Speed Control of Induction Motor three Phase by Using Scalar Control Techniques

Abstract

A development of simulation model for scalar control of three phase induction motor is Presented in this report .scalar control as the name indi-cates is due to magnitude variation of the Control variable only , disregard any coupling effect in the machine. There are several methods Can be used to control the speed and torque of induction motor .But, the scalar control is a very Simple method for controlling the speed of induction motor compared to the vector control which Is more complex . this report presents the most popu-lar method of scalar control to control the Torque and speed of induction motor , which is about volts/hertz control method . The purpose of This meth-od is to maintain the air gap flux of induction motor in constant in order by maintaining The ratio voltage to frequency to achieve higher run time effi-ciency .This project is designed using Simulink/ Matlab software. this soft-ware also is used to simulate and plot the speed and torque Response of the V/Hz control system. These, in the steady state, are defined by their magni-tude and frequency and if these are the parameters that are adjusted, the con-trol technique belongs in the class of scalar control methods. A rapid change in the magnitude or frequency may produce undesirable transient effects, for example a disturbance of the normally constant motor torque. This, fortunate-ly, is not important in low-performance ASDs, such as those of pumps, fans, or blowers. There, typically, the motor speed is open-loop controlled, with no speed sensor required (although current sensors are usually employed in over current protection circuits).