IEEE Transactions on Energy Conversion, Vol.23, No.3, 774-780, 2008
Analysis of critical-speed increase of induction machines via winding reconfiguration with solid-state switches
Commonly used speed-control concepts permit speed ranges up to two-three times the base speed via voltage to frequency (V/f), that is, field-weakening control. This paper teaches the extension of the speed-control range up to nine times the base speed through online reconfiguration of the motor windings via electronic switches. The switchover of the windings, either from a winding with p(1) poles to p(2) poles, or from series to parallel connection of the number of turns per phase-so-called (V/N center dot f) control-lasts less than a 60-Hz cycle. Such fast switchover causes small transients only, and therefore, this concept is applicable to most variable-speed drives.
Keywords:change of number of poles;change of number of turns N;electronic switching of windings;increase of speed range;induction motor;voltage to N frequency (V/N center dot f) control