with active magnetic suspension

The paper describes the detailed analysis that encompasses the magnetostatic design methodology of a linear electromechanical actuator. The actuator itself is a complex electromechanical system combining features of the active magnetic bearing (suspended mass in the order of 0.3 kg) and the linear Lorentz actuator (long stroke range - 50 mm). The basic design considerations are described and the tasks of the magnetostatic design are defined. The analysis and selection of the magnetic materials are carried out. A parametric search with respect to main design variables is performed. It has highlighted several peculiar features of the actuator performance, such as a strong long stroke position dependence of the suspension force and a cross-coupling between the suspension and the propulsion directions. A design procedure leads to modifications in dimensions and coils arrangement. The initial and the improved prototypes are compared on the basis of the finite element method (FEM) modeling and the measurement results, showing significant improvements in performance