Development of Megawatt-Scale Medium-Voltage High Efficiency High Power Density Power Converters for Aircraft Hybrid-Electric Propulsion Systems

Hybrid-electric propulsion system is an enabling technology to make the aircrafts more fuel-saving, quieter, and lower carbide emission. In this paper, a megawatt-scale power converter based on a hybrid three-level active neutral-point-clamped (3L-ANPC) topology is developed. To achieve high efficiency, the switching devices operated at carrier frequency in the 3L-ANPC converter are configured by the emerging Silicon Carbide (SiC) Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs), while the conventional Silicon (Si) Insulated-Gate Bipolar Transistors (IGBTs) are selected for the switches modulated at the fundamental output frequency. The dc-bus voltage is increased from the conventional 270 V to 2.4 kV to reduce the power cable weight in the aircraft. Unlike the traditional 400 Hz aircraft electric systems, the rated fundamental output frequency of the inverter here is boosted to 1.4 kHz to drive the high-speed motor. Systematic hardware development and new PWM strategy for the 3L-ANPC inverter will be presented in this paper, and the associated experimental results are shown to verify the performance of this MW-scale medium-voltage inverter. It is shown that the 1-MW power inverter achieves an efficiency of99% and power density of 12 kVA/kg, which provides a promising solution to the realization of high-efficiency high-density aircraft hybrid propulsion systems.