Energy optimized control strategy for a variable input voltage three-phase induction motor

A method for improving the efficiency of a slightly loaded induction motor is suggested. It is based upon the optimal-efficiency power factor tracking by adjusting the input voltage. It has adopted the triac-converter fed induction motor drive system. All the control loops are implemented by the Intel 8754 microprocessor. By this method, 10% or more improvement is obtained at a quarter of the full load.