Ultra-light Highly Efficient MW-Class Cryogenically Cooled Inverter for All Future Electric Aircraft Applications
With reductions in noise, emissions, and fuel consumption driving design, NASA has found that turboelectric distributed propulsion systems (TeDP) hold the most potential for powering commercial subsonic transport aircraft three generations from now. Deriving all propulsion from distributed electric motors entails immense amounts of electrical power. Current electrical propulsion systems in this power range are entirely too heavy and their losses too great for aircraft application. Cryogenic and superconducting electrical components have the potential to meet the low weight and loss required for the very high power transmission and electric motor drive systems.
NASA Future Electric Aircraft
The goal of this project is to build a 1-MW cryogenically cooled inverter with 99.3% efficiency at half power and 26 kW/kg specific power. The main technical barriers include highly-efficient power conversion stage and ultra-light EMI filter for MW-level high frequency cryogenically-cooled power conversion system. These challenges enable the following research opportunities, including but not limited to driving, protection, and characterization of power semiconductor at low temperature, characterization of passives at low temperature, topology, control, and PWM algorithm, advanced EMI filter strategy, cryogenic cooling system, packaging and integration. Also, additive manufacturing is employed to further improve the performance and reduce the weight of the power conversion system.
How WBG Can Help
When cooled to cryogenic temperatures, silicon performance approaches the capabilities of WBG semiconductors. Both on-resistance and saturation current have an inverse temperature relationship, so a Si MOSFET experiences much lower conduction and switching losses at low temperature. Our labâ€™s experience with WBG device characterization and WBG-based converter design can be leveraged in this project, even with conventional Si devices. This means ultra-dense board layout, optimized gate drive circuits, and high switching frequency.