A Comparative Study of Speed Control Performance for Three-Phase AC Induction Motors between V/f Control and Field Oriented Control (FOC) Techniques using PLC and HMI

Abstract

Currently, three-phase AC induction motor control in industrial sectors still faces significant challenges regarding speed accuracy and high energy losses under varying load conditions, which traditional Scalar (V/f) control cannot adequately address. Therefore, this research aims to compare the performance of inverter control systems for a 0.37 kW three-phase AC induction motor between Scalar (V/f Control) and Vector (Field Oriented Control - FOC) techniques. The experiments were monitored and recorded using a Programmable Logic Controller (PLC) and an HMI NS5-SQ-11V2 interface under various load conditions and speed levels up to the rated speed of 1,410 RPM. The results demonstrate that FOC significantly outperforms V/f Control in all aspects: 1) Accuracy: FOC maintains a speed error of less than 0.5%, whereas V/f reaches an error of 7.8% at full load; 2) Dynamic Response: FOC exhibits an under-shoot of only 0.2% and a settling time of 0.5 seconds, which is approximately four times faster than V/f; 3) Energy Efficiency: FOC reduces current consumption by up to 21.6% and provides a higher power factor and overall system efficiency. These findings confirm that FOC is a highly effective control method capable of addressing these limitations, making it suitable for industrial applications requiring high precision and sustainable energy conservation.