Evaluating slip-frequency dependent load-condition variable in induction motor drive - deriving flux linkage components by integration, then squaring and dividing into torque using first order delay stage

摘要

The procedure is applied to evaluate an induction motor drive by dividing motor torque by flux-linkage squared. The rotor two-axis flux linkage components are found by integrating the rotor emf components and fed to each channel of a control circuit which evaluates the difference between actual and required values and reacts accordingly. The load variable is passed through a first-order delay stage, whose output is used in the control logic. A PD controller is used in the control circuit whose gain and time constant values are greater than the max. possible mismatch betwen motor parameters and parameters predicted by the control circuit. ADVANTAGE - Good dynamic and stability properties.