Energy-Efficient Inverter-Fed Induction Motor Driving System

This paper deals with energy optimal control of variable induction motor drive which operates at constant mechanical power. At given steady-state operation point, the optimum efficiency is achieved by adapting the voltage- frequency correlation so that the active power absorbed by the motor is minimal. But, the minimum active power depends on the modulation strategy of the voltage inverter. In this paper, the search of optimum active power was achieved for pulse trains modulation strategy which simply allows developping high torques at low shaft speeds with respect to V/radicf control. The analysis reveals the energy efficiency improvement through the new optimal control. It is quantified on 2.6 kW motor drive how much energy optimal control can improve the system efficiency compared with constant V/radicf control. Several numerical results followed by some experimental verifications show that an efficiency improvement is obtainable by this optimal control.