Six-phase electrically excited synchronous generator for More Electric Aircraft

This paper proposes an electromagnetic design of an asymmetrical six-phase salient-pole synchronous generator for the aircraft power system. The generator is coupled to the aircraft engine and it is connected to 270V DC bus via a dual three-phase voltage source inverter. An electrical excitation current is fed to the rotor coil in order to produce the induced voltage in the stator windings. The external excitation possesses the advantage of controlling the output voltage by adjusting the excitation current. The generator is designed based on the performance of the synchronous machine at different load conditions and at different rotor speeds. In order to achieve an improved performance and an increased efficiency of the machine, the design of the stator windings and the rotor geometry is studied. The selection of the windings topology and the number of stator slots is discussed where the requirements of the aircraft variable speed generator are considered. The electromagnetic design of the machine is implemented and the Finite Element Method is used to analyze the performance of the machine. The control system of the DC bus voltage is discussed based on the machine characteristics obtained from the simulation based on Finite Element Method. The cross-saturation of the machine is considered at overload condition.