Active damping control of induction motor drive with LC filter

Volts-per-hertz (V/f) controlled induction motor drive connected with LC filter may experience small-signal instabilities in different operating conditions and creates sustained oscillations in motor current, inverter current, motor voltage, developed torque and speed of the motor. This paper investigates the small signal instabilities of the drive at different speeds and load torques. This paper also proposes a simple active damping control technique which emulates the virtual resistance connected in series with the filter inductors and thus actively damps out the oscillations without any active power loss.