Magnetically Geared Pseudo Direct Drive for Safety Critical Applications

This paper presents an investigation into the electromagnetic design and performance of a fault-tolerant (FT) magnetically geared pseudo-direct-drive (PDD) electrical machine for primary flight control surface electromechanical actuation. It is shown that a large number of combinations of high-speed rotor pole pairs, pole-piece numbers, and stator slot numbers exist, for which a duplex three-phase FT configuration can be realized. Furthermore, in addition to facilitating a lower mass solution, it is also shown that a PDD presents a significantly lower inertia referred to the screw when compared to direct-drive or mechanically geared motor solutions. The findings are validated on a prototype PDD, which has been designed and built to meet the requirements of a primary control surface electromechanical actuator.