The control methods for induction motors can be divided into two parts. In vector control, an ac induction or synchronous motor is controlled under all. What is the difference between a vector control drive and. Direct torque control dtc is one method used in variable frequency drives to control the torque and thus finally the speed of threephase ac electric motors. Induction motor scalar control free download as powerpoint presentation. Applied intelligent control of induction motor drives. Key words induction motor, vector control, scalar control, sluggish, higher order system effect, dsp. Control the rotor speed in an asynchronous machine asm drive using the scalar vf control method. Induction motor drives significantly contribute to the world energy consumption and several methods are available to control speed and torque of the. The simulation results show the increase of both the daily pumped quantity and pump efficiency, reached by the vector control. Comparative analysis between scalar control and direct torque control methods for induction motor drives 1hardik d. Vector control technique, squirrel cage induction motor.
However, this model is only acceptable for the wound rotor induction motors 2. The torque ripple is minimized and thus lower order harmonics are reduced. Scalar control of induction motor drives using dspace ds1104. The objective of foc is to achieve a similar type of controller with.
A comparative study was carried out on two control methods. Vector control, also called fieldoriented control foc, is a variablefrequency drive vfd. Hence only details of scalar methods are discussed here. Introduction of field oriented control scalar control such as the vhz strategy has its limitations in terms of performance. Note that you can save the final system state vector and use it as the initial state in a subsequent simulation so that the simulation can start under steadystate conditions. Scalar control vs vector control a galco tv tech tip.
Vector control is completely mathematical model on control of torque and speed of a threephase indirect vector controlled induction motor drive. Speed control of induction motor using vector control. But how the motor reacts to designed to that pwm pattern depends to the. In vf control methods, the stator voltage is adjusted in proportion to the supply. What are leading methods for vfd control of ac motors. Scalar control of induction motor drives using dspace.
Evaluation of direct torque control for highpower induction motor. Pdf vector control of 3phase induction motor by space. This paper analyzes control strategies for induction motors in. In this chapter special emphasis is on vector control of induction motor, though some aspects of scalar control for induction machine is studied. This speed can be varied by increasing or decreasing the supply frequency, though this results in a change. The overall block diagram of the flux vector control system a. Control methods for ims can be classified into scalar and vector types. The scalar control method is based on varying two parameters simultaneously. Higher order system effect, pi controller, rotor flux. The goal was to ensure maximum motor efficiency after extracting maximum photovoltaic power with mppt method. But when speed control is required, an ac motor is paired with a variable frequency drive vfd, which regulates the motor s speed by using one of two control methods scalar control or vector control to vary the frequency of the supplied voltage. In vector control, machine dynamic model rather than steadystate model on which scalar controllers are based on is used to design the controller.
Drm092, 3phase ac induction vector control drive with single. Control schemes for speed control of three phase induction motor the different control schemes of induction motor drives are including scalar control, vector or field oriented control, direct torque control, and adaptive control etc. Introduction the control of ac machine is basically classified into scalar and vector control. In scalar control, which is based on relationships valid in steady state, only the magnitude and frequency of. A comparative study on scalar and vector control of. However, to figure out the difference between vf control and vector control, theroetically speaking, only a few words are not enough.
Study and implementation of space vector close loop. Pdf analysis of scalar and vector control based efficiency. Ac motors are often used in equipment that runs at constant speed regardless of load, such as fans, pumps, and conveyors. Two control approaches of ac drives scalar control. This involves calculating an estimate of the motors magnetic flux and torque based on the measured voltage and current of the motor. In vector control, machine dynamic model rather than steadystate model on which scalar controllers are based on, is used to design the controller. Scalar control as the name indicates is due to magnitude variation of control variable only disregards any coupling effect in the machine. A comparative study on scalar and vector control of induction motor drives abstract. In order to control the motor the threephase supply is varied only in magnitude. A comparative study on scalar and vector control of induction motor.
Scalar control is relatively simple method compared to vector control. Vector control technique allows a squirrelcage induction motor to be driven with high dynamic performance, comparable with that of a dc motor. In scalar control, only magnitude and frequency of voltage, current, and flux linkage space vectors are controlled. Vf method speed control of induction motor duration. When i sell high speed motors, similar questions were also asked sometimes. Vector control, speed control, scalar control, sluggish. The latter paper explains vector control concepts allowing the induction motor, to behave as a simple separately excited dc motor. This paper proposes an alternative methodology for estimating the speed of a three phase induction motor driven by a voltage source inverter, using space vector modulation under the scalar control. By result analysis change in load torque speed attend reference speed in minimum time, by comprise with scalar control method.
