Khudoliy S. Improvement of efficiency of variable frequency drive by means of maximum load capacity control approach

The work is directed on development of approaches and solutions for im-provement of efficiency of variable-frequency electric drives with asynchronous mo-tors by means of special control strategy which provides maximal utilization of the load capacity of electromechanical system. A thermal observer for monitoring temperatures of electromechanical system is presented. The observer is based on three-mass dynamic thermal model of electric motor and single-mass model of converter. Practical application of the results obtained implies, particularly, better dimen-sioning of electric motor and its cooling system. Methods of thermal monitoring can also be applied for efficient thermal protection of electric equipment and improve-ment of overall productivity by reduction of equipment's downfalls. Dependencies between thermal state of electromechanical system and the load cycle of the mechanism are obtained. They can be used for optimal control strategy that allows maximum utilization of the load capacity in mechanisms with arbi-trary/unpredictable load cycle. The type of cooling system and technological re-quirements are considered.