Some notes on the necessity to extend the vibro-acoustical tests of rotating electrical machines used in variable-speed drives

An analysis is made of the vibration and noise generation when an induction motor is fed by a frequency converter and works in a variable-speed drive, how the time harmonics in the supply voltage affect the excitation system, and how the variation of the exciting force frequency develops mechanical resonance. The vibro-acoustic problems of variable-speed drives are discussed from two perspectives. The consequences of supplying the machine with a voltage rich in time harmonics from an inverter are examined. Also discussed are the vibro-acoustic problems caused by the quasistationary speed variation within a wide range. A suggestion is made as to how the vibro-acoustical test requirements should be charged.<>