Torsional oscillations associated with the starting of three phase synchronous motors from a single phase supply

Studies have proved that the operation of three phase synchronous motors from a single phase supply is possible. This adds more flexibility to the operation of these motors and extends their field of application. However, previous work carried out in this respect neglected the effect of the torsional dynamics of the motor-load-shaft assembly, that exist particularly with motors driving reciprocating type multi-compressor loads. Such an effect may have damaging consequences when one or more of the natural frequencies of the mechanical system coincides with one or more of the natural frequencies of the electromagnetic torque components. This phenomenon is called electro-mechanical resonance. The main objective of this paper is to take the effect of this phenomenon into consideration through the development of a rigorous mathematical model coupled with a sound digital simulation.