Starting and vector control of series-connected wound-rotor induction motor in super synchronous mode

When the stator and rotor windings of a wound rotor induction machine are connected in series, electromechanical energy conversion is possible provided that the phase sequence of the rotor magnetomotive force is in the reverse sense to that of the stator. As a motor, the series-connected induction motor (SCIM) can operate at exactly double the synchronous speed for stable ranges of operation. The conventional super synchronous SCIM suffers from the absence of starting torque, and it has stability problems. In order to overcome the inherent starting and operating problems a novel vector control based technique has been proposed to achieve self-starting and stable operation for the SCIM. It has been shown both analytically and experimentally that the SCIM has higher torque capabilities compared to those obtained from a typical wound rotor induction motor.