Abstract: “Process control and energy conservation are the two primary reasons for using an adjustable speed drive (ASD). However, voltage sags are the most important power quality problem facing many commercial and industrial customers. Voltage sag problem arise because of transients in supply voltage by the usage of heavy inductive loads. Therefore to improve the performance and reliability of the motor and drive, new controlling drives has to be implemented with the help of power electronics. Adjustable Speed Drives (ASD) is the emerging trend in the induction motor research to improve the performance during voltage sag conditions. The ride-through capability of the induction motor during voltage sag is taken into account that duration of the ride-through operation depends on the initial motor flux, speed level, rotor time constant, load torque and inertia. Also Inverter design mainly affects the motor performance. A new combination technique has been proposed for the mitigation of voltage sag”

Keywords: Speed drive, Voltage sag, Z- source inverter, Neutral linked Vienna rectifier.