Doctoral Thesis: Design of High-Speed, High-Specific-Power Motor Drives for Megawatt Aircraft Applications

Friday, May 3
10:00 am - 11:30 am

2-190, MIT, 182 Memorial Drive, Cambridge, MA, 02139

By: Mohammad M. Qasim

Supervisor: Prof. David J. Perreault


  • Date: Friday, May 3
  • Time: 10:00 am - 11:30 am
  • Category:
  • Location: 2-190, MIT, 182 Memorial Drive, Cambridge, MA, 02139
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Thesis Committee: Prof. David J. Perreault, Prof. Jeffrey H. Lang and Prof. James L. Kirtley

The global momentum towards environment-friendly electric transportation has sparked the development of lightweight, compact electric machines and drives. With aviation contributing 4% of global emissions, hybrid-turboelectric propulsion and electric aircraft offer promising solutions to reduce CO2 emissions, fuel consumption, and flight noise. These compelling benefits have made electrifying aerospace a priority.

Designing high-specific-power motor drives poses multifaceted challenges. Such challenges pose design hurdles and performance limitations to electrified aviation, and overcoming them necessitates a co-design approach, careful component selection, appropriate converter topology selection, and close integration of power electronics with the electric machine.

This thesis explores the design and experimental demonstration of an air-cooled 1-MW high-specific-power distributed inverter system for a high-speed, lightweight motor drive for aircraft electric propulsion. Two identical machine drives are developed for the demonstrator system with back-to-back machines, inverter and rectifier subsystems, thermal management, and associated hardware. An inverter topology comparison reveals that sets of single-phase inverters are preferable to three-phase bridge inverters and multilevel inverters for high-speed, lightweight machines, offering the highest specific power and higher efficiency than three-phase inverters for equal device area, and current ripple. An extensive component selection study identifies commercially available components maximizing inverter specific power. A co-optimization process considers trade-offs between subsystems to achieve an overall-system optimum. High-frequency loss models estimate machine core and winding losses imposed by PWM waveforms. This thesis contributes to the design, construction, layout, and experimental evaluation of each 1-MW distributed converter system comprising 30 full-bridge inverters, achieving >50 kW/kg specific power and >98% efficiency. It presents the design and development of the control system of the back-to-back 1-MW motor-generator system, and validates the synchronized operation of the inverters with a central controller at rated voltage and current using multiple three-phase inductive load sets. This work pushes the boundaries of what is achievable in lightweight megawatt-class motor drives for aircraft applications, setting a new benchmark for future research and development in the field.

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