Voltage sag effects on energy-optimal controlled induction motor with time-varying loads

In this paper, the impact of most severe symmetrical voltage sag (type A) on an energy-optimal controlled induction motor (IM) is analyzed with time-varying load (TVL). The simulation results are provided to describe the dynamic performances (speed and torque profile) of the motor under voltage sag. The results are compared with IM connected to 3-phase supply directly i.e without energy-optimal control (vector control). Model Based Control (MBC) is used to implement the said control. The effect of voltage sag in the operation of MBC is analyzed. To enhance ride through capability of IM and mitigate the effect of voltage sag, this paper investigates two techniques: (i) The Buck-Boost Converter, provides the desired DC link voltage (ii) Dynamic Voltage Restorer (DVR), provides the three phase voltage injection during voltage sag.