Sensorless operation of a permanent-magnet generator for aircraft

This paper considers the operation and control of a brushless ac prototype embedded aircraft generator that has been designed for use as an alternative to the emergency run air turbine. To meet the wide operating speed requirements, the generator utilizes a hybrid rotor construction comprising permanent magnet and variable reluctance sections. The constant current source characteristics of the design are exploited to derive the phase information required by the ac vector controller, thus avoiding the use of a shaft-mounted rotor position sensor. The methodology behind the controller operation is presented together with test results taken from a prototype generator system, and this is contrast with the results taken from the conventionally controlled machine with resolver position feedback.