Efficiency enhancement for indirect vector-controlled induction motor drive

In this paper, efficiency enhancement algorithms are developed and implemented on an indirect vector-controlled three-phase induction motor (IM) drive, and its performance under different operating conditions is analysed. The controllable electrical losses in the IM are minimised through the optimal control of direct axis (d-axis) stator current, and improvement in motor efficiency is achieved by weakening the rotor flux. The optimal d-axis stator current is also estimated using particle swarm optimisation (PSO) to validate the results obtained through analytical control method. The developed algorithms are tested under various operating conditions and the dynamic performance of the IM drive is analysed. The effectiveness of analytical and PSO-based efficiency optimisation control over conventional constant flux control, especially during light load at rated speed operation, is summarised. The effectiveness of the developed algorithm is validated experimentally through development of laboratory prototype set-up. The effect of parametric variation on efficiency, stator current, torque and speed of IM drive is studied through sensitivity analysis. The effect of variation in stator and rotor resistance due to change in operating temperature of the IM is also analysed and the robustness of the developed algorithm against parametric variations is demonstrated through simulation and experimental studies.