Control of Shaft-Line-Embedded Multiphase Starter/Generator for Aero-Engine

This paper deals with a shaft-line-embedded multiphase electrical machine to be connected to the high-pressure shaft of an open-rotor jet engine. An asymmetrical six-phase induction machine (IM) is proposed for this application. The main focus of this paper is on the control of the six-phase IM, to verify its overload capabilities and postfault operations. The implemented control uses a direct-flux vector control scheme based on a double-stator approach, where each three-phase winding set is independently controlled. This way, the fault-tolerant behavior of the drive system is enhanced. Complete details of the adopted flux observer are included; torque and speed control loops are implemented in a dedicated multiple three-phase drive, and a scaled prototype (10 kW, 6000 r/min) has been tested. The overload capability has been verified both in generation and motoring mode, for different speeds and torque up to 150% of the rated one. Finally, the transitions between healthy and faulty modes are reported for open phases and encoder faults. The obtained results demonstrate the feasibility of the proposed drive solutions.