Design methodology of a high speed switched reluctance generator drive for aircrafts

The paper proposes a high speed switched reluctance (SR) drive for aircraft applications, covering the demand of more electric aircrafts (MEA) and defending the particular benefits of this machine technology against others, such as permanent magnet synchronous generators. An appropriate topology of electrical machine and power converter for a high speed DC distribution grid is selected. Firstly, the electromagnetic design of the generator, by means of FEM, is described in detail, paying attention to the problem of the torque ripple and pointing out some solutions to improve it, based on an iterative optimisation of both stator and rotor geometries and phases activation and deactivation angles. Then, the design of power electronics is also analysed, obtaining the required modules and cooling system from a simulation model, using the maximum and average current levels as well as the duty cycles. The model has been developed from the generator electromagnetic design and integrates the control strategy, in charge of controlling the DC-link voltage. An iterative procedure using FEM analysis and the simulation model is also used to validate the thermal and mechanical behaviour of the system. Finally, the integration of the complete electric drive is discussed with the criteria of maintaining the system within the available room and keeping the temperature under the maximum limits. The application of aircraft equipment is specially demanding in terms of robustness, low maintenance, fault tolerance, high temperature and harsh environment, and those are the reasons why the SR generator is a reliable alternative.