Numerical design methodology of optimal trajectories for efficient induction motor drive based on a loss map

In order to drive the existing induction motors efficiently, the energy loss should be minimized during its operation. It has been reported that the analytically designed optimal torque and the rotating speed trajectories minimize the energy loss of the induction motor (IM) drive system under given drive conditions. In the reported analytical methods, however, the iron loss and other un-modeled loss are neglected. This paper proposes a numerical design methodology of the optimal trajectories of the motor torque and the rotating speed minimizing the energy loss by means of Linear Matrix Inequality (LMI). The motor loss is experimentally measured from the electrical input and the mechanical output power of IM, and the measured loss data are represented by a loss map. The loss map is composed by the rotating speed ω and the motor torque T. The evaluation functions are given by the drive conditions and the loss map, then the optimal trajectories are derived by solving the LMI optimization problem to minimize the evaluation functions. The effectiveness of the proposed method will be illustrated by means of some experiments.