The Field Orientation Principle in Control of Induction Motors

Abstract

In general, an electric motor can be thought of as a controlled source of torque. Accurate control of the instantaneous torque produced by a motor is required in high-performance drive systems, e.g., those used for position control. The torque developed in the motor is a result of the interaction between current in the armature winding and the magnetic field produced in the field system of the motor. The field should be maintained at a certain optimal level, sufficiently high to yield a high torque per unit ampere, but not too high to result in excessive saturation of the magnetic circuit of the motor. With fIxed field, the torque is proportional to the armature current.

Indirect Rotor Field Orientation Vector Control for Induction Motor Drives in the Absence of Current Sensors

“…According to the rotor field orientation vector control theory [4] [6], the stator current of squirrel-cage induction motor can be decomposed into two orthogonal components in the synchronous rotating rotor fluxoriented reference frame (M-T frame) which are, namely, the torque current TS i , which is to generate the electromagnetic torque, and the magnetizing current In most cases, the flux magnitude should be kept at some constant level, particularly when the motor runs below its base speed. So, (1) can be rewritten as…”

“…Conventional slip frequency control scheme does not use voltage and current sensors [4]. However, essentially, it is scalar control.…”

Robust Control of Sensorless AC Drives Based on Adaptive Identification

“…If for low power applications (i.e. servo drives), generally permanent magnet synchronous machines (PM-SM) and for very high powers electrical excited synchronous machines (SM) are used, the largest number of applications use rotor cage induction machines (IM) because of their higher mechanical robustness and lower cost (Birou et al, 2010;Holtz, 2002;Kelemen & Imecs, 1991;Leonhard, 1985;Moreira et al, 1991;Wieser, 1998;Trzynadlowski, 1994). The main disadvantage of using in the past the IM as motion source in variable speed applications, namely the difficulty to precisely control speed and/or torque, is now compensate by using: -power electronics in wide power range (voltage-source or current-source converters), to fed AC machines with variable amplitude/frequency power signals (voltage or current); -modern control methods, like field oriented based vector control (VC) or direct torque control (DTC) strategies of AC drive systems; -high frequency, real-time, digital computing systems, based on microcontrollers (μC) or digital signal processors (DSP), able to implement an perform the designed strategies and control methods.…”

Electric motor drives: Modeling, analysis and control, R. Krishan, Prentice‐Hall, Upper Saddle River, NJ, 2001, xxviii + 626 pp. ISBN 0‐13‐0910147

“…Most of the text and reference books devoted to control of converter-fed drives published in the last decade are restricted to AC motor drives [1][2][3][4][5][6][7][8]. This is quite understandable, because AC motors}especially induction cage rotor motor}thanks to their simple construction, reliability, ruggedness, and low cost have found wide industrial applications.…”

“…For mathematical description of drive systems with AC motors, the concept of a space vectors is commonly employed. However, in European countries (European authors) complex number representation [6][7][8][9][10] and in the USA two-axis real number representation is preferred [1,2,4]. The space vector based AC motor equations can be analysed in different reference coordinates (frames), e.g.…”