Problems of diagnostics of asynchronous motor powered by an autonomous voltage inverter

The article considers the most modern and most informative methods for diagnosing faults in squirrel-cage induction motors with a short-circuited rotor. The methods are based on the evaluation of vibrations and electrical parameters, as well as coordinates during operation and are normalized when powered from a sinusoidal voltage with frequency of 50 Hz. The main advantages and disadvantages of these methods, as well as the main indicators characterizing the general technical condition of the electric motor, are described. The application of these methods when powered from a non-sinusoidal voltage is impossible due to the complex harmonic composition of current and voltage. The consequence of this composition are the ripple moment and additional power loss. The interaction of the harmonics of the inverter and subharmonics, caused by faults, leads to the occurrence of a resonance phenomenon, and therefore to a decrease in the stability of the electric drive.