Optimal motion trajectories minimizing loss of induction motor under amplitude limits

In order to drive the electric machines using the motors efficiently, the energy loss should be minimized during its operation. It has been reported that the design methodology of the optimal torque and rotating speed trajectories to minimize the energy loss of the induction motor (IM) drive system when the operation time period, rotating speed range, and rotational angle are given as drive conditions. However, the amplitude of the obtained optimal torque trajectory may exceed the maximum rating torque of the motor. The obtained optimal rotating speed trajectory also may exceed the maximum acceptable speed of IM. This paper proposes a design methodology of the optimal motion trajectories for IM drive system by means of the variational method and the Newton-Raphson iteration when the torque or rotating speed amplitude limit are given as additional constraint conditions.