Induction motor control system

摘要

In order to carry out commercial synchronous exchange for disconnecting an induction motor from its driving power supply and connecting it to a variable frequency power supply, or commercial synchronous switching for disconnecting the induction motor from the variable frequency power supply and connecting it to a commercial power supply, without any accompanying adverse shock, an induction-motor vector control technique is utilized. A phase-locked loop (PLL) is formed to detect the difference in phase between the output voltage from the variable frequency power supply or the magnetic flux phase of the induction motor on the one hand, and the phase of the power supply voltage on the other, so that the difference in phase thus detected can be maintained at a predetermined value.