Industrial traction applications demand operation ofthe drive in the high-speed region. The field oriented control based inductionmachine drive is a natural choice for these applications where the operation abovebase speed is easily achieved using field weakening approach. During the fieldweakening region, the machine is operated with a reduced flux level. The torquecapability of induction machine drives reduces considerably when the machineoperates in a deep field weakening region. Square-wave mode operation allowsmaximum DC-bus utilization resulting in enhanced torque capability for thedrive. Also, it results in reduced switching losses since the inverter switchesonly six times in each fundamental cycle. Hence, it is often employed in conjunctionwith field weakening techniques for traction applications in order to haveimproved torque capability along with better efficiency. However, once thedrive enters into the square wave operating mode, the stator voltage saturatesand thus the independent variation of the d-axis and the q-axis component ofstator voltage is not possible. This results in a loss of decoupling betweenthe flux and torque producing current components. Since the field weakeningschemes reported in the literature assume fully controllable stator voltage andcurrents, these methods cannot effectively work in square-wave mode.In this work, a newtechnique is proposed to control the drive in the square-wave mode where onlyone degree of freedom is available for control. In the square-wave mode, theproposed method controls the torque of the machine by directly varying thestator voltage angle with respect to the rotor flux axis. The flux of themachine is kept at a required value below the saturation limit by appropriateselection of the operating point. The proposed control strategy also offersgood torque dynamics in the square wave operating mode.