Speed Control of Inductions Motor by Changing Applied frequency

Abstract

Speed Control means intentional change of the drive speed to a value required for performing the specific work process. speed control is a different concept from speed regulation where there is natural change in speed due to change in load on the shaft. Speed Control is either done manually by the operator or by means of some automatic control device. Widely used in many industrial applications, the induction motors represent the starting point when an electrical drive system has to be designed. According to the non-liner relation between the voltage and torque of induction motor changing applied frequency method is useful . A 3-phase induction motor is practically a constant-speed machine. The speed regulation of an induction motor is usually less than 5% at full-load. In induction motor speed reduction is accompanied by a corresponding loss of efficiency and good speed regulation.