Time-Scaled Emulation of Electric Power Transfer in the More Electric Engine

One of the main areas of research for the more electric aircraft (MEA) is mounting a generator on the low-pressure (LP) shaft in addition to the starter/generator mounted on the high-pressure (HP) shaft. Given that there are electrical machines on both the LP and HP shafts, there is an 'electrical bridge' to establish power exchange between the shafts. Potential improvements in the engine performance in terms of fuel consumption, engine stability, and compatible thrust with flight mission at various flight scenarios under such a transfer have been studied and discussed in the literature. To prove the concept and demonstrate the practicality of power transfer, an engine emulator has been constructed. The emulator will replicate the basic behavior of the engine by using similarity analysis to allow for conducting tests in a scaled environment without the need for an actual physical engine. A unique time-scaling technique is implemented to synchronize the time of the engine model and the test rig for transient studies. This enables scalable flexible engine emulation at different power generation ratings. A new criterion composed of shaft inertia, time, and speed scaling factors is also introduced to assess the validity of shaft inertia emulation. The experimental results are reported to demonstrate and further discuss the feasibility of electric power transfer between the engine shafts.