Magnticalley Geared Direct Online Machine

This paper introduces direct online electric machines to achieve high torque at low speeds while maintaining a low number of poles. The proposed concept integrates line-start motor with a magnetic gear into a single housing with improved starting performance and rated operation torque density. Magnetic gears can scale the torque and speed of rotary systems, while avoiding problems associated with transferring torque through physical contact. The high speed PM rotor of the magnetic gear has Halbach structure and is physically integrated to the line-start rotor. The Halbach design restricts field interference between line-start and PM rotor, which helps with maintaining reliable and smooth starting performance with high locked rotor and breakdown torque capabilities. With Halbach design, the starting and steady state torque are smoother. Moreover, the Halbach design enhances magnetic field towards pole modulators of the magnetic gear, which enhances the power density of the proposed concept compared to the existing low speed, high torque solutions. Compared to the conventional mechanically geared system, the proposed solution is more compact with potentially increased mechanical reliability due to the reduction of mechanical contacts and does not require maintenance. When compared to the VSD fed direct drive systems the proposed solution provides improved torque density with cost saving potential.