Scalar control of ac drives power inverter alternating. Fast response of vector control make it better than other method of speed control of induction motor, by using this method we attend maximum response in minimum time. Comparison study of vector control of induction motor. A historical account of induction motor control is given, including scalar control, vector control, speed sensorless control and intelligent control. Since flux and current are in phase, it also describes the current in the stator. The controller generates reference voltages from the reference frequency by maintaining a constant voltagetofrequency ratio through scalar vf control. Vector control or field oriented control offers more precise control of ac motors compared to scalar control. What is the meaning of vector in vector control drives. Indirect vector control of multi cage induction motor. Introduction applied intelligent control of induction. A standard variable frequency drive scalar drive puts pwmpulse width modulation pattern designed to maintain constant vf ratio input to the motor under ideal condition. A more advanced switching algorithm, like space vector modulation svm, overcomes the drawbacks of the sine pwm algorithm and increases the overall system. Vector controlled induction motor drives the previous control strategies good steadystate but poor dynamic response oscillation resulted from the air gap flux vector control fieldoriented control is related to the phasor control of the rotor flux. Scalar control or vhz control is a simple technique to control speed of induction motor.
By contrast vector control involves the variation of both the magnitude and phase of the control variables. The motor speed, electromechanical torque, and currents observed during the starting of the induction motor drive are shown in starting the induction motor drive. Scalar and vector control of induction motor for online. One component defines the magnetic flux of the motor, the other the torque. The steadystate model of induction motor is mainly used to derive the technique, so transient performance is not possible. In this work the complete mathematical model of field oriented controlled induction motor is described and simulated in. Control of induction motor drives jp consultant training.
Understanding scalar vf control for induction motors. Vector control of an induction motor the sole idea behind the vector control of induction motor is to have an electrical drive which must offer superior performance than widely used separately excited dc motor in industry. So now that we have made that part clear, we are going to explain exactly how and what vector control is doing what it is doing. Field oriented control or vector control vc techniques are being used extensively for the control of induction motor. One might add that the vector that pops up in the description and the name of this drive technology is the rotating space vector that describes the flux in the motor. Scalar control is the term used to describe a simpler form of motor control, using nonvectorcontrolled drive schemes. Induction motor scalar control electricity electric power. Basic scheme of field oriented control of induction motor. Vector control technique allows a squirrelcage induction motor to be driven with high dynamic performance, comparable to that of a dc motor. In this paper a comparative study between the conventional scalar control and vector or field oriented. Study and implementation of space vector close loop control for induction motor. Singlecage type induction machines should be modeled with. Scalar control on the other hand, has no idea about the rotor position and only provides the motor with a speed set point to which the motor has to follow as well as it can, given load variances and other disturbances.
Spring 2004 introduction scalar control of an ac motor drive is only due to variation in the magnitude of the control variables. These factors make the control of induction motor difficult and call for the use of a high performance control algorithms such as vector control. Pdf speed control of induction motor using pi and vf. Blaschke introduces a new technology in industrial drives in 1968 and in early 1970s. Blaschke presented the first paper on fieldoriented control foc for induction. The different methods of speed control of induction motor can be broadly classified in to scalar and vector control methods.
It also details the established motor control metho d, the scalar control methodcontrols only the, which magnitude of. An955, vf control of 3phase induction motor using space. The previous control strategies good steadystate but poor. Vector control of induction motors pranjal barman research scholar department of electronics and communication engineering tezpur university 2. A comparative analysis of scalar and vector control of induction. Comparison between direct and indirect field oriented. Whereas, in vector control, the instantaneous positions as well as the magnitude. Vector control, also called fieldoriented control foc, is a variablefrequency drive vfd control method in which the stator currents of a threephase ac electric motor are identified as two orthogonal components that can be visualized with a vector.
Scalar control is the term used to describe a simpler form of ac motor control. The purpose of the scalar control technique is to control the magnitude of the chosen quantities. They are therefore used in high performance drives where oscillations in air gap flux linkages are intolerable, e. Scalar control of induction motor drives using dspace ds1104 h. Vf control using the sine pwm algorithm is a popular algorithm for ac induction motor control. The converter transforms a reference speed to a reference electrical frequency. This technique allows a squirrel cage induction motor to be driven with high dynamic performance comparable to that of a dc motor.
In induction motor control concepts where vhz technique is employed, the speed control is implemented by adjusting the stator voltage with respect to frequency such that the air gap flux is never able to deviate beyond the expected range of the steadystate, in other words it is maintained within. The explanation of vector control method is beyond the scope of this thesis. In high performance systems vector control methods are necessary 15. Pdf process and manufacturing industries are using field oriented control foc to drive the induction motor for desired performance. Comparison study of vector control of induction motor using rotor. The scalar control is very simple method for controlling the speed of induction motor compared to the vector control which is more complex.
487 366 1129 1033 22 162 100 658 124 341 1456 152 1410 84 1285 69 502 1473 1445 1250 362 752 647 929 913 541 230 769 817 1227 637 124