Time-optimal single-step velocity response control scheme for field-oriented induction machines considering saturation level

A time-optimal single-step velocity response control scheme of field-oriented induction machines, taking magnetic saturation of rotor flux into account, is implemented based on the analytical solutions of the time-optimal control problem. High velocity response is achieved in spite of field-weakening for low acoustic noise or high-efficiency drives. The equation of the optimal control law is derived, and the look-up table is obtained. The optimal controls scheme is realized by simply adding the look-up table to the flux controller of the variable flux field-oriented control system. Simulation is carried out to verify feasibility of the proposed control algorithm. Problems of the overshoot of the rotor speed and the constraint on rate of change of acceleration or deceleration at the instant of switching from the time-optimal control to the conventional field-oriented control are discussed. The experimental results agree well with the simulation results, and show satisfactory dynamic and steady-state performance on both start-up and acceleration/deceleration