This paper describes multiple electric field control methods for foil coils in high-voltage coreless linear actuators and their sensitivity to misalignment. The investigated field control methods consist of resistive, refractive, capacitive and geometrical solutions for mitigating electric stress at edges and corners of foil coils. These field control methods are evaluated using 2-D boundary element and finite element methods. A comparison is presented between the field control methods and their ability to mitigate electric stress in coreless linear actuators. Furthermore, the sensitivity to misalignment of the field control methods is investigated.
This paper presents a numerical modeling method for AC losses in highly dynamic linear actuators with high temperature superconducting (HTS) tapes. The AC losses and generated force of two actuators, with different placement of the cryostats, are compared. In these actuators, the main loss component in the superconducting tapes are hysteresis losses, which result from both the non-sinusoidal phase currents and movement of the permanent magnets. The modeling method, based on the H-formulation of the magnetic fields, takes into account permanent magnetization and movement of permanent magnets. Calculated losses as function of the peak phase current of both superconducting actuators are compared to those of an equivalent non-cryogenic actuator.
In this paper a cross-shaped isolator consisting of cuboidal magnets and a cylindrical isolator are compared by resonance frequency to volume ratio and shape. Both isolators are capable of obtaining a low resonance frequency, i.e. 0.15 Hz and 0.01 Hz for the cross and cylinder, respectively. The volume of both isolators is comparable, only the shape is different, resulting in a tall structure with a small footprint for the cross and a flat with a large diameter cylindrical structure. A sensitivity analysis shows that due to the large amount of magnets, the cross-shaped isolator is less sensitive to manufacturing tolerances.