Microprocessor controlled DC power supply for the generator control unit of a future aircraft generator with a wide operating speed range

Embedded generators studied for the so-called more electric aircraft need to be capable of operating over wide engine spool speed ranges. Candidate technologies include the switched reluctance and the permanent magnet generators. The former may require a permanent magnet exciter (PME) in its generator assembly to provide power sources for the initial excitation and the generator control unit (GCU) for the self-sufficient requirement for aircraft generators. This paper studies the converter designed to provide logic and control power sources (+5 V, +/-12 V) for the GCU from the PME. The converter is based on three-stage conversion; the first stage rectifies the incoming three phase AC voltage, the second stage consists of a flyback topology which is controlled to achieve a 150 V output over the complete input voltage (25 V-350 V). This voltage is then fed into a universal switchmode power supply which converts this to the necessary control voltages. An initial prototype circuit has been developed and test results prove the capability of the proposed technology.