Induction motor stator windings asymmetry influence on frequency converter autonomous voltage inverter

Abstract

One of the reasons for deterioration of the efficiency of operation of a variable-frequency electric drive (VFED) with scalar control consists in occurrence of asymmetry of induction motor (IM) parameters. Apart from appearance of variable components of consumed power and electromagnetic torque, such asymmetry causes deterioration of operating mode of an autonomous voltage inverter (AVI). Assessment of IM stator windings asymmetry influence on heating losses revealed non-uniform current loading and, in its turn, uneven heating of transistors and bypass diodes of the AVI. The work included verification of VFED operation at different levels of stator windings asymmetry and use of a system of compensation for influence of IM asymmetry on the basis of the cross-vector theory of instantaneous power. Obtained results proved that the use of this compensation system causes decrease of unevenness of distribution of heating loss on power keys of the AVI.