• Document: Induction motor control by vector control method.
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International Refereed Journal of Engineering and Science (IRJES) e- ISSN :2319-183X p-ISSN : 2319-1821 On Recent Advances in Electrical Engineering Induction motor control by vector control method. Miss. Bhagyashree Thool1 , Miss. Kalyani C. Wakhare2 1 (Electrical Engineering, Kits Ramtek, RTM Nagpur University,India) 2 (Electrical Engineering, SDCE,Seloo kate, RTM Nagpur University,India) ABSTRACT:- The 3-phase alternating current (AC) induction motors are mechanically simple, rugged, highly reliable, lower in cost per horsepower than DC motors and capable of more torque and efficiency than single- phase AC motors. A 3-phase AC induction motor can be controlled by varying its inputs according to a mathematical model of the rotor flux field in a complex vector space (vector control). Vector control provides efficient and accurate control of the motor’s speed and torque. The vector control analysis of an induction motor allows the decoupled analysis where the torque and the flux components can be independently controlled (just as in dc motor). This makes the analysis easier than the per phase equivalent circuit. Keywords: Constant Volts Per Hertz, dq Transformatn, Torque Speed Curve,. I. INTRODUCTION The induction motor, which is the most widely used motor type in the industry, has been favored because of its good self-starting capability, simple and rugged structure, low cost and reliability, etc. Along with variable frequency AC inverters, induction motors are used in many adjustable speed applications which do not require fast dynamic response. The concept of vector control has opened up a new possibility that induction motors can be controlled to achieve dynamic performance as good as that of DC or brushless DC motors. The v/f control principle adjust constant volt-per –Hertz ratio of the stator voltage by feed foreword control. It serves to maintain magnetic flux in the machine at desired level .it satisfy only moderate dynamic requirement .High dynamic performance is achieved by field orientation ,also called Vector control. The technique called vector control can be used to vary the speed of an induction motor over a wide range. It was initially developed by Blaschke (1971-1973). In the vector control scheme, a complex current is synthesized from two quadrature components, one of which is responsible for the flux level in the motor, and another which controls the torque production in the motor. Essentially, the control problem is reformulated to resemble the control of a DC motor. Vector control offers a number of benefits including speed control over a wide range, precise speed regulation, fast dynamic response, and operation above base speed. The vector control algorithm is based on two fundamental ideas. The first is the flux and torque producing currents. An induction motor can be modeled most simply (and controlled most simply) using two quadrature currents rather than the familiar three phase currents actually applied to the motor. These two currents called direct (Id) and quadrature (Iq) are responsible for producing flux and torque respectively in the motor. By definition, the Iq current is in phase with the stator flux, and Id is at right angles. Of course, the actual voltages applied to the motor and the resulting currents are in the familiar three-phase system. The move between a stationary reference frame and a reference frame, which is rotating synchronous with the stator flux, becomes then the problem. This leads to the second fundamental idea behind vector control. The second fundamental idea is that of reference frames. The idea of a reference frame is to transform a quantity that is sinusoidal in one reference frame, to a constant value in a reference frame, which is rotating at the same frequency. II. Methods of Speed control of Induction Motor: The various methods of speed control of 3-ø Induction motor are as under: 1. Pole Changing 2. Variable Supply Frequency 3. Variable rotor resistance control 4. Variable supply voltage control 5. Constant V/f control 6. Slip recovery 7. Vector Control Some methods are explained below: III. Variable Rotor Resistance Bapurao Deshmukh College of Engineering 17 | Page Induction motor control by vector control method. This method is applicable only to the wound rotor motor as external resistance can be added to it through the slip rings. A MATLAB code was developed to observe the variation in Torque-Speed characteristics of a 3ø induction motor with variable roto

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