Energy Efficient Control of an Induction Machine under Load Torque Step Change

Optimal control of magnetizing current for minimizing induction motor power losses during load torque step change was developed. Original problem was slightly simplified and exactly optimal control was obtained for modified formulation. Obtained strategy has feedback form and is exactly optimal for ideal speed controller performance and absence of saturation in motor. Then original and simplified problem was compared in terms of quality of result and little difference found. The impact of limited bandwidth of real speed controller is analyzed. For case of main induction saturation the sub-optimal optimal control is suggested. Relative accuracy of sub-optimality is studied. Hardware implementation of optimal strategy and experimentation conducted with induction motors under vector control.