Design and Analysis of a Field Modulated Magnetic Screw Without Permanent Magnet Skewing

One of the key challenges of magnetic screw concept is the fabrication of its helical permanent magnet (PM) poles. This article proposes a nonskewed PM field modulated magnetic screw (FMMS) based on the concept of three-dimensional (3-D) magnetic field modulation theory. The key of the proposed FMMS is that there are no helical PMs disposed. The conventional circumference and axial magnetic field distributions are arranged on the inner rotor and outer stator, respectively. Moreover, different structures of the intermediate translator are analyzed and compared, with the goal of optimizing thrust force. Besides, the 3-D magnetic field modulation theory is investigated and verified. Afterward, an optimized design is conducted on the discrete magnetic blocks to improve thrust force and ensure mechanical strength. Furthermore, the performance is analyzed and compared. Finally, the prototype is built to verify the magnetic transmission capability and 3-D magnetic field modulation theory.