This paper presents the effect of using the field orientation on the performance characteristics of doubly fed wound rotor induction motors. The field orientation technique is used to optimize the motor torque per ampere, resulting in minimization of the motor losses. This has been achieved by controlling the stator and the rotor voltages to operate the motor at unity power factor for primary power at all loads. Unity power factor operation increases the angle between the stator flux and the rotor flux to approach 90 degrees. This technique achieves field orientation without the need for a tachometer or position encoder to feed back the rotor position. Good agreement between the experimental and theoretical results is achieved.