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. Vector control technique, squirrel cage induction motor. A comparative study on scalar and vector control of induction motor. Vector control, speed control, scalar control, sluggish. Scalar control or vhz control is a simple technique to control speed of induction motor. The previous control strategies good steadystate but poor. Matlab simulation environment are taken to simulate both scalar and vector control for induction motor drive. Scalar control is relatively simple method compared to vector control.
Introduction of field oriented control scalar control such as the vhz strategy has its limitations in terms of performance. When i sell high speed motors, similar questions were also asked sometimes. 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. 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. But induction motor control drives are broadly classified in two category i.
The objective of foc is to achieve a similar type of controller with. Since flux and current are in phase, it also describes the current in the stator. The scalar controls are easy to implement though the dynamics are sluggish. The controller generates reference voltages from the reference frequency by maintaining a constant voltagetofrequency ratio through scalar vf control. 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. They are therefore used in high performance drives where oscillations in air gap flux linkages are intolerable, e. 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. Drm092, 3phase ac induction vector control drive with single. A comparative study on scalar and vector control of induction motor drives abstract. Control of induction motor drives jp consultant training. A comparative study on scalar and vector control of.
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. This involves calculating an estimate of the motors magnetic flux and torque based on the measured voltage and current of the motor. Introduction applied intelligent control of induction. In this work the complete mathematical model of field oriented controlled induction motor is described and simulated in. Whereas, in vector control, the instantaneous positions as well as the magnitude. Pdf speed control of induction motor using pi and vf. Comparison study of vector control of induction motor using rotor. Vector control, also called fieldoriented control foc, is a variablefrequency drive vfd. In vector control, machine dynamic model rather than steadystate model on which scalar controllers are based on is used to design the controller.
Pdf vector control of 3phase induction motor by space. What are leading methods for vfd control of ac motors. The goal was to ensure maximum motor efficiency after extracting maximum photovoltaic power with mppt method. Scalar control is the term used to describe a simpler form of motor control, using nonvectorcontrolled drive schemes. Singlecage type induction machines should be modeled with. Blaschke introduces a new technology in industrial drives in 1968 and in early 1970s.
Speed control of induction motor using vector control. This speed can be varied by increasing or decreasing the supply frequency, though this results in a change. Pdf process and manufacturing industries are using field oriented control foc to drive the induction motor for desired performance. In vector control, machine dynamic model rather than steadystate model on which scalar controllers are based on, is used to design the controller. Basic scheme of field oriented control of induction motor. Comparison study of vector control of induction motor. Scalar control is the term used to describe a simpler form of ac motor control. It also details the established motor control metho d, the scalar control methodcontrols only the, which magnitude of. This technique allows a squirrel cage induction motor to be driven with high dynamic performance comparable to that of a dc motor.
Vector control technique allows a squirrelcage induction motor to be driven with high dynamic performance, comparable with that of a dc motor. Vf control using the sine pwm algorithm is a popular algorithm for ac induction motor control. 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. The different methods of speed control of induction motor can be broadly classified in to scalar and vector control methods.
Pdf analysis of scalar and vector control based efficiency. The steadystate model of induction motor is mainly used to derive the technique, so transient performance is not possible. Scalar control of induction motor drives using dspace ds1104 h. Induction motor scalar control free download as powerpoint presentation. Part of the power electronics and power systems book series peps a majority of the existing variable speed drive systems with induction motors are lowperformance drives in which the adjusted variables are the magnitude and frequency of either the voltage or current supplied to the stator. 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.
In this paper a comparative study between the conventional scalar control and vector or field oriented. However, to figure out the difference between vf control and vector control, theroetically speaking, only a few words are not enough. Ac motors are often used in equipment that runs at constant speed regardless of load, such as fans, pumps, and conveyors. In vector control, an ac induction or synchronous motor is controlled under all. An955, vf control of 3phase induction motor using space. In scalar control, only magnitude and frequency of voltage, current, and flux linkage space vectors are controlled. The simulation results show the increase of both the daily pumped quantity and pump efficiency, reached by the vector control. Evaluation of direct torque control for highpower induction motor. The latter paper explains vector control concepts allowing the induction motor, to behave as a simple separately excited dc motor. Vf method speed control of induction motor duration. In this paper speed control of an induction motor using indirect field oriented control ifoc method has been developed and simulated. Scalar and vector control of induction motor for online. 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.
Study and implementation of space vector close loop. Comparison between direct and indirect field oriented. Field oriented control or vector control vc techniques are being used extensively for the control of induction motor. Understanding scalar vf control for induction motors. The motor speed, electromechanical torque, and currents observed during the starting of the induction motor drive are shown in starting the induction motor drive. Vector control of induction motors pranjal barman research scholar department of electronics and communication engineering tezpur university 2. Scalar control of ac drives power inverter alternating. Hence only details of scalar methods are discussed here. Vector control or field oriented control offers more precise control of ac motors compared to scalar control.
Vector control is completely mathematical model on control of torque and speed of a threephase indirect vector controlled induction motor drive. The converter transforms a reference speed to a reference electrical frequency. Introduction the control of ac machine is basically classified into scalar and vector control. A comparative analysis of scalar and vector control of induction. Scalar control vs vector control a galco tv tech tip. In high performance systems vector control methods are necessary 15. One component defines the magnetic flux of the motor, the other the torque. By contrast vector control involves the variation of both the magnitude and phase of the control variables. The scalar control method is based on varying two parameters simultaneously. Two control approaches of ac drives scalar control. The control methods for induction motors can be divided into two parts. This paper analyzes control strategies for induction motors in.
Scalar control of induction motor drives using dspace ds1104. 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. Induction motors are the most widely used electric motors due to its reliability, low cost,low maintaince. Vector control technique allows a squirrelcage induction motor to be driven with high dynamic performance, comparable to that of a dc motor. Applied intelligent control of induction motor drives.
The torque ripple is minimized and thus lower order harmonics are reduced. The overall block diagram of the flux vector control system a. Control the rotor speed in an asynchronous machine asm drive using the scalar vf control method. By result analysis change in load torque speed attend reference speed in minimum time, by comprise with scalar control method. 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. But how the motor reacts to designed to that pwm pattern depends to the.
What is the difference between a vector control drive and. 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. Induction motor scalar control electricity electric power. In order to control the motor the threephase supply is varied only in magnitude. Comparative analysis between scalar control and direct torque control methods for induction motor drives 1hardik d. Control methods for ims can be classified into scalar and vector types. Key words induction motor, vector control, scalar control, sluggish, higher order system effect, dsp. Blaschke presented the first paper on fieldoriented control foc for induction. A more advanced switching algorithm, like space vector modulation svm, overcomes the drawbacks of the sine pwm algorithm and increases the overall system. In vf control methods, the stator voltage is adjusted in proportion to the supply.
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. Study and implementation of space vector close loop control for induction motor. In this chapter special emphasis is on vector control of induction motor, though some aspects of scalar control for induction machine is studied. Induction motor drives significantly contribute to the world energy consumption and several methods are available to control speed and torque of the.
Spring 2004 introduction scalar control of an ac motor drive is only due to variation in the magnitude of the control variables. Scalar control of induction motor drives using dspace. Scalar control as the name indicates is due to magnitude variation of control variable only disregards any coupling effect in the machine. The explanation of vector control method is beyond the scope of this thesis. A comparative study was carried out on two control methods. In scalar control, which is based on relationships valid in steady state, only the magnitude and frequency of. Higher order system effect, pi controller, rotor flux. Indirect vector control of multi cage induction motor. What is the meaning of vector in vector control drives. A historical account of induction motor control is given, including scalar control, vector control, speed sensorless control and intelligent control. The scalar control is very simple method for controlling the speed of induction motor compared to the vector control which is more complex. 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.1360 1186 1466 830 1103 890 480 1060 514 1208 831 659 930 382 388 1082 1191 1114 61 547 1339 477 197 176 214 1378 493 131 381 438 457 954 18 186 344 627 1472 333