Emulating DC Motor Control in AC Induction Drives using Field-Oriented Control (FOC)

Field-Oriented Control (FOC) transforms the control architecture of Induction Motors (IM) to emulate the decoupled dynamics of a separately excited DC motor. While DC motors naturally separate flux and torque through orthogonal windings, IMs feature inherently coupled, time-varying stator currents. FOC resolves this coupling by utilizing Clarke and Park transformations to project three-phase currents onto a synchronously rotating d-q reference frame aligned with the rotor flux. Within this coordinate system, the d-axis current regulates magnetization while the q-axis current independently controls electromagnetic torque, allowing for the use of standard PI regulators. Implementation on IMs requires precise rotor flux angle estimation, achieved by integrating the sum of the measured rotor speed and the estimated slip speed. Furthermore, feedforward decoupling compensation is integrated to mitigate cross-coupling effects at high speeds, and Space Vector Pulse Width Modulation (SVPWM) optimizes DC-bus utilization. This decoupling strategy ensures rapid dynamic response, minimized torque ripple, and maximum drive efficiency across the full speed range.