Magnetically geared pseudo direct drive for safety critical applications

The paper presents an investigation into the electromagnetic design and performance of a fault-tolerant 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 (HSR) pole pairs, pole-piece numbers, and stator slot numbers exist for which a duplex 3-phase fault tolerant 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 primary control surface electromechanical actuator.