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The speed-sensorless vector-controlled induction-motor drive is superior to the conventional vector-controlled induction-motor drive in terms of drive cost and reliability. In speed-sensorless control, one common practice is to estimate the flux position from the terminal voltage and current using a stator-voltage model. The accuracy of estimated flux position decides the performance of the vector-controlled drive. However, the performance is limited by the DC-drift problems that prohibit the use of open integration of the flux-producing voltage component for flux estimation. The paper proposes a flux-estimation method that gives the effect of open integration along with an inherent error-decaying mechanism to resolve the DC-drift problem. A stator-resistance-adaptation method is also incorporated in the flux estimator, which makes the flux-position estimation independent of resistive parameters of the motor. Using this flux-estimation algorithm, a rotor-flux-oriented speed-sensorless speed-control scheme of induction motor is proposed. The scheme is both simulated and experimentally verified. [ABSTRACT FROM AUTHOR]

Modelling of the switched mode power converter (SMPC) involves obtaining the large signal, steady-state and small signal representations. Transfer functions and state equations are used for mathematical representation of the SMPC. Obtaining these dynamic models using a mathematical or graphical approach sometimes lead to loss of an intuitive understanding of the system dynamics. A unified graphical method of modelling SMPC using bond graphs is presented. Only the PWM DC-DC converters are considered. The concept of switched power junctions is used for modelling of switching phenomenon in the SMPC. This approach uses a logical process of graphical reduction, which ultimately results in the state equations of the large signal and small signal AC models of the SMPC including the steady-state equations of the SMPC. This method is applicable to SMPC, in both continuous conduction mode and discontinuous conduction mode The proposed modelling approach is illustrated by a few examples. [ABSTRACT FROM AUTHOR]

Presents a topology for a voltage-space phasor generation equivalent to a five-level inverter for an open-end winding induction motor. Structure of the proposed inverter; Use of open-end winding induction motor; Absence of neutral point fluctuations.