The Advanced Air Transport Technology Power and Propulsion (AATT P&P) Advanced Power Electronics Team is prototyping a high efficiency, high power density, low output Total Harmonic Distortion (THD), altitude rated 250kW, 1kV motor drive. There are two primary goals for the design of the converter: to produce an inverter compatible with the NASA Electric Aircraft Testbed (NEAT), and to produce an inverter compatible with future high power, low inductance aerospace electric motors, specifically NASA GRC’s High Efficiency Megawatt Motor (HEMM). The inverter utilizes a multilevel topology to support widely available commercial off-the-shelf 1.2kV Silicon Carbide (SiC) MOSFETs to operate on a 1kV DC bus. The inverter also utilizes an interleaved topology which both enables accurate current sharing between multiple low current rated MOSFETs legs and provides additional filtering of the inverter’s output. The magnetics used for the interleaving filter are provided by the materials research group at GRC using their custom amorphous magnetic material, which is fabricated and tuned in-house. The aggressive packing density goal necessitates the thermal solution be compatible with a high heat flux, which is solved by tightly coupling the thermal design with the inverter’s internal structures. A lightweight altitude rated design is achieved by relying on a hermetically sealed enclosure, which allows the electronics to operate in a 1 atm environment, eliminating arcing issues incurred at low pressures and allowing for a high density design. Enclosure mass is minimized through tight packaging and a hybrid aluminum/carbon fiber shell. The software design centers on a Xilinx system-on-a-chip dual core processor and FPGA that heavily incorporates Simulink-based auto code generation for rapid prototyping. This presentation will include an overview of the design, as well as an update on the status of testing for the converter.
