Drive Topologies for Solar-Powered Aircraft

Solar-powered aircraft require electric drives for the main propulsion system. It is critical that these drives provide both very high efficiency and low mass. This paper discusses the relative merits of different machine topologies based upon maximizing efficiency, taking into account power-electronic losses, motor losses, mass, and size penalties. Laminated machines are usually limited in their efficiency at light load because of their iron losses. This paper shows how, by combining a high pole number with an ultralow loss lamination material, these machines can be more efficient than other more complex arrangements which have been adopted by others. A demonstrator machine has been built and predicted efficiencies have been validated by test. It has then been used to propel a solar plane to over 60000 feet and extend the aircraft flight-endurance world record from 30 to 84 h.