Variable speed drive system, method of operating variable speed drive system, and method of cooling hydrocarbon stream

摘要

A variable speed drive system employing an electric motor and a frequency converter arranged between an AC power source and the electric motor is operated. The frequency converter functions to convert AC power obtained from the AC power source at a source frequency to converted power at a variable drive frequency. A mechanical assembly can be coupled to the electric motor. Electric modulation circuitry is provided interacting with the frequency converter. It is arranged to impose fluctuations, independently from any torsional excitation in the mechanical assembly and the AC power source, in the inter-harmonic frequencies of inter-harmonic currents generated in the frequency converter.