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It is generally aware that real-time parameter estimation of A.C. induction machine is very important for the efficient operation of vector-controlled drives. However, most existing methods have not taken into account of the four imperfections within the system, i.e. the existence of severe power harmonics due to the PWM inverter drive, the imbalancing of the 3-phase supply from the inverter, the variation of supply frequency under load changing and acceleration/deceleration, and changes in resistance. In this example, we have developed a new method of parameter estimation based on real time data sampling of voltages and currents, no matter they are sinusoidal or not. Here, the assumption of a synchronous rotating speed of the stator flux is not critical. With the aid of hybrid genetic algorithm techniques, the model has been found useful for on-line speed/torque control in most field orientation control schemes as it is much easier to achieve a global minimum during the optimization process.

A discharge estimator is designed and analyzed in this chapter to estimate the discharge with voltage, frequency and current without prior knowledge of head. A control of discharge in submersible pump is achieved by varying the motor speed. In VSI fed induction motor the speed is varied by varying the switching frequency. The ratio of frequency to the applied voltage is maintained constant, to keep the air gap flux at a desired value. The development of discharge estimator, PID and Fuzzy controllers are discussed in this chapter.