The need for fault tolerance in an aeroengine electric fuel control system

There has been extensive research concerning electrical machines and drives for safety critical systems. This work has led to the production of fault tolerant machines which are shown to be capable of operating with a large range of winding and power converter failures. The work reported has concentrated upon an electric fuel pump system. There has been little discussion of the reliability calculations which indicate the necessity of a fault tolerant system. This is partly because the reliability data for both machines and power electronic converters is both incomplete and commercially sensitive. This paper presents those results which are available, showing that redundancy is essential for the case of a main engine fuel pump drive. The most successful design approach has resulted in a multiple phase drive in which each phase may be regarded as a single module. The choice of phase number must be a compromise: high phase numbers increase system complexity, but reduce the overall mass, since the mass of a redundant phase is reduced. This issue is also addressed