Monitoring of load-fault-induced torsional resonances in high-speed alternators by speed and torque estimation

The goal of this research is the enhancement of avionic diagnostic and protection systems against load-fault-induced torsional resonances between on-board alternators and the driving turbines. Intermittent arc faults spreading over worn brushed slip rings supplying AC rotating loads (i.e. propeller anti-ice systems) may endanger the overall electrical service continuity by exciting mechanical resonances and ever-growing torque and speed ripples. Such phenomena are possible causes of breakage of the coupling joint ('mechanical fuse') between turbine and generator, as documented in a companion paper. Two online monitoring techniques for the early-detection of torsional resonances by sensorless speed and torque estimation are proposed to prevent this potential issue on aircrafts in flight.