Realization of time-optimal single-step velocity response control of field-oriented induction machines under the condition of nonsaturation of flux

A time-optimal single-step velocity response control scheme for field-oriented induction machines was implemented based on the analytical solutions of the time-optimal control problem in the case of nonsaturation of flux. High-velocity response was achieved despite field weakening for low acoustic noise or high-efficiency drives. Optimal control under conditions of startup, acceleration/deceleration, and constant speed control against impact load is considered, and approximate control methods were derived to simplify the control algorithm. The scheme was realized by adding the lookup tables of the optimal control laws to the conventional indirect field-oriented control system. The feasibility of the control scheme was verified by simulations and experiments that show fast and smooth velocity response. Numerical evaluation indicates that the time-optimal control is advantageous, especially when the mechanical response time is comparable with the electrical rotor time constant and when the rated flux is low