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 is implemented, based on the analytical solutions of the time-optimal control problem in the case of nonsaturation of flux. High-velocity response is achieved despite field-weakening for low acoustic noise or high-efficiency drives. The optimal control under the operation conditions of start-up, acceleration/deceleration, and constant speed control against impact load is considered and approximate control methods are derived to simplify the control algorithm. The scheme is realized by only adding the look-up tables of the optimal control laws to the conventional indirect field-oriented control system. Feasibility of the control scheme is verified by simulations and experiments, which show fast and smooth velocity response. Furthermore, comparison with other control methods indicates that the time-optimal control scheme is very advantageous, especially when the mechanical response time is comparable to the electrical rotor time constant and/or when the rated flux is high.<>