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Power-Quality Improvements in Vector-Controlled Induction Motor Drives
Published in L. Ashok Kumar, S. Albert Alexander, Computational Paradigm Techniques for Enhancing Electric Power Quality, 2018
L. Ashok Kumar, S. Albert Alexander
Scalar control means that variables are controlled only in magnitude and the feedback and command signals are proportional to DC quantities. A scalar control method can only drive the stator frequency using a voltage or a current as a command. Among the scalar methods known to control an induction motor, one assumes that by varying the stator voltages in proportion with frequency, the torque is kept constant. () VV0=ff0
Speed Control of Induction Motors and Synchronous Motors
Published in K Sundareswaran, Elementary Concepts of Power Electronic Drives, 2019
So far, scalar control of induction motor drives is discussed. In this control, frequency is increased to increase the speed, which brings down the air gap flux. To retain the air-gap flux, the voltage needs to be boosted; this process causes sluggish response. Sometimes, this can even lead to instability. Before going to the vector control concept, consider the simple circuit of a separately excited dc motor shown in Fig. 12.14.
FPGA in-the-loop implementation of direct torque control for induction motor
Published in Automatika, 2021
Ahmet Gundogdu, Resat Celikel, Besir Dandil, Fikret Ata
The high performance Alternating Current (AC) drivers developed for the controlling of induction motors that are widely used in industrial applications enable the control of the motor speed, torque or rotor position in the determined operating ranges. The control process on AC drives is performed as scalar or vector. In the scalar control method, the controlled variables are the stator voltage and stator frequency. By keeping the V/f ratio of the voltage and frequency applied to the stator as constant, the air gap flux is also kept constant; thus, it is tried to ensure that the motor generates constant torque at all speed ranges. In the regions of low and high speed where field attenuation is required, the motor exits from the constant torque region and continues to operate in the stationary power zone and thereby the motor’s torque constancy deteriorates. For this reason, scalar control method is not preferred for applications requiring precision position control. However, this method is widely used in applications that do not require high performance due to the fact that its implementation is easy and low-cost [1].
A new robust sensorless vector-control strategy for wound-rotor induction motors
Published in Australian Journal of Electrical and Electronics Engineering, 2020
The induction motor has been the workhorse of the industry because it is less expensive, more robust and capable of operation in harsh ambient conditions (Wu et al. 2011; Bimal 2002). These type of motors designed to operate at a single velocity, and determined by the frequency of the utility. As well the number of magnetic poles of the machine. The velocity control is much complex, compared to a DC motor, due to the nonlinear relationship between the current and torque of the motor. Nowadays, induction motors are found on applications such as pumps, blowers and industrial applications using scalar control techniques. The later, provide a reduced performance, but they are easy to implement, and inexpensive hardware can be used.
Control of Three-Phase Induction Machine Drives During Open-Circuit Fault: A Review
Published in IETE Journal of Research, 2022
Rahemeh Tabasian, Mahmood Ghanbari, Abdolreza Esmaeli, Mohammad Jannati
In recent decades, scalar control strategies have been developed in some studies because of its easy design, simple structure and low cost. This method is based on open-loop and closed-loop systems. Scalar control methods have the benefit of stability in medium to high speed ranges and it is not sensitive to the machine parameters [123,124,125]. However, scalar control methods do not guarantee dynamic performances of electric drive systems for serious loads since they are based on steady-state behavior of TPIMs. Furthermore, scalar control strategies do not satisfy efficient operation of TPIM drives [3]. In this section, scalar control methods based on calculation of MMF are reviewed.