2,786 research outputs found
Advanced flight control system study
The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed
Fault tolerant drives for safety critical applications
PhD ThesisThe correct operation of adjustable speed drives, which form part of a larger system, is
often essential to the operation of the system as a whole. In certain applications the
failure of such a drive could result in a threat to human safety and these applications are
termed 'safety critical'. The chance of a component failure resulting in non-operation of
the drive can be dramatically reduced by adopting a fault tolerant design. A fault tolerant
drive must continue to operate throughout the occurrence of any single point failure
without undue disturbance to the power output. Thereafter the drive must be capable of
producing rated output indefinitely in the presence of the fault.
The work presented in this thesis shows that fault tolerance can be achieved without
severe penalties in terms of cost or power to mass ratio. The design of a novel permanent
magnet drive is presented and a 'proof of concept' demonstrator has been built, based on
a 20 kW, 13000 RPM aircraft fuel pump specffication. A novel current controller with
near optimal transient performance is developed to enable precise shaping of the phase
currents at high shaft speeds. The best operating regime for the machine is investigated
to optimise the power to mass ratio of the drive.
A list of the most likely electrical faults is considered. Some faults result in large fault
currents and require rapid detection to prevent fault propagation. Several novel fault
sensors are discussed. Fault detection and identification schemes are developed,
including new schemes for rapid detection of turn to turn faults and power device short
circuit faults. Post fault control schemes are described which enable the drive to continue
to operate indefinitely in the presence of each fault. Finally, results show the initially
healthy drive operating up to, through and beyond the introduction of each of the most
serious faults.EPSR
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