Sensorless synchronous motor drive for use on commercial transport airplanes

This paper describes a sensorless synchronous machine drive to be used for starting an auxiliary power unit (APU) on commercial transport airplanes. The proposed method utilizes a synchronous generator mounted on the APU, and presently only used as a source of electrical power, as a synchronous motor for starting the APU. The developed sensorless synchronous motor drive starting function involves measurement of machine terminal voltage and current, from which the desired current command is then calculated and implemented by the drive power converter. Power into the machine is determined by a power control loop, while the system voltage is limited to a desired value by a field weakening loop in the controller.>