Operation of Variable-Frequency Drive Motor Systems With Source Voltage Unbalance

This paper describes efficiency measurement in induction motor and variable-frequency drives systems under imposed voltage unbalance at the drive input. A number of drives from different manufacturers are tested with matching sizes of motors and the results are compared. The results highlight differences in the effect of voltage unbalance on drive performance. The results also indicate that intrinsic motor performance has important influence on motor-drive system efficiency.