Optimizing the control strategy of redundant motor-inverter systems for aircraft propulsion application

Propulsion systems based on e-motor/inverter systems e.g. for operation of fuel cell battery hybrid powertrains are a key technology for enabling all electric aircraft. The efficiency of e-motor/inverter systems depends strongly on system design and control strategy. Two redundant motor systems were examined: one based on a direct-drive-system and the other based on a gear-drive-system. The study is based on the data of a previously performed manned flight of a 120 kW propulsion system. The flight data was used to test in a laboratory under real flight conditions. The study examines the energy utilization rate of the two motor systems along the flight profiles phases take-off, climb and cruise. An optimized control strategy with variable power distribution between the redundant e-motor/inverter systems for the gear-drive-system demonstrated a possible increase in energy efficiency of 2% over the duration of the tested flight profile. For the direct-drive system further optimization potential by changing the ratio of motor speed and torque for the same power was identified.