A Multifunctional T-Type 4-Leg Inverter for Various Operation Modes of Electric Aircraft Propulsion

When considering the mission profile of an electric aircraft power inverter, two main operating modes are of more interest. When the aircraft is climbing, 100% power output is typically demanded for a short time duration. The second operating mode of interest is cruise mode where much lower output power (e.g., 30% of rated power) is generally demanded for most of the flight time. High efficiency during the cruise mode is preferred to achieve longer flight range, while high reliability is also critical for such applications. In this paper, an advanced 3-phase 4-leg T-type inverter topology is developed, which provides the peak power during the climbing mode and high efficiency at the cruising mode, in addition to fault-tolerant capability to semiconductor switching faults. Specifically, this paper focuses on current-sharing operation during the climbing mode to provide the peak power and soft-switching at the cruising mode to achieve high efficiency, in which the redundant leg is leveraged when there are no switching faults. Simulation results are presented to confirm the inverter performance for electric aircraft application considering its specific mission profile. Current-sharing is applied during climbing conditions to reduce thermal stress on the outer IGBTs of the main phase legs by 5% of the junction temperature. Soft-switching is enabled in cruise mode to reduce switching losses of the inverter by 41.1% compared to that in a conventional T-type inverter